Photochemical Production of Methyl Halides with Guaiacol as the Precursor  

作　　者：YANG Fan ZHANG Yan WU Guanyu HE Zhen YANG Guipeng 

机构地区：[1]Frontiers Science Center for Deep Ocean Multispheres and Earth System,Key Laboratory of Marine Chemistry Theory and Technology,Ministry of Education,Ocean University of China,Qingdao 266100,China [2]Laboratory for Marine Ecology and Environmental Science,Qingdao Marine Science and Technology Center,Qingdao 266237,China [3]Institute of Marine Chemistry,Ocean University of China,Qingdao 266100,China

出　　处：《Journal of Ocean University of China》2024年第5期1275-1286,共12页中国海洋大学学报（英文版）

基　　金：funded by the Natural Science Foundation of Shandong Province,China(No.ZR2021MD034);the National Natural Science Foundation of China(No.42276039).

摘　　要：Methyl halides are crucial trace greenhouse gases in the atmosphere,playing a significant role in global climate change and the atmospheric environment.This study investigated the photochemical production of methyl halides in an artificial seawater system using guaiacol as a precursor through laboratory simulation experiments.The influences of various environmental factors,including illumination time,radiation wavebands,illumination intensity,concentrations of guaiacol and halide ions(X^(-)),Fe^(3+),salinity,dissolved oxygen(DO),and pH value on the photochemical production of methyl halides were examined.We demonstrated that increased illumination intensity and duration promote the photochemical production of methyl halides,with a notable enhancement under UV-B radiation.Guaiacol and halide ions were identified as key precursors,and their high concentrations facilitated the formation of methyl halides.Additionally,different types of halide ions exhibited a competitive relationship in producing methyl halides.The study found that an increase in pH inhibited the photochemical formation of CH_(3)I due to the reaction between OH^(-)and·CH_(3).Dissolved oxygen was found to inhibit the photochemical formation of CH3I while promoting the formation of CH_(3)Cl.Conversely,an appropriate concentration of Fe^(3+)enhanced the photochemical production of methyl halides.Field observations indicated a high photochemical production of methyl halides in the natural waters near Qingdao’s coastal area,likely due to the high concentration of dissolved organic matter(DOM),which supports photochemical reactions.Furthermore,the photochemical production of methyl halides in natural seawater was significantly higher than in dark conditions,underscoring the importance of illumination in promoting these photochemical processes in seawater.

关 键 词：methyl halides photochemical production dissolved organic matter GUAIACOL 

分 类 号：P73[天文地球—海洋科学] X51[环境科学与工程—环境工程]