藻源溶解性有机质对汞甲基化的影响

Influence of algal derived dissolved organic matter on mercury methylation in water

【目的】探究藻源溶解性有机质(DOM)各亚组分在不同腐解时间、不同汞(Hg^(2+))质量浓度下对水体中汞甲基化的影响。【方法】应用树脂串联技术分离藻体DOM的6种亚组分,利用室内培养方式进行Hg^(2+)的甲基化试验。【结果】藻类DOM主要由羟基、烃基和芳环C=C等官能团组成;未经腐解的DOM各亚组分中,疏水性有机组分对汞甲基化的影响高于亲水性有机组分;随腐解时间延长,DOM官能团逐渐减少,疏水性有机组分对汞甲基化的影响表现为先降低后升高;亲水性有机组分抑制汞甲基化。【结论】DOM相对含量的升高抑制了汞的甲基化,DOM降解后,释放出来的Hg^(2+)被微生物重新利用,甲基化程度加剧。

[Objective]To determine the effects of subcomponents of algae dissolved organic matter(DOM)on mercury methylation at different decomposition intervals and different Hg^(2+)concentrations.[Method]Six subcomponents of the DOM derived from the algae through a tandem connection of resin,and then conducted simulation experiments separately.[Result]Algae DOM was mainly composed of hydroxyl group,alkyl group and C=C of aromatic hydrocarbon,etc.Different subcomponents of DOM before decomposition,the influence of hydrophobic component on mercury methylation was significantly stronger than that of hydrophilic component.With the progress of algal decomposition,the relative content of functional groups was gradually decreasing while the influence of hydrophobic components on Hg methylation first weakened and then enhanced during the decomposition process and hydrophilic component can inhibit Hg methylation.[Conclusion]The increase in relative content of DOM results in the inhibition of Hg methylation.After the decomposition of DOM,the Hg^(2+)released got methylated by bacteria again,which helped promote the degree of methylation.