香根草及添加剂对汞污染土壤汞固定的现场试验

通过前期盆栽模拟试验发现,汞污染土壤种植香根草木屑和腐殖土或者添加木屑和腐殖土后再种植香根草都能极大抑制汞通过地表径流迁移,但是尚没有开展野外试验进行验证。因此为了进一步验证其效果,本研究在贵州万山汞矿区大水溪村汞污染农田建立了地表径流小区,现场研究了种植香根草及添加木屑和腐殖土后种植香根草对土壤汞固定的影响,研究结果显示:(1)在所有处理小区的地表径流中,颗粒态汞占总汞的96%以上,是汞迁移的最主要途径;(2)在汞污染土壤中种植香根草或者土壤中分别添加木屑或者腐殖土后再种植香根草,都能显著降低地表径流中颗粒态汞含量(46%~67%),进而减少土壤汞通过地表径流向周围环境迁移,且香根草与木屑或腐殖土结合效果更佳;(3)不同处理均降低了地表径流中可溶态汞(13%~31%)的含量。本研究能为汞矿区汞污染土壤修复提供一定理论支持和技术指导。

Stabilization of Mercury in Hg-polluted Soil by Growing vetiveria zizanioides with Additives-Results from a Field Study

The results from previous pot experiments showed that both the growth of Vetiveria zizanioides in Hg-contaminated soil and sawdust-added or humus soil in soil plus planting Vetiveria zizanioides can efficiently stabilize mercury in soil. However, no field demonstration work has been conducted to investigate the practical aspects of this technology. Therefore, a series of surface runoff plots were built in a Hg-contaminated farmland at Dashuixi Village in the Wanshan mercury mining area to investigate the growth of Vetiveria zizanioides and sawdust-added or humus soil in soil plus planting Vetiveria zizanioides to stabilize mercury in soil. The results showed that (1) particle Hg in the surface runoff, which accounts for more than 96% of the total Hg, was the dominant form of Hg transportation to the environment; (2) planting V. zizanioides in Hg-polluted soil, growing V. zizanioides with sawdust or humus soil, respectively, can effectively reduce the concentrations of particle Hg(46%~67%) in surface runoff, therefore reducing the transportation of Hg in soil to the ambient environment. Moreover, growing V. zizanioides with sawdust or humus soil, respectively had the better effect; (3) the concentrations of dissolved Hg in surface runoff was declined by 13%~31% in all treatments. The results from this study can give some theoretical and technique supports for remediating mercury contaminated soils in the mercury mining area.