Ihnenfeld, Verena (2012) Methan-, DMS- und DMSP- Messungen während der SHIVA Sonne-Fahrt im November 2011 . (Bachelor thesis), Christian-Albrechts-Universität zu Kiel, Kiel, Germany, 49 pp.

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Abstract

The aim of this Bachelor Thesis was to investigate a possible relationship between methane and dimethylsulfoniopropionate (DMSP). For this purpose methane and dimethyl sulfide (DMS) and DMSP were measured in water samples, taken on the Shiva Sonne Cruise in the South China and the Sulu Sea. The reason is the methane oversaturation of the subsurface - layer with regard to the atmosphere. Methanogenesis, the only known synthesis of methane is strictly anaerobic and therefore another source of methane can not be excluded. There are hypotheses considering anoxic niches or intestinal tracts of fish to be sources of methane. Further on an antiproportional relationship between methane and DMSP was shown in the area of Storfjorden. The measured methane concentrations were between 2.09 - 17.26 nM and showed an oversaturation between 9 and 808 %. The analysis also showed that the methane content depends on the bottom depth. With a bottom depth of more than 2000 m, the methane content stayed below 4.38 nM. The DMS - and DMSP - concentrations are in a nanomolecular range. The measured depth profiles of methane showed a well mixed top layer, as well as an abrupt rise of methane in the subsurface - layer and a methane maximum in depths of 75 m or more. The DMSPd - measurements in various depths resulted in a depth profile which is volatile and showed multiple minima and maxima throughout the water column. The second depth profile is incomplete, because of the Gas Chromatograph's detection limit, but shows an increase of DMSPd with increasing depth and a maximum concentration at about 55 m below the surface. Although the obtained data showed mutlitple outliers, an exponential correlation between the methane and DMSPd - concentrations was distinguishable.

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