水溶性有机质对南京城郊菜地土壤Pb吸附解吸行为的影响

通过批处理试验研究了不同来源的水溶性有机质（DOM）对南京城郊菜地土壤铅（Pb）吸附解吸行为的影响。研究结果表明,DOM抑制了土壤对Pb的吸附,随着DOM浓度的增加,土壤对Pb的吸附量减少,当DOM体积从0增加到21 mL时,土壤对Pb的吸附量分别减少5.34%（鸡粪）、24.12%（牛粪）和0.35%（有机肥）。不同来源的DOM也影响土壤对Pb的吸附程度。当添加低浓度的DOM（添加体积小于6 mL）时,土壤对Pb的吸附量顺序为鸡粪DOM〈牛粪DOM≈有机肥DOM;当添加高浓度的DOM（添加体积大于6 mL）时,土壤对Pb的吸附量顺序为牛粪DOM〈鸡粪DOM〈有机肥DOM。反之亦然,DOM促进了土壤Pb的解吸,解吸量随添加DOM浓度的增大而增加。不同来源的DOM对土壤Pb解吸程度的影响也有所差异。对于低污染土壤,Pb的解吸量顺序为鸡粪DOM〉牛粪DOM〉有机肥DOM;对于高污染土壤,Pb的解吸量顺序为鸡粪DOM〉有机肥DOM〉牛粪DOM。Pb吸附动力学曲线揭示,添加DOM延缓了土壤Pb吸附平衡到达的时间。本研究表明,DOM增加了土壤Pb的环境风险。

Effect of Dissolved Organic Matter on Adsorption-desorption of Pb in the Vegetable Soil from a Suburb of Nanjing,China

The study investigated the effects of various dissolved organic matters（DOMs） extracted from chicken manure（CM）,cowdropping（CD） and commodity organic fertilizer（COF） on adsorption-desorption behaviors of lead（Pb） in vegetable soil from suburb of Nanjing City,Jiangsu Provice,China.The results showed that the amount of Pb adsorption to soil decreased with the increasing of DOMs added into the soil,which indicated that DOMs inhibited the adsorption of Pb to the soil.Pb adsorption amount decreased by 5.34% for CM,24.12% for CD and 0.35% for COF,when the volume of DOM added into the soil varied from 0 to 21 mL.When the volume of DOM added into the soil was less than 6 mL,Pb adsorption amount followed the order：CM-DOM CD-DOM ≈COF-DOM.When the volume of DOM was more than 6 mL,Pb adsorption amount followed the order：CD-DOM CM-DOMCOF-DOM.In consistence with the results of Pb adsorption in the presence of DOMs,the presence of DOM enhanced the desorption of Pb from the soil and Pb desorption amount increased with the increase of DOM concentration added into the soil.The amount of Pb desorption followed the orders：CM-DOM CD-DOMCOF-DOM in the soil with a low level of Pb,while CM-DOM COF-DOM CD-DOM in the soil with a high level of Pb.The kinetic curves of Pb adsorption in the study revealed that the adsorption equilibrium was delayed in the present of DOMs.The study indicated DOM increased the environmental risk of Pb in the vegetable soil.