Geochemical study of the mobile metal/metalloid fraction and the fluorescent properties of the aqueous extracts of dissolved organic matter present in marine sediments from the Messiniakos gulf at the southern part of Greece

Abstract

Sediment samples from the Messiniakos gulf, at the southern part of Greece, were studied for the metals/metalloid content in the non-residual fraction and the fluorescent properties of the aqueous extracts of dissolved organic matter as both groups of metals/metalloid and dissolved organic matter are highly important from an environmental aspect. Applying the useful tool of Kriging method, prediction surfaces for each non-residual metal/metalloid were produced. Hierarchical cluster analysis and factor analysis with varimax rotation were performed on the data for the non-residual metal/metalloid content in sediments. The aqueous extracts of dissolved organic matter were characterized by fluorescence spectroscopy recording mono dimensional emission, excitation, synchronous-scan excitation and total luminescence spectra for the classification of chromophoric units present.In general, it was found that sediments from the central part of the gulf correspond to mobile metal fraction enrichment while those from the western gulf had lower values. Fluorescence studies in the DOM extracted from sediments revealed the presence of autochthonous organic matter with a low degree of aromatic polycondensation and a low level of conjugated chromophores. Fluorescence intensity and humification decrease in buried sediments. Samples with more humificated structures were also the ones having more intense peaks.Spatial and vertical distributions of temperature, salinity and chlorophyll content in the water column were also studied.