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Photochemistry of Organic Iron(III) Complexing Ligands in Oceanic Systems
Author(s) -
Barbeau Katherine
Publication year - 2006
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.2006.tb09806.x
Subject(s) - chemistry , biogeochemical cycle , ligand (biochemistry) , photochemistry , seawater , redox , siderophore , environmental chemistry , metal , photodissociation , inorganic chemistry , organic chemistry , ecology , biochemistry , receptor , gene , biology
Iron is a limiting nutrient for primary production in marine systems, and photochemical processes play a significant role in the upper ocean biogeochemical cycling of this key element. In recent years, progress has been made toward understanding the role of biologically produced organic ligands in controlling the speciation and photochemical redox cycling of iron in ocean surface waters. Most (>99%) of the dissolved iron in seawater is now known to be associated with strong organic ligands. New data concerning the structure and photochemical reactivity of strong Fe(III) binding ligands (siderophores) produced by pelagic marine bacteria suggest that direct photolysis via ligand‐to‐metal charge transfer reactions may be an important mechanism for the production of reduced, biologically available iron (Fe[II]) in surface waters. Questions remain, however, about the importance of these processes relative to secondary photochemical reactions with photo‐chemically produced radical species, such as superoxide (O 2 ‐ ). The mechanism of superoxide‐mediated reduction of Fe(III) in the presence of strong Fe(III) organic ligands is also open to debate. This review highlights recent findings, including both model ligand studies and experimental/observational studies of the natural seawater ligand pool.