湖北省铜绿山矿区农业土壤重金属形态及生物有效性

以铜绿山矿区农业土壤为研究对象,采用BCR连续提取法提取并测定了土壤中Cu、Zn、Pb、Cd四种重金属的形态和含量,分析了重金属各形态、土壤p H和有机质之间的相关性;并对重金属分布特征和有效性进行了分析,探究土壤本身性质对矿区农业土壤重金属及其生物有效性的影响因子。结果表明:矿区农业土壤受到重金属不同程度的污染,重金属的污染程度大小为:CuZnPbCd;各重金属之间存在不同程度的相关性,Pb和Zn之间显著相关,二者可能属于同源污染物;四种重金属总量与土壤的p H和有机质不存在相关性;Pb与Cu、Zn和Cd有效态含量之间有显著相关性,表明矿区农业土壤中重金属Pb与Cu、Zn和Cd有效态含量之间相互促进、相互影响的作用较强;矿区农业土壤p H值与Pb_(可还原态)、Cd_(可还原态)、Cd_(弱酸提取态)、Cd_(可氧化态)之间均存在显著相关关系;有机质含量与Pb_(可还原态)、Pb_(残渣态)、Cu_(残渣态)、Cd_(弱酸提取态)、Cd_(可还原态)、Cd_(可氧化态)之间相关性显著,可见土壤的p H值、有机质都会对土壤中重金属的化学形态产生一定的影响;土壤中Pb、Cd的生物有效性主要受其全量、土壤p H和有机质的影响,而Zn和Cu受其全量、土壤p H和有机质的影响较小。

Speciation and Bioavailability of Heavy Metals in Agricultural Soil from the Tonglvshan Mining Area, Hubei Province

Samples of agricultural soil from Tonglvshan mining area were collected and treated with BCR procedure and four different solutions. Correlations between contents of heavy metals and soil properties were analyzed. Distribution character and the bioavailability of heavy metals(Cd, Cu, Zn, and Pb) were discussed with the purpose of finding impact factors. Results indicate that the soil has been polluted with different degrees by heavy metals from Tonglvshan mine. The pollution degrees of heavy metals are in the order of Cu > Zn > Pb > Cd. It exhibits significantly positive correlation between Pb and Zn, suggesting that the pollution of Pb and Zn is resulted from homologous pollutants. There is no correlation between the total contents of heavy metals(Cd, Cu, Zn, and Pb) and soil properties including pH and organic matter content. Contents of Cu, Zn and Cd existing as available fraction exhibit significantly positive correlations with total content of Pb. Contents of Pb and Cd exist as reducible fraction; Cd exists as weak acid soluble fraction and oxide fraction exhibits significantly positive correlation with pH. The contents of Pb and Cd exist as reducible fraction; Pb and Cu exist as residual fraction; Cd exists as weak acid soluble fraction and oxide fraction exhibits significantly positive correlation with organic matter, indicating that soil pH and organic matter have a certain impact on chemical speciation of heavy metals. Total contents of Pb and Cd, soil pH and organic matter have major impacts on bioavailability of Pb and Cd, while weak impacts on bioavailability of Zn and Cu.