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风化煤对农田土壤重金属汞的钝化修复
曾文號, 黄春燕, 李 真, 廖 洋, 马 骏, 赵仕林
四川师范大学化学与材料科学学院
摘要:
风化煤钝化修复土壤主要是其活性官能团与重金属发生络合、鳌合等一系列反应,进而降低重金属在土壤中的可迁移性和生物有效性,以达到修复土壤的目的。本文系统研究了风化煤对重金属汞(Hg)的吸附特性及其对Hg在土壤中径向迁移和生物可利用性的影响。结果显示:风化煤对酸碱有一定的缓冲作用,pH对Hg的平衡吸附量影响不大,最大吸附量为8.19 mg/g,该吸附为吸热反应。风化煤对Hg的吸附作用采用Freundlich方程描述较好,为多分子层吸附,吸附动力可用拟二级速率方程描述。土柱试验中风化煤用量为1、2、4、8 g时,淋溶液中Hg含量分别下降2.62、1.66、1.10、0.70 μg/g,风化煤的使用可以降低Hg从土壤向溶液的迁移。盆栽试验进一步验证了风化煤对土壤中Hg迁移的阻控作用,其中添加风化煤黄壤中移栽30 d和70 d收获的白菜叶中Hg含量较未添加风化煤黄壤中下降了0.14 μg/kg和0.09 μg/kg;添加风化煤和外源Hg黄壤中Hg含量是未添加风化煤黄壤的2.4倍,而收获的30.70 d小白菜叶中Hg含量前者分别为0.53、0.82μg/kg,后者分别为0.35、0.48μg/kg,理论上可认为前者较后者分别下降了0.31、0.33 g/kg。可见,风化煤实现了对土壤中Hg的吸附、钝化,减缓了其生物可利用性,是一种廉价高效的环境友好型钝化剂。
关键词:  风化煤  Hg  吸附特性  生物可利用性  钝化
DOI:10.13758/j.cnki.tr.2018.05.018
分类号:X53
基金项目:国家自然科学基金项目(51641209,41641010)、四川省科技厅支撑计划项目(2016NZ0053)和成都市科技惠民项目(2014-HM01-00205-SF,2014-HM01-00204-SF)资助。
Passivation Remediation of Hg in Farmland Soil by Weathered Coal
ZENG Wenhao, HUANG Chunyan, LI Zhen, LIAO Yang, MA Jun, ZHAO Shilin
College of Chemistry and Materials Science, Sichuan Normal University
Abstract:
Weathered coal can be used for passivation remediation of heavy metals in farmland soil because it can chelate heavy metals with its active functional groups and reduce the mobility and bioavailability of heavy metals in soil. This study studied Hg adsorption characteristics of weathered coal and the radial migration and bioavailability of Hg in soil. The results showed that pH had little effect on Hg adsorption capacity due to the buffering of weathered coal, the maximum adsorption capacity was 8.19 mg/g. Hg adsorption of weathered coal was endothermic reaction, could be described well by Freundlich equation while the adsorption kinetic could be described well by pseudo-second-order rate equation. Hg content in leaching solution was decreased by 2.62, 1.66, 1.10, 0.70 μg/g, respectively when added weathered coal was 1, 2, 4 and 8 g into soil column, indicating weathered coal could reduce Hg migration from soil to solution. Pot experiment further proved weathered coal could prevent Hg migration from soil to plant, compared with CK, Hg concentration in cabbage leaves decreased by 400.00 mg/g and 0.09 μg/g in treatment 1(gellow soil added weatherad coal) and decreased by 0.31μg/g and 0.33 μg/g in treatment 2(yellow soil added weathered coal and Hg) when the cabbage was planted after 30 days and 70 days. Generally, weathered coal, as an efficient, environment-friendly and cheap material, can absorb Hg in soil and prevent its migration from soil to plant without any secondary pollution, thus provides a new strategy of the remediation of heavy metal contaminated soil.
Key words:  Weathered coal  Mercury (Hg)  Adsorption characteristics  Bioavailability  Passivation

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