Wavelength‐dependence of the photolysis of diiodomethane in seawater
Wavelength‐dependence of the photolysis of diiodomethane in seawater
复制标题
海水中二碘甲烷光解的波长依赖性
DOI：
10.1029/2005gl025424
复制
发表时间：
2006
影响因子：
5.2
通讯作者：
J. Plane
中科院分区：
文献类型：
--
作者：
M. Martino;P. Liss;J. Plane
在实验室中使用天然海水研究了CH 2 I2光解的波长依赖性。使用配备有单色器的1 kW白炽灯进行照射，并通过吹扫捕集气相色谱/质谱法测定卤代烃浓度。在290和365 nm之间测定CH 2 I2光解离的绝对量子产率，并且在0.27和0.39之间变化。我们的计算表明，在自然光照条件下，CH 2 I2的光解主要发生在300和350 nm之间。在海水中，计算出的CH 2 I2光解率随深度迅速下降，90%的衰减发生在顶部10-25米，这取决于水的透明度。一个简单的光化学箱模型的浅赤道混合层表明，大部分的CH 2 I2是光解之前到达海面，这种化合物是相对于底层水柱耗尽。
The wavelength‐dependence of CH2I2 photolysis was studied in the laboratory using natural seawater. Irradiations were carried out using a 1 kW Xe lamp equipped with a monochromator, and halocarbon concentrations were determined by purge‐and‐trap gas chromatography/mass spectrometry. The absolute quantum yields for CH2I2 photodissociation were determined between 290 and 365 nm, and varied between 0.27 and 0.39. Our calculations show that photolysis of CH2I2 under natural sunlight conditions occurs predominantly between 300 and 350 nm. In seawater, calculated CH2I2 photolysis rates decrease quickly with depth, with 90% attenuation occurring in the top 10–25 m depending on the water clarity. A simple photochemical box model of a shallow equatorial mixed layer showed that most of the CH2I2 is photolysed before reaching the sea surface, where this compound is depleted with respect to the underlying water column.