2007-2013年乌鲁木齐市集中式饮用水源地水质变化趋势分析及对策建议

对2007-2013年乌鲁木齐市集中式饮用水源地水质监测数据进行综合分析,泉水型地下饮用水源地米东区三水厂受储水介质及当地地质化学结构的影响,溶解盐类常年超标,水质较差;湖库型地表水源地五、八水厂总磷浓度在个别年份存在一定程度的超标现象,且地表水源地中挥发性卤代烃类、硝基苯和酞酸酯类等有机项目及镍等重金属类检出率较高,存在一定程度的风险。对此提出了进一步完善水源地环境保护及合理开发优质水资源的对策建议,为首府饮用水源地的保护和相关研究工作提供依据。     

Bacteriological quality of drinking water in Nyala, South Darfur, Sudan

The objective of this study was to determine the bacterial contaminations in drinking water in Nyala city, South Darfur, Sudan with special reference to the internally displaced people camps (IDPs). Two hundred and forty water samples from different sites and sources including bore holes, hand pumps, dug wells, water points, water reservoir and household storage containers were collected in 2009. The most probable number method was used to detect and count the total coliform, faecal coliform and faecal enterococci. Results revealed that the three indicators bacteria were abundant in all sources except water points. Percentages of the three indicators bacteria count above the permissible limits for drinking water in all samples were 46.4% total coliform, 45.2% faecal coliform and 25.4% faecal enterococci whereas the highest count of the indicators bacteria observed was 1,600 U/100 ml water. Enteric bacteria isolated were Escherichia coli (22.5%), Enterococcus faecalis (20.42%), Klebsiella (15.00%), Citrobacter (2.1%) and Enterobacter (3.33%). The highest contamination of water sources was observed in household storage containers (20%) followed by boreholes (11.25%), reservoirs (6.24%), hand pumps (5.42%) and dug wells (2.49%). Contamination varied from season to season with the highest level in autumn (18.33%) followed by winter (13.75%) and summer (13.32%), respectively. All sources of water in IDP camps except water points were contaminated. Data suggested the importance of greater attention for household contamination, environmental sanitation control and the raise of awareness about water contamination.     

Multivariate analysis of drinking water quality parameters in Bhopal, India

Pollution of water bodies is one of the areas of major concern to environmentalists. Water quality is an index of health and well being of a society. Industrialization, urbanization and modern agriculture practices have direct impact on the water resources. These factors influence the water resources quantitatively and qualitatively. The study area selected were the Upper lake and Kolar reservoir of Bhopal, the state capital of Madhya Pradesh, India. The Upper lake and Kolar reservoir both are the important sources of potable water supply for the Bhopal city. The physico–chemical parameters like temperature, pH, turbidity, total hardness, alkalinity, BOD, COD, Chloride, nitrate and phosphate were studied to ascertain the drinking water quality.     

Chlorination and water quality monitoring within a public drinking water supply in Rawalpindi Cantt (Westridge and Tench) area, Pakistan

Concern over the presence of fecal coliform in public drinking water supplies has been expressed in recent years in Pakistan since it has been regarded as pathogenic organism of prime importance in gastroenteritis. Two major drinking water distribution systems in the Cantt area of Rawalpindi district covering the Westridge and Tench areas was monitored over a 2-month period to determine the prevalence of fecal coliform and chlorine residual. The collected samples were examined for total chlorine, free chlorine residual, chloramines, total coliforms, fecal coliforms, and turbidity. The drinking water quality monitoring in the distribution network was performed by collecting samples from water source, overhead reservoir, and residential taps. In the Westridge area, total chlorine varied from the lowest value of 0.27 mg/L at Station # W-5 to the highest value of 0.42 mg/L at Station # W-2, total coliforms varied from 1.1 to 3.6 most probable number (MPN)/100 mL with presence of Escherichia coli in all samples, total dissolved solids (TDS) ranged from 199.5 to 205 mg/L, conductivity fluctuated between 399 and 411 microS/cm, and turbidity varied from 0.43 to 0.73 NTU. In the Tench area, the value of total chlorine ranged from 0.14 mg/L at Station # T-7 to 0.55 mg/L at Station # T-1. Total coliform varied from 3.6 to 5.1 MPN/100 mL and fecal coliform were detected at all the stations except at Station # T-1. TDS ranged from 201.4 to 257 mg/L, conductivity varied from 343 to 513 microS/cm, and turbidity ranged between 0.66 and 1.55 NTU. It is recommended to the respective agencies to ensure that the chlorine residual is available at consumer end.     

Evaluation of drinking water treatment and quality in Takua Pa, Thailand

After 2004 Indian Ocean Tsunami, which hit and devastated several Countries in Southeast Asia, University of Brescia and Mahidol University started a project on water monitoring and treatment for drinking purposes in Takua Pa district (Thailand), the most damaged by the tsunami. In particular, this paper presents the results of a study conducted to evaluate the effectiveness of Takua Pa drinking water treatment plant and to identify actions that could be adopted to improve its performances. The results show that, even if the effluent usually meets Thai guide values, except for pH which is already too acid in the influent, the plant needs several structural and managerial improvements, such as filtration and sedimentation upgrade, coagulation/flocculation and final disinfection re-organization, use of proper registers to better plan and control employees activities. Moreover, it was determined that water quality in the distribution network is characterized by turbidity and organic matter values higher than those evaluated in the plant effluent.     

Assessing water quality of drinking water distribution system in the South Taiwan

This investigation conducted a full-scale survey the drinking water distribution system in Kaohsiung city, Taiwan. The aim was to investigate whether the distribution system was capable of maintaining high water quality from the water treatment facilities through to the end user. The results showed that the distribution system can maintain high water quality, except for suitable chlorine residuals. The authors plotted chlorine residual contour maps to identify areas with low chlorine residuals, helping them prioritize sections that must be flushed or renewal. The contour maps also provide sufficient and clear information for locating booster chlorination stations. Contour maps enable water facilities to identify how water quality decays in the distribution systems and the locations of such decay. Water quality decay can be caused by properties of pipeline materials, hydraulic conditions, and/or biofilm thickness. However, understanding the exact reasons is unnecessary because the contour maps provide sufficient information for trouble-shooting the distribution systems.     

Assessment of the school drinking water supply and the water quality in Pingtung County, Taiwan

In this study, a questionnaire survey of school drinking water quality of 42 schools in Pingtung County was conducted according to the water sources, treatment facilities, location of school as well as different grade levels. Among them, 45% of schools used tap water as the main source of drinking water, and the schools using groundwater and surface water as drinking water source account for 29% and 26%, respectively. The schools above senior high school level in the city used tap water as drinking water more than underground water, while the schools under junior high school level in the rural area used surface water as their main source of drinking water. The surface water was normally boiled before being provided to their students. The reverse osmosis system is a commonly used water treatment equipment for those schools using tap water or underground water. Drinking fountain or boiled water unit is widely installed in schools above senior high school level. For schools under junior high school level, a pipeline is stretched across the campus. Relative test shows that the unqualified rate of microbe in water is 26.2%. All parameters for physical and chemical properties and metal content had met the domestic standards except that the turbidity of schools under junior high school level using tap water is slightly higher than the standard value.     

Comparative cancer risk assessment of THMs in drinking water from well water sources and surface water sources

This research evaluates the lifetime cancer risks from trihalomethanes in Tehran's drinking water. The Trihalomethanes were measured in seven different water districts. Sixty-three samples were taken from tap water across the city for 7 months. The samples were analyzed for trihalomethanes using US EPA method 524.2. The average concentration of total trihalomethanes in different districts were between 0.81 and 9.0 μg/L, and the highest concentrations were detected in district 2 at 19.5 μg/L. Total lifetime cancer risks assessment from exposure to trihalomethanes in drinking water (ingestion, inhalation, and skin routes) were performed for people living in different districts in Tehran. The lifetime cancer risk was 7.19 × 10(-5) in district 2 (a more affluent neighborhood) where mostly surface water sources is used to supply drinking water and 9.38 × 10(-6) in district 7 (a less affluent neighborhood) which is mainly supplied with well water sources. Based on the population data, the total expected lifetime cancer cases from exposure to trihalomethanes are 104, 108, 81, 81, 41, 27, and three for districts 1 through 7, respectively. The average lifetime cancer risk was 4.33 × 10(-5) which means a total of 606 lifetime cancer cases for the entire province of Tehran. The highest risk from THMs seems to be from the inhalation route followed by ingestion and dermal contacts.     

Drinking water quality monitoring and surveillance for safe water supply in Gangtok, India

To ascertain the quality of drinking water being supplied, water quality monitoring and surveillance was conducted in Gangtok city at various treatment stages, service reservoirs, distribution network, public standposts, and households. No significant change in raw water quality was observed on day-to-day basis. Residual chlorine was found in the range of nil to 0.2 mg/l in the sump water/finished water. Throughout the year (i.e., during summer, winter, and monsoon seasons), the total coliform and fecal coliform counts were ranged from nil to 7 CFU/100 ml and nil to 3 CFU/100 ml, respectively, in sump water of Selep and VIP complex water treatment plant; however, at consumer end, those were observed as nil to 210 CFU/100 ml and nil to 90 CFU/100 ml, respectively. These variations in bacterial counts among the different service reservoirs and consumer ends may be attributed to the general management practices for maintenance of service reservoirs and the possibility of enroute contamination. Evaluation of the raw water quality indicates that the water is suitable for drinking after conventional treatment followed by disinfection. The finished water quality meets the level of standards described as per Bureau of Indian Standard specifications (BIS:10500 1991) for potability in terms of its physicochemical characteristics.     

Assessment of ground water quality for drinking purpose, District Nainital, Uttarakhand, India

The ground water quality of District Nainital (Uttarakhand, India) has been assessed to see the suitability of ground water for drinking and irrigation applications. This is a two-part series paper and this paper examines the suitability of ground water including spring water for drinking purposes. Forty ground water samples (including 28 spring samples) were collected during pre- and post-monsoon seasons and analyzed for various water quality constituents. The hydrochemical and bacteriological data was analyzed with reference to BIS and WHO standards and their hydrochemical facies were determined. The concentration of total dissolved solids exceeds the desirable limit of 500 mg/L in about 10% of the samples, alkalinity values exceed the desirable limit of 200 mg/L in about 30% of the samples, and total hardness values exceed the desirable limit of 300 mg/L in 15% of the samples. However, no sample crosses the maximum permissible limit for TDS, alkalinity, hardness, calcium, magnesium, chloride, sulfate, nitrate, and fluoride. The concentration of chloride, sulfate, nitrate, and fluoride are well within the desirable limit at all the locations. The bacteriological analysis of the samples does not show any sign of bacterial contamination in hand pump and tube-well water samples. However, in the case of spring water samples, six samples exceed the permissible limit of ten coliforms per 100 ml of sample. It is recommended that water drawn from such sources should be properly disinfected before being used for drinking and other domestic applications. Among the metal ions, the concentration of iron and lead exceeds the permissible limit at one location whereas the concentration of nickel exceeds the permissible limit in 60 and 32.5% of the samples during pre- and post-monsoon seasons, respectively. The grouping of samples according to their hydrochemical facies indicates that majority of the samples fall in Ca–Mg–HCO₃ hydrochemical facies.     

Studies on urban drinking water quality in a tropical zone

Anthropogenic activities associated with industrialization, agriculture and urbanization have led to the deterioration in water quality due to various contaminants. To assess the status of urban drinking water quality, samples were collected from the piped supplies as well as groundwater sources from different localities of residential, commercial and industrial areas of Lucknow City in a tropical zone of India during pre-monsoon for estimation of coliform and faecal coliform bacteria, organochlorine pesticides (OCPs) and heavy metals. Bacterial contamination was found to be more in the samples from commercial areas than residential and industrial areas. OCPs like α,γ-hexachlorocyclohexane and 1,1 p,p-DDE {dichloro-2, 2-bis(p-chlorophenyl) ethene)} were found to be present in most of the samples from study area. The total organochlorine pesticide levels were found to be within the European Union limit (0.5 μg/L) in most of the samples. Most of the heavy metals estimated in the samples were also found to be within the permissible limits as prescribed by World Health Organization for drinking water. Thus, these observations show that contamination of drinking water in urban areas may be mainly due to municipal, industrial and agricultural activities along with improper disposal of solid waste. This is an alarm to safety of public health and aquatic environment in tropics.     

Monitoring of ambient particles and heavy metals in a residential area of Seoul, Korea

In this study, ambient TSP, PM10, and PM2.5 in a residential area located in the northern part of Seoul were monitored every other month for 1 year from April 2005 to February 2006. The monthly average levels of TSP, PM10, and PM2.5 had ranges of 71∼158, 40∼106, and 28∼43 μg/m³, respectively. TSP and PM10 showed highest concentration in April; this seems to be due to Asian dust from China and/or Mongolia. However, the fine particle of PM2.5 showed a relatively constant level during the monitoring period. Heavy metals in PM 10 and PM2.5, such as Cr, As, Cd, Mn, Zn and Pb, were also analysed during the same period. The monthly average concentrations of heavy metal in PM2.5 were Cr:1.9∼22.7 ng/m³; As:0.9∼2.5 ng/m³; Cd: 0.6∼7 ng/m³; Mn:6.1∼22.6 ng/m³; Zn: 38.9∼204.8 ng/m³, and Pb: 21.6∼201.1 ng/m³. For the health risk assessment of heavy metals in ambient particles, excess cancer risks were calculated using IRIS unit risk. As a result, the excess cancer risks of chromium, cadmium, and arsenic were shown to be more than one per million based on the annual concentration of heavy metals, and chromium showed the highest excess cancer risk in ambient particles in Seoul.     

Temporal and spatial variability in water quality of wetlands in the Minneapolis/St. Paul,MN metropolitan area: Implications for monitoring strategies and designs

Temporal and spatial variability in wetland water-quality variables were examined for twenty-one wetlands in the Minneapolis/St. Paul metropolitan area and eighteen wetlands in adjacent Wright County. Wetland water quality was significantly affected by contact with the sediment (surface water vs. groundwater), season, degree of hydrologic isolation, wetland class, and predominant land-use in the surrounding watershed (p<0.05). Between years, only nitrate and particulate nitrogen concentrations varied significantly in Wright County wetland surface waters. For eight water-quality variables, the power of a paired before-and-after comparison design was greater than the power of a completely randomized design. The reverse was true for four other water-quality variables. The power of statistical tests for different classes of water-quality variables could be ranked according to the predominant factors influencing these: climate factors>edaphic factors>detritivory>land-use factors>biotic-redox or other multiple factors.For two wetlands sampled intensively, soluble reactive phosphate and total dissolved phosphorus were the most spatially variable (c.v.=76–249%), while temperature, color, dissolved organic carbon, and DO were least variable (c.v.=6–43%). Geostatistical analyses demonstrated that the average distance across which water-quality variables were spatially correlated (variogram range) was 61–112% of the mean radius of each wetland. Within the shallower of the two wetlands, nitrogen speciation was explained as a function of dissolved oxygen, while deeper marsh water-quality variables were explained as a function of water depth or distance from the wetland edge. Compositing water-quality samples produced unbiased estimates of individual sample means for all water quality variables examined except for ammonium.     

Statistical needs in national water quality monitoring programs

The concept that a few well chosen, strategically placed, water quality stations can provide valuable scientific information to water managers is common to many countries. Historically within Canada, water quality regional networks (Great Lakes network, Prairie Provinces Water Board network, Long Range Transport of Airborne Pollutants network, etc.) have been successfully operating for many years. This paper will describe the difficulties associated with developing a national water quality network for a country the size of Canada. In particular, it will describe some of the statistical tools presently being used in regional networks which are suitable for a national network, and discuss the need to develop new statistical tools for environmental monitoring in the 1990's.     

Modelling of lindane transport in groundwater of metropolitan city Vadodara,Gujarat, India

Migration pattern of organochloro pesticide lindane has been studied in groundwater of metropolitan city Vadodara. Groundwater flow was simulated using the groundwater flow model constructed up to a depth of 60 m considering a three-layer structure with grid size of 40?×?40?×?40 m³. The general groundwater flow direction is from northeast to south and southwest. The river Vishwamitri and river Jambua form natural hydrologic boundary. The constant head in the north and south end of the study area is taken as another boundary condition in the model. The hydraulic head distribution in the multilayer aquifer has been computed from the visual MODFLOW groundwater flow model. TDS has been computed though MT3D mass transport model starting with a background concentration of 500 mg/l and using a porosity value of 0.3. Simulated TDS values from the model matches well with the observed data. Model MT3D was run for lindane pesticide with a background concentration of 0.5?μg/l. The predictions of the mass transport model for next 50 years indicate that advancement of containment of plume size in the aquifer system both spatially and depth wise as a result of increasing level of pesticide in river Vishwamitri. The restoration of the aquifer system may take a very long time as seen from slow improvement in the groundwater quality from the predicted scenarios, thereby, indicating alarming situation of groundwater quality deterioration in different layers. It is recommended that all the industries operating in the region should install efficient effluent treatment plants to abate the pollution problem.     

Evaluation of groundwater quality and its suitability for drinking and agricultural use in Thanjavur city, Tamil Nadu, India

As groundwater is a vital source of water for domestic and agricultural activities in Thanjavur city due to lack of surface water resources, groundwater quality and its suitability for drinking and agricultural usage were evaluated. In this study, 102 groundwater samples were collected from dug wells and bore wells during March 2008 and analyzed for pH, electrical conductivity, temperature, major ions, and nitrate. Results suggest that, in 90% of groundwater samples, sodium and chloride are predominant cation and anion, respectively, and NaCl and CaMgCl are major water types in the study area. The groundwater quality in the study site is impaired by surface contamination sources, mineral dissolution, ion exchange, and evaporation. Nitrate, chloride, and sulfate concentrations strongly express the impact of surface contamination sources such as agricultural and domestic activities, on groundwater quality, and 13% of samples have elevated nitrate content (>45 mg/l as NO₃). PHREEQC code and Gibbs plots were employed to evaluate the contribution of mineral dissolution and suggest that mineral dissolution, especially carbonate minerals, regulates water chemistry. Groundwater suitability for drinking usage was evaluated by the World Health Organization and Indian standards and suggests that 34% of samples are not suitable for drinking. Integrated groundwater suitability map for drinking purposes was created using drinking water standards based on a concept that if the groundwater sample exceeds any one of the standards, it is not suitable for drinking. This map illustrates that wells in zones 1, 2, 3, and 4 are not fit for drinking purpose. Likewise, irrigational suitability of groundwater in the study region was evaluated, and results suggest that 20% samples are not fit for irrigation. Groundwater suitability map for irrigation was also produced based on salinity and sodium hazards and denotes that wells mostly situated in zones 2 and 3 are not suitable for irrigation. Both integrated suitability maps for drinking and irrigation usage provide overall scenario about the groundwater quality in the study area. Finally, the study concluded that groundwater quality is impaired by man-made activities, and proper management plan is necessary to protect valuable groundwater resources in Thanjavur city.     

Economics of place-based monitoring under the safe drinking water act, part III: performance evaluation of place-based monitoring strategies

The goals of environmental legislation and associated regulations are to protect public health, natural resources, and ecosystems. In this context, monitoring programs should provide timely and relevant information so that the regulatory community can implement legislation in a cost-effective and efficient manner. The Safe Drinking Water Act (SDWA) of 1974 attempts to ensure that public water systems (PWSs) supply safe water to its consumers. As is the case with many other federal environmental statutes, SDWA monitoring has been implemented in relatively uniform fashion across the USA. In this three part series, we present over 30 years of evidence to demonstrate unique patterns in water quality contaminants over space and time, develop alternative place-based monitoring approaches that exploit such patterns, and evaluate the economic performance of such approaches to current monitoring practice. Part III: Place-based (PBA) and current SDWA monitoring approaches were implemented on test datasets (1995-2001) from 19 water systems and evaluated based on the following criteria: percent of total detections, percent detections above threshold values (e.g. 20, 50, 90% of MCL), and cost. The PBA outperformed the current SDWA monitoring requirements in terms of total detections, missed only a small proportion of detections below the MCL, and captured all detections above 50% of the MCL. Essentially the same information obtained from current compliance monitoring requirements can be gained at approximately one-eighth the cost by implementing the PBA. Temporal sampling strategies were implemented on test datasets (1995-2001) from four water systems and evaluated by the following criteria: parameter estimation, percent deviation from "true" 90th, 95th, and 99th percentiles, and number of samples versus accuracy of the estimate. Non event-based (NEB) strategies were superior in estimating percentiles 1-50, but underestimated the higher percentiles. Event-based strategies were superior in estimating 95th and 99th percentiles, and required significantly fewer samples (than NEB strategies) to estimate the "true" 95th and 99th percentiles. Incorporation of place-based information significantly improves the performance of monitoring and temporal sampling strategies in the context of surface-influenced water systems in the state of Iowa. Application of similar methods to other areas and types of water systems would likely produce similar results. Compared to current SDWA monitoring, the place based approach allows for cost-effective, enhanced characterization of local contaminants of concern.     

Assessing temporal representativeness of water quality monitoring data

The effectiveness of different monitoring methods in detecting temporal changes in water quality depends on the achievable sampling intervals, and how these relate to the extent of temporal variation. However, water quality sampling frequencies are rarely adjusted to the actual variation of the monitoring area. Manual sampling, for example, is often limited by the level of funding and not by the optimal timing to take samples. Restrictions in monitoring methods therefore often determine their ability to estimate the true mean and variance values for a certain time period or season. Consequently, we estimated how different sampling intervals determine the mean and standard deviation in a specific monitoring area by using high frequency data from in situ automated monitoring stations. Raw fluorescence measurements of chlorophyll a for three automated monitoring stations were calibrated by using phycocyanin fluorescence measurements and chlorophyll a analyzed from manual water samples in a laboratory. A moving block bootstrap simulation was then used to estimate the standard errors of the mean and standard deviations for different sample sizes. Our results showed that in a temperate, meso-eutrophic lake, relatively high errors in seasonal statistics can be expected from monthly sampling. Moreover, weekly sampling yielded relatively small accuracy benefits compared to a fortnightly sampling. The presented method for temporal representation analysis can be used as a tool in sampling design by adjusting the sampling interval to suit the actual temporal variation in the monitoring area, in addition to being used for estimating the usefulness of previously collected data.     

Evaluation of water quality index for drinking purposes for river Netravathi, Mangalore, South India

An attempt has been made to develop water quality index (WQI), using six water quality parameters Dissolved oxygen (DO), Biochemical oxygen Demand (BOD), Most Probable Number (MPN), Turbidity, Total Dissolved Solids (TDS) and pH measured at eight different stations along the river basin. Rating curves were drawn based on the tolerance limits of inland waters and health point of view. Bhargava WQI method and Harmonic Mean WQI method were used to find overall WQI along the stretch of the river basin. Five point rating scale was used to classify water quality in each of the study areas. It was found that the water quality of Netravathi varied from Excellent to Marginal range by Bhargava WQI method and Excellent to Poor range by Harmonic Mean WQI method. It was observed that the impact of human activity was severe on most of the parameters. The MPN values exceeded the tolerable limits at almost all the stations. It was observed that the main cause of deterioration in water quality was due to the lack of proper sanitation, unprotected river sites and high anthropogenic activities.