TY - JOUR
T1 - Identifying the sources and sinks of CDOM/FDOM across the mauritanian shelf and their potential role in the decomposition of superoxide (O2-)
AU - Heller, Maija I.
AU - Wuttig, Kathrin
AU - Croot, Peter L.
N1 - Funding Information:
MH's participation was financially supported by the German BMBF project SOPRAN III (FKZ 03F0611A and 03F0662A, PC co-PI) that forms part of the German contribution to SOLAS (Surface Ocean Lower Atmosphere Studies). Funding for the participation of KW was awarded to PC from the DFG (CR145/17-1). Research work at sea was funded through SFB754 (DFG), project B5 (PC). We sincerely thank the officers and crew of the RV Maria S. Merian and the chief scientist, O. Pfannkuche, for their help at sea. Special thanks are also due to P. Streu, A. Bleyer (both GEOMAR), T. Kalvelage and M. Holtappels (both MPI) for their ship based and laboratory analysis. This work is a contribution of the Collaborative Research Centre 754 "Climate-Biogeochemistry Interactions in the Tropical Ocean" (http://www.sfb754.de), which is supported by the Deutsche Forschungsgemeinschaft (DFG).
Publisher Copyright:
© 2016 Heller, Wuttig and Croot.
PY - 2016
Y1 - 2016
N2 - Superoxide (O2-) is a short lived reactive oxygen species (ROS) formed in seawater by photochemical or biological sources, it is important in the redox cycling of trace elements and organic matter in the ocean. The photoproduction of O2- is now thought to involve reactions between O2 and reactive reducing (radical) intermediates formed from dissolved organic matter (DOM) via intramolecular reactions between excited singlet state donors and ground-state acceptors (Zhang et al., 2012). In seawater the main pathways identified for the decomposition of O2- into H2O2 and O2, involve reactions with Cu, Mn, and DOM. In productive regions of the ocean, the reaction between DOM and O2- can be a significant sink for O2-. Thus, DOM is a key component of both the formation and decomposition of O2- and formation of H2O2. In the present work we examined the relationships between O2- decay rates and parameters associated with chromophoric dissolved organic matter (CDOM) and fluorescent dissolved organic matter (FDOM) by using the thermal O2- source SOTS-1. Filtered samples (0.2 μm) were run both in the presence, and absence, of the metal chelator diethylenetriaminepentaacetic acid (DTPA) to determine the contribution from DOM. Samples were collected along a transect across the continental shelf of the Mauritanian continental shelf during a period of upwelling. In this region we found that reactions with DOM, are a significant sink for O2- in the Mauritanian Upwelling, constituting on average 58 ± 13% of the O2- loss rates. Superoxide reactivity with organic matter showed no clear correlation with bulk CDOM or FDOM properties (as assessed by PARAFAC analysis) suggesting that future work should concentrate at the functional group level to clearly elucidate which molecular species are involved as bulk properties represent a wide spread of chemical moieties with different O2- reactivities. Analysis of FDOM parameters indicates that many of the markers used previously for terrestrial sources of DOM and FDOM are called into question as marine sources exist. In particular recent work (Rico et al., 2013) indicates that algal species may also produce syringic, vanillic, and cinnamic acids, which had previously been ascribed solely to terrestrial vegetation.
AB - Superoxide (O2-) is a short lived reactive oxygen species (ROS) formed in seawater by photochemical or biological sources, it is important in the redox cycling of trace elements and organic matter in the ocean. The photoproduction of O2- is now thought to involve reactions between O2 and reactive reducing (radical) intermediates formed from dissolved organic matter (DOM) via intramolecular reactions between excited singlet state donors and ground-state acceptors (Zhang et al., 2012). In seawater the main pathways identified for the decomposition of O2- into H2O2 and O2, involve reactions with Cu, Mn, and DOM. In productive regions of the ocean, the reaction between DOM and O2- can be a significant sink for O2-. Thus, DOM is a key component of both the formation and decomposition of O2- and formation of H2O2. In the present work we examined the relationships between O2- decay rates and parameters associated with chromophoric dissolved organic matter (CDOM) and fluorescent dissolved organic matter (FDOM) by using the thermal O2- source SOTS-1. Filtered samples (0.2 μm) were run both in the presence, and absence, of the metal chelator diethylenetriaminepentaacetic acid (DTPA) to determine the contribution from DOM. Samples were collected along a transect across the continental shelf of the Mauritanian continental shelf during a period of upwelling. In this region we found that reactions with DOM, are a significant sink for O2- in the Mauritanian Upwelling, constituting on average 58 ± 13% of the O2- loss rates. Superoxide reactivity with organic matter showed no clear correlation with bulk CDOM or FDOM properties (as assessed by PARAFAC analysis) suggesting that future work should concentrate at the functional group level to clearly elucidate which molecular species are involved as bulk properties represent a wide spread of chemical moieties with different O2- reactivities. Analysis of FDOM parameters indicates that many of the markers used previously for terrestrial sources of DOM and FDOM are called into question as marine sources exist. In particular recent work (Rico et al., 2013) indicates that algal species may also produce syringic, vanillic, and cinnamic acids, which had previously been ascribed solely to terrestrial vegetation.
KW - Atlantic Ocean
KW - Colored dissolved organic matter (CDOM)
KW - Excitation emission matrix fluorescence
KW - Fluorescence dissolved organic matter (FDOM)
KW - Hydrogen peroxide
KW - Parafac
KW - Reactive oxygen species
KW - Superoxide dismutase
UR - http://www.scopus.com/inward/record.url?scp=85008698311&partnerID=8YFLogxK
U2 - 10.3389/fmars.2016.00132
DO - 10.3389/fmars.2016.00132
M3 - Article
AN - SCOPUS:85008698311
VL - 3
JO - Frontiers in Marine Science
JF - Frontiers in Marine Science
SN - 2296-7745
IS - AUG
M1 - 132
ER -