腾冲火成岩分布地区流域重金属元素迁移富集规律

The Migration and Enrichment of Heavy Metals in Tengchong Watershed with Volcanic Rock Distribution

环境中的重金属污染一般与人类活动有关,但流域内自然来源的重金属影响也不容忽视。火成岩分布地区的地质高背景往往含有较高的过渡金属元素,其中以Cr、Ni、Cu含量较高,主要赋存在流域内的土壤和沉积物中,其对流域生态环境会造成持续性危害。为了解火成岩地区土壤和沉积物的重金属元素的迁移富集规律,为治理环境污染,保护人类生活环境提供一定意义的科学认识和参考依据。本研究以云南腾冲火成岩分布地区的龙川江和沙河两个流域为研究对象,系统采集基岩、土壤和沉积物样品进行研究。结果表明:两个流域内沉积物和土壤的矿物组成主要有石英、长石、黏土矿物及少量碳酸盐,风化过程中随长石的减少,黏土类矿物显著增加,重金属元素也随黏土矿物的增加而富集,Cr、Ni在土壤中富集,与总黏土矿物含量呈线性关系(Cr:R^(2)=0.3817;Ni:R^(2)=0.5797),沉积物中Cr、Ni、Zn、Pb含量与高岭石、云母和伊利石混层的含量呈线性关系(R^(2)=0.43~0.72)。重金属Cu、Zn、Pb在沉积物中富集,其传质系数在龙川江沉积物中与高岭石、云母和伊利石混层的含量呈线性关系(R^(2)=0.58~0.79)。黏土类矿物对重金属元素的富集和迁移具有重要作用。

While the impact of heavy metal pollution from human activities is significant,the impact of heavy metal pollution in the watershed should not be ignored.The high geological background of the igneous rock distribution area often contains high levels of transition metal elements,including Cr,Ni,and Cu,which are mainly found in soils and sediments in the watershed.These metals can cause persistent ecological harm to the watersheds.To understand the migration and enrichment patterns of heavy metal elements in the soils and sediments of igneous areas,we studied two watersheds,Longchuan River and Shahe River,in the distribution area of Tengchong igneous rocks in Yunnan Province.Systematic samplings of bedrock,soil and sediment were performed.The results showed that the mineral composition of sediments and soils in the both watersheds consisted mainly of quartz,feldspar,clay minerals,and a small amount of carbonate.With a decrease in feldspar during the weathering process,the clay minerals increased significantly,and the heavy metal elements were enriched with the increase of clay minerals.The contents of Cr and Ni were enriched in soils with a linear relationship with the total clay minerals(Cr:R^(2)=0.3817;Ni:R^(2)=0.5797).The contents of Cr,Ni,Zn,and Pb in sediments were linearly related to kaolinite and mica illite mixed layer(R^(2)=0.43-0.72).Heavy metals such as Cu,Zn,and Pb were enriched in sediments,and their mass transfer coefficients were linearly related to kaolinite,mica,and illite mixed layers in Longchuan River sediments(R^(2)=0.58-0.79).Clay minerals play an important role in the enrichment and transport of heavy metal elements.