Photochemical Mineralization of Terrigenous DOC to Dissolved Inorganic Carbon in Ocean

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http://hdl.handle.net/10138/308195

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Aarnos , H , Gelinas , Y , Kasurinen , V , Gu , Y , Puupponen , V-M & Vähätalo , A V 2018 , ' Photochemical Mineralization of Terrigenous DOC to Dissolved Inorganic Carbon in Ocean ' , Global Biogeochemical Cycles , vol. 32 , no. 2 , pp. 250-266 . https://doi.org/10.1002/2017GB005698

Title: Photochemical Mineralization of Terrigenous DOC to Dissolved Inorganic Carbon in Ocean
Author: Aarnos, Hanna; Gelinas, Yves; Kasurinen, Ville; Gu, Yufei; Puupponen, Veli-Mikko; Vähätalo, Anssi V.
Contributor: University of Helsinki, Environmental Sciences
University of Helsinki, Department of Forest Sciences
University of Helsinki, University of Jyväskylä
Date: 2018-02
Language: eng
Number of pages: 17
Belongs to series: Global Biogeochemical Cycles
ISSN: 0886-6236
URI: http://hdl.handle.net/10138/308195
Abstract: When terrigenous dissolved organic carbon (tDOC) rich in chromophoric dissolved organic matter (tCDOM) enters the ocean, solar radiation mineralizes it partially into dissolved inorganic carbon (DIC). This study addresses the amount and the rates of DIC photoproduction from tDOC and the area of ocean required to photomineralize tDOC. We collected water samples from 10 major rivers, mixed them with artificial seawater, and irradiated them with simulated solar radiation to measure DIC photoproduction and the photobleaching of tCDOM. The linear relationship between DIC photoproduction and tCDOM photobleaching was used to estimate the amount of photoproduced DIC from the tCDOM fluxes of the study rivers. Solar radiation was estimated to mineralize 12.5 +/- 3.7 Tg C yr(-1) (10 rivers)(-1) or 18 +/- 8% of tDOC flux. The irradiation experiments also approximated typical apparent spectral quantum yields for DIC photoproduction (phi(lambda)) over the entire lifetime of the tCDOM. Based on phi(lambda)s and the local solar irradiances in river plumes, the annual areal DIC photoproduction rates from tDOC were calculated to range from 52 +/- 4 (Lena River) to 157 +/- 2 mmol C m(-2) yr(-1) (Mississippi River). When the amount of photoproduced DIC was divided by the areal rate, 9.6 +/- 2.5 x 10(6) km(2) of ocean was required for the photomineralization of tDOC from the study rivers. Extrapolation to the global tDOC flux yields 45 (31-58) Tg of photoproduced DIC per year in the river plumes that cover 34 (25-43) x 10(6) km(2) of the ocean.
Subject: APPARENT QUANTUM YIELD
NATURAL ORGANIC-MATTER
AMAZON RIVER PLUME
MICROBIAL DECOMPOSITION
LIGHT-ABSORPTION
ATLANTIC BIGHT
COASTAL OCEAN
WORLD RIVERS
GLOBAL OCEAN
HUMIC LAKE
1172 Environmental sciences
1171 Geosciences
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