腐殖酸对铊污染土壤中铊形态和分布的影响

The effect of humic acid on the species and distribution of thallium in polluted soil

选用云浮含铊硫铁矿周围冲积土壤为供试样品,在土样中投加不同比例腐殖酸,采用连续浸提法对比研究了外源腐殖酸对受铊污染土中的铊不同形态及活性的影响。结果表明:随腐殖酸投入比的加大,酸可交换态含量明显下降,Fe/Mn氧化物结合态反之,有机质结合态与Fe/Mn氧化物结合态雷同,残余态几乎无变化;腐殖酸对酸可交换态铊分配比率最高为13.6%～30.5%,分别是有机态铊和Fe/Mn氧化态铊的2.8～15.1倍和2.8～3.7倍。结果说明腐殖酸有降低冲积土壤上有害活动态铊的功能,其作用机制在于腐殖酸具备的络合(螯合)能力和胶体特性。研究确认,腐殖酸可作为土壤重金属污染修复的优质材料。

Different ratios of humic acid were added into the alluvial-contaminated soils sampled from Yunfu pyrite to determine its effects on the speciation and activity of thallium using successive extraction. The results showed that humic acid significantly de- creased the content of dissoluble thallium and remarkably increased the content of Fe ＋ MnOx and organic form thallium. However, the content of residual thallium appeared no variations after the addition of humic acid. The highest partition ratio （13.6%-30.5%） affected by humid acid was found for dissoluble thallium, being 2.8-15.1 times and 2.8~3.7 times higher than the organic thallium and Fe ＋ MnOx thallium, respectively. The results implied clearly that humic acid, under certain conditions, could effectively in- crease the resistance to bioavailability and decrease the toxicity of thallium in alluvial soils by chelation and colloid characteristics of humic acid itself. It was confirmed that humic acid was a potential and widely-used candidate for heavy metal contaminated soils remediation.