关键词: 上覆水, 孔隙水, 沉积物, 重金属

Abstract: Natural freshwater sediment and water column samples were collected from Wuhan section along the Yangtze River and Zhengzhou section along the Yellow river in Oct. 2000. These sediment samples were spiked with Cu, Pb, Zn, Cd. The water column and the interstitial waters were spiked with Cu, Pb, Zn, Cd, Ni in the laboratory. The Vibrio qinghaiensis sp. Q-67 and the cladoceran Daphnia magna were introduced as test species in both solid- and liquid- phases toxicity bioassays. Based on the EC₅₀/LC₅₀measured and calculated in bioassays, the toxicity differences of the sediment and water column samples between the representative sections along the Yangtze and Yellow rivers were evaluated. The natural water column and the natural interstitial waters from both sections have no acute toxicity effects on the Vibrio qi nghaiensis sp. Q-67, however, the 96 h acute toxicity effect of natural sediment from the Yangtze river on Daphnia magna is evident. The acute toxicity effects of all the five heavy metals-spiked interstitial waters collected from the Yangtze river are lower than the Yellow river counterparts, however, the acute to xicity effects of Zn-spiked and Ni-spiked overlying water samples collected from the Yangtze river are higher than the Yellow river counterparts. As for the heavy metals-spiked sediments from the Yangtze river, the toxicity differences amo ng the four heavy metals on Daphnia magna are Cd, Cu, Zn, Pb(in descending order).

Key words: water column, interstitial waters, sediment, heavy metal