Degradation of Methyl Bromide and Methyl Chloride in the Oceans

对流层卤素作为平流层卤素和臭氧消耗的来源的重要性得到了很好的认识。根据《蒙特利尔议定书》和《清洁空气法》，工业生产寿命较长的氯氟化碳已被禁止，但从这种分子中恢复臭氧层的时间尺度约为几十年。因此，人们的注意力转向了寿命更短、对排放变化反应更快的卤代烃。在这个项目中，加州大学欧文分校的研究人员将继续他们正在进行的努力，以了解海洋在甲基溴(CH3Br)和甲基氯(CH3Cl)等低分子卤代烃的生物地球化学循环中所起的作用。在这一阶段的研究中，将继续进行海洋退化研究，以扩大先前对海洋的空间和时间覆盖范围，并将甲基氯(CH3Cl)包括在内。还将研究其他天然卤代化合物，如二溴甲烷(CH2Br2)、溴仿(CHBr3)和甲基碘(CH3I)在沿海海水中的降解。拟议的测量结果将订正海洋对大气中卤代烃的吸收、海洋可缓冲大气中卤代烃浓度的程度以及这些气体在表层海洋中的产生率的估计数。

ABSTRACTOCE-0221472The importance of tropospheric halocarbons as a source for stratospheric halogens and ozone depletion is well recognized. Industrial production of longer-lived CFC's have been banned under the Montreal Protocol and Clean Air Act, however the time scale for recovery of the ozone layer from such molecules is on the order of decades. As a result, attention has shifted towards the shorter-lived halocarbons that respond more rapidly to changes in emissions. In this project, researchers at the University of California at Irvine will continue their ongoing efforts to understand the role of the oceans in the biogeochemical cycling of low molecular-weight halocarbons, like methyl bromide (CH3Br) and methyl chloride (CH3Cl). In this phase of their research, oceanic degradation studies will be continued in order to extend prior spatial and temporal coverage of the oceans, and to include methyl chloride (CH3Cl). The degradation of other natural halogenated compounds such as dibromomethane (CH2Br2), bromoform (CHBr3), and methyl iodide (CH3I) will also be studied in coastal seawater. The proposed measurements will result in revised estimates for the uptake of atmospheric halocarbons by the oceans, the extent to which the oceans can buffer atmospheric halocarbon concentrations, and the production rate for these gases in the surface oceans.