【摘要】 溶解性有机质（DOM）在光辐射下可以吸收光能产生活性氧物质（Reactive oxygen species, ROS）,如单线态氧（¹O₂）,羟基自由基（HO·）及激发三线态DOM（³DOM^*）等,这些ROS对污染物的光化学反应起着重要的作用.本实验在254 nm紫外光辐射下,利用特征ROS探针化合物,探究4种不同来源土壤DOM光致产生ROS能力的差异.通过XAD-8树脂分组将2种不同来源DOM分成5个组分,进一步探究DOM结构对ROS生成的影响.研究发现,来源于黄褐土、潮土的DOM分别产生¹O₂、HO·的能力较强,而来源于黄褐土的富里酸及潮土的胡敏酸产生³DOM^*的能力较强,说明不同来源DOM在光辐射下产生ROS的能力不同.紫外光谱分析表明,分子量较大、腐殖化程度较高的腐殖酸产生ROS的能力较强,且富里酸与胡敏酸对ROS生成的影响存在差异.整体来看,2种腐殖酸的不同分组组分对ROS生成的影响趋势相似,水与乙醇组分所产生的影响非常小,低pH值组分对ROS生成的影响比高pH值大.结合红外光谱分析,研究发现,低pH值组分的腐殖酸羧基含量较高,脂肪族官能团含量低,含氧量高,可能具有较高的光化学活性,有利于ROS的生成.此外,2种腐殖酸不同组分对ROS生成的影响存在差异,说明DOM结构中官能团的可解离程度对ROS生成具有一定影响.更多还原

【Abstract】 Reactive oxygen species（ROS） photo-generated by dissolved organic matter（DOM） that absorbs light energy under radiation, such as singlet oxygen（¹O₂）, hydroxyl radical（HO·） and excited triplet states of DOM（³DOM^*）, play important roles in the photochemical reaction of pollutants. In this experiment, the difference in ROS formation by irradiated DOM with four different sources of soil was investigated by using special probe compounds under 254 nm UV radiation. According to the XAD-8 fractionation, the DOM from two different sources was divided into five components to further explore the influence of DOM structure on ROS formation. We found that DOM derived from yellow clunamon soil and fluvo-aquic soil had stronger ability to produce ¹O₂ and HO·, respectively; while the fulvic acid derived from yellow cinnamon soil and the humic acid from fluvo-aquic soil had strong ability to produce ³DOM^*. These results suggested that different sources of DOM had different abilities to produce ROS under light radiation. Ultraviolet spectrum analysis showed that the humic acid with higher molecular weight and higher degree of humification had stronger ability to produce ROS, and the effect between fulvic acid and humic acid on ROS formation was different. Overall, the effects of different components of the two humic acids on ROS formation were similar, the effects of water and ethanol components were negligible, and the low pH component had a greater effect on ROS formation than the high pH component. Combined with the analysis of infrared spectroscopy, we found that the low pH component had high content of carboxyl group and low content of the aliphatic functional group and, therefore, the content of oxygen was high, which had high photo-activity. In addition, there was a difference in the formation of ROS between the two components of humic acid, indicating that the dissociation degree of functional groups in DOM structure had a certain influence on ROS formation.更多还原