Temperature and wavelength dependence of nitrite photolysis in frozen and aqueous solutions
Temperature and wavelength dependence of nitrite photolysis in frozen and aqueous solutions
复制标题
DOI：
10.1021/es062731q
复制
发表时间：
2007-05-15
影响因子：
11.4
通讯作者：
Anastasio, Cort
中科院分区：
文献类型：
--
作者：
Chu, Liang;Anastasio, Cort
虽然亚硝酸盐的光解作用是某些天然水体中羟基自由基（中心点OH）的重要来源，但其对溶液波长和温度的依赖性尚未得到充分的描述。此外，虽然有证据表明雪中会产生亚硝酸盐，但还没有对冰上的这种反应进行研究。为了解决这些差距，我们测量了冷冻和水溶液NO2-光解中心点OH的量子产率对波长和温度的依赖关系。从我们的溶液和冰的结果中，我们得出了一个描述NO2-光解中心点OH量子产率的主方程，它是温度（240-295 K）和照明波长（302-390 nm）的函数：Phi（NO2- -> OH中心点）(T,lambda) = (gamma(0) + a/(1 + exp((lambda - c)/b)))exp-(（e lambda + f)/R) x (1/295 -1 /T)）其中gamma(0) = 0.0204 +/- 0.0010, a = 0.0506 +/- 0.0022, b = 11.2 +/- 1.2, c = 332 +/- 1, e = 20.5 +/- 3.2, f = 7553 +/- 1204，不确定度代表1个标准误差，T为温度(K)， R为气体常数（8.314 J mol(-1) K-1）， λ为波长（nm）。利用这些结果，我们预测了阳光照射下极地雪粒上亚硝酸盐的准稳态浓度，并比较了亚硝酸盐、硝酸盐和过氧化氢的光解作用作为雪粒中心点OH来源的相对重要性。
While the photolysis of nitrite is an important source of hydroxyl radical (center dot OH) in some natural waters, its wavelength and temperature dependence have not been fully described in solution. In addition, there are no studies of this reaction on ice, although there is evidence of nitrite production in snow. To address these gaps, we have measured the wavelength and temperature dependence of the quantum yields of center dot OH from the photolysis of frozen and aqueous NO2-. From our solution and ice results, we derive a master equation that describes the center dot OH quantum yield from NO2- photolysis as a function of both temperature (240-295 K) and illumination wavelength (302-390 nm): Phi(NO2- -> OH center dot)(T,lambda) = (gamma(0) + a/(1 + exp((lambda - c)/b)))exp-(((e lambda + f)/R) x (1/295 - 1/T)) where gamma(0) = 0.0204 +/- 0.0010, a = 0.0506 +/- 0.0022, b = 11.2 +/- 1.2, c = 332 +/- 1, e = 20.5 +/- 3.2, f = 7553 +/- 1204, uncertainties represent 1 standard error, T is the temperature (K), R is the gas constant (8.314 J mol(-1) K-1), and lambda is the wavelength (nm). Using these results we predict the pseudo-steady-state concentrations of nitrite on sunlit polar snow grains and compare the relative importance of the photolysis of nitrite, nitrate, and hydrogen peroxide as sources of snow-grain center dot OH.