Spatial distribution of drinking and irrigation water quality indices of Ghizer River Basin,northern Pakistan

Environmental Science and Pollution Research - Determining the water contamination of a river that threatens the dependent ecological community is a pillar for sustainable management. For this...     

Nano-silver in drinking water and drinking water sources: stability and influences on disinfection by-product formation

Nano-silver is increasingly used in consumer products from washing machines and refrigerators to devices marketed for the disinfection of drinking water or recreational water. The nano-silver in these products may be released, ending up in surface water bodies which may be used as drinking water sources. Little information is available about the stability of the nano-silver in sources of drinking water, its fate during drinking water disinfection processes, and its interaction with disinfection agents and disinfection by-products (DBPs). This study aims to investigate the stability of nano-silver in drinking water sources and in the finished drinking water when chlorine and chloramines are used for disinfection and to observe changes in the composition of DBPs formed when nano-silver is present in the source water. A dispersion of nano-silver particles (10 nm; PVP-coated) was used to spike untreated Ottawa River water, treated Ottawa River water, organic-free water, and a groundwater at concentrations of 5 mg/L. The diluted dispersions were kept under stirred and non-stirred conditions for up to 9 months and analyzed weekly using UV absorption to assess the stability of the nano-silver particles. In a separate experiment, Ottawa River water containing nano-silver particles (at 0.1 and 1 mg/L concentration, respectively) was disinfected by adding sodium hypochlorite (a chlorinating agent) in sufficient amounts to maintain a free chlorine residual of approximately 0.4 mg/L after 24 h. The disinfected drinking water was then quenched with ascorbic acid and analyzed for 34 neutral DBPs (trihalomethanes, haloacetonitriles, haloacetaldehydes, 1,1 dichloro-2-propanone, 1,1,1 trichloro-2-propanone, chloropicrin, and cyanogen chloride). The results were compared to the profile of DBPs obtained under the same conditions in the absence of nano-silver and in the presence of an equivalent concentration of Ag⁺ ions (as AgNO₃). The stability of the nano-silver dispersions in untreated Ottawa River water, with a dissolved organic carbon concentration of 6 mg/L, was significantly higher than the stability of the nano-silver dispersions in distilled, organic-free water. Nano-silver particles suspended in the groundwater agglomerated and were quickly and quantitatively removed from the solution. Our data confirm previous observations that natural dissolved organic matter stabilizes nano-silver particles, while the high-ionic strength of groundwater appears to favor their agglomeration and precipitation. As expected, nano-silver was not stable in Ottawa River water through the chlorination process, but survived for many days when added to the Ottawa River water after treatment with chlorine or chloramines. Stirring appeared to have minimal effect on nano-silver stability in untreated and treated Ottawa River water. The profile of DBPs formed in the presence of nAg differed significantly from the profile of DBPs formed in the absence of nAg only at the 1 mg/L nAg concentration. The differences observed consisted mainly in reduced formation of some brominated DBPs and a small increase in the formation of cyanogen chloride. The reduced formation of brominated congeners may be explained by the decrease in available bromide due to the presence of Ag⁺ ions. It should be noted that a concentration of 1 mg/L is significantly higher than nAg concentrations that would be expected to be present in surface waters, but these results could be significant for the disinfection of some wastewaters with comparably high nano-silver concentrations.     

Predictive model for disinfection by-product in Alexandria drinking water, northern west of Egypt

Chlorine has been utilized in the early stages of water treatment processes as disinfectant. Disinfection for drinking water reduces the risk of pathogenic infection but may pose a chemical threat to human health due to disinfection residues and their by-products (DBP) when the organic and inorganic precursors are present in water. In the last two decades, many modeling attempts have been made to predict the occurrence of DBP in drinking water. Models have been developed based on data generated in laboratory-scale and field-scale investigations. The objective of this paper is to develop a predictive model for DBP formation in the Alexandria governorate located at the northern west of Egypt based on field-scale investigations as well as laboratory-controlled experimentations. The present study showed that the correlation coefficient between trihalomethanes (THM) predicted and THM measured was R ²?=?0.88 and the minimum deviation percentage between THM predicted and THM measured was 0.8 %, the maximum deviation percentage was 89.3 %, and the average deviation was 17.8 %, while the correlation coefficient between dichloroacetic acid (DCAA) predicted and DCAA measured was R ²?=?0.98 and the minimum deviation percentage between DCAA predicted and DCAA measured was 1.3 %, the maximum deviation percentage was 47.2 %, and the average deviation was 16.6 %. In addition, the correlation coefficient between trichloroacetic acid (TCAA) predicted and TCAA measured was R ²?=?0.98 and the minimum deviation percentage between TCAA predicted and TCAA measured was 4.9 %, the maximum deviation percentage was 43.0 %, and the average deviation was 16.0 %.     

给水管网疏松沉积物的结构特征及其风险识别

自来水变色问题通常被视为感官问题,而导致自来水变色的管网疏松沉积物的结构特征及其潜在危害尚不明确。采集了我国北方某城市频繁发生自来水“黄水”的7个小区管网中的疏松沉积物,并进行了分析。结果表明：所有疏松沉积物样品中含量最高的金属元素都是铁元素、主要晶体成分是铁氧化物,样品颗粒微观形貌大多具有锋利的针刺状结构;样品zeta电位范围为−15~20 mV、平均粒径范围为500~4 000 nm、粗糙度范围为0.25~7.81 nm。体外细胞毒性实验结果显示,沉积物可产生一定的细胞毒性(样品浓度100 mg·L⁻¹时人体健康肝脏细胞存活率为86.61%~99.71%)。通过主成分分析发现,疏松沉积物毒性与粗糙度的相关性比与粒度的高,表明形貌对样品毒性的影响比粒径更大;γ-FeOOH是与疏松沉积物毒性相关性最显著的晶体组分,其对毒性的贡献可能是通过增加颗粒表面锋利程度造成的,余氯不足时可能会因铁释放加剧和γ-FeOOH含量增大造成更高的毒性风险。本研究结果可为全面认识给水管网疏松沉积物的风险提供参考。     

Eukaryotic diversity in premise drinking water using 18S rDNA sequencing: implications for health risks

The goal of this study was to characterize microbial eukaryotes over a 12-month period to provide insight into the occurrence of potential bacterial predators and hosts in premise plumbing. Nearly 6,300 partial 18S rRNA gene sequences from 24 hot (36.9–39.0 °C) and cold (6.8–29.1 °C) drinking water samples were analyzed and classified into major eukaryotic groups. Each major group, consisting of free-living amoebae (FLA)/protozoa, algae, copepods, dinoflagellates, fungi, nematodes, and unique uncultured eukaryotic sequences, showed limited diversity dominated by a few distinct populations, which may be characteristic of oligotrophic environments. Changes in the relative abundance of predators such as nematodes, copepods, and FLA appear to be related to temperature and seasonal changes in water quality. Sequences nearly identical to FLA such as Hartmannella vermiformis, Echinamoeba thermarmum, Pseudoparamoeba pagei, Protacanthamoeba bohemica, Platyamoeba sp., and Vannella sp. were obtained. In addition to FLA, various copepods, rotifers, and nematodes have been reported to internalize viral and bacterial pathogens within drinking water systems thus potentially serving as transport hosts; implications of which are discussed further. Increasing the knowledge of eukaryotic occurrence and their relationship with potential pathogens should aid in assessing microbial risk associated with various eukaryotic organisms in drinking water.     

Interpreting drinking water quality in the distribution system using Dempster-Shafer theory of evidence

Interpreting water quality data routinely generated for control and monitoring purposes in water distribution systems is a complicated task for utility managers. In fact, data for diverse water quality indicators (physico-chemical and microbiological) are generated at different times and at different locations in the distribution system. To simplify and improve the understanding and the interpretation of water quality, methodologies for aggregation and fusion of data must be developed. In this paper, the Dempster-Shafer theory also called theory of evidence is introduced as a potential methodology for interpreting water quality data. The conceptual basis of this methodology and the process for its implementation are presented by two applications. The first application deals with the interpretation of spatial water quality data fusion, while the second application deals with the development of water quality index based on key monitored indicators. Based on the obtained results, the authors discuss the potential contribution of theory of evidence as a decision-making tool for water quality management.     

Site-specific water quality guidelines: 2. Development of a water quality regulation framework for pulse exposures of mine water discharges at a uranium mine in northern Australia

The Ranger Uranium Mine, in northern Australia, is monitored by the Supervising Scientist Division (SSD) of the Australian Government to ensure that it does not impact on the highly valued aquatic ecosystems of Kakadu National Park. In 2010, the SSD adopted the continuous monitoring of electrical conductivity (EC) and turbidity, in combination with event-triggered automated grab samples, as its primary water quality monitoring method. The continuous monitoring of EC has shown that mine discharges typically occur over short-term ‘pulse’ durations of minutes to hours. Given that magnesium (Mg) is the most likely mine-derived solute to approach or exceed the applicable water quality limit value, the focus has been on developing a pulse exposure assessment framework for Mg, as represented by its proxy EC, which is tracked by the continuous monitoring system. This study presents a possible ecotoxicologically derived Mg pulse exposure limit and trigger regulation framework for Magela and Gulungul Creeks and an assessment of historic continuous monitoring EC data from these creeks. This framework demonstrates potential to supersede the current EC guideline and associated trigger levels, which are statistically derived from historic grab sample data.     

基于不同水厂水质调查的消毒副产物生成趋势及模型预测

以南方某市具有代表性的7个自来水厂为研究对象,对不同季节和不同处理工艺下的原水、出厂水和管网水的9个常规水质参数和2类含碳消毒副产物进行了检测,考察了水质指标随季节的变化规律和处理工艺对不同水质指标的影响,分析了常规水质参数与消毒副产物生成量之间的关系。结果表明：7个自来水厂出厂水均检出三卤甲烷(trihalomethanes,THMs)和卤乙酸(haloacetic acids,HAAs);THMs平均质量浓度为8.70~29.35 μg·L⁻¹,HAAs平均质量浓度为13.22~39.06 μg·L⁻¹;管网水中2类消毒副产物浓度水平较出厂水略有增加;THMs的季节变化规律为冬季>春季≈秋季>夏季,HAAs的季节变化性不强。利用IBM SPSS Statistics 20进行了Spearman秩相关系数分析,并分别以原水和出厂水水质参数来建立出厂水THMs或HAAs生成量的回归方程。结果表明：THMs质量浓度预测效果良好,可用于自来水厂水质的化学安全性预警;但对于HAAs质量浓度预测,无论采用原水还是出厂水水质参数所建立的预测方程,预测结果均不理想。     

Multi-route human health risk assessment from trihalomethanes in drinking and non-drinking water in Abadan,Iran

Natural organic matter reacted with chlorine used for disinfection, and finally, trihalomethanes (THMs) are formatted. The main purpose of this study was to determine four THM concentrations and human health cancer risk and non-cancer risk assessment from exposure through oral ingestion, dermal contact, and inhalation for males and females in Abadan. Two sampling sites were selected, and five samples before and after treatment by two different water treatment systems (RO and ion exchange) were collected every week. Results showed that total THM concentrations before and after treatment by RO were 98.1 and 8.88 μg/L, and ion exchange ranged between 101.9 and 14.96 μg/L, respectively, that before treatment was upper than the maximum of 80 mg/L recommended by USEPA. Inhalation was the primary route of exposure by around 80–90% of cancer risk. Total cancer risk was higher than the USEPA acceptable limit of 10^?6 via three exposure routes. Oral route has the higher hazard index values than dermal ways.

     

岛屿环境下水泥屋顶和水泥路面雨水径流水质特性及其用作饮用水的可行性

以岛屿典型集水面(水泥路面和水泥屋顶)的雨水径流为研究对象,系统分析了雨季和旱季雨水径流的水质历时变化特征,并对岛屿收集雨水用作饮用水的可行性进行了分析。结果表明：雨季由于降雨强度大且降雨集中,水质明显好于旱季;屋顶受环境及人为因素干扰小,水质好于路面。建议收集雨水顺序为雨季屋顶>旱季屋顶>雨季路面,旱季路面水质较差,不建议收集。岛屿不同环境下收集的雨水水质分析结果表明,超出生活饮用水卫生标准的指标主要有色度、浊度、少量金属(铝和铅)、氨氮、有机物和微生物等,且超标指标在降雨初期随降雨时间的增加而迅速降低,之后逐渐趋于稳定。因此,对初期雨水进行弃流可极大改善收集雨水水质。雨水径流饮用水化可行性分析结果表明,根据降雨情况和集水面性质,采取合理的弃流方案并结合过滤和消毒等净化工艺,可实现雨水饮用水化。研究结果可为降雨量丰富的岛屿及东南亚和南亚的“一带一路”沿线国家利用雨水解决饮用水问题提供借鉴。     

老旧无内衬铸铁管中氯对水质的影响

给水管网铁释放对于饮用水水质具有重要影响。通过浸泡实验和烧杯实验探究实际老旧无内衬铸铁管中氯对铁腐蚀的影响。一方面,通过实际管段浸泡实验,对比了不同初始氯浓度下管道中水质变化,发现在高初始氯下浊度和三磷酸腺苷增大,这表明在铁释放严重的无衬里铸铁管道中,消毒剂的增加可能引发水质微生物风险;另一方面,通过烧杯实验进一步确认了氯对管网颗粒物结构的影响,发现氯能够通过降低颗粒物表面电荷导致静电排斥降低,从而加剧了颗粒物的团聚,导致粒径变大、浊度升高,且颗粒物对消毒副产物三卤甲烷具有一定的富集累积作用,引发水质化学风险。本研究结果可为了解给水管网中氯引发的黄水风险提供参考。     

Water safety plans as a tool for drinking water regulatory frameworks in Arctic communities

Arctic communities often face drinking water supply challenges that are unique to their location. Consequently, conventional drinking water regulatory strategies often do not meet the needs of these communities. A literature review of Arctic jurisdictions was conducted to evaluate the current water management approaches and how these techniques could be applied to the territory of Nunavut in Canada. The countries included are all members of the Arctic Council and other Canadian jurisdictions considered important to the understanding of water management for Northern Canadian communities. The communities in Nunavut face many challenges in delivering safe water to customers due to remoteness, small community size and therefore staffing constraints, lack of guidelines and monitoring procedures specific to Nunavut, and water treatment and distribution systems that are vastly different than those used in southern communities. Water safety plans were explored as an alternative to water quality regulations as recent case studies have demonstrated the utility of this risk management tool, especially in the context of small communities. Iceland and Alberta both currently have regulated water safety plans (WSPs) and were examined to understand shortcomings and benefits if WSPs were to be applied as a possible strategy in Nunavut. Finally, this study discusses specific considerations that are necessary should a WSP approach be applied in Nunavut.     

An early warning and control system for urban, drinking water quality protection: China’s experience

An event-driven, urban, drinking water quality early warning and control system (DEWS) is proposed to cope with China’s urgent need for protecting its urban drinking water. The DEWS has a web service structure and provides users with water quality monitoring functions, water quality early warning functions, and water quality accident decision-making functions. The DEWS functionality is guided by the principles of control theory and risk assessment as applied to the feedback control of urban water supply systems. The DEWS has been deployed in several large Chinese cities and found to perform well insofar as water quality early warning and emergency decision-making is concerned. This paper describes a DEWS for urban water quality protection that has been developed in China.     

Halogenated acetaldehydes: analysis, stability and fate in drinking water

In our previous studies, chloral hydrate has been the only chlorinated acetaldehyde determined in drinking water because authentic standards of other related haloacetaldehydes were not available. Recently, standards of dichloroacetaldehyde, bromochloroacetaldehyde, dibromoacetaldehyde, bromodichloroacetaldehyde, chlorodibromoacetaldehyde, and tribromoacetaldehyde have become available commercially. They were obtained and verified for purity and stability using a dual-column GC-ECD system. Each commercial standard was found to contain small amounts of the other target haloacetaldehydes (HAs). The stability of the HAs stock solutions was solvent dependent: in acetone, the brominated species partially degraded to bromoacetone, while all target HAs were stable in MTBE for up to 8 months. The analytical parameters, required for the quantification of HAs in water, were determined and used to evaluate the stability of the HAs in water. Under the conditions of the sampling protocol (field pH adjustment to pH 4.5 and storage at 4 degrees C), the target HAs were stable in water for up to 14 days. However, at typical drinking water pH and temperature conditions, the stability varied with the HA species, pH, temperature and storage period. The trihalogenated acetaldehydes degraded, in part, to their corresponding trihalomethanes (THMs) at increasing pH and temperature. Most target HAs were detected in drinking water samples collected from various Canadian drinking water systems, and the speciation was dependent on water parameters (e.g. bromide concentration) and treatment processes. From the water samples analysed, chloral hydrate ranged between 7% and 51% of the total HAs (w/w). The weigh ratio of total HAs to total THMs (10-46%) indicated that HAs contributed significantly to the pool of DBPs in drinking water.     

Probabilistic health risk assessment of nitrosamines in drinking water of Shaoxing,Zhejiang, China

Environmental Science and Pollution Research - Nitrosamines (NAms) are potent genotoxic and carcinogenic but widely detected in drinking water. This study aimed to investigate the occurrence of...     

Decomposition of dihaloacetonitriles in water solutions and fortified drinking water samples

An investigation of the decomposition of dihaloacetonitriles (DHANs) in water solutions and fortified drinking water samples was conducted. The concentrations of dichloroacetonitrile (CHCl2CN, DCAN), bromochloroacetonitrile (CHBrClCN, BCAN) and dibromoacetonitrile (CHBr2CN, DBAN) were determined by a gas chromatography mass spectrometry (GC-MS) method at regular time intervals and different temperatures. The effect of sodium thiosulfate (Na2S2O3), which is used as a preservative in water samples, was also examined. The rates of decomposition were determined for each compound. The results show that the reactions are faster in fortified drinking water samples than in ultrapure water solutions. They are also favored at higher temperature, especially when sodium thiosulfate is present. The highest decomposition rate is shown by DCAN, followed by BCAN and DBAN, while at the presence of sodium thiosulfate the decomposition of DBAN is the fastest.     

饮用水的异嗅异味研究进展

饮用水的异嗅异味问题已日益引起人们的重视。近几年，国内外在研究饮用水异嗅异味物质产生的原因、分析和控制的方法等方面取得了一些进展。     

Temporospatial variation and health risk assessment of trihalomethanes (THMs) in drinking water (northwest Iran)

Environmental Science and Pollution Research - Trihalomethanes (THMs) are one of the most common classes of disinfection by-products. In this study, the temporospatial trends and health risks due...