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Climate variability effects on eutrophication of groundwater, lakes, rivers, and coastal waters in the Netherlands
Abstract
Many aquatic ecosystems in densely populated delta areas worldwide are under stress from overexploitation and pollution. Global population growth will lead to further increasing pressures in the coming decades, while climate change may amplify the consequences for chemical and ecological water quality. In this study, we explored the effects of climatic variability on eutrophication of groundwater, streams, rivers, lakes, estuaries, and marine waters in the Netherlands. We exploited the relatively dense monitoring information from the Dutch part of the Rhine-Meuse delta to evaluate the water quality response on climatic variability, in combination with anthropogenic pressures. Our results show that water quality of all water systems in the Netherlands is affected by climate variability in several ways: 1) through the process of global climate change (mainly temperature and sea level rise), 2) through changes Atlantic ocean circulation patterns (more southwestern winds), 3) through changes in continental precipitation and river discharge fluctuations, and 4) through local climatic fluctuations. The impact of climate variability propagates through the hydrological system 'from catchment to coast'. The fluctuations in water quality induced by climatic variability shown in this study give a preview for the potential effects of climate change.
... In Dutch lakes, the water temperature has risen through the past decades (Bolle et al., 2021;Mooij et al., 2008;Rozemeijer et al., 2021) at an above-average speed compared to worldwide trends (Rozemeijer et al., 2021). Four of the key resident fish species in these regions are bream (Abramis brama), perch (Perca fluviatilis), pikeperch (Sander lucioperca), and roach (Rutilus rutilus) (Jeppesen et al., 2012). ...
... In Dutch lakes, the water temperature has risen through the past decades (Bolle et al., 2021;Mooij et al., 2008;Rozemeijer et al., 2021) at an above-average speed compared to worldwide trends (Rozemeijer et al., 2021). Four of the key resident fish species in these regions are bream (Abramis brama), perch (Perca fluviatilis), pikeperch (Sander lucioperca), and roach (Rutilus rutilus) (Jeppesen et al., 2012). ...
... Such a limiting influence of food availability may have been exacerbated in the Dutch water system due to deeutrophication. Simultaneously, with increases in temperature, the water system in the Netherlands has undergone strong processes of decreased nutrient loading (Bolle et al., 2021;Rozemeijer et al., 2021). Nutrient levels in the Dutch main rivers and their tributaries were high in the 1970s and 1980s and decreased strongly in the decades afterward (Rozemeijer et al., 2021;van Bennekom & Wetsteijn, 1990;van Beusekom et al., 2019). ...
Growth is one of the most direct and common ways fish respond to climate change, as fish growth is intimately linked to the temperature of the environment. Observational studies on the effect of shifts in temperature on fish growth are scarce for freshwater fish, and particularly lacking for lake populations. Here, changes in growth rate of bream (Abramis brama), perch (Perca fluviatilis), pikeperch (Sander lucioperca), and roach (Rutilus rutilus) over three decades were studied and compared with changes in temperature in the two largest lakes of western Europe: Lake IJsselmeer and Lake Markermeer in the Netherlands. In the autumnal survey catches of bream, perch, and roach, the mean length of YOY increased significantly between 1992 and 2021 in both lakes, but for YOY pikeperch, no temporal changes were found. In a length‐stratified dataset of age groups of bream, roach, and perch, the relationship between length and age differed significantly between time periods. In the more recent time periods, indications for higher growth rates across multiple ages were found. Temperature during the growth season increased in the same decades and showed significant correlations with the YOY mean length, for bream, perch, and roach in both lakes, and for pikeperch in Lake Markermeer. These results point toward consistent temperature‐induced increases in growth over the age groups for bream, roach, and perch. These increases were found despite the simultaneous process of de‐eutrophication in this water system and its potential negative effect on food production. For pikeperch, it is hypothesized that the absence of temporal increase in YOY growth rate is related to its necessary switch to piscivory and subsequent food limitation; the lower thermal range of its main prey smelt, Osmerus eperlanus, is hypothesized to have inhibited food availability for YOY pikeperch and its opportunity to achieve higher growth rates.
... The discharge value (Q) is obtained by multiplying the cross-sectional area (A) by the velocity. Details can be found in Equations (2) and (3) [46][47][48][49][50]. ...
... The yearly sediment load production (SL) is computed as a function of the sub-catchment regions using the discharge value (Q) (m 3 /s) and TSS value (mg/L) as inputs. Additionally, using the Inverse Distance Weighing (IDW) interpolation approach, this parameter is used to calculate the graphical trends of level sediment load generation by sub-catchment [42,[50][51][52]. ...
... When the water flow in a basin increases, the TSS will also increase because the higher flow contains more energy to move the more concentrated suspended sediment load compared to the low flow level, and the high water flow also increases the rate of erosion. The comparison of the sediment load production values of the sub-catchment of Kenyir River to those of other sub-catchment river basins with similar areas is very high [50][51][52][53][54][55][56]. There are distributions of SL, such as the recorded values for the sub-catchment of Siput River (14.306 km 2 ) which are 55,409.54 ...
Lakes may take a while to respond to management interventions because of the management implications of incremental development and degradation issues. This includes the requirement for the ongoing participation of key lake basin management institutions and their operations. This study’s objective is to assess the impacts of land use activities along the Kenyir Lake Basin based on the sedimentation problem level. There are a few hydrological methods that are necessary indicators to measure the level of sediment production, such as Total Suspended Solid (TSS), area of sub-catchment, river discharge measurement, and annual sediment load production. The results showed that the sub-catchment of Besar River released the lowest annual average estimation at 3833.70 kg/km2/year, and the sub-catchment of Kenyir River produced the highest annual average estimation at 128,070.86 kg/km2/year for annual sediment load flow produced from tributary rivers into Kenyir Lake. Kenyir Lake Basin’s downstream and midstream regions had higher sediment load values than its upstream regions. This study highlighted the significance of the effects of anthropogenic factors, hydrological, geomorphological, growth, and developmental factors, and climate changes as the key variables attributing to the sedimentation phenomenon along the Kenyir Lake Basin. The construction of a long-term lake or reservoir catchment development and management plan, combined with the formation of a vision and comprehensive strategic plan, are vital components of sound management practice. The efficient implementation of the suggested watershed management programmes depends on the active involvement of all significant catchment stakeholders.
... Anthropogenic activities strongly influence nutrient cycling in ecosystems and have resulted in eutrophication of the European coastal marine and freshwater environments during the last century (Smith 2003;Ferreira et al. 2011). Phosphorus (P) and nitrogen (N) loads generally increased until the end of the 1980s, but were reduced following a ban on household detergents containing phosphates, improved nutrient removal in sewage treatment plants, and implementation of European legislation regulating fertilizer application (Rozemeijer et al. 2021). Reduction of nutrient loading generally improves ecological conditions in lakes (Kronvang et al. 2005). ...
... To this end, we used a unique dataset containing > 40 yr of monthly monitoring data on lake IJsselmeer, a shallow $ 1100 km 2 freshwater lake in the Netherlands in which toxic cyanobacterial blooms were a common phenomenon until the 2000s (Leeuwangh et al. 1983;Berger and Sweers 1988;Ibelings et al. 2005). Throughout 1970s till the 1990s, new legislation was implemented, among others the Dutch Pollution of Surface Waters Act, the European dairy produce quota (leading to reduced amounts of cattle and manure), and a ban on P detergents in Germany and the Netherlands (Rozemeijer et al. 2021). As a result of these, P input and concentration in lake IJsselmeer strongly decreased in the 1980s and was reduced down to 50% by the 1990s. ...
Nutrient loading of freshwater and marine habitats has increased during the last century as a result of anthro-pogenic activities. From the 1980s onwards, following implementation of new policy targeting eutrophication, total phosphorus (TP) and total nitrogen (TN) loads were reduced in many European waters. Often, however, decreases in TP were stronger as compared to TN, leading to increased TN : TP ratios. Our analysis shows that the large and shallow lake IJsselmeer (the Netherlands) experienced a similar trend, whereas TN was reduced by 50%, TP was reduced by 89% between 1975 and 2018. Most of this nutrient load reduction was achieved before the year 2000, changes in nutrient concentrations in the lake became smaller afterwards, especially for TN, leading to a further increase in stoichiometric imbalance up to a yearly averaged TN : TP (molar) of 296 in 2018. The observed changes in nutrients were accompanied by a decline in total phytoplankton biomass, and slight declines in phytoplankton genus evenness and diversity. Although biomass decreases likely resulted from the overall decrease in nutrient availabilities, the reduced diversity may have resulted from the shift toward very high TN : TP ratios that indicate relatively low TP levels and enhanced competition for phosphorus. Overall, our findings demonstrate long-term trends with decreased phytoplankton biomass and diversity following reduced nutrient concentrations and enhanced stoichiometric imbalance. Ultimately, such changes at the food web base may alter the structure and functioning of the entire aquatic food-web in lake IJsselmeer.
... River water temperatures are in close equilibrium with air temperatures, and climate warming is already impacting river thermal regimes (Whitehead et al. 2009;Minaudo et al. 2021;Rozemeijer et al. 2021). Warmer water temper-atures intensify in-stream and near-stream nutrient cycling processes as a result of increased rates of microbial activity, the proliferation of plant biomass (including algae and macrophytes), and enhancement of chemical reaction kinetics (Bussi et al. 2016;Jin et al. 2012;Whitehead et al. 2006). ...
... Warmer water temper-atures intensify in-stream and near-stream nutrient cycling processes as a result of increased rates of microbial activity, the proliferation of plant biomass (including algae and macrophytes), and enhancement of chemical reaction kinetics (Bussi et al. 2016;Jin et al. 2012;Whitehead et al. 2006). Under climate warming, higher rates of in-stream nutrient processing are also likely to be further magnified by low flows, increasing water residence times, and therefore water contact time with benthic, riparian, and hyporheic (i.e., sediment and porous space adjoining a stream bed) sediments and biota (Whitehead et al. 2009;Rozemeijer et al. 2021). Warmer water temperatures drive sorbed-P release from bed sediments due to higher rates of microbial mineralization of organic matter, loss of dissolved oxygen, and reductive dissolution of redox-sensitive metal oxides (Jarvie et al. 2020). ...
This study is a meta-analysis of global articles on hydrological nutrient dynamics to determine trends and consensus on: (1) the effects of climate change-induced hydrological and temperature drivers on nutrient dynamics and how these effects vary along the catchment continuum from land to river to lake; (2) the convergence of climate change impacts with other anthropogenic pressures (agriculture, urbanization) in nutrient dynamics; and (3) regional variability in the effects of climate change on nutrient dynamics and water-quality impairment across different climate zones. An innovative web crawler tool was employed to help critically synthesize the information in the literature. The literature suggests that climate change will impact nutrient dynamics around the globe and exacerbate contemporary water-quality challenges. Nutrient leaching and overland flow transport are projected to increase globally, promoted by extreme precipitation. Seasonal variations in streamflow are expected to emulate changing precipitation patterns, but the specific local impacts of climate change on hydrology and nutrient dynamics will vary both seasonally and regionally. Plant activity may reduce some of this load in nonagricultural soils if the expected increase in plant uptake of nutrients prompted by increased temperatures can compensate for greater nitrogen (N) and phosphorus (P) mineralization, N deposition, and leaching rates. High-temperature forest and grass fires may help reduce mineralization and microbial turnover by altering N speciation via the pyrolysis of organic matter. In agricultural areas that are at higher risk of erosion, extreme precipitation will exacerbate existing water-quality issues, and greater plant nutrient uptake may lead to an increase in fertilizer use. Future urban expansion will amplify these effects. Higher ambient temperatures will promote harmful cyanobacterial blooms by enhancing thermal stratification, increasing nutrient load into streams and lakes from extreme precipitation events, decreasing summer flow and thus baseflow dilution capacity, and increasing water and nutrient residence times during increasingly frequent droughts. Land management decisions must consider the nuanced regional and seasonal changes identified in this review (realized and predicted). Such knowledge is critical to increasing international cooperation and accelerating action toward the United Nations’s global sustainability goals and the specific objectives of the Conference of Parties (COP) 26.
... Moreover, the rapid development of the coastal economy has greatly enhanced water eutrophication (Strokal et al., 2014;Vilmin et al., 2018;Wang et al., 2016). Water eutrophication generally corresponds to high nitrate concentrations (Rozemeijer et al., 2021), which is common in surface seawater within coastal and estuary regions (Geeraert et al., 2021;Rozemeijer et al., 2021). Therefore, we hypothesize that nitrate can undergo photolysis to generate •OH in the surface seawater to enhance the COS formation. ...
... Moreover, the rapid development of the coastal economy has greatly enhanced water eutrophication (Strokal et al., 2014;Vilmin et al., 2018;Wang et al., 2016). Water eutrophication generally corresponds to high nitrate concentrations (Rozemeijer et al., 2021), which is common in surface seawater within coastal and estuary regions (Geeraert et al., 2021;Rozemeijer et al., 2021). Therefore, we hypothesize that nitrate can undergo photolysis to generate •OH in the surface seawater to enhance the COS formation. ...
Carbonyl sulfide (COS) plays an important role in the sulfur cycle and climate change. Yet, much remains unknown about the photochemical mechanisms of COS in nutrient‐rich seawater. We measured the photochemical production rates of COS in the surface seawater of the Indian Ocean under sunlight irradiation. The photochemical production of COS was mainly initiated by ultraviolet (UV) radiation with UVA contributing approximately 68% to the total COS production. Using cysteine, a typical proxy of dissolved organic sulfur, the effect of enhanced nitrate concentration on COS formation was conducted in authentic seawater during simulated sunlight irradiation, indicating the enhancement of the COS formation with increasing nitrate concentrations. This result revealed that the generation of hydroxyl radical with nitrate photolysis plays a key role in the COS formation process. These findings improve our understanding of the marine COS photoproduction cycle and the impact of nitrate on the COS photochemical production in surface seawater.
... While all of these processes occur during normal river flow, the largest fluxes of nitrogen from the catchment to the sea occurs during major storms (Gao et al., 2018;Koschorreck and Darwich, 2003;Rozemeijer et al., 2021). During major storms, there is generally higher soil erosion resulting in higher suspended particulate matter (SPM) in the river channel (Baborowski et al., 2004;Chen et al., 2018b). ...
... However, during storms, sediment from these wetlands can be resuspended, releasing the transformed nutrients into the water column and hence fluxed through the estuary to the coast (Chen et al., 2018a;Chen et al., 2018b). An important effect of climate change is that there are more frequent extreme weather events, including larger storms (Annamalai and Liu, 2005;Rozemeijer et al., 2021). These general changes increase the importance of understanding in detail the effects of major storms on anthropogenic nitrogen processes and fluxes into the river catchment and through the estuarine system discharging into the ecologically vulnerable coastal areas. ...
An important consequence of storms in river-estuary systems is major changes in hydrology and nutrients being fluxed from the land to the coastal ocean. However, the impacts of storms on the nature and amount of dissolved inorganic nitrogen (DIN) in the river-estuary continuum are poorly understood. In this study, two week’s continuous observations on two lower riverine fixed stations and an estuarine fixed station in the Jiulong River (SE China) were carried out during a complete storm event in June 10th to 23rd 2019. Suspended particulate matter (SPM), nitrogen species and their isotopic ratios, nitrifying and denitrifying functional genes were measured. The increased river discharge caused the freshwater-brackish water boundary to move downstream and altered the pattern of particle distribution and the location of the estuarine turbidity maximum. The increased river SPM and inorganic nitrogen was associated with watershed soil erosion, sediment scour and land use. Both in the river and estuary, the peak concentration of ammonium arrived faster than nitrate. Apart from river inputs, there was an additional increase of 40 ± 8% of DIN supplied within the tidal river and estuary. The additional DIN mostly came from resuspended sediments and catchment runoff, while increased nitrate also came from soil and ground waters, increased nitrification and decreased denitrification in the estuary. These results suggest that during baseflow conditions the wetlands in the upper estuary acts as a temporary nutrient trap and biogeochemical incubator, while in storms the transformed pollutant N was fluxed from the river-estuary continuum to the adjacent coastal areas.
... The study area has a long history of intense anthropogenic modification, and consequently only a small number of water bodies can be considered to be in a (near) natural state and good water quality is still severely lacking (European Environment Agency, 2018;Nijboer et al., 2004). Moreover, aquatic ecosystems in the study area experienced increasing and more variable temperatures and precipitation as a result of climate change (Rozemeijer et al., 2021). Nutrients loads decreased in the 1980s and 1990s as a result of legislation, but have remained relatively stable since 2000 (Rozemeijer et al., 2014;van Puijenbroek et al., 2014). ...
... Moreover, when these disturbances combine, the river ecosystems become more vulnerable. Adverse effects can be seen from the headwaters down to the outlets (Rozemeijer et al. 2021). These effects are significant for downstream ecosystems, such as the wetlands that depend on the streamflow inputs. ...
... losses in biodiversity, ecosystem degradation, harmful algae blooms and oxygen deficiency in bottom waters) seem to be exacerbated by synergies with other pressures, including over fishing, coastal development and climate-driven increases in sea surface temperature, ocean acidification and coastal discharge. In fact, climate change will affect nutrient inputs and behaviour and will probably exacerbate eutrophication and its associated negative impacts (Statham, 2012;Malone and Newton, 2020;Rozemeijer et al., 2021). However, the link between climate change and eutrophication is complex and is mainly related to modifications to temperature, wind patterns, the hydrological cycle, and sea level rise, resulting to inundation of freshwater systems, changes in stratification, flushing times and phytoplankton productivity, increased coastal storm activity, changes in species and ecosystem function (Statham, 2012). ...
... The loss of submerged macrophytes has become a serious ecological problem in shallow lakes worldwide (Rozemeijer et al., 2021). Zhang et al. (2017) conducted a quantitative assessment of 155 lakes around the world and found that the rate of submerged macrophyte loss (in cover and area) after 2000 was 33.6% ± 59.8% per year, especially for lakes larger than 50 km 2 , and the decreasing trend in submerged macrophytes was the most pronounced among all aquatic vegetations. ...
Introduction
Bacteria and archaea are important components in shallow lake ecosystems and are crucial for biogeochemical cycling. While the submerged macrophyte loss is widespread in shallow lakes, the effect on the bacteria and archaea in the sediment and water is not yet widely understood.
Methods
In this study, 16S rRNA gene sequencing was used to explore the bacteria and archaea in samples taken from the sediment and water in the submerged macrophyte abundant (MA) and submerged macrophyte loss (ML) areas of Caohai Lake, Guizhou, China.
Results
The results showed that the dominant bacterial phyla were Proteobacteria and Chloroflexi in the sediment; the dominant phyla were Proteobacteria, Actinobacteriota, and Bacteroidota in the water. The dominant archaea in sediment and water were the same, in the order of Crenarchaeota, Thermoplasmatota, and Halobacterota. Non-metric multidimensional scaling (NMDS) analyses showed that bacterial and archaeal community structures in the water were significantly affected by the loss of submerged macrophytes, but not by significant changes in the sediment. This suggests that the loss of submerged macrophytes has a stronger effect on the bacterial and archaeal community structures in water than in sediment. Furthermore, plant biomass (PB) was the key factor significantly influencing the bacterial community structure in water, while total nitrogen (TN) was the main factor significantly influencing the archaeal community structure in water. The loss of submerged macrophytes did not significantly affect the alpha diversity of the bacterial and archaeal communities in either the sediment or water. Based on network analyses, we found that the loss of submerged macrophytes reduced the connectivity and complexity of bacterial patterns in sediment and water. For archaea, network associations were stronger for MA network than for ML network in sediment, but network complexity for archaea in water was not significantly different between the two areas.
Discussion
This study assesses the impacts of submerged macrophyte loss on bacteria and archaea in lakes from microbial perspective, which can help to provide further theoretical basis for microbiological research and submerged macrophytes restoration in shallow lakes.
... This indicates that spring floods provide a disproportionately large CO 2 efflux from subtropical reservoirs. In the future, more intense precipitation events associated with climate change could lead to more GHG emissions from riverine reservoir systems during flooding periods (Rozemeijer et al. 2021). This highlights the necessity of considering extreme weather events in globalscale assessments of GHG emissions (Battin et al. 2023). ...
Recent studies suggest that hypolimnetic respiration may be responsible for greenhouse gas (GHG) emissions from deep reservoirs. Currently, quantitative evaluation of aerobic vs. anaerobic processes and priming (enhanced processing of organic matter due to the addition of labile carbon) in regulating GHG production and emissions across the reservoir‐downstream continuum remains largely unknown. High‐resolution, annual time‐series observations in a large, subtropical reservoir (Shuikou) experiencing seasonal hypoxia in southeast China indicate that aerobic hypolimnetic CO2 production dominated in most periods of the stratified spring/summer with higher rates at higher temperatures. In addition, anaerobic production of hypolimnetic CO2 occurred in the late stratified spring/summer period, which stimulated hypolimnetic production of CH4 and N2O. Incubation experiments showed that priming in spring enhanced both aerobic and anaerobic production of excess GHGs. A late spring flood event generated the highest daily efflux of CO2 through the flushing of GHG‐enriched hypolimnion waters. Turbine degassing contributed 59%, 93%, and 63% of annual CO2, CH4, and N2O effluxes, respectively. Moreover, annual downstream GHG emissions were similar to those in the transition/lacustrine zone of the Shuikou reservoir. Diurnal variation observations revealed net CO2 emissions even during algal bloom seasons. The reservoir‐downstream river continuum was a year‐round source of GHGs (218.5 ± 18.9 Gg CO2‐equivalent yr⁻¹; CO2 contributed 91%). However, the loss of oxygen also leads to increased production and storage of recalcitrant dissolved organic carbon (RDOC). Thus, identifying mechanisms controlling both GHG emissions and RDOC production is crucial to constrain the carbon neutrality issue of hydroelectric reservoirs in the context of climate change mitigation strategies.
... This observation is consistent with findings from traditional microscopic identification methods . It is worth noting that HABs are more commonly observed in lentic ecosystems, often associated with a high degree of eutrophication resulting from human activities ( Ajani et al., 2013 ;Rozemeijer et al., 2021 ). The North Canal tributary in Beijing experiences more disturbances due to a higher level of urbanization compared to the other two tributaries ( Wu et al., 2020 ). ...
Harmful algal blooms (HABs) have emerged as a critical global environmental and ecological concern. Timely and accurate monitoring of the prevalent bloom-forming genera is crucial for HAB management. Conventional microscope-based methods are time-consuming, labor-intensive, and specialized expertise-dependent, often making them impractical for large-scale surveillance. Molecular methods, such as metabarcoding, provide efficient technical solutions; however, the lack of competent PCR primers and further field validation present obstacles to their wide use. Here, we successfully developed Aphanizomenon-specific primers and validated the application of environmental DNA (eDNA) metabarcoding for field-based monitoring of Aphanizomenon in 37 sites across lentic and lotic freshwater ecosystems in Beijing. The sensitivity and specificity tests of newly developed primers demonstrated high performance - comprehensive recovery of biodiversity in Aphanizomenon communities and high ratios (>95%) of Aphanizomenon sequences in datasets. We observed significant correlations between the sequence abundance derived from eDNA metabarcoding and the total cell density determined through microscopic identification across all the sampling sites, both in the spring (r = 0.8086, p < 0.0001) and summer (r = 0.7902, p < 0.0001), thus validating the utility of eDNA metabarcoding based on the newly developed primers for monitoring in the field. Further, we identified key environmental variables that were primary drivers responsible for the spatiotemporal distribution of Aphanizomenon abundance. These variables included temperature, total nitrogen, and dissolved oxygen in lentic ecosystems, and total phosphorus in lotic ecosystems. The method developed and validated here offers an accurate, efficient, and high-throughput tool for the monitoring of Aphanizomenon blooms in freshwater ecosystems.
... However, excess nutrients in water bodies can favor the massive growth of aquatic plants interfering with the desirable uses of water (eutrophication - Thomann & Mueller, 1987), can cause methemoglobinemia in infants due to the high nitrate concentration (Johnson, 2019), and can intoxicate aquatic animals by the high concentrations of NH 3 (aq) Zuffo et al., 2021). Excess nutrients in water bodies have been studied in several countries, such as Russia (Sorokovkovaa et al., 2022), Uruguay (Blanco & Letelier, 2021), the Ivory Coast (Soro et al., 2023), China , the Netherlands (Rozemeijer et al., 2021), and Brazil (Anjinho et al., 2021), but mapping the different sources of contamination remains an essential and challenging issue to technically support managers for decision-making regarding important subjects, such as the one described previously (Miller et al., 2020;Yibin et al., 2021). ...
This research aims to identify critical contamination points by nutrients, their possible origin (point and nonpoint sources), their spatial distribution, and possible attenuation by natural and anthropogenic processes. The study area is the Velhas River Basin, located in the Southeast Region of Brazil (17.0°–20.5° S; 43.5°–45.0°W). A historical series of water quality monitoring, land cover map, demographic and agricultural censuses, sewage treatment diagnostics, and local hydrographic networks were used to achieve the objectives. In addition, the regions were divided into incremental areas, enabling individualized analyses of each sub-basin. Descriptive statistics, seasonality, categorized data tests, agglomerative hierarchical cluster analysis, and principal component analysis were used. There was a significant contribution of nutrients in the most important urban agglomeration of the basin, resulting in peak concentrations measured at that place. Although the values were reduced by the mouth (650 km), the percentage of legislation violations remained high. The effects of punctual contamination were intensified by the low percentage of treated sewage in the basin, the absence of adequate treatment technologies to remove nutrients, and the disorderly urbanization. Furthermore, it was estimated that the nutrient load from animal husbandry is approximately 75% of the load from domestic effluents due to the high number of cattle in the basin and the low percentage of forests.
... The eutrophication process in rivers can be primarily attributed to an increase in nitrogen (N) and phosphorus (P) loads resulting from point and non-point sources of pollution such as agricultural runoff, river transport, and industrial discharges Jarvie et al., 2018;Sun et al., 2022). Hypoxia in water bodies caused by eutrophication increases the risk of biodiversity loss and water quality degradation, rendering the water unfit for human use (Su et al., 2020;Rozemeijer et al., 2021;Beretta-Blanco and Carrasco-Letelier, 2021). The N and P levels play a significant role in determining the flux of energy and matter in surface waters (Paerl et al., 2011;Su et al., 2017;Pandey and Yadav, 2017), which in turn influences riverine ecosystem processes. ...
... Climate change effects the rainfall cycle, and temperature increases can amplify the consequences of chemical and ecological variations on water quality. The impact of climate changes on water quality increases from groundwater via head-water streams, rivers, lakes, estuaries, and coastal water (Rozemeijer et al., 2021). A microcosm experiment on eutrophication in tropical aquatic ecosystems also found a positive relationship between temperature and chlorophyll-a concentration (Moura et al., 2017). ...
Primary production is a key feature for the functioning of aquatic ecosystems. The trophic state of the streams reflects this primary production and is influenced by local limnological variables and level of integrity of the watershed. Thus, in this study, habitat integrity index (HII) and physical, chemical, and biological parameters of tropical streams were sampled in two sub-basins to understand the functioning of these ecosystems. We hypothesized that the variables association to the environmental integrity should determine the primary production in the streams. Because of the similar land use in the sub-basins (ex.: agriculture and livestock) they will show similar limnological variables. To identify how the streams differed in relation to their limnological characterization and the HII, we performed a Principal Component Analysis (PCA). The association between variables was assessed by Pearson's correlation analysis. To identify the difference between the two basins, a Student's Test was performed. The best predictors of primary production were determined using a multiple regression analysis with the Akaike selection criteria. The concentration of chlorophyll-a in the surface water indicated that the tropical streams sampled have, in general, low concentrations of nutrients, except for some more urban points. The variables that most differed among streams were blue-green cells/ml, pH, conductivity, and width of the riparian forest. Only redox potential and pH differed between the two watersheds. Temperature, blue-green cells/ml and width of the riparian forest were the variables that best predicted the phytoplankton primary production of watercourses in both watersheds. In this study we reinforce the importance of temperature in aquatic productivity, even more present in the face of climate change, which, added to deforestation, increases the surface area of sunlight in water courses, increases primary productivity and the eutrophication process.Keywords: blue-green algae; chemical variables; chlorophyll-a; HII; phytoplankton.
... This can temporarily decrease pollutant mobilization and delivery and concentrations in streams and rivers 42 . Although groundwater inputs of nutrients, salt and bedrock-derived constituents might remain similar during drought in absolute terms 60,61 , their relative influence on surface water quality might increase when surface runoff is low 59,62,63 . In most cases, a larger relative groundwater contribution results in better water quality; however, in areas with, for example, nutrient-rich or saline groundwater, the river water quality can deteriorate. ...
Climate change and extreme weather events (such as droughts, heatwaves, rainstorms and floods) pose serious challenges for water management, in terms of both water resources availability and water quality. However, the responses and mechanisms of river water quality under more frequent and intense hydroclimatic extremes are not well understood. In this Review, we assess the impacts of hydroclimatic extremes and multidecadal climate change on a wide range of water quality constituents to identify the key responses and driving mechanisms. Comparison of 965 case studies indicates that river water quality generally deteriorates under droughts and heatwaves (68% of compiled cases), rainstorms and floods (51%) and under long-term climate change (56%). Also improvements or mixed responses are reported owing to counteracting mechanisms, for example, increased pollutant mobilization versus dilution during flood events. River water quality responses under multidecadal climate change are driven by hydrological alterations, rises in water and soil temperatures and interactions among hydroclimatic, land use and human drivers. These complex interactions synergistically influence the sources, transport and transformation of all water quality constituents. Future research must target tools, techniques and models that support the design of robust water quality management strategies, in a world that is facing more frequent and severe hydroclimatic extremes.
... Excess N loading has resulted in the cultural eutrophication of rivers and reduced the biodiversity and ability of aquatic ecosystems to provide valuable services (Rozemeijer et al., 2021). This is why nutrient concentrations, such as NO 3 − , were included in the substances to be monitored in surface waters, as indicators of their ecological status under the EU Water Framework Directive (WFD) 2000/60/EC. ...
The Pinios River Basin (PRB) is the most intensively cultivated area in Greece, which hosts numerous industries and other anthropogenic activities. The analysis of water samples collected monthly for ~1 ½ years in eight monitoring sites in the PRB revealed nitrate pollution of organic origin extending from upstream to downstream and occurring throughout the year, masking the signal from the application of synthetic fertilizers. Nitrate concentrations reached up to 3.6 mg/l as NO3--N, without exceeding the drinking water threshold of ~11.0 mg/l (as NO3--N). However, the water quality status was "poor" or "bad" in ~50 % of the samples based on a local index, which considers the potential impact of nitrate on aquatic biological communities. The δ15Ν-ΝΟ3- and δ18O-NO3- values ranged from +4.4 ‰ to +20.3 ‰ and from -0.5 ‰ to +14.4 ‰, respectively. The application of a Bayesian model showed that the proportional contribution of organic pollution from industries, animal breeding facilities and manure fertilizers exceeded 70 % in most river sites with an overall uncertainty of ~0.3 (UI90 index). The δ18O-NO3- and its relationship with δ18O-H2O revealed N-cycling and mixing processes, which were difficult to identify apart from the uptake of nutrients by phytoplankton during the growing season and metabolic activities. The strong correlation of δ15Ν-ΝΟ3- values with a Land Use Index (LUI) and a Point Source Index (PSI) highlighted not only the role of non-point nitrate sources but also of point sources of nitrate pollution on water quality degradation, which are usually overlooked. The nitrification of organic wastes is the dominant nitrate source in most rivers in Europe. The systematic monitoring of rivers for nitrate isotopes will help improve the understanding of N-cycling and the impact of these pollutants on ecosystems and better inform policies for protection measures so to achieve good ecological status.
... Eutrophication of surface water bodies is a severe environmental issue globally (Balasuriya et al. 2022;Sun et al. 2022;Zhou et al. 2022). The occurrence of eutrophication in water bodies not only can cause the harmful algal blooms, bottom water hypoxia, water quality deterioration, biodiversity loss, and ecosystem degradation but also can give rise to the disruption of drinking water supplies and the closure of commercial fisheries Le Moal et al. 2019;Mackay et al. 2022;Rozemeijer et al. 2021). A lot of researchers have found that phosphorus (P) is a key limiting factor causing eutrophication in freshwater bodies (Determan et al. 2021;Schindler 1977;Schindler et al. 2016). ...
The use of in situ active capping to control phosphorus release from sediment has attracted more and more attentions in recent years. It is important to identify the effect of capping mode on the control of phosphorus release from sediment by the in situ active capping method. In this study, the impact of capping mode on the restraint of phosphorus migration from sediment into overlying water (OW) by lanthanum hydroxide (LH) was studied. Under no suspended particulate matter (SPM) deposition condition, LH capping effectively restrained the liberation of endogenous phosphorus into OW during anoxia, and the inactivation of diffusive gradient in thin film-unstable phosphorus (UPDGT) and mobile phosphorus (PMobile) in the topmost sediment served as a significant role in the restraint of endogenous phosphorus migration into OW by LH capping. Under no SPM deposition, although the transformation of capping mode from the single high dose capping to the multiple smaller doses capping had a certain negative impact on the restraint efficiency of endogenous phosphorus liberation to OW by LH in the early period of application, it increased the stability of phosphorus in the static layer in the later period of application. Under SPM deposition condition, LH capping had the capability to mitigate the risk of endogenous phosphorus liberation into OW under anoxia conditions, and the inactivation of UPDGT and PMobile in the topmost sediment was a significant mechanism for the control of sediment phosphorus liberation into OW by LH capping. Under SPM deposition condition, the change in the covering mode from the one-time high dose covering to the multiple smaller doses covering decreased the efficiency of LH to limit the endogenous phosphorus transport into OW in the early period of application, but it increased the performance of LH to restrain the sedimentary P liberation during the later period of application. The results of this work suggest that the multiple LH capping is a promising approach for controlling the internal phosphorus loading in freshwater bodies where SPM deposition often occurs in the long run.
... Eutrophication, which is manifested by the proliferation of algae and the disappearance of underwater vegetation, is an inevitable issue in global lake ecosystems (Rozemeijer et al., 2021;Zhang et al., 2016). Algae and submerged macrophytes exhibit significant differences in terms of their morphology, growth patterns, rate of decay, and other aspects, which leads to distinct environmental and management challenges Zhang et al., 2020). ...
Microorganisms play a crucial role in the biogeochemical processes of Dissolved Organic Matter (DOM), and the properties of DOM also significantly influence changes in microbial community characteristics. This interdependent relationship is vital for the flow of matter and energy within aquatic ecosystems. The presence, growth state, and community characteristics of submerged macrophytes determine the susceptibility of lakes to eutrophication, and restoring a healthy submerged macrophyte community is an effective way to address this issue. However, the transition from eutrophic lakes dominated by planktic algae to medium or low trophic lakes dominated by submerged macrophytes involves significant changes. Changes in aquatic vegetation have greatly affected the source, composition, and bioavailability of DOM. The adsorption and fixation functions of submerged macrophytes determine the migration and storage of DOM and other substances from water to sediment. Submerged macrophytes regulate the characteristics and distribution of microbial communities by controlling the distribution of carbon sources and nutrients in the lake. They further affect the characteristics of the microbial community in the lake environment through their unique epiphytic microorganisms. The unique process of submerged macrophyte recession or restoration can alter the DOM-microbial interaction pattern in lakes through its dual effects on DOM and microbial commu-----nities, ultimately changing the stability of carbon and mineralization pathways in lakes, such as the release of methane and other greenhouse gases. This review provides a fresh perspective on the dynamic changes of DOM and the role of the microbiome in the future of lake ecosystems.
... In recent years, due to human intervention, the degree of algal bloom has been increasing (Khan and Ansari, 2005;Le Moal et al., 2019;Serrano et al., 2017), and the aggravation of lake eutrophication has seriously affected the safety of water use. As shown in Fig. 1, human activities have led to an increase in water nutrient levels (Gill and Malamud, 2017;Le Moal et al., 2019;Rozemeijer et al., 2021), algal blooms (Huisman et al., 2018b), deterioration of water quality, and a decrease in dissolved oxygen content in water bodies (Hader et al., 2020;Liang et al., 2021). This further leads to widespread death of aquatic animals (mainly fish) due to the lack of oxygen (García, 2021), resulting in an increase in turbidity of water bodies, a significant decrease in its transparency, and a disturbance of aquatic ecosystems. ...
The issue of eutrophication of water bodies has attracted worldwide attention. Ecological restoration is a promising method to prevent and control eutrophic water bodies. Submerged macrophytes are widely used in the restoration processes. It can not only provide abundant food and habitat for zooplankton, but also inhibit the growth of algae through allelopathy or nutrient competition. This article provides a comprehensive review on research status on the remediation of eutrophic water by submerged macrophytes, with emphasis on the main affecting factors for their growth, including nutrients, light, water depth, sediment, temperature, biochar, transparency, and water flow. The optimum growth conditions of submerged macrophytes are further analyzed to provide guide for further studies and rear applications on the remediation of eutrophic water by submerged macrophytes.
... For instance, in the United States (U.S.) annual average precipitation has increased by 4% since 1901, yet the frequency and intensity of heavy precipitation events has increased more than 20% in the Midwest and Great Plains regions (Easterling et al 2017, Hayhoe et al 2018. In Europe and Canada, current and future N losses are linked to increased precipitation and temperature changes (Jabloun et al 2015, He et al 2018, Rozemeijer et al 2021. Moreover, years with low precipitation or drought enable the accumulation of NO 3 in soil that is 'flushed' in the subsequent year, potentially causing above-average NO 3 losses (Murphy et al 2014). ...
Nitrate (NO3) leaching from agriculture represents the primary source of groundwater contamination and freshwater ecosystem degradation. At the field level, NO3 leaching is highly variable due to interactions among soil, weather and crop management factors, but the relative effects of these drivers have not been quantified on a global scale. Using a global database of 82 field studies in temperate rainfed cereal crops with 961 observations, our objectives were to (a) quantify the relative importance of environmental and management variables to identify key leverage points for NO3 mitigation and (b) determine associated changes in crop productivity and potential tradeoffs for high and low NO3 loss scenarios. Machine learning algorithms (XGboost) and feature importance analysis showed that the amount and intensity of rainfall explained the most variability in NO3 leaching (up to 24 kg N ha−1), followed by nitrogen (N) fertilizer rate and crop N removal. In contrast, other soil and management variables such as soil texture, crop type, tillage and N source, timing and placement had less importance. To reduce N losses from global agriculture under changing weather and climatic conditions, these results highlight the need for better targeting and increased adoption of science-based, locally adapted management practices for improving N use efficiency. Future policy discussions should support this transition through different instruments while also promoting more advanced weather prediction analytics, especially in areas susceptible to extreme climatic variation.
... Furthermore, because groundwater-surface water interactions can be the important delivery pathway of chemicals, based on the end-member hydrochemistry data of groundwater or surface water, our results of varying water interchange amounts can be used to estimate the mass flux of anthropogenic pollutants (such as nutrient and heavy metals) transported between aquifer and surface water bodies (lake and river) in different seasons or years. Meanwhile, the conclusion of larger water interchange amount induced by the rainy year can be used to explain reported phenomenon that nearshore water pollution is more serious under rainy climate (Chen, 2012;Deng et al., 2014;Rozemeijer et al., 2021). ...
For areas possessing both regional-scale floodplain lakes and complex river system, the allocation pattern of water interchange between the groundwater and the lakes and rivers, as well as its temporal variations under year-scale climate changes, are important issues in regard to water resources and ecology environment but are rarely revealed. This study presented a numerical groundwater modeling of the Poyang Lake area to reveal the difference of the temporal variation patterns of the groundwater-lake water interchange and that of the groundwater-river water interchange, and to assess the potential effects of year-scale climate on the temporal-spatial variability of water interchange and on the allocation pattern of the net groundwater discharges into rivers and lake. It is found that the monthly groundwater discharge into surface water exhibits significant temporal variability, which reveals an inverse correlation between monthly groundwater discharge and lake water levels and precipitation amounts. Rainy months can lead to groundwater recharge from the Poyang Lake. Our simulated results reveal that, in the dry year of 2018, the variable monthly groundwater discharge into Poyang Lake and the monthly groundwater recharge from Poyang Lake were 0.97–9.67 × 10⁸ m³/month and 0.07–2.54 × 10⁸ m³/month, respectively. Additionally, the annual water interchange amount between groundwater and the Poyang Lake was 9.44 × 10⁸ m³/year, and the annual net groundwater discharge into Poyang Lake was 6.76 × 10⁸ m³/year. However, the hydraulic interaction between groundwater and the five rivers only features groundwater discharge into rivers with variable monthly groundwater discharge into the five rivers of 0.20–0.72 × 10⁸ m³/month and an annual total groundwater discharge amount of 5.32 × 10⁸ m³/year in 2018. Additionally, our water interchange results of the rainy year of 2010 indicate that the annual water interchange amount between groundwater and the Poyang Lake was 22.74×10⁸ m³/year, the annual net groundwater discharge into the Poyang Lake was 1.26×10⁸ m³/year, and the annual groundwater discharge into the five rivers was 8.10 × 10⁸ m³/year. These comparisons between the results of the rainy year of 2010 and dry year of 2018 can reveal the effects of the year-scale climate on water exchange between groundwater and surface water and imply that a rainy year can increase the total water interchange amount but decrease the total net groundwater discharge into surface water and that groundwater is more likely to discharge into rivers during a rainy year. Furthermore, it is found that a rainy year can significantly alter the spatial distribution of the water interchange between groundwater and lake water and that the backward particle tracking simulation could be helpful in regard to identifying the spatial distribution of water exchange between groundwater and regional-scale lake. These findings can contribute to a deeper understanding of climate effects on the spatial-temporal variability of water interchange between groundwater and surface water in regional floodplain lake areas and provide supportive information for the evaluation of local water resources and the estimation of pollutant transportation.
... Such intermittent rivers are today a matter of particular concern since they represent half of the global river network and they are complex socio-ecological systems [17]. They undergo erratic flow regimes through alternate dry and wet periods with intense flood events, making them highly sensitive to contaminants such as trace metals [16], particularly with increasing anthropogenic pressure and changes in climate conditions [18,19]. ...
River water quality is particularly of concern in semi-arid countries with limited water resources. Increasing anthropogenic activities can lead to the accumulation of trace metals (TM) in bottom sediments, which is a specific storage compartment. The present study aimed to investigate the geochemistry of trace metals (As, Cd, Co, Cr, Cu, Ni, Pb, Zn) and of some physico-chemical parameters in bottom sediments from the Sebou basin, which represents 1/3 of the surface water resources of Morocco. The order of abundance of the metals was Zn > Cr > Cu > Ni > Pb > Co > As > Cd. A major fingerprint of weathering on metal concentration, and point and non-point anthropogenic sources were highlighted. The origin and intensity of the contamination were determined using a combination of geochemical indicators. The contamination was on the whole moderate, with Cr, Zn, Cu, and Pb as the most enriched metals, especially at the A1, S3, and S4 stations located downstream of Fez city, well known for its intensive industrial and tannery activities. A multi-variate analysis evidenced the strong link between natural elements such as Co with clays and Fe oxides, and As with Ca, whereas Cd, Cu, Cr, Ni, Pb, Zn, partly originating from anthropogenic activities (industrial and domestic waste, agricultural inputs), were linked to phosphorus, oxides, carbonates, and/or POC, indicating their anthropic source and/or control by sediment compounds. Cadmium, Pb, and Cu were the most available metals. Finally, in addition to Cd, Pb and Zn were identified as hazardous metals in sediments as evidenced by the positive relationship between the proportion of the labile fraction and the enrichment factor revealing anthropogenic inputs.
... Sri Lanka is the center of an important commercial port. Most coastal waters are affected by pollution and eutrophication (Jiang et al., 2019;Rozemeijer et al., 2021). Simultaneously, SA is influenced by the East Indian Coastal Current and Bay of Bengal Runoffs, which has resulted in relatively rich nutrients that have made the area suitable for phytoplankton growth. ...
Comprising one of the major carbon pools on Earth, marine dissolved organic matter (DOM) plays an essential role in global carbon dynamics. The objective of this study was to better characterize DOM in the eastern Indian Ocean. To better understand the underlying mechanisms, seawater samples were collected in October and November of 2020 from sampling stations in three subregions: the mouth of the Bay of Bengal, Southern Sri Lanka, and Western Sumatra. We calculated and evaluated different hydrological parameters and organic carbon concentrations. In addition, we used excitation emission matrix (EEM) spectroscopy combined with parallel factor analysis (PARAFAC) to analyze the natural water samples directly. Parameters associated with chromophoric DOM did not behave conservatively in the study areas as a result of biogeochemical processes. We further evaluated the sources and processing of DOM in the eastern Indian Ocean by determining four fluorescence indices (the fluorescence index, the biological index, the humification index, and the freshness index β/α). Based on EEM-PARAFAC, we identified six components (five fluorophores) using the peak picking technique. Commonly occurring fluorophores were present within the sample set: peak A (humic-like), peak B (protein-like), peak C (humic-like), and peak T (tryptophan-like). The fluorescence intensity levels of the protein-like components (peaks B and T) were highest in the surface ocean and decreased with depth. In contrast, the ratio of the two humic-like components (peaks A and C) remained in a relatively narrow range in the bathypelagic layer compared to the surface layer, which indicates a relatively constant composition of humic-like fluorophores in the deep layer.
... The eutrophication of large and small rivers is a current problem in Ukraine [5][6][7]. This is especially true for rivers that flow through cities, especially in densely populated areas [8]. Flora and fauna suffer from eutrophication, such rivers silt their banks and may have an unsatisfactory aesthetic appearance. ...
The process of eutrophication has a negative impact on the water body (flora and fauna) and decreases its aesthetic and recreational values. In this work, we propose to combine chemical and physical methods for the restoration of rivers and lakes in Ukraine with the help of regionally occurring carbonates and quartz-glauconite sand. Experimental studies have shown that their use should have a high environmental effect on the improvement of the river water quality, that is, after the use of the Fe-coagulant. The addition of this coagulant can removal prostates and
organic matter but may reduce the water pH. Therefore, to prevent stress recurrence in the aquatic ecosystem after adding natural calcium carbonate to water, its optimal doses were determined experimentally. It was found that the optimal application dose depended on the initial pH value of water and its mineralization. Experimental studies of the physical and chemical properties of quartz-glauconite sands have shown high values of the filtration coefficient, the capability of increasing the water pH value and improving the water reducing properties. These properties of natural reactive materials (limestones and quartz-glauconite sand) were used to design and construct
earth structures for river rehabilitation. Reactive materials can be placed on the river banks, parallel to the direction of the water flow, or as permeable reaction barriers constructed perpendicular to the river flow direction. After the rehabilitation works are completed, the area on the river banks may be adapted as a public space for the local residents.
... Climate change can also stimulate the eutrophication process (Rozemeijer et al., 2021) which can have a serious effect on reservoir ecosystem services. Firstly, alterations in the hydrological cycle can result in more pollutants entering the water by erosion and other processes (Dunn et al., 2012), and secondly, higher water temperatures stimulate the development of autotrophic organisms such as harmful algae blooms (HABs) (Chapra et al., 2017); many drinking watersuppling reservoirs have been affected by HABs, including the Sulejów reservoir located in central Poland (Tarczyńska et al., 2001;Mankiewicz-Boczek et al., 2016). ...
River system retentiveness must be enhanced to increase multidimensional environmental sustainability and thus ameliorate the effects of climate change and the occurrence of extreme hydrological events. The aim of the article is to demonstrate how ecohydrological Nature-Based Solutions can be combined with conventional infrastructure to improve WBSRCE benefits (Water, Biodiversity, ecosystem Services, Resilience, Culture, Education) by taking a holistic approach to multifunctional reservoir design. The paper proposes a new form of lateral reservoir, which is built without disturbing the meandering river and is supplied with good quality water through a monitoring and regulatory system; its design is based on thorough analysis of hydrological pulses and suspended matter and nutrients fluxes. The regulatory system also includes an innovative Sequential Sedimentation and Biofiltration System. Lateral reservoirs increase water retentiveness in the river valley by lifting ground water level and restoring surrounding wetlands, thus enhancing biodiversity, ecosystem services for society and the resilience of the river system to climate change. An integrative understanding of the interplay between hydrology and biocenosis can be used to enhance river system sustainability potential (WBSR) and harmonise societal needs with biosphere sustainability through culture and education (CE).
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... Dutch households are relatively water efficient compared to other industrialised countries [61]. More recently, however, the frequency and length of heatwaves have substantially increased, leading to environmental degradation [62], lower pressure, sometimes discolouration at the tap [63,64], and freshwater resources-particularly groundwater resources-are under pressure [65],. These developments are paving the way for the smallscale introduction of DWM as a means to enhance domestic water conservation. ...
In response to droughts, various media campaigns and water-saving instructions are released. However, these often only have temporary water conservation effects. A promising development in this regard is Digital Water Meters (DWM), which can provide near real-time water-use feedback. Despite extensive DWM experience in some water-stressed regions, a profound understanding of the initial attitude towards DWM and message-tailoring opportunities are rarely empirically explored. This study aims to obtain insights into the attitude towards the introduction of DWM and explore opportunities for message tailoring, a topic of extra relevance as we may be on the threshold of a large-scale DWM implementation in many world regions. Messages tailored to (i) normative beliefs and attitudes on drinking water, (ii) water-use activity and (iii) phase of decision-making, seem particularly compatible with DWM. Through a survey (n = 1037) in the Netherlands, we observe that 93% of respondents have no objections if their utility invests in DWM and that 78% would accept a (free) DWM because of improved leakage detection, lower costs and environmental considerations. Finally, instead of sociodemographic factors, we observe that an attitude-based customer segmentation approach is an especially useful predictor of respondent’s motivation to endorse DWM and forms a promising basis for water conservation message-tailoring strategies.
... The excessive N and P enrichment of water bodies cause nutrient imbalance, induces bloom formation on the water surface, and anoxic conditions inside the water (Carpenter, 2005;Häder et al., 2020;Liang et al., 2021). The main eutrophication causes include diffuse sources such as agricultural areas, sewage treatment plants (STPs) as the point sources, and natural environment particularly climate change (Gill and Malamud, 2017;Le Moal et al., 2019;Rozemeijer et al., 2021). The freshwater ecosystems (rivers and lakes) are mainly utilized for drinking, sanitation, agricultural, and industrial purposes, which in turn discharge a huge amount of waste (containing N and P) into these water bodies (Häder et al., 2020;Srivastava et al., 2016). ...
Eutrophication is a global concern that has severely deteriorated the aquatic ecosystems. This phenomenon has impacted the freshwater bodies (such as lakes and rivers) across the world due to the nutrients (mainly N and P) arising from point and non-point pollution sources. Nutrient enrichment induces cyanobacteria formation, hypoxia, and release of bloom toxins, causing their accumulation in aquatic organisms and humans. Preventing the use of chemicals (such as fertilizers) at the source can avoid nutrient release in the run off streams, thus controlling non-point pollution. While point source pollutants can be effectively controlled at the sewage treatment plants. Although freshwater eutrophication managements have been widely discussed, a systematic eutrophication characterization of lakes and rivers worldwide, with their effective, economically feasible, eco-friendly, and beneficial bio-treatments is still scarce. Hence, in this review a complete eutrophication-based characterization of lakes and rivers all over the world is provided. Different cost-effective and efficient bio-remediations to control point and non-point pollution are discussed, additionally with a comparative account for the selection of a suitable microbe and remediation approach. A combined point and non-point pollution management can eradicate eutrophication.
... Variations in regional temperature and precipitation have the potential to transform the water balance of the most varied regions by changing the distribution of water along the different compartments of the hydrological cycle and modifying the amount of water that reaches the surface, infiltrates into the groundwater system, returns to the atmosphere through evaporation and transpiration processes, becomes snow or ice, runs off the land or becomes base flow to surface water bodies (Gemitzi et al., 2017;Kundzewicz et al. 2008;Liu, 2011;Mechal et al. 2015;Meixner et al. 2016;Montenegro & Ragab, 2012;Parajuli, 2010;Tanaka et al. 2006;Tundisi & Tundisi, 2014;Zagonari, 2010). Besides the quantitative variations in the water cycle, water quality issues may also arise in the regions affected by climate change due to the increase in the number of extreme events such as wildfires, heat waves, floods and droughts (Balocchi et al. 2020;Fan & Shibata, 2015;Hohner et al. 2019;Loiselle et al. 2020;Rozemeijer et al. 2021;Smith et al. 2011). ...
Climate change can affect directly the hydrological cycle and influence groundwater availability due to the direct or indirect impact on recharge and discharge processes. The present investigation focuses on groundwater recharge processes in a fluvial-deltaic aquifer in the northern part of the Rio de Janeiro state (Brazil), a region that relies on groundwater resources and where meteorological data indicate a shift from tropical humid climatic conditions to semiarid. The main objective is to understand how groundwater resources respond to the consequences of climate change on groundwater recharge, in order to improve groundwater management practices and guarantee quantitative and qualitative good status. Climate models’ data and projections were used as a tool to provide a better understanding of how climate change can modify the dynamics in the studied groundwater system. The present climate indices for extreme temperature and precipitation (1961–1990) were examined in order to establish the current climatology for the study area, and the Thornthwaite−Mather hydrometeorological balance (TMHB) was used to calculate inputs to the aquifer. Projections for annual rainfall and air temperature for the period 2041–2070 obtained from Eta5km_HadGEM2-ES outputs for the Intergovernmental Panel on Climate Change scenarios RCP4.5 and RCP8.5 were used to estimate recharge to the aquifer using the hydrological code Visual Balan v2.0. Results revealed a tendency to air temperature increase and decrease in precipitation rate for the period of study. Consequently, there was a reduction of recharge in both IPCC scenarios used for the estimation, indicating a decrease in the groundwater resources stored in the region. These results place new challenges to guarantee sustainable groundwater management and the achievement of new aquifer system equilibrium to adapt to climate change impacts.
The Kanogawa River runs from Amagi Mountains in the middle of Izu Peninsula toward to the foot of Mt. Fuji and discharges into Suruga Bay. The length of the river is 46 km, and the annual mean rainfall of the catchment scale amounts to 2,830 mm at the Yugashima observation site. The quality of river water was examined using public data sources spanning the nearly 30 years from 1990 to 2019. A decrease in organic compound pollution was shown by an apparent change in BOD concentration for all the examined observation points from upstream to downstream. The concentrations of COD and SS also supported this tendency. Other examined parameters such as pH and DO did not support this decrease and they likely came from biogeochemical activities in the river water. The reason for the improvement of water quality can be ascribable to the development of sewage treatment systems in the mid- and downstream catchment throughout the examined 30 years.
This study investigates the impact of environmental factors on benthic Chlorophyll-a (Chl-a) concentrations in river ecosystems, focusing on the Jhelum River Basin (JRB). It assesses the influence of hydro-chemical variables on Chl-a levels and trophic status across 59 sites spanning upstream, midstream, and downstream sections. The trophic status based on the mean and maximum concentration of Chl-a at various sites reveals the oligotrophic (76%) to mesotrophic (24%) nature of the JRB. Whereas, the concentration of total phosphorus (TP) revealed the mesotrophic (42%) to eutrophic (58%) nature of the JRB. Hierarchical cluster analysis (HCA) of data sets resulted in the formation of three distinct clusters. Cluster I was dominated by upstream sites (72%), cluster II was dominated by mid and downstream sites (71%), while cluster III was represented by main river and downstream sites (84%). Multiple linear regression (MLR) model (p˂0.05) revealed TP (30-554 µg/l) and dissolved oxygen (DO) (5–13 mg/l) as major parameters influencing Chl-a content. MLR also highlighted that ammoniacal nitrogen (NH3–N), nitrite nitrogen (NO2-N), electrical conductivity (EC), current velocity (V), discharge (D) and water temperature have significant relation (p˂0.05) with Chl-a concentration but differ seasonally. Water quality index (WQI) on the basis of NH3-N, TP, DO, Chl-a and Faecal Coliform (FC) highlighted excellent to good for majority of upstream sites and poor to water unsuitable for all downstream sites respectively. The study offers clear signs of nutrient enrichment and increasing algal biomass downstream of JRB.
Eutrophication of water bodies is analysed as a global process. The volumes of globally increasing use of nitrogen and phosphorus are demonstrated, with the dispersion of these elements leading to increased nutrient contents in lakes and rivers. Results of original studies on remote lakes in the Arctic zone indicate that the content of nutrients in these lakes has increased over the past decades. Concentrations of nitrogen, phosphorus and organic matter in lake waters tend to increase in the absence of anthropogenic effects. Simultaneously, the silicon concentrations were found to decrease because of the consumption by diatoms. Low concentrations of bioavailable nutrients confirm that these nutrients are rapidly spent in the production processes of ecosystems. The calculated trophic state index (according to R. Carlson) indicates that the number of oligotrophic lakes in the forest tundra zone decreased by 50% by 2010–2018, and these lakes are absent from the northern taiga zone. Temperature increase and climate warming in the Arctic zone first caused the increase in the contents of nutrients in the lakes and their trophic states.
High-quality water is rare in arid and semi-arid regions like those found in the MENA countries. The hydrological cycle involves groundwater recharge, wherein water moves from the water table to the saturated zone through percolation or drainage, entering the aquifer and flowing through the vadose zone. Both natural groundwater recharge via the hydrological cycle and artificial recharge are considered mechanisms for retaining water within the subsoil. Storing water in surface reservoirs presents drawbacks, such as significant evaporation losses, the need for extensive land, sediment accumulation, structural failure risks, and susceptibility to pollution. Consequently, there is a growing interest in exploring diverse Managed Aquifer Recharge (MAR) technologies to function as extensive reservoirs, offering effective alternatives in various hydrogeological contexts. This chapter aims to elucidate the various types of AR techniques and their influence on groundwater quality, highlighting their potential as sustainable and efficient approaches in water management across diverse domains. MAR using Treated Wastewater (TWW) can be considered safe, provided that specific precautionary measures are implemented to ensure the quality of the effluent, and the discharge of Treated Wastewater is carefully regulated. This safeguards freshwater resources for both current and future generations.
Pada saat ini perubahan iklim sedang dialami secara global yang dampaknya diperkirakan akan sama seperti pandemi. Perubahan iklim terdiri dari empat faktor utama yaitu terjadinya peningkatan suhu atmosfer, perubahan pola curah hujan, peningkatan konsentrasi CO2 di atmosfer dan peningkatan kadar ozon di troposfer (O3). Dampak perubahan iklim yang biasanya diketahui adalah menurunnya ketersediaan air, sedangkan hubungannya dengan kualitas air masih kurang dipahami. Tujuan literatur review pada makalah ini adalah sebagai kumpulan referensi untuk mengetahui terdapat dampak perubahan iklim terhadap kualitas air di Daerah Aliran Sungai dan sebagai pencarian state of art untuk gap yang akan dilakukan pada penelitian selanjutnya. Pada makalah ini akan membahas mengenai pembagian iklim, Dampak Perubahan Iklim di Indonesia terhadap Sumber Daya Air, kondisi kualitas air sungai, dan ketahanan air terhadap perubahan iklim serta peraturan dan kebijakan di Indonesia mengenai pengelolaan sumberdaya air di Indonesia dan klimatologi. Metode yang digunakan dalam literatur review ini adalah menggunakan kata kunci dampak perubahan iklim pada pencarian di website jurnal seperti di Google scholar, Scopus dan Science direct dengan rentan waktu 5 sampai 10 tahun (2011 – 2021).
Rivers worldwide are under stress from eutrophication and nitrate pollution, but the ecological consequences overlap with climate change, and the resulting interactions may be unexpected and still unexplored. The Po River basin (northern Italy) is one of the most agriculturally productive and densely populated areas in Europe. It remains unclear whether the climate change impacts on the thermal and hydrological regimes are already affecting nutrient dynamics and transport to coastal areas. The present work addresses the long-term trends (1992–2020) of nitrogen and phosphorus export by investigating both the annual magnitude and the seasonal patterns and their relationship with water temperature and discharge trajectories. Despite the constant diffuse and point sources in the basin, a marked decrease (-20%) in nitrogen export, mostly as nitrate, was recorded in the last decade compared to the 1990s, while no significant downward trend was observed for phosphorus. The water temperature of the Po River has warmed, with the most pronounced signals in summer (+0.13°C/year) and autumn (+0.16°C/year), together with the strongest increase in the number of warm days (+70–80%). An extended seasonal window of warm temperatures and the persistence of low flow periods are likely to create favorable conditions for permanent nitrate removal via denitrification, resulting in a lower delivery of reactive nitrogen to the sea. The present results show that climate change-driven warming may enhance nitrogen processing by increasing respiratory river metabolism, thereby reducing export from spring to early autumn, when the risk of eutrophication in coastal zones is higher.
Macrophytes play an important role in assessing the condition of aquatic ecosystems. The aim of the study was to assess the effectiveness of cadmium uptake by frogbit (Hydrocharis morsus-ranae) for the phytoremediation of aquatic ecosystems. The study examined cadmium (Cd) uptake by frogbit grown under conditions of low and high fertilizer dose and three cadmium dose levels over three- and six-week exposure times. Cadmium uptake was found to be influenced by water reactivity, mineral nutrient abundance, and exposure time. Its accumulation in frogbit is hence a good bioindicator of cadmium pollution in water bodies. Where the plant had greater access to phosphorus, nitrogen, potassium (PNK) compounds, i.e., high fertilizer level, a higher pH level (7.6) was associated with increased cadmium uptake and decreased plant biomass. A higher PNK level was also associated with greater tolerance to cadmium, while at lower PNK levels, more efficient cadmium uptake was noted after three weeks. Hydrocharis morsus-ranae can be used for water and wastewater treatment in the final stage of phytoremediation, but in combination with other species of pleustophytes that represent different biosorption sites.
Major storms, which are increasing in frequency due to climate change, flush pollutant nutrients, including phosphorus (P), from river catchments through estuaries to the coast. Changes in P speciation alter the potential for P removal in sediments. We measured suspended particle matter (SPM), dissolved and particulate phosphorus and other physicochemical parameters at two river outlets of the Jiulong River (SE China) and a fixed station in the estuary during an entire storm (June 2019). During the storm, riverine total particulate phosphorus (TPP) more than doubled to approximately 100 μg P L⁻¹ mainly from pollutant sources, while increased soil erosion reduced the TPP:SPM ratio by 1/3. The riverine DIP increase during the storm was only moderate (approximately 25%). As the storm intensified, the fresh‐brackish water interface moved downstream. There was increased SPM and TPP flux (up to approximately 25,000 kg P d⁻¹) from resuspended surficial sediment that had been deposited during normal flow in the adjacent tidal flats and mangrove areas. These sediments had acted as microbial incubators. Reduced Fe in the resuspended sediment was converted to labile Fe oxyhydroxides in the oxic water column, which adsorbed DIP (and probably also DOP) and increased labile TPP exported downstream. During the storm, the total flux of riverine dissolved nutrients increased while the TDN:TDP ratio decreased from 43:1 to 32:1. Our study showed that estuaries are locations for temporary deposition of labile TPP during normal flow, which are flushed out during major storms, likely resulting in increased eutrophication, including encouraging harmful algal blooms in coastal zones.
2 SARS-CoV-2 has aroused drastic effects on the global economy and public health. In response to this, personal protective equipment, hand hygiene, and social distancing have been considered the most important ways to prevent the direct spread of the virus. SARS-CoV-2 would be possible survive in wastewater for a few days, leading to secondary transmission via contact with water and wastewater. Thus, the most economical and practical approaches for decentralized wastewater treatment are renewable energies such as the solar energy disinfestation process. However, as freshwater requirements increase and fossil fuels become unsustainable, renewable energy becomes more attractive for desalination applications. Solar photovoltaic, membrane-based, and electricity desalination technologies are becoming increasingly popular due to their lower energy requirements. Several aquatic environments could be benefitted from solar energy wastewater disinfection. Besides, utilizing solar energy during the day can inactivate SARS-CoV-2 to nearly 90%. However, conventional membrane-based desalination practices have also been integrated, including reverse osmosis (RO) and electrodialysis (ED). Several exciting membrane processes have been developed recently, including membrane distillation (MD), pressure-reduced osmosis (PRO), and reverse electrodialysis (RED). Such operations can produce clean and sustainable electricity from brine and impaired water, generally considered hazardous to the environment. As a result, neither PRO nor RED can produce electricity without mixing a high salinity solution (such as seawater or brine and wastewater, respectively) with a low salinity solution. Herein, we critically review the progress in applying renewable energy such as solar energy and geothermal energy for generating electricity from wastewater treatment and uniquely discuss the effects of these two types of renewable energy on SARS-CoV-2 in air and wastewater treatment. We also highlight the significant process made on the membrane processes utilizing renewable energy and research gaps from the standpoint of producing clean 3 and sustainable energy. The significant points of this review are: (1) among various types of renewable energy, solar energy and geothermal energy have been predominantly studied for wastewater treatment, (2) effects of these two types of renewable energy on SARS-CoV-2 in air and wastewater treatment are critically analyzed, and (3) the knowledge gaps and anticipated future research outlook have been consequently proposed thereof.
Little is known about the distribution and risk levels of nutrients and organic matter (OM) in the surface sediment of shallow submerged macrophyte-dominated lakes. In the current study, sixty surface sediment samples were collected from Xukou Bay, a typical submerged macrophyte-dominated zone in Lake Taihu, China. A 60-day degradation experiment of Potamogeton malaianus, a dominant species in the bay, was done in the laboratory. The results demonstrated that the ranges of total nitrogen (TN) and total phosphorus (TP), alkali-hydrolyzable nitrogen (AN), available phosphorus (AP), and OM in the surface sediment of the bay were 262.2–2,979.6 mg/kg, 41.2–728.7 mg/kg, 8.6–150.0 mg/kg, 4.4–36.4 mg/kg, and 3.7–50.2 g/kg, respectively. The spatial distributions of TN, OM, and AN concentrations showed similar trends: The highest concentrations were present in the northeastern and southwestern zones, while the TP and AP concentrations were high in the northeastern, central, and southwestern zones. The heterogeneity in the spatial distribution of nutrients and OM in the surface sediment of the bay was associated with aquatic vegetation and anthropogenic activities. The comprehensive risk index and organic nitrogen index revealed that the surface sediment was moderately, interactively contaminated by TN and TP and by organic nitrogen. TN and OM in the northeastern zone were mainly derived from endogenous residues due to the decomposition of aquatic plants, while TN in the southwestern zone was primarily derived from agricultural wastewater. Consequently, targeted measures should be implemented to reduce TN and OM in the surface sediment of macrophyte-dominated lakes.
The summer of 2018 was characterized by high temperatures and low precipitation values in the Netherlands. The drought negatively impacted different sectors, resulting in an estimated damage of 450 to 2080 million Euros. Strong regional differences were observed in the precipitation shortfall across the country, with highest deficits in the southern and eastern regions. This raised two questions: (i) have increasing global temperatures contributed to changes in meteorological and agricultural droughts as severe or worse as in 2018? And (ii) are trends in these types of droughts different for coastal and inland regions? In this paper we show that there is no trend in summer drought (Apr-Sep) near the coast. However, a trend in agricultural drought is observed for the inland region where water supply is mainly dependent on local precipitation. This trend is driven by strong trends in temperature and global radiation rather than a trend in precipitation, resulting in an overall trend in potential evapotranspiration. Climate model analyses confirm that this trend in agricultural drought can at least in part be attributed to global climate change.
Nitrate (NO3) is one of the main pollutants in agriculturally impacted groundwater systems. The availability and reactivity of electron donors control the prevalent redox conditions in aquifers and past nitrate contamination of groundwater can be ameliorated if denitrification occurs. Using aqueous geochemistry data and the stable isotope composition of dissolved nitrate (δ15N & δ18O) we found that nitrate concentrations above the WHO drinking water guideline were caused predominantly by manure and to a lesser extent by synthetic fertilizer applications and that denitrification was not a significant nitrate removal process in an aquifer in southern Germany underlying agricultural land with intensive hog farming. We also applied environmental isotopes (δ2H & δ18O, 3H/3He, 14C) linked with a lumped parameter approach to determine apparent mean transit times (MTT) of groundwater that ranged from < 5 years to > 100 years. Furthermore, we determined low reduction rates of dissolved oxygen (O2) of 0.015 1/year for first‐order kinetics. By extrapolating the O2 reduction rates beyond the apparent MTT ranges of sampled groundwater, denitrification lag times (time prior to commencement of denitrification) of approximately 114 years were determined. This suggests that it will take many decades to significantly reduce nitrate concentrations in the porous aquifer via denitrification, even if future nitrate inputs were significantly reduced.
Haunted by the past
Reducing the extent of hypoxia in the Gulf of Mexico will not be as easy as reducing agricultural nitrogen use. Van Meter et al. report that so much nitrogen from runoff has accumulated in the Mississippi River basin that, even if future agricultural nitrogen inputs are eliminated, it will still take 30 years to realize the 60% decrease in load needed to reduce eutrophication in the Gulf. This legacy effect means that a dramatic shift in land-use practices, which may not be compatible with current levels of agricultural production, will be needed to control hypoxia in the Gulf of Mexico.
Science , this issue p. 427
The relationship between antecedent flow conditions and nitrate
concentrations was explored at eight sites in the 2.9 million square kilometers
(km2) Mississippi River basin, USA. Antecedent flow conditions were
quantified as the ratio between the mean daily flow of the previous year and
the mean daily flow from the period of record (Qratio), and the Qratio was
statistically related to nitrate anomalies (the unexplained variability in
nitrate concentration after filtering out season, long-term trend, and
contemporaneous flow effects) at each site. Nitrate anomaly and Qratio were
negatively related at three of the four major tributary sites and upstream
in the Mississippi River, indicating that when mean daily streamflow during
the previous year was lower than average, nitrate concentrations were higher
than expected. The strength of these relationships increased when data were
subdivided by contemporaneous flow conditions. Five of the eight sites had
significant negative relationships (p ≤ 0.05) at high or moderately
high contemporaneous flows, suggesting nitrate that accumulates in these
basins during a drought is flushed during subsequent high flows. At half of
the sites, when mean daily flow during the previous year was 50 percent
lower than average, nitrate concentration can be from 9 to 27 percent
higher than nitrate concentrations that follow a year with average mean
daily flow. Conversely, nitrate concentration can be from 8 to 21 percent
lower than expected when flow during the previous year was 50 percent higher
than average. Previously documented for small, relatively homogenous basins,
our results suggest that relationships between antecedent flows and nitrate
concentrations are also observable at a regional scale. Relationships were
not observed (using all contemporaneous flow data together) for basins
larger than 1 million km2, suggesting that above this limit the overall
size and diversity within these basins may necessitate the use of more
complicated statistical approaches or that there may be no discernible
basin-wide relationship with antecedent flow. The relationships between
nitrate concentration and Qratio identified in this study serve as the basis
for future studies that can better define specific hydrologic processes
occurring during and after a drought (or high flow period) which influence
nitrate concentration, such as the duration or magnitude of low flows, and
the timing of low and high flows.
Large nutrient losses to groundwater and surface waters are a major drawback of the highly productive agricultural sector in The Netherlands. The resulting high nutrient concentrations in water resources threaten their ecological, industrial, and recreational functions. To mitigate eutrophication problems, legislation on nutrient application in agriculture was enforced in 1986 in The Netherlands. The objective of this study was to evaluate this manure policy by assessing the water quality status and trends in agriculture-dominated headwaters. We used datasets from 5 agricultural test catchments and from 167 existing monitoring locations in agricultural headwaters. Trend analysis for these locations showed a fast reduction of nutrient concentrations after the enforcement of the manure legislation (median slopes of -0.55 mg/l per decade for total nitrogen (N-tot) and -0.020 mg/l per decade for total phosphorus (P-tot)). Still, up to 76 % of the selected locations currently do not comply with either the environmental quality standards (EQSs) for nitrogen (N-tot) or phosphorus (P-tot). This indicates that further improvement of agricultural water quality is needed. We observed that weather-related variations in nutrient concentrations strongly influence the compliance testing results, both for individual locations and for the aggregated results at the national scale. Another important finding is that testing compliance for nutrients based on summer average concentrations may underestimate the agricultural impact on ecosystem health. The focus on summer concentrations does not account for the environmental impact of high winter loads from agricultural headwaters towards downstream water bodies.
Nitrate pollution in groundwater, which is mainly from agricultural activities, remains an international problem. It threatens the environment, economics and human health. There is a rising trend in nitrate concentrations in many UK groundwater bodies. Research has shown it can take decades for leached nitrate from the soil to discharge into groundwater and surface water due to the 'store' of nitrate and its potentially long travel time in the unsaturated and saturated zones. However, this time lag is rarely considered in current water nitrate management and policy development. The aim of this study was to develop a catchment-scale integrated numerical method to investigate the nitrate lag time in the groundwater system, and the Eden Valley, UK, was selected as a case study area. The method involves three models, namely the nitrate time bomb-a process-based model to simulate the nitrate transport in the unsaturated zone (USZ), GISGroundwater-a GISGroundwater flow model, and N-FM-a model to simulate the nitrate transport in the saturated zone. This study answers the scientific questions of when the nitrate currently in the groundwater was loaded into the unsaturated zones and eventually reached the water table; is the rising groundwater nitrate concentration in the study area caused by historic nitrate load; what caused the uneven distribution of groundwater nitrate concentration in the study area; and whether the historic peak nitrate loading has reached the water table in the area. The groundwater nitrate in the area was mainly from the 1980s to 2000s, whilst the groundwater nitrate in most of the source protection zones leached into the system during 1940s-1970s; the large and spatially variable thickness of the USZ is one of the major reasons for unevenly distributed groundwater nitrate concentrations in the study area; the peak nitrate loading around 1983 has affected most of the study area. For areas around the Bowscar, Beacon Edge, Low Plains, Nord Vue, Dale Springs, Gamblesby, Bankwood Springs, and Cliburn, the peak nitrate loading will arrive at the water table in the next 34 years; statistical analysis shows that 8.7 % of the Penrith Sandstone and 7.3 % of the St Bees Sandstone have not been affected by peak nitrate. This research can improve the scientific understanding of nitrate processes in the groundwater system and support the effective management of groundwater nitrate pollution for the study area. With a limited number of parameters, the method and models developed in this study are readily transferable to other areas.
Over the last 100 years there are have been clear precipitation trends in Europe. In winter, precipitation has increased in north-western Europe. In summer, there has been an increase along many coasts in the same area. An investigation of precipitation trends in three multi-model ensembles including both global and regional climate models shows that these models have trouble reproducing the observed trends. In many regions the observation fall outside the bandwidth of natural variability combined with model uncertainty as parametrised by the multi-model ensemble. Conversely, the ensemble mean falls outside the error margins of the observed trends in the same regions. In contrast, regional climate model experiments with observed boundary conditions show precipitation trends that are in good agreement with observations. We investigate the relative importance of the two prescribed factors: atmospheric circulation and sea surface temperature in setting the observed trend. The causes of the large trends in atmospheric circulation are not known, the lower SST trend in climate models is due to well-known problems in low-resolution ocean models. Improving the ocean models used for climate projections will therefore lead to more realistic precipitation trends.
In 2011, Lake Erie experienced the largest harmful algal bloom in its recorded history, with a peak intensity over three times greater than any previously observed bloom. Here we show that long-term trends in agricultural practices are consistent with increasing phosphorus loading to the western basin of the lake, and that these trends, coupled with meteorological conditions in spring 2011, produced record-breaking nutrient loads. An extended period of weak lake circulation then led to abnormally long residence times that incubated the bloom, and warm and quiescent conditions after bloom onset allowed algae to remain near the top of the water column and prevented flushing of nutrients from the system. We further find that all of these factors are consistent with expected future conditions. If a scientifically guided management plan to mitigate these impacts is not implemented, we can therefore expect this bloom to be a harbinger of future blooms in Lake Erie.
The linkage between land use in a catchment basin and downstream aquatic ecosystems, especially effects on algae attached to substrata or loosely aggregated in the littoral zone, represents a void in our understanding of lake systems. The occurrence of beds of metaphyton at some stream mouths and not others in Conesus Lake, NY (USA) provided an opportunity to consider the relationship between land use and phosphorus and nitrogen losses on the development of shoreline metaphyton blooms. Experiments were performed in the littoral zone of a large temperate lake to test the hypothesis that effluent high in phosphorus and nitrate from tributaries draining agricultural watersheds had a stimulatory effect on the growth of littoral metaphyton, while effluent from a forested watershed did not. The study encompassed six watersheds of varying agricultural use (60–80%) and a forested watershed (12% agriculture). For each experiment, two quadruplicate sets of plexiglass incubation chambers (height = 50 cm, interior diameter = 9.5 cm) containing native assemblages of metaphyton received lake or tributary water continuously over a 3-day lake incubation period. Growth of metaphyton incubated in lake water and in tributary water was compared and differences appeared to be related to nutrient concentrations. A statistically significant stimulatory effect was measured for the six tributaries draining agricultural watersheds but not for the forested watershed. Tributary loadings appear to stimulate metaphyton at sites where the hydrology and hydrodynamincs are suitable. A significant positive linear relationship existed between percent metaphyton cover in the littoral zone and the percent of land use in agriculture. Metaphyton abundance is impacted by land use practices and subsequent loss of nutrients from the catchment.
The strength of the North Atlantic Current (NAC) (based on sea-surface elevation slopes derived from altimeter data) is correlated with westerly winds (based on North Atlantic Oscillation [NAO] Index data over a nine year period [1992^2002] with 108 monthly values). The data time window includes the major change in climate forcing over the last 100 years (1995 to 1996). It is shown that the NAO Index can be used for early warning of system failure for the NAC. The correlation response or early warning time scale for western Europe and south England is six months. The decay scale for the NAC and Subtropical Gyre circulation is estimated as three years. Longer period altimeter elevation/circulation changes are discussed. The sea-surface temperature (SST) response of the North Sea to negative and positive NAO conditions is examined. The overall temperature response for the central North Sea to NAO index forcing, re£ecting wind induced in£ow, shelf circulation and local climate forcing, is 10.58C) are about 18C warmer than under negative conditions. In 1996 under extreme negative winter NAO conditions, the North Sea circulation stopped, conditions near the Dogger Bank became more conti-nentally in£uenced and the winter (March) temperature fell to 3.18C whereas in 1995 under NAO positive winter conditions the minimum temperature was 6.48C (February). Seasonal advance of North Atlantic and North Sea temperature is derived in relation to temperature change. Temperature change and monthly NAO Index are discussed with respect to phytoplankton blooms, chlorophyll-a measurements, ocean colour data and the anomalous north-eastern Atlantic 2002 spring/summer bloom SeaWiFS chlorophyll concentrations.
Climate change will alter freshwater ecosystems but specific effects will vary among regions and the type of water body. Here,
we give an integrative review of the observed and predicted impacts of climate change on shallow lakes in the Netherlands
and put these impacts in an international perspective. Most of these lakes are man-made and have preset water levels and poorly
developed littoral zones. Relevant climatic factors for these ecosystems are temperature, ice-cover and wind. Secondary factors
affected by climate include nutrient loading, residence time and water levels. We reviewed the relevant literature in order
to assess the impact of climate change on these lakes. We focussed on six management objectives as bioindicators for the functioning
of these ecosystems: target species, nuisance species, invading species, transparency, carrying capacity and biodiversity.
We conclude that climate change will likely (i) reduce the numbers of several target species of birds; (ii) favour and stabilize
cyanobacterial dominance in phytoplankton communities; (iii) cause more serious incidents of botulism among waterfowl and
enhance the spreading of mosquito borne diseases; (iv) benefit invaders originating from the Ponto-Caspian region; (v) stabilize
turbid, phytoplankton-dominated systems, thus counteracting restoration measures; (vi) destabilize macrophyte-dominated clear-water
lakes; (vii) increase the carrying capacity of primary producers, especially phytoplankton, thus mimicking eutrophication;
(viii) affect higher trophic levels as a result of enhanced primary production; (ix) have a negative impact on biodiversity
which is linked to the clear water state; (x) affect biodiversity by changing the disturbance regime. Water managers can counteract
these developments by reduction of nutrient loading, development of the littoral zone, compartmentalization of lakes and fisheries
management.
Groundwater-nitrate concentrations are compared between the experimental farm ‘De Marke’ — which was designed to minimize nutrient surpluses — and farms being representative for the sandy region of the Netherlands. Samples were collected during the period 1991–1999 at ‘De Marke’ and during 1992–1995 at 94 representative farms. Between 1991 and autumn 1992 groundwater nitrate at ‘De Marke’ decreased from 193 mg 1−1 to 115 mg 1−1. No decrease was found at the representative farms. The decrease at ‘De Marke’ was attributed to new farm management. After autumn 1992, groundwater nitrate at ‘De Marke’ fluctuated between 30 and 115 mg 1−1. A comparable pattern in time was found at other farms. This variation is attributed mostly to variation in groundwater table and precipitation. After autumn 1992, farm management did not result in a further reduction in groundwater nitrate. Only 9 of the 94 representative farms had an average nitrate concentration lower than that at ‘De Marke’ during 1992–1998. If differences in groundwater table and precipitation are taking into account, it is estimated that only three of the representative farms would have had a lower average nitrate concentration than ‘De Marke’.
Increasing population and consumption are placing unprecedented demands on agriculture and natural resources. Today, approximately a billion people are chronically malnourished while our agricultural systems are concurrently degrading land, water, biodiversity and climate on a global scale. To meet the world's future food security and sustainability needs, food production must grow substantially while, at the same time, agriculture's environmental footprint must shrink dramatically. Here we analyse solutions to this dilemma, showing that tremendous progress could be made by halting agricultural expansion, closing 'yield gaps' on underperforming lands, increasing cropping efficiency, shifting diets and reducing waste. Together, these strategies could double food production while greatly reducing the environmental impacts of agriculture.
Harmful (toxic, food web altering, hypoxia generating) cyanobacterial algal blooms (CyanoHABs) are proliferating world-wide due to anthropogenic nutrient enrichment, and they represent a serious threat to the use and sustainability of our freshwater resources. Traditionally, phosphorus (P) input reductions have been prescribed to control CyanoHABs, because P limitation is widespread and some CyanoHABs can fix atmospheric nitrogen (N(2)) to satisfy their nitrogen (N) requirements. However, eutrophying systems are increasingly plagued with non N(2) fixing CyanoHABs that are N and P co-limited or even N limited. In many of these systems N loads are increasing faster than P loads. Therefore N and P input constraints are likely needed for long-term CyanoHAB control in such systems. Climatic changes, specifically warming, increased vertical stratification, salinization, and intensification of storms and droughts play additional, interactive roles in modulating CyanoHAB frequency, intensity, geographic distribution and duration. In addition to having to consider reductions in N and P inputs, water quality managers are in dire need of effective tools to break the synergy between nutrient loading and hydrologic regimes made more favorable for CyanoHABs by climate change. The more promising of these tools make affected waters less hospitable for CyanoHABs by 1) altering the hydrology to enhance vertical mixing and/or flushing and 2) decreasing nutrient fluxes from organic rich sediments by physically removing the sediments or capping sediments with clay. Effective future CyanoHAB management approaches must incorporate both N and P loading dynamics within the context of altered thermal and hydrologic regimes associated with climate change.
It is now accepted that some human-induced climate change is unavoidable. Potential impacts on water supply have received much attention, but relatively little is known about the concomitant changes in water quality. Projected changes in air temperature and rainfall could affect river flows and, hence, the mobility and dilution of contaminants. Increased water temperatures will affect chemical reaction kinetics and, combined with deteriorations in quality, freshwater ecological status. With increased flows there will be changes in stream power and, hence, sediment loads with the potential to alter the morphology of rivers and the transfer of sediments to lakes, thereby impacting freshwater habitats in both lake and stream systems. This paper reviews such impacts through the lens of UK surface water quality. Widely accepted climate change scenarios suggest more frequent droughts in summer, as well as flash-flooding, leading to uncontrolled discharges from urban areas to receiving water courses and estuaries. Invasion by alien species is highly likely, as is migration of species within the UK adapting to changing temperatures and flow regimes. Lower flows, reduced velocities and, hence, higher water residence times in rivers and lakes will enhance the potential for toxic algal blooms and reduce dissolved oxygen levels. Upland streams could experience increased dissolved organic carbon and colour levels, requiring action at water treatment plants to prevent toxic by-products entering public water supplies. Storms that terminate drought periods will flush nutrients from urban and rural areas or generate acid pulses in acidified upland catchments. Policy responses to climate change, such as the growth of bio-fuels or emission controls, will further impact freshwater quality.
Agricultural pollutants in catchments are transported toward the discharging stream through various flow routes such as tube drain flow, groundwater flow, interflow, and overland flow. Direct measurements of flow route contributions are difficult and often impossible. We developed a field-scale setup that can measure the contribution of the tube drain flow route to the total discharge toward the surface water system. We then embedded these field-scale measurements in a nested measurement setup to asses the value of field-scale measurements for interpretation of catchment-scale discharge and nitrate concentrations using a linear flow route mixing model. In a lowland catchment, we physically separated the tube drain effluent from the discharge of all other flow routes. Upscaling the field-scale flow route discharge contributions to the subcatchment and the catchment scale with a linear flow route mixing model gave a good prediction of the catchment discharge. Catchment-scale nitrate concentrations were simulated well for a heavy rainfall event but poorly for a small rainfall event. The nested measurement setup revealed that the fluxes at a single field site cannot be representative for the entire catchment at all times. However, the distinctly different hydrograph reaction of the individual flow routes on rainfall events at the field site made it possible to interpret the catchment-scale hydrograph and nitrate concentrations. This study showed that physical separation of flow route contributions at the field scale is feasible and essential for understanding catchment-scale discharge generation and solute transport processes
The contributions of the participants to the MonNO3 workshop, organised by RIVM, GEUS and DMU in The Hague (Scheveningen), the Netherlands on 11-12 June 2003 are assembled in this report. More specifically, the report provides a synthesis of the papers and an outline of the workshop discussions on the methodology for monitoring the effectiveness of the EU Nitrates Directive Action Programmes. The legal requirements for this type of monitoring have been incorporated in Article 5(6) of the Nitrates Directive. Two different approaches -upscaling and interpolation- for describing the effect of Action Programmes on a national scale were defined but not discussed in detail, since this was beyond the scope of the MonNO3 workshop. All contributions presented make clear that water quality is not only influenced by agricultural practice but by other factors as well. Soil type, hydrological and geological characteristics of sediments or rocks (or of the surface water system), and climate and weather are examples of environmental factors that may cause differences in water quality, either between locations or in time. Dit rapport bevat de bijdragen van de deelnemers aan de MonNO3 workshop, georganiseerd door het RIVM, GEUS en DMU. De workshop is gehouden op 11 en 12 juni 2003 en vond plaats in Den Haag (Scheveningen). Het rapport geeft ook een synthese van deze bijdragen en de workshopdiscussies over de methoden om de effectiviteit van de EU Nitraatrichtlijn Actieprogramma's te monitoren. De wettelijke grondslag voor dit type monitor staan in de Nitraatrichtlijn, artikel 5(6).Er zijn twee verschillende benaderingswijzen om de effecten van de Actieprogramma's op nationale schaal te beschrijven, te weten opschalen en interpolatie. Deze benaderingswijzen zijn niet in detail bediscussieerd omdat dit buiten het terrein van de MonNO3 workshop lag. Uit alle bijdragen blijkt dat waterkwaliteit niet alleen wordt beinvloed door de landbouwpraktijk maar ook door andere factoren. Bodemtype, hydrogeologische karakteristieken van de bodem en de ondergrond, karakteristieken van het oppervlaktewatersysteem en karakteristieken van het klimaat en het weer zijn voorbeelden van "omgevingsfactoren" die de oorzaak kunnen zijn van in tijd en ruimte gemeten verschillen in waterkwaliteit.
The Dutch National Monitoring Programme for Effectiveness of the Minerals Policy (LMM) was initiated to allow detection of a statutory reduction in nitrate leaching caused by a decreasing N load. The starting point, or baseline, was taken as the nitrate concentration of the upper metre of groundwater sampled on 99 farms in the 1992-1995 period in the sandy areas of the Netherlands, where predominantly grass and maize grow. We found here that a reduction in nitrate leaching of more than 20% in future would almost certainly be detected with the LMM. Detecting downward trends due to decreasing N load will require nitrate concentrations to also be related to soil drainage, precipitation excess leading to groundwater recharge and to location. Furthermore, we found that about 16% of the N load in the Dutch sandy regions was being leached to the upper metre of groundwater in the 1992-1995 period. The critical N load in approximately 1990 for exceeding the EC limit value for nitrate, NO3, (50 mg L(-1)) in the upper metre of groundwater for the mean situation for grassland, maize and arable land in the sandy area was found to be 210 kg ha(-1) a(-1). Because manure management has been altered, the critical load found will be lower than the current critical load.
The warming trend of the last decades is now so strong that it is discernible in local temperature observations. This opens the possibility to compare the trend to the warming predicted by comprehensive climate models (GCMs), which up to now could not be verified directly to observations on a local scale, because the signal-to-noise ratio was too low. The observed temperature trend in western Europe over the last decades appears much stronger than simulated by state-of-the-art GCMs. The difference is very unlikely due to random fluctuations, either in fast weather processes or in decadal climate fluctuations. In winter and spring, changes in atmospheric circulation are important; in spring and summer changes in soil moisture and cloud cover. A misrepresentation of the North Atlantic Current affects trends along the coast. Many of these processes continue to affect trends in projections for the 21st century. This implies that climate predictions for western Europe probably underestimate the effects of anthropogenic climate change.
Nitrogen (N) and phosphorus (P) play a major role in the biogeochemical functioning of aquatic systems. N and P transfer to surface freshwaters has amplified during the 20th century, which has led to widespread eutrophication problems. The contribution of different sources, natural and anthropogenic, to total N and P loading to river networks has recently been estimated yearly using the Integrated Model to Assess the Global Environment - Global Nutrient Model (IMAGE-GNM). However, eutrophic events generally result from a combination of physicochemical conditions governed by hydrological dynamics and the availability of specific nutrient forms that vary at subyearly timescales. In the present study, we define for each simulated nutrient source: i) its speciation, and ii) its subannual temporal pattern. Thereby, we simulate the monthly loads of different N (ammonium, nitrate + nitrite, and organic N) and P forms (dissolved and particulate inorganic P, and organic P) to global river networks over the whole 20th century at a half-degree spatial resolution. Results indicate that, together with an increase in the delivery of all nutrient forms to global rivers, the proportion of inorganic forms in total N and P inputs has risen from 30 to 43% and from 56 to 65%, respectively. The high loads originating from fertilized agricultural lands and the increasing proportion of sewage inputs have led to a greater proportion of DIN forms (ammonium and nitrate), that are usually more bioavailable. Soil loss from agricultural lands, which delivers large amounts of particle-bound inorganic P to surface freshwaters, has become the dominant P source, which is likely to lead to an increased accumulation of legacy P in slow flowing areas (e.g., lakes and reservoirs). While the TN:TP ratio of the loads has remained quite stable, the DIN:DIP molar ratio, which is likely to affect algal development the most, has increased from 18 to 27 globally. Human activities have also affected the timing of nutrient delivery to surface freshwaters. Increasing wastewater emissions in growing urban areas induces constant local pressure on the quality of aquatic systems by delivering generally highly bioavailable nutrient forms, even in periods of low runoff.
This paper assesses historic changes in mean sea level around the coastline of the North Sea, one of the most
densely populated coasts in the world. Typically, such analyses have been conducted at a national level, and
detailed geographically wider analyses have not been undertaken for about 20 years. We analyse long re-
cords (up to 200 years) from 30 tide gauge sites, which are reasonably uniformly distributed along the coast-
line, and: (1) calculate relative sea level trends; (2) examine the inter-annual and decadal variations;
(3) estimate regional geocentric (sometimes also referred to as ‘absolute’) sea level rise throughout the
20th century; and (4) assess the evidence for regional acceleration of sea-level rise. Relative sea level changes
are broadly consistent with known vertical land movement patterns. The inter-annual and decadal variability
is partly coherent across the region, but with some differences between the Inner North Sea and the English
Channel. Data sets from various sources are used to provide estimates of the geocentric sea level changes. The
long-term geocentric mean sea level trend for the 1900 to 2011 period is estimated to be 1.5 ± 0.1 mm/yr for
the entire North Sea region. The trend is slightly higher for the Inner North Sea (i.e. 1.6 ± 0.1 mm/yr), and
smaller but not significantly different on the 95% confidence level for the English Channel (i.e. 1.2 ±
0.1 mm/yr). The uncertainties in the estimates of vertical land movement rates are still large, and the results
from a broad range of approaches for determining these rates are not consistent. Periods of sea level rise ac-
celeration are detected at different times throughout the last 200 years and are to some extent related to air
pressure variations. The recent rates of sea level rise (i.e. over the last two to three decades) are high com-
pared to the long-term average, but are comparable to those which have been observed at other times in
the late 19th and 20th century.
Introduction. In the late 1980s Atsumu Ohmura and several
others (e.g. Ohmura and Lang, 1989)
discovered that the amount of solar radiation
reaching the surface had decreased at
many radiation measurement sites between
1960 and 1990. Near densely-populated
areas and industries, 30% less solar radiation
was reaching the ground in the 1980s than
a few decades earlier (Wild, 2009). However,
since the mid 1980s a significant increase in
visibility has been noted in western Europe
(e.g. Doyle and Dorling, 2002), and there are
strong indications that a reduction in aerosol
load from anthropogenic emissions (in
other words, air pollution) has been the
dominant contributor to this effect, which
is also referred to as ‘brightening’. In the
Netherlands visibility, sunshine duration,
surface global short-wave radiation and
temperature have shown a significant rise
during this period, consistent with direct
and indirect aerosol effects, implying large
regional aerosol effects on climate. The brightening has been stronger during continental
windflow than during maritime episodes.
This article discusses the evidence for
brightening in the Netherlands and its possible
connection to the accelerated warming
since 1985.
We applied wave theory to calculate the extent and frequency that we would expect wave-driven surface water movements to disturb the sediments in 36 Florida lakes covering a broad range of surface areas and mean depths. The calculated per cent of the lakebed subject to wave disturbance at one time or another ranged from 6 to 100% and the per cent of the time 50% of the lakebed was disturbed ranged from 0 to 65%. The large Florida lakes, Apopka, Okeechobee, and Istokpoga showed high levels of calculated wave disturbance, which was consistent with the conclusions of previous investigations. Historic water level fluctuations in Lake Apopka were calculated to have major effects on wave disturbance in that lake. The dynamic ratio (the square root of lake surface area in square kilometers divided by the mean depth in meters) was significantly related to various measures of wave disturbance in our sample lakes. For lakes with ratio values above about 0.8 the entire lakebed was subject to wave disturbance at least some of the time. The dynamic ratio was also related to lake water quality. We found that increases in the dynamic ratio were significantly related to decreases in water quality as measured by total phosphorus, total nitrogen, chlorophyll, and Secchi disk depth. Calculations of wind disturbance by waves need to be modified in lakes with extensive beds of macrophytes, where water levels change and in periods where climatic fluctuations result in changes in wind regimes.
A major threat to freshwater taxon diversity is the alteration of natural catchment Land use into agriculture, industry or urban areas and the associated eutrophication of the water. In order to stop freshwater biodiversity loss, it is essential to quantify the relationships between freshwater diversity and catchment Land use and water nutrient concentrations.
A literature survey was carried out on biodiversity data from rivers and streams. Fish and macroinvertebrates were selected as focal groups as they are widely used as indicator species of river and stream health. Only published data were selected that (a) compared data found at impaired sites with a pristine reference situation (either in time or space), (b) clearly defined the stressors studied (Land use cover and/or nutrient concentrations), and (c) clearly defined biodiversity (number of native species, species lists or IBI‐scores).
The number of native taxa found in each study was transferred in an index of relative taxon richness (RTR) ranging from 0 (severely altered) to 100 (pristine reference conditions). Only those taxa were included that were (at least) present in the most pristine situation. This made it possible to combine, compare and analyse results from different studies. Catchment Land use was expressed as the percentage of non‐natural Land use (agriculture, industry, housing or mining). As a measure of nutrients, the concentrations of NO 3 , NH 4 , PO 4 , total N and total P in the river and stream water were used.
Over 240 published articles have been studied, but only 22 met the criteria described above and could be used for further analysis.
This study showed that altered catchment Land use has a major effect on freshwater biodiversity and that the rate of species loss is serious; on average every 10% of lost natural catchment Land use cover leads to a loss of almost 6% (±0.83) of the native freshwater fish and macroinvertebrate species.
Copyright © 2008 John Wiley & Sons, Ltd.
The past few decades have seen a massive increase in coastal eutrophication globally, leading to widespread hypoxia and anoxia, habitat degradation, alteration of food-web structure, loss of biodiversity, and increased frequency, spatial extent, and duration of harmful algal blooms. Much of this eutrophication is due to increased inputs of nitrogen to coastal oceans. Before the advent of the industrial revolution and the green revolution, the rate of supply of nitrogen on Earth was limited to the rate of bacterial nitrogen fixation, but human activity now has roughly doubled the rate of creation of reactive, biologically available nitrogen on the land masses of the Earth. Regional variation in this increase is great, and some regions of the Earth have seen little change, while in other areas, nitrogen fluxes through the atmosphere and through rivers have increased by 10-15-fold or more. Much of this increase has occurred over the past few decades. Increased use of synthetic nitrogen fertilizer and increased intensity of meat production has led the change globally and in many regions, and agricultural sources are the largest source of nitrogen pollution to many of the planet's coastal marine ecosystems. The rate of change in nitrogen use in agriculture is incredible, and over half of the synthetic nitrogen fertilizer ever produced has been used in the past 15 years. Atmospheric deposition of nitrogen from fossil fuel combustion also contributes to the global budget for reactive nitrogen and is the largest single source of nitrogen pollution in some regions. Technical solutions for reducing nitrogen pollution exist at reasonable cost, but implementation has been poor in many regions.
The fate and cycling of macronutrients introduced into estuaries depend upon a range of interlinked processes. Hydrodynamics and morphology in combination with freshwater inflow control the freshwater flushing time, and the timescale for biogeochemical processes to operate that include microbial activity, particle-dissolved phase interactions, and benthic exchanges. In some systems atmospheric inputs and exchanges with coastal waters can also be important. Climate change will affect nutrient inputs and behaviour through modifications to temperature, wind patterns, the hydrological cycle, and sea level rise. Resulting impacts include: 1) inundation of freshwater systems 2) changes in stratification, flushing times and phytoplankton productivity 3) increased coastal storm activity 4) changes in species and ecosystem function. A combination of continuing high inputs of nutrients through human activity and climate change is anticipated to lead to enhanced eutrophication in the future. The most obvious impacts of increasing global temperature will be in sub-arctic systems where permafrost zones will be reduced in combination with enhanced inputs from glacial systems. Improved process understanding in several key areas including cycling of organic N and P, benthic exchanges, resuspension, impact of bio-irrigation, particle interactions, submarine groundwater discharges, and rates and magnitude of bacterially-driven recycling processes, is needed. Development of high frequency in situ nutrient analysis systems will provide data to improve predictive models that need to incorporate a wider variety of key factors, although the complexity of estuarine systems makes such modelling a challenge. However, overall a more holistic approach is needed to effectively understand, predict and manage the impact of macronutrients on estuaries.
For the evaluation of policy action programs to improve groundwater quality, research institutes and governments intensively monitor nitrate concentrations in shallow or near surface groundwater. However, trend detection is often hampered by the large seasonal and multi-annual temporal variability in nitrate concentrations, especially in shallow groundwater within 0–5 m below the surface in relatively humid regions. This variability is mainly caused by variations in precipitation excess (precipitation minus evapotranspiration) that results in strong variability in groundwater recharge. The objective of this study was to understand and quantify this weather-induced variability in shallow groundwater nitrate concentrations.
We present an example of measured weather related variations in shallow groundwater nitrate concentrations from De Marke, an intensively monitored experimental farm in The Netherlands. For the quantification of the weather-induced variability, concentration-indices were calculated using a 1D model for water and solute transport. The results indicate that nitrate concentrations in the upper meter of groundwater at De Marke vary between 55% and 153% of the average concentration due to meteorological variability. The concentration-index quantification method was successfully used to distinguish weather related variability from human-induced trends in the nitrate concentration monitoring data from De Marke. Our model simulations also shows that sampling from fixed monitoring wells produces less short term variability than measuring from open boreholes. In addition, using larger screen depths and longer screens filters out short term temporal variability at the cost of a more delayed detection of trends in groundwater quality.
For the evaluation of action programs to reduce surface water pollution, water authorities invest heavily in water quality monitoring. However, sampling frequencies are generally insufficient to capture the dynamical behavior of solute concentrations. For this study, we used on-site equipment that performed semicontinuous (15 min interval) NO(3) and P concentration measurements from June 2007 to July 2008. We recorded the concentration responses to rainfall events with a wide range in antecedent conditions and rainfall durations and intensities. Through sequential linear multiple regression analysis, we successfully related the NO(3) and P event responses to high-frequency records of precipitation, discharge, and groundwater levels. We applied the regression models to reconstruct concentration patterns between low-frequency water quality measurements. This new approach significantly improved load estimates from a 20% to a 1% bias for NO(3) and from a 63% to a 5% bias for P. These results demonstrate the value of commonly available precipitation, discharge, and groundwater level data for the interpretation of water quality measurements. Improving load estimates from low-frequency concentration data just requires a period of high-frequency concentration measurements and a conceptual, statistical, or physical model for relating the rainfall event response of solute concentrations to quantitative hydrological changes.
In the sandy regions of The Netherlands, high losses of N from intensified dairy farms are threatening the environment. Therefore, government defined decreasing maximum levy-free N surplusses for the period 1998–2008. On most dairy farms, the current N surplus has to be reduced by half at least. Farmers fear that realizing these surplusses will be expensive, because it limits application of animal manure, which then has to be exported or additional land has to be bought. Moreover, farmers are worried about the impact on soil fertility. To explore the possibilities for reducing surplusses of average intensive farms by improved nutrient management, farming systems research is carried out at prototype farm De Marke. Results are compared with results of a commercial farm in the mid-1980s, the moment that systems research started and introduction of the milk quota system put a halt to further intensification. Results indicate that average intensive farms can realise a reduction in N surplus to a level below the defined final maximum, without the need to buy land or to export slurry. Inputs of N in purchased feeds and fertilisers decreased by 56 and 78%, respectively. Important factors are reduced feed intake per unit milk, as a result of a higher milk yield per cow, less young stock and judicious feeding, an improved utilization of home-made manure and a considered balance between the grassland and maize area. Changed soil fertility status did not constrain crop production. Nitrate concentration in the upper groundwater decreased from 200 to 50 mg l-1, within a few years.
Traditionally, monitoring of soil, groundwater and surface water quality is coordinated by different authorities in the Netherlands. Nowadays, the European Water Framework Directive (EU, 2,000) stimulates an integrated approach of the complete soil-groundwater-surface water system. Based on water quality data from several test catchments, we propose a conceptual model stating that stream water quality at different discharges is the result of different mixing ratios of groundwater from different depths. This concept is used for a regional study of the groundwater contribution to surface water contamination in the Dutch province of Noord-Brabant, using the large amount of available data from the regional monitoring networks. The results show that groundwater is a dominant source of surface water contamination. The poor chemical condition of upper and shallow groundwater leads to exceedance of the quality standards in receiving surface waters, especially during quick flow periods.
Sediment Transport, Light and Algal Growth in the Markermeer: A Two-Dimensional Water Quality Model for a Shallow Lake
- E H S Van Duin
Van Duin, E.H.S., 1992. Sediment Transport, Light and Algal Growth in the Markermeer: A
Two-Dimensional Water Quality Model for a Shallow Lake. PhD-Thesis Wageningen
University, The Netherlands.
De Nederlandse landbouwexport 2017
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statistiek & Wageningen University and Research. The Hague, the Netherlands.
Effect of Biota on Fine Sediment Transport Processes. Dissertation Technical University of Delft
- M A De Lucas Pardo
De Lucas Pardo, M.A., 2014. Effect of Biota on Fine Sediment Transport Processes. Dissertation Technical University of Delft, The Netherlands, A study of Lake Markermeer.
Monitoring effectiveness of the EU Nitrates Directive Action Programmes. Results of the international MonNO3 workshop in the Netherlands
- B Fraters
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- W J Willems
- J Stockmarr
- R Grant
Fraters, B., Kovar, K., Willems, W.J., Stockmarr, J., Grant, R., 2005. Monitoring effectiveness
of the EU Nitrates Directive Action Programmes. Results of the international MonNO3
workshop in the Netherlands, 11-12 June 2003. RIVM Report 500003007/2005
(Bilthoven. the Netherlands).
- B Freedman
Freedman, B. (Ed.), 2014. Global environmental change. Springer, Dordrecht, the Netherlands.
KNMI Climate Scenarios 2006 for the Netherlands
- Knmi
KNMI, 2006. KNMI Climate Scenarios 2006 for the Netherlands, KNMI Scientific Report
WR 2006-01, De Bilt, the Netherlands, 34 pp.
KNMI’14 Climate Scenarios for the Netherlands; a Guide for Professionals in Climate Adaptation
- Knmi
KNMI, 2015. KNMI'14 Climate Scenarios for the Netherlands; a Guide for Professionals in
Climate Adaptation, KNMI, De Bilt, the Netherlands, 34 pp.
KPP-Lange termijn Zoetwatervoorziening
- N Kramer
Kramer, N. 2018 (in Dutch). KPP-Lange termijn Zoetwatervoorziening. Analyse 100 jaar
reeks. Deltares report 11200590-000-BGS-0005, Utrecht, the Netherlands.
- M H Van Der Weijden
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Van der Weijden, M.H., Roos, M., 2015 (in Dutch). MWTL Meetplan 2016; Monitoring
Waterstaatkundige Toestand des Lands;
Mud Dynamics in the Markermeer
- T Vijverberg
Vijverberg, T., 2008. Mud Dynamics in the Markermeer. MSc-Thesis Delft University of
Technology, Delft, The Netherlands.
Western Europe is warming much faster than expected
- Van Oldenborgh
Monitoring Waterstaatkundige Toestand des Lands
- M H Van Der Weijden
- M Roos