湘江入湖河段沉积物重金属污染及其Pb同位素地球化学示踪

湘江是我国重金属污染最严重的河流之一.本次工作利用等离子质谱(ICP-MS)和多接收同位素质谱(MC-ICP-MS)等技术,对湘江入湖河段沉积物进行了系统的重金属微量元素和Pb同位素分析.结果表明,湘江河床沉积物明显富集Bi、Sc、V、Mn、Ni、Cu、Zn、Pb、Cd、Sn、Sb等多种重金属微量元素,而湖盆沉积物重金...

Heavy metal contamination of inlet sediments of the Xiangjiang River: With Pb isotopic geochemical implications on metal sources

The Xiangjiang River is one of the rivers that were most seriously contaminated by heavy metals in China. The present study makes a systematic analysis of concentrations of trace metals and Pb isotopic composition of the sediments using ICP-MS and MC-ICP-MS techniques. The results show that the river sediments were significantly concentrated and enriched with heavy metals Bi, Sc, V, Mn, Ni, Cu, Zn, Pb, Cd, Sn and Sb. This metal enrichment may cause heavy metal contamination to the sediments. The heavy metal contamination was evaluated using the geo-accumulation index (Igeo). The results show that the river sediments were potentially contaminated by heavy metals Cd, Sb, Bi, Sn, Pb, Zn, U, Tl, Th, Mn and Cu, among which metal Cd arrives an extremely high degree of contamination, metals Sb, Bi, Sn and Pb strongly to moderately high degree of contamination, and metals Zn, U, Tl, Th, Mn and Cu moderately to slightly high degree of contamination. However, the lake sediments were not significantly contaminated by these metals except moderately high degree of contamination of metals Cd and Sb. Pb isotopic compositions of the sediments suggest that Pb in the river sediments is a mixture of multi-sources of Pb, which Pb contributed from both natural and anthropogenic processes. Pb of natural source may be the Pb contributed from weathering of granites distributed in upper river areas, and the anthropogenic Pb may mostly include Pb from different Pb-Zn ores distributed and exploited in the upper river areas and Pb from coal combustion in the lower river areas. The proportion of such anthropogenic Pb in the river sediments is about 80%. Pb in the lake sediments is mostly composed of anthropogenic Pb from Pb-Zn ores and coal combustion, and is less influenced by Pb from granite weathering taken place in upper river areas. It is deduced that the heavy metals Sc, Cd, Bi, Cu, Zn, Sn and Sb also are mixtures of natural and anthropogenic processes, like metal Pb. Therefore, the protection of heavy metal contamination for the region should be stressed on various industrial activities of mineral application of Pb-Zn metal ores in the watershed.