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National scale assessment of total trihalomethanes in Irish drinking water

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Abstract

Ireland reported the highest non-compliance with respect to total trihalomethanes (TTHMs) in drinking water across the 27 European Union Member States for the year 2010. We carried out a GIS-based investigation of the links between geographical parameters and catchment land-uses with TTHMs concentrations in Irish drinking water. A high risk catchment map was created using peat presence, rainfall (>1400 mm) and slope (<5%) and overlain with a map comprising the national dataset of routinely monitored TTHM concentrations. It appeared evident from the map that the presence of peat, rainfall and slope could be used to identify catchments at high risk to TTHM exceedances. Furthermore, statistical analyses highlighted that the presence of peat soil with agricultural land was a significant driver of TTHM exceedances for all treatment types. PARAFAC analysis from three case studies identified a fluorophore indicative of reprocessed humic natural organic matter as the dominant component following treatment at the three sites. Case studies also indicated that (1) chloroform contributed to the majority of the TTHMs in the drinking water supplies and (2) the supply networks contributed to about 30 mg L À1 of TTHMs.

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... Measurements of DBP levels in drinking water have been carried out regularly worldwide (Furst et al. 2019;O'Driscoll et al. 2018;Yao et al. 2019). In Iran, a number of studies (Ahmadi and Ramavandi 2014;Alipour and Ghanbarnejad 2014;Babaei et al. 2015;Ghoochani et al. 2016;Kalankesh et al. 2019;Mohammadi et al. 2019;Mohammadi et al. 2016;Nadali et al. 2019;Ramavandi and Asgari 2012) have investigated THM formation potential, THM concentrations in tap drinking water, and its related health risks in different parts of the country. ...
... Amjad et al. (2013) in Pakistan also found that > 85% of THMs were CF. O'Driscoll et al. (2018) in Ireland, Chang et al. (2010) in Taiwan, and Ahmed et al. (2019) in Bangladesh also found that the majority of THMs in drinking water were CF. ...
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Trihalomethanes (THMs) are one of the most common classes of disinfection by-products. In this study, the temporospatial trends and health risks due to exposure to THMs in the Tabriz water distribution network were investigated. THM series were analyzed using gas chromatography equipped with electron capture detector. The non-carcinogenic and carcinogenic risks due to exposure to THMs were calculated using Monte Carlo simulations. Mean concentrations of THMs in winter and spring were 10.2 ± 9.3 μg/l and 252 ± 185.9 μg/l, respectively. More than 80% of THMs identified were bromodichloromethane. The mean values of lifetime cancer risk (LTCR) of THMs were calculated as 4.23E−06 and 2.38E−04 for winter and spring, respectively. This study showed that there were noticeable levels of THMs in Tabriz water distribution network, especially in the center of the city. Although the non-cancer risk through THMs was below permissible recommended levels, the cancer risk likely remains due to high levels of THMs in some locations.
... The high non-compliance has been attributed to high percentage cover of organic soils, a heavy reliance on surface water (~75%) coupled with a historical lack of understanding of NOM and treatability (O'Driscoll et al. 2018). In Ireland, half of the land area of the country is considered to be underlain by limestone, and the majority of this is considered karstified to some degree (Naughton et al. 2012). ...
... As previously shown in Irish supplies, chloroform was the most prominent THM (O'Driscoll et al. 2018). C2, the terrestrial-delivered reprocessed organic matter, was responsible for majority of THM production in the distribution network. ...
Article
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Groundwater offers an important source for drinking water around the world; however, groundwater quality is under increasing pressure and is particularly vulnerable in karst areas. Total organic carbon (TOC) is significantly related to groundwater quality and when not removed by water treatment processes can give rise to the formation of disinfection by-products trihalomethanes (THMs) above the level of compliance. This study investigated the source of organic matter giving rise to the THM exceedances in a groundwater supply in a karst area. Results highlighted that source water for this groundwater supply was prone to surface water infiltration linked to rainfall events; was not accurately captured in the zone of contribution (ZoC); had inadequate treatment of natural organic matter (NOM) and suffered THM exceedances in 45% of sampling events. THMs were mostly represented by chloroform and caused by terrestrial delivered reprocessed organic matter. This work will support water managers tasked with decision-making.
... Chlorine agents are used in raw water to significantly reduce the charge of pollutants in the pre-chlorination (oxidation) process [3,4]. However, the reaction of chlorine with NOM or micro-contaminants during this process leads to the formation of carcinogenic trihalomethanes (THMs) and haloacetic acids (HAAs) [5][6][7][8]. In the coagulation, flocculation and precipitation units, the turbidity of the water is removed and then the final residues are removed by filtration. ...
... Elimination or reduction of pollution and damages is a major problem. The removal of organic matter by coagulation depends on the amount, nature and structure of the organic matter in the water environment, the coagulant to be used, the dose of the coagulant and the pH of the water [8,14]. In many scientific studies, it was determined that TOC removal decreased with increasing alkalinity and pH value, and removal efficiency increased with increasing TOC content and amount [15]. ...
Article
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5.8 billion cubic meters of water is drawn from the water resources in Turkey for drinking and potable water network, according to the Turkey Statistical Institute's 2016 Municipal Water Statistics results. 92.9% of this water is treated by conventional treatment methods, 6.1% by advanced treatment techniques and 1% by physical treatment methods. Conventional drinking water treatment plants generally include oxidation, pretreatment, chemical treatment (coagulation flocculation-sludge), filtration and disinfection units. Similar treatment units are used in Sanliurfa drinking water treatment plant which is the subject of the present study. Total Organic Carbon (TOC) is one of the water quality determination methods such as BOD and COD. It refers to organic substances dissolved or suspended in water. With this study; the treatment efficiency of Sanliurfa drinking water treatment plant was evaluated according to the TOC parameter. The TOC removal efficiency performance evaluation of treatment plant was made by comparing experimental data for January-May period. According to this; average efficiency was determined as 28.51%. As a result, this performance value is concluded to be an average treatment efficiency for such conventional drinking water treatment plants.
... Chlorine agents are used in raw water to significantly reduce the charge of pollutants in the pre-chlorination (oxidation) process [3,4]. However, the reaction of chlorine with NOM or micro-contaminants during this process leads to the formation of carcinogenic trihalomethanes (THMs) and haloacetic acids (HAAs) [5][6][7][8]. In the coagulation, flocculation and precipitation units, the turbidity of the water is removed and then the final residues are removed by filtration. ...
... Elimination or reduction of pollution and damages is a major problem. The removal of organic matter by coagulation depends on the amount, nature and structure of the organic matter in the water environment, the coagulant to be used, the dose of the coagulant and the pH of the water [8,14]. In many scientific studies, it was determined that TOC removal decreased with increasing alkalinity and pH value, and removal efficiency increased with increasing TOC content and amount [15]. ...
... NOM in water (i.e. TOC) is a precursor for harmful disinfection byproducts (DBPs) produced during chlorination including potentially carcinogenic trihalomethanes (THMs) and haloacetic acids (HAA s ) (Kim & Yu, 2005;ODriscoll, Sheahan, et al., 2018). DBPs have been reported to be cytotoxic, genotoxic, developmentally toxic and growth inhibitory (Chaves, Guerreiro, Cardoso, Benoliel, & Santos, 2019). ...
... Therefore, in order to minimize these undesirable effects, limiting the concentration of organic compounds in finished water is essential. In a study on estimating THMs in drinking water sources, it was revealed that high fertilizer soils and agricultural land were the most important determinant of THMs in treated waters (ODriscoll, Sheahan, et al., 2018;Portier et al., 2017). Climate change and an increase of precipitation in the Jajrood catchment could lead to leakage of pollutants (agricultural fertilizers, pesticides, etc.) from agricultural lands, places of toxic pollution or streamflow into this catchment. ...
Article
Evaluation of the impact of climate change on water sectors is one of the most important challenges of water resources management in the current century. In this paper, assessment of vulnerability to climate change on total organic carbon (TOC) concentration in the Jajrood catchment in Tehran has been done. The hydroclimatologic parts of the assessment have been done by implementing HYMOD and downscaling of precipitation, temperature and evaporation using statistical downscaling model (SDSM). Three climate change scenarios (RCP 2.6, RCP 4.5 and RCP 8.5) from the Canadian Earth System Model have been used to project climate change (2006 to 2050). Moreover, different linear models were used to model water quality in Latyan Dam and Tehranpars Water Treatment Plant (TWTP). Based on the results, the average annual simulated rainfall under RCP 2.6, RCP 4.5, and RCP 8.5 are 670.2, 658.06 and 650.93 mm, respectively. The projected streamflow under the scenarios were 97%, 90%, and 92%, respectively, more than observation period. The average simulated TOC concentration in influent water was 52.43 (mg/L), which was about seven times more than the averaged observed value (8.78 mg/L). The most important byproduct of the current impact assessment is to define an adaptation action plan, because the TWTP will not be able to provide drinking water standards in this area.
... Ireland has the highest reported THM exceedances in potable water across the European Union (EU) (O'Driscoll et al., 2018). In Ireland, most drinking water is abstracted from surface sources which are more susceptible to high DOC concentrations. ...
... Understanding catchment processes can help alleviate drinking water treatment costs and will form part of the engineered solution to adapting infrastructure to cope with future climate changes (Grayson et al., 2012). In a national assessment of THM exceedances in Irish drinking waters catchments with 'higher peat soil and agricultural land use' were a positive determinant of THM concentrations in treated water (O'Driscoll et al., 2018). Furthermore, in terms of quality NOM characteristic of reprocessed humic organic matter was the prominent component remaining following drinking water treatment. ...
Article
Natural organic matter poses an increasing challenge to water managers because of its potential adverse impacts on water treatment and distribution, and subsequently human health. Projections were made of impacts of climate change on dissolved organic carbon (DOC) in the primarily agricultural Boyne catchment which is used as a potable water supply in Ireland. The results indicated that excluding a potential rise in extreme precipitation, future projected loads are not dissimilar to those observed under current conditions. This is because projected increases in DOC concentrations are offset by corresponding decreases in precipitation and hence river flow. However, the results presented assume no changes in land use and highlight the predicted increase in DOC loads from abstracted waters at water treatment plants. Elsevier Share URL Link To help you and the other authors access and share this work, we have created a Share Link – a personalized URL providing 50 days' free access to the article. Anyone clicking on this link before April 26, 2018 will be taken directly to the final version of your article on ScienceDirect. No sign up, registration or fees are required – they can simply click and read. https://authors.elsevier.com/c/1WggLB8ccgXQk
... NOM in water (i.e. TOC) is a precursor for harmful disinfection byproducts (DBPs) produced during chlorination including potentially carcinogenic trihalomethanes (THMs) and haloacetic acids (HAA s ) (Kim & Yu, 2005;ODriscoll, Sheahan, et al., 2018). DBPs have been reported to be cytotoxic, genotoxic, developmentally toxic and growth inhibitory (Chaves, Guerreiro, Cardoso, Benoliel, & Santos, 2019). ...
... Therefore, in order to minimize these undesirable effects, limiting the concentration of organic compounds in finished water is essential. In a study on estimating THMs in drinking water sources, it was revealed that high fertilizer soils and agricultural land were the most important determinant of THMs in treated waters (ODriscoll, Sheahan, et al., 2018;Portier et al., 2017). Climate change and an increase of precipitation in the Jajrood catchment could lead to leakage of pollutants (agricultural fertilizers, pesticides, etc.) from agricultural lands, places of toxic pollution or streamflow into this catchment. ...
... However, anthropogenic pressures can lead to degradation of the peatland habitats, diminishing raw water quality and resulting in increased water treatment costs. Water quality changes, due to peatland degradation, prove of particular concern due to elevated organic carbon loads and increased risk of disinfection by-products, such as trihalomethanes (THMs), exceeding water quality standards (Chow et al. 2003;O'Driscoll et al. 2018). ...
Article
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Understanding hydrological processes operating on relatively intact blanket bogs provides a scientific basis for establishing achievable restoration targets for damaged sites. A GIS-based hydrological model, developed to assess restoration potential of Irish raised bogs, was adapted and applied to four relatively intact blanket bogs in Ireland. The Modified Flow Accumulation Capacity (MFAC) model utilised high-resolution topographic data to predict surface wetness, based on climatic conditions, contributing catchment and local surface slope. Modifications to MFAC parameters aimed to account for differences in hydrological processes between raised bogs and blanket bogs. Application of a climatic correction factor accounted for variations in effective rainfall between the four study sites, while monitoring of water table levels indicated a log-linear relationship between MFAC values and summer water table levels and range of water table fluctuations. Deviations from the observed relationship between MFAC and water table levels were associated with hydrological pressures, such as artificial drainage or the occurrence of subsurface macropores (peat pipes), which further lowered summer water tables. Despite being effective as a predictor of relative surface wetness, the relationship between MFAC and ecological variables such as Sphagnum spp. cover proved poor, pointing to the impact of past activities and damage caused by anthropogenic pressures. Findings demonstrated MFAC as an effective tool in predicting surface wetness within blanket bog-covered landscapes, thus proving useful to peatland practitioners in planning and prioritising areas for restoration. Supplementary Information The online version contains supplementary material available at 10.1007/s13157-023-01765-5.
... Conversely at lower water ages, the contact time between residual chlorine and NOM would not be long enough to increase the concentration of THMs. Chloroform has the dominant fraction (28.22 μg/L) among the four THMs components at the maximum water age ( Table 2) as observed by earlier researchers [13] [14]. High levels of Chloroform in chlorinated water networks is attributed to the reaction between residual chlorine and NOM, which usually come from personal care products, pharmaceuticals, plasticizers, fragrances, etc. [15]. ...
Article
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Chlorine disinfection in conventional water treatment plants in Egypt is a popular and inexpensive technique for disinfecting raw surface water before distribution to consumers. Nevertheless, the chlorination process in the presence of natural organic matter and decreased water quality due to uncontrollable population results in formation of high concentrations of carcinogenic disinfection by-products, from which trihalomethanes (THMs). In this paper, the water quality of Assiut drinking water network (ADWN) was assessed in terms of THMs studying different water quality parameters. An extended period simulation based on a modelling software WaterGEMS was employed to obtain the critical locations to be examined according to key parameters namely: water age, residual chlorine concentration, water velocity, and type of storage. The study concluded that THMs concentrations from all critical locations in Assiut drinking water network would not exceed the Egyptian regulatory threshold and US Environmental Protection Agency (EPA) guidelines. Even more, an investigated domestic roof tank should be critically operated under a planned scheme of monitoring and maintenance due to its deteriorated water quality.
... This impacts on water quality, which has implications for the water treatment industry, i.e. increased coagulant costs, increased sludge costs, and fouling of network (Ritson et al., 2016, Jennings et al., 2006. Also, lack of, or inadequate removal of DOC by water treatment followed by disinfection can produce harmful by-products, such as total trihalomethanes (TTHM) (O'Driscoll et al., 2018), which are carcinogenic compounds. Although methane emissions reduce following drainage, drainage ditches may still function as methane hotspots in the wider peatland landscape (Peacock et al., 2017). ...
Research
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This synthesis report summarises the detailed scoping report published here: https://mail.thewaterforum.ie/app/uploads/2021/03/Peatlands_Full_Report_Final_Feb2021.pdf This project was funded by Fóram Uisce (The Irish Water Forum).
... A "bottom-up" approach was used based on vulnerability where scenarios were projected by implementing stochastic methods in order to identify the conditions under which a system is vulnerable to climatic change, operations, or infrastructure. (iv) In (O'Driscoll et al., 2018) the causes that led Ireland to become one of the countries in the European Union that frequently exceed the concentrations of Total Trihalomethane (TTHM) in drinking water was researched. At a national level, the relationship of variables such as climate, slope, uptake, disinfection treatments, land use (pastures), presence of peat and other geographical parameters with the TTHM formation was evaluated, using GIS-geographical information system tools. ...
Article
Fresh water, despite being a renewable natural resource, is currently limited and scarce. Its necessity for life and economic growth has led to permanent conflicts of interest. Social and sectoral dynamics regarding water entail conflicts over use, alterations of natural conditions, effects on its availability, quantity and quality. Due to anthropic activities present in watersheds, freshwater systems around the world face the emergence of innumerable chemical substances that hinder their treatment possesses and favor the formation of other compounds. These include disinfection byproducts (DBPs), which are compounds that represent a risk to human health due to its mutagenic and carcinogenic nature. This study conducts a systematic review of the literature concerning DBPs in drinking water supply systems (DWSS). From the research questions formulated in the review, a knowledge gap has been identified, which suggests the problems linked to the appearance of DBPs in treated water, should be addressed within an interdisciplinary and systemic approach. This implies the development of methodological, sociological, ecological and technological processes that allow an understanding of the problem from a holistic and integrative perspective. The occurrence of DBPs in drinking water treatment plants cannot be reduced to the product of chemical reactions between precursors and disinfectant agents such as chlorine; on the contrary, the problem presumes a much more complex origin that requires an analysis of the actions and processes that are carried out in territories and potentiate the deleterious processes in terms of water quality.
... a series of spectroscopy and mass spectrometry techniques have been increasingly applied for effective characterization and monitoring of DOM in wastewater and drinking water treatments ( Phong and Hur 2016 ;Heibati et al., 2017 ;Sgroi et al., 2017 ;Sweetman et al., 2018 ;Truong et al., 2019 ). They provide valuable insights into the variable DOM composition across different water bodies and are effective for tracking the changes of different DOM constituents in a series of treatment processes ( Ly and Hur, 2018 ;O'Driscoll et al., 2018 ;Chen et al., 2020 ;Xiao et al., 2020 ). This review aims to (1) firstly compare the two popularly applied monitoring techniques for DOM (i.e. ...
Article
Dissolved organic matter (DOM) plays a critical role in determining the quality of wastewater and the safety of drinking water. This is the first review to compare two types of popular DOM monitoring techniques, including absorption spectroscopy and fluorescence excitation-emission matrices (EEMs) coupled with parallel factor analysis (PARAFAC) vs. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), for the applications in wastewater and drinking water treatments. The optical techniques provide a series of indices for tracking the quantity and quality of chromophoric and fluorescent DOM, while FT-ICR-MS is capable of identifying thousands of DOM compounds in wastewater and drinking water at the molecule level. Both types of monitoring techniques are increasingly used in studying DOM in wastewater and drinking water treatments. They provide valuable insights into the variability of DOM composition in wastewater and drinking water. The complexity and diversity of DOM highlight the challenges for effective water treatments. Different effects of various treatment processes on DOM are also assessed, which indicates that the information on DOM composition and its removal is key to optimize the treatment processes. Considering notable progress in advanced treatment processes and novel materials for removing DOM, it is important to continuously utilize these powerful monitoring tools for assessing the responses of different DOM constituents to a series of treatment processes, which can achieve an effective removal of DOM and the quality of treated water.
... The reasoned opinion covers all drinking water supply zones administered by Irish Water and the Group Water Scheme Sector as overseen by the National Federation of Group Water Schemes. Higher total THM concentrations in drinking water in the Republic of Ireland have been found to be associated with peat presence, shallow topographical slopes (<5.25%), and higher than average rainfall [43]. Swift remedial action to reduce total THM concentrations is required to address the EC's reasoned opinion. ...
Article
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Source protection is part of a multi-solution approach for the provision of safe drinking water. In the Republic of Ireland, community-led Group Water Schemes (GWS) provide treated drinking water to approximately 69,000 rural households. Between 2009 and 2019, preliminary source protection assessments were undertaken for 70 GWS abstracting from surface water sources to provide physical catchment characterisation and untreated and treated water quality analysis. Catchment areas upstream of abstraction points varied in size, with 51.5% being less than 5 km2 and only 10.7% being larger than 100 km2. The majority (91%) of assessed GWS serve a population of less than 3000 people, and 94% supply less than 1500 m3 per day. Exceedances of the EU Drinking Water Regulations were recorded for 27 parameters, with the greatest number of exceedances due to total trihalomethanes followed by microbial contamination. The most frequent recommendation for improving GWS drinking water quality was associated with managing livestock access to local water bodies. Improving stakeholder engagement represented 38% of all recommendations made. Drinking water source protection measures and catchment-scale actions can be an additional model to assist in the delivery of Integrated Catchment Management and river basin management planning in the Republic of Ireland. For the GWS sector, challenges lie in securing resources to improve both source water and drinking water quality to deliver integrated catchment management plans for source protection.
... Total trihalomethanes were not reported for Ireland and the United Arab Emirates. Upon further investigation, the violation in Ireland was attributed to the presence of peat soil and agricultural land surrounding the catchment, which increased humic acid concentration, leading to the eventual reaction with disinfectant and the increased levels of total trihalomethanes [57]. ...
Article
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Sustaining a reliable and contaminant-free drinking water is becoming an increasing challenge worldwide due to human activity, industrial waste, and agricultural overuse. Surface water is the main source of drinking water around the world. However, groundwater is also becoming increasingly popular, due to its clarity and minimal need for processing to reduce turbidity. Over the years, the demand and growth in the agricultural industry has also been the means of groundwater contamination. Due to the health burden that raw water can pose, water must be processed and purified prior to consumption. Raw water quality can be compromised by physical, chemical (heavy metals and disinfection by-products), and biological contaminants. Biological contaminants can significantly impact immunocompromised populations, while chemical contaminants can impact the growth and development of young children. Although obtaining a steady and high-quality water flow to the general population is an increasing challenge, developed countries have utilized state-of-the-art technologies and techniques to provide contaminant-free water to their citizens. This research aims to provide information about the regulatory parameters, characteristics, and sources of safe drinking water in the world as a model for future use in the developing world. In this, secondary data was used to compare and contrast drinking water quality among countries in the European Union, the United States, Canada, the United Kingdom, Singapore, New Zealand, Australia, Qatar, and the United Arab Emirates. The data indicates that Ireland and the United Kingdom have relatively lower amounts of contaminants in their drinking water. Upon completing this research, it is recommended that countries desiring clean drinking water systems should initiate and invest in programs that control and protect treatment plants, water distribution systems, water sources, and catchments.
... However, it has been observed that free chlorine reacts with organic matter present in water, favoring the formation of disinfection byproducts (DBP), mainly trihalomethanes. These compounds have been considered as carcinogenic substances [3]. To avoid the generation of DBP and to contribute more efficiently to the eradication of waterborne diseases, alternative low-cost but efficient treatments are proposed, which will make it possible to optimize water treatment techniques. ...
Article
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Background In developing countries, death due to diseases caused by fecal-oral ingestion can be avoided by taking action on drinking water issues. Adequate access to water treatment systems to reduce infections is a critical cause. Silver has been used as an antibacterial product, including biomedical applications. Therefore, in this paper, the effect of the chemical speciation of silver from silver-modified zeolite-rich tuffs on the mortality of Escherichia coli (E. coli), Streptococcus faecalis (S. faecalis) and Candida albicans (C. albicans) suspended in aqueous solution was investigated for disinfection purposes.Methods The following aspects were considered to develop the investigation: a) the technique to prepare the modified zeolitic materials, either with ionic silver or silver nanoparticles, which were obtained in two ways: one, with grapefruit extract and the second, by using non-thermal plasma generated in a dielectric barrier discharge reactor of parallel plates; b) the response of the prokaryotes (bacteria) and eukaryote (yeast) microorganisms to disinfectant agents in batch systems; c) the disinfection processes as a function of time to obtain kinetics parameters; and d) the kinetics of the silver release from the silver-modified zeolite-rich tuffs, considering the models of Higuchi and Korsmeyer. The zeolitic materials were characterized by low-vacuum scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS).ResultsThe non-thermal plasma reduced ionic silver is more efficient at generating silver compounds with several oxidation states, which are essential during the microbial inhibition process. For the bacterial (E. coli and S. faecalis), the materials with nanoparticles were efficient to inactivate them. However, the yeast (C. albicans) reaches the total inactivation when the zeolitic material contains ionic silver in the crystalline network.Conclusion The E. coli, S. faecalis and C. albicans survival behavior suspended in aqueous solutions after contact with Ag-modified natural zeolites depends on the chemical speciation of the silver present in these materials, Ag+1 in the case of OAgiZ or nanoparticles of Ago promoted by the grapefruit extract (OAgnpTZ), as well as by non-thermal plasma generated in a dielectric barrier discharge reactor of parallel plates (OAgnpPZ). In general, the concentration of silver in the aqueous solution after the disinfection process cannot exceed the recommended levels established for international organizations. The OAgnpPZ is a potential microbicide agent against E. coli and C. albicans, and the OAgnpTZ for F. faecalis. ARTWORK.
... The main drivers of the acceleration of peatland degradation in the 20th century were associated with drainage for agriculture, peat extraction and afforestation related activities (burning, over-grazing, fertilisation) with a variable scale and severity of impact depending on existing resources in the various countries (O'Driscoll et al. 2018;Cobb, A.R. et al. Dommain et al. 2018;Lamers et al. 2015). ...
Chapter
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This chapter examines the scientific understanding of how climate change impacts land degradation, and vice versa, with a focus on non-drylands. Land degradation of drylands is covered in Chapter 3. After providing definitions and the context (Section 4.1) we proceed with a theoretical explanation of the different processes of land degradation and how they are related to climate and to climate change, where possible (Section 4.2). Two sections are devoted to a systematic assessment of the scientific literature on status and trend of land degradation (Section 4.3) and projections of land degradation (Section 4.4). Then follows a section where we assess the impacts of climate change mitigation options, bioenergy and land-based technologies for carbon dioxide removal (CDR), on land degradation (Section 4.5). The ways in which land degradation can impact on climate and climate change are assessed in Section 4.6. The impacts of climate-related land degradation on human and natural systems are assessed in Section 4.7. The remainder of the chapter assesses land degradation mitigation options based on the concept of sustainable land management: avoid, reduce and reverse land degradation (Section 4.8), followed by a presentation of eight illustrative case studies of land degradation and remedies (Section 4.9). The chapter ends with a discussion of the most critical knowledge gaps and areas for further research (Section 4.10).
... In earlier DBPs surveys, people usually paid more attention to the spatial variations of DBPs in various locations (Krasner et al., 1989;Williams et al., 1997;Krasner et al., 2016;O'Driscoll et al., 2018), but relatively less to the temporal changes of DBPs at a fixed location. It was reported that certain regulated and unregulated DBPs in Canadian distribution systems decreased between autumn and winter but increased to an apex in the summer (Guilherme and Rodriguez, 2014), which served as an example of seasonal variations of DBPs. ...
Article
In order to better understand the occurrence of disinfection byproducts (DBPs) in tap water and their real impacts on consumers, this study made a one-year long survey of the temporal variations of a series of DBPs before and after a point-of-use (POU) treatment facility installed in a building serving for ~300 people. Water samples were collected every week at a fixed location and time for 1 year, and frequent samplings were carried out every 6 h a day for one month at selected seasons, which ultimately amounted to 322 samples. The results show that the concentrations of DBPs were higher in the summer than other seasons, with the lowest DBP levels being observed in spring. Within one week, higher levels of haloacetic acids (HAAs) were identified on weekdays than those on weekends. Diurnally, trihalomethanes, HAAs, and haloacetaldehydes were found to be higher at noon but lower in the evening. Consistent with other studies, the variations of most DBPs were somewhat positively related to the changes of temperature and organic matter, but negatively related to the quantity of free chlorine. With the use of a POU facility, which equips with two activated carbon cartridges and a boiler in sequence, most of DBPs were dramatically reduced, leading to 62-100% lower cytotoxicity for the measured DBPs. The study hence provides a real-water evidence about the DBP occurrences in a typical distribution system endpoint and the efficiency of a typical POU on mitigating DBP risks.
... Contributions of direct water intake were the major route to trihalomethanes. In Ireland a large study in THM was conducted in country and indicated that chloroform contributed to the majority of the THMt in the drinking water supplies and the supply networks contributed to about 30 µg·L −1 of THMt [16]. The THM formation occurs in two steps. ...
... However, it has been observed that free chlorine reacts with organic matter present in water, favoring the formation of disinfection byproducts (DBP), mainly trihalomethanes. These compounds have been considered as carcinogenic substances [3]. To avoid the generation of DBP and to contribute more efficiently to the eradication of waterborne diseases, alternative low-cost but efficient treatments are proposed, which will make it possible to optimize water treatment techniques. ...
Article
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Bacteria that survive the pollutant mixing conditions of the upper basin of the Lerma river (CARL) require a specialized metabolism for survival. Under this postulation, sediment was taken from three sites of the CARL as a source of bacteria resistant to Cr +6. At the site identified as Lerma, greater variability of species was found in the group of selected bacteria that reduced Cr +6. In Tultepec, the highest population of Cr +6 reducing bacteria was isolated. Six strains with different morphological and biochemical characteristics were isolated from the sediments. These strains tolerated concentrations up to 1000 mg L -1 of Cr +6 in liquid media. Also they reduced Cr +6 to Cr +3 in percentages between 7 and 40, following 7 days, supplemented with 200 mg L -1 of Cr +6. The strains studied were Gram negative and showed a minimum inhibitory concentration greater than that found in other studies. The transformation capacity of each strain in descending order were: F, A, B, C, E and D. The kinetics of reduction of strain F showed the highest transformation of Cr +6 to Cr +3, obtaining a reduction of 33.59 % at 12 days. The biomass of strain F was not affected by the presence of Cr +6. It is important to note that the medium itself represented a reduction of Cr +6 (17.21 %). The use of the API-20E kit was helpful in determining some biochemical reactions of strains, however, this identification was not conclusive because it presented low percentages of similarity (83.1 to 90.7 %). These strains represent a potential of biotechnology for use in treatment systems to reduce Cr +6 to Cr +3, and even in trials of other heavy metals.
Article
This study reports the trihalomethanes generated during disinfection within the water distribution network of Delhi, India. For 12 months study period tap water samples were collected (n = 216) from the command areas of nine water treatment plants to provide a comprehensive picture of spatial and seasonal variation of trihalomethanes in the city. The mean concentrations of chloroform, bromodichloromethane, dibromochloromethane, bromoform were 34.62 ± 13.09 μg/l, 25.39 ± 11.75 μg/l, 15.83 ± 9.66 μg/l, 1.74 ± 1.51 μg/l respectively, the total trihalomethanes concentration ranged between 11.41–175.54 μg/l. Chloroform was prevalent accounting 45% in total trihalomethanes followed by bromodichloromethane, dibromochloromethane, bromoform accounting 33%, 20%, and 2% respectively. Trihalomethanes concentrations were found to be increasing during summer season and got decreased in the winter and post-monsoon season. Total trihalomethanes levels were found to be highest at Chandrawal water treatment plant command area (85.35–148.38 μg/l) and lowest at Okhla water treatment plant command area (11.41–63.38 μg/l). In many samples trihalomethanes concentrations were discovered to be higher than the allowable limit specified by Indian Standards. A strong relationship between trihalomethanes formation with total organic carbon (r = 0.934) and residual chlorine (r = 0.801) accentuate its capability for monitoring disinfection by-products in the distribution network. Results showed that considerable levels of trihalomethanes are generated in the study area, therefore the competent authorities must take the appropriate steps to regularly monitor the trihalomethanes in drinking water. The findings of this study may help to provide operators with invaluable information on drinking water quality and open up several chances to enhance water quality management.
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Preprint
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A GIS-based hydrological model, developed to assess restoration potential of Irish raised bogs, was applied to four blanket bogs located across the island of Ireland. The model utilised high-resolution topographic data to predict surface/near-surface hydrological processes, based on climatic conditions, contributing catchment and local surface slope; these provided a prediction of relative surface wetness across each blanket bog catchment. Modifications to the raised bog modelling approach aimed to account for differences in hydrological processes. Application of a climatic correction factor, accounted for climatic variations between the four study sites, while monitoring of water table levels indicated a log-linear relationship between model outputs and summer water tables (median and D90 levels (i.e., water levels equalled or exceeded for 90% of the time)). Higher model outputs were associated with areas where the water table remains closer to the ground surface and a lower range of fluctuations during summer months. Deviations from model outputs were associated with hydrological pressures, such as artificial drainage or the occurrence of peat pipes, which lowered summer water tables. Model outputs also showed significant correlation with peat thickness. Despite being effective as a predictor of hydrological conditions, correlation with ecological variables such as Sphagnum spp. cover proved poor. This reflected the variation in vegetation within and between sites, pointing to the impact of past activities and damage caused by anthropogenic pressures. Findings demonstrate the model as an effective tool in simulating hydrological conditions within blanket bog-covered landscapes, thus proving useful to peatland practitioners in planning and prioritising restoration.
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Extant literature has demonstrated that conventional water treatment processes especially in developing countries struggle in completely removing detrimental organic loads. Emerging research delineates nanomaterials such as nanoscale zero valent iron (nZVI) to have excellent performance in organic matter removal from aqueous media. In this work, nZVI particles were prepared from the liquor of commercially available green tea and supported on kaolin (K‐nZVI) and investigated as an adsorbent for natural organic matter (NOM) sequestration from aquatic media. Further, the asymmetric ceramic membrane was prepared by incorporating the developed adsorbent on a concrete support for the removal of NOM. A Fenton cleaning strategy was developed to mitigate fouling. The Brunauer–Emmett–Teller (BET) results revealed the developed adsorbent surface area was greater compared to raw kaolin (27.07 and 11.64 m³ g⁻¹, respectively). The scanning electron microscopy (SEM) imagery of the developed adsorbent showed the particle staking was presented as paper slices of varying sizes, an indication of dispersed particles with characteristic plate‐like fragments. The synthesized membrane exhibited a pHZPC value of 4.79 ± 0.03. This meant at pH above 4.79 ± 0.03, the membrane would be negatively charged, and conversely at pH below the pHZPC value. Membrane fouling due to bovine serum albumin (BSA) deposition showed a 50% flux decline in the first 60 min, coinciding with the rapid adsorption capacity within the same time frame. The optimal cleaning parameters of pH (4.5) and H2O2 (5 mM) gave the best flux recovery rates. This work demonstrated an efficient Fenton cleaning strategy to regenerate the developed membrane.
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This report is part of a detailed scoping study to: -Provide an in depth literature review of peatlands in Ireland covering the following topics: 1) rewetting degraded peatlands; 2) carbon sequestration; 3) social value of peatlands; 4) alternative management options. -Provide strategic guidance and identify resources for future integrated management of peatlands. This project was produced for and funded by Fóram Uisce (The Irish Water Forum). the report can also be found here: https://mail.thewaterforum.ie/app/uploads/2021/03/Peatlands_Full_Report_Final_Feb2021.pdf
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Background and purpose: Jajrood River is one of the major drinking water supply rivers in Tehran, so, the effects of climate change on its quantitative and qualitative resources are highly important. This study aimed at investigating the effect of climate change on organic carbon removal in Jajrood basin. Materials and methods: In this descriptive cross-sectional study, CanESM2 general circulation model and SDSM (version 5.3) downscaling model were used for simulating climatic data and HYMOD model was used to simulate runoff in Jajrood catchment. Climate change scenarios RCP2.6, RCP4.5, and RCP8.5 were simulated for 2006-2050. Stepwise regression and linear regression were used in MATLAB R2017a to model the qualitative data. Results: According to findings, the temperature of this basin will be about 2.25°C warmer than the base period. Rainfall and runoff in the whole catchment will increase by about 10% and 93% and the concentrations of total organic carbon of the inlet to the treatment plant will be about three times higher than the base period which will increase the load on carbon in different units of the treatment plant. Conclusion: Increased rainfall caused by washing the upstream agricultural lands and temperature increase due to elevated rate of bioactivity lead to deterioration of the quality of water entering the dam and increase the organic carbon entering the treatment plant. On the other hand, Tehranpars water treatment plant with its current capacity and efficiency will not meet the standards of drinking water in terms of organic carbon.
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Technical Report
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Ireland has an unacceptably high number of drinking water supplies that exceed the parametric value of 100 μg L-1 for total trihalomethanes (THMs) and has been reporting the highest non-compliance with respect to total THMs in drinking water across the 27 EU Member States. Trihalomethanes are a possible carcinogen formed when chlorine, used to disinfect drinking water reacts with natural organic matter (NOM) also present in the drinking water. Furthermore, there is no scientific evidence available for Ireland on the naturally occurring organic toxin, ptaquiloside, which is derived from bracken ferns. This report presents findings from a literature review and case studies on THMs and ptaquiloside in Irish drinking water.
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It is well known that natural organic matter (NOM) is the major precursor of disinfection by-products (DBPs) when inadequately removed NOM reacts with the disinfectant during chlorination and chloramination. Special interest in the DBP precursors is justified as it is essential to understand the reactivity and character of the precursors responsible for the formation of DBPs. This is vital in order to develop processes that will enhance precursor removal during drinking water treatment. The aim of this study was to investigate the impact of the characteristics of NOM within an oligotrophic water source on the formation of trihalomethanes (THMs) during drinking water treatment at Rand Water. Specific ultraviolet absorbance (SUVA) and molecular size distribution (MSD) were the main NOM characterisation techniques utilised during this study. The MSD was investigated by making use of high-performance size-exclusion chromatography (HPSEC). The MSD results showed a significant correlation between the high-molecular-weight (HMW) fraction of NOM and TTHM formation, specifically during the summer months. The positive correlation existing between SUVA and full scale NOM removal indicates that SUVA can be used to indicate NOM treatability during water treatment. A link between chloroform formation and the HMW fraction of NOM was also observed; however, the formation of bromodichloromethane (BDCM) was not due to the HWM fraction, as indicated by a weak regression coefficient. The results displayed are an indication that the aromatic fraction of NOM was the main precursor to TTHM formation, more prominently during summer.
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This manual sets out the protocols and methodologies for all aspects of the National Survey of Upland Habitats (NSUH). Uplands form Ireland’s largest expanses of semi-natural landscape and support numerous habitats of high nature conservation value that require conservation under Irish and EU law. For the purposes of this survey upland habitats are defined as unenclosed areas of land over 150 m and contiguous areas of related habitat that extend below this altitude. The main objectives of the NSUH are to map upland habitats and vegetation and to assess the conservation status of upland habitats listed in Annex I of the EU Habitats Directive. The habitat maps and survey data generated by this survey are required for conservation management purposes at an individual site level and for the identification of appropriate national conservation strategies, as well as to contribute data towards fulfillment of Ireland’s reporting obligations to the EU Commission on conservation status of Annex I habitats.
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Internationally, water management is moving from the traditional top-down approach to more integrated initiatives focussing on community-led action. With inadequacies in previous engagement initiatives undertaken through the first cycle of River Basin Management Planning for the EU Water Framework Directive (WFD), the Republic of Ireland has only recently embraced this bottom-up approach. The attempted introduction of national charging for domestic water use in 2015 has resulted in significant public disquiet and protest movements against the national government. In April 2015 we undertook a survey of current opinion on water management and community engagement initiatives in the Republic of Ireland and the United Kingdom. A total of 520 survey responses identified that although freshwater bodies are important in peoples’ lives, respondents were typically unaware of global initiatives such as Integrated Water Resources Management and Integrated Catchment Management. Overall, 81% of respondents did not feel included in decisions about their water environment despite an overwhelming 95% believing that local communities should have a say in how the water environment is managed. However, only 35.1% of respondents stated that they would be willing to attend local water management engagement initiatives. Rather than supporting individual gain, respondents identified social gains for the local community as avenues for increasing local involvement in water initiatives. In the Republic of Ireland, a water engagement initiative that implements the national framework local delivery model should be developed and implemented. This would 1) contribute to the second round of WFD River Basin Management Planning; 2) facilitate stronger connections between local communities and their water environment; and 3) foster bottom-up initiatives that empower communities regarding local water management issues.
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Trihalomethanes (THMs) are conditionally carcinogenic compounds formed during chlorine disinfection in water treatment processes around the world. THMs occur especially when source waters are subject to marine influences, high and-or regular precipitation, and elevated levels of organic matter. THMs formation is then rooted in geographic, operational and climatic factors, the relative importance of which can only be derived from large datasets and may change in the future. Ninety three full-scale Scottish water treatment plants (WTPs) were assessed from Jan 2011 to Jan 2013 to identify factors that promote THMs formation. Correlation analysis showed that ambient temperature was the primary THMs formation predictor in potable water (r² = 0.66, p < 0.05) and water distribution systems (r² = 0.43, p = 0.04), while dissolved organic carbon (r² = 0.55, p < 0.001) and chloride (indicating marine influence; r² = 0.41, p < 0.001) also affected THMs formation. GIS mapping of median THMs levels indicated brominated THMs were most prevalent in coastal areas and on islands. This real-world dataset confirms both geographic and climatic factors are key to THMs formation. If ambient temperatures increase, THMs control will become more challenging, substantiating concerns about the impact of global warming on water quality.
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See paper at http://rdcu.be/nmwn This paper analyses a Twitter dataset to explore water governance and stakeholder engagement during the introduction of domestic water charges in Ireland. The results highlight active Twitter use during the analysis period, reflective of widespread protest centred on a new utility, Irish Water. The analysis shows protest activities were dispersed and not cohesive, with tweets largely focused on economic and political issues and not on the provision of a sustainable water supply. The findings extend our understanding of these events and provide some insights into the role of social media in water governance and stakeholder engagement issues in an Irish and wider context.
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Organic soils are widespread in Ireland and vulnerable to degradation via drainage for agriculture. The soil-landuse combination of pasture on organic soils may play a disproportionate role in regional C dynamics but is yet to receive study. Fluvial C fluxes and labile organic fractions were determined for two such sites at nested field (c.4 ha) and subcatchment scales (>40 ha); one relatively dry and nutrient rich, the other wetter and nutrient poor. Field scale flux from the nutrient poor site over 2 years was 38.9 ± 6.6 g C m−2 yr−1 with DIC > DOC > POC at 57, 32 and 11 % respectively, and 72 % DIC was comprised of above equilibrium CO2. At the nutrient rich site, which overlies limestone geology, field scale export over an individual year was 90.4 g C m−2 with DIC > DOC > POC at 49, 42 and 9 %, but with 90 % DIC as bicarbonate. By comparison with the nutrient poor site, the magnitude and composition of inorganic C exports from the nutrient rich site implied considerable export of soil-respiratory C as bicarbonate, and lower evasion losses due to carbonate system buffering. Labile DOC determined using dark incubations indicated small fractions (5–10 %) available for remineralisation over typical downstream transit times of days to weeks. These fractions are probably conservative as photolysis in the environment can increase the proportion of labile compounds via photocleavage and directly remineralise organic matter. This study demonstrates that monitoring at soil–water interfaces can aid capture of total landscape fluvial fluxes by precluding the need to incorporate prior C evasion, although rapid runoff responses at field scales can necessitate high resolution flow proportional, and hydrograph sampling to constrain uncertainty of flux estimates.
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Accounting for greenhouse gas (GHG) emissions and removals in managed ecosystems has generally focused on direct land–atmosphere fluxes, but in peatlands a significant proportion of total carbon loss occurs via fluvial transport. This study considers the composition of this ‘waterborne carbon’ flux, its potential contribution to GHG emissions, and the extent to which it may change in response to land-management. The work describes, and builds on, a methodology to account for major components of these emissions developed for the 2013 Wetland Supplement of the Intergovernmental Panel on Climate Change. We identify two major components of GHG emissions from waterbodies draining organic soil: i) ‘on site’ emissions of methane (and to a lesser extent CO2) from drainage ditches located within the peatland; and ii) ‘off site’ emissions of CO2 resulting from downstream oxidation of dissolved and particulate organic carbon (DOC and POC) within the aquatic system. Methane emissions from ditches were found to be large in many cases (mean 60 g CH4 m−2 year−1 based on all reported values), countering the view that methane emissions cease following wetland drainage. Emissions were greatest from ditches in intensive agricultural peatlands, but data were sparse and showed high variability. For DOC, the magnitude of the natural flux varied strongly with latitude, from 5 g C m−2 year−1 in northern boreal peatlands to 60 g C m−2 year−1 in tropical peatlands. Available data suggest that DOC fluxes increase by around 60 % following drainage, and that this increase may be reversed in the longer-term through re-wetting, although variability between studies was high, especially in relation to re-wetting response. Evidence regarding the fate of DOC is complex and inconclusive, but overall suggests that the majority of DOC exported from peatlands is converted to CO2 through photo- and/or bio-degradation in rivers, standing waters and oceans. The contribution of POC export to GHG emissions is even more uncertain, but we estimate that over half of exported POC may eventually be converted to CO2. Although POC fluxes are normally small, they can become very large when bare peat surfaces are exposed to fluvial erosion. Overall, we estimate that waterborne carbon emissions may contribute about 1–4 t CO2-eq ha−1 year−1 of additional GHG emissions from drained peatlands. For a number of worked examples this represented around 15–50 % of total GHG emissions.
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Calibration period and control area method were used to study the impact of forest tree harvesting on the dissolved organic carbon (DOC) export from drained peatland forests using data from 17 harvested and five control catchments. The results indicated highly increased DOC exports; during the first 3 years following harvesting, the average extra export ranged from over 200 kg ha−1 in nutrient-poor ombrotrophic to over 400 kg ha−1 in fertile minerotrophic peatland forest sites. The results indicated that a high iron (Fe) content in peat, as well as a high nitrogen (N) content and a low carbon (C)N ratio, are the site characteristics that contribute to large harvest-induced DOC exports. The effect of Fe is probably caused by the reduction of Fe in previously aerobic peat layers that have undergone harvest-induced water level rise and thus enhanced the DOC export, and the effects of the peat N and CN ratio indicate that the impacts of harvesting on DOC are the greatest from the sites with a high overall microbial activity. The calibration period/control area analysis revealed a high uncertainty in our data, the 95 % confidence intervals for average DOC exports overlapping between the groups with differing site characteristics. Given the uncertainties involved in our data, we conclude that significant changes in water colour and other water characteristics associated with large DOC inputs may be expected, where harvested forests on peatlands cover large proportions of catchments of small lakes and rivers.
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Peatlands are important sources of fluvial carbon. Previous research has shown that riverine dissolved organic carbon (DOC) concentrations are largely controlled by soil type. However, there has been little work to establish the controls of riverine DOC within blanket peatlands that have not undergone major disturbance from drainage or burning. A total of 119 peatland catchments were sampled for riverine DOC and water colour across three drainage basins during six repeated sampling campaigns. The topographic characteristics of each catchment were determined from digital elevation models. The dominant vegetation cover was mapped using 0.5m resolution colour infrared aerial images, with ground-truthed validation revealing 82% accuracy. Forward and backward stepwise regression modelling showed that mean slope was a strong (and negative) determinant of DOC and water colour in blanket peatland river waters. There was a weak role for plant functional type in determining DOC and water colour. At the basin scale, there were major differences between the models depending on the basin. The dominance of topographic predictors of DOC found in our study, combined with a weaker role of vegetation type, paves the way for developing improved planning tools for water companies operating in peatland catchments. Using topographic data and aerial imagery it will be possible to predict which tributaries will typically yield lower DOC concentrations and which are therefore more suitable and cost-effective as raw water intakes. Copyright © 2015 Elsevier B.V. All rights reserved.
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This study assesses the influence of the total organic carbon (TOC) content, chlorine quantity, water temperature, bromide ion concentration, and seasonal variations on trihalomethanes (THMs) formation potential (THMFP) in Dez River water in Iran. The water temperature and TOC content had a significant effect on THMFP. Further, the experimental results showed that increasing the concentration of bromide ions enhance the formation of dibromochloromethane and bromoform. It was found that the THMFP in Dez River water during summer times was relatively higher than 100 µg/L, maximum contaminant level for THMs in drinking water. By increasing the reaction time until 80 h, the THMFP was gradually increased and reached to 177.4 µg/L. The most abundant fraction of natural organic matter in the river was hydrophobic acid fraction (49.4 μg/L). Overall, our study demonstrated that however the THMFP of Dez River water was relatively high but a usual waterworks could effectively reduce THMFP.
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Exposure to disinfection by-products (DBPs) has been demonstrated to impair male reproductive health in animals, but human evidence is limited and inconsistent. To examine the association between exposure to drinking water DBPs and semen quality in a Chinese population. We recruited 2,009 men seeking semen analysis from the Reproductive Center of Tongji Hospital in Wuhan, China between April 2011 and May 2012. Each man provided a semen sample and a urine sample. Semen samples were analyzed for sperm concentration, sperm motility, and sperm count. As a biomarker of exposure to drinking water DBPs, trichloroacetic acid (TCAA) was measured in urine samples. The mean (median) urinary TCAA concentration was 9.58 (7.97) μg/L (interquartile range, 6.01 to 10.96 μg/L). Compared to men with urine TCAA in the lowest quartile, increased adjusted ORs were estimated for below-reference sperm concentration in men with TCAA in the second and fourth quartile (OR = 1.79; 95% CI: 1.19, 2.69 and OR = 1.51; 95% CI: 0.98, 2.31, respectively), for below-reference sperm motility in men with TCAA in the second and third quartile (OR = 1.46; 95% CI: 1.12, 1.90 and OR = 1.30; 95% CI: 1.00, 1.70, respectively), and for below-reference sperm count in men with TCAA in the second quartile (OR 1.62; 95% CI: 1.04, 2.55). Non-monotonic associations with TCAA quartiles were also estimated for semen parameters modeled as continuous outcomes, though significant negative associations were estimated for all quartiles above the reference level for sperm motility. Our findings suggest that exposure to drinking water DBPs may contribute to decreased semen quality in humans.
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Dissolved organic carbon (DOC) concentrations have increased in many sites in Europe and North America in recent decades. High DOC concentrations can damage the structure and functions of aquatic ecosystems by influencing water chemistry. This study investigated the spatial and seasonal variation of DOC concentrations in Irish streams across 55 sites at seven time occasions over 1 year (2006/2007). The DOC concentrations ranged from 0.9 to 25.9 mg/L with a mean value of 6.8 and a median value of 5.7 mg/L and varied significantly over the course of the year. The DOC concentrations from late winter (February: 5.2 ± 3.0 mg/L across 55 sites) and early spring (April: 4.5 ± 3.5 mg/L) had significantly lower DOC concentrations than autumn (October: mean 8.3 ± 5.6 mg/L) and early winter (December: 8.3 ± 5.1 mg/L). The DOC production sources (e.g., litterfall) or the accumulation of DOC over dry periods might be the driving factor of seasonal change in Irish stream DOC concentrations. Analysis of data using stepwise multiple linear regression techniques identified the topographic index (TI, an indication of saturation-excess runoff potential) and soil conditions (organic carbon content and soil drainage characteristics) as key factors in controlling DOC spatial variation in different seasons. The TI and soil carbon content (e.g., soil organic carbon; peat occurrence) are positively related to DOC concentrations, while well-drained soils are negatively related to DOC concentrations. The knowledge of spatial and seasonal variation of DOC concentrations in streams and their drivers are essential for optimum riverine water resources management.
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An online repository of published organic fluorescence spectra has been developed, which can be searched for quantitative matches with any set of unknown spectra. It fills a critical gap by increasing access to measured and modelled (PARAFAC) spectra, and linking across studies and systems to reveal "global" fluorescence trends. Fluorescence spectroscopy offers an inexpensive, non-destruc-tive method for obtaining sensitive measurements of a diverse group of organic compounds that contain uorophores. This technology is now widely used to characterise naturally-occur-ring organic matter in natural and articial aquatic systems with the purpose of understanding how the uorescent frac-tion of carbon is partitioned between different organic matter fractions, and inferring the processes responsible for its formation and removal. 1–5 With Excitation–Emission Matrix (EEM) spectroscopy, uorescence emission is measured over a range of excitation wavelengths to produce three-dimensional uorescence landscapes (Fig. 1). Each EEM represents total uorescence from an unknown number of underlying uo-rophores which in ideal conditions uoresce independently following Beers Law, but under non-ideal conditions may interact. 6 Over the past ten years it has become common practice to decompose EEM datasets mathematically using PARAllel FACtor analysis (PARAFAC). 7–9 PARAFAC reduces the EEM dataset into a small number of building blocks – referred to as 'underlying components' – each with a characteristic excitation and emission spectrum (Fig. 1). Each EEM in a dataset is modelled by a simple recipe in which the same building blocks are combined in varying amounts, reecting their variable concentrations. There are now well over 100 published PARAFAC models of dissolved and natural organic matter (both referred to hereaer as NOM) and over 500 published PARAFAC components. 9,10
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Go to this link for a free e-print http://www.tandfonline.com/eprint/wcaFwT4rdBWRqe76GczT/full In the Republic of Ireland, peatlands cover an estimated 20% of the land area and have been widely utilised over the centuries for energy production, agriculture, forestry and horticultural production. Current estimates suggest that only a small proportion of Irish peatlands are in a natural condition, and that the remainder are either moderately or severely damaged. In this paper, we reviewed carbon (C) studies for the major peatland land uses in Ireland and have estimated that at the national level, emissions from Irish peatlands and related activities (e.g. combustion, horticulture) are around 3 Mt C each year to the atmosphere. However, large uncertainties are associated with this value (1.3–4.7 Mt C yr−1) due to a paucity of field studies for some peatland land uses (particularly cutover peatlands). Mitigation measures to reduce national emissions from peatlands could include: (1) a stronger enforcement approach to protect and enhance the C store in natural peatlands, (2) the rewetting / restoration of degraded peatlands to reduce emissions and create suitable conditions for C sequestration and (3) the use of alternative non-peat sources for energy production and horticulture use.
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PARAllel FACtor analysis (PARAFAC) is increasingly used to decompose fluorescence excitation emission matrices (EEMs) into their underlying chemical components. In the ideal case where fluorescence conforms to Beers Law, this process can lead to the mathematical identification and quantification of independently varying fluorophores. However, many practical and analytical hurdles stand between EEM datasets and their chemical interpretation. This article provides a tutorial in the practical application of PARAFAC to fluorescence datasets, demonstrated using a dissolved organic matter (DOM) fluorescence dataset. A new toolbox for MATLAB is presented to support improved visualisation and sensitivity analyses of PARAFAC models in fluorescence spectroscopy.
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Objectives: Disinfection by-products (DBPs) have been associated with adverse semen outcomes in laboratory animals, although the evidence for trihalomethanes (THMs) is limited. Three small epidemiological studies found little evidence for an association between DBPs and adverse semen outcomes in humans. Using data from a large case-referent study (Chemicals and Pregnancy Study, Chaps-UK), we investigated the association between total THM (TTHM), chloroform and total brominated THMs and sperm concentration, percent motile sperm and motile sperm concentration (MSC). Methods: Chaps-UK recruited men from 13 fertility clinics in nine urban centres across England and Wales between 1999 and 2002. We linked modelled THM concentrations in water zones to semen quality data for 642 cases (men with low MSC) and 926 referents (other men investigated for infertility), based on the men's residence during semen sampling. We assessed risk of low MSC in relation to DBP exposure using continuous THM concentrations. A secondary analysis investigated continuous outcomes (MSC, sperm concentration and percent motile sperm). Results: In the case-referent analysis there was little evidence of elevated risk associated with chloroform, total brominated THM or TTHM concentration after adjustment (OR per 10 µg/L TTHM 1.01; 95% CI 0.91 to 1.12). Similarly, there was no significant effect of THMs on the continuous outcomes. Conclusions: In the largest study to date on DBPs in public water supplies, and semen quality we found that concentrations of THMs were not associated with poor semen quality. Large-scale investigation of other DBPs (eg, haloacetic acids) and other semen quality parameters (eg, sperm morphology and/or sperm DNA integrity) is recommended.
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Few epidemiological studies that have assessed the relation between water disinfection by-products (DBPs) and the risk of stillbirth provide inconsistent results. The objective was to assess the relation between exposure to water disinfection by-products and the risk of stillbirth. We conducted a population-based case-control study of 3,289 cases of stillbirth and a random sample of 32,890 control subjects from 396,049 Taiwanese newborns in 2001-2003 using information from the Birth Registry and Waterworks Registry in Taiwan. We compared the risk of stillbirth in four disinfection by-product exposure categories based on the levels of total trihalomethanes (TTHMs) representing high (TTHMs 20+ µg/L), medium (TTHMs 10-19 µg/L), low exposure (TTHMs 5-9 µg/L), and 0-4 µg/L as the reference category. In addition, we conducted a meta-analysis of the results from the present and 5 previous studies focusing on stillbirth. In logistic regression analysis adjusting for gender, maternal age, plurality, conception of season and population density of the municipality where the mother lived during pregnancy, the odds ratio (OR) for stillbirth was 1.10 (95% CI 1.00-1.21) for medium exposure and 1.06 (95% 0.96-1.17) for high exposure compared to reference category. In the meta-analysis, the summary odds ratio for stillbirth (1.11, 95% CI: 1.03, 1.19) was consistently elevated. The present study is consistent with the hypothesis that the risk of stillbirth is related to prenatal exposure to disinfection by-products. This finding on stillbirth is consistent with previous epidemiologic studies, which strengthens the weight of evidence.
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Dissolved organic matter (DOM) is a complex and poorly understood mixture of organic polymers that plays an influential role in aquatic ecosystems. In this study we have successfully characterised the fluorescent fraction of DOM in the catchment of a Danish estuary using fluorescence excitation–emission spectroscopy and parallel factor analysis (PARAFAC). PARAFAC aids the characterisation of fluorescent DOM by decomposing the fluorescence matrices into different independent fluorescent components. The results reveal that at least five different fluorescent DOM fractions present (in significant amounts) in the catchment and that the relative composition is dependent on the source (e.g. agricultural runoff, forest soil, aquatic production). Four different allochthonous fluorescent groups and one autochthonous fluorescent group were identified. The ability to trace the different fractions of the DOM pool using this relatively cheap and fast technique represents a significant advance within the fields of aquatic ecology and chemistry, and will prove to be useful for catchment management.
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Fluorescence data of replicate samples obtained from different fluorescence spectrometers or by the same spectrometer but with different instrument settings can have great intensity differences. In order to compare such data an intensity calibration must be applied. Here we explain a simple calibration method for fluorescence intensity using only the integrated area of a water Raman peak. By applying this method to data from three different instruments, we show that it is possible to remove instrument-dependent intensity factors, and we present results on a unified scale of Raman units. The method presented is a rapid and simple approach suitable for routine measurements with no need for hazardous chemicals.
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To explore the use of routinely collected trihalomethane (THM) measurements for epidemiological studies. Recently there has been interest in the relation between byproducts of disinfection of public drinking water and certain adverse reproductive outcomes, including stillbirth, congenital malformations, and low birth weight. Five years of THM readings (1992--6), collected for compliance with statutory limits, were analysed. One water company in the north west of England, divided into 288 water zones, provided 15,984 observations for statistical analysis. On average each zone was sampled 11.1 times a year. Five year, annual, monthly, and seasonal variation in THMs were examined as well as the variability within and between zones. Between 1992 and 1996 the total THM (TTHM) annual zone means were less than half the statutory concentration, at approximately 46 microg/l. Differences in annual water zone means were within 7%. Over the study period, the maximum water zone mean fell from 142.2 to 88.1 microg/l. Mean annual concentrations for individual THMs (microg/l) were 36.6, 8.0, and 2.8 for chloroform, bromodichloromethane (BDCM), and dibromochloromethane (DBCM) respectively. Bromoform data were not analysed, because a high proportion of the data were below the detection limit. The correlation between chloroform and TTHM was 0.98, between BDCM and TTHM 0.62, and between DBCM and TTHM -0.09. Between zone variation was larger than within zone variation for chloroform and BDCM, but not for DBCM. There was only little seasonal variation (<3%). Monthly variation was found although there were no consistent trends within years. In an area where the TTHM concentrations were less than half the statutory limit (48 microg/l) chloroform formed a high proportion of TTHM. The results of the correlation analysis suggest that TTHM concentrations provided a good indication of chloroform concentrations, a reasonable indication of BDCM concentrations, but no indication of DBCM. Zone means were similar over the years, but the maximum concentrations reduced considerably, which suggests that successful improvements in treatment have been made to reduce high TTHM concentrations in the area. For chloroform and BDCM, the main THMs, the component between water zones was greater than variation within water zones and explained most of the overall exposure variation. Variation between months and seasons was low and showed no clear trends within years. The results indicate that routinely collected data can be used to obtain exposure estimates for epidemiological studies at a small area level.
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Concentrations of dissolved organic carbon (DOC) in freshwaters have increased significantly in Europe and North America, but the driving mechanisms are poorly understood. Here, we test if the significant increase in TOC (total organic carbon, 90-95% DOC) in three acid-sensitive catchments in Norway of 14 to 36% between 1985 and 2003 is related to climate, hydrology, and/or acid deposition. Catchment TOC export increased between 10 and 53%, which was significant at one site only. The seasonal variation in TOC was primarily climatically controlled, while the deposition of SO4 and NO3--negatively related to TOC--explained the long-term increase in TOC. We propose increased humic charge and reduced ionic strength--both of which increase organic matter solubility--as mechanistic explanations for the statistical relation between reduced acid deposition and increased TOC. Between 1985 and 2003, ionic strength decreased significantly at all sites, while the charge density of TOC increased at two of the sites from 1-2 meq g(-1) C to about 5 meq g(-1) C and remained constant at the third site at 5 meq g(-1) C. The solubility of organic matter is discussed in terms of the pH-dependent deprotonation of carboxylic groups and the ionic strength-dependent repulsion of organic molecules.
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Rising dissolved organic carbon (DOC) concentrations in many upland UK catchments represents a challenge for drinking water companies, in particular due to the role of DOC as a precursor in the formation of trihalomethanes (THMs). Whereas traditionally, the response of drinking water companies has been focussed on treatment processes, increasingly, efforts have been made to better understanding the role of land use and catchment processes in affecting drinking water quality. In this study, water quality, including DOC and THM formation potential (THMFP) was assessed between the water source and finished drinking water at an upland and a lowland catchment. Surprisingly, the lowland catchment showed much higher reservoir DOC concentrations apparently due to the influence of a fen within the catchment from where a major reservoir inflow stream originated. Seasonal variations in water quality were observed, driving changes in THMFP. However, the reservoirs in both catchments appeared to dampen these temporal fluctuations. Treatment process applied in the 2 catchments were adapted to reservoir water quality with much higher DOC and THMFP removal rates observed at the lowland water treatment works where coagulation-flocculation was applied. However, selectivity during this DOC removal stage also appeared to increase the proportion of brominated THMs produced. Copyright © 2015. Published by Elsevier B.V.
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These authors recommend that water treatment plant designers and operators use an integrated approach to optimize the collective effects of the treatment train for removing NOM. Because it is not practical to analyze for each individual chemical compound present in natural organic matter (NOM), surrogate characterization methods were south that could identify interrelationships between NOM and its teratability. Source‐related and seasonal differences, effects of ozonation and coagulation on NOM, characterization of NOM in sequential unit processes including granular activated carbon, and aspects of bromide‐NOM interactions are explored. Whereas coagulants remove NOM intact, particularly higher‐molecular‐weight fractions, ozone converts humic to nonhumic material, resulting in NOM fractions that colud be difficult to remove by subsequent of separation techniques unles the bromide concentration is equalized in the individual fractions.
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Dissolved organic carbon (DOC) concentrations were measured in streams draining 42 small (0.6-37.2 km2) catchments located in the Appalachian Uplands and St. Lawrence Lowlands. Weekly sampling from mid-April to late-November in 4 catchments containing <1% wetland revealed DOC concentrations in streams averaging 3.5-7.2 mg.L-1 with significant positive relationships to discharge. In 4 catchments containing 15-69% wetland, average DOC concentrations in streams ranged from 14.5-40.0 mg.L-1; there was no significant relationship to discharge. DOC concentrations in streams draining the 42 catchments showed consistent relationships of varying strength with the variable percent wetland in the catchment. Soil drainage rating, percent forest, mean catchment slope, and catchment area provided little improvement in the regression model. Separating the catchments into Uplands and Lowlands improved the predictive power of the regression model for the upland catchments. The poor relationships between DOC and percent wetland in the lowland catchments are attributed to the dry summer during sampling and extensive modification of land use, such as the drainage of wetlands and agriculture. -from Authors
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A groundwater recharge map has been created for the Republic of Ireland. This provides important baseline information for multiple purposes: aquifer water balance assessments using simple lumped models or distributed numerical groundwater models; assessment of the impact of groundwater abstractions as required under the European Water Framework Directive; and delineation of source protection zones. The groundwater recharge map is derived from existing hydrogeological and meteorological spatial datasets. The main hydrogeological controls on groundwater recharge include the permeability and thickness of superficial deposits (mainly tills in Ireland), the presence of saturated soils, and the ability of the underlying aquifer to accept percolating waters. Combinations of these factors are assessed, and a 'recharge coefficient' is established for different hydrogeological scenarios. To produce the groundwater recharge map, the geographic information system layer containing the recharge coefficients is multiplied by the effective rainfall. The recharge map is finally modified to take into account areas where the natural recharge capacity of the underlying aquifer is less than the estimated groundwater recharge potential. Originally drafted in 2005, the present map includes refined recharge coefficient estimates, improved representation of wet soils over gravel aquifers, and a full national coverage of full subsoil permeability and groundwater vulnerability mapping. There are a number of assumptions made in creating the groundwater recharge map (notably, only direct (diffuse) recharge is taken into account) and there are limitations of precision associated with the input datasets. For reasons of scale and generalization to a national coverage, the map is useful for giving regional estimates of recharge but these, in many cases, will need to be refined by site-specific studies.
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Dissolved organic carbon (DOC) concentrations in surface waters have increased across much of Europe and North America, with implications for the terrestrial carbon balance, aquatic ecosystem functioning, water treatment costs and human health. Over the past decade, many hypotheses have been put forward to explain this phenomenon, from changing climate and land management to eutrophication and acid deposition. Resolution of this debate has been hindered by a reliance on correlative analyses of time series data, and a lack of robust experimental testing of proposed mechanisms. In a 4 year, four‐site replicated field experiment involving both acidifying and deacidifying treatments, we tested the hypothesis that DOC leaching was previously suppressed by high levels of soil acidity in peat and organo‐mineral soils, and therefore that observed DOC increases a consequence of decreasing soil acidity. We observed a consistent, positive relationship between DOC and acidity change at all sites. Responses were described by similar hyperbolic relationships between standardized changes in DOC and hydrogen ion concentrations at all sites, suggesting potentially general applicability. These relationships explained a substantial proportion of observed changes in peak DOC concentrations in nearby monitoring streams, and application to a UK‐wide upland soil pH dataset suggests that recovery from acidification alone could have led to soil solution DOC increases in the range 46–126% by habitat type since 1978. Our findings raise the possibility that changing soil acidity may have wider impacts on ecosystem carbon balances. Decreasing sulphur deposition may be accelerating terrestrial carbon loss, and returning surface waters to a natural, high‐DOC condition.
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Dissolved organic carbon (DOC) is a recognized indicator of natural organic matter (NOM) in surface waters. The aim of this paper is twofold: to evaluate the impact of geophysical characteristics, climate and ecological zones on DOC concentrations in surface waters and, to develop a statistical model to estimate the regional variability of these concentrations. In this study, multilevel statistical analysis was used to achieve three specific objectives: (1) evaluate the influence of climate and geophysical characteristics on DOC concentrations in surface waters; (2) compare the influence of geophysical characteristics and ecological zones on DOC concentrations in surface waters; and (3) develop a model to estimate the most accurate DOC concentrations in surface waters. The case study involved 115 catchments from surface waters in the Province of Quebec, Canada. Results showed that mean temperatures recorded 60days prior to sampling, total precipitation 10days prior to sampling and percentages of wetlands, coniferous forests and mixed forests have a significant positive influence on DOC concentrations in surface waters. The catchment mean slope had a significant negative influence on DOC concentrations in surface waters. Water type (lake or river) and deciduous forest variables were not significant. The ecological zones had a significant influence on DOC concentrations. However, geophysical characteristics (wetlands, forests and slope) estimated DOC concentrations more accurately. A model describing the variability of DOC concentrations was developed and can be used, in future research, for estimating DBPs in drinking water as well evaluating the impact of climate change on the quality of surface waters and drinking water.
Article
Organic matter (OM) causes many problems in drinking water treatment. It is difficult to monitor OM concentrations and character during treatment processes due to its complexity. Fluorescence spectroscopy is a promising tool for online monitoring. In this study, a unique dataset of fluorescence excitation emission matrixes (EEMs) (n = 867) was collected from all treatment stages of five drinking water treatment plants (WTPs) situated in diverse locations from subtropical to temperate climate. The WTPs incorporated various water sources, treatment processes and OM removal efficiencies (DOC removal 0%-68%). Despite these differences, four common fluorescence PARAFAC components were identified for characterisation of OM concentration and treatability. Moreover, fluorescence component ratios showed site-specific statistically significant correlations with OM removal, which contrasted with correlations between specific UV absorbance at 254 nm (SUVA) and OM removal that were not statistically significant. This indicates that use of fluorescence spectroscopy may be a more robust alternative for predicting DOC removal than UV spectroscopy. Based on the identified fluorescence components, four optical locations were selected in order to move towards single wavelength online OM monitoring.
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Although membrane filtration is a promising technology in the field of drinking water treatment, persistent membrane fouling remains a major disadvantage. For more efficient operation, causative agents of membrane fouling need to be identified. Membrane fouling can be classified into physically reversible and irreversible fouling on basis of the removability of the foulants by physical cleaning. Four types of natural organic matter (NOM) in river water used as a source of drinking water were fractionated into hydrophobic and hydrophilic fractions, and their potential to develop irreversible membrane fouling was evaluated by a bench-scale filtration experiment together with spectroscopic and chromatographic analyses. In this study, only dissolved NOM was investigated without consideration of interactions of NOM fractions with particulate matter. Results demonstrated that despite identical total organic carbon (TOC), fouling development trends were significantly different between hydrophilic and hydrophobic fractions. The hydrophobic fractions did not increase membrane resistance, while the hydrophilic fractions caused severe loss of membrane permeability. These results were identical with the case when the calcium was added to hydrophobic and hydrophilic fractions. The largest difference in NOM characteristics between hydrophobic and hydrophilic fractions was the presence or absence of macromolecules; the primary constituent causing irreversible fouling was inferred to be “biopolymers”, including carbohydrates and proteins. In addition, the results demonstrated that the extent of irreversible fouling was considerably different depending on the combination of membrane materials and NOM characteristics. Despite identical nominal pore size (0.1 μm), a polyvinylidene fluoride (PVDF) membrane was found to be more rapidly fouled than a PE membrane. This is probably explained by the generation of strong hydrogen bonding between hydroxyl groups of biopolymers and fluorine of the PVDF membrane. On the basis of these findings, it was suggested that the higher fouling potential of the hydrophilic fraction of the dissolved NOMs from various natural water sources are mainly attributed to macromolecules, or biopolymers.
Article
Enhanced Coagulation is a new regulatory requirement in the United States aimed at removing TOC by coagulation thereby controlling formation of disinfection byproducts. Coagulation principles are summarized for alum coagulation of natural organic matter (NOM). Negatively charged NOM creates a coagulant demand for positively charged Al species resulting in a stoichiometric relationship between the alum dosage and the raw water DOC that is pH dependent. The paper addresses coagulation with a broader view than Enhanced Coagulation, termed multiple objective coagulation. In general the objectives include: 1) to maximize particle and turbidity removals by downstream solid-liquid separation, 2) to maximize TOC and DBP precursor removals, 3) to minimize residual coagulant, 4) to minimize sludge production, and 5) to minimize operating costs. Optimum coagulation conditions are those that maximize pathogen removals, produce low turbidities and particle counts, and minimize residual Al. It is shown, for treatment of waters of low alkalinity, that the optimum alum dosage selected to minimize UV absorbance with strict pH control produced excellent treatment for turbidity, pathogens, and NOM. Full scale plant data are used to demonstrate a dual coagulation strategy of alum and cationic polymer that reduces sludge production and overall operating costs compared to alum alone.
Article
A review of the major issues in UK upland catchment water quality research is presented. For each issue, an attempt is made to identify why it is perceived as a problem and to examine its extent and historical trends. Causal mechanisms are discussed and possible control methods investigated. Issues examined include acidification, mobilization of toxic metals, discoloration, nutrient loss and sedimentation.
Article
It is essential to have suitable tools able to trace the fate of manure organic matter in the environment to assess whether manure disposal on the soils of catchments could affect the organic quality of rivers. Sterol compounds – mainly expressed as C29+28/C27 and 5β/C27 ratios – have been shown to be specific molecular tracers of pig, dairy and poultry manures in soils. The objective of this study was to measure C29+28/C27 and 5β/C27 ratios in five Brittany rivers (Elorn, Yar, Léguer, Min Ran and Couesnon) draining agricultural catchments receiving massive annual inputs of pig, poultry and dairy manures and compare these ratios with ratios published for enriched soils and manure samples. The particulate organic fractions from the studied rivers yielded steroid signatures typical of animal manures. More specifically, a stanol compound diagnostic of pig slurry – the 5β-stanol known as coprostanol – was found to be very widespread, with particularly high concentrations in one of the rivers (Elorn). The C29+28/C27 and 5β/C27 ratios of the particulate fractions of the rivers were compared with ratios measured directly in pig, dairy and poultry manure samples, as well as with the breeding activities on river catchments. These comparisons show that the steroid profiles of the five investigated rivers correlate closely with the types of manure (i.e. pig, poultry or dairy) spread on soils in their catchments. For instance, the C29+28/C27 and 5β/C27 ratios in the Elorn river are similar to the values typical of pig slurry (e.g. 5β/C27 >4); compared with other catchments, the soils in this area receive by far the largest amount of pig slurry. By contrast, the Yar river drains a catchment receiving only poultry and dairy manures, and its soils exhibit C29+28/C27 and 5β/C27 ratios similar to those of dairy and poultry manures (e.g. 5β/C27 ∼1). Thus, this study indicates that the organic quality of rivers is modified in catchments where there is intense manure spreading on soils. It also provides evidence that rivers draining areas receiving different manure types may exhibit differences in the long-term evolution of their OM content. Indeed, two of the investigated river catchments receive dominantly dairy and poultry manure, and exhibit clear long-term upward trends in OM. On the other hand, one catchment receiving high proportions of pig slurry clearly shows a long-term downward trend in OM contents. A survey of the literature shows that the relative amount of OM and N received by soils in agricultural catchments could be the key parameter in determining the direction of the long-term OM trend of the river, rather than the absolute amount and/or type of manure that is applied to the soil. In any case, the present study suggests that sterol/stanol compounds may be of diagnostic value in determining whether a stream or a river is undergoing contamination by manure-derived organic matter.
Article
Data were gathered on the presence of disinfection by-products (DBPs) in drinking water and on the impact of treatment processes on DBP formation and control. Thirty-five water treatment facilities were selected to provide a broad range of source water qualities and treatment processes. Trihalomethanes were the largest class of DBPs detected (on a weight basis) in this study, with haloacetic acids being the next most significant DBP fraction. Formaldehyde and acetaldehyde, by-products of ozonation, were also demonstrated to be produced by chlorination. Cyanogen chloride was found to be preferentially produced in chloraminated water. Se recogieron datos de la presencia de sub-productos de la desinfección (DBPs) en aguas de bebida y sobre el impacto de los procesos de tratamiento en la formación y control de los DBPs. Treinta y cinco plantas de tratamiento fueron seleccionadas para obtener un amplio rango tanto de calidad del agua cruda, como de los procesos de tratamiento. Los trihalometanos fueron la clase de DBPs más grande detecatada (sobre la base de peso) en este estudio, y los ácidos haloacéticos fueron la fracción siguiente más significante de DBPs. Se comprobó que los formaldehidos y los acetaldehidos, sub-productos de la ozonización, también eran producidos por la clorinación. El producto principal de la aplicación de cloraminas fue el cianuro de cloro.
Article
Determining the spatial extent of peat soils is essential for measuring soil carbon (C) stocks. The Derived Irish Peat Map (DIPM) estimated the spatial extent of peat soils as 13.8% of the national area. The DIPM was derived from the Peatland Map of Ireland, CORINE and cover database (CORINE) 1990 and the General Soil Map of Ireland. This paper presents an updated version, the Derived Irish Peat Map Version 2 (DIPMV2), using the same rules-based decision tree methodology, but CORINE 2000 and the Indicative Soil Map of Ireland (ISMI) replaced CORINE 1990 and the General Soil Map of Ireland. The DIPMV2, a best-estimate, illustrates that peat soils occur more extensively than previously mapped, especially in the ‘drumlin belt’ of counties Cavan, Monaghan and Louth. The producer, user and overall accuracies are 88, 91 and 85%, respectively. This is an improvement on the DIPM (87, 84, and 85%). The DIPMV2, estimates that peat soils cover 1,466,469 ha, or 20.6%, of the national land area. The DIPM methodology may provide a long-term tool for updating national peat soil map data. It can be concluded that data for peat soils will become more important because peat has high carbon density and modifications to peat soils have implications for climate change.
Article
Application of over-winter green cover (e.g. cover crops) as a measure for reducing nitrate losses from tillage land has been frequently investigated, especially in the unsaturated zone. Monitoring of groundwater is less common in these studies. Studies on groundwater responses to different land treatments can be challenging because they can be influenced by various conditions, such as recharge, seasonal variations, and aquifer properties, often occurring at different time scales than surface water processes. The aim of this study was to evaluate groundwater nitrate (NO(3)(-)N) and dissolved organic carbon (DOC) concentration responses to different over-winter green covers: mustard, natural regeneration and no cover. A field experiment was designed and run for three years on tillage land underlain by a vulnerable sand and gravel aquifer in the south-east of Ireland. Results showed that over-winter green cover growth on tillage land can be an effective measure to reduce groundwater NO(3)(-)N concentrations. A significant decrease in groundwater NO(3)(-)N concentrations was observed under the mustard cover compared to no cover. All treatments, including no cover, showed a decline in groundwater NO(3)(-)N concentrations over time. A significant increase in groundwater DOC was also observed under the mustard cover. Although the overall groundwater DOC concentrations were low, the increased DOC occurrence in groundwater should be accounted for in carbon balances and could potentially enhance groundwater denitrification in cases where aquifer conditions may favour it.
Article
Estimating losses of dissolved carbon (C) and nitrogen (N) via groundwater in an agricultural system provides insights into reducing uncertainties in the terrestrial C and N balances. In addition, quantification of dissolved nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) in groundwaters beneath agricultural systems is important for global greenhouse gas (GHG) budgets. Dissolved C (DC: dissolved organic carbon (DOC) + CO2-C + CH4-C) and dissolved nitrogen (DN: NO3−-N + NH4+ + NO2−-N + N2O-N + N2) in groundwater were measured in two low permeability (<0.02 m d−1) and two high permeability (>0.05 m d−1) aquifers in Ireland. Groundwater in multilevel piezometers was sampled monthly over two years. Mean groundwater discharge to surface water was higher in 2009 (587–836 mm) than in 2010 (326–385 mm). Dissolved C and N delivery to surface water via groundwater caused substantial losses of terrestrial C and N. The extent of delivery was site specific and depended on N input, recharge and aquifer permeability. Mean dissolved N losses ranged from 8–12% of N input in low permeability to 27–38% in high permeability aquifers. The dominant fraction of DN was NO3−-N (84–90% of DN) in high permeability aquifers and N2 (46–77% of DN) in low permeability aquifers. Indirect N2O emissions via groundwater denitrification accounted for 0.03–0.12% of N input, which was equivalent to 3–11% of total N2O emissions. Dissolved C loss to surface waters via groundwater was not significant compared to total carbon (TC) content of the topsoil (0.06–0.18% of TC). Site characteristics contributed greatly to the distribution of N between NO3−-N and dissolved N gases, N2O and N2. Indirect GHG emissions from groundwater were an important part of farm nutrient budgets, which clearly has implications for national GHG inventories.
Article
Recharge to an aquifer can be estimated by first calculating the effective rainfall using a soil moisture budgeting technique, and then by applying a recharge coefficient to indicate the proportion of this effective rainfall that contributes to groundwater recharge. In the Republic of Ireland, the recharge coefficient is determined mainly by the permeability and thickness of the superficial deposits (subsoils) that overlie the country's aquifers. The properties of these subsoils also influence groundwater vulnerability, and a methodology has been developed for determining the recharge coefficient using the groundwater vulnerability classification. The results of four case studies have been used to develop a quantified link between subsoil permeability, aquifer vulnerability, recharge and runoff. Recharge and runoff coefficients are each classed into three groupings: high, intermediate and low. A high recharge coefficient equates to a low runoff coefficient, and vice versa. A GIS-based tool enables preliminary estimates of recharge to be made using these recharge coefficient groupings. Potential recharge is calculated as the product of effective rainfall and recharge coefficient. The actual recharge is then calculated taking account of the ability of the aquifer to accept the available recharge. The methodology could be applied to other temperate climate zones where the main aquifers have a substantial covering of superficial deposits.
Article
Studies were conducted to develop correlation between nanofiltration (NF) membrane fouling, feed water quality, and membrane characteristics. The water quality of the three seasonal NF feed samples was characterized by UV, DOC, HPLC-0UVA-DOC, XAD, IC and ICP. Surface charge, specific flux variation at different pH and ionic strengths, molecule weight cut-off (MWCO), and functional groups of the NF 200 membrane surface were determined. The extent of fouling was significantly dependent on water quality, membrane properties, and operational conditions. Higher flux decline was observed at high DOC, high divalent cations, high alkalinity and low temperature. Temperature strongly affected the specific flux and natural organic matter (NOM) rejection. Inorganic salt precipitation was proven by FTIR, X-ray diffraction, X-ray fluorescence and SEM. NOM fouling was observed during long run pilot tests at relatively high temperature while scale fouling was observed at both high and low temperatures. Due to the decrease in solubility of CaCO3(s) and CaSO4(s) at high temperature, homogeneous crystallization occurred that led to less flux decline. At low temperature, in spite of the increased solubility, heterogeneous crystallization with NOM absorption was observed. This is due to an increase in pH and formation of nucleus components induced by a temperature decrease. Heterogeneous crystallization caused more significant flux decline than homogeneous crystallization.
Article
This study was conducted to determine the main sources of dissolved organic carbon (DOC) and disinfection byproduct (DBP) precursors to the McKenzie River, Oregon (USA). Water samples collected from the mainstem, tributaries, and reservoir outflows were analyzed for DOC concentration and DBP formation potentials (trihalomethanes [THMFPs] and haloacetic acids [HAAFPs]). In addition, optical properties (absorbance and fluorescence) of dissolved organic matter (DOM) were measured to provide insight into DOM composition and assess whether optical properties are useful proxies for DOC and DBP precursor concentrations. Optical properties indicative of composition suggest that DOM in the McKenzie River mainstem was primarily allochthonous--derived from soils and plant material in the upstream watershed. Downstream tributaries had higher DOC concentrations than mainstem sites (1.6 +/- 0.4 vs. 0.7 +/- 0.3 mg L(-1)) but comprised < 5% ofmainstem flows and had minimal effect on overall DBP precursor loads. Water exiting two large upstream reservoirs also had higher DOC concentrations than the mainstem site upstream of the reservoirs, but optical data did not support in situ algal production as a source of the added DOC during the study. Results suggest that the first major rain event in the fall contributes DOM with high DBP precursor content. Although there was interference in the absorbance spectra in downstream tributary samples, fluorescence data were strongly correlated to DOC concentration (R2 = 0.98), THMFP (R2 = 0.98), and HAAFP (R2 = 0.96). These results highlight the value of using optical measurements for identifying the concentration and sources of DBP precursors in watersheds, which will help drinking water utilities improve source water monitoring and management programs.
Article
The fluorescent properties of dissolved organic matter (DOM) are often studied in order to infer DOM characteristics in aquatic environments, including source, quantity, composition, and behavior. While a potentially powerful technique, a single widely implemented standard method for correcting and presenting fluorescence measurements is lacking, leading to difficulties when comparing data collected by different research groups. This paper reports on a large-scale interlaboratory comparison in which natural samples and well-characterized fluorophores were analyzed in 20 laboratories in the U.S., Europe, and Australia. Shortcomings were evident in several areas, including data quality-assurance, the accuracy of spectral correction factors used to correct EEMs, and the treatment of optically dense samples. Data corrected by participants according to individual laboratory procedures were more variable than when corrected under a standard protocol. Wavelength dependency in measurement precision and accuracy were observed within and between instruments, even in corrected data. In an effort to reduce future occurrences of similar problems, algorithms for correcting and calibrating EEMs are described in detail, and MATLAB scripts for implementing the study's protocol are provided. Combined with the recent expansion of spectral fluorescence standards, this approach will serve to increase the intercomparability of DOM fluorescence studies.
Article
Natural organic matter (NOM) in water samples from a drinking water treatment train was characterized using fluorescence excitation emission matrices (F-EEMs) and parallel factor analysis (PARAFAC). A seven component PARAFAC model was developed and validated using 147 F-EEMs of water samples from two full-scale water treatment plants. It was found that the fluorescent components have spectral features similar to those previously extracted from F-EEMs of dissolved organic matter (DOM) from diverse aquatic environments. Five of these components are humic-like with a terrestrial, anthropogenic or marine origin, while two are protein-like with fluorescence spectra similar to those of tryptophan-like and tyrosine-like fluorophores. A correlation analysis was carried out for samples of one treatment plant between the maximum fluorescence intensities (F(max)) of the seven PARAFAC components and NOM fractions (humics, building blocks, neutrals, biopolymers and low molecular weight acids) of the same sample obtained using liquid chromatography with organic carbon detection (LC-OCD). There were significant correlations (p < 0.01) between sample DOC concentration, UVA(254), and F(max) for the seven PARAFAC components and DOC concentrations of the LC-OCD fractions. Three of the humic-like components showed slightly better predictions of DOC and humic fraction concentrations than UVA(254.) Tryptophan-like and tyrosine-like components correlated positively with the biopolymer fraction. These results demonstrate that fluorescent components extracted from F-EEMs using PARAFAC could be related to previously defined NOM fractions and that they could provide an alternative tool for evaluating the removal of NOM fractions of interest during water treatment.
Article
Warmer conditions may be to blame for the exodus of peatland carbon to the oceans.
Article
Dissolved organic carbon (DOC) concentrations in 22 UK upland waters have increased by an average of 91% during the last 15 years. Increases have also occurred elsewhere in the UK, northern Europe and North America. A range of potential drivers of these trends are considered, including temperature, rainfall, acid deposition, land-use, nitrogen and CO2 enrichment. From examination of recent environmental changes, spatial patterns in observed trends, and analysis of time series, it is suggested that DOC may be increasing in response to a combination of declining acid deposition and rising temperatures; however it is difficult to isolate mechanisms based on monitoring data alone. Long-term DOC increases may have wide-ranging impacts on freshwater biota, drinking water quality, coastal marine ecosystems and upland carbon balances. Full understanding of the significance of these increases requires further knowledge of the extent of natural long-term variability, and of the natural "reference" state of these systems.
The Chlorine Demand Characteristics of Irish Water Supplies: Process Design Implications for Disinfection and THM Formation. Chartered Institution of Water and Environmental Management
  • T Casey
  • P Kearney
  • H Kerr
Casey, T., Kearney, P., Kerr, H., 2012. The Chlorine Demand Characteristics of Irish Water Supplies: Process Design Implications for Disinfection and THM Formation. Chartered Institution of Water and Environmental Management, London. http://www.engineersireland.ie/EngineersIreland/media/SiteMedia/grou ps/societies/water-enviro/Chlorine-Demand-Characteristics-of-Irish-Water-Su pplies.pdf?ext¼.pdf. (Accessed 9 October 2017).
National primary drinking water regulations: stage 2 disinfectants and disinfection byproducts rule
S. Environmental Protection Agency, 2006. National primary drinking water regulations: stage 2 disinfectants and disinfection byproducts rule. Fed. Regist. 71, 387e493.