Dissolved organic matter extracted from groundwater and heavy metals behavior in Ain Senan-Kef, Tunisia

Abstract In this study, dissolved organic matter (DOM) extracted from Tunisian water was examined using elemental analysis, size exclusion chromatography, nuclear magnetic resonance spectroscopy, pyrolysis gas chromatography-mass spectrometry and fluorescence spectroscopy. DOM has been quantified with parameters including ultraviolet–visible, total organic carbon, chemical oxygen demand and specific UV-absorbance. Elemental analysis indicated that groundwater contained a high amount of oxygen but a low amount of carbon. Based on fluorescence indices, organic matter is dominated by biological/autochthonous species, which are typically observed in the waters. The use of GC/MS revealed the presence of proteins. The interactions of heavy metals (Hg, Zn and Cu) with DOM have been studied using X-ray diffraction, ICP-AES, Fluorescence and FTIR spectroscopies. Zn appears to be bound to humic acid primarily through carboxyl-functional groups, while Hg ions apparently are bound through carboxylic, phenolic and alcoholic moieties. Cu (II) is bound preferentially to oxygen and nitrogen containing functional groups. Organic matter was supposed to be organomineral complexes.