盆栽蔬菜土壤中汞的形态变化

Transformation of Hg Forms in a Soil-Vegetable System

以四九黄菜芯作为供试蔬菜,采用盆栽试验和连续化学萃取法-氢化物原子吸收光谱法,研究了种植蔬菜前后土壤Hg形态分布特点及蔬菜生长对Hg形态变化的影响。结果表明,外源Hg进入土壤后,在种植蔬菜前后的土壤中均主要以残渣态形式存在,蔬菜的生长明显影响土壤中的Hg存在形态。种植蔬菜后的土壤Hg形态变化表现为水溶态和腐植酸络合态明显减少,而强有机质结合态显著增加,随着外源Hg量的增加,土壤Hg形态由残渣态、强有机质结合态向交换态和碳酸盐铁锰氧化态转化,Hg的生物活性增强,蔬菜的生物量下降。除强有机质结合态和残渣态外,土壤中各形态Hg含量和总Hg量与蔬菜根、茎叶中Hg含量呈显著正相关。

Transformation of Hg form in a soil-vegetable system during vegetable-growing period was studied by the methods of pot-culture experiment and sequential extraction-hydride atomic absorption spectrometry. Results showed that Hg in kale yard soil existed mainly in residue form and were influenced significantly by vegetable growth. The main changes of Hg form in kale yard soil were the significant decrease of water soluble and humic acids complexible Hg and the significant increase of organic substance-bound Hg. With increase of Hg introduced, the residue-bound and organic substance-bound Hg gradually transformed into exchangeable, carbonate-bound and Fe-Mn oxide-bound Hg, which resulted in the increase of Hg bioactivity and the decrease of vegetable biomass. Except organic substance-bound and residue-bound Hg, there were significant positive correlations between various Hg form, total Hg contents of kale yard soil and Hg contents in vegetable roots, stem and leaf.