重金属污染土壤清洗导致几种营养元素流失的研究

Loss of Several Nutrient Elements in Heavy Metals Contaminated Soil Due to Soil Washing

通过HC l、柠檬酸、EDTA这3种提取剂对Pb、Cd、Cu、Zn污染土壤的浸提试验,研究了土壤清洗洗脱重金属的效果,并探讨了土壤清洗导致K、C a、M g、F e、M n这几种营养元素的流失和有效性的改变。试验结果表明,土壤清洗能有效地洗脱土壤中的Pb、Cd、Cu、Zn,同时也造成了土壤中K、C a、M g、F e、M n的流失,降低了其中部分营养元素的有效性。EDTA对重金属的洗脱能力大于HC l和柠檬酸。HC l浸提造成的K、C a、M g的流失量大于柠檬酸和EDTA,柠檬酸浸提造成的F e流失量大于HC l和EDTA,EDTA浸提造成的M n流失量大于HC l和柠檬酸。HC l和柠檬酸浸提降低了土壤K、C a、M g的有效性;EDTA浸提提高了土壤K的有效性,降低了土壤C a的有效性,在高浓度时(50 mm o l/L),EDTA显著地降低了土壤M g的有效性。HC l浸提导致土壤K的有效性下降比柠檬酸严重,高浓度的EDTA浸提导致土壤C a的有效性下降比HC l和柠檬酸严重。HC l、柠檬酸、EDTA浸提都能提高土壤中F e的有效性,且EDTA的效应大于其它2种萃取剂;在低浓度时,3种提取剂都能提高土壤中M n的有效性,且以柠檬酸的作用最为明显,当提取剂浓度增加时,M n的有效性有所回落。

A batch experiment of the heavy metals contaminated soil with HCl, citric acid and EDTA was conducted to investigate removal of Pb, Cd, Cu and Zn by soil washing, and to explore the effects of soil washing on nutrient elements in the heavy metals contaminated soil. The results showed that soil washing effectively removed heavy metals, and that, in the same time, soil washing resuked in the loss of K, Ca, Mg, Fe and Mn, and decreased the availabilities of some nutrient elements in the heavy metals contaminated soil. The removal power of EDTA on heavy metal was much better than that of HCl and citric acid. The loss of K, Ca, Mg due to extracting of HCl was more than citric acid and EDTA. The loss of Fe due to extracting of citric acid was more than HCl and EDTA. The loss of Mn due to extracting of EDTA was more than HCl and citric acid. The extracting of HCl and citric acid decreased availabilities of K, Ca, Mg in the soil. The extracting of EDTA increased availabilities of K, decreased availabilities of Ca, and, in the high concentration （50 mmol/L）, decreased the availabilities of Mg in the soil remarkably. The availabihties of Fe in the soil increased through extracting of three extractants, and the effect of EDTA was the most significant. In lower concentration, these 3 extractants could all increase the availabilities of Mn, and the effect of citric acid was the most significant. With increasing in the concentration of extractants, the availabilities of Mn decreased a little.