1939年以来鸭绿江中游重金属的沉积记录

Sedimentary records of heavy metals in the middle reaches of the Yalu River since 1939

本研究对采自鸭绿江中游水丰水库水深40 m处的柱状样进行了测年分析,同时检测了相应深度的粒度和重金属浓度。通过对多项指标的综合分析表明:1939年以来水丰水库8种重金属沉积记录具有4个阶段,分别对应1939—1951年受抗日战争和抗美援朝战争影响的阶段;1951—1979年经济缓慢恢复的阶段;1979—1994年经济快速发展及环境问题较突出的阶段;1994—2018年经济与生态环境保护同步发展的阶段。对各重金属的物源追踪的结果是:Cd和Hg主要是自然源;Ni、Pb、Cu、As受到农业活动影响,但仍以自然源为主;Cr主要来自加工业,Zn主要来自采矿业,均以人为活动占主导。用地累积指数法对重金属进行了污染评价:总体污染程度不高,只是Zn有轻微污染,但因沉积物与水体有物质交换,需引起重视。本研究填补了鸭绿江流域中、上游重金属污染研究的空白,也为人口相对稀少的边境区域的重金属沉积、溯源及人类活动的影响的研究提供参考。

A core sample was collected at the depth of 40 m in the middle reaches of the Yalu River.The radioactive dating by 210Pb and 137Cs,the vertical particle size and content of the heavy metals were measured after the sample dividing.The comprehensive results indicated that the deposition records of the 8 heavy metals in the Shuifeng Reservoir presented 4 stages characteristics since 1939.The first stage was related to Anti-Japanese War and Resist US Aggression and Aid Korea War from 1939 to 1951,the second stage to slow economic recovery from 1951 to 1979,the third stage to rapid economic development and obvious environmental problems from 1979 to 1994,and the fourth stage to the synchronous development of economic and ecological environment protection from 1994 to 2018.The results of the tracking provenance were that the Cd and Hg were mainly natural sources,the Ni,Pb,Cu,As were somewhat affected by the agricultural activities but still overall natural sources,the Cr was mainly from the processing industry and the Zn was mainly from the mining industry.The pollution degrees of the heavy metals were evaluated with the method of the index of geoaccumulation.The results were that the overall pollution level was not high,only with slight pollution in Zn.But attention should be paid to the Zn pollution because of the exchange of the sediments and the water.The finding could fill the gap of studying the heavy metal pollution in the middle and upper reaches of the Yalu River basin,and also provide an important reference for the judgment of heavy metal deposition,tracking provenance,and the influence of human activities in remote border areas.