期刊
MARINE CHEMISTRY
卷 122, 期 1-4, 页码 138-147出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.marchem.2010.06.003
关键词
Photochemistry; Suspended particulate matter; Organic carbon; Oxidation; Photo-Fenton
资金
- NSF Chemical Oceanography
- Petroleum Research Fund
- NASA
We investigated photoredox transformations of oxygen, carbon, peroxides, and iron that accompany photodissolution of suspended marine particulate organic carbon (POC), a sunlight-induced process that transfers POC to the dissolved organic carbon (DOC) pool. During 18- to 24-hour photodissolution experiments with POC of varying composition, about 0.28 mol of O-2 was consumed per mole POC photodissolved. Mean dissolved inorganic carbon (DIC) production was 6% of initial POC in suspended river delta sediments and 1% in algal membrane detritus. The mean O-2 loss:DIC production ratio was -1.3:1 in sediment suspensions, which slightly exceeds the typical range reported for DOC. The O-2 loss:DIC production ratio was -7.7:1 in suspensions of algal detritus, which implies significant oxygen incorporation into (oxygenation of) organic matter. Irradiated sediment suspensions rapidly achieved low, steady-state peroxide concentrations but rose more slowly with algal detritus. Elevated iron concentrations in the 0.7-8.0 mu m particle size fraction after 24 h of irradiation are consistent with photoredox cycling of metals and/or with physical disintegration of organic-mineral aggregates driven by organic matter dissolution. These oxidation and oxygenation results differ from analogous reactions previously found for marine DOC, and estimates of DIC production in particle-rich environments will require incorporation of POC-specific information. (C) 2010 Elsevier B.V. All rights reserved.
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