Sediment resuspension is rarely considered when assessing benthic carbon mineralization in coastal environments. Using a hydrodynamically calibrated sediment erosion device (EROMES), we quantified the impact of erosion events on benthic biogeochemistry across 4 seasons. Enhanced sediment erosion increased the benthic O₂ uptake rate and the release of dissolved inorganic carbon (DIC). This was mainly associated with the reoxidation of FeS_x and enhanced mineralization of organic carbon, and for the latter due to a porewater washout of DIC. Sediment resuspension changes the redox conditions and increases the oxygen penetrations depth, with implications for the benthic N and P dynamics. Sediment resuspension is thus an important player in stimulating local primary production and maintaining the sulfide buffer capacity in coastal environments. The impact of sediment resuspension on the benthic environment varied across the season and was mainly driven by the size of the FeS_x pools within the sediment. The effect of sediment resuspension on the near bed O₂ consumption rate as compared to pre suspension rates was highest in August and lowest in January with 4- and 2-fold increases, respectively. Repeated subsequent resuspension events gradually reduced the impact of a given resuspension event. This study shows that sediment resuspension is an important but overlooked factor for the biogeochemical function of coastal environments that needs more attention in future studies to access responses towards anthropogenic and climatic impacts.

Primary Presenter: Lisbeth Sørensen, University of Southern Denmark (lisbethf@biology.sdu.dk)

Authors:

Lisbeth Sørensen, University of Southern Denmark  (lisbethf@biology.sdu.dk)

Karl Attard, University of Southern Denmark  (karl.attard@biology.sdu.dk)

Thorbjørn Andersen, University of Copenhagen  (tja@ign.ku.dk)

Ronnie Glud, University of Southern Denmark  (rnglud@biology.sdu.dk)