花岗质岩浆岩土壤重金属地球化学特征及生态风险评价——以云南盈江旧城—姐冒地区为例

Geochemical characteristics and ecological risk assessment of heavy metals in granitic magmatic soil:A case study of the Jiucheng-Jiemao area in Yingjiang County,Yunnan Province

基于云南盈江旧城—姐冒地区238件岩石样品和4931件土壤样品,与其他地质单元对比,重点研究花岗质岩浆岩岩石和土壤中重金属地球化学特征和来源,并进行土壤重金属生态风险评价。结果表明:花岗质岩浆岩和高黎贡山岩群(Pt_(1)GL.)具有相似的物源或继承性,二者岩石中Pb含量相对上地壳偏高,而其他重金属含量较低;第四系(Q^(a))、芒棒组(N_(2)m)和高黎贡山岩群(Pt_(1)GL.)土壤重金属含量和变化特征与花岗质岩浆岩基本一致,且土壤重金属含量明显低于第四系(Q^(b))和关上组(D_(1)g)地层;结合岩性组分看,成土母质可能均以花岗质岩浆岩为主;花岗质岩浆岩和关上组(D_(1)g)土壤重金属含量主要受自然源影响,人为活动影响相对较小;地累积指数和潜在生态风险指数表明花岗质岩浆岩土壤重金属生态风险小,为清洁土壤;德宏州地区具有粮、糖、蔬菜等生产功能的农田土壤成土母质以花岗质岩浆岩为主,但相关工作程度低。通过对比研究认为,德宏州地区具有发展绿色、无公害食品产地的巨大潜力。

Based on 238 rock samples and 4,931 soil samples collected from the Jiucheng-Jiemao area of Yingjiang County,Yunnan Province,and compared with other geological units,this paper is focused on the study of geochemical characteristics and sources of heavy metals in granitic magmatic rocks and soils as well as ecological risk assessment of soil heavy metals.According to the results obtained,the granitic magmatic rocks and Gaoligongshan group(Pt_(1)GL.)rocks have similar provenances or inheritances.The Pb content in the two kinds of rocks is higher than that in the upper crust,while the content of other heavy metals is lower.The soil heavy metal content and change characteristics of the Quaternary(Q^(a)),Mangbang formation(N_(2)m)and Gaoligongshan group(Pt_(1)GL.)are basically the same as those of the granitic magmatic rock,which are significantly lower than the Quaternary(Q^(b))and Guanshang formation(D_(1)g).Combined with lithologic compositions,the soil parent materials of the Quaternary(Q^(a)),Mangbang formation(N_(2)m)and Gaoligongshan group(Pt_(1)GL.)may be mainly granitic magmatic rocks.The soil heavy metal values of the granitic magmatic rock and Guanshang formation(D_(1)g)are mainly affected by natural sources,and the influence of human activities is little.The geoaccumulation index and the potential ecological risk index indicate that the granitic magmatic soil has a low ecological risk of heavy metals and is a clean soil.The soil-forming parent materials of farmland with the production function of grain,sugar,vegetable,etc.in Dehong Prefecture are mainly granitic magmatic rock,but related study work is insufficient.Through comparative research,it is believed that Dehong Prefecture has great potential in developing green and pollution-free food production.