南宁市主要饮用水源地水环境健康风险分析

为了解南宁市主要饮用水源水环境质量,分析其对人体健康产生风险水平,对2008—2012年南宁市饮用水源水环境质量进行了分析,并采用美国国家环境保护局(USEPA)推荐的健康风险模型对其所引起的健康风险做了初步评价。结果表明,南宁市主要水源地各污染物环境健康风险水平大小顺序为砷氟化物硝酸盐氨氮铁锰,化学致癌物引起的健康风险水平比非致癌物所致的健康风险水平高4个数量级。水源地水环境健康风险水平主要取决于致癌物质健康风险水平。2008—2012年邕江水源地致癌物质总风险水平较高,空间变化不明显,年际变化呈逐年下降趋势。南宁市主要水源地水环境健康风险水平应受到足够的重视,化学致癌物砷应当作为邕江水源地饮用水源需优先治理的污染物,必须在人们饮用之前将其去除,降低环境健康风险。     

赣江河水主离子化学特征和径流效应以及控制机制

赣江发源于我国中南部的江西省,是长江的一大支流,为了客观分析该河流的水化学特征,开展水质评价,对赣江1958～2016年水化学数据进行了收集和分析。结果表明:①Ca~(2+),Na~++K~+,HCO_3~-和SO_4~(2-)是河流中的主要离子,pH值范围为6.0～8.8,TDS范围为15.7～141.0 mg/L,所有离子月变化量与河流流量呈正相关。1980年以前河流流量与SO_4~(2-),NO_3~-和Cl~-的浓度月变化正相关程度高于1980年以后,这表明河水化学特征1980年之前主要是非点源成因,但1980年以后为多种来源的混合。②海盐源Cl~-占河水Cl~-的比例小于19%,硫酸参与硅酸盐岩和碳酸盐岩的风化,反映了1980年以后人为活动有所加强。Cl~-/(Na~++Cl~-)和SO_4~(2-)/(Na~++Cl~-)的增加与江西省国内生产总量、人口、煤炭消耗、肥料用量的关系受废水排放影响。③根据世界卫生组织饮用水标准,赣江的水质符合饮用水标准,但应该警惕Cl~-和NO_3~-浓度在1980年后在持续增加。     

Experimental investigation on water treatment by the combined nano MgO-nanofiltration technique

A combined system using nano MgO and nanofiltration (NF) membrane was established to purify polluted water in this experiment. The turbidity, permanganate index, UVA254, colony counts and the concentrations of NO3-, NO2-, NH4+, Fe, Mn and Mg of the effluents from each unit of this combined system were measured to investigate the pollutant removal of this system. Based on the results obtained, the combined nano MgO-NF system could efficiently remove many kinds of pollutants in this experiment, including organic matter, nitrogen species, heavy metals, suspended solids and bacteria. And the effluents could meet the standard of drinking water. Furthermore, increasing the nano MgO dosage could not elevate the removal ratio of the pollutants, but only increase the Mg content of the effluent. Thus, 0.05 g L(-1) of nano MgO may be a suitable dosage for 2,000 L of polluted water treatment. Also, the operating pressure of NF membrane had no significant effect on pollutant removal when the operating pressure of NF membrane was increased from 0.3 to 0.9 MPa.     

Evaluation of the origin of nitrate influencing the Klju? groundwater source, Serbia

This paper describes the use of the dual isotope method involving δ(15)N and δ(18)O measurements of dissolved nitrates to assess the origin and fate of groundwater nitrate at the Klju? groundwater source, Serbia. A sampling campaign was conducted in September 2007 during flow conditions obtaining groundwater from observation wells and river water fed by a shallow aquifer hosted in alluvial (sandy-gravel) sediments. Nitrate isotope ratios ranged from +5.3 to +16.9‰ and δ(18)O(NO(3)) values varied from -2.3 to +5.0‰. Two major contamination sources were identified with isotopic compositions characteristic for nitrate derived from nitrification of soil organic nitrogen (+5.3 to +7.8‰ for δ(15)N) resulting in nitrate concentrations of 33.6 and 78.8 mg/L and nitrate derived from animal wastes or human sewage, e.g. via septic systems, yielding δ(15)N values of +9.9 to +11.9‰ and elevated nitrate concentrations of 31.2-245.8 mg/L. The occurrence of nitrification and denitrification was also revealed based on concentration and isotope data for dissolved nitrate.     

Denitrification of nitrate-contaminated groundwater using a simple immobilized activated sludge bioreactor

A simple anaerobic-activated sludge system, in which microorganisms are immobilized by a novel functional carrier, was used for removing nitrate in groundwater. The operating conditions, including hydraulic retention time (HRT), C/N ratio, temperature and NO(3)(-)-N loading concentration were investigated. The NO(3)(-)-N concentration, residual chemical oxygen demand (COD) and nitrite accumulation were used as indicators to assess the water quality of the effluent. The anaerobic biomass loading capacity in the carrier was 12.8 g/L and the denitrifying Pseudomonas sp. and Rhodocyclaceae bacterium were dominant among the immobilized microorganisms in the anaerobic-activated sludge. Under operating conditions of HRT= 1.5 h, C/N= 2-3 and T= 16.8-20 °C, the removal efficiency of NO(3)(-)-N exceeded 93%, corresponding to a relatively high denitrification rate of 0.73 kg NO(3)(-)-N m(-3) d(-1), when the NO(3)(-)-N loading concentration was 50 mg/L. The NO(3)(-)-N concentration of the effluent always met regulatory criteria for drinking water (<10 mg/L) in the main developed and developing countries. The effluent COD was also below 10 mg/L. Although some nitrite accumulated (0-1.77 mg/L) during the operating period, it can be decreased through adjusting the operating pH and HRT. The immobilized activated sludge system may be useful for the removal of nitrate from groundwater.     

长江南京段水污染现状及限排总量

通过长江南京段18个水功能区水质的5 a变化趋势,分析主要污染源及其入江排污量,提出了各水功能区限制排污总量和入江污染物削减建议。结果表明:长江南京段2005—2009年期间,83.3%的水功能区达标率均随时间呈下降趋势,2009年83.3%的水功能区所有的水质监测点均没有达到其水质目标;主要污染源头为通江河道,其COD、NH3-N排放量分别占入江排污总量的65.7%、49.9%;工业、企业排污口的COD、NH3-N排放量分别占入江排污总量的20.9%和25.0%。长江南京段水体COD限制排污总量为6.59万t/a,NH3-N限制排污总量为0.26万t/a;需要削减污染物的水功能区包括5个饮用水水源区、1个保留区和3个渔业、农业、工业用水区;削减任务最重的为饮用水水源区,其COD和NH3-N削减率分别在87.0%～99.0%和17.8%～97.4%之间。     

南方岩溶区地下河主要离子浓度变化趋势分析

对我国南方岩溶区典型地下河——官村地下河的降雨量、流量和钾、钠、钙、镁、氯、重碳酸根、硫酸根以及硝酸根离子的浓度进行了两年多的监测和分析。结果显示:地下河的水化学类型为Ca-HCO3型;硝酸根和硫酸根的浓度在雨季大于旱季;钠离子、钙离子、镁离子、重碳酸根离子在雨季浓度降低;钾离子和氯离子浓度的变化没有规律,这些离子浓度的变化受到稀释作用、淋滤作用或岩溶作用和人类活动的控制。与20世纪80年代的离子浓度相比,只有硝酸根和硫酸根的浓度有明显的升高。地下河的水质虽然未超标,但探讨地下河主要离子浓度变化趋势及原因对保护岩溶含水层是非常必要的。     

Hydrological Effects on Relationships Between δ15N of River Nitrate and Land Use in a Rural River Basin,Western Japan

This study aimed to examine how the relationship between δ¹⁵N of nitrate (δ¹⁵N_NO3) in rivers and land use within a river basin changes with varying hydrological conditions. This information would aid in identifying the dominant source contributing to increased nitrate concentrations in rural rivers. For this, δ¹⁵N_NO3 in river water was investigated monthly in the five subbasins of the Hii River basin (area: 911 km²), western Japan, for 1 year and 3 months. There were significant correlations (p < 0.05) between δ¹⁵N_NO3 and the land‐use ratio (i.e. ratios of forested, agricultural and residential areas in a subbasin) for the majority of the observation days, indicating that δ¹⁵N_NO3 reflected land use within the basin. δ¹⁵N_NO3 ranged from +1.4‰ to +8.5‰ and was lower in a subbasin with a higher forested area ratio. We found that the absolute value of the regression slope of the relationship between δ¹⁵N_NO3 and the land‐use ratio decreased with increasing river discharge. This finding demonstrates that differences in δ¹⁵N_NO3 among subbasins with different land‐use compositions became smaller under higher flow conditions. Because δ¹⁵N_NO3 decreased with increasing river discharge, the small absolute value of the regression slope under high flow conditions indicates that forested areas could be the dominant source of river nitrate during high flows in all subbasins investigated regardless of land‐use composition. The results suggest that forested areas make a large contribution to the increase in nitrate concentration in downstream rivers during high flows, because the nitrate concentration increased with increasing river discharge. Copyright © 2014 John Wiley & Sons, Ltd.     

The application of bioremediation: reduction of metal concentrations in river water and COD in distillery effluent.

The major aim of this study was to evaluate and develop artificial bioremediation systems to reduce or remove metal pollutants from contaminated river water and to decrease the chemical oxygen demand (COD) in distillery effluent. Metals were extracted using the nitric acid digestion method, and the concentrations determined using inductively coupled plasma-atomic emission spectrometry. A decrease in metal concentrations was observed for most of the metals analysed in the river water after being pumped through the bioreactor system for approximately two weeks, e.g. Al concentration decreased from 0.75mg.l(-1) to 0.18mg.l(-) and for Ni, from 0.19mg.l(-1) to 0 mg.l(-l). In addition, the COD counts decreased from 2255 mg.l(-1) to a final value of < 150 mg.l(-1) in the distillery effluent. It could thus be concluded that the bioreactor system decreased the COD and metal concentrations in the distillery effluent as well as the river water, respectively. A bioreactor is being evaluated on-site at a wine cellar to reduce COD and will be constructed at a site along the Plankenbrug River.     

Health risks of pollutants in the surface water sources of the centralized drinking water supply in Zhengzhou,China

To evaluate the potential adverse effects caused by pollutants in the surface water sources of drinking water in Zhengzhou, concentrations of 10 elements were measured and their health risks assessed. The results show that only some concentrations of iron, manganese and fluorine are higher than the corresponding environmental quality standards. Risk assessments indicate that risk quotients (all values with carcinogenic effects of arsenic, three values of worst-case of lead and one value of worst-case of fluorine) exceed the limits respectively; one hazard index of fluorine is more than 1; and all 95% of cancer-risk values of arsenic and lead are above 1.0E-6.     

Investigating the spatial-temporal variation of nitrogen cycling in an urban river in the North China Plain

Urban rivers are essential in retaining nutrients, but little is known about nitrogen cycling in these rivers in semiarid areas. We measured chemical and isotopic compositions of ammonium (NH4(+)-N) and nitrate (NO3(-)-N) to investigate spatial-temporal variation of nitrogen cycling in the Fuhe River in the North China Plain. Nitrogen pollution in the river was mainly induced by extra NH4(+)-N inputs which come from the discharges of urban sewage and effluents of wastewater treatment plants in upstream. NH4(+)-N obtained from decomposing organic matter of sediments can diffuse into the overlying water. Intense nitrification then occurs at the terrestrial-aquatic interface. Due to less vegetation in spring and autumn, loss of NH4(+)-N is mainly caused by nitrification. In contrast, significant NH4(+)-N is absorbed by plants in summer. NO3(-)-N generated from nitrification can be denitrified during the study period. The highest NO3(-)-N loss (about 86.3%) was observed in summer. The contribution of NO3(-)-N loss due to denitrification is 44.6%. The remaining 55.4% is due to plant uptake. The results suggested that nitrogen cycling in the river is related to temperature and dry-wet cycles. And vegetation restoration along the river could benefit the incremental improvements to the aquatic ecosystem.     

Evaluation of atmospheric deposition of nitrogen to the Feitsui reservoir in Taipei.

This research studied how the air pollutants of urban areas affect a neighboring reservoir and its water quality. Through the atmospheric dispersion process, air pollutants move from the Taipei metropolitan to the Feitsui reservoir and enter the water body through dry and wet depositions. ISCST3 (Industrial Source Complex Short Term Model), an air quality model, was used to simulate dispersion, dry deposition and wet deposition of the air pollutants. Then the nitrogen loadings to the Feitsui Reservoir were evaluated. The results indicate that wet deposition places a greater burden than dry deposition does on the water body. Wet and dry deposition of NH4+ together make up a rather large proportion of the total pollution. The ranged from 21.9 to 25.2%. Those of nitrate make up a smaller proportion, ranged from 2.0 to 2.3%. If we take indirect deposition into account and calculate the NO3- and NH4+ together, the proportion is 15.9-17.6%.     

拜泉镇城区地下水化学特征分析

拜泉镇区内地下水可划分为第四系松散岩类孔隙潜水和白垩系碎屑岩类孔隙-裂隙承压水两大类型,共采集了11个无机全分析水样(潜水水样点4个,承压水点7个)和4个有机分析水样(均为承压水)。潜水水化学类型以HCO3-C l为主,而承压水水化学类型则以HCO3型水。城区潜水可C l-、NO3-、NO2-、Mn2+、NH4+、TDS、总硬度等指标均超标,而承压水只有Mn2+、NH4+超标,且超标程度低于潜水。可见,研究区潜水的水质已经受到人类生活生产的污染,水质较承压水差。虽然,目前研究区承压地下水所测试的有机物含量均没有超过饮用水标准的限值,但4个地下水样中均检出农药成分"666",这说明了研究区承压水均受到了人类农业生产中使用农药的污染。     

滴灌施肥灌溉的水氮运移数学模拟及试验验证

基于土壤水分运动的动力学方程和溶质运移的对流-弥散方程，建立了不同土壤中地表滴灌施硝酸铵（NH4NO3）时水分和硝态氮运移的数学模型及边界条件。利用商业化软件HYDRUS-2D对模型进行了求解。为了验证所建立的模型，分别在壤土和砂土两种土壤上进行了不同滴头流量、灌水量和肥液浓度下的湿润距离、土壤含水率和硝态氮分布试验。模拟结果与试验数据的对比表明，利用HYDRUS-2D求解所建立的模型得到的湿润距离随时问的变化过程、土壤含水率和硝态氮分布与实测值吻合良好。因此，HYDRUS-2D软件可以作为预测滴灌施肥灌溉条件下水分和氮素在土壤中运移的有效工具。     

峨眉河饮用水源地环境健康风险评价

饮用水水质问题与人民生命健康息息相关,应引起高度重视。河流饮用水环境健康风险评价是将污染物质与人体健康定量地联系起来,能够对化学污染物给人体健康造成危害的可能性及其程度的大小做出科学的估算的一种方法。综合目前国内外河流饮用水环境健康风险评价的研究成果,将环境污染的健康风险评价模型引入到河流饮用水污染健康风险评价中,建立了饮用水环境健康风险评价模式。通过对峨眉山市峨眉河饮用水水源地进行水环境健康风险评价,研究了水源地水环境健康风险问题,得出定量的健康风险指标,为该饮用水水源风险管理和决策提供莺兽依据．依据僻廉风除评价的结果．能够可力Ⅱ科学合l硼士fb括导7k源讹管硼T作．     

Nitrogen fluxes on catchment scale: the influence of hydrological aspects.

In two catchment areas with altogether eight subcatchments characterising different site-specific situations the interaction between anthropogenic activities (e.g. agriculture, nutrition and waste water management), nitrogen emissions and in stream loads as well as concentrations were studied in detail. Groundwater is the most important pathway for nitrogen inputs into surface waters. Denitrification in the soil/subsurface/groundwater system controls the amount of this input to a high extent. Key factors influencing this process are organic carbon availability, geology, precipitation and groundwater recharge rates as well as residence time in groundwater. The MONERIS emission model is a useful tool to quantify these relationships on (sub-)catchment scale. Areas where concentrations in groundwater (e.g. nitrate) tend to be higher due to little dilution with water and might be problematic in respect to limit values for drinking water, are much less relevant in respect to the loads transported to river systems and receiving seas, than regions with high precipitation. In cases with high water availability mainly high loads transported downstream and finally to the receiving sea are a considerable problem. Within a region mainly areas close to river systems contribute to nitrogen discharges to the river system because of the short residence times of the groundwater from these areas and--related to this--a lower influence of denitrification in the groundwater.     

System design and treatment efficiency of a surface flow constructed wetland receiving runoff impacted stream water

This study reported the efficiency of a free water surface flow constructed wetland (CW) system that receives runoff impacted stream water from a forested and agricultural watershed. Investigations were conducted to examine the potential effect of hydraulic fluctuations on the CW as a result of storm events and the changes in water quality along the flow path of the CW. Based on the results, the incoming pollutant concentrations were increased during storm events and greater at the near end of the storm than at the initial time of storm. A similar trend was observed to the concentrations exiting the CW due to the wetland being a relatively small percentage of the watershed (<0.1%) that allowed delays in runoff time during storm events. The concentrations of most pollutants were significantly reduced (p < 0.05) except for nitrate (p = 0.5). Overall, this study suggests that the design of the system could feasibly function for the retention of most pollutants during storm events as the actual water quality of the outflow was significantly better by 21-71% than the inflow and the levels of pollutants were reduced to appreciable levels.     

Impact of summer droughts on water quality of the Rhine River - a preview of climate change?

It is generally recognized that climate change will affect the discharge regime of the Rhine River. Especially the anticipated increase in extreme river discharges (floods and droughts) poses serious problems to water management, both with regard to water quantity and water quality. Water quality effects of climate change are not sufficiently recognized, however. The purpose of this study is to investigate the impact of droughts on the water quality of the River Rhine. Time series of river flow and water quality were analyzed for station Lobith, located at the Dutch-German border. Over the past three decades, three major droughts were identified, occurring in the years 1976, 1991, and 2003. The water quality during these dry years was compared with the water quality in reference years, characterized by average hydrological conditions and similar chemical pollution. Four groups of water quality parameters were investigated: 1, general variables (water temperature, dissolved oxygen, chlorophyll-a); 2, major ions (chloride, sodium, sulfate, fluoride, bromide); 3, nutrients; and 4, heavy metals. It was found that water quality is negatively influenced by (summer) droughts, with respect to water temperature, eutrophication, major ions and heavy metals. Effects on nutrient concentrations were small for ammonium and could not be demonstrated for nitrate, nitrite and phosphate. The decline in water quality during summer droughts is both related to the high water temperatures and to low river discharges (limited dilution of the chemical load from point sources). Moreover, the impact of the 1976 drought on water quality was far more important than that of the 2003 drought, indicating that the impact of droughts on water quality will be greater when the water quality is already poor.     

Lagrangian analysis of the transport and processing of agricultural runoff in the lower Maumee River and Maumee Bay

Lagrangian analyses is used to evaluate the processing of nutrients and sediments during storm runoff events as water moved from the Maumee River loading station at Waterville, OH through the lower river, Maumee Bay and into Lake Erie's western basin. Chemical signatures of storm water at Waterville were used in combination with frequent collections of water at transects along the flow paths to evaluate processing. These signatures consisted of the contrasting chemographs of conservative parameters (chloride and sulfate), dissolved nutrients (dissolved reactive phosphorus (DRP) and nitrate) and particulate substances (suspended solids (SS) and particulate phosphorus (PP)). During low flow, sharp drops in concentrations of chloride and sulfate indicated that mixing zones between river water and bay/lake water occurred at the river mouth. During high flows, the location of the mixing zone between riverine and bay/lake water was indicated by the margin of storm-event sediment plumes, with larger storms extending further into the lake. Steep concentration gradients of DRP and nitrate between high storm water concentrations and low bay/lake water concentrations were also present at the plume margin. The large areas of storm water inside the plume margin contained high DRP and nitrate concentrations but relatively low SS and PP concentrations, due to SS and PP deposition along the flow paths. Because this deposition occurred in water with high DRP concentrations, little of the bioavailable PP was likely to have been released prior to deposition. This storm runoff water provides excellent media for algal growth.     

Nutrient loads and their impacts on chlorophyll a in the Mae Klong River and estuarine ecosystem: an approach for nutrient criteria development

Investigations on the water quality of the Mae Klong River and Estuary were conducted from April 2005 to February 2006 during periods of early-, mid-, and late-loading. Nutrient loads and transfer patterns were studied together with clarification of contaminated sites. The results indicated that NH4+, NO2- + NO3-, Si(OH)4 and PO4(3-) concentrations varied by season and were comparatively high in the mid-loading period. Analysis of DIN:P and Si:P molar ratios indicated that P04(3-) could possibly be a limiting nutrient. Highly contaminated sites were in the middle (Ratchaburi province) and lower (Samut Songkhram province) river zones in which anthropogenic wastewater discharges were significantly (p < 0.05) loaded. Analysis of the DIN and P transfer patterns showed that self-remediation efficiencies were rarely found. The highest DIN and P loads of 23.87 and 4.03 t/day, respectively, were found in Samut Songkhram province. Nutrients were found to contribute to the hypertrophic condition of the lower river and the estuary. The baseline level of chlorophyll a in the upper river was approximately 3.3 microg/L, while levels exceeded 10 microg/L in the estuarine zone. Such chlorophyll a levels were highly significant (p < 0.01) related to DIN and P (with correlation coefficients of 0.44 and 0.37, respectively). In order to maintain river conservation to an acceptable degree, levels of about 20 micromol/L DIN and 1 micromol/L P were suggested as the upper limits. To achieve such levels will require serious consideration with regard to the development of nutrient criteria for water resource conservation management and sustainable utilization purposes.