Characterization of natural organic matter from Mediterranean coastal seawater
نویسندگان
چکیده
Natural organic matter (NOM) is a complex mixture of organic compounds present in all fresh water. NOM is usually only roughly characterised through conventional analytical techniques. In this study, advanced analytical techniques such as XAD fractionation, LCOCD, EEM fluorescence and membrane separation have been applied for NOM seawater characterization. Conventional analyses have shown that Mediterranean coastal seawater has a low content of natural organic matter, poorly aromatic and low biodegradability. Advanced analyses permit to better characterize NOM separating the whole into different group. NOM has been defined as mainly hydrophilic (70%) and slightly transphilic (24%) by XAD fractionation. From LC-OCD results, seawater appears mainly composed of humics and LMW neutrals (37 and 40% of DOC, respectively). The LMW neutrals are hydrophilic whereas humics contains hydrophobic, transphilic and hydrophilic that shows the advanced hydrolysis of humics in seawater. Fluorescence shows a higher contribution of fulvic acid-like compounds than humic acid-like. Separation by membrane has shown as well that NOM has a molecular size lower than 1kDa. This confirms the hypothesis of an advanced degradation of humic substances. It has been shown also that fraction > 1kDa contains mainly aromatic protein more biodegradable than the pool of seawater NOM.
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