A Biogeochemical Alkalinity Sink in a Shallow, Semiarid Estuary of the Northwestern Gulf of Mexico Academic Article uri icon


  • AbstractEstuarine totalalkalinity (TA), which buffers against acidification, is temporallyand spatially variable and regulated by complex, interacting hydrologic and biogeochemical processes. During periods of net evaporation (drought), the Mission-Aransas Estuary (MAE) of the northwestern Gulf of Mexico experienced TA losses beyond what can be attributed to calcification. The contribution of sedimentary oxidation of reduced sulfur to the TA loss was examined in this study. Water column samples were collected from five stations within MAE and analyzed for salinity, TA, and calcium ion concentrations. Sediment samples from four of these monitoring stations and one additional station within MAE were collected and incubated between 2018 and 2021. TA, calcium, magnesium, and sulfate ion concentrations were analyzed for these incubations. Production of sulfate along with TA consumption (or production) beyond what can be attributed to calcification (or carbonate dissolution) was observed. These results suggest that oxidation of reduced sulfur consumed TA in MAE during droughts. We estimate that the upper limit of TA consumption due toreduced sulfur oxidation can be as much as 4.60108molday1 in MAE. This biogeochemical TA sink maybe present in other similar subtropical, freshwater-starved estuaries around the world.

published proceedings


author list (cited authors)

  • Dias, L., Hu, X., & Yin, H.

complete list of authors

  • Dias, Larissa MM||Hu, Xinping||Yin, Hang

publication date

  • December 2022