Abstract:

In the light of the situation that odorant in the water source area of Shangshan Village was quite abnormal in Spring getting far beyond the standard for water source (2-Methylisoborneol content in the waterbody was about 16 times higher than the criterion set in the standard), a survey was launched of waterbodies and sediments within the range of 10km2 around the water sources protection zone. Results show that the conventional physical and chemical properties of the waterbodies in the region met the criteria of Grade I and II in the Standard for Surface Water Environment (GB3838-2002); and in the waterbodies and sediments the nutrient salts and algae did not contribute much directly to the odor from the water; Chlorophyll varied between 2.0 ~9.0 g·L^-1 and suspended solids between 20 ~ 40 mg·L^-1 in content, and were in low levels in most of the area. The content of nutrient salts was close to the criteria of Grade II of GB 3838-2002; In the sediments the content of total nitrogen and total phosphorus might reach as high as 3760mg/kg and 468mg/kg^-1, respectively, and the content of Cu and Zn as high as 50.1mg/kg and 115mg/kg^-1, respectively, and the area as a whole was a bit higher in content of the heavy metals. AVS content was also quite high in sludge, and might reach as high as 5.07μmol/g. The odorant in the water and sediment were more than 20 times higher than the standard, and tended to remain so. It was found that blooming of algae caused by eutrophication of the waterbody was not the reason why abnormal odor occurred in the Taihu Lake region in spring; rather the low temperature and rainfalls in spring caused occurrence of density currents in the bottom of the lake, which in turn triggered release of the odorant accumulated in the sludge into the waterbody. This is probably one of the explanations of why abnormal odor occurs in the Taihu Lake in spring.

Key words: Taihu Lake, Water resource area, Non-eutrophication, Odorant, Analysi