Microbial alteration of stable nitrogen and carbon isotopic compositions of organic matter

OLR (1985) 32 (12)

C. Chemical Oceanography

Vries van Heystplantsoen 2, 2628 RZ Delft, Netherlands. 85:7031 Kvenvolden, K.A., G.E. Claypool, C.N. Threlkeld and E.D. Sloan, 1984. Geochemistry of a naturally occurring massive marine gas hydrate. Org. Geochem., 6:703-713. A massive gas hydrate was unexpectedly recovered in upper slope sediment of the Middle America Trench offshore of Guatemala. The core contained only 5-7% sediment, the remainder being the solid hydrate composed of gas and water. The gas evolved during hydrate decomposition was 99.4% methane, ~0.2% ethane, and ~0.4% CO 2. Hydrocarbons from propane to heptane were also present, but in concentrations of less than 100 ppm. Formation probably involved the following processes: (1) upward migration of gas and its accumulation where conditions favored the growth of gas hydrates, (2) continued, unusually rapid biological generation of methane, and (3) release of gas from water solution as pressure decreased due to sea level lowering and tectonic uplift. USGS, Menlo Park, CA 94025, USA. 85:7032 Lee, Cindy and B.L. Olson, 1984. Dissolved, exchangeable and bound aliphatic amines in marine sediments: initial results. Org. Geochem., 6:259263. Marine sediments from the coast of Massachusetts and from the Pacific margin of Mexico were analyzed. Dimethyl and trimethyl amine were found in relatively large amounts in interstitial waters and bound within the sediments. Similarities between amine and ammonia behavior suggest that the amines are also a product of the decomposition of organic nitrogen compounds. Amines are more enriched in anoxic sediments compared to oxygenated sediments than would be expected from relative carbon and nitrogen contents. Dept. of Chem., WHOI, Woods Hole, MA 02543, USA. 85:7033 Lindeboom, H.J., H.A.J. De Klerk and A.J.J. Sandee, 1984. Mineralization of organic carbon on and in the sediment of Lake Grevelingen [Netherlands]. Neth. J. Sea Res., 18(3-4):492-510. Sediment mineralization was estimated for six stations of a saline lake by oxygen uptake measurements (bell jar method). Using a C/O 2 conversion factor of 0.29, a mineralization rate of 330 g m -2 a was calculated. Processes affecting this rate were examined in laboratory and field experiments with the following results: a macroflora and fauna

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contribution of 70 and 95 g m 2 a ~, respectively, good correlation between mineralization and temperature, and a major influence on oxygen uptake by bioturbation. North Sea Directorate, P.O. Box 5807, 2280 HV Rijswijk, Netherlands. (gsb) 85:7034 Livsey, A., A.G. Douglas and J. Connan, 1984. Diterpenoid hydrocarbons in sediments from an offshore (Labrador)well. Org. Geochem., 6:73-81. Robertson Res. Intl., Ltd., Ty'n-y-Coed. Llandudno, North Wales LL30 ISA, UK. 85:7035 Luan, Zuofeng, 1985. Characteristics of organic geochemistry of sediments in northern South Huanghai Sea. Oceanologia Lirnnol. sin., 16(1): 93-100. (In Chinese, English abstract.) Inst. of Oceanol., Acad. Sin., Qingdao, People's Republic of China. 85:7036 Macko, S.A. and M.L.F. Estep, 1984. Microbial alteration of stable nitrogen and carbon isotopic compositions of organic matter. Org. Geochem., 6:787-790. When Vibrio harveyi, a marine, aerobic, heterotrophic bacterium, was grown on different substrates, the bacteria fractionated the isotopes uniquely, related to the chemical nature of the substrate. Specifically, the C / N of the substrate, or the biosynthetic and metabolic pathways of these substances, or both, are important in determining the isotopic composition of the total organism. The results are important in determining isotope effects in respiration and biosynthesis. Moreover, microbes have the potential to alter to a highly variable extent the isotopic composition of organic matter entering the sedimentary record. Dept. of Earth Sci., Memorial Univ., St John's A1B 3X5, NF, Canada. 85:7037 Marlowe, I.T., S.C. Brassell, G. Eglinton and J.C. Green, 1984. Long chain unsaturated ketones and esters in living algae and marine sediments. Org. Geochem., 6:135-141. Series of C37-C39di- and triunsaturated ketones and methyl and ethyl esters of hexatriacontadienoic acid have been previously identified in marine sediments and the coccolithophorid Emiliania huxleyi. These compounds have now been found in four further species of the Isochrysidales (Prymnesiophyta) which are not known to bear coccoliths, suggesting that they are more widely distributed in living algae than previously thought. In addition, the ketones have been recognized in sediments of Eocene age