Interpretation of measured concentration profiles in sediment pore water

A robust numerical procedure for biogeochemical interpretation and analysis of measured concentration profiles of solutes in sediment pore water has b een developed. Assuming that the concentration-depth profile represents a s teady state, the rate of net production or consumption as a function of dep th can be calculated, together with the flux across the sediment-water inte rface. Three kinds of vertical transport can be included in the analysis: m olecular diffusion, bioturbation, and irrigation. The procedure involves fi nding a series of least square fits to the measured concentration profile, followed by comparisons of these fits through statistical F-testing. This a pproach leads to an objective selection of the simplest production-consumpt ion profile that reproduces the concentration profile. Because the numerica l procedure is optimized with respect to speed, one prediction can typicall y be done in a few minutes or less on a personal computer. The technique ha s been tested successfully against analytical solutions describing the tran sport and consumption of O-2 in sediment pore water. In other tests, measur ed concentration profiles of O-2, NO3-, NH4+, and Sigma CO2 have been inter preted using the new procedure.