桂西北有色金属矿区周边桑园土壤污染评价及治理对策研究

Evaluation and Countermeasures for Soil Pollution in Mulberry Fields around the Non-Ferrous Metal Mining Area in Northwest Guangxi

摘要: 为了说明矿业生产和金属冶炼加工对有色金属矿区周边农作物生长及其品质的影响，以桂西北地区特色农作物桑树为研究对象，用电感耦合等离子体质谱仪测定了桑树根茎叶及其根部0 cm~20 cm表层土壤的重金属含量，分别用单因子污染指数、内梅罗综合污染指数和地累积指数对不同调查区域桑园样地土壤的污染状况进行评价。结果表明：大部分桑园调查样地土壤的锰、铜、锌、砷、硒、镉、铅含量超出了广西土壤背景值，最大超标倍数分别为187.58、10.42、40.80、87.69、12.76、270.08、37.24，其中镉超标最为严重；近邻矿区周边桑园土壤的重金属污染比较严重，非近邻矿区桑园土壤的重金属污染相对较轻，所有桑园调查样地土壤的内梅罗综合污染指数均达到重度以上；参照我国食品、饲料及中药材的重金属限量标准，部分桑树根茎叶的重金属含量已超标；矿区周边桑园土壤的重金属含量较高，但桑树的重金属含量比较低，重金属富集系数较小，说明其对重金属的耐受性较强。由此可见，桂西北有色金属矿区周边桑园土壤的重金属污染严重，栽种重金属低累积及耐性强的桑树品种，并辅以必要的农艺措施，或通过其他改良土壤措施，可以达到蚕桑产品质量安全及土地资源合理利用的目的。

Abstract: In order to explain the effects of mining production and metal smelting on the growth and quality of crops around non-ferrous metal mining areas, taking mulberry, a characteristic crop in northwest Guangxi as the research object, the heavy metal content in 0 cm~20 cm surface soil of mulberry roots, stems, leaves and roots was determined by inductively coupled plasma mass spectrometer. Single factor pollution index, Nemerow comprehensive pollution index and geo-accumulation index were used to evaluate the soil pollution status of mulberry field sample plots in different investigation areas. The results showed that the contents of manganese, copper, zinc, arsenic, selenium, cadmium and lead in the soil of most mulberry plots were higher than the background values in Guangxi, the maximum multiples of exceeding standard were 187.58, 10.42, 40.80, 87.69, 12.76, 270.08 and 37.24 respectively, and the most serious was cadmium. The heavy metal pollution in the soil of the mulberry field in the adjacent mining area is more serious than that in the non-adjacent mining area. The Nemerow Comprehensive Pollution Index of the soil in all the mulberry plots was over serious. According to the national standard of heavy metal limit for food, feed and Chinese medicinal materials, the heavy metal content of some mulberry roots, stems and leaves has exceeded the standard, and the heavy metal content of mulberry soil around the mining area is higher, however, the content of heavy metals in mulberry is relatively low and the enrichment coefficient of heavy metals is relatively small, which indicates that mulberry has a strong tolerance to heavy metals. Therefore, it can be seen that the heavy metal pollution in the mulberry soil around the non-ferrous metal mining area in northwest Guangxi is serious, and mulberry varieties with low accumulation of heavy metals and strong tolerance are planted, supplemented with necessary agronomic measures or other measures to improve the soil, the aim of quality safety of sericulture products and rational utilization of land resources can be achieved.