基于APCS-MLR模型和UNMIX模型的农田土重金属源解析

Analysis of Heavy Metal Sources in Farmland Soil Downstream of Heap Leaching Field Based on APCS-MLR Model and UNMIX Model.

摘要:

为探明某堆浸场下游农田土壤重金属的空间分布特征、污染现状及来源，共采集0.2m和0.5m深度76个采样点的152个土壤样本，测定Cu、Zn、Cr等8种金属元素含量，运用单因子污染指数法和内梅罗污染指数法评价其污染水平，进而采用主成分分析、绝对主成分-多元线性回归（APCS-MLR）模型和UNMIX模型分别解析污染源，并使用地统计学分析法进行验证。结果表明，土壤中Cr、Pb、As和Hg的含量平均值超过云南省土壤背景值，其中，As含量高于背景值和筛选值的点位比例分别超过90%和70%。UNMIX模型解析结果显示重金属污染源主要有4个，源1为矿业开发和交通源，对As和Pb的贡献率分别为65%和56%；源2为农业活动源，对Cd的贡献率为91%；源3为自然母质源，对Cu、Zn、Cr、Ni的贡献率分别为63%、61%、62%和55%；源4为燃煤源，对Hg的贡献率为94%。APCS-MLR模型解析结果与UNMIX模型基本一致，但未单独识别出自然母质源。上述结果可为农田生态环境管理精准施策提供技术支撑，为矿山污染防治及改善采矿工艺流程提供理论依据。

关键词:重金属;分布特征;污染评价;源解析;堆浸场

Abstract:

In order to explore the spatial distribution characteristics， pollution status and sources of heavy metals in farmland soil downstream of a heap leaching field， 152 soil samples were collected from 76 sampling points at 0.2 m and 0.5 m depths， and the contents of 8 metal elements such as Cu， Zn and Cr were determined. The pollution level was evaluated by single factor pollution index method and Nemerow pollution index method， and then the pollution sources were analyzed by principal component analysis， absolute principal component-multiple linear regression （APCS-MLR） model and UNMIX model， and verified by geostatistical analysis. The results showed that the average contents of Cr， Pb， As and Hg in the soil exceeded the soil background values in Yunnan Province， and the proportion of As content higher than the background value and the screening value exceeded 90% and 70%， respectively. The results of UNMIX model analysis showed that there were four main sources of heavy metal pollution. Source 1 is the mining development and traffic source， which contributed 65% and 56% to As and Pb， respectively. Source 2 is the source of agricultural activities， and the contribution rate to Cd was 91%. Source 3 is the natural source， and the contribution rates of Cu， Zn， Cr and Ni were 63%， 61%， 62% and 55%， respectively. Source 4 is the coal-fired source， which contributes 94% to Hg. The analytical results of APCS-MLR model were basically consistent with those of UNMIX model， but the natural parent material source was not identified alone. The above results can provide technical support for the precise implementation of farmland ecological environment management， and provide theoretical basis for mine pollution prevention and improvement of mining process.

Key words:heavy metal;distribution characteristics;pollution assessment;source analyze;heap leaching field