Reactive oxygen species control mineralization in permeable intertidal sediments

We investigated the influence of reactive oxygen species (ROS) on microbial mineralization in intertidal permeable sediments. These sediments are crucial for coastal carbon cycling. Permeable intertidal sediments are further prone to variable surface oxygenation and active iron-sulfur cycling, and are therefore likely sites of intense ROS formation. We incubated sediment slurries from an intertidal sandflat in the German Wadden Sea over a transition to anoxic conditions, and found that removal of ROS by enzymes increased rates of aerobic and anaerobic respiration, including sulfate reduction. We additionally found high concentrations of the ROS hydrogen peroxide in sediment porewaters. Sulfate reduction was absent during the oxic period, but directly resumed upon anoxia.

This study shows the regulating effect of ROS on microbial mineralization and the impact of ROS and transient oxygenation on marine sediment biogeochemistry.