盐酸提取条件下土壤重金属元素的释放特征

Release Characteristics of Soil Heavy Metals under HCl Extraction

采用河南省黄淮海平原典型农田土壤样品,开展了不同浓度盐酸(1,0.1,0.001,0.000 01 mol/L)和振荡时间(2,24,48,96 h)的土壤重金属元素提取实验,分析了盐酸浓度和振荡时间等对土壤重金属元素释放的影响,探讨了不同提取条件下土壤重金属元素的释放效果及其影响因素。研究表明:土壤Cr、Cu、Ni、Zn和Pb采用1 mol/L盐酸振荡48 h时萃取率显著高于其他处理,其中Pb的萃取率最高,土壤As采用1 mol/L盐酸振荡2 h时萃取率最高,碱性土壤Cd采用0.1 mol/L盐酸振荡2 h时萃取率最高。在此基础上,根据1 mol/L盐酸振荡2 h的提取结果,采用统计分析方法分析了土壤重金属元素全量、理化性质以及土壤类型对土壤重金属元素释放的影响,结果表明:土壤Cr全量越高,Cr萃取率越高;土壤干密度越大,Pb萃取率越高;土壤pH值越低,土壤Ni萃取率越高,而土壤Pb正好相反;土壤有机质对重金属元素萃取率无统计上的显著影响;Cu、As、Pb在碱性土壤(黄河流域)萃取率相对较高,而Cr、Ni、Zn在酸性土壤(淮河流域)萃取率相对较高;土壤类型对重金属元素释放的影响表现为砂姜黑土Cr,水稻土Cu、Ni、Zn,潮土As、Pb的萃取率相对较高。

The samples were obtained from the typical cropland in Huanghuaihai Plain, Henan Province. Extraction experiments of soil heavy metals under different HCl concentration （1,0.1,0. 001 and 0. 00001 mol/L） and shaking time （2,24,48 and 96 h）were carried out to figure out the effects of HCl concentration and shaking time on the release of heavy metals. The extraction effect of the soil heavy metals and its factors were also analyzed. The results show that the extraction ratios of Cr,Cu,Ni,Zn and Pb by 1 mol/L HCl extraction for 48 h shaking were much higher than those in other treatments,and the extraction ratio of Pb was the highest among the heavy metals. The extraction ratio of As by 1 mol/L HCl extraction for 2 h shaking,of Cd from basic soil by 0.1 mol/L HCl extraction for 2h shaking were the highest. Based on the results above, statistical analysis was used to analyze the effects of total metal content, physical and chemical properties,soil types on the extraction ratios according to the extraction ratios by 1 mol/L HCl extraction for 2 h shaking. The results indicate that extraction ratio of Cr is higher when the total Cr content of the soil is higher, and extraction ratio of Pb is higher when the dry density of the soil is bigger. While the extraction ratio of Ni is higher when the soil pH is lower,but Pb is just on the opposite. The organic matter content of the soil has no statistically significant effect on the extraction ratio of the soil heavy metals ; while extraction ratios of Cu, As and Pb are higher in basic soil（Yellow River basin）, but extraction ratios of Cr,Ni and Zn are higher in acid soil and the extraction ratio of Cr in indicotic black soil,Cu,Ni and Zn in paddy soil, As and Pb in meadow soil are the highest.