A Biogeochemical Model Tuned to Quantify Benthic Iron and Sulfur Cycling on the Oregon Shelf and Slope

Iron is an essential micronutrient for primary productivity and can often be limiting, even in productive coastal ecosystems. Studies suggest that the sediments of continental margins may be a major source of dissolved iron to the photic zone. In this study, we model pore water and solid-phase sedimentary iron and sulfur using a reaction-transport model framework introduced by van de Velde and Meysman (2016), and we adjust it to represent benthic flux chamber and down-core chemical data from the Oregon shelf and upper slope with the ultimate goal of modelling deeper sites for which data is sparse. We focus on the efficacy of this tuned model to reproduce fluxes and concentrations of iron and sulfur species in bioturbated muddy sediments with sedimentation rates of 0.5 - 3 mm y^-1 (based on ²¹⁰Pb geochronologies). Ultimately, wider application of a benthic biogeochemical model for the many diverse environments on the Oregon margin may provide improved regional assessments of biogeochemical cycling of iron in locations where benthic sampling can be challenging and in environments impacted by forms of anthropogenic disturbance such as bottom trawling.

van de Velde, S. & Meysman, F.J.R. Aquat Geochem (2016) 22: 469. https://doi.org/10.1007/s10498-016-9301-7