楚科奇海陆架重金属沉积研究

History of heavy metals recorded in the sediment of the Chukchi Sea,Arctic

采用Pb-Po法测定了楚科奇海陆架沉积物中210Pb的垂直剖面.应用双层模型研究210Pb分布,得到沉积速率(S)为0.145cm/a,沉积物堆积通量(FM)为78mg/(cm2.a),过剩210Pbex的沉积通量为6×10-3Bq/(cm2.a)[即0.36dpm/(cm2.a)].用中子活化分析方法和火焰原子吸收法分析测定了沉积物岩芯12个层段的重金属Cu、Pb、Zn、Cd、Cr、Co、Fe、Mn和V的含量,发现各层段之间重金属含量没有显著的区别.将本次分析结果和北冰洋其他一些陆架区的研究结果及页岩标准值相比较,发现楚科奇海沉积物中大部分重金属含量都相对较低.基于此可以推断,楚科奇海沉积物中重金属是源于地球化学过程的作用,没有表现出受到明显的人为重金属污染影响.

The vertical profile of ^210Pb in the sediment of the Chukchi Sea was determined by Pb-Po isotopic technique. By using a two-layer model to study the distribution of ^210Pb, the sedimentary rate （S） ,.accumulation flux of sediment （ FM） and sedimentary flux of excess 210 Pbex were estimated to be 0. 145 cm/a, 78 mg/（ cm^2·a） and 6 ×10^-3 Bq/（cm^2· a） [ 0.36dpm/（ cm^2· a） ], respectively. The changes in heavy metals （ Cu, Pb, Zn, Cd, Cr, Co, Fe,Mn and V） contents in 12 layers of the sedimentary core were analyzed and determined by instrumental neutron activation analysis （INAA） and flame atomic absorption method. It was found that the concentrations of the heavy metals in varied layers had no significant difference. Comparing the results with those of other Arctic shelf regions and the main value of the shale, the content of the heavy metals is lower. It was concluded that the source of heavy metals in the sediment of the Chukchi Sea was from natural geochemical process and no significant anthropogenie contribution was detected in the Chukchi Sea sediments.