STUDIES OF THE DOM AQUEOUS EXTRACTS FROM COASTAL MARINE SEDIMENTS

1. STUDIES OF THE DOM AQUEOUS EXTRACTS FROM COASTAL MARINE SEDIMENTS F. Sakellariadou Lab. of Oceanography and Marine Geochemistry, Dept of Maritime Studies, University of Piraeus, 21 Gr. Lambraki & Distomou st, Piraeus 18532, Greece, email: fsakelar@unipi.gr • Present study: • • Coastal sediment samples were collected from Messiniakos gulf in the south western Peloponnese in South Greece. • • Dissolved organic matter was extracted under gentle extraction conditions (4 mM CaCl2 solution). • The various classes of organic components present at the DOM aqueous extracts were characterised by fluorescence spectroscopy. represents a major exchangeable organic pool playing an outstanding role in the ocean carbon cycle. has a complex chemical structure made up of a wide range of organic molecules. has a composition that depends on the sources proximity and the exposure to any sort of degradation mechanism. interacts with pollutants either by enhancing their bioavailability or by influencing their transportation to the soluble phase. affects the remineralisation of carbon and its preservation in marine sediments. has a terrestrial, freshwater or marine origin. • Fluorescence spectra: • Conventional (mono dimensional emission, excitation and synchronous –scan excitation) spectra were recorded. • Total luminescence (TL) in the form of excitation/emission matrix (EEM) spectra (or contour maps) were recorded • Humification indices according to Ohno (2002) and Zsolnay (1999) were calculated Map of Greece, with ▲ is shown the study area. Map of the study area with the sampling sites. Results All fluorescence spectra were thoroughly evaluated for the classification of chromophoric units present. Variations were observed according to: ► the sampling site and more precisely its proximity to the coastline and the corresponding water column’s depth; ► the oceanographic characteristics allowing or obstructing sea water circulation; ► the proximity of each sample to the seabed, in other words the characterization of each sediment sample as surface of subsurface one. Mono dimensional emission spectra. Excitation spectra Synchronous scan excitation spectra. Selected EEM (3D) spectra. References [1] Burdige, D.J., Kline, S.W., Chen, W., 2004. Fluorescent dissolved organic matter in marine sediment pore waters. Marine Chemistry, 89, 289-311. [2] Ohno, T. 2002. Fluorescence inner-filtering correction for determining the humification index of dissolved organic matter. Environ. Sci.and Technol., 36, 742-746. [3] Zsolnay,A., Baigar, E., Zimenez, M., Steinweg, B., Saccomandi, F., 1999. Differetiating with fluorescence spectroscopy the sources of dissolved organic matter in soils subjected to drying. Chemosphere 38:45-50. [4] Cobble, P.G., 1996. Characterisation of marine and terrestrial DOM in seawater using excitation-emission matrix spectroscopy. Marine Chemistry51:325-346. [5] Senesi, N., Miano, T.M., Provenzano, M.R., and Brunetti, G., 1991. Characterization, differentiation, and classification of humic substances by fluorescence spectroscopy. Soil Science 152(4): 259-271. European Geosciences Union, General Assembly 2012, 22-27 April 2012. Vienna, Austria