Photochemical Alteration of Dissolved Organic Sulfur from Sulfidic Porewater
Photochemical Alteration of Dissolved Organic Sulfur from Sulfidic Porewater
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DOI：
10.1021/acs.est.7b03713
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发表时间：
2017-12-19
影响因子：
11.4
通讯作者：
Dittmar, Thorsten
中科院分区：
文献类型：
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作者：
Gomez-Saez, Gonzalo V.;Pohlabeln, Anika M.;Dittmar, Thorsten
硫化物沉积物是溶解的有机硫（DOS）的海洋来源，但沉积DOS在好氧，阳光照射的水柱的命运是未知的。我们推测，从黑暗的沉积环境放电后的光降解的结果在DOS分子的转化和分解。为了验证这一假设，硫化物孔隙水从盐沼暴露于潜在的非生物转化的溶解有机物（DOM）的水柱。我们通过元素分析和分子通过超高分辨率质谱定量研究DOM转换。我们的研究表明，光反应性取决于DOM的元素组成，因为DOS分子式比那些没有硫的分子式更对光不稳定。在太阳照射之前，在硫化物孔隙水中鉴定的6451个分子式中，39%含有硫。照射29天后，DOS浓度从13 μ M减少到1 μ M，DOS分子式的数量减少了9%。比较孔隙水和海洋DOS分子式，太阳辐射增加的相似性，由于去除不存在于海洋中的光不稳定DOS公式。总之，硫化物沉积物中的DOS优先是光不稳定的，太阳辐射可能是控制孔隙水DOS稳定性和命运的潜在机制。
Sulfidic sediments are a source of dissolved organic sulfur (DOS) to the ocean but the fate of sedimentary DOS in the oxic, sunlit water column is unknown. We hypothesized that photodegradation after discharge from the dark sedimentary environment results in DOS molecular transformation and decomposition. To test this hypothesis, sulfidic porewater from a saltmarsh was exposed to potential abiotic transformations of dissolved organic matter (DOM) in the water column. We quantitatively investigated DOM transformations via elemental analysis and molecularly via ultrahigh-resolution mass spectrometry. Our study indicated that photoreactivity is dependent on DOM elemental composition as DOS molecular formulas were more photolabile than those without sulfur. Prior to solar irradiation, of the 6451 identified molecular formulas in sulfidic porewater, 39% contained sulfur. After 29 days of irradiation, the DOS concentration was depleted from 13 to 1 mu M, together with a 9% decrease in the number of DOS molecular formulas. Comparing porewater and oceanic DOS molecular formulas, solar irradiation increased the similarity due to the removal of photolabile DOS formulas not present in the ocean. In conclusion, DOS from sulfidic sediments is preferentially photolabile and solar irradiation can be a potential mechanism controlling the stability and fate of porewater DOS.