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环境化学

Effects of fulvic acid on photolysis of polycyclic aromatic hydrocarbons in aqueous solution

摘要：以氙灯作为模拟光源,对水相中5种不同来源、不同浓度富里酸(FA)在5种PAHs光解中的作用进行了比较分析;并通过活性氧的捕获探讨了FA在PAHs光解中的作用.结果表明,不同来源FA的结构及其对PAHs光解的影响具有较高的一致性.在低浓度(1.25mg·L^-1)体系中FA对二氢苊、芴、菲的光解表现出不同程度的抑制作用,而对荧蒽和芘的光解则表现出一定的促进作用;随着体系中FA浓度的升高,其对PAHs的光解总体上呈抑制趋势.FA的存在一方面促进了单线态氧和羟基自由基的生成,强化了PAHs的活性氧光解进程;另一方面FA也可以参与PAHs分子的能量竞争.

Abstract：Effects of fulvic acids (FA) from 5 different sources on the photolysis of 5 polycyclic aromatic hydrocarbons (PAHs) in air-saturated pure water have been studied using a xenon lamp as light source. Similar effects were observed for all 5 FAs from different sources. When the FAconcentration was 1.25 mg·L^-1 in the systems,the photodegradation rates of acenaphthene,fluorine and phenanthrene were decreased while those of fluoranthene and pyrene were increased. However,with the increase of FA concentration in the systems,a decreasing trend of degradation rates was found for all 5 PAHs. The production of singlet oxygen and hydroxyl radical,which reacts with PAHs,was found to be enhanced in the presence of FA. However,FA competed with PAHs for photons. Therefore,the presence of FA has two opposite effects on the photodegradation of PAHs. It results in decreased PAH degradation rates under some conditions,but increased degradation rates under other conditions.