Structure elucidation and characterization of polychlorinated biphenyl carboxylic acids as major constituents of chromophoric dissolved organic matter in seawater.
Chromophoric or colored dissolved organic matter (CDOM) is one of the principal light adsorbing components of seawater, particularly in the ultraviolet, where it attenuates over 90% of downwelling ultraviolet radiation. In highly productive coastal regions and throughout most of the global ocean, in situ biological production is the major source of CDOM. However, little is known about CDOM composition on the molecular level, and there are only a few reports that link CDOM composition to autochthonous biological sources. Here we report the isolation and characterization of CDOM components from one coastal and two open-ocean sites. Each sample contains a complex mixture of light absorbing (300-400 nm) components, including 2,4-dichlorobenzoic acid and a suite of novel, polychlorinated biphenyl carboxylic acids that closely resemble polychlorinated biphenyls (PCBs) of anthropogenic origin. However, the global inventory and isomer distribution of dissolved chlorinated aromatic acids suggest they are derived from in situ biological production rather than anthropogenic contaminants. These novel chlorinated aromatic acids account for a significant amount of CDOM adsorption in the ultraviolet.
Repeta
Daniel J
DJ
Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543-1543, USA. drepeta@whoi.edu
Hartman
Nicholas T
NT
John
Seth
S
Jones
A Daniel
AD
Goericke
Ralf
R
D000327:Adsorption; D001267:Atlantic Ocean; D002264:Carboxylic Acids / Q000032:analysis* / Q000737:chemistry; D002723:Chlorobenzoates / Q000032:analysis* / Q000737:chemistry; D006812:Humic Substances / Q000032:analysis; D015394:Molecular Structure; D010140:Pacific Ocean; D010777:Photochemistry; D011078:Polychlorinated Biphenyls / Q000032:analysis* / Q000737:chemistry; D012623:Seawater / Q000032:analysis*; D014466:Ultraviolet Rays
D002264:Carboxylic Acids; D002723:Chlorobenzoates; D006812:Humic Substances; C070735:2,4-dichlorobenzoic acid; D011078:Polychlorinated Biphenyls