溶解性有机物对冰相中蒽和芘光降解的影响

Effect of dissolved organic matter on the photodegradation of anthracene and pyrene in ice

以Suwannee River Fulvic Acid Standard II(SRFA)、Upper Mississippi River NOM(UMRN)、Elliott Soil Humic Acid Standard IV(ESHA)和Leonardite Humic Acid Standard(LHA) 4种溶解性有机物(Dissolved Organic Matter, DOM)为研究对象,利用125 W高压汞灯作为模拟光源进行室内模拟光解实验,考察了DOM对冰相中蒽和芘光降解的影响.其中,SRFA和UMRN是水源DOM,ESHA和LHA是陆源DOM.结果表明,蒽和芘在冰相中均可以发生直接光降解.4种DOM对冰相中蒽和芘光降解的影响行为并不相同,水源DOM对冰相中蒽和芘光降解的影响程度小于陆源DOM.DOM对冰相中蒽和芘光降解的抑制以光屏蔽效应为主.4种DOM对冰相中蒽和芘光降解均产生淬灭效应,但淬灭程度相异,DOM对蒽激发态的淬灭程度高于其对芘激发态的淬灭程度.与DOM共存条件下,冰相中芘的表观光解速率常数与DOM的SUVA值具有显著正相关性(p<0.01).

The effect of dissolved organic matter(DOM) on the photodegradation of anthracene and pyrene in ice was evaluated by means of simulated photodegradation experiments in laboratory in this study. Four DOM samples with different origins, including Suwannee River Fulvic Acid Standard II(SRFA), Upper Mississippi River NOM(UMRN), Elliott Soil Humic Acid Standard IV(ESHA) and Leonardite Humic Acid Standard(LHA), were taken as the research objects. SRFA and UMRN are aquatic originated DOM, while ESHA and LHA are errestrial DOM. A 125 W high-pressure mercury lamp was used as the simulated light source. The results show that both anthracene and pyrene underwent direct photolysis in ice. four DOM samples had different influence on the photodegradation of anthracene and pyrene in ice. The extent of influence of aquatic originated DOM on the photodegradation of anthracene and pyrene in ice was weaker than that of errestrial DOM. The inhibition of DOM on the photodegradation of anthracene and pyrene in ice was dominated by the quenching effect. four DOM with different origins had different quenching effects on the photodegradation of anthracene and pyrene in ice. DOM exhibited greater quenching effect on the excited state of anthracene than that of pyrene. The apparent photodegradation rate constant of pyrene with DOM present in ice had an significant positive correlation with SUVA values of DOM(p<0.01).