双台子河口重金属污染的沉积记录

Sedimentary record of heavy metal pollution in the Shuangtaizi Estuary

根据双台子河口沉积柱中微量金属的含量及沉积物的粒度参数,结合137Cs放射性比活度精确定年,研究了双台子河口的沉积速率和重金属的污染变化特征,并利用地累积指数法评价了重金属的污染程度。137Cs计年的结果表明,沉积柱的平均沉积速率为1.3cm/a。沉积物的粒径从底层向表层逐渐变细,反映了水动力条件的减弱。绝大多数重金属的含量基本上都是自底部向上逐渐增加。重金属元素与细粒沉积物(<63μm)均具有较好的正相关性,说明细粒物质对重金属具有较高的吸附能力。采用地累积指数对沉积柱中重金属元素的垂向变化进行了评价,发现除Cd元素外,大部分元素均未受到污染(Igeo<0)。推测Cd的污染可能主要与20世纪90年代起至今人类活动对双台子河口产生的影响逐渐增加有关。

According to the analysis of the grain size, content of heavy metals （Cu, Pb, Zn, Cr, Cd, V, Co and Ni） and ^137Cs dating in sediment core from the Shuangtaizi estuary, the sedimentary rate and pollution characteristic of heavy metals were investigated. The geo-accumulation index was used to assess the pollution degree of heavy metals. Average sedimentation rate was 1.3 cm/a. The concentrations of most of the heavy metals showed a gradually increasing trend from the bottom to the top of the core. Grain size increased with increasing depth, reflecting weaker hydraulic condition at the top sediment layer. Good correlations between heavy metals and finer particle material （〈63 μm） indicate excellent adsorption capability of fine grained mass on the heavy metals. Most of the heavy metals are unpolluted （Igeo〈0） except for Cd. It was presumed that Cd contamination might be related to gradually intensive anthropogenic activities on the estuary since early 1990s.