Chemistry of superoxide radical in seawater: CDOM associated sink of superoxide in coastal waters
Chemistry of superoxide radical in seawater: CDOM associated sink of superoxide in coastal waters
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DOI：
10.1021/es9905445
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发表时间：
2000-03-15
影响因子：
11.4
通讯作者：
Voelker, BM
中科院分区：
文献类型：
--
作者：
Goldstone, JV;Voelker, BM
有色溶解性有机物（CDOM）和腐殖物质含有非金属氧化还原循环组分，能够催化超氧（O-2（-））歧化。在一些沿海和切萨皮克湾水样中测量到的这种O-2（-）汇的一阶速率系数（k（伪））范围高达1.4 s（-1），与Cu物种催化歧化的幅度相当。在k（pseudo）与单个沿海水样的光吸收和盐度之间观察到显著的（r（2）= 0.73）相关性，表明与非海洋来源的CDOM有关。这种汇的活性不会因酸化或煮沸样品而改变，但会因光氧化作用而被去除，这表明它是一种有机化合物，但它既不是酶，也不可能由紧密结合的金属组成。从O-2（-）衰变形成的过氧化氢的化学计量表明，这个汇能够氧化还原循环催化O-2（-）的歧化。这种CDOM汇与前面描述的有机铜汇相结合，将在沿海沃茨中产生稳态超氧化物浓度，比单独从双分子歧化预测的浓度低100-1000倍。在各种腐殖酸和富里酸样品中也观察到催化O-2（-）衰变，可能是通过醌官能团发生的。虽然醌部分的存在下，腐殖酸和富里酸已被证明，有没有出现几个措施的醌含量和O-2（-）歧化率这些样品之间的良好的相关性。
Colored dissolved organic matter (CDOM) and humic substances contain a nonmetallic redox-cycling component capable of catalyzing superoxide (O-2(-)) dismutation. First-Order rate coefficients (k(pseudo)) measured for this O-2(-) sink in a number of coastal and Chesapeake Bay water samples range up to 1.4 s(-1), comparable in magnitude to catalyzed dismutation by Cu species. A significant (r(2) = 0.73) correlation is observed between k(pseudo) and the optical absorption and salinity of individual coastal water samples, suggesting an association with non-marine-derived CDOM. The activity of this sink is not changed by acidification or boiling of samples but is removed by photooxidation, indicating that it is an organic compound, but that it is neither enzymatic nor likely to consist of tightly bound metals. The stoichiometry of hydrogen peroxide formation from O-2(-) decay indicates that this sink is capable of a redox cycle catalyzing the dismutation of O-2(-) This CDOM sink combined with the organic copper sink previously described will produce a steady-state superoxide concentration in coastal waters that is 100-1000-fold lower than that predicted from bimolecular dismutation alone. Catalyzed O-2(-) decay was also observed in a variety of humic and fulvic acid samples, possibly occurring through quinone functionalities. Although the presence of quinone moieties in humic and fulvic acids has been demonstrated, there do not appear to be good correlations between several measures of quinone content and the O-2(-) dismutation rates of these samples.