Disinfection Byproducts and Their Precursors in Drinking Water Sources:Origins,Influencing Factors,and Environmental Insights

Tracing the contamination origins in water sources and identifying the impacts of natural and human processes are essential for ecological safety and public health.However,current analysis approaches are not ideal,as they tend to be laborious,time-consuming,or technically difficult.Disinfection byproducts(DBPs)are a family of well-known secondary pollutants formed by the reactions of chemical disinfectants with DBP precursors during water disinfection treatment.Since DBP precursors have various origins(e.g.,natural,domestic,industrial,and agricultural sources),and since the formation of DBPs from different precursors in the presence of specific disinfectants is distinctive,we argue that DBPs and DBP precursors can serve as alternative indicators to assess the contamination in water sources and identify pollution origins.After providing a retrospective of the origins of DBPs and DBP precursors,as well as the specific formation patterns of DBPs from different precursors,this article presents an overview of the impacts of various natural and anthropogenic factors on DBPs and DBP precursors in drinking water sources.In practice,the DBPs(i.e.,their concentration and speciation)originally present in source water and the DBP precursors determined using DBP formation potential tests—in which water samples are dosed with a stoichiometric excess of specific disinfectants in order to maximize DBP formation under certain reaction conditions—can be considered as alternative metrics.When jointly used with other water quality parameters(e.g.,dissolved organic carbon,dissolved organic nitrogen,fluorescence,and molecular weight distribution)and specific contaminants of emerging concern(e.g.,certain pharmaceuticals and personal care products),DBPs and DBP precursors in drinking water sources can provide a more comprehensive picture of water pollution for better managing water resources and ensuring human health.

Legislation on protection of drinking water sources and local management practices in the Pearl River Delta region of China

The protection of drinking water sources is vital to urban development and public health.In this study,the current situation of the mandatory protection area for drinking water source in the Pearl River Delta region was investigated using a method combining Google Earth with the field survey.The gaps between management practices and legislation requirements were analyzed.Finally,several countermeasures for water resource protection were proposed as follows:to promote delineation in a more scientific way,to safeguard the sanctity of the law,to make better plan on water saving,and to encourage public participation in supervision and management.

Genotoxicity evaluation and a primary risk assessment of organic pollutants in the drinking water sources of Nanjing, China

An increasing number of industrial, agricultural, and commercial chemicals in the aquatic environment leads to various deleterious effects on organisms, which is becoming an increasingly serious problem in China. In this study, the comet assay was conducted to investigate the genotoxicity to human body caused by organic concentrates in the drinking water sources of Nanjing City from Yangtze River of China, and health and ecology risk due to expose to these organic pollutants were evaluated with the multimedia environmental assessment system （MEAS）. For all the water samples, they were collected from four different locations in the drinking water sourcr samples, es of Nanjing City. The results of the comet assay showed that all the organic concentrates from the water samples could induce different levels DNA damages on human peripheral blood lymphocytes, and a statistically significant difference （p〈0.01） was observed compared with the solvent control, which demonstrated the genotoxicity was in existence. According to the ambient severity （AS） of individual compound, we had sorted out the main organic pollutants in the drinking water source of the four waterworks, and the results showed that there was some potential hazard to human body for all the source water, namely the total ambient severity （TAS） of health for each water source was more than 1. However, the TAS of ecology for each water source was less than 1, which indicated that it was safe to ecology. The results of this investigation demonstrate the application of the comet assay and the MEAS in aquatic environmental monitoring studies, and the comet assay found to be fast, sensitive, and suitable for genotoxicity monitoring programs of drinking water source.

Genotoxicity evaluation of drinking water sources in human peripheral blood lymphocytes using the comet assay

The potential harm of organic pollutants in drinking water to human health is widely focused on in the wodd; more and more pollutants with genotoxic substances are released into the aquatic environment. Water source samples were collected from 7 different localities of Nanjing City. The potential genotoxicity of organic extracts from drinking water sources were investigated by means of the comet assay in human peripheral lymphocytes. The results showed that all the organic extracts from all the water source samples could induce DNA damages of human peripheral blood lymphocytes at different levels. A significant difference （P 〈 0.01） was observed when compared with the solvent control, The DNA damage increased with the increase of the dosage of the original water source. Significant differences of DNA damage were observed in different drinking water sources, as shown by the multiple comparisons analysis at the dosage of 100x; the degree of DNA damage treated by Hushu waterworks （at town level） was the most serious, the arbitrary units （AU） was 141.62±6.96, however, that of Shangyuanmen waterworks （at city level） was only 109.64±2.97. The analysis also revealed that the genotoxicity of town＇s water sources was higher than that of the city. The results demonstrated that the comet assay can be successfully applied to the genotoxicity monitoring programs of drinking water sources.

Double-endpoint Genotoxicity Quantification and PAHs Characterization of Drinking Water Source alongside Polluted Yinghe River with High Tumor Mortality

The etiology for the high tumor mortality in heavy polluted Yinghe river basin is still unclear and polycyclic aromatic hydrocarbons(PAHs)belong to the priority pollutants in water based on the former surveillance data.In order to explore the potential genotoxicants contributing to the double-endpoint genotoxicity of polluted drinking water source,12 groundwater and 3 surface water samples were collected from 3 villages and the nearby rivers alongside Yinghe river basin,respectively and their comprehensive genotoxicity was estimated with a bioassay group of sOS/umu test and micronucleus(MN)test(MNT).Some groundwater samples showed positive genotoxicity and all surface water samples were highly genotoxic.Eight groundwater samples showed DNA genotoxic effct with the average 4-NQO equivalent concentration(TEQ_(4-NQO))of 0.067μg/L and 0.089μg/L in wet and dry season,respectively.The average MN ratios of groundwater samples were 14.19‰ and 17.52‰ in wet and dry season,respectively.Groundwater samples showed different genotoxic effect among 3 villages.The total PAHs concentrations in all water samples ranged from 8.98 to 25.17 ng/L with an average of 14.97±4.85 ng/L.BaA,CHR,BkF,BaP and DBA were the main carcinogenic PAHs contributing to the genotoxicity of water samples.In conclusion,carcinogenic PAHs are possibly related to the high tumor mortality in the target area.Characterization of carcinogenic PAHs to genotoxicity of drinking water source may shed light on the etiology study for high tumor mortality in Yinghe river basin.Key words:genotoxicity test;drinking water source;high tumor mortality;Yinghe river basin;polycyclic aromatic hydrocarbons(PAHs)

Form Distribution Characteristics of Nitrogen in a Reservoir as Drinking Water Source

Based on field detected water quality data, the distribution characteristics of different forms of nitrogen in a reservoir as drinking water source in Dongguan, which locates at the Pearl River Delta of China, have been analyzed in order to provide theoretical bases for prevention and reduction of eutrophication. The analyzed results show that nitrogen forms in the influent area of the reservoir are given priority to ammonia nitrogen and nitrate nitrogen, whose proportion is more than 45% respectively, and this is probably caused by the pollution of inflow water quality;but in the effluent area, the forms are given priority to nitrate nitrogen, whose proportion is as high as 96% and above;also the proportion of ammonia nitrogen drops by more than 80% during the process from the influent area to the effluent area, and this shows that the natural process of nitrification and denitrification can be well accomplished in the reservoir. We recommend here that to reduce the input amount of ammonia nitrogen and organic nitrogen into the reservoir is the most efficient way to prevent or mitigate eutrophication of water body.

Improving the ecological compensation mechanism for drinking water source in Yunnan province

Ecological compensation mechanism for drinking water source is one of the effective economic ways to solve the issues of the shortage of the protection investment and the lack of the driving forces to protect the water quality.The successful cases of compensation mechanism for drinking water source have examined the dilemma of improving the trans-administrative boundary compensation mechanism both in China and Yunnan.The lack of the provincial rules and regulations in Yunnan is the fundamental reason for the local government not willingly to establish the compensation mechanism.On the other hand,the shortage of the compensation funds is the key difficulty for the shareholders to reach an agreement.Formulating the rules and regulations about the construction of the compensation mechanism of drinking water source in Yunnan would be a feasible way to stipulate the local government to set up the compensation mechanism.Meanwhile,designing a complete set of compensation mechanism would make full use of the mechanism to work well to protect the water quality in an economic way.

Ammonia pollution characteristics of centralized drinking water sources in China

The characteristics of ammonia in drinking water sources in China were evaluated during 2005-2009. The spatial distribution and seasonal changes of ammonia in different types of drinking water sources of 22 provinces, 5 autonomous regions and 4 municipalities were investigated. The levels of ammonia in drinking water sources follow the order of fiver 〉 lake/reservoir 〉 groundwater. The levels of ammonia concentration in river sources gradually decreased from 2005 to 2008, while no obvious change was observed in the lakes/reservoirs and groundwater drinking water sources. The proportion of the type of drinking water sources is different in different regions. In river drinking water sources, the ammonia level was varied in different regions and changed seasonally. The highest value and wide range of annual ammonia was found in South East region, while the lowest value was found in Southwest region. In lake/reservoir drinking water sources, the ammonia levels were not varied obviously in different regions. In underground drinking water sources, the ammonia levels were varied obviously in different regions due to the geological permeability and the natural features of regions. In the drinking water sources with higher ammonia levels, there are enterprises and wastewater drainages in the protected areas of the drinking water sources.

Embedded reservoir and constructed wetland for drinking water source protection:Effects on nutrient removal and phytoplankton succession

An embedded reservoir that provides an efficient nutrient removal system protects drinking water.However,embedded reservoirs are rarely used in eutrophic shallow lakes because of their undetermined nutrient retention efficiency and unknown effects by the phytoplankton community.In this study,we aim to investigate the nutrient retention and algae succession in an embedded reservoir and adjacent wetland from April 2017 to September 2018 in the eastern part of Lake Taihu,China.More than 40%of total phosphorus(TP)and 45%of particulate phosphorous entering the reservoir were retained semiannually,and the highest TP removal efficiency was achieved in the reservoir during autumn with an average value of 53.3%±9.9%.The overall nitrogen retention efficiency(21.7%±37.8%)was lower than that of TP(41.8%±27.8%).Similar trends were obtained in the wetland area.An important pathway for phosphorus removal is through particulate matter retention.Our study revealed that nutrient retention mechanisms in the reservoir were primarily via macrophyte absorption,particulate substance sedimentation,and prolonged water residence time.Consequently,the phytoplankton biomass(Chl-a)in the reservoir decreased(from 48.0 to 25.2μg/L)and water transparency improved,due to the decreased P level and transformation of the phytoplankton group into simple structures with good ecological status.Therefore,the combination of embedded reservoir and constructed wetland ecosystem can be used successfully to protect surface water.The results will be advantageous to groups seeking to preserve drinking water sources.

Acute toxicity assessment of drinking water source with luminescent bacteria: Impact of environmental conditions and a case study in Luoma Lake, East China

Protecting the quality of lake watersheds by preventing and reducing their contamination is an effective approach to ensure the sustainability of the drinking water supply.In this study,acute toxicity assessment was conducted on the basis of acute bioluminescence inhibition assay using the marine bacterium Vibrio fischeri as the test organism and Luoma Lake drinking water source in East China as the research target.The suitable ranges of environmental factors,including pH value,organic matter,turbidity,hardness,and dissolved oxygen of water samples were evaluated for the toxicity testing of bioluminescent bacteria.The physicochemical characteristics of water samples at the selected 43 sites of Luoma Lake watershed were measured.Results showed that the variations in pH value(7.31-8.41),hardness(5-20°d)and dissolved oxygen(4.44-11.03 mg/L)of Luoma Lake and its main inflow and outflow rivers had negligible impacts on the acute toxicity testing of V.fischeri.The luminescence inhibition rates ranged from-11.21%to 10.80%at the 43 sites.Pearson's correlation analysis in the experiment revealed that temperature,pH value,hardness,and turbidity had no correlation with luminescence inhibition rate,whereas dissolved oxygen showed a weak statistically positive correlation with a Pearson correlation coefficient of 0.455(p<0.05).

Riparian habitat quality as an indicator of land use/land cover effects on riverine water quality

Riparian land use/land cover(LULC)plays a crucial role in maintaining riverine water quality by altering the transport of pollutants and nutrients.Nevertheless,establishing a direct relationship between water quality and LULC is challenging due to the multi-indicator nature of both factors.Water quality encompasses a multitude of physical,chemical,and biological parameters,while LULC represents a diverse array of land use types.Riparian habitat quality(RHQ)serves as an indicator of LULC.Yet,it remains to be seen whether RHQ can act as a proxy of LULC for assessing the impact of LULC on riverine water quality.This study examines the interplay between RHQ,LULC and water quality,and develops a comprehensive indicator to predict water quality.We measured several water quality parameters,including pH(potential of hydrogen),TN(total nitrogen),TP(total phosphorus),T_(water)(water temperature),DO(dissolved oxygen),and EC(electrical conductivity)of the Yue and Jinshui Rivers draining to the Han River during 2016,2017 and 2018.The water quality index(WQI)was further calculated.RHQ is assessed by the InVEST(Integrated Valuation of Ecosystem Services and Tradeoffs)model.Our study found noticeable seasonal differences in water quality,with a higher WQI observed in the dry season.The RHQ was strongly correlated with LULC compositions.RHQ positively correlated with WQI,and DO concentration and vegetation land were negatively correlated with T_(water),TN,TP,EC,cropland,and construction land.These correlations were stronger in the rainy season.Human-dominated land,such as construction land and cropland,significantly contributed to water quality degradation,whereas vegetation promoted water quality.Regression models showed that the RHQ explained variations in WQI better than LULC types.Our study concludes that RHQ is a new and comprehensive indicator for predicting the dynamics of riverine water quality.

Designing principles of an ecological water storage basin on coastal saline: a case study

The degradation of water source environment becomes serious problems accompanying with rapid urbanization in China. Ecological engineering provides ecologically sound and cost effective solution to solving this problem. As a case study, a 15 hm 2 ecological water storage basin for a water plant was designed and constructed on the TEDA area in Tianjin City. Located on saline, the construction of this project has to face serious difficulties, such as high salinity, scarce seed banks of macrophytes, and strong winds. Freshwater replacement, soil amendation and macrophytes planting at the basinshore, wooden water breaker and plastic membrane installation and other measures were conducted for the assistance of plant community establishment. The result showed that the chloride concentration in the basin water decreased from 11600 mg/L to less than 100 mg/L, and the chloride content in the basin sediment decreased from 2 1% to 0 35% after freshwater soaking. The introduced macrophytes of 8 species all survived and 11 other macrophytes species were occurred in the basin. A new ecosystem was created with increased biological diversity in the original saline, and the water quality was improved. This ecological water storage basin also provided a pleasing landscape for local people.

Importance and vulnerability of lakes and reservoirs supporting drinking water in China

Drinking water is closely related to human health,disease and mortality,and contaminated drinking water causes 485,000 deaths from diarrhea each year worldwide.China has been facing increasingly severe water scarcity due to both water shortages and poor water quality.Ensuring safe and clean drinking water is a great challenge and top priority,especially for China with 1.4 billion people.In China,more than 4000 centralized drinking water sources including rivers,lakes and reservoirs,and groundwater have been established to serve urban residents.However,there is little knowledge on the percentage,serving population and water quality of three centralized drinking water source types.We collected nationwide centralized drinking water sources data and serving population data covering 395 prefecture-level and county-level cities and water quality data in the two most populous provinces(Guangdong and Shandong)to examine their contribution and importance.Geographically,the drinking water source types can be classified into three clear regions exhibiting apparent differences in the respective contributions of rivers,lakes and reservoirs,and groundwater.We further found that overall,lakes and reservoirs account for 40.6%of the centralized drinking water sources vs.river(30.8%)and groundwater(28.6%)in China.Lakes and reservoirs are particularly important in the densely populated eastern region,where they are used as drinking water sources by 51.0%of the population(318 million).Moreover,the contribution to the drinking water supply from lakes and reservoirs is increasing due to their better water quality and many cross-regional water transfer projects.These results will be useful for the government to improve and optimize the establishment of centralized drinking water sources,which provide safe and clean drinking water in China to safeguard people's lives and health and realize sustainable development goals.

Eco-environmental vulnerability assessment for large drinking water resource： a case study of Qiandao Lake Area, China

The Qiandao Lake Area （QLA） is of great significance in terms of drinking water supply in East Coast China as well as a nationally renowned tourist attraction. A series of laws and regulations regarding the QLA environment have been enacted and implemented throughout the past decade with the aim of negating the harmful effects associated with expanding urbanization and industrialization. In this research, an assessment framework was developed to analyze the eco-environ- mental vulnerability of the QLA from 1990-2010 by integrating fuzzy analytic hierarchy process （FAHP） and geographical information systems （GIS） in an attempt to gain insights into the status quo of the QLA so as to review and evaluate the effectiveness of the related policies. After processing and analyzing the temporal and spatial variation of eco-environmental vulnerability and major environ- mental issues in the QLA, we found that the state of eco- environmental vulnerability of the QLA was acceptable, though a moderate deterioration was detected during the study period. Furthermore, analysis of the combination of vulnerability and water quality indicated that the water quality showed signs of declination, though the overall status remained satisfactory. It was hence concluded that the collective protection and treatment actions were effective over the study period, whereas immediately stricter measures would be required for protecting the drinking water quality from domestic sewage and industrial wastewater. Finally, the spatial variation of the eco-environmental vulnerability assessment also implied that specifically more targeted measures should be adoptedin respective regions for long-term sustainable develop- ment of the QLA.

Water quality monitoring in a slightly-polluted inland water body through remote sensing-Case study of the Guanting Reservoir in Beijing,China

This study focused on the water quality of the Guanting Reservoir,a possible auxiliary drinking water source for Beijing.Through a remote sensing(RS)approach and using Landsat 5 Thematic Mapper(TM)data,water quality retrieval models were established and analyzed for eight common water quality variables,including algae content,turbidity,and concentrations of chemical oxygen demand,total nitrogen,ammonia nitrogen,nitrate nitrogen,total phosphorus,and dissolved phosphorus.The results show that there exists a statistically significant correlation between each water quality variable and remote sensing data in a slightly-polluted inland water body with fairly weak spectral radiation.With an appropriate method of sampling pixel digital numbers and multiple regression algorithms,retrieval of the algae content,turbidity,and nitrate nitrogen concentration was achieved within 10% mean relative error,concentrations of total nitrogen and dissolved phosphorus within 20%,and concentrations of ammonia nitrogen and total phosphorus within 30%.On the other hand,no effective retrieval method for chemical oxygen demand was found.These accuracies were acceptable for the practical application of routine monitoring and early warning on water quality safety with the support of precise traditional monitoring.The results show that performing the most traditional routine monitoring of water quality by RS in relatively clean inland water bodies is possible and effective.