Journal of Soils and Sediments, June, 2013, Vol.13(6), p.1113(10)
Byline: Katja Heister (1), Sabine Pols (1,2,3), J. P. Gustav Loch (2), Tom N. P. Bosma (2) Keywords: Organic carbon--water partitioning coefficient; Organic matter characterisation; PAH; Sediment Abstract: Purpose The desorption behaviour of 16 polycyclic aromatic hydrocarbons (PAHs) in sludges from two sites of the port of Rotterdam, The Netherlands, which are designated to be stored in a subaqueous sludge depository, was investigated after a storage time of 14 years at 4 degC under anaerobic conditions in the dark, mimicking depository conditions. Such long-term storage is believed to effect the desorption of the PAHs. Materials and methods Batch desorption experiments over a time period of 130 days were performed with the brackish Beerkanaal (BK) sludge and the freshwater Beneden Merwede River (BMR) sludge. The organic carbon--water partitioning coefficient (K .sub.OC) values were calculated and compared to values of a previous study on the same sludges after a storage time of 3 years and to values obtained from calculations based on octanol--water partitioning coefficient (K .sub.OW) values. Additionally, the organic matter of the sludges was characterised by C and N elemental analysis and solid-state 13.sup.C nuclear magnetic resonance spectroscopy. Results and discussion Only desorption of low molecular weight PAHs up to pyrene was detected. Several K .sub.OC values were higher compared to the values from the previous study, and all were increased compared to values based on K .sub.OW values. It is assumed that the increase in K .sub.OC was an effect of the prolonged contact time, causing slow intradomain diffusion of PAHs into the condensed carbon domains. Desorption was higher in BK than in BMR, which is explained by differences in organic matter composition because BMR (containing predominantly aromatic carbon) and BK (which was dominated by lipids) contained the same amount of organic carbon. It is inferred that lipids compete with PAHs for sorption sites on the aromatic carbon, so that lipids block these sorption sites, and the PAHs are adsorbed to the lipids. Conclusions Since the amounts of PAHs desorbed from both sludges in this study were so low, it is supposed that long-term storage of these sludges in subaqueous depositories will likely result in increased sorption and thus a reduced release of these contaminants into the environment over time. Author Affiliation: (1) Lehrstuhl fur Bodenkunde, Technische Universitat Munchen, 85350, Freising-Weihenstephan, Germany (2) Department of Earth Sciences, Faculty of Geosciences, Utrecht University, P.O. Box 80021, 3508 TA, Utrecht, The Netherlands (3) Provincie Noord-Holland, P.O. Box 3007, 2001 DA, Haarlem, The Netherlands Article History: Registration Date: 22/03/2013 Received Date: 11/06/2012 Accepted Date: 22/03/2013 Online Date: 12/04/2013 Article note: Responsible editor: Trudy J. Estes Electronic supplementary material The online version of this article (doi: 10.1007/s11368-013-0689-z) contains supplementary material, which is available to authorized users.
Lipids -- Analysis ; Polycyclic Aromatic Hydrocarbons -- Analysis ; Nuclear Magnetic Resonance Spectroscopy -- Analysis