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Comprehensive environmental quality monitoring was conducted in 15 districts (counties) of resettlement areas in Chongqing Municipality of the Three Gorges reservoir area in 2006 with major components including water quality, environmental air quality and acoustic environment quality.
8.1 Water Quality Monitoring
In 2006, water quality monitoring work in the resettlement areas included the quality of surface water, backwater in sensitive areas and drinking water sources. Water quality assessment complied with the Environmental Quality Standards for Surface Water (GB3838-2002). The nutrients evaluation of water bodies complied with the "Technical Regulations on Eutrophication Evaluation Method and Grading for Lakes (Reservoirs)" issued by China National Environmental Monitoring Center.
8.1.1 Surface Water Quality
A total of 148 river sections were setup in 50 tributaries of the Yangtze River in 15 districts (counties), 2 rivers and 8 sections more than in 2005. The water quality evaluation covered 20 items such as pH, dissolved oxygen, permanganate index, COD, BOD5, ammonia nitrogen, copper, zinc, fluoride, selenium, arsenic, cadmium, mercury, hexavalent chromium, lead, cyanide, volatile phenol, petroleum, anion surfactant and sulfide.
In 2006, the overall quality of the surface water of the resettlement areas was fairly good with 127 sections meeting or superior to Grade III national water quality standard, accounting for 85.8%, up by 1.5 percentage points compared with that of the last year. There were 13 sections meeting Grade IV standard, 2 sections Grade V and 6 sections failing to meet Grade Vwater quality standards, taking up 8.8%, 1.4% and 4.1% of the total respectively. Major pollutants were ammonia nitrogen, petroleum and COD.
The water quality in low, level and high flow period was good with the section proportion meeting or superior to Grade III standard being 87.1%, 83.1% and 85.7% respectively, up by 3.4, 3.0 and 3.1 percentage points compared with that of 2005. River sections failing to meet Grade III water quality standard were mainly in Banan District and Wanzhou District with the percent of 46.1% and 50.0%.
8.1.2 Water Quality of the Backwater in Sensitive Areas
47 monitoring sections were established in 29 rivers of 9 districts or counties, down by 13 compared with that of 2005. The monitoring covered 11 items such as water transparency, water temperature, pH, dissolved oxygen, permanganate index, BOD5, TN, ammonia nitrogen, nitrate, chlorophyll-a and TP.
¡ñ Water Quality
Six indicators including pH, dissolved oxygen, permanganate index, BOD5, ammonia nitrogen and TP were employed to assess water quality.
In 2006, the overall surface water quality of the backwater in sensitive areas of the resettlement areas was good with 42 sections meeting or superior to Grade III water quality standard, taking up 89.4% of the total, up by 2.7 percentage points than in 2005. There were 1 Grade IV section, 1 Grade V section and 3 sections failing to meet Grade Vwater quality standard, accounting for 2.1%, 2.1% and 6.4%. Major pollutants were BOD5, TP and ammonia nitrogen.
The proportion of monitoring sections meeting or superior to Grade III water quality standard during March-May was 87.2%, 81.1% and 93.0% respectively, up by 1.5 and 4.1 percentage points in March and May and down by 0.3 percentage point in April compared with the same period last year. The sections with relatively poor water quality were mainly in Wanzhou, Fuling District and Wushan County.
¡ñ Nutrition of the Water Bodies
Five items including chlorophyll-a, TP, TN, transparency and permanganate index were employed to evaluate nutrition status of the water bodies.
In 2006, 18 river sections of the backwater in sensitive areas of the resettlement areas were under eutrophication, accounting for 38.3% of the total. Among them, 14 sections were under slight eutrophication, 3 sections intermediate eutrophication and 1 heavy eutrophication, accounting for 29.8%, 6.4% and 2.1% respectively. Five sections were under oligotrophication and 24 sections were under mesotrophic conditions, taking up 10.6% and 51.1% of the total. The trophic state index ranged from 20.99 to 71.07.
8.1.3 Water Quality of Drinking Water Sources
A total of 118 monitoring sites were established at 97 major centralized drinking water sources of 15 districts (county cities) and Class I towns, 20 more than in 2005. Water quality evaluation covered 25 items including water temperature, pH, dissolved oxygen, permanganate index, COD, BOD5, ammonia nitrogen, TP, copper, zinc, fluoride, selenium, arsenic mercury, cadmium, hexavalent chromium , lead, cyanide, volatile phenol, petroleum, anion surfactant, sulfide, sulfate, chloride and nitrate.
In 2006, the water quality of the major collective drinking water sources of the county cities and Class I towns of the resettlement areas was quite satisfactory with 96.9% of them meeting or superior to Grade III standard. The section percent meeting the functional requirement for drinking water sources had 1.0 percentage point rise compared with that of 2005.
8.2 Environmental Air Quality Monitoring
In 2006, monitoring work of environmental air quality of the resettlement areas mainly included the monitoring of urban air quality and precipitation quality.
8.2.1 Environmental Air Quality
A total of 31 air quality monitoring sites were established in the 15 districts (counties) with 32 dust monitoring sites. The main monitoring items included SO2, NO2, TSP and dust. The Ambient Air Quality Standard (GB3095-1996) was applied in the assessment of the environmental air quality.
In 2006, there was certain improvement of urban air quality in the resettlement areas with 12.1% reduction of air pollution index.
The annual average SO2 concentration was 0.042 mg/m3, meeting Grade II air quality standard. The daily average SO2 concentration was 0.001-0.279 mg/m3 with 0.5% of the total failing to meet national air quality standard. The highest daily average was 1.86 times of the limit. Among the 15 districts or counties, the annual average SO2 concentration of 11 districts or counties met Grade II air quality standard, taking up 73.3%.
The annual average NO2 concentration was 0.031mg/m3, meeting Grade II air quality standard. The daily average NO2 concentration was 0.001-0.260 mg/m3 with only 0.1% of 365 days exceeding the daily standard. The highest daily average NO2 concentration was 2.17 times of the limit. All the annual average NO2 concentration of 15 districts or counties met Grade II air quality standard.
The annual average TSP concentration was 0.100 mg/m3, meeting Grade II air quality standard. The daily average TSP concentration was 0.004-0.405 mg/m3 with 10.8% of 365 days going beyond daily standard. The highest daily average exceeded the limit by 1.70 times. Among the 15 districts or counties, the annual average TSP level of 14 met Grade II standard, taking up 93.3%.
The annual average level of dust was 6.47t/km2?month, 0.7 times higher than the reference standard. The maximum level exceeded the limit by 1.51 times. Among the 15 districts or counties, the annual average level of dust of only Shizhu, Wulong and Fengdu County was lower than the reference standard, accounting for 13.3%.
8.2.2 Precipitation Quality
In 2006, 19 precipitation monitoring sites were established in 15 districts (counties) with the collection of 607 rain samples, 336 of which were acid rain samples. The acid rain frequency was 55.4% and amount of acid rain took up 58.3% of total precipitation, up by 0.4 and 1.2 percentage points compared with that of 2005. The pH value of the precipitation ranged from 4.39 to 7.14 with the average of 4.69. In the 15 districts or counties, 10 had annual average precipitation pH value less than 5.60, accounting for 66.7%.
8.3 Monitoring of Acoustic Environment Quality
In 2006, the monitoring of acoustic environmental quality in the resettlement areas included the monitoring of regional environmental noise, traffic noise and functional area noise. The evaluation work complied with the Standard for Urban Regional Environmental Noise (GB3096-93).
8.3.1 Regional Environmental Noise
A total of 1,429 monitoring grids were established in cities and towns of the 15 districts or counties for the monitoring of regional environmental noise, covering 170.77 km2 of built area. 2-3 times monitoring were carried out during May-October.
In 2006, the overall regional acoustic environment of the resettlement area was good with the equivalent sound level at 54.9 dB. Among them, Fengjie County had the highest equivalent sound level at 59.5 dB followed by Wulong County at 59.2 dB with the lowest in Changshou District at 51.2 dB. The noise source was dominated by domestic noises, taking up 53.0%. Traffic noise ranked the second, taking up 26.7%. Among the 1,429 monitoring grids, 1,207 met noise standard accounting for 84.5%. The percentage of monitoring grids meeting Class I, II, III and IV function areas was 48.1%, 86.7%, 100% and 97.9% respectively. Among the 15 districts and counties, only 2 of them had good regional acoustic environment quality, taking up 26.7%.
8.3.2 Traffic Noise
A total of 221 road sections of in the cities (towns) of 15 districts or counties were established to monitor traffic noise with total length of 299.95 km. The traffic noise was monitored 2-3 times during May-October.
In 2006, the overall road traffic noise of the resettlement was relatively good with average equivalent sound level at 68.5 dB. The average traffic flow was 1,049 vehicles per hour. The total length of trunk road with equivalent sound level over 70 dB was 85.09 km, accounting for 28.4% of the total monitored length. 10 districts (counties) out of the 15 had good and rather good traffic noise level, taking up 66.7%.
8.3.3 Noise of Functional Areas
35 monitoring sites were set up in the cities (towns) of the 15 districts or counties to monitor the noise of functional areas, which covered an area of 82.59 km2. The monitoring was conducted 2-3 days in early May to October each month, once an hour.
In 2006, the daytime and night equivalent sound level of the functional areas was 57.7 dB and 48.3 dB respectively, and the equivalent sound level in both the daytime and night was 57.9 dB. The noise level of 12.9% of daytime hours and 28.3% of night hour went beyond the standard. The equivalent sound level of all functional areas met noise standard for both daytime and night with the exception of that (58.0 dB) of Class IV functional area during night, which was 3.0 dB higher than the limit.
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