Spatial Variability of Organic Matter and Phosphorus Cycling in Rhône River Prodelta Sediments (NW Mediterranean Sea, France): a Model-Data Approach

The Mediterranean Sea (MS) is a large oligotrophic sea whose productivity sensitive to riverine nutrient inputs. More specifically, phosphorus (P) river supply crucial for the MS, with an important role of estuarine/deltaic filter especially storage and recycling in sediments. A benthic dataset from Rhône River prodelta was used derive P budgets, by means early diagenetic model including cycle. fitted pore water profiles oxygen, nitrate, sulfate, dissolved inorganic carbon, ammonium, oxygen demand units, (DIP) solid data (organic carbon (OC), Fe-bound P, Ca-bound organic P). Results indicated that intensity biogeochemical processes occurring below sediment–water interface decreased mouth adjacent continental shelf decreasing integrated rates OC mineralization (160–10 mmol m−2 day−1). intense near offshore (1196–80 μmol Its contribution DIP release (> 90%). had key transferring deeper layers. These deltaic sediments played as source regenerated DIP. significant part recycled overlying waters (72–94%), representing 25% discharge. Simultaneously, 6–28% produced buried P. Overall, this study highlighted importance additional coastal sea, minor but permanent sink burial.