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利用Mapgis的空间分析功能和多元统计分析等方法,对清江流域4 180个水系沉积物样品中重金属元素Cd质量分数与区域出露地层的对应关系进行了研究,并结合区内部分地层岩石样品Cd的质量分数特征来揭示清江流域水系沉积物中Cd的物质来源。研究结果表明,高Cd沉积物(>0.3 mg/kg)样品采样点主要分布于二叠系和三叠系等地层,二叠系和三叠系的贡献因子分别为2 318.40和2 230.36(mg.km2)/kg,占所有地层贡献因子的65%。水系沉积物Cd高质量分数主要受二叠系和三叠系岩层的控制,同时还受到Cd自身地球化学性质和铁锰等氧化物吸附作用的影响。高Cd沉积物(>0.3 mg/kg)的元素共生组合特征与黑色岩系的元素富集程度相关,清江流域水系沉积物中的Cd主要来源于黑色岩系。石煤风化土壤的流失和石煤矿点开采过程中尾渣、废水的排放可能是清江流域水系沉积物Cd的重要点污染源。
Using the spatial analysis function of Mapgis and multivariate statistical analysis, the corresponding relationship between Cd concentration in heavy metal elements and exposed zones in 4 180 water system sediments of Qingjiang River Basin was studied. Combined with some samples of rock samples Mass fraction to reveal the material source of Cd in the sediments of Qingjiang River Basin. The results show that the samples of high Cd deposits (> 0.3 mg / kg) are mainly distributed in Permian and Triassic strata. The contribution factors of Permian and Triassic are respectively 2 318.40 and 2 230.36 (mg km2) / kg, accounting for 65% of all formation contribution factors. The mass fraction of Cd in aqueous sediments is mainly controlled by Permian and Triassic strata, as well as the geochemical properties of Cd and the adsorption of oxides such as Fe and Mn. The elemental symbiotic assemblage of high Cd deposits (> 0.3 mg / kg) is related to the degree of elemental enrichment in the black rock series. Cd in the sediments of the Qingjiang River basin mainly comes from the black rock series. The loss of weathered soil and the discharge of tailings and waste water during the coal mining process may be an important source of Cd pollution in the sediments of the Qingjiang River Basin.