Contaminant transport in a municipal drinking water supply: a steady-state approach to estimate rate and uncertainty

Contaminant transport is generally considered to be a key factor when assessing and classifying the environmental risk of polluted areas. In the study presented here, a steady-state approach was applied to obtain estimates of the transit time and concentration of the pesticide metabolite BAM (2,6-dichlorobenzoamide) at a site where it is contaminating a municipal drinking water supply. A Monte Carlo simulation technique was used to quantify the uncertainty of the results and to evaluate the sensitivity of the used parameters. The adopted approach yielded an estimated median transit time of 10 y for the BAM transport from the polluted site to the water supply. Soil organic carbon content in the unsaturated zone and the hydraulic conductivity in the saturated zone explained 44% and 23% of the uncertainty in the transit time estimate, respectively. The sensitivity analysis showed that the dilution factor due to regional groundwater flow and the soil organic carbon content at the polluted site explained 53% and 31% of the uncertainty of concentration estimates, respectively. In conclusion, the adopted steady-state approach can be used to obtain reliable first estimates of transit time and concentration, but to improve concentration predictions of degrading contaminants, a dynamic model is probably required.     

Formation of halogenated acetaldehydes, and occurrence in Canadian drinking water

Controlled laboratory chlorination of acetaldehyde (ACD) under typical drinking water conditions (pH 6.7, 7.6 and 8.8, and temperature 4 degrees C and 21 degrees C) revealed that the formation of chloral hydrate (CH), the most common halogenated acetaldehyde (HAs), increased with contact time (0-10 days). However, at increased pH and temperature, CH reached maximum levels and subsequently broke down partially to chloroform and other unidentified compounds. After 10 days contact time, a maximum of 63% (molar) of the initial ACD consumed were converted into CH or chloroform (TCM). Various surveys of drinking water systems indicated that ACD is not the only precursor of CH. A suite of aldehydes (including ACD), and chlorinated disinfection by-products (including TCM and CH) were found in most distribution systems. The levels of bromide in source water impacted speciation of HAs. In addition to CH, brominated and other mixed (Cl/Br) acetaldehydes were detected in most samples; the speciation of HAs and THMs followed comparable trends. Similar to chloroform for trihalomethanes, CH contributed from as low as 5% to up to 60% of the total HAs. The bromine incorporation factors (BIF) in THMs and HAs were shown to increase with increasing bromide ion concentrations in the source water. Brominated THMs are more readily formed than their HA analogues; in fact, BIF values for THMs were 2-3 times higher than for the HAs. It was found that HAs may be as high as THMs in some drinking waters. As a result, the determination of the other target HAs, in addition to CH, is necessary for a better assessment of the pool of disinfection by-products in drinking water.     

Wastewater treatment and public health in Nunavut: a microbial risk assessment framework for the Canadian Arctic

Wastewater management in Canadian Arctic communities is influenced by several geographical factors including climate, remoteness, population size, and local food-harvesting practices. Most communities use trucked collection services and basic treatment systems, which are capable of only low-level pathogen removal. These systems are typically reliant solely on natural environmental processes for treatment and make use of existing lagoons, wetlands, and bays. They are operated in a manner such that partially treated wastewater still containing potentially hazardous microorganisms is released into the terrestrial and aquatic environment at random times. Northern communities rely heavily on their local surroundings as a source of food, drinking water, and recreation, thus creating the possibility of human exposure to wastewater effluent. Human exposure to microbial hazards present in municipal wastewater can lead to acute gastrointestinal illness or more severe disease. Although estimating the actual disease burdens associated with wastewater exposures in Arctic communities is challenging, waterborne- and sanitation-related illness is believed to be comparatively higher than in other parts of Canada. This review offers a conceptual framework and evaluation of current knowledge to enable the first microbial risk assessment of exposure scenarios associated with food-harvesting and recreational activities in Arctic communities, where simplified wastewater systems are being operated.     

Chemical and microbiological qualities of The East River (Dongjiang) water,with particular reference to drinking water supply in Hong Kong

Currently, about 80% of drinking water in Hong Kong is abstracted from The East River (Dongjiang) that is located in the mainland side of China. Literature records and monitoring results of 2000-2001 confirmed that the lower section of the Dongjiang had been contaminated by organic and inorganic pollutants. Statistical analyses showed that the increases of total cadmium, copper and zinc in the surface layer of sediment of Hong Kong reservoirs from 1994 to 2001 were positively correlated (significant at p<0.05) with those in the surface layer of sediments of the lower Dongjiang. Recent microbiological survey revealed that pathogens such as Salmonella spp., Vibro spp., Giardia lamblia and Cryptosporidium parvum appeared occasionally in water samples of the Dongjiang and Hong Kong reservoirs. While analytical results found that currently most of the heavy metals, trace organics and microbes were removed by the drinking water treatment plants in Hong Kong, the long-term health risk of drinking water contamination should not be overlooked. The Water Supplies Department of Hong Kong is recommended to intensify its water quality monitoring program to cover pathogenic bacteria and parasites in watercourses and reservoirs.     

饮用水生物处理中微生物量和活性的测定方法

微生物量和微生物活性是饮用水生物处理工艺设计与运行的重要参数。总结论述了适用于表示饮用水生物处理过程生物膜中微生物数量和活性的几种主要指标的测定方法。     

饮用水生物处理中微生物量和活性的测定方法

微生物量和微生物活性是饮用水生物处理工艺设计与运行的重要参数。总结论述了适用于表示饮用水生物处理过程生物膜中微生物数量和活性的几种主要指标的测定方法。     

城市给水厂污泥对污水中磷的动态吸附

以城市给水厂污泥为原料,制备了2种不同粒径的颗粒状吸附剂,探讨了这2种颗粒吸附剂不同应用方式动态吸附初沉池水中磷的效果,并对吸附的影响因素进行了探究。结果表明,在使用2 mm粒径的吸附剂进行动态吸附时,在颗粒投加量固液比为20 g·L~(-1)的条件下,运行8 h后,出水磷浓度最低,总磷、可溶性总磷、可溶性活性磷酸盐的出水浓度分别可达到1.52、0.27、0.16 mg·L~(-1)。干化大颗粒的固定床吸附实验结果表明,空床停留时间应控制在30 min左右,有效滤层高度为11.5 cm,滤柱连续运行前80 h,对初沉池水有良好的处理效果,为该吸附剂投入使用提供了初步依据。对给水厂污泥颗粒吸附剂进行了技术经济分析,得出颗粒吸附剂理论上处理初沉池水所需药剂费用为0.021 2元·t~(-1),具有较高的经济效益。以上结果可为给水厂的污泥在实际生产中的应用提供参考。     

复合人工湿地对水源地库区水质净化效果分析

宁波皎口水库是水源地,皎口复合人工湿地位于皎口水库的进水口,采用多种水流方式复合,对提高水库水质及保障饮用水安全具有积极的作用。为了探明人工湿地在微污染地区的应用价值,对人工湿地水源地水质净化效能进行了研究。在1年的监测调查调查中,研究探讨了复合人工湿地及其不同模块在不同季节的净化效果。结果表明,该人工湿地对总氮和总磷的平均去除率分别可达到为34.7%和42.6%,对COD和TOC的平均去除率可达到28.5%和21.6%。COD、NH₄⁺-N和总磷出水平均浓度分别为2.193、0.215和0.021 mg/L,均达到 《地表水环境质量标准》（GB3838-2002）Ⅱ类水质标准。在比较不同模块去除效果方面,提出了具有填料的生态滤池更有利于磷的去除,而对于氮、有机物等营养元素,复合多级强化生物膜系统及营养盐集约式植物资源化系统则有较好的去除效果。     

北京市某城市污水处理厂微生物气溶胶污染特性研究

以北京市某城市污水处理厂的格栅间、曝气池、污泥浓缩池和污泥脱水间为对象,研究不同功能区的空气微生物浓度、粒径分布及微生物组成.结果表明:(1)该污水处理厂4个功能区空气异养细菌浓度平均值为3.3×104cfu/m3,范围为1.0×102～4.3×105cfu/m3;真菌浓度平均值为6.1×103cfu/m3,范围为7.5×10～7.6×104cfu/m3.异养细菌和真菌浓度存在显著性差异,尤以曝气池上空最高,其次是污泥脱水间,浓度最低的区域为格栅间和污泥浓缩池.各功能区均存在不同程度的异养细菌和真菌污染.(2)该污水处理厂不同功能区逸散出的异养细菌分布比例最高的为第2～5级,真菌主要分布在第3～5级.4个功能区空气中粒径为2.10～4.70μm(第3、4级)的异养细菌和真菌粒子分别占到了总数的37％～40％和46％～56％,而粒径为0.65～2.10μm(第5、6级)的异养细菌和真菌粒子则分别占到了总数的30％～33％和31％～37％,说明该污水处理厂不同功能区内的空气微生物存在一定的健康风险,可能对人呼吸道构成感染威胁.(3)假单孢菌(Pseudomonas)为该污水处理厂不同功能区均检出的优势异养细菌,而优势真菌种属为毛霉(Mucor)和曲霉(Aspergillus).     

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.     

A study on organotin levels in Canadian drinking water distributed through PVC pipes

A study on organotin compounds in Canadian drinking water was carried out in winter-spring 1996 (28 sites) and autumn 1996 (21 sites). Approximately 29% and 40% of distribution waters supplied through PVC pipes installed recently (typically less than 6 months) contained organotin compounds in the winter-spring and autumn surveys respectively. Monomethyl-, dimethyl-, monobutyl- and dibutyltin levels ranged up to 291 ng Sn/L, 49.1 ng Sn/L, 28.5 ng Sn/L and 52.3 ng Sn/L, respectively. An additional study in summer 1996, of locations where the highest organotin levels were detected in the winter-spring survey, indicated that organotin levels had decreased in most distribution water samples. Samples of PVC pipe/tubing contained organotin compounds consistent with the organotin patterns found in the distribution water samples.     

某水源水库嗅味来源及潜在产嗅藻分布特征解析

华东地区某水源水库近年来出现季节性嗅味问题。为解析嗅味产生来源及其成因,于2018年4月至2019年12月对该水库上游以及库内水体进行长期监测。监测结果表明,2-甲基异莰醇(2-MIB)是主要的土霉味致嗅物质,伪鱼腥藻是该水库潜在产嗅藻种,且其主要为外源输入。相关性分析结果表明,伪鱼腥藻的生长与水温及水下光照(透明度、浊度)等有关。为进一步解析水下光照因素驱动下伪鱼腥藻在水库水体中的分布特征,在水库高嗅期间开展了72 h连续监测,重点分析了伪鱼腥藻昼夜与垂向分布特征。结果表明,在08:00,伪鱼腥藻往表层迁移,在10:00—14:00,表层密度达到最高值,白天在水体中呈现明显的垂向迁移特征,而夜晚在水体中各层的分布无明显变化,这进一步说明水下光照对伪鱼腥藻生长的重要性。以上结果进一步提升了对实际水体中伪鱼腥藻分布规律的认识,可为水源地中伪鱼腥藻导致的嗅味问题提供借鉴。     

城市供水水源中抗生素抗性基因污染及其在饮用水厂的去除研究进展

城市供水水源及饮用水厂的水质是关系居民饮用水安全的重要环节.抗生素抗性基因(ARGs)作为一类新兴污染物,近年来在全球各地城市供水水源的污染日益严重,尤其是ARGs检出种类在增多、检出频率和浓度在升高,给居民饮用水安全带来很大威胁.饮用水厂的处理工艺对ARGs的去除、控制更是直接关系到居民的饮用水安全.在对城市饮用水源...     

Five years of air chemistry observations in the Canadian Arctic

Arctic air chemistry observations made in Canada between 1979 and 1984 are discussed. The weekly average concentration of 25 aerosol constituents has been measured routinely at three locations. Anthropogenic pollution typified by SO₄²⁻ and V has a persistent seasonal cycle. SO₄²⁻ concentrations are similar at all three locations, although they tend to be somewhat higher at Alert than at Mould Bay and Igloolik. The seasonal variation of an aerosol constituent depends on its source. There are four distinctive seasonal variations for:

• 1.(i) anthropogenic constituents Cr, Cu, Mn, Ni, Pb, Sr, V, Zn, H⁺, NH₄⁺, SO₄²⁻, NO₃⁻,
• 2.(ii) halogens (excepting Cl) Br, I, F,
• 3.(iii) sea salt elements Na, Mg, Cl and
• 4.(iv) soil constituents Al, Ba, Ca, Fe and Ti. In the Arctic winter, the mean concentrations of anthropogenic aerosol constituents, except SO₄²⁻, are 2–4 times lower than annual mean concentrations in southern Sweden near a major source region. SO₄²⁻ concentrations are only 30% lower mainly because of production from SO₂. Light scattering (b_scat) and SO₄²⁻ observations indicate that the SO₄²⁻ fraction of the fine particle mass fluctuates between 3 and 65% during the polluted winter months. Daily mean b_sact, at Mould Bay that exceeds 50 × 10⁻⁶m⁻¹ is associated with air originating from the northwest. The soluble major ion composition of aerosols during winter varies markedly with particle size. H⁺, NH₄⁺ and SO₄²⁻ dominate submicrometre particles while sea-salt ions Mg²⁺, Na⁺ and Cl⁻ predominate in supermicrometre particles. Winter SO₂ concentrations at Mould Bay and Igloolik ranged from 0.2 to 1.5 ppb
• 5.(v). The fraction of airborne S as SO₂ ranged from 20 to 90% and peaked in late December-early January. The concentration of total NO₃⁻ (0.025–0.090 ppb(v)) is much lower than that of SO₄²⁻ (0.3–1.2 ppb (v)).

     

The search for an alternative to piped water and sewer systems in the Alaskan Arctic

Forty-two communities in rural Alaska are considered unserved or underserved with water and sewer infrastructure. Many challenges exist to provide centralized piped water and sewer infrastructure to the homes, and they are exacerbated by decreasing capital funding. Unserved communities in rural Alaska experience higher rates of disease, supporting the recommendation that sanitation infrastructure should be provided. Organizations are pursuing alternative solutions to conventional piped water and sewer in order to maximize water use and reuse for public health. This paper reviews initiatives led by the State of Alaska, the Alaska Native Tribal Health Consortium, and the Yukon Kuskokwim Health Corporation to identify and develop potential long-term solutions appropriate and acceptable to rural communities. Future developments will likely evolve based on the lessons learned from the initiatives. Recommendations include Alaska-specific research needs, increased end-user participation in the design process, and integrated monitoring, evaluation, and information dissemination in future efforts.     

Investigation of the behavior and metabolism of pharmaceutical residues during purification of contaminated ground water used for drinking water supply

Residues of phenazone-type pharmaceuticals originating from spills of a former pharmaceutical production plant have recently been detected in ground water in Berlin, Germany. The degradation pathways of phenazone, propyphenazone, and dimethylaminophenazone (DMAA) during water purification were enlightened in batch experiments with groundwater and filter material obtained from operating waterworks. For phenazone and propyphenazone a complete biological transformation into their respective metabolites 1,5-dimethyl-1,2-dehydro-3-pyrazolone (DP) and 4-(2-methylethyl)-1,5-dimethyl-1,2-dehydro-3-pyrazolone (PDP) was observed. Generally, removal of phenazone-type pharmaceutical residues during rapid sand filtration was almost exclusively caused by microorganisms only present in polluted raw water. DMAA applied to fresh filter materials was rapidly degraded into its metabolites 1-acetyl-1-methyl-2-phenylhydrazide (AMPH), acetoaminoantipyrine (AAA), formylaminoantipyrine (FAA), and 1-acetyl-1-methyl-2-dimethyloxamoyl-2-phenylhydrazide (AMDOPH). DMAA, AAA, and FAA were, however, only detected at low levels in a few samples of purified water from an operating water works. Whereas, the metabolites AMDOPH and DP were detected up to 1 microg l(-1). Propyphenazone was rapidly removed and AMPH, phenazone, and PDP were only measured with concentrations in the low ng l(-1) range. The concentrations of the metabolites DP and PDP are even higher in the purified water than in the raw water caused by their formation during degradation of phenazone and propyphenazone. Reduction of filtration velocity on an experimental filter from 5 m h(-1) down to 2 m h(-1) resulted in improved removal of phenazone, propyphenazone and their metabolites DP and PDP, respectively. AMDOPH, however, was highly persistent in all experiments independent from filtration velocities and contact times.     

Investigation of the behavior and metabolism of pharmaceutical residues during purification of contaminated ground water used for drinking water supply

Residues of phenazone-type pharmaceuticals originating from spills of a former pharmaceutical production plant have recently been detected in ground water in Berlin, Germany. The degradation pathways of phenazone, propyphenazone, and dimethylaminophenazone (DMAA) during water purification were enlightened in batch experiments with groundwater and filter material obtained from operating waterworks. For phenazone and propyphenazone a complete biological transformation into their respective metabolites 1,5-dimethyl-1,2-dehydro-3-pyrazolone (DP) and 4-(2-methylethyl)-1,5-dimethyl-1,2-dehydro-3-pyrazolone (PDP) was observed. Generally, removal of phenazone-type pharmaceutical residues during rapid sand filtration was almost exclusively caused by microorganisms only present in polluted raw water. DMAA applied to fresh filter materials was rapidly degraded into its metabolites 1-acetyl-1-methyl-2-phenylhydrazide (AMPH), acetoaminoantipyrine (AAA), formylaminoantipyrine (FAA), and 1-acetyl-1-methyl-2-dimethyloxamoyl-2-phenylhydrazide (AMDOPH). DMAA, AAA, and FAA were, however, only detected at low levels in a few samples of purified water from an operating water works. Whereas, the metabolites AMDOPH and DP were detected up to 1 μg l⁻¹. Propyphenazone was rapidly removed and AMPH, phenazone, and PDP were only measured with concentrations in the low ng l⁻¹ range. The concentrations of the metabolites DP and PDP are even higher in the purified water than in the raw water caused by their formation during degradation of phenazone and propyphenazone. Reduction of filtration velocity on an experimental filter from 5 m h⁻¹ down to 2 m h⁻¹ resulted in improved removal of phenazone, propyphenazone and their metabolites DP and PDP, respectively. AMDOPH, however, was highly persistent in all experiments independent from filtration velocities and contact times.     

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。     

臭氧对饮用水管网中溶解性有机物的影响

利用生物膜环状反应器模拟配水管网系统,将水厂砂滤池出水经过臭氧氧化后投加氯然后进入该模拟管网,另外把水厂砂滤池出水加氯后通入另一模拟管网作为对照实验。通过对两管网出水余氯、总铁、浊度、溶解性有机物(DOC)、以及消毒副产物三卤甲烷(THMs)、卤乙酸(HAAs)生成情况的测定,研究了饮用水臭氧处理对管网出水水质的影响。单因素方差分析结果表明,两管网出水的余氯、总铁、浊度以及THMs、HAAs含量相差不大,但DOC在臭氧氯管网中消耗较多。同时通过高效凝胶色谱(HPSEC), 红外光谱(FTIR)和三维荧光光谱(EEM)表征了不同管网进出水DOC变化,结果表明,臭氧氧化后的管网出水中溶解性有机物荧光光谱中三区富里酸和五区腐植酸荧光峰值(ФⅢ+Ⅴ,n)减小较多,管网出水消毒副产物稍有增加。     

Mapping Human Dimensions of Climate Change Research in the Canadian Arctic

This study maps current understanding and research trends on the human dimensions of climate change (HDCC) in the eastern and central Canadian Arctic. Developing a systematic literature review methodology, 117 peer reviewed articles are identified and examined using quantitative and qualitative methods. The research highlights the rapid expansion of HDCC studies over the last decade. Early scholarship was dominated by work documenting Inuit observations of climate change, with research employing vulnerability concepts and terminology now common. Adaptation studies which seek to identify and evaluate opportunities to reduce vulnerability to climate change and take advantage of new opportunities remain in their infancy. Over the last 5 years there has been an increase social science-led research, with many studies employing key principles of community-based research. We currently have baseline understanding of climate change impacts, adaptation, and vulnerability in the region, but key gaps are evident. Future research needs to target significant geographic disparities in understanding, consider risks and opportunities posed by climate change outside of the subsistence hunting sector, complement case study research with regional analyses, and focus on identifying and characterizing sustainable and feasible adaptation interventions.