土法炼锌区土壤-白菜系统中重金属的化学调控研究

采用苗圃盆栽试验,用腐殖质、EDTA、不同量的石灰等对赫章土法炼锌区的污染土壤进行处理。测定了基质的化学特性、重金属的DTPA提取态含量,并观察了白菜生长特性及其对重金属累积特性。结果表明,施用石灰处理,土壤速效磷由0.5mg/kg增加到10 mg/kg,土壤中Pb、Zn和Cd的DTPA提取态分别降低了83.9%、23.1%和79.4%;白菜中Pb、Zn和Cd的含量分别减少97.2%、94.7%和89.4%;白菜生物量增加了5.97倍。土法炼锌区影响白菜生长主要土壤因子是pH值和速效磷,白菜中的Cd、Pb与土壤DTPA提取态的Cd、Pb呈显著正相关。在土法炼锌区重金属污染土壤中施加石灰是一种实用而有效的改良措施。

CONTROL OF HEAVY METALS IN THE SOIL-CHINESE CABBAGE SYSTEM BY USING ADDITIVES IN THE INDIGENOUS ZINC SMELTING AREA

Pot-experiments were carried out to study heavy metal accumulation in Chinese cabbage planted in the polluted soil from the indigenous zinc smelting area of Hezhang County. The potted soils were treated with addition of humus, EDTA and limestone, respectively. Chemical properties, DTPA-exactable concentrations of Pb, Zn, Cd of soil, Chinese cabbage growth and its accumulation for heavy metals were determined in each pot-experiment. The results showed that the available P of soil increased from 0.5 to 10 mg/kg, DTPA-available Pb, Zn and Cd of substrates dropped by 83.9%,23.1% and 79.4%, respectively, biomass in Chinese cabbage increased by 5.97 times, and Pb, Zn and Cd contents in Chinese cabbage dropped by 97. 2% ,94.7 % and 89.4%, respectively. It is shown that major constraints on the growth of Chinese cabbage in polluted soil were pH value and available phosphorus. The Pb and Cd contents of Chinese cabbage were positive to DTPA-exactable Pb and Cd in soil. Application of limestone was a practical and effective approach to remediate the polluted soil in the indigenous zinc smelting area.