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长江中游网湖沉积物重金属元素变化特征分析

ISSN号：1001-7410
期刊名称：《第四纪研究》
时间：0
分类：X524[环境科学与工程—环境工程] P618[天文地球—矿床学;天文地球—地质学]
作者机构：[1]中国科学院南京地理与湖泊研究所,南京210008, [2]中国科学院研究生院,北京100049, [3]宁波大学,宁波315211
相关基金：国家自然科学基金重点项目（批准号：40730529）资助

关键词：重金属, 环境变化, 人类活动, 污染评价, 网湖, heavy metal, environmental change, human activities, pollution evolution, Wanghu Lake

中文摘要：

在放射性核素137Cs和^210Pb精确计年的基础上，建立了长江中游网湖近代沉积物年代序列。通过对沉积物中金属元素含量和粒度的测定，结合相关的文献资料，分析了100多年来网湖沉积物中重金属元素的垂直分布特征、物源变化，以及自然因素和人类活动对其的影响，最后采用地累积指数法和潜在生态危害指数法进行了重金属污染评价。研究结果表明：20世纪50年代以前，人类活动对重金属元素沉积影响不大，重金属元素含量低于或接近参考的背景值，主要表现为自然沉积。其中1920—1950年间，流域高频率的洪灾使网湖沉积物中粘土物质减少，战乱和血吸虫病造咸阳新县工农业生产衰退，人口急剧下降，受此影响沉积物中重金属含量出现了一段低谷。50年代以后，随着人口的增长、经济的速猛发展，尤其是矿产开发和大规模的水利工程建设，流域水土流失加重，大量陆源物质进人湖泊，使Cu，Ti，Mn，Zn，Co，Fe和Pb含量增加。重金属污染评价结果表明：100多年来网湖总体上污染较轻，主要污染元素为Pb；Cu和Zn在60年代后出现轻度污染；Mn在沉积物表层出现轻度污染。目前，网湖RI=40．83，生态风险较小，但作为水生生物的养殖基地，中国重要的湿地保护区，其重金属污染问题应引起有关方面的关注，以防患于未然。

英文摘要：

Two sediment cores named WHA and WHD were drilled near the centre of the Wanghu Lake （29051° 29′54″N,115°20′- 115°25′E）in the area of the middle reaches of the Yangtze River. The depths of WHA and WHD cores were 42era and 72cm respectively. Both sediment cores were sliced into sections at a lcm interval in the field. Dating sequence of WHA core was established based on radioisotopes 137Cs and 210pb. The heavy metal contents in WHD core were measured with ICP-AES. The grain-size was analyzed by the particle-size analyzer in order to detect environmental changes and to understand the impact of natural processes and human activities on heavy metal abundance in Wanghu Lake＇s sediment over the past 100 years. The results show that the average sedimentation rate of the Wanghu Lake was about 0.56cm/a, and the bottom of the WHD core was dated around 1878A. D. According to vertical variation of heavy metal content, three stages were recognized：（1）Before 1920, all heavy metal（ Co, Cr, Cu, Fe, Mn, Ni, Pb, Ti, V, and Zn） contents were low or close to those of their natural geochemical background（ soil average heavy metal contents in Hubei Province） , reflecting that human activities at this stage had little influence on basin environment. During this period, the heavy metals of the sediment were mainly from natural soil. （2）From 1920 to 1950,most heavy metals have low accumulation rate except for Cu and Ti,which were probably resulted from the decline of economy and population of the Yangxin County caused by war and Schistosomiasis. Another possible reason is the frequent floods which were recorded by the increase of average grain-size of sediment during this period. （3）After 1950, along with the hydraulic engineering construction, the development of industry and agriculture, particularly mineral resources exploitation, contents of Pb, Cu, Ti, Mn, Zn, Co, and Fe in sediment have considerably elevated, indicating the human-made pollution increase and more terrestrial materials were tran

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