III. ENVIRONMENT MONITORING AND URBAN PLANNING
[ III-A | III-B | III-C | III-D | III-E | III-F | III-G | III-H ]
A. Environmental quality in Shanghai
[ A | A-1 | A-2 | A-3 | A-4 ]
1. Water Environment
(a) Inshore water quality
According to the monitoring results in the mouth of the Yangtze River and the HangZhou Bay in 1994, the main pollutants in the inshore areas near the above two locations were large amounts of nutrient salt. The average concentration of inorganic N and inorganic P in the mouth of the Yangtze River was 623 ug/L and 207 ug/L respectively; in the HangZhou Bay it was 1039 ug/L and 39.5 ug/L respectively. All exceeded by far the category 1 standard in Sea Water Quality Standard (GB3097-82, GB means national standard). The dissolved oxygen (DO), permanganate value (CODMn), heavy metals (Total Hg, Cu, Pb, Cd) and petroleum all met or exceeded the limits in category 1 standard for the sea water quality.
By annual comparison, the concentration of nutrient salt and petroleum in 1994 was higher than that in 1993 while the others were almost the same. Compared with data obtained in the 1980s, the concentration of dissolved oxygen decreased, but the water quality can comfortably meet the category I sea water quality standard.
(b) Water quality in rivers and lakes
- (i) Dianshan Lake
The Dianshan Lake, which is an important water resource located in the upstream of the Huangpu River, is the only natural lake in the Shanghai region and therefore the major water body monitored over the years. Its water quality directly affects the quality of the drinking water in Shanghai.
According to data from the 13 monitoring sites in the Dianshan Lake, the pH, dissolved oxygen, CODCr, BOD5, volatile phenol, total oxide, total Hg, total Cd, nitrogen nitrate, nitrogen nitrite and chloride are all able to meet the limit of category 1 standard in Environmental Quality Standard for Surface Water (GB3838-88). For instance, whereas the average concentration of dissolved oxygen was 9.26 mg/L, the concentration of Total P and N, which were the main variables affecting the water quality, were 0.11 mg/L and 2.85 mg/L respectively and would, thus, only meet category 3 or category 4 standard. This monitoring result indicated that eutrophication was the main cause of water pollution. In addition, petroleum pollution was relatively heavier and could only meet the category 4 standard. pH in the Dianshan Lake was also higher than the other water bodies in Shanghai because of the relatively higher concentration of unionized ammonia that only met the limit of category 4 standard for water quality.
Figure 15. The yearly variation of main variables of water quality in the Dianshan Lake
- Compared with the monitored data in the 1980s (figure 15), the organic pollutant and degree of eutrophication had increased sharply. The concentration of petroleum has been controlled and the level of heavy metal pollution had slightly increased but was still within the limit of category 2 standard for water quality. The water quality of the Dianshan Lake is generally good.
- (ii) Huangpu River
The monitoring sections along the Huangpu River are fixed at DianFeng, SongPu Bridge, LinJiang waterworks, NanShi waterworks, YangPu Bridge, and Wusong—the mouth of the Huangpu River, where 16 variables are monitored.
In the water source conservation area of the upper reaches of the Huangpu River are located the Diangfeng and Songpu sections, the latter being one of the important under-construction sources of drinking water in Shanghai. Linjiang, however, is the current drinking water source where six variables exceeded the limits in category 3 standard for water quality, of which DO and unionized ammonia were two new ones. The NanShi section and the other two downstream sections represent the most heavily polluted river course, especially at the YangPu Bridge section where six variables exceeded the limits in category 5 standard. Water quality in NanShi and WuShong sections met the limits of category 4 standard with only one variable exceeding the limit in this category.
Water pollution in the Huangpu River is caused mainly by organic pollutants, which are far heavier than heavy metals. The degree of pollution worsens downstream, and the most heavily polluted river course is ChangQiao towards the river mouth of which the pollution is centred around YangPu. On an annual basis, the concentration of all variables reached their peaks during the period 1986 to 1992 and have declined since 1994.
Figure 16. Comparison of DO at each section in the Huangpu River (mg/L)
Figure 17. Comparison of nitrogen ammonia at each section in the Huangpu River (mg/L)
- (iii) Suzhou River
Six sections are fixed along the Suzhou River. They are at BaiHe, Huangdu, Huacao, Beixinjing Bridge, WuNing Road Bridge and Zhejiang Bridge, the last three sections representing the river channel winding through urban area.
The Suzhou River is notorious as the most heavily polluted river in Shanghai. Early in 1920, the beginning of the initial period of modern industrialization in Shanghai, the water in this river had already turned black and foul, as a result of which the ZhaBei waterworks had to move to YangPu at that time to draw water from the Huangpu River. In 1994, the organic pollutants in the urban segment of the Suzhou River, such as dissolved oxygen, permanganate value, COD, BOD5, and unionized ammonia, all exceeded the limits in category 5 standard for water quality. In the upper reaches, they were between category 4 and 5. The most serious aspect was that the COD in the whole river exceeded the limit of category 5. The concentration of the petroleum and volatile phenol was very high, all worse than category 5.
Figure 18. Comparison of BOD5 at each section in the Suzhou River (mg/L)
Figure 19. Comparison of nitrogen ammonia at each section in the Suzhou River (mg/L)
In 1994, the concentration of some monitored variables in the urban segment, such as COD, permanganate value and BOD5, decreased due to the implementation of the Shanghai Sewerage Project Phase 1. However, the concentration of dissolved oxygen and nitrogen ammonia did not show much improvement because of the influence of floor silt. On an annual comparison, the degree of water pollution reached its peak during the period from the mid-1980s to the early 1990s and has been reducing since 1992.
Figure 20. Variation of different variables at Wuning Road Bridge section in the Suzhou River (mg/L, ug/L)
(c) Drinking water quality
Currently there are nine waterworks supplying the central city of Shanghai with a total capacity of 5.572 million m3/d and a serving area of 451.6 km2. Seven waterworks draw water form the middle and lower reaches of the Huangpu River. MinHang waterworks draws water from the upper reaches of the Huangpu River. YuePu waterworks is the only one drawing water from the Yangtze River.
The poor quality of source water is the main problem faced by in Shanghai. In 1994 the concentration of nitrogen ammonia, dissolved oxygen and permanganate value of source water in most waterworks, which was almost the same as that in the mid-1980s, only met the limits in class 4 or class 5 standard for drinking water. Only the water drawn from the Yangtze River by YuePu waterworks met the limits in class 2 standard for drinking water.
However, in 1994 it was gratifying to learn that the average rate of meeting standards by the 3 classes of indices, including altogether 33 variables in manufactured drinking water, reached 99.88 per cent, 91.72 per cent and 98.58 per cent respectively. For pipeline water, the levels of large intestines bacillus, bacterium, turbidity and chloride all met the limits for national class 2 standard for drinking water, reaching 99.9 per cent, 99.67 per cent, 99.86 per cent and 99.98 per cent respectively.