Desorption kinetics of ammonium and methylamines from estuarine sediments: consequences for the cycling of nitrogen

Fitzsimons, Mark F. and Millward, Geoffrey E. and Revitt, D. Mike and Dawit, Mekibib D. (2006) Desorption kinetics of ammonium and methylamines from estuarine sediments: consequences for the cycling of nitrogen. Marine Chemistry, 101 (1-2). pp. 12-26. ISSN 0304-4203

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Concentrations of dissolved and particulate NH4+ and mono-, di- and trimethylamines (MAs) were determined in surface sediments and pore-waters collected from the Thames Estuary, United Kingdom, during July and November 2001. Dissolved NH4+ was an order of magnitude more abundant than the MAs in the pore-waters, whereas in the solid phase each MA was more abundant than NH4+. Sediments were also used in controlled, time-dependent, desorption experiments, using indigenous, filtered seawater. Desorption of NH4+ was more rapid than the MAs and the kinetics were interpreted using a reversible first-order mechanism. The mean response times (i.e. time taken to achieve 63% of the new equilibrium) of NH4+ and MAs were about 15 and 25 min, respectively. Increases in the concentrations of dissolved NH4+ and dissolved MAs, in the Thames Estuary over a tidal cycle, were coincident with the remobilisation of seabed sediments. Model calculations showed that desorption of NH4+ from the remobilised sediments accounted for approximately 50% of increase, whereas for MAs it was > 90%. The results are proposed as a predictor for the sorption behaviour of other organic nitrogen compounds, such as basic amino acids, and emphasise the importance of sediment resuspension as a mechanism for the release of ON to the water column.

Item Type:Article
Research Areas:A. Middlesex University Schools and Centres > School of Science and Technology > Natural Sciences
Citations on ISI Web of Science:14
ID Code:3860
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Deposited On:28 Jan 2010 07:29
Last Modified:20 Feb 2015 11:33

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