Influence of water management and natural variability on dissolved inorganic carbon dynamics in a mangrove-dominated estuary

Chiara Volta; David T Ho; Gernot Friederich; Victor C Engel; Mahadev Bhat

doi:10.1016/j.scitotenv.2018.04.088

Influence of water management and natural variability on dissolved inorganic carbon dynamics in a mangrove-dominated estuary

Sci Total Environ. 2018 Sep 1:635:479-486. doi: 10.1016/j.scitotenv.2018.04.088. Epub 2018 Apr 24.

Authors

Chiara Volta¹, David T Ho², Gernot Friederich, Victor C Engel³, Mahadev Bhat⁴

Affiliations

¹ Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA. Electronic address: cvolta@hawaii.edu.
² Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA.
³ U.S. Forest Service, Fort Collins, CO 80526, USA.
⁴ Department of Earth and Environmental, Florida International University, Miami, FL 33199, USA.

PMID: 29677673
DOI: 10.1016/j.scitotenv.2018.04.088

Abstract

High-resolution time series measurements of temperature, salinity, pH and pCO₂ were made during the period October 2014-September 2015 at the midpoint of Shark River, a 15km tidal river that originates in the freshwater Everglades of south Florida (USA) and discharges into the Gulf of Mexico. Dissolved inorganic carbon dynamics in this system vary over time, and during this study could be classified into three distinct regimes corresponding to October 2014-February 2015 (a wet to dry season transition period), March-May 2015 (dry period) and July-September 2015 (wet period). Average net longitudinal dissolved inorganic carbon (DIC) fluxes and air-water CO₂ fluxes from the Shark River estuary were determined for the three periods. Net DIC fluxes to the coast were estimated to vary between 23.2 and 25.4×10⁵mold^-1 with an average daily DIC flux of 24.3×10⁵mold^-1 during the year of study. CO₂ emissions ranged between 5.5 and 7.8×10⁵mold^-1 with an average daily value of 6.4×10⁵mold^-1 during the year. The differences in estuarine carbon fluxes during the study period are attributed to differences in the relative importance of hydro-climatological drivers. Results suggest that, during months characterized by reduced rainfall, carbon fluxes are affected by water management via control structures in the upstream Everglades marshes. During months with high rainfall, when culverts are closed and rainfall events are more frequent, carbon fluxes depend more on other forcings, such as rainfall and groundwater discharge.

Keywords: Carbon dioxide; Dissolved inorganic carbon; Estuaries; Everglades; Mangrove ecosystems; Shark River.