小秦岭金矿带农田土壤重金属的时空变异趋势及其意义

    Temporal and spatial variation of heavy metal contamination of farmland soil along the Xiaoqinling gold ore belt and its significance

    • 摘要: 研究农田土壤重金属累积的时空变异特征及定量化预测变异趋势,是探讨土壤重金属地球化学累积效应及预警方法的关键。收集整理小秦岭金矿区以往调研资料和陆续的动态监测数据,对比分析了近28年来研究区农田土壤重金属特征污染物Hg、Pb、Cd、Cu的时空变异特征和扩散速率,并利用年均增长量和总变化率2个参数,定量计算了研究区土壤Hg、Pb、Cd、Cu的累积速率,探讨其环境意义。分析表明,1985年至今研究区农田土壤重金属Hg、Pb、Cd含量平均值持续增长,Cu有所波动,但总体也呈增长趋势。在区域分布上,Hg、Pb、Cd基本以双桥河流域为浓集中心,随着时间的推移,污染范围均逐渐扩大,且向下游有加重的趋势,Cu和Pb的污染范围虽然也在扩大,但极重污染区正在减小甚至消失。

       

      Abstract: Characteristic spatial and temporal variability of heavy metals accumulation in soils and quantitative variation trend forecast constitute the key to investigating the cumulative effects of heavy metal geochemistry as well as the early warning methods. Based on collecting research and monitoring data of the past 28 years, the authors analyzed comparative distribution characteristics and temporal-spatial variation of characteristic pollutants Hg, Pb, Cd, Cu in farmland soils of the Xiaoqinling gold orefield and, by means of two parameters (the average annual growth of the amount and the total rate of change), calculated quantitatively the accumulation rate of characteristic pollutants of heavy metals in farmland soils in the study area, with a discussion on its environmental significance. The results show that, from 1985 up till now, the average content of Hg, Pb, Cd in farmland soils of this area has continually increased, Cu content fluctuated, but the extremely seriously polluted area decreased or even disappeared.

       

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