采集六叉河流域多水塘沉积物,利用沉积物年代学方法,建立未受扰动水塘沉积物年代序列,研究流域Cd累积的历史过程及其环境效应.结果表明,江淮地区近30 a来农业集约化的迅速发展、磷肥的大量施用导致Cd在水塘沉积物中大量累积.利用水塘沉积物反演的Cd时空分布特征可以将Cd输入历史分为2个阶段:第1阶段是20世纪80年代以前,流域没有或者只有轻度Cd污染;第2个阶段是20世纪80年代以后,农业活动的迅速集约化过程导致了水塘沉积物中Cd的快速累积,人为活动输入的Cd含量呈增加趋势.对沉积物中Cd的风险评价表明,Cd总量中有10%～30%为可交换态和碳酸盐结合态,多水塘沉积物存在中等程度的Cd暴露风险.%Sediments collected from a number of ponds in Liuchahe watershed in Yangtze-Huaihe region of China were analyzed with chronological method to set up chronosequence of the undisturbed sediments for the purpose of study g historical process of Cd accumulation and its environmental impact. Results show that the rapid development of intensive agriculture in the past 30 years in the region led to application of large volumes of phosphate fertilizers, which resulted in Cd accumulation in the pond sediments in large volumes. The tempo-spatial distribution characteristics of Cd reversed by using pond sediments may divide Cd input history into two phases: the first phase refers to the decades before the 1980s, when the watershed was not or just slightly polluted with Cd; and the second phase, the decades after the 1980s, when the rapid intensification of fanning activities has led to rapid accumulation of Cd in pond sediments and Cd input through human activities is on an increasing trend. The Cd risk assessment of the sediments indicates that about 10％ - 30％ of total Cd is exchangeable Cd or carbonate-bonded Cd. The Cd in the sediments of these ponds is subject to a moderate level of exposure risk.
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