卤素离子对溶解性黑碳光化学活性的影响  

Effect of halogen ions on photochemical activity of dissolved black carbon

作　　者：屠依娜 唐威 马艳琼 张志宇 田森林[1] 李英杰[1] TU Yi-na;TANG Wei;MA Yan-qiong;ZHANG Zhi-yu;TIAN Sen-lin;LI Ying-jie(Faculty of Environmental Science and Engineering,Kunming University of Science and Technology,Kunming 650500,China;Ecological Environment Monitoring Station of Anning Branch,Kunming Ecological Environmente Bureau,Anning 650300,China)

机构地区：[1]昆明理工大学环境科学与工程学院,云南昆明650500 [2]昆明市生态环境局安宁分局,生态环境监测站,云南安宁650300

出　　处：《中国环境科学》2022年第7期3362-3369,共8页China Environmental Science

基　　金：国家自然科学基金资助项目(21707058);云南省优秀青年基金资助项目(2019FI004)。

摘　　要：溶解性黑碳(DBC)是天然有机质的重要组分,但其在河口水环境中的光化学活性尚不清楚.为解决这个问题,以大豆秸秆溶解性黑碳为目标物,使用山梨酸能量转移同分异构方法研究河口水卤素离子浓度条件下激发三重态DBC(^(3)DBC^(*))的生成速率(F_(T))、淬灭速率(k_(s)’)、稳态浓度([T]_(ss))变化规律,并使用2,4,6-三甲基苯酚电子转移探针方法研究卤素离子对^(3)DBC^(*)电子转移过程的影响.结果表明,卤素离子及其离子强度作用对F_(T)无显著影响,但k_(s)’因离子强度和Br-重原子效应而减小,导致^(3)DBC^(*)的[T]_(ss)增加.高浓度DBC光化学实验证实离子强度作用引起DBC分子聚集,导致^(3)DBC^(*)的电荷转移过程减弱,从而抑制^(3)DBC^(*)的淬灭.山梨酸探针实验表明,卤素离子及其离子强度作用对^(3)DBC^(*)的能量转移无直接影响,主要是通过抑制^(3)DBC^(*)的淬灭,增加[T]_(ss).进一步研究发现卤素离子及其离子强度作用对低能态^(3)DBC^(*)(E_(T)<250kJ/mol)无显著影响,但抑制高能态^(3)DBC^(*)(E_(T)>250kJ/mol)的电子转移,且随卤素离子和离子强度的增加而愈发明显.Dissolved black carbon(DBC)is regarded as an important part of natural organic matter,however,its photochemical activity in the estuary is not clear.Here,the soybean straw DBC as the target,the changes in the formation rate(F_(T)),the loss rate constants(k_(s)’),and the steady-state concentrations([T]_(ss))of^(3)DBC^(*)in the presence of halogen ions in the estuary was explored by energy transfer isomerization of sorbic acid.The effects of halogen ions on^(3)DBC^(*)electron transfer were studied by 2,4,6-trimethylphenol method.The results showed that halogen ions and ionic strength did not affect F_(T),but k_(s)’was decreased due to ionic strength and heavy atom effect of Br,which increased[T]_(ss).The photochemical experiment of high concentration DBC confirmed that the ionic strength effect caused the aggregation of DBC molecules,which weakened the charge transfer of^(3)DBC^(*)and inhibited the quenching of^(3)DBC^(*).For energy transfer of^(3)DBC^(*),it was not directly affected by halogen ions and ionic strength,but by the increase of[T]_(ss).Moreover,it was further found that halogen ions and ionic strength had no significant effect on the low-energy(E_(T)<250kJ/mol)^(3)DBC^(*),but only on high-energy^(3)DBC^(*)and became obviously with the increase of the concentrations of halogen ions and ionic strength.

关 键 词：溶解性黑碳 河口水 光化学 离子强度 卤素离子 能量转移 电子转移 

分 类 号：X522[环境科学与工程—环境工程]