Coastal measurements of short-lived reactive iodocarbons and bromocarbons at Roscoff, Brittany during the RHaMBLe campaign
Coastal measurements of short-lived reactive iodocarbons and bromocarbons at Roscoff, Brittany during the RHaMBLe campaign
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DOI：
10.5194/acp-9-8757-2009
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发表时间：
2009-01-01
影响因子：
6.3
通讯作者：
Carpenter, L. J.
中科院分区：
文献类型：
--
作者：
Jones, C. E.;Hornsby, K. E.;Carpenter, L. J.
2006年9月期间，通过对法国西北海岸布列塔尼罗斯科夫海洋边界层空气的GC/MS分析，确定了挥发性活性碘烃C2 H5 I、1-C3 H7 I、2-C3 H7 I、CH 2 ICl、CH 2 IBr、CH 2 I2和溴烃CH 2Br 2和CHBr 3的大气浓度。与其他沿海研究的比较表明，这些痕量气体的排放受到场地地形、海藻种群和分布以及风速和风向以及潮汐高度的强烈影响。浓度非常短暂的二卤甲烷CH 2 IBr和CH 2 I2特别显示潮汐依赖性的证据，在低潮时观察到较高的浓度在海藻床的最大曝光。我们还提出了有限数量的卤代烃测量表层海水和估计海-气通量的基础上，这些和同时进行的空气测量。CH 2Br 2和CHBr 3在空气和海水中都有很强的相关性，空气中的CH 2Br 2/CHBr 3比值为0.19，水中为0.06。光不稳定的二卤甲烷CH 2 I2、CH 2 IBr和CH 2 ICl的正午I原子通量总和约为5 × 10（3）分子cm（-3）s（-1），比基于同一地点的一致测量估计的I-2的I原子通量低几个数量级，这表明在Roscoff，主要的I原子前体是I-2，而不是活性碘碳。
Atmospheric concentrations of the volatile reactive iodocarbons C2H5I, 1-C3H7I, 2-C3H7I, CH2ICl, CH2IBr, CH2I2 and bromocarbons CH2Br2 and CHBr3 were determined by GC/MS analysis of marine boundary layer air at Roscoff, Brittany on the northwest coast of France during September 2006. Comparison with other coastal studies suggests that emissions of these trace gases are strongly influenced by site topography, seaweed populations and distribution, as well as wind speed and direction and tide height. Concentrations of the very short-lived dihalomethanes CH2IBr and CH2I2 in particular showed evidence of tidal dependence, with higher concentrations observed at low tide during maximum exposure of seaweed beds. We also present a limited number of halocarbon measurements in surface seawater and estimate sea-air fluxes based on these and simultaneous air measurements. CH2Br2 and CHBr3 were strongly correlated both in air and in seawater, with CH2Br2/CHBr3 ratios of 0.19 in air and 0.06 in water. The combined midday I atom flux from the photolabile diahlomethanes CH2I2, CH2IBr and CH2ICl of similar to 5x10(3) molecules cm(-3) s(-1) is several orders of magnitude lower than the estimated I atom flux from I-2 based on coinciding measurements at the same site, which indicates that at Roscoff the major I atom precursor was I-2 rather than reactive iodocarbons.