| 洞庭湖表层沉积物营养盐和重金属污染特征及生态风险评价 |
| Characterization and Ecological Risk Assessment of Nutrient and Heavy Metal Pollution in the Surface Sediments of Dongting Lake |
| 投稿时间：2014-09-01 修订日期：2014-11-04 |
| DOI：10.15928/j.1674-3075.2015.02.005 |
| 中文关键词:营养盐 重金属 生态风险 洞庭湖 表层沉积物 |
| 英文关键词:nutrients heavy metals ecological risk Dongting Lake surface sediments |
| 基金项目: |
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| 中文摘要: |
| 为探究洞庭湖表层沉积物中营养盐和重金属的空间分布特征与生态风险，分别于2012年2月和2013年4月在东、南、西洞庭湖各取3个共计9个具有代表性样点的表层沉积物，测定其有机质（OM）、总氮（TN）、总磷（TP）、镉（Cd）、汞（Hg）、砷（As）、铅（Pb）和铬（Cr）的含量。结果表明，洞庭湖表层沉积物中OM、TN和TP的含量分别为1.48%～4.22%、382～2217 mg/kg和142～716 mg/kg，与国内其它湖泊（水库）相比，OM和TN含量处于中等水平，其内源负荷不容忽视；OM和TN的空间分布相似，表现为南洞庭湖区＞东洞庭湖区＞西洞庭湖区，TP表现为东洞庭湖区＞西洞庭湖区＞南洞庭湖区。洞庭湖表层沉积物中，Cd、Hg、As、Pb和Cr的含量分别为0.60～20.70 mg/kg、0.090～0.640 mg/kg、10.4～83.7 mg/kg、16.9～95.8 mg/kg和59.0～199.0 mg/kg，其中Cd和As超过土壤环境质量三级标准，是主要的重金属污染物；Cd和Hg的空间分布相似，表现为南洞庭湖区＞西洞庭湖区＞东洞庭湖区；As、Pb和Cr的空间分布相似，表现为南洞庭湖区＞东洞庭湖区＞西洞庭湖区。初步评价结果显示，除TP外，其余营养盐和重金属均具有引起较低生态风险的可能性，横岭湖和虞公庙的Cd、As和Cr以及洞庭湖出口的Cr具有引起较高生态风险的可能性；受Cd和As含量较高的影响，南洞庭湖区具有较高的生态风险。 |
| 英文摘要: |
| Pollutants are deposited in the sediments of lakes and reservoirs but, under certain circumstances, nutrients and heavy metals can be released into the overlying water and lead to secondary pollution of the water environment. Sediments directly reflect the pollution status of a water body. Dongting Lake, the second largest fresh water lake in China, is hydrologically connected with the middle reaches of the Yangtze River. Sedimentation of sand and mud and embankment construction has segmented the lake into three distinct water bodies: West Dongting Lake, South Dongting Lake and East Dongting Lake. The aim of this study was to explore the spatial distribution characteristics and ecological risk of nutrients and heavy metals in the surface sediments of Dongting Lake in order to better understand the endogenous loading of Dongting Lake and provide a reference and evidence needed to more effectively control eutrophication and heavy metal pollution. Nine representative sampling sites were selected in the Dongting Lake. Surface sediments were collected in triplicate at each site in February 2012 and April 2013, mixed and stored frozen at 4oC. The mixed samples were dried and detritus was removed. After grinding and sieving, the organic matter (OM), total nitrogen (TN), total phosphorus (TP), cadmium (Cd), mercury (Hg), arsenic (As), lead (Pb) and chromium (Cr) in the sediments were determined. The ranges of OM, TN and TP content in surface sediments were, respectively, 1.48%-4.22%, 382 mg/kg-2217 mg/kg and 142 mg/kg-716 mg/kg. Compared with other lakes (reservoirs) in China, the content of OM and TN in Dongting Lake were mid-range, so the endogenous load is too large to ignore. Spatially, OM and TN displayed similar distribution patterns in the three sections; South Dongting Lake > East Dongting Lake > West Dongting Lake. The spatial distribution of TP was East Dongting Lake > West Dongting Lake > South Dongting Lake. The ranges of Cd, Hg, As, Pb and Cr content in surface sediments were, respectively, 0.60-20.70mg/kg, 0.090-0.640mg/kg, 10.4-83.7mg/kg, 16.9-95.8mg/kg and 59.0-199.0 mg/kg. The contents of Cd and As exceeded the environment quality class Ⅲ standard for soils in China and are the main heavy metal pollutants in Dongting Lake. The average contents of Cd and Hg showed similar spatial patterns South Dongting Lake > West Dongting Lake > East Dongting Lake. The spatial distributions of As, Pb and Cr were the same: South Dongting Lake > East Dongting Lake > West Dongting Lake. In conclusion, except TP the nutrients and heavy metals all have the possibility to pose low ecological risk to the ecosystem in the Dongting Lake. While Cd, As and Cr in Henglinghu and Yugongmiao and Cr in the estuary of Dongting Lake pose serious ecological threats to the system. High concentrations of Cd and As in South Dongting Lake also pose a high ecological risk. |
| 张光贵.2015.洞庭湖表层沉积物营养盐和重金属污染特征及生态风险评价[J].水生态学杂志,36(2):25-31. |
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