影响钴在新疆荒漠区土壤中的形态分布因素研究

Influencing Factors of Cobalt Form Distribution in Desert Region,Xinjiang

[目的]考察不同pH、重金属钴初始浓度、陈化时间和离子强度对土壤中钴化学形态分布和生物有效性的影响。[方法]采取经典Tessier连续提取技术。[结果]随着处理土壤pH的升高,有机物结合态含量呈下降趋势,两者间有极显著的负相关(相关系数=0.800**,P<0.01),残渣态随pH升高呈上升趋势,生物有效性在pH 5时达到最大值。在研究初始钴浓度范围内,随着外源钴浓度的浓度的增加,土壤中钴的碳酸盐结合态和可交换态所占总钴的比例减小,生物有效性系数(K)呈明显的递减趋势,当钴浓度大于250mg/L时,K递减趋势较大;土壤环境离子强度在0.01 mol/L附近时,除残渣态外各形态钴在土壤中分布的比例达到最大值,当离子强度大于0.01 mol/L时,生物有效性系数降低,限制了土壤中钴的迁移性。在考察陈化时间内,土壤陈化10 d时,钴的生物有效性系数最大。[结论]各形态含量均随土壤介质pH、重金属钴初始浓度、陈化时间和离子强度有所变化,不同程度地影响着重金属钴在土壤中的富集状况。

[ Objective ] The research aimed to study the effects of different pH, concentration of initial cobalt, aging time and ionic strength on the form distributions and bioavailability rate of cobalt. [ Method ] The sequential fraction-Tessier technique and static adsorption method were adopted. [ Result] When pH was 5, bioavailability rate was increased obviously. At the range of research cobalt concentration （100 - 400 mg/L） , with the higher concentration of cobalt in soils, the less cobalt carbonate combined and exchangeable form proportion was less, and the bioavailability rate K showed an obvious decreasing trend. When ionic strength of soils was close to 0.01 tool/L, except for residual fraction, 6 forms of metal distribution ration reached the top value, when the ionic strength was greater than 0.01 mol/L, bioavailability rate decreased and limit the migration of cobalt in soil. In the study time of ageing under a certain concentration of cobalt, the bioavailability rate of cobalt was going to the largest when the sample aged for 10days. [ Conclusion]Difference factors have different impacts on chemical forms analysis with pH, concentration of initial cobalt, aging time and ionic strength in soils.