1998年特大洪水期长江口南汇嘴水域重金属元素的分布特征

The Distribution Character of Heavy Metal Elements over Nanhuizui Water Area of Yangtse Estuary in the Period of Catastrophic Flood, 1998

该文根据 1998年 9月长江口南汇嘴水域综合调查 ,探讨了该水域Cr、Mn、Fe、Cu、Zn、Cd、Pb七种重金属元素和A1的空间分布 ,通过计算和图表分析后认为 :水相中高含量重金属元素就平面分布而言 ,长江口口门区大于口内区及口外区而小于杭州湾北岸 ,垂向上则表现为随着水深的增大而增加的态势 ,而这种分布态势主要取决于水体中悬浮颗粒的浓度。低含量重金属元素的分布为口门区大于杭州湾北岸 ;固相重金属元素分布具有平面变化甚小、底层略小于表层的“准均一”性 ,这种“准均一”性主要由水域的悬浮颗粒同源于长江及其固有的吸附和解吸特性所致。进而经历史资料对比表明 :特大洪水对水相重金属元素有着显著的稀释作用 ,与常年同期资料相比 ,各种重金属元素均被稀释 6 0 %以上。

The paper deal with the distribution of seven hea vy metal elements (Cr, Mn, Fe, Cu, Zn, Cd, Pb) and Al over the Nanhuizui water are a of Yangtse Estuary based on the synthetical survey of this waters in Sep., 19 98. The results show that as plane distribution is concerned, the concentration of highly contented elements in water phase at the mouth is higher than that ins ide and outside of the mouth but lower than north bank of the Hangzhou Bay, whic h mostly depends on the concentration of suspended sediment. The concentration o f the lowly contented elements is higher in mouth area than in north bank of the Hangzhou Bay. On the other hand, their concentration all increase with water de pth. On the contrary, their distribution in solid phase is of quasihomogeneity w ith very little change in plane and on bottom layer being slightly less than on surface layer, which mainly result not only from the fact that the suspended sed iment of this area all come from the Yangtse River but also from their adsorptio n and anti-adsorption property. Furthermore, through contrast with historical ma terial, it shows that this catastrophic flood remarkably diluted these heavy met als in water phase, compared with the same period of normal years, they were all diluted more than six tenths. The distribution of the heavy metal elements of this waters has close relationsh ip with its suspended sediment distribution and estuarine front activities.