The decoding of recent environmental history using the Lake Biwa sediments

分析了琵琶湖沉积物中环境污染的历史趋势。用~(210)Pb和~(137)Cs技术对沉积物的累积速率进行了估算。重金属铬、镍、铜、锌、砷、汞、铅被用作人为污染的制造者。沉积物中铬和镍的垂直分布呈恒定分布，而其他重金属在沉积物上层的浓度呈上升趋势。沉积物中重金属的污染可以用腹地的人为排放及其历史变化来解释。计算了自20世纪100年代以来盆地北部沉积物中重金属的总库存量，其中铜为465吨，锌为1050吨，汞为2.8吨，铅为284吨。此外，通过浓度相关矩阵和聚类分析对沉积物中主要元素的组成进行了分析，以阐明沉积物化学特征在地点之间的相关性。琵琶湖沉积物采样点之间的一般相关性可以通过沉积物物质在湖泊水流中输送过程中组分的物理和化学重新分布来解释。

The historical trends of the environmental pollutions recorded in the Lake Biwa sediments were analyzed. Estimations of the accumulation rates of the sediments were carried out by the 210Pb and the 137Cs techniques. The heavy metals, such as Cr, Ni, Cu, Zn, As, Hg, and Pb, were used as a maker of the anthropogenic pollutions. The vertical profiles of Cr and Ni in the sediments show constant distributions, whereas the concentrations of other heavy metals increased in the upper layer of the sediment. The contaminations of the heavy metals in the sediments could be explained by an anthropogenic discharge from the hinterland and its historical changes. Whole inventories of the heavy metals were calculated in the sediment of the north basin for 100 years from 1900s, at 465 tons for Cu, 1050 tons for Zn, 2.8 tons for Hg, and 284 tons for Pb. In addition, the composition of the major elements in the sediments was analyzed in concentration correlation matrix and cluster analysis in order to clarify the correlation of chemical characteristics of the sediments between the sites. The generic correlations among the sampling sites of the Lake Biwa sediments could be explained by the physical and chemical redistribution of the components during the processes in which the sedimentary materials are transported through the lacustrine water currents.