腐殖酸对汞的络合稳定特性及其环境学意义

Complex stability characteristics of humus with Hg and its environmental significance

对3种腐殖酸与Hg的络合稳定特性研究结果表明,腐殖酸与Hg的结合存在松结态与紧结态2种形态,其中富里酸主要以松结态为主,灰色胡敏酸与棕色胡敏酸则以紧结态占绝对优势。3种腐殖酸中富里酸对Hg的络合容量最高,但络合强度最低,其络合汞的环境活性将较高;灰色胡敏酸对Hg的络合容量最低,但络合稳定性最高,故所结合Hg的环境活性最弱。但受容量因素制约,灰色胡敏酸对Hg的络合稳定性将因Hg/灰色胡敏酸相对比例的升高而急剧下降。棕色胡敏酸对Hg络合特性介于富里酸与灰色胡敏酸之间。

The complex stability characteristics of three humus fractions with Hg were studied. The results show that Hg can either be strongly bound or weakly bound with the humus. Fulvic acid bound Hg is mainly in a weakly bound form, the grey humic and brown humic acid bound Hg are dominantly in a strongly bound form. Of the three humus fractions, fulvic acid has the largest complex capacity for Hg, but due to its lowest complex stability constant, fulvic acid bound Hg will have the highest environmental activity. The complex stability constant of grey humic acid for Hg is the highest so the Hg environmental activity is the lowest. But due to its limited complex capacity,the complex stability constant of grey humic acid with Hg will greatly drop with the increase of the mass ratio of Hg/grey humic acid. The complex characteristics of brown humic acid lies the medium between those of fulvic acid and grey humic acid.