低分子有机酸/盐对复合污染土壤中Pb、Zn、As有效性的影响  

Effects of Low Molecular-Weight Organic Acids/Salts on Availability of Lead,Zinc and Arsenic in Mixed Metal-Polluted Soil

作　　者：宋金凤[1] 杨金艳[1] 崔晓阳[1] 

机构地区：[1]东北林业大学,黑龙江哈尔滨150040

出　　处：《水土保持学报》2010年第4期108-112,118,共6页Journal of Soil and Water Conservation

基　　金：国家自然科学基金项目(30901145);中国博士后科学基金特别资助项目(200801277);中央高校基本科研业务费专项资金资助项目(DL09BA02)

摘　　要：模拟森林凋落物淋洗液中草酸/草酸盐和柠檬酸/柠檬酸盐浓度范围,研究了不同浓度草酸/草酸盐和柠檬酸/柠檬酸盐溶液对复合污染土壤中Pb、Zn、As有效性的影响和机制。研究表明,除较低浓度低分子有机酸和有机盐抑制As的释放外,所有浓度的草酸/草酸盐和柠檬酸/柠檬酸盐均促进A1层和B层污染土壤中Pb、Zn、As的活化释放,其中5.0 mmol/L时Pb释放作用最强,25.0 mmol/L时Zn和As活化效果最显著,且Pb和Zn的释放效果强于As。低分子有机盐对Pb、Zn、As的释放效果强于相应的低分子有机酸,即草酸盐强于草酸、柠檬酸盐强于柠檬酸,所以低分子有机酸/盐类物质促进重金属释放的主要机理在于低分子有机酸阴离子反应,H+在此过程中并不起主要作用。不同种类的低分子有机酸和有机盐对Pb、Zn、As有效性的影响也不同,表现为柠檬酸强于草酸,柠檬酸盐强于草酸盐,这与两种有机酸/有机盐的化学结构、离解常数及其和重金属形成络合物的稳定性大小有关。几种浸提剂对A1层土壤Pb、Zn、As的释放效应明显强于B层。By simulating oxalic and citric concentrations in forest litter leachates,a series of batch experiments were conducted to study the effects of low molecular-weight organic acids/salts on availability of lead,zinc and arsenic in mixed metal-polluted soils.It resulted that,except for organic acids/salts of low concentration decreasing As release,oxalic/oxalate and citric/citrate all stimulated Pb,Zn and As release of dark brown forest soil A1 and B horizons,of which 5.0 mmol/L concentration had the best capacity to Pb,and 25.0 mmol/L concentration to Zn and As.The release capacities of Pb and Zn were higher than those of As.Oxalate and citrate solutions respectively had much more higher soil-heavy metal-release efficiency than oxalic and citric solutions at the same concentration,therefore,the mechanisms for low molecular-weight organic acids/salts to solublize soil Pb,Zn and As should be dominated by the reactions of oxalic and citric anion,and not by H＋.Citric/citrate had higher release capacity to Pb,Zn and As than oxalic/oxalate the same in concentration,i.e.citrateoxalate,citricoxalic,and it was related with structures,dissociation constants and complexation capacities of the extractants.The release capacities of Pb,Zn and As by the same extractants of A1 horizon soil were higher than those of B horizon.

关 键 词：低分子有机酸 低分子有机盐 重金属 有效性 

分 类 号：S153.4[农业科学—土壤学]