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    丹江口水库土壤-底积物镉生态地球化学风险评价

    Ecological geochemical risk assessment of cadmium in soil-sediment of Danjiangkou Reservoir

    • 摘要: 湖北省十堰—丹江口地区多目标地球化学调查由中国地质科学院地球物理地球化学勘查研究所2013—2015年组织实施,旨在查明测区元素地球化学分布和分配特征,开展国土资源环境评价与基础地质研究,为国家及地方经济社会科学可持续发展提供基础资料。调查发现了丹江口水库底积物及沿汉江土壤镉富集现象。为保护丹江口水源地及南水北调水质安全,系统研究了丹江口库区不同生态区土壤、底积物中镉含量特点,计算了镉含量背景值和富集因子,为水库镉污染防治和生态修复提供了依据。镉生态地球化学风险评价显示,调查的样点中,100%消落区土壤、100%汉江底积物,99.45%深层土壤和92.41%的表层土壤属于农用地镉污染风险低土壤。水库底积物样点中低、中、高潜在生态风险比例分别占15.52%、20.69%、63.79%。分析了土壤和底积物中镉含量与pH值、Corg、常量元素含量的关系;建议通过切断上游污染源,防止水土流失,防治土壤酸化,开展生态修复等措施来防治库区底积物的镉污染、降低其生态风险。

       

      Abstract: The multi-objective geochemical survey in Shiyan-Danjiangkou area of Hubei Province was organized by the Institute of Geophysical and Geochemical Exploration, Chinese Academy of Geological Sciences during 2013-2015. It aimed to determine the geochemical distribution characteristics of elements in the survey area, conduct land resource environmental assessment and basic geological research, and provide basic data for the sustainable development of national and local economic and social sciences. The investigation revealed the accumulation of cadmium in the bottom sediments of Danjiangkou Reservoir and soil along the Hanjiang River. In order to protect the water source area of Danjiangkou and the water quality and safety of the South-to-North Water Transfer Project, the characteristics of cadmium content in soil and bottom sediments in different ecological areas of Danjiangkou reservoir area were systematically studied, and the background value and enrichment coefficient of cadmium content were calculated, which provided information for reservoir cadmium pollution prevention and ecological restoration. The eco-geochemical risk assessment of cadmium show that 100% of the water-fluctuating zone soil, 100% Hanjiang bottom sediment, 99.45% deep soil and 92.14% top soil belong to the agricultural land with low risk of cadmium pollution. The proportions of low, medium, and high-potential ecological risks in reservoir sediment samples account for 15.52%, 20.69%, and 63.79%, respectively. Based on the analysis of the relationship between the content of cadmium in soil and bottom product and the content of pH, Corg, and major elements, it is recommended to cut off upstream pollution sources, prevent soil erosion, prevent soil acidification, and carry out ecological restoration measures to prevent cadmium pollution of bottom sediments in the reservoir area and reduce its ecological risks.

       

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