Structure Elucidation and Characterization of Polychlorinated Biphenyl Carboxylic Acids as Major Constituents of Chromophoric Dissolved Organic Matter in Seawater

Abstract

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.

Electrospray and photoionization mass spectrometry for the characterization of organic matter in natural waters: a qualitative assessment

“…The source of chlorine in this sample is likely a residue from the HCl used to acidify the water before solid-phase (C 18 ) extraction of the dissolved organic matter, as dissolved chlorine concentrations in Lake Drummond are quite low (9 mg/L) relative to dissolved organic carbon concentrations (105 mg/L) (Johannesson et al 2004). Nevertheless, natural organo-chlorine species are well documented, and we cannot rule out the possibility that they are preexisting components of Lake Drummond NOM (Myneni 2002;Repeta et al 2004;Leri et al 2007;Teuten and Reddy 2007).…”

Effects of chloride ions on bleaching of azo dyes by Co2+/oxone regent: Kinetic analysis

“…This different result indicates the possible formation of new breakdown products like chlorinated aromatic compounds. Repeta et al [35] reported that chlorinated aromatic acids display strong absorption bands (240-400 nm) in the ultraviolet and near-ultraviolet and therefore mainly contribute to absorbance of chromophoric dissolved organic matter in seawater. Other studies proved the formation of chlorinated organic products (AOX) due to the radical chain reactions of chloride ion with hydroxyl radical [21], although their molecular structures were not well identified yet.…”

A marine sink for chlorine in natural organic matter

“…Cl, with the highest electron affinity of any element, has never been shown to participate in this process. Organochlorines are known in the ocean, but primarily as volatile compounds emitted to the atmosphere 6-8 , anthropogenic contaminants with various fates 11-13 , and trace compounds in microbes or dissolved organic matter 14,15 with no significant recognized fluxes.Both enzymatic and abiotic pathways have recently been shown to incorporate Br into particulate organic matter (POM) in sea water 16 . We reasoned that similar reactions can incorporate Cl into marine organic particulates.…”