A modeling system for drinking water sources and its application to Jiangdong Reservoir in Xiamen city

Drinking water sources are highly valued by authorities for safeguarding the life of a city. Models are widely applied as important and effective tools in the management of water sources. However, it is difficult to apply models in water source management because water managers are often not equipped with the professional knowledge and operational skills necessary for making use of the models. This paper introduces a drinking water source simulation and prediction system that consists of a watershed model, a hydrological model and a water quality model. This system provides methods and technical guidance for the conventional management of water sources and emergency water event response. In this study, the sub-models of the system were developed based on the data of the Jiangdong Reservoir in Xiamen, and the model validation was based on local monitoring data. The hydrological model and water quality model were integrated by computer programming, and the watershed model was indirectly integrated into the system through a network platform. Furthermore, three applications for Jiangdong Reservoir water protection utilizing the system were introduced in this paper, including a conventional simulation, an emergency simulation, and an emergency measures evaluation.     

Linking fate model in freshwater and PBPK model to assess human internal dosimetry of B(a)P associated with drinking water

In the present study, we demonstrate an integrated modeling approach for predicting internal tissue concentrations of chemicals by coupling a multimedia environmental model and a generic physiologically based pharmacokinetic (PBPK) model. A case study was designed for a region situated on the Seine river watershed, downstream of the Paris megacity, and for benzo(a)pyrene emitted from industrial zones in the region. In this case study, these two models are linked only by water intake from riverine system for the multimedia model into human body for the PBPK model. The limited monitoring data sets of B(a)P concentrations in bottom sediment and in raw river water, obtained at the downstream of Paris, were used to re-construct long-term daily concentrations of B(a)P in river water. The re-construction of long-term series of B(a)P level played a key role for the intermediate model calibration (conducted in multimedia model) and thus for improving model input to PBPK model. In order to take into account the parametric uncertainty in the model inputs, some input parameters relevant for the multimedia model were given by probability density functions (PDFs); some generic PDFs were updated with site-specific measurements by a Bayesian approach. The results of this study showed that the multimedia model fits well with actual annual measurements in sediments over one decade. No accumulation of B(a)P in the organs was observed. In conclusion, this case study demonstrated the feasibility of a full-chain assessment combining multimedia environmental predictions and PBPK modeling, including uncertainty and sensitivity analyses.     

Implementing nanoparticles for competitive drinking water purification

Environmental Chemistry Letters - The implementation of nanotechnology in drinking water treatment is a very promising field for applied research. A major part of this effort focuses on the...     

Targeting arsenic-safe aquifers for drinking water supplies

At present, 70 countries worldwide are affected by groundwater contamination by arsenic (As) released from predominantly geogenic sources. Consequently, the As problem is becoming a global issue. The option to target As-safe aquifers, which uses geological, geochemical, hydrogeological, morphological and climatic similarities to delimit As-safe aquifers, appears as a sustainable mitigation option. Two pilot areas, Meghna Flood Plain in Matlab Upazila, representative of Bengal Delta in Bangladesh, and Río Dulce Alluvial Cone, representing a typical aquifer setting in the Chaco-Pampean Plain in Argentina groundwater As occurrence, were compared. In rural Bangladesh, As removal techniques have been provided to the population, but with low social acceptance. In contrast, “targeting As-safe aquifers” was socially accepted in Bangladesh, where sediment color could be used to identify As-safe aquifer zones and to install safe wells. The investigation in Argentina is more complex because of very different conditions and sources of As. Targeting As-safe aquifers could be a sustainable option for many rural areas and isolated peri-urban areas.     

Ecological compensation based on willingness to accept for conservation of drinking water sources

Ecological compensation is a powerful environmental economic tool for environmental protection in areas where drinking water sources are located. We established an ecological compensation accounting system based on respondents’ willingness to accept (WTA). In this system, stakeholder preferences and the factors that influence them can be gauged effectively using logit and tobit models. We applied this accounting system to ecological compensation for the Miyun Reservoir, Beijing, China. The average WTA value for Miyun Reservoir residents was approximately 1186 CNY per family in 2012, which could be set as a suitable compensation standard, since it is slightly higher than the local protection cost. Thus, the annual total ecological compensation could be 58.73 million CNY. Distance from the reservoir, job types, and attitude to environmental protection were variables with significant effects on WTA. In addition, trends for individual preferences were identified via an analysis of key influential factors. The results suggest some useful information for establishing ecological compensation mechanisms for conservation of drinking water sources. Suggestions include popularizing the concept and meaning of ecological compensation among residents, setting different compensation levels based on distance from the reservoir, considering the requirements of farmers, and taking various in-kind and out-of-kind compensation approaches.     

广州市饮用水中挥发性有机物的研究

饮用水中的挥发性有机化合物（VOCs）来源于水源水受到的环境污染或是在净化消毒工艺处理工程中反应产生的副产物,可对人体健康造成极大的危害。改革开放以来,广州人口和经济得到突飞猛进的发展,也带来了包括饮用水安全在内的诸多严重的社会和环境问题。虽然饮用水中VOCs的研究已经得到越来越多的重视,但是目前对广州市饮用水中挥发性有机物的研究还鲜有报道。本文在广州市中心城区选取15个不同位置的采样点进行了自来水水样采集,并利用吹扫-捕集-气相色谱-质谱（GC-MS）联用系统分析技术测定水中 VOCs 的种类和三卤甲烷的质量浓度。结果表明,广州市中心城区的自来水中VOCs有20种,以三卤甲烷（THMs）和芳香烃类为主,占了所检出的物质总量的78%以上。THMs中四种化合物（氯仿、一溴二氯甲烷、二溴一氯甲烷、溴仿）的检出率达100%,总三卤甲烷的平均质量浓度为46.46μg· L-1,最大值为53.31μg· L-1,最小值39.91μg· L-1。根据2006版国家饮用水标准,四种三卤甲烷质量浓度均低于标准限值,符合标准要求。对市面上一般的瓶装水的研究发现,瓶装水中三卤甲烷的质量浓度非常低,总三卤甲烷平均质量浓度仅为1.47μg·L-1,约是自来水中质量浓度的1/30。为了解温度及煮沸对自来水中 THMs 质量浓度的影响,本研究设计了实验进行探究。结果发现加热至沸腾过程中,THMs质量浓度随温度升高而升高,而沸腾后THMs骤降,煮沸5 min可降低水中约95%的THMs,接近瓶装水中THMs质量浓度。     

Applying chemical sedimentation process in drinking water treatment plant to address the emergent arsenic spills in water sources

Arsenic (As) spills occurred more frequently and sometimes polluted water sources in recent years in China. It is as urgent need to develop emergency treatment technologies to address the arsenic threat for large-scale water treatment plants. In response, we developed a chemical sedimentation technology to remove arsenic contaminants for water treatment plants. Bench-scale experiments were conducted to investigate the efficiency of arsenic removal and the influencing factors of the chemical sedimentation treatment process. The influencing factors included the choice and dosage of coagulants, the valence of arsenic and pH value of solution. The As(V) contaminants can be almost completely removed by ferric or alum coagulants. The As(III) contaminants are more recalcitrant to chemical sedimentation, 75% for ferric coagulant and 40% for alum coagulant. The quantitative results of arsenic removal load by different ferric or alum coagulants were presented to help determine the parameters for arsenic treatment technology. The dominant mechanism for arsenic removal is static combination, or adsorption of negative arsenic species onto positive ferric hydroxide or alum hydroxide flocs. The efficiency of this treatment technology has also been demonstrated by a real production test in one water treatment plant with arsenic-rich source water and one emergency response. This technology was verified to be quick to set-up, easy to operate and highly efficient even for high concentration of arsenic.     

Interfacial solar steam generation by wood-based devices to produce drinking water: a review

Environmental Chemistry Letters - Freshwater supply is declining in the context of climate change, pollution, and soil salinization, calling for sustainable methods to produce drinking water. For...     

Urinary arsenic methylation profile in children exposed to low arsenic levels through drinking water

There is a lack of information on arsenic metabolism in children exposed chronically to low levels of arsenic (<50 µg L^?1). The objective of this study was to determine the methylation profile of urinary arsenic metabolites in children exposed to low-level concentrations of arsenic via their drinking water. A cross-sectional study was undertaken in 50 children from four towns in the Yaqui Valley, Sonora, with total arsenic values of 39.9, 16.8, 7.3, and 5.5 µg L^?1 in their drinking water, respectively. First morning void samples were analyzed for inorganic-As (InAs), mono and dimethyl arsenic (MMA and DMA). The total arsenic excreted in urine ranged from 23.1 to 99.1 µg L^?1 and these levels did not vary by sex. Children with the highest level of total arsenic in their drinking water excreted the highest amount in urine and the length of residence and age also had significant contribution. Children with a lower range of arsenic exposure (16.8–5.5 µg L^?1) had similar amounts of arsenic in urine with values of 23.1, 28.2, and 32.6 µg L^?1, respectively. DMA had the highest proportion in urine (52.1–74.7%), followed by InAs (16.3–34.9%) and MMA (4.4–8.4%). Compared to other reports, these children excreted a low %MMA (6.1%), and children from the towns with the lowest levels of arsenic had the highest %InAs and the lowest %DMA. This variability in arsenic methylation was partially explained by arsenic concentration in drinking water, years of residence and age, and may reflect genetic differences or more contribution from different exposure routes. In conclusion, our results show that at low levels of exposure the children's ability to metabolize InAs did not have a linear association with the levels of arsenic, and overall children from the Yaqui Valley excrete a lower %MMA than expected.     

Techno-economic analysis for the electrocoagulation of fluoride-contaminated drinking water

Electrocoagulation (EC) technique was adopted for the treatment of fluoride-containing drinking water in a 3?L capacity batch reactor. Experimental investigation was carried out to observe the effect of different operating parameters, such as initial fluoride concentration, current density, inter-electrode distance, on the removal of fluoride from the fluoride-rich drinking water. Aluminum flat sheet was used as the electrode material. It was observed that with an increase in current density, percentage removal of fluoride increased. It was seen that at electrode distance of 0.005?m, removal of fluoride attained its maximum compared to the other performances obtained at different inter-electrode distances. Life time of the aluminum electrodes was estimated from the electrode corrosion observed during the experiment. Total operating cost was estimated as a combination of energy cost and electrode cost. The total operating cost was evaluated as 0.38?US$?m^?3 to remove fluoride from the solution with an initial fluoride concentration 10?mg?L^?1. Characterizations of the electrochemically generated by-products were carried out by powder X-ray diffraction, Fourier transform infra-red Raman spectroscopy, scanning electron microscopy image and corresponding elemental analysis.     

Malaysian households' drinking water practices: A case study

Malaysia has abundant water resources and adequate rainfall and yet the nation has water shortages and water quality problem. Various measures have been taken by the government to address water issues but, in spite of these, quantity and quality of drinking water is still one of the main concerns of Malaysian consumers today. An exploratory study was undertaken to determine the level of awareness of respondents on water issues, assess their perception on drinking water quality, and identify measures undertaken by households to improve drinking water quality and to determine sustainable water practices. A cross-sectional research design, utilizing a survey was conducted among urban residents of Seremban town. Data showed that each household had a mean of five members, with an average household income of RM3788.00 (US$1000). The respondents were Chinese (70%), Indian (23%) and Malay (7%). The majority of respondents rated the quality of water supplied to their house as poor (70%), while 16% rated it very poor. The respondents indicated that colour, odour and taste were the main problems with their tap water. Due to the poor tap water quality perceived by respondents, most took additional measures to improve its quality. Most (85%) purchased domestic water filters, 41% boiled water and 17% bought bottled water. The reasons for purchasing water were: concern for health, perception of poor tap water quality, and increasing water contamination and pollution in the country. Almost a quarter of respondents that had water filters mentioned the convenience because they did not have to boil water. Sustainable use of water by respondents was moderate, with a mean of 2.9 on a scale of 1 (never) to 4 (all the time). Some aspects of conservation, such as the promptness of repairing leaking pipes, planning activities to conserve water, and method of car washing could be improved. Advantages and limitations of different water technologies are discussed. Sustainable water practices are also proposed.     

Comparative genotoxicity of water processed by three drinking water treatment plants with different water treatment procedures

• Genotoxicity of substances is unknown in the water after treatment processes. • Genotoxicity decreased by activated carbon treatment but increased by chlorination. • Halogenated hydrocarbons and aromatic compounds contribute to genotoxicity. • Genotoxicity was assessed by umu test; acute and chronic toxicity by ECOSAR. • Inconsistent results confirmed that genotoxicity cannot be assessed by ECOSAR. Advanced water treatment is commonly used to remove micropollutants such as pesticides, endocrine disrupting chemicals, and disinfection byproducts in modern drinking water treatment plants. However, little attention has been paid to the changes in the genotoxicity of substances remaining in the water following the different water treatment processes. In this study, samples were collected from three drinking water treatment plants with different treatment processes. The treated water from each process was analyzed and compared for genotoxicity and the formation of organic compounds. The genotoxicity was evaluated by an umu test, and the acute and chronic toxicity was analyzed through Ecological Structure- Activity Relationship (ECOSAR). The results of the umu test indicated that biological activated carbon reduced the genotoxicity by 38%, 77%, and 46% in the three drinking water treatment plants, respectively, while chlorination increased the genotoxicity. Gas chromatograph-mass spectrometry analysis revealed that halogenated hydrocarbons and aromatic compounds were major contributors to genotoxicity. The results of ECOSAR were not consistent with those of the umu test. Therefore, we conclude that genotoxicity cannot be determined using ECOSAR .     

Factors influencing the photodegradation of N-nitrosodimethylamine in drinking water

In order to provide basic data for practical application, photodegradation experiment of N-nitrosodimethylamine (NDMA) in aqueous solution was carried out with a low-pressure Hg lamp. Effects of the initial concentration of NDMA, solution pH, dissolved oxygen, and the presence of humic acid on NDMA photodegradation were investigated. NDMA at various initial concentrations selected in this study was almost completely photodegraded by UV irradiation within 20 min, except that at 1.07 mmol/L, NDMA could be photodegraded almost completely in the acidic and neutral solutions, while the removal efficiency decreased remarkably in the alkaline solution. Dissolved oxygen enhanced the NDMA photodegradation, and the presence of humic acid inhibited the degradation of NDMA. Depending on the initial concentration of NDMA, NDMA photodegradation by UV obeyed the pseudo-first-order kinetics. Dimethylamine, nitrite, and nitrate were detected as the photodegradation products of NDMA. ¹O₂ was found to be the reactive oxygen species present in the NDMA photodegradation process by UV, based on the inhibiting experiments using tert-butanol and sodium azide.     

Health importance of arsenic in drinking water and food

Arsenic is a toxic metalloid of global concern. It usually originates geogenically but can be intensified by human activities such as applications of pesticides and wood preservatives, mining and smelting operations, and coal combustion. Arsenic-contaminated food is a widespread problem worldwide. Data derived from population-based studies, clinical case series, and case reports relating to ingestion of inorganic arsenic in drinking water, medications, or contaminated food or beverages show the capacity of arsenate and arsenite to adversely affect multiple organ systems. Chronic arsenic poisoning can cause serious health effects including cancers, melanosis (hyperpigmentation or dark spots, and hypopigmentation or white spots), hyperkeratosis (hardened skin), restrictive lung disease, peripheral vascular disease (blackfoot disease), gangrene, diabetes mellitus, hypertension, and ischemic heart disease.     

Turnover mechanisms of organic conformation on turbidity in drinking water

The turbidity variation in artificial water and samples from a water plant was investigated in the presence of organics with different relative molecular mass. The results show that recessive turbidity existed when water chemical conditions were changing. The formation of turbidity depended on organic relative molecular mass and their conformations on particles. At higher pH and lower ionic strength, the organic chains with a more extended conformation resulted in rising turbidity of the suspension. At lower pH, the reconformation of organics took place due to charge neutralization by the proton, resulting in a decline in turbidity. The addition of NaCl and MgCl₂ at pH 7.00 also resulted in a decrease of turbidity in the suspension. It is believed that the occurrence of recessive turbidity has a significant influence on the stability of water supply quality.     

Health effects of arsenic in drinking water: Research needs

Research needed to resolve the uncertainties of cancer risk from ingestion of arsenic in drinking water is described. The recommendations fall into two categories reflecting the areas of greatest uncertainty regarding the assessment of arsenic risk: research on the mechanism of cancer, and research on the metabolism and detoxification of arsenic. The recommendations are discussed in light of risk assessment and risk management issues, stressing the need for scientists to interpret research findings for decision managers.This document has been reviewed in accordance with the US Environmental Protection Agency Policy and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendations for use.     

Radioactivity in drinking water: Expert opinion and policy choices

To examine the preferences of experts to selected economic and policy options in ground-water protection, we conducted an exploratory survey. We presented a group of 120 experts with an analysis of the problem of radium in drinking water supplies of Iowa, and requested their response to a variety of formal questions pertaining to specific issues related to the presence of radium in drinking water. Ninety-seven of the 120 responded. We observed definite preferences in responses to certain aspects of the problem, although in some cases their responses differed significantly due to such factors as length of ground-water related professional experience and residential status. When the presence of excessive radium in drinking water is identified, the respondents preferred immediate action in a world of incomplete knowledge over extensive future research; were willing to undertake personal action to seek radium-free water rather than wait for official action; and favoured local and state government involvement over federal intervention. Findings based on such exploratory surveys can be of much value in defining insightful research hypotheses for field testing. Confirmatory testing of such hypotheses to establish actual preferences in communities with excessive radium in drinking water is a valuable area for further research.     

Surface-enhanced Raman spectroscopy for emerging contaminant analysis in drinking water

● Definition of emerging contaminants in drinking water is introduced. ● SERS and standard methods for emerging contaminant analysis are compared. ● Enhancement factor and accessibility of SERS hot spots are equally important. ● SERS sensors should be tailored according to emerging contaminant properties. ● Challenges to meet drinking water regulatory guidelines are discussed. Emerging contaminants (ECs) in drinking water pose threats to public health due to their environmental prevalence and potential toxicity. The occurrence of ECs in our drinking water supplies depends on their physicochemical properties, discharging rate, and susceptibility to removal by water treatment processes. Uncertain health effects of long-term exposure to ECs justify their regular monitoring in drinking water supplies. In this review article, we will summarize the current status and future opportunities of surface-enhanced Raman spectroscopy (SERS) for EC analysis in drinking water. Working principles of SERS are first introduced and a comparison of SERS and liquid chromatography-tandem mass spectrometry in terms of cost, time, sensitivity, and availability is made. Subsequently, we discuss the strategies for designing effective SERS sensors for EC analysis based on five categories—per- and polyfluoroalkyl substances, novel pesticides, pharmaceuticals, endocrine-disrupting chemicals, and microplastics. In addition to maximizing the intrinsic enhancement factors of SERS substrates, strategies to improve hot spot accessibilities to the targeting ECs are equally important. This is a review article focusing on SERS analysis of ECs in drinking water. The discussions are not only guided by numerous endeavors to advance SERS technology but also by the drinking water regulatory policy.     

Pollution magnet: nano-magnetite for arsenic removal from drinking water

Arsenic contamination in groundwater is a severe global problem, most notably in Southeast Asia where millions suffer from acute and chronic arsenic poisoning. Removing arsenic from groundwater in impoverished rural or urban areas without electricity and with no manufacturing infrastructure remains a significant challenge. Magnetite nanocrystals have proven to be useful in arsenic remediation and could feasibly be synthesized by a thermal decomposition method that employs refluxing of FeOOH and oleic acid in 1-octadecene in a laboratory setup. To reduce the initial cost of production, $US 2600/kg, and make this nanomaterial widely available, we suggest that inexpensive and accessible “everyday” chemicals be used. Here we show that it is possible to create functional and high-quality nanocrystals using methods appropriate for manufacturing in diverse and minimal infrastructure, even those without electricity. We suggest that the transfer of this knowledge is best achieved using an open source concept.     

Fluoride in drinking water: A survey of expert opinions

In recent years, public debate over the standard setting process related to fluoride in drinking water and the fiuoridation of water supplies has been steeped in much controversy. Discussion of such issues has been con strained by the limited consideration of options relevant to particular problems. To examine the responses to specific issues, we presented an analysis of the problem of excessive fluoride in drinking water to a group of 120 experts. Ninety-seven of the 120 responded to a detailed mail questionnaire distributed as part of a larger exploratory survey. Definite patterns in preferences were noted with certain aspects of the problem, although in some cases significant differences were found due to such factors as the institutional affiliation, residential status, and the length of professional experience of the participants. In general, our experts preferred immediate corrective action over extensive further research into the reduction of scientific uncertainties; were willing to take personal action to obtain fluoride-free water rather than wait for official action; preferred the supplier to fluoridate the supplies, if needed; and favoured a strong local control of such issues with consumers of public water systems and private well owners shouldering much of the financial responsibility. Preliminary results from such exploratory surveys can lead to insightful research hypotheses for further testing. Verification of such hypotheses by consumers, from areas with excessive fluoride in drinking water, is a valuable area for future research.