褐煤基材料对石灰性土壤铅镉生物有效性的影响

Effects of amendments derived from lignite on Pb, Cd bioavailability of lettuce in calcareous soil

为了解褐煤基材料对石灰性土壤铅、镉形态及其对生菜吸收铅、镉的影响,通过盆栽试验,将8种褐煤基材料分别与铅(Pb)、镉(Cd)污染土混合培养并栽培生菜共120 d,测定土壤DTPA(二乙烯三胺五乙酸)可提取态和生菜中铅、镉的吸收积累情况。结果如下:褐煤基腐植酸、去矿化褐煤、荷钙褐煤和褐煤基活性炭显著降低土壤中DTPA提取态铅含量,其3个施用量分别降低4.67%~7.97%、5.92%~11.46%、5.90%~11.80%和11.69%~26.43%,并随着材料施用量的增加,土壤中DTPA提取态铅含量逐渐减少;腐植酸树脂和腐植酸接枝共聚显著提高DTPA提取态铅含量,分别提高了5.82%~32.12%和2.55%~24.76%;硝化褐煤、磺化褐煤也有提高土壤中DTPA提取态铅含量的趋势;改性后比未改性褐煤显著影响土壤DTPA提取态铅含量,以活性炭处理降低最多,以树脂和接枝处理增加最多。褐煤、腐植酸、去矿化、活性炭和接枝降低土壤中DTPA提取态镉含量,活性炭和接枝作用达显著水平,显著降低的幅度分别是5.41%~13.51%和5.18%~27.70%;硝化、磺化、树脂显著提高土壤中DTPA提取态镉,增幅分别是7.92%~20.13%、5.74%~21.05%和21.30%~44.63%。褐煤、腐植酸、去矿化、荷钙、活性炭和接枝均能提高生菜地上部生物量,硝化、磺化和树脂则降低生菜生物量;地上部生物量与土壤中DTPA提取态铅、镉含量呈负相关。因此,褐煤基材料可显著地改变石灰性土壤中DTPA提取态铅、镉含量,显著影响生菜的生长量,且褐煤基材料对DTPA提取态铅和镉的影响存在差别。

The effect of amendments derived from lignite on DTPA-extractable lead（Pb）and cadmium（Cd）chemical speciation and its effect on lettuce growth in calcareous soil were examined by the pot experiment, eight kinds of lignite-based materials were mixed with Pb and Cd contaminated soil for 60 days, and then lettuce were grew for 60 days, soil DTPA-extractable Pb, Cd（two ethylene three amine five acetic acid）and the absorbed Pb and Cd in lettuce were determined.The results are as follows：humic acid,demineralization, calciumloaded and activated carbon significantly reduced DTPA-extractable Pb content by 4.67% -7.97%, 5.92% -11.46%, 5.90% -11.80% and11.69% -26.43% respectively, with the increasing of the materials added,the content of DTPA-extractable Pb decreased,resin and graft copolymerization significantly increased the DTPA-extractable Pb by 5.82%-32.12% and 2.55%-24.76%, nitrification and sulfonation also have the capacity of increasing the DTPA-extractable Pb in soil. The content of DTPA-extractable Pb in soil was significantly influenced by the modified lignites, which was decreased most by the activated carbon treatment, and increased most by resin and graft copolymerization.Lignite, humic acid, demineralization, activated carbon and graft copolymerization reduced DTPA-extractable Cd content in soil, activated carbon and graft significantly decrease it by 5.41%-13.51% and 5.18%-27.70%; nitration, sulfonation and resin significantly improved it by7.92%-20.13%, 5.74%-21.05% and 21.30%-44.63%. Lignite, humic acid, demineralization, calcium-loaded, activated carbon and grafting could increase the biomass of lettuce;nitration, sulfonation and resin decreased the biomass of lettuce. The relationship of biomass and soil DTPA-extractable Pb, Cd content was negatively correlated. Therefore, several lignite-based materials can significantly change Pb, Cd chemical specification in calcareous soil, significantly affect the growth of lettuce, and have different influence on DTPA-extractable Pb and Cd.