| 长江中游网湖沉积物重金属元素变化特征分析 |
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| 引用本文： | 史小丽,秦伯强.长江中游网湖沉积物重金属元素变化特征分析[J].第四纪研究,2009,29(1):135-143. |
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| 作者姓名： | 史小丽 秦伯强 |
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| 作者单位： | 1. 中国科学院南京地理与湖泊研究所,南京,210008;中国科学院研究生院,北京,100049;中国科学院研究生院,北京,100049;宁波大学,宁波,315211
2. 中国科学院南京地理与湖泊研究所,南京,210008 |
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| 基金项目： | 国家自然科学基金重点项目 |
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| 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，战乱和血吸虫病造成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，大量陆源物质进入湖泊，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。
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| 关 键 词： | 重金属 环境变化 人类活动 污染评价 网湖 |
ANALYSIS ON HEAVY METAL DISTRIBUTIONS IN CORE SEDIMENT FROM WANGHU LAKE IN THE MIDDLE REACHES OF THE YANGTZE RIVER |
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| Shi Xiaoli,Qin Boqiang.ANALYSIS ON HEAVY METAL DISTRIBUTIONS IN CORE SEDIMENT FROM WANGHU LAKE IN THE MIDDLE REACHES OF THE YANGTZE RIVER[J].Quaternary Sciences,2009,29(1):135-143. |
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| Authors: | Shi Xiaoli Qin Boqiang |
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| Institution: | Nanjing Institute of Geography and Limnology|Chinese Academy of Sciences|Nanjing210008； |Graduate University of Chinese Academy of Sciences|Beijing100049； |Ningbo University|Ningbo315211 |
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| Abstract: | Two sediment cores named WHA and WHD were drilled near the centre of the Wanghu Lake(29°51′～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 42cm and 72cm respectively. Both sediment cores were sliced into sections at a 1cm 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 Lakes sediment over the past 100 years. The results show that the average sedimentation rate of the Wanghu Lake was about 056cm/a，and the bottom of the WHD core was dated around 1878AD. 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 transported into the Wanghu Lake. The results of geo accumulation index and potential ecological risk index show that the pollutants were mainly distributed at the sediment surface and the dominant contaminants were Pb，Cu，Mn，and Zn. Basically there were no pollution of Co，Cr，Ni，Ti，V，and Fe. The risk index (RI) is 40.83，indicating a weak ecological risk. |
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| Keywords: | heavy metal environmental change human activities pollution evolution Wanghu Lake |
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