Characterization of humic substances in highly polluted river sediments by pyrolysis methylation–gas chromatography–mass spectrometry

• Published in: Organic geochemistry 2001-01, Vol.32 (2), p.223-231
• Main Authors: Mansuy, Laurence, Bourezgui, Yassine, Garnier-Zarli, Evelyne, Jardé, Emilie, Réveillé, Véronique
• Format: Article
• Language: English
• Subjects: Earth Sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environmental Sciences; Exact sciences and technology; France, Lille, Deule R; Freshwater; Geochemistry; Marine and continental quaternary; Pollution, environment geology; Sciences of the Universe; Soil and rock geochemistry; Surficial geology
• ISSN: 0146-6380; 1873-5290
• DOI: 10.1016/S0146-6380(00)00169-8

Humic substances were extracted from two sediment cores sampled in a river on the outskirts of a large city (Deûle near Lille, France) and in its highly polluted oxbow-lake. Humic acids (HA) were characterized by infrared spectroscopy and in situ pyrolysis/methylation–gas chromatography–mass spectrometry. The main results are the substantial aliphaticity of HA in the oxbow-lake at all depths, mainly due to the presence of a lipid fraction associated with the HA structure. The abundance of sterols in this fraction implies that lipids could originate from the accumulation of sewage in the oxbow-lake. Humic acids of the Deûle sediments show a different trend ; their evolution is characterized by a decrease of the pollutant inputs with increasing depth. The results demonstrate the efficiency of Py–GC–MS in identifying the different organic contributions to HA and in distinguishing natural from anthropogenic sources.