Modelling macro-nutrient release and fate resulting from sediment resuspension in shelf seas

Wood, C.C., Kelly-Gerreyn, B.A., Statham, P.J., Aldridge, J.N., Fones, G.R., Couceiro, F and Thompson, C.E.L. (2011) Modelling macro-nutrient release and fate resulting from sediment resuspension in shelf seas. 12th International Symposium on the Interactions between Sediments and Water, Totnes, United Kingdom. 19 - 23 Jun 2011.

Abstract

Early diagenesis (ED), the physical and biogeochemical changes undergone in surficial sediments, plays an important role in the biogeochemical cycles of key elements (carbon, nitrogen and oxygen) in highly productive shelf-seas. Modelling the process uses a relatively simple set of mathematical equations to represent the transport and reaction terms. We have calibrated an existing steady-state ED model, which we have expanded to include more processes and variables (e.g. mineralisation of organic matter using iron oxide and sulphate) to examine the fate of the nutrients through sediment water exchanges.

Biogeochemical cycles can be affected by resuspension as a result of release or uptake of nutrients, which can also have a considerable effect on primary productivity. Resuspension is a wide-spread transport process in shallow seas due to winds, tides and biological activity. In contrast to previous diagenetic modelling, we aim to model resuspension and its effect on nutrient cycling. We will also study the resuspension effects on reactions such as the reoxidation or burial of reduced compounds and associated nutrients.

We will present results from the modelling experiments, showing the relative role of various oxidising agents (oxygen, nitrate, iron oxide and sulphate) during the degradation of organic matter in the sediments. Observations made in the North Sea provide suitable data to calibrate the model. Current results show that the model is able to give realistic representations of sedimentary nutrient profiles from the North Sea. We aim to present preliminary results showing the effect of resuspension on the transport processes of nutrients across the sediment-water interface, and will discuss the implications that this may have on the calculation of nutrient budgets in continental shelf seas.
preliminary results showing the effect of resuspension on the transport processes of nutrients across the sediment-water interface, and will discuss the implications that this may have on the calculation of nutrient budgets in continental shelf seas

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Contributors

Author: C.E.L. Thompson

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