Organic matter in thermal, cold ground and surface waters of the Far East south continental part (oxygen-containing compounds)

This article presents the composition and molecular weight distribution of medium volatility oxygen-containing organic compounds in the thermal, cold ground and surface waters of the continental part of the Far East south. Using the method of capillary gas chromatography-mass spectrometry, it is found 71 oxygen-containing compounds in thermal waters, belonging to 10 homologous series, and in cold ground and surface waters - 36 compounds, belonging to 7 homologous series. Their relative content in the medium volatility organic matter composition is about 55% in thermal waters and about 45% in cold ground and surface waters. Esters, carboxylic acids and aldehydes are widespread in hot waters. These compounds are widely produced in the biosphere and are probably of biogenic origin. The features of the carboxylic acids and aldehydes molecular weight distribution (the predominance of homologues with an even number of carbon atoms in the molecule) also show their biogenic genesis. The formation of ethers can as well be associated with the oxidation of organic matter in water-bearing rocks, and aromatic and nitrogen-containing components - with thermogenic processes occurring in hydrothermal systems. Esters, steroids and ketones also reach their maximum relative concentrations in cold waters. Steroids predominate in the oxygen-containing organic compounds composition in cold ground and surface waters where the carboxylic acids distribution is insignificant. Among the revealed compounds, in thermal waters there are some components - indicators of technogenic pollution. These are the compounds containing a tert-butyl group and DETA. However, their share in the composition of medium volatility organic matter is insignificant.