Dissolved organic matter composition drives the marine production of brominated very short-lived substances.
Brominated very short-lived substances (BrVSLS), such as bromoform, are important trace gases for stratospheric ozone chemistry. These naturally derived trace gases are formed via bromoperoxidase-mediated halogenation of dissolved organic matter (DOM) in seawater. Information on DOM type in relation to the observed BrVSLS concentrations in seawater, however, is scarce. We examined the sensitivity of BrVSLS production in relation to the presence of specific DOM moieties. A total of 28 model DOM compounds in artificial seawater were treated with vanadium bromoperoxidase (V-BrPO). Our results show a clear dependence of BrVSLS production on DOM type. In general, molecules that comprise a large fraction of the bulk DOM pool did not noticeably affect BrVSLS production. Only specific cell metabolites and humic acid appeared to significantly enhance BrVSLS production. Amino acids and lignin phenols suppressed enzyme-mediated BrVSLS production and may instead have formed halogenated nonvolatile molecules. Dibromomethane production was not observed in any experiments, suggesting it is not produced by the same pathway as the other BrVSLS. Our results suggest that regional differences in DOM composition may explain the observed BrVSLS concentration variability in the global ocean. Ultimately, BrVSLS production and concentrations are likely affected by DOM composition, reactivity, and cycling in the ocean.
‡Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States.
Yina
Y
Liu
Daniel C O
DC
Thornton
§Department of Geological Sciences, University of Florida, Gainesville, Florida 32611, United States.
Thomas S
TS
Bianchi
∥Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, 500 Pillsbury Drive SE, Minneapolis, Minnesota 55455, United States.
William A
WA
Arnold
§Department of Geological Sciences, University of Florida, Gainesville, Florida 32611, United States.
Michael R
MR
Shields
⊥South China Sea Marine Engineering and Environment Institution, Guangzhou, Guangdong 510310, China.
Jie
J
Chen
Shari A
SA
Yvon-Lewis
D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism; D054879:Halogenation; D006812:Humic Substances / Q000032:analysis; D006842:Hydrocarbons, Brominated / Q000737:chemistry / Q000378:metabolism; D008031:Lignin / Q000737:chemistry / Q000378:metabolism; D009930:Organic Chemicals / Q000737:chemistry*; D010544:Peroxidases / Q000737:chemistry; D012623:Seawater / Q000737:chemistry*; D022882:Trihalomethanes / Q000737:chemistry
D000596:Amino Acids; D006812:Humic Substances; D006842:Hydrocarbons, Brominated; D009930:Organic Chemicals; D022882:Trihalomethanes; D008031:Lignin; D010544:Peroxidases; C026195:bromide peroxidase; C015044:bromoform; C027947:methylene bromide