[Heavy metals accumulation in river sediments of Chongming Island, Shanghai City, and its environmental risk].

Heavy metals accumulation in river sediments can reflect the environmental quality of river waters. It's of practical significance to study the accumulation level of heavy metals in river sediments and its environmental risk. In this paper, the heavy metals accumulation in river sediments of three typical towns of Chongming Island was studied, and the results showed that the average accumulation of Zn, Cr, Cu, Pb and Cd in Chengqiao Town, Baozhen Town and Chenjia Town was 103.1, 79.2, 39.0, 29.7 and 0.300 mg x kg(-1), 99.0, 104.0, 50.5, 32.7 and 0.308 mg x kg(-1), and 86.7, 79.5, 32.2, 30.5 and 0.274 mg x kg(-1), respectively. In South Chongming, the average accumulation of Zn, Cr, Cu, Pb and Cd was 94.72, 81.35, 38.52, 30.78 and 0.297 mg x kg(-1), respectively. The environmental risk assessment by using geoaccumulation index (I(geo)) indicated that these three towns had a low-medium rank environmental risk of heavy metals accumulation in river sediments, and the probability of achieving medium rank risk was in the order of Chengqiao > Baozhen > Chenjia.

[Heavy metal content and ecological risk warning assessment of vegetable soils in Chongming Island, Shanghai City].

In order to determine the content of copper (Cu), lead (Pb), chromium (Cr), zinc (Zn) and cadmium (Cd) in vegetable field, soil samples were collected from three towns of Chongming Island, an important ecotypic island of Shanghai City. The average content of Cu, Zn, Pb, Cr and Cd in vegetable soil of the three towns is 29.2 mg x kg(-1), 91.2 mg x kg(-1), 26.5 mg x kg(-1), 79.4 mg x kg(-1) and 0.222 mg x kg(-1), respectively. Except for the content of Cd exceeded the first grade of national soil standard (GB 15618-1995), the contents of the other four heavy metals were less than the first grade of the standard, and the content of heavy metals in this fireld met the request of heavy metal level to produce green foods (NY/T 391-2000). The contents of Cu, Pb, Cr, Zn and Cd in the vegetable soils are 24.3%, 24.4%, 22.9%, 18.8% and 65.7% higher than the background value of Shanghai, respectively. The result of ecological risk warning assessment showed that three sampling sites were medium warning situation, ten were light warning situation, eight were warning situation and one was no warning, in all the 23 sampling sites. The total situation of Chongming Island was light warning, and the I(ER) = 1.562. The order of ecological risk was Baozhen town (I(ER) = 1.799) > Chengqiaozhen town (I(ER) = 1.636) > Chenjiazhen (I(ER) = 1.368). The three towns were all light warning situation.