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Comprehensive environmental quality monitoring was conducted in 15 districts (counties) of the migration resettlement area in Chongqing Municipality of the Three Gorges Reservoir area. The major components of the monitoring work were water quality, environmental air quality and acoustic environment quality.
8.1 Water Quality Monitoring
Water quality monitoring work includes the monitoring of surface water quality, water quality of both backwater in sensitive areas and drinking water sources. Water quality evaluation standard and testing methods employed were in accordance with the "Environmental Quality Standards for Surface Water (GB3838-2002)". The nutrition evaluation of water bodies complies with the "Technical Regulations on the Assessment Method and Classification Eutrophication of Lakes (Reservoirs)" issued by the China National Environmental Monitoring Center.
8.1.1 Surface water quality
A total of 130 river sections were set up in 47 rivers of 15 districts (counties) to carry out 3 monitoring activities, one in dry period, one in level water period and one in high water period. The assessment covered 20 items such as pH value, 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. The evaluation results were as the followings:
The overall surface water quality in the migration resettlement area was fairly good in 2004. 107 sections met or were superior to Grade III water quality standard, taking up 82.3% of the total. 11 sections met Grade IV water quality standard, 1 met Grade V water quality standard and 11 failed to meet Grade V water quality standard, accounting for 8.5%, 0.8% and 8.5% of the total respectively. Major pollutants were ammonia nitrogen, petroleum and COD.
The water quality in low, level and high water season was all good, with 82.9%, 78.0% and 82.0% of all the sections monitored meeting or superior to Grade III water quality standard respectively. Nevertheless, water quality in level water period was slightly worse than that of other times. The river sections subject to pollution were mainly in the districts of Banan, Changshou and Wanzhou with 85.7%, 63.6% and 61.5% of the sections exceeding national water quality standard.
The surface water quality in the migration resettlement areas in 2004 was better than that of the previous year, with the proportion of river sections meeting or being superior to Grade III water quality standard increased by 21.1 percentage points.
8.1.2 Water quality of backwater in sensitive areas
49 river sections were established in 26 rivers of 8 districts (counties). Monitoring work on water quality of backwater in sensitive areas was conducted once in the early, mid and late March, April and May of 2004 totaling 9 times. The monitoring covered 11 items of water transparency, water temperature, pH value, dissolved oxygen, permanganate index, BOD5, total nitrogen, ammonia nitrogen, nitrate, chlorophyll a and total phosphorus.
¡ñ Water quality
Six items including pH value, dissolved oxygen, permanganate index, BOD5, ammonia nitrogen, and total phosphorus were employed to assess water quality. The assessment findings were as follows.
The overall surface water quality of the backwater in sensitive areas of the migration resettlement area was quite good in 2004. 43 river sections met or were superior to Grade III water quality standard, taking up 87.8% of the total. One section met Grade IV standard and 5 failed to meet grade V standard, accounting for 2.0% and 10.2% respectively. Major pollutants in the water were ammonia nitrogen and total phosphorus.
As the comparison of the water quality in March, April and May showed, the water quality in March and May was relatively better with 82.8% and 89.6% of river sections meeting or being superior to Grade III water quality standard. In contrast, the water quality in April was a little worse with only 75.6% sections meeting or being superior to Grade III water quality standard. The sections with relatively poor water quality were mainly in Wanzhou District and Wushan County.
The water quality of the backwater in sensitive areas dropped to some extent compared with that of 2003, with the proportion of sections meeting or being superior to Grade III water quality standard decreasing by 8.1 percentage points.
¡ñ Nutrition status of the water bodies
Five items including chlorophyll a, total phosphorus, total nitrogen, water transparency and permanganate index were employed to assess the nutrition status of the water body with the assessment results as follows.
The water body of 14 river sections was of eutrophication, accounting for 28.5% of the total. Among them, 11 were of slight to medium eutrophication, 3 of intermediate eutrophication, accounting for 22.4% and 6.1% of the total respectively. Nine sections were of poor nutrition and 26 sections were of medium nutrition, taking up 18.4% and 53.1% respectively. The nutrition status index of the water bodies ranged from 12.86 to 67.97.
8.1.3 Water quality of drinking water sources
A total of 84 monitoring sites were set up in all major centralized drinking water sources of Class I towns in 15 districts (counties), 66 of which were river sections and 18 were in reservoirs that were drinking water sources. County city drinking water source was monitored once a month, totally 12 times throughout the year. The drinking water sources of towns were monitored once in the low water season, once in level and once in high water season, totaling 3 times throughout the whole year. The assessment contents covered 23 basic water environmental items set forth in the "Environmental Quality Standards for Surface Water (GB3838-2002)"(excluding total nitrogen) and the additional 3 items including sulfate, chloride and nitrate (calculated in nitrogen) totaling 26 items. The assessment results were as follows.
In 2004, the water quality of the drinking water sources in the migration resettlement areas was quite satisfactory with the quality of all drinking water sources meeting or being superior to Grade III water quality standard. Compared with the previous year, the proportion of sections meeting the functional requirements for drinking water source rose by 4.1 percentage points. To be specific, the proportion of sections meeting Grade I and III water quality standard rose by 6.0 percentage points and 15.3 percentage points respectively while the proportion of sections meeting Grade II water quality standard dropped by 17.2 percentage points.
8.2 Environmental Air Quality Monitoring
The monitoring of environmental air quality of the migration resettlement areas was mainly composed of the monitoring of urban air quality and precipitation quality.
8.2.1 Air quality
A total of 30 air quality monitoring sites and 31 dust monitoring sites were established in 14 districts (counties) except for Wuxi County. The key monitoring items included SO2, NO2, total suspended particles (TSP) and dust. For SO2, NO2 and total suspended particles, 24-hour continuous sample collection was carried out for laboratory analysis. Their samples were collected at least 18 hours a day and 3 days a week. As for dust, the monitoring was conducted for a consecutive month with sample collected and analyzed each month. The "Ambient Air Quality standard (GB3095-1996)" was applied in the evaluation of environmental air quality.
The annual average concentration of sulfur dioxide in 2004 was 0.046 mg/m3, meeting Grade II national air quality standard. The daily average concentration of SO2 was 0.001 ~ 0.415 mg/m3 with 1.2% of the total failed to meet national air quality standard. The highest daily average level of SO2 was 1.77 times higher than the standard value. Among the 14 districts (counties) monitored, the annual average level of sulfur dioxide of 11 districts (counties) met Grade II national air quality standard, accounting for 78.6% of the total.
The annual average concentration of nitrogen dioxide in 2004 was 0.031 mg/m3, meeting Grade II national air quality standard. Its daily average level ranged from 0.001 to 0.201 mg/m3, and 0.2% of the total failed to meet the national daily average standard. The highest daily average concentration of NO2 was 0.68 times higher than the standard value. The annual average concentration of NO2 in the air of all the 14 districts (counties) met Grade II national air quality standard.
The annual average concentration of total suspended particles (TSP) in 2004 was 0.167 mg/m3, meeting Grade II national air quality standard. Its daily average level ranged from 0.004 to 0.610 mg/m3, 2.9% of the total failed to meet the national daily average standard. The highest daily average level was 1.03 times higher than the standard. Among the 14 districts (counties) monitored, the annual average level of TSP of 13 districts (counties) met Grade II national air quality standard, accounting for 92.9% of the total.
The annual average level of dust was 6.81 ton/km2¡¤month, 0.59 times higher than the reference standard. The peak amount was 1.33 times higher than the standard value. Among all the 14 districts (counties) monitored, only Wulong County and Fengdu County met relevant national standard, taking up only 14.3% of the total.
8.2.2 Precipitation quality
A total of 18 precipitation quality monitoring sites were set up in 15 districts (counties), among which 2 monitoring sites were set up in Wanzhou District, Fuling District and Jiangjin City respectively while 1 site was set up in each of the rest districts (counties). A monthly monitoring was carried out in Wanzhou District and Fuling District while the monitoring work in other districts (counties) was carried out in January, April, July, August and October when there was precipitation.
732 precipitation samples were collected in all the 18 monitoring sites. Among them, 397 were acid rain samples with the frequency of 54.2%. The amount of acid rain accounted for 47.1% of the total precipitation volume. The pH value of the precipitation tested ranged from 3.37 to 7.95, with an averaging of 4.87. Among all the 15 districts (counties) monitored, the annual average pH value of 9 districts (counties) was under 5.60, accounting for 60.0%.
8.3 Acoustic Environmental Quality Monitoring
The monitoring of acoustic environmental quality in the migration resettlement areas included the monitoring of regional environmental noise, traffic noise and functional area noise. The evaluation work complies with the "Standard of Environmental Noise of Urban Area (GB3096-93)".
8.3.1 Regional environmental noise
A total of 1,574 monitoring grids were established in the towns of 15 districts (counties), covering 86.06 km2 of established urban area. The regional environmental noise monitoring was carried out once in May.
Monitoring results showed that the overall regional environmental acoustic quality was under slight pollution with the equivalent sound level of 58.0 dB. Among all the districts (counties) monitored, the equivalent sound level of Kaixian County was the highest at 66.1 dB followed by Wushan County at 63.8 dB. Changshou District was the lowest at 52.8 dB. The source of noises was mainly from social life and domestic noises, accounting for 58.9% of the total. Traffic noise took the second, taking up 25.9%. Among the 1,574 monitoring grids, 1,108 grids met the relevant national noise standard, accounting for 70.4%. The grid noise up-to-standard rate of Grade I, II, III and IV region was 39.0%, 70.5%, 96.4% and 82.0% respectively. In the 15 districts (counties), only 3 enjoyed relatively good acoustic environment, accounting for 20.0% of the total. The up-to-standard rate of grid noise of Changshou Distrcit was the highest of 100%, while that of Kaixian County was the lowest of 25.2%.
8.3.2 Traffic Noise
A total of 187 road sections were set up in 15 districts (counties) for the monitoring of traffic noise, covering a total length of 250.90 km. Traffic noise monitoring was carried out once in May.
Monitoring findings indicated that the overall road traffic acoustic quality was relatively good with average equivalent sound level being 69.1 dB. The average traffic flow was 1,274 vehicle/hour; and the total length of trunk road with equivalent sound level over 70 dB was 96.71 km, accounting for 36.55% of the total. 10 districts (counties) out of the 15 had rather good traffic acoustic environment, taking up 66.7% of the total.
8.3.3 Noise of functional areas
35 monitoring sites were set up in the towns of 15 districts (counties) to monitor the environmental noise functional areas, covering an area of 76.33 km2. A one-day (24 hours) monitoring was conducted in early June and early November respectively, the noise was monitored once every hour. The findings showed that daytime and nighttime equivalent sound levels of the functional areas was 58.7 dB and 48.8 dB respectively, and the equivalent sound level in both the daytime and nighttime was 58.8 dB, all meeting relevant national noise standard. However, 32.7% of hours during daytime and 44.5% of nighttime hours cannot meet the hourly national noise standard. The equivalent sound level of all regions met relevant national noise standard for both daytime and nighttime with the exception of that (59.7 dB) of Class IV region during nighttime, which was 4.7 dB higher than the standard.
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