Organic-geochemical characteristics of the mud from the Techirghiol Lake, Romania

Abstract

The Techirghiol Lake, located on the Romanian coast of the Black Sea, is a hypersaline lake. In this environment, a unique ecosystem in Europe has developed with the specific capacity of producing mud by the decomposition of flora and fauna under the microbial activity (saprogenic sludge), which is used for therapeutic purposes. In this study, hydrocarbon compositions of the Techirghiol Lake mud are investigated in order to determine the origin and type of organic matter (OM). All samples are characterized by a high abundance of n-alkanes, short and high chain alkenes, pimarane, phyllocladane, indicating that OM was mainly derived from phytoplankton, filamentous green alga Cladophora vagabunda, Cyanobacteria, submerged/floating macrophytes, terrestrial and emergent plants. The terrestrial origin of organic matter is probably related to a significant input by wind or rivers. Typical oil distributions of terpanes and steranes biomarkers clearly indicate that the muds of Techirghiol Lake, in addition to native organic matter, contain a relatively low contribution of petroleum type pollutants, as well as PAH compounds of pyrogenic origin. The relatively high abundance of 1-chloroalkenes, which in some samples represent the most abundant compounds in the total distribution of hydrocarbons, together with isoprenoid thiophenes indicate the local presence of significant amounts of chloride and sulphur species in the water column or surface sediment.