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2017
Kumar, A, Borgen M, Aluwihare LI, Fenical W.  2017.  Ozone-activated halogenation of mono- and dimethylbipyrrole in seawater. Environmental Science & Technology. 51:589-595.   10.1021/acs.est.6b03601   AbstractWebsite

Polyhalogenated N-methylbipyrroles of two different structure classes have been detected worldwide in over 100 environmental samples including seawater, bird eggs, fish, dolphin blubber, and in the breast milk of humans that consume seafood. These molecules are concentrated in the fatty tissues in comparable abundance to some of the most important anthropogenic contaminants, such as the halogenated flame-retardants and pesticides. Although the origin of these compounds is still unknown, we present evidence that the production of these materials can involve the direct ozone activated seawater halogenation of N-methylbipyrrole precursors. This observation shows that environmental polyhalogenated bipyrroles can be produced via an abiotic process, and implies that the ozone activated halogenation of a variety of natural and anthropogenic seawater organics may be a significant process occurring in surface ocean waters.

2002
Repeta, DJ, Quan TM, Aluwihare LI, Accardi AM.  2002.  Chemical characterization of high molecular weight dissolved organic matter in fresh and marine waters. Geochimica Et Cosmochimica Acta. 66:955-962.   10.1016/s0016-7037(01)00830-4   AbstractWebsite

The high molecular weight fraction of dissolved organic matter in a suite of takes, rivers, seawater, and marine sediment interstitial water samples was collected by ultrafiltration and characterized by molecular level and spectroscopic techniques. Proton nuclear magnetic resonance spectra of all samples show a high degree of similarity, with major contributions from carbohydrates, bound acetate, and lipids. Molecular level analyses of neutral sugars show seven monosaccharides, rhamnose, fucose, arabinose, xylose, mannose, glucose, and galactose, to be abundant, and to occur in comparable relative amounts in each sample. Previous studies have emphasized the distinctive composition of dissolved humic substances in fresh and marine waters, and have attributed these differences to sources and transformations of organic matter unique to each environment. In contrast we find a large fraction of freshwater high molecular weight dissolved organic matter (HMWDOM; > 1 kD) to be indistinguishable from marine HMWDOM in bulk and molecular-level chemical properties. Aquatic HMWDOM is similar in chemical composition to biologically derived acylated heteropolysaccharides isolated from marine algal cultures, suggesting a biological source for some fraction of persistent HMWDOM. High molecular weight DOC contributes 51 +/- 26% of the total DOC, and monosaccharides 18 +/- 8% of the total HMWDOC in our freshwater samples. These contributions are on average higher and more variable, but not significantly different than for surface seawater (30% and 16% respectively), Biogeochemical processes that produce, accumulate, and recycle DOM may therefore share important similarities and be broadly comparable across a range of environmental settings. Copyright (C) 2002 Elsevier Science Ltd.

Aluwihare, LI, Repeta DJ, Chen RF.  2002.  Chemical composition and cycling of dissolved organic matter in the Mid-Atlantic Bight. Deep-Sea Research Part Ii-Topical Studies in Oceanography. 49:4421-4437.   10.1016/s0967-0645(02)00124-8   AbstractWebsite

This study focuses on the chemical characterization of high molecular-weight dissolved organic matter (HMW DOM) isolated from the Middle Atlantic Bight in April 1994 and March 1996. Using proton nuclear magnetic resonance spectroscopy ((HNMR)-H-1) and monosaccharide analysis we compared both spatial and temporal variations in the chemical structure of HMW DOM across this region. Our analyses support the presence of at least two compositionally distinct components to HMW DOM. The major component is acyl polysaccharide (APS), a biopolymer rich in carbohydrates, acetate and lipid, accounting for between 50% and 80% of the total high molecular-weight dissolved organic carbon (HMW DOC) in surface samples. APS is most abundant in fully marine, surface-water samples, and is a product of autochthonous production. Organic matter with spectral properties characteristic of humic substances is the second major component of HMW DOM. Humic substances are most abundant (up to 49% of the total carbon) in samples collected from estuaries, near the coast, and in deep water, suggesting both marine and perhaps terrestrial sources. Radiocarbon analyses of neutral monosaccharides released by the hydrolysis of APS have similar and modern (average 71parts per thousand) Delta(14)C values. Radiocarbon data support our suggestion that these sugars occur as part of a common macromolecule, with an origin via recent biosynthesis. Preliminary radiocarbon data for total neutral monosaccharides isolated from APS at 300 and 750m show this fraction to be substantially enriched relative to total HMW DOC and DOC. The relatively enriched radiocarbon values of APS at depth suggest APS is rapidly transported into the deep ocean. (C) 2002 Elsevier Science Ltd. All rights reserved.