Fig. 5: Conceptual diagram.
Seagrasses can decrease the concentration of accumulated sulfide (H2S) through oxygen (O2) pumping in the rhizosphere, which fuels sulfide oxidation and produces protons (H+). Incomplete sulfide oxidation produces sulfur intermediates which are also reactive towards organic matter (i.e. Sx2-, SO32-, S2O32-), which along with accumulated sulfide, leads to sulfurization of CAOM. Carbonate dissolution using H+ derived from sulfide oxidation releases CAOM to the porewaters, in an iterative process as reprecipitation is promoted in part through sulfate reduction. Paired sulfur and inorganic carbon cycling leads to increased DOS composition of surface water DOM.
