水库鱼体汞积累的预测

PREDICTION OF FISH MERCURY BIOACCUMULATION IN RESERVOIRS

回归分析表明，在所研究的长江流域的12个水库中，水库与河流鲤鱼汞含量的比值F与水库集水面积A和径流量Q的比值呈显著的负相关：F＝2．5096－0．48047A／Q（r＝0．795，n＝12）凤滩水库调查结果证实了此回归方程的可靠性。实测的F值与预测值比较，相对误差为23．1％。用此模型预测三峡大坝建成蓄水后将加剧鱼体对汞的生物富集作用，局部水域存在鱼体汞含量超过我国食品汞含量标准的可能性。本文讨论了河流与水库中鱼体对砷、汞、硒、铅和镉元素积累的特点。比较其富集系数指出，在同一水系中，河流的鲤鱼对砷和硒的富集能力比水库与湖泊的鲤鱼大，而对汞、镉、铅的富集能力比水库与湖泊的鲤鱼小。

Heavy metal bioaccumulation of fish in rivers and lakes or reservoirs are discussed in relation to background values of elements in fish in Changjiang River water system and the Fengtan Reservoir, Hunan Province. The carp in lakes or reservoirs has greater concentrations than in rivers for Hg, Cd and Pb, and has less concentrations than in rivers for As and Se. F value, which is the fish mercury content in reservoir compared to the content in river within a same river basin, is greater than 1, but smaller than 1 for As and Se.The regression analysis shows that there is a good correlationship tetween F and ratio values of reservoir drainage area(A) to its runoff(Q):F = 2.5096 -0.48047A / Q (r = - 0.795, n = 12)This shows that the smaller values of A / Q, the greater extent of mercury in fish.Comparing calculated F values to measured values, their relative errors are 2.1-40.4%,average relative error is 12.6%. The regression equation is confirmed by results investigated in the Fengtan Reservoir. Measured in field F values are 1.29-1.92 with the mean value 1.60, and the relative error 23.1%. It is well filled with the predicted F value. On the basis of mis regression equation, it is predicted that the bioconcentration of mercury in fish will increase after construction of the Three Gorge Reservoir, contents of mercury will be 1.6-2.0 bine higher than present contents, and there might be a possibility that fish mercury contents might exceed the concentration of 0.3mg / kg which is the limit content of the Food Hygiene Law of the People's Republic of China (tentative). In the high mercury background zone of the low Wujiang River, this will produce the severe impacts on fishery development and community health.