| Drinking water quality is an important basis of human health. In recent years, fast development of industry and agriculture leads to soaring wastewater discharging and increasingly serious water pollution, which influence urban quality of water supply.Qingpu District, located in the west of Shanghai, has rich water resources and dense river network. To learn drinking water quality in Qingpu, Shanghai, based on monitoring source and finished water quality of various water plants from 2005 to 2009 in this district, the current research systematically assessed source and finished water quality to find important pollution indices which influenced water quality, put forward corresponding control measures, and provide an important basis for monitoring and scientific management of water quality in Qingpu District.PartⅠResearch on contamination status of source water in Qingpu DistrictTo learn contamination conditions of source water in Qingpu, based on investigation and analysis of yearly change from 2005 to 2009 of industry and enterprise types, amount of wastewater discharging and aquiculture conditions, using detection methods recommended by national Environmental Quality Standards for Surface Water, the current research quarterly monitored source water regular indices of 22 water plants from 2005 to 2009, whose water sources included Dianshan Lake, Taipu River, inland rivers, and groundwater. Source water quality was evaluated using the standard of gradeⅢin national Environmental Quality Standards for Surface Water (GB3838-2006). The results were shown in the following,1. Total number of industries and enterprises increased by 39.82% from 2005 to 2009. In 2005, petroleum and chemical industries were predominant accounting for 17.66% of the total number while in 2009 machinery manufacturing industry and petroleum and chemical industries were predominant accounting for 37.25% and 18.53% of the total number, respectively.2. From 2005 to 2009, total amount of wastewater discharging increased annually, and it increased by nearly 50% in 2005 compared with that in 2009, among which amount of industrial wastewater domestic sewage increased by 16.67% and 29.79%, respectively, hence domestic sewage was the major factor leading to water pollution..3. Aquiculture area decreased by 13.33% in 2009 compared with 2005, which decreased by 5.5% in inland ponds and dropped to zero in ditches.4. In water samples of 2005, six indices of various water sources including pH value, volatile phenol, cyanide, mercury, copper, and cadmium were up to national surface water standard of gradeⅠ, five indices including sulfate, total hardness, iron, manganese, chloride were up to national surface water standard of gradeⅢ, chemical oxygen demand (COD), oxygen demand were up to the standard of gradeⅣ, and ammonia nitrogen was up to the standard of gradeⅤand worse than gradeⅤ. COD, ammonia nitrogen, turbidity, total nitrogen and phosphor were the most frequently over- standard indices.5. In water samples of 2009, six indices of various water sources including pH value, volatile phenol, cyanide, mercury, copper, and cadmium were up to national surface water standard of grade I, indices including manganese, sulfate, total hardness, chloride, fluoride, etc. were relatively stable, up to national surface water standard of gradeⅡ, ammonia nitrogen and COD were up to the standard of gradeⅢ. The conditions of water quality indices exceeding standards were serious in 2005, over-standard frequency was 6.79%, while in 2009 over-standard frequency dropped to 4.24%.6. From 2005 to 2009, water quality source water of Dianshan Lake, Taipu River and inland rivers had a tendency of gradual improvement in Qingpu. Average integration contamination indices of the three types of water source had a downtrend year after year, and the range was 1.97-2.63, which was in the degree of'polluted' and'heavily polluted'. In 2009, average integration contamination indices in all lakes dropped by 25.1% compared with 2005.PartⅡAnalysis of quality of source water for drinking waterBased on the former survey of water contamination status in Qingpu, the current research, using the standard of gradeⅢin national Environmental Quality Standards for Surface Water (GB3838-2006), evaluated various source water quality, the results were as follows,1) The ranking of quality of water body from better to worse was Taipu River>Diansh Lake>groundwater>inland river in Qingpu. 2) From 2005 to 2009, source water quality of Dianshan Lake, Taipu River and inland rivers had an uptrend year after year. In 2005, oxygen demand was up to the standard of grade VI in Dianshan Lake, and ammonia nitrogen was up to the standard of gradeⅤin inland rivers. In 2009, water quality was improved significantly compared with 2005. The indices were basically up to national surface water standard of gradeⅢand limitations of supplemented items of national sources of central drinking water supply, surface water, except the two indices including oxygen demand and ammonia nitrogen.3) The over-standard indices of various water sources were COD, ammonia nitrogen, iron and manganese during high-water period, while COD, ammonia nitrogen, iron and manganese during low-water period.PartⅢResearch on conditions of drinking water pollution in QingpuTo learn drinking water quality and change trend in Qingpu, using detection methods recommended by national Standards of Drinking Water Quality, the current research quarterly monitored regular indices of finished and piped water from corresponding water source, including Dianshan Lake, Taipu River, inland rivers, groundwater. Finished and piped Water quality from different water source was evaluated using Standards of Drinking Water Quality (GB5749-2006). The results were shown in the following.1. Among 26 indices of finished water using Taipu River, Dianshan Lake, inland rivers and groundwater as water source, over-standard rate of COD, ammonia nitrogen, iron, manganese was 75.74%,37.13%,4.70%,17.57%, respectively. Significant difference of ammonia nitrogen concentration existed between finished water from Taipu River and inland rivers. No significant difference existed among finished water from Taipu River, Dianshan Lake and groundwater.2. During low-water period, COD, ammonia nitrogen, manganese, etc. exceeded standards to different extent, and over-standard rate was 75.49%,57.22%, 21.39%, respectively. No significant difference existed among finished water from various water plants.3. During high-water period, COD, ammonia nitrogen, manganese, etc. were major over-standard indices in finished water from various water plants, the over-standard rate was 74.75%,22.82%,15.54%, respectively, and no significant difference existed in finished water from various water sources.4. From 2005 to 2009, major indices of finished water from various water sources experienced an upturn year after year, and became optimal in 2009.Our study demonstrated that major over-standard indices in Qingpu were ammonia nitrogen and COD, accounting for 24.75% and 49.50% of total over-standard items, respectively; ammonia nitrogen and COD of drinking water stemmed from pollution of source water. Thus we suggest protecting water source protection, optimizing of water resources layout, improving water treatment technique and strengthening water supply management in order to improve percent of pass of ammonia nitrogen and COD of drinking water. |
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