湘西北地区黑色岩系重金属高背景元素地球化学特征及迁移演化规律研究

Study on the Geochemical Characteristics of High-Background Heavy Metals in Black Rock Series and Their Migration and Evolution Laws in Northwest Hunan Region

摘要

湘西北地区黑色岩系含多种金属元素特别是重金属元素，对生态环境构成潜在威胁。为查明其对土壤、农作物的具体影响程度，本研究系统分析该岩系及其原生风化土壤重金属元素含量、富集特征，揭示黑色岩系重金属高背景层元素从岩石—原生风化土—稻田根系土—稻谷迁移演化规律。结果显示，黑色岩系重金属元素在表生风化过程中，均表现出在风化土中强烈富集的特征，但从原生风化土向稻田根系土转化过程中，多数元素总体呈下降趋势。不同元素不同层位降幅不同，这种差异是本底含量、表生环境和人为因素共同作用的结果；稻谷对重金属元素的吸收能力总体较低，但当稻田土壤重金属累积到一定程度，稻谷的吸收量将显著增加，进而导致稻谷重金属超标。本研究为阐明黑色岩系重金属高背景对农田土壤、农作物影响程度及污染防治提供了关键科学依据。

Abstract

The black rock series in the northwest region of Hunan Province contains various metal elements，especially heavy metal elements，poses a potential threat to the ecological environment．To determine the specific impact of these elements on the soil and crops，this study systematically analyzed the content and enrichment characteristics of heavy metal elements in the rock series and its original weathered soil，revealing the migration and evolution laws of heavy metal elements from the rock-original weathered soil-rice field root soil-rice grains in the high background layer of heavy metals of the black rock series． The results showed that during the surface weathering process，the heavy metal elements in the black rock series all exhibited a strong enrichment characteristic in the weathered soil．However，during the transformation from the original weathered soil to the rice field root soil，most elements generally showed a downward trend．The decline in different elements at different layers was different，and this difference was the result of the combined effects of background content，surface environment and human factors；the absorption capacity of rice for heavy metal elements was generally low，but when the heavy metal content in the rice field soil reached a certain level，the absorption amount of rice would significantly increase，thereby causing the rice to exceed the heavy metal limit．This study provides key scientific basis for clarifying the impact degree of the high background of heavy metals in the black rock series on farmland soil and crops and for pollution prevention and control．

关键词

重金属高背景 / 迁移演化 / 黑色岩系 / 湘西北地区

Key words

high background heavy metals / migration and evolution / black rock series / Northwestern Hunan Region

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基金资助

湖南省科技厅2024年部门联合基金项目(2024JJ8384)