Humic compounds in marine ecosystems - Ecological importance in transitional Mediterranean zones

Abstract

By using the general term ‘humic substances’ (HS), a vast category is implied of heterogeneous organic compounds that are naturally occurred, formed under certain circumstances, bearing yellow to black colour. There are distinguishable fractions of the (HS) categorized e.g. according to hydrophilicity. Humic acids (HA), comprise the soluble fraction of (HS) at high pH values whereas fulvic acids (FA) represent the soluble fraction of (HS) under all pH conditions. The humin represents the unclassified, non-soluble fraction of organic material. (HS) are separating into two well distinctive categories i.e. allochthonous & autochthonous indicating a different origin. (HS) affect bioavailability of transition metal ions including Fe, Mn, Cu, and Zn due to (HS) chelating properties and high affinity towards those metals. (ΗΑ) stimulate biodegradation and favors removal of various pollutants serving as bioremediation agents. Organic compounds leached from plastic debris into the aquatic phase, become part of the marine dissolved organic carbon (DOC) pool. Humic part characteristics are tightly bound to the anthropogenic impacts stressed over the shoreline and contribute to diagenetic processing of the marine seabed. The scope of the present essay was to outline the multi-functionality of humic substances in aquatic ecosystems with the given emphasis on the Eastern Mediterranean region.