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Contribution of structural recalcitrance to the formation of the deep oceanic dissolved organic carbon reservoir
Author(s) -
Wang Nannan,
Luo YaWei,
Polimene Luca,
Zhang Rui,
Zheng Qiang,
Cai Ruanhong,
Jiao Nianzhi
Publication year - 2018
Publication title -
environmental microbiology reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.229
H-Index - 69
ISSN - 1758-2229
DOI - 10.1111/1758-2229.12697
Subject(s) - dissolved organic carbon , deep sea , environmental chemistry , chemistry , carbon cycle , microbial biodegradation , dilution , degradation (telecommunications) , deep water , carbon fibers , ecology , environmental science , oceanography , biology , microorganism , ecosystem , geology , paleontology , bacteria , physics , telecommunications , computer science , thermodynamics , materials science , composite number , composite material
Summary The origin of the recalcitrant dissolved organic carbon (RDOC) reservoir in the deep ocean remains enigmatic. The structural recalcitrance hypothesis suggests that RDOC is formed by molecules that are chemically resistant to bacterial degradation. The dilution hypothesis claims that RDOC is formed from a large diversity of labile molecules that escape bacterial utilization due to their low concentrations, termed as RDOC c . To evaluate the relative contributions of these two mechanisms in determining the long‐term persistence of RDOC, we model the dynamics of both structurally recalcitrant DOC and RDOC c based on previously published data that describes deep oceanic DOC degradation experiments. Our results demonstrate that the majority of DOC (84.5 ± 2.2%) in the deep ocean is structurally recalcitrant. The intrinsically labile DOC (i.e., labile DOC that rapidly consumed and RDOC c ) accounts for a relatively small proportion and is consumed rapidly in the incubation experiments, in which 47.8 ± 3.2% of labile DOC and 21.9 ± 4.6% of RDOC c are consumed in 40 days. Our results suggest that the recalcitrance of RDOC is largely related to its chemical properties, whereas dilution plays a minor role in determining the persistence of deep‐ocean DOC.