Geochemical rates estimated from two-dimensional distributions of dissolved iron and phosphate from an intertidal estuarine mudflat

Aubin Thibault de Chanvalon, Edouard Metzger, A Mouret, Florian Cesbron, J. Knoery, P Launeau, E Geslin, Sebastiaan Van De Velde, Filip Meysman

Research output: Chapter in Book/Report/Conference proceedingMeeting abstract (Book)


Sediment diagenesis generates chemical fluxes through the sediment-water interface which can strongly impact the water column. The reductive dissolution of iron (hydr)oxides in the Loire estuary sediment is an important diagenetic process in the first 20 cm depth, and forms a possible source of dissolved phosphate and trace metals to the river. Here we propose a new numerical model technique to estimate the production rates of ferrous iron and other solutes from two-dimensional (2D) concentration distributions. Based on the Savitzky Golay filter approach, this model approach suitably “denoises” the measured concentration data and allows to calculate the first order derivative (providing the flux) and the second order derivative (providing the production rate) in a numeral robust way. The new approach was applied to test one-dimensional depth profiles and compared to the widely used “PROFILE” software . Subsequently, we applied the new technique to estimate the production rates from a 2D pore water data set obtained by a combined DET-gel/colorimetry technique . Two mains sources of heterogeneity are described: the bioirrigation of sediment by macrofauna and the patchiness of labile organic carbon. By coupling dissolved iron with dissolved phosphate data set, followed by inverse production rate modeling, we are able, for the first time, to study the impact of this heterogeneity on iron cycle and its consequences on phosphorus mobilization.
Original languageEnglish
Title of host publicationMarine Chemistry
Publication statusPublished - 2015
Event13th International Estuarine Biogeochemistry Symposium - Université de Bordeaux, Bordeaux, France
Duration: 7 Jun 201510 Jun 2015


Conference13th International Estuarine Biogeochemistry Symposium


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