Jeroen De Klein

Wageningen University & Research | WUR · Department of Aquatic Ecology and Water Quality Management

Controlling non-point source pollution is often difficult and costly. Therefore, focusing on areas that contribute the most, so-called critical source areas (CSAs), can have economic and ecological benefits. CSAs are often determined using a modelling approach, yet it has proved difficult to calibrate the models in regions with limited data availab...

p>Nutrients are essential resources for food production but are used inefficiently, and thereby they pollute inland and coastal waters and are lost into the oceans. Nutrient conservation by retention and consecutive reuse would prevent nutrient losses to the atmosphere and downstream ecosystems. We present Smart Nutrient Retention Networks (SNRNs)...

Abstract Faecal indicator bacteria (FIB) are used for the assessment of faecal pollution and possible water quality deterioration. There is growing evidence that FIB used in temperate regions are not adequate and reliable to detect faecal pollution in tropical regions. Hence, this study evaluated the adequacy of FIB, including total coliforms (TC),...

Faecal indicator bacteria (FIB) are used for the assessment of faecal pollution and possible water quality deterioration. There is growing evidence that FIB used in temperate regions are not adequate and reliable to detect faecal pollution in tropical regions. Hence, this study evaluated the adequacy of FIB, including total coliforms (TC), Escheric...

• Shallow lakes can shift between stable states as a result of anthropogenic or natural drivers. Four common stable states differ in dominant groups of primary producers: submerged, floating, or emergent macrophytes or phytoplankton. Shifts in primary producer dominance affect key supporting, provisioning, regulating, and cultural ecosystem service...

Rivers are exporting increasing amounts of nitrogen (N) to lakes, which is leading to eutrophication. However, the seasonality apparent in nutrient loading, especially in tropical areas, is thus far only partially understood. This study aims to better understand the seasonality and the sources of dissolved inorganic nitrogen (DIN) inputs from sub-b...

Lake Dianchi suffered from severe eutrophication for decades. Past efforts to reduce the eutrophication were not very effective. The objective of this study is to improve our understanding of nitrogen (N) and phosphorus (P) loadings and to analyze to what extent they exceed critical nutrient loadings of Lake Dianchi. To this end, we applied the nut...

Wetlands play an important role in the provision of important ecosystem services like the provision of clean water to the world, adaptation to climate change, and support for biodiversity; although they are sometimes also associated with adverse climate effects. Wetlands are, however, currently grossly underrepresented in global environmental model...

A long‐standing debate in ecology deals with the role of nitrogen and phosphorus in management and restoration of aquatic ecosystems. It has been argued that nutrient reduction strategies to combat blooms of phytoplankton or floating plants should solely focus on phosphorus (P). The underlying argument is that reducing nitrogen (N) inputs is ineffe...

Drainage ditches are ubiquitous yet understudied features of the agricultural landscape. Nitrogen pollution disrupts the nutrient balance of drainage ditch ecosystems, as well as the waterbodies in which they drain. Denitrification can help ameliorate the impact of N-fertilization by converting reactive nitrogen into dinitrogen gas. However, factor...

Vegetated ditches and wetlands are important sites for nutrient removal in agricultural catchments. About half of the influx of inorganic nitrogen can be removed from these ecosystems by denitrification. Previous studies have shown that denitrification in aquatic ecosystems is strongly temperature dependent, resulting from temperature-dependent oxy...

All over the world freshwater ecosystems like ponds, ditches and lakes suffer from nutrient-driven regime shifts from submerged plants to dominance by algae or free-floating plants. Although freshwaters are often connected and part of a network, most of our current knowledge on regime shifts comes from studies of isolated ecosystems. The few studie...

Water is at the forefront of the economic agenda of Ethiopian government and Tana basin has been identified as a major economic corridor because of the basin’s immense water resource potential for socioeconomic development. For effective and sustainable utilization of water resources in the basin, it is essential to assess the water quality in spat...

Submerged macrophytes play an important role in maintaining good water quality in shallow lakes. Yet extensive stands easily interfere with various services provided by these lakes, and harvesting is increasingly applied as a management measure. Because shallow lakes may possess alternative stable states over a wide range of environmental condition...

Ecosystem models aiming to describe higher level variables such as total phosphorus and water transparency will always remain a crude simplification of reality regardless of the detail that is included. This weak link between model and reality implies that it will be impossible to accurately parameterize each of the model components on basis of emp...

Worldwide the area of free-floating plants is increasing, which can be expected to alter methane (CH4) emissions from aquatic systems in several ways. A large proportion of the CH4 produced may become oxidized below the plants due to the accumulation of CH4 as a result of a decrease in the diffusive water-atmosphere flux and the entrapment of part...

Recent studies from temperate lakes indicate that eutrophic systems tend to emit less carbon dioxide (CO2) and bury more organic carbon (OC) than oligotrophic ones, rendering them CO2 sinks in some cases. However, the scarcity of data from tropical systems is critical for a complete understanding of the interplay between eutrophication and aquatic...

It is generally acknowledged that fate models for engineered nanoparticles (ENPs) hardly can be validated, given present limitations in analytical methods available for ENPs. Here we report on progress towards validation of the spatially resolved hydrological ENP fate model NanoDUFLOW, by comparing measured and modeled concentrations of < 450 nm Ce...

Annual sulfate mass balances have been constructed for four low-lying peat polders in the Netherlands, to resolve the origin of high sulfate concentrations in surface water, which is considered a water quality problem, as indicated amongst others by the absence of sensitive water plant species. Potential limitation of these plants to areas with low...

Site specific exposure assessments for engineered nanoparticles (ENPs) require spatially explicit fate models, which however are not yet available. Here we present an ENP fate model (NanoDUFLOW) that links ENP specific process descriptions to a spatially explicit hydrological model. The link enables the realistic modelling of feedbacks between loca...

Dominance of free-floating plants poses a threat to biodiversity in many freshwater ecosystems. Here we propose a theoretical framework to understand this dominance, by modeling the competition for light and nutrients in a layered community of floating and submerged plants. The model shows that at high supply of light and nutrients, floating plants...

Water quality modelling deals with multidisciplinary questions ranging from fundamental to applied. Addressing this broad range of questions requires multiple analysis techniques and therefore multiple frameworks. Through the recently developed database approach to modelling (DATM), it has become possible to run a model in multiple software framewo...

This project aims at finding cost-efficient adaptive measures to meet the EU Water Framework Directive goals for the Dommel River (The Netherlands). Both acute and long-term impacts of the urban wastewater system (treatment plant and sewers) on the chemical and ecological quality of the river are studied. An integrated model, which proved to be a p...

Nederland is rijk aan sloten. Samen zijn ze maar liefst 300.000 kilometer lang. De sloten zijn onmisbaar voor de aan- en afvoer van water en vormen een geliefd onderdeel van ons karakteristieke polderlandschap. Allerlei natuurlijke processen spelen zich af in deze door de mens aangelegde wateren en ze herbergen ook nog eens tal van interessante pla...

This project aims at finding cost-efficient measures to meet the Water Framework Directive goals for the Dommel River (The Netherlands). Both acute and long-term impacts of the urban wastewater system (wastewater treatment plant and sewers) on the chemical and ecological quality of the river are studied. An integrated model, which proved to be a po...

Simulation modelling in ecology is a field that is becoming increasingly compartmentalized. Here we propose a Database Approach To Modelling (DATM) to create unity in dynamical ecosystem modelling with differential equations. In this approach the storage of ecological knowledge is independent of the language and platform in which the model will be...

The KALLISTO project aims at finding cost-efficient sets of measures to meet the Water Framework Directive (WFD) derived goals for the river Dommel. Within the project, both acute and long term impacts of the urban wastewater system on the chemical and ecological quality of the river are studied with an integral monitoring campaign in the urban was...

This project aims at finding cost-efficient sets of measures to meet the Water Framework Directive (WFD) derived goals for the Dommel River (The Netherlands). Within the project, both acute and long-term impacts of the urban wastewater system on the chemical and ecological quality of the river are studied with a monitoring campaign in the urban was...

Stream restoration often aims at mitigating nutrient pollution in aquatic ecosystems. However, despite recent research efforts, effects of restoration practices on in-stream nitrogen removal remain unclear. In this study, denitrification rates as well as factors controlling denitrification in unrestored and restored sections of two Danish streams (...

Modeling of integrated urban water systems (IUWS) has seen a rapid development in recent years. Models and software are available that describe the process dynamics in sewers, wastewater treatment plants (WWTPs), receiving water systems as well as at the interfaces between the submodels. Successful applications of integrated modeling are, however,...

In many countries wetlands are constructed or restored for removing nutrients from surface water. At the same time vegetated wetlands can act as carbon sinks when CO2 is sequestered in biomass. However, it is well known that wetlands also produce substantial amounts of greenhouse gasses CH4 and N2O. Especially N2O, resulting from nitrification and...

De sulfaatbalansen van perceel, sloot en polder zijn nauw met elkaar verweven. Er bestaat onduidelijkheid over de effecten van sulfaat op de waterkwaliteit en over het relatieve belang van verschillende bronnen van sulfaat in het Hollands-Utrechtse veenlandschap. Deze studie laat zien dat oxidatie van het gebiedseigen veen meestal de belangrijkste...

Annual sulfate mass balances have been constructed for low-lying peat polders in the Netherlands. These peat polders are generally used for dairy farming or nature conservation, and can have large areas of shallow ditches and ponds (mean 16%, range 6-43%). As a consequence of continuous drainage, the peat (organic matter and sulfides) in these pold...

Background/Question/Methods Agricultural drainage ditches are often polluted with nitrogen, which contributes to eutrophication of the lakes, rivers and reservoirs in which they drain. Denitrification permanently removes nitrogen from these systems. However, despite a considerable research effort, factors affecting denitrification are still poorl...

Sulfaatconcentraties in het oppervlaktewater van het West-Nederlandse laagveengebied kunnen bijzonder hoog zijn. Er bestaat onduidelijkheid over de bronnen en de effecten van dit sulfaat. De huidige studie combineert jaarbalansen op perceel-, polder- en stroomgebiedsschaal met een analyse van de ruimtelijke variatie in sulfaatconcentraties, en met...

The KALLISTO project aims at finding cost-efficient sets of measures to meet the Water Framework Directive (WFD) derived goals for the Dommel River (The Netherlands). An integrated model, which showed to be a powerful tool to analyze the interactions within the integrated urban wastewater system, was first used to evaluate measures in the urban was...

The wastewater system of Eindhoven has been equipped with RTC control stations in the interceptor sewer since the early 1970s. The original volume-based RTC strategy aimed at maximizing the use of the in-sewer storage capacity and of the hydraulic capacity of the downstream WWTP. The water authorities now face receiving water problems related to in...

To set accurate critical values for the protection of lakes and coastal areas, it is crucial to know the seasonal variation of nutrient exports from rivers. This article presents an improved method for estimating export and in-stream nutrient retention and its seasonal variation. For 13 lowland river catchments in Western Europe, inputs to surface...

In a microcosm 15N enrichment experiment we tested the effect of floating vegetation (Lemna sp.) and submerged vegetation (Elodea nuttallii) on denitrification rates, and compared it to systems without macrophytes. Oxygen concentration, and thus photosynthesis, plays an important role in regulating denitrification rates and therefore the experiment...

Global warming and the alteration of the global nitrogen cycle are major anthropogenic threats to the environment. Denitrification, the biological conversion of nitrate to gaseous nitrogen, removes a substantial fraction of the nitrogen from aquatic ecosystems, and can therefore help to reduce eutrophication effects. However, potential responses of...

Nitrogen compounds are transformed by a complicated network of competing geochemical processes or microbial pathways, each performed by a different ecological guild of microorganisms. Complete experimental unravelling of this network requires a prohibitive experimental effort. Here we present a simple model that predicts relative rates of hypotheti...

Nature of the problem • Freshwater ecosystems play a key role in the European nitrogen (N) cycle, both as a reactive agent that transfers, stores and processes N loadings from the atmosphere and terrestrial ecosystems, and as a natural environment severely impacted by the increase of these loadings. Approaches • This chapter is a review of major p...

Nature of the problem • Freshwater ecosystems play a key role in the European nitrogen (N) cycle, both as a reactive agent that transfers, stores and processes N loadings from the atmosphere and terrestrial ecosystems, and as a natural environment severely impacted by the increase of these loadings. Approaches • This chapter is a review of major pr...

Deze meetcampagne geeft meer inzicht in het vermogen van een waterloop om nutriënten vast te leggen of na te leveren (retentie). Dit inzicht draagt bij aan het beter inschatten en optimaliseren van waterkwaliteitsmaatregelen. Hiertoe zijn een genormaliseerd en een meanderend traject in het Zeegserloopje hoogfrequent bemeten in drie perioden van elk...

Voor de evaluatie van maatregelen die worden genomen om de ambities van de Kaderrichtlijn Water te realiseren, is een goed begrip van de retentie van stikstof en fosfor in het oppervlaktewater cruciaal. In dit rapport wordt een ‘State of the art’ beeld gegeven van de manier waarop deze retentie wordt geschat op verschillende schalen. Er worden een...

Beken en rivieren transporteren nutriënten (vooral stikstof en fosfor), afkomstig van puntbronnen en diffuse lozingen, naar benedenstrooms gelegen meren en kustwateren. Dit leidt tot eutrofieringsverschijnselen in veel gebieden. Maar niet alle nutriënten die worden geloosd bereiken uiteindelijk de benedenstroomse wateren. Tijdens het transport vind...

Onderzocht is in hoeverre de implementatie van de KRW via het mestbeleid en via het regionale KRW-maatregelenpakket bijdraagt aan de realisatie van de beoogde concentraties nutriënten in het oppervlaktewater. Daarnaast is verkend of aanvullende maatregelen tot een bijdrage aan de realisatie van deze normen kunnen bijdragen. Daartoe zijn de milieuef...

In deze studie is een analyse gemaakt van de herkomst van nutriënten die via de grote rivieren op het Nederlandse deel van de Noordzee worden geloosd. Via de flow-path methode is berekend welk deel afkomstig was uit het buitenland en welk deel van binnenlandse bronnen. Voorts is berekend wat de bijdrage is van 19 deelstroomgebieden in Nederland aan...

In deze studie is een analyse gemaakt van het effect van hydromorfologische ingrepen op nutriënten concentraties in het oppervlaktewater. Het betrof een nadere kwantificering van effecten van inpoldering, grondwaterstandverlaging en normalisatie van beken. In twee voorbeeldgebieden (stagnant en stromend water) is de methodiek gedemonstreerd en is a...

Deze studie geeft inzicht in de effecten van hydromorfologische ingrepen op fysisch-chemische grootheden in het oppervlaktewater en kan gebruikt worden voor afleiding MEP/GEP en de onderbouwing hiervoor. Het koppelen van ecologische effecten aan hydromorfologische ingrepen die via de fysisch-chemische toestand (nutriënten en overige grootheden) lop...

De leerstoelgroep Aquatische Ecologie en Waterkwaliteitsbeheer van Wageningen Universiteit gaat de komende vier jaar vernieuwend onderzoek uitvoeren in sloten. Het onderzoek wordt gefinancierd door STOWA en de direct betrokken waterbeheerders. Enerzijds zal het onderzoek zich richten op het verkrijgen van meer inzicht in de fundamentele processen a...

Phosphorus (P) losses caused by intensive agriculture are known to have potentially large negative effects on the water quality of lakes. However, due to the buffering capacity of soils and lake ecosystems, such effects may appear long after intensive agriculture started. Here we present the study of a coupled shallow lake catchment model, which al...

We developed a dynamic model to investigate the effect of atmospheric carbon dioxide (CO2) increase on plant growth in freshwater ecosystems. Steady-state simulations were performed to analyze the response of phytoplankton and submerged macrophytes to atmospheric CO2 elevation from 350 to 700 ppm. We studied various conditions that may affect this...

In this study results are presented of investigations on the development of a cucumber crop in a closed rockwool system and on the potential change in microbial suppressiveness due to different disinfection methods after inoculating part of the plants with the fungal pathogen Pythium aphanidermatum. Two trials were executed at which the core treatm...

The potential for above-ground and below-ground uptake and subsequent internal translocation of ammonium (NH4+) and nitrate (NO3−) by the macroalga Chara spp. was investigated. In a two compartment experimental set-up separating above-ground and below-ground algal parts, the charophytes were exposed to various combinations of 15N-labelled NH4+ and...

This study focuses on the uncertainties in the fate of nitrogen (N) in the Netherlands. Nitrogen inputs into the Netherlands in products, by rivers, and by atmospheric deposition, and microbial and industrial fixation of atmospheric N2 amount to about 4450 Gg N y–1. About 60% of this N is transported out of the Netherlands in products. The fate of...

Enhanced levels of nitrogen in the environment may have several adverse effects, including decreased plant species diversity in (semi) natural terrestrial ecosystems, eutrophication of surface waters, pollution of groundwater due to nitrate leaching and global warming due to nitrous and nitrogen oxide (N2O and NOx) emissions. To determine the effec...

Stedenbouwkundigen hebben het water ontdekt als sierend en recreatief element in nieuwe woonwijken. Toch hoor je ook steeds vaker negatieve berichten over al dat nieuwe oppervlaktewater. Deze brochure gaat in op de vraag of deze veronderstellingen reëel zijn. Er komen verschillende plagen en ziekten aan bod, die in verband worden gebracht met de aa...

Many surface waters in The Netherlands are polluted with nutrients from agricultural land. Riparian buffer zones have been shown to be very valuable in reducing non-point source pollution from agricultural land to streams. The nitrogen removal in two riparian zones vegetated with alder thicket and grass respectively and the contribution of denitrif...

In the abatement of eutrophication of standing waters management of sources and transport of nutrients in river catchments is crucial. However the transport of nitrogen and phosphorus can vary significantly among (sub) catchments as a result of different physical, chemical and biotic factors. Qualitative and quantitative differences in nutrient pat...