贵州红枫湖溶解有机质不同分离组分的卤代活性研究

Chlorination Activity of Dissolved Organic Matter Fractions in Hongfeng Lake,Guizhou,China

饮用水使用氯化消毒产生的消毒副产物给人类健康带来了极大危害。利用XAD树脂与阴、阳离子交换树脂对贵州红枫湖水体中溶解有机质进行了富集分离,分成腐植酸、富里酸、疏水中性物质及亲水酸性、碱性及中性物质6种组分,比较了各组分在加氯消毒过程中卤代活性的大小及其三卤甲烷的生成情况,揭示了有机组分卤代活性与其结构之间的关系,并探讨了它们可能的来源,提出了相应的控制措施。结果表明,红枫湖水体溶解有机质以富里酸组分为主,占分离出总有机碳的56%。氯化消毒实验发现消毒副产物以三氯甲烷和一溴二氯甲烷为主,富里酸的卤代活性最强。结构分析显示各有机组分的卤代活性与紫外吸光系数和酚羟基含量之间具有显著相关性。6种分离组分的消毒副产物生成量中,富里酸是生成三卤甲烷的主要前驱物质,占消毒副产物总量的76%。有机组分的碳稳定同位素值与C/N比值表明,富里酸主要来自陆源有机物,其余组分兼有陆源和内源两种来源。因此,控制陆源污染是减少红枫湖消毒副产物前驱物的有效途径。

Disinfection by-products for using chlorine to disinfect in drinking water have been resulted in great threat for the health of human being.Lake Hongfeng,a man-made reservoir,serves as the principal drinking water resource for Guiyang City,Guizhou Province.With XAD resins and ion exchange resins,dissolved organic matter in Hongfeng Lake was extracted and separated into 6 fractions,i.e.fulvic acid,humic acid,hydrophobic neutrals,hydrophilic acids,hydrophilic bases and hydrophilic neutrals.Those fractions were characterized by elemental analysis,UV absorbance,and acid functional groups titration.The chlorination reactivity and total trihalomethanes were analyzed and compared,and their possible origins were also investigated.Results showed that fulvic acid was the main component among the 6 fractions,and accounted for 56% of the total extracted dissolved organic carbon.Higher Carbon content in hydrophobic fractions was observed than that in hydrophilic fractions.Chloroform and bromodichloromethane were the major chlorination by-products.Compared to other fractions,fulvic acid had higher chloroform reactivity.There was significant correlation between the chlorination activity of 6 different DOM fractions and their SUVA254 and hydroxybenzene content.Fulvic acid was the most important precursor of total trihalomethanes,and produce 76% of disinfection by-products.The range distribution of 13 C stable isotope and C/N ratio further suggested that fulvic acid was mainly derived from the terrestrial organic matter,while other fractions originated from both allochthonous and autochthonous sources.Therefore,controlling the input of allochthonous organic matter maybe an effective way of reducing the precursor of disinfection by-products in Hongfeng Lake.