Title

Composition and fluxes of submarine groundwater along the Caribbean coast of the Yucatan Peninsula

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Publication Date

April 2014

Abstract

Submarine groundwater discharge (SGD) to the coastal environment along the eastern Yucatan Peninsula, Quintana Roo, Mexico was investigated using a combination of tracer mass balances and analytical solutions. Two distinct submarine groundwater sources including water from the unconfined surficial aquifer discharging at the beach face and water from a deeper aquifer discharging nearshore through submarine springs (ojos) were identified. The groundwater of nearshore ojos was saline and significantly enriched in short-lived radium isotopes (223Ra, 224Ra) relative to the unconfined aquifer beach face groundwater. We estimated SGD from ojos using 223Ra and used a salinity mass balance to estimate the freshwater discharge at the beach face. Analytical calculations were also used to estimate wave set-up and tidally driven saline seepage into the surf zone and were compared to the salinity-based freshwater discharge estimates. Results suggest that average SGD from ojos along the Yucatan Peninsula Caribbean coast is on the order of 308 m3 d−1 m−1 and varies between sampling regions. Higher discharge was observed in the southern regions (568 m3 d−1 m−1) compared to the north (48 m3 d−1 m−1). Discharge at the beach face was in the range of 3.3–8.5 m3 d−1 m−1 for freshwater and 2.7 m3 d−1 m−1 for saline water based on the salinity mass balance and wave- and tidally-driven discharge, respectively. Although discharge from the ojos was larger in volume than discharge from the unconfined aquifer at the beach face, dissolved inorganic nitrogen (DIN) was significantly higher in beach groundwater; thus, discharge of this unconfined beach aquifer groundwater contributed significantly to total DIN loading to the coast. DIN fluxes were up to 9.9 mol d−1 m−1 from ojos and 2.1 mol d−1 m−1 from beach discharge and varied regionally along the 500 km coastline sampled. These results demonstrate the importance of considering the beach zone as a significant nutrient source to coastal waters for future management strategies regarding nutrien

Notes

Continental Shelf Research, Vol. 77 (2014-04-01).

Keywords

Radium Isotopes, Submarine Springs, Nutrient Loading, Submarine Groundwater Discharge, Mexico, Yucatan Peninsula

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1 online resource

Subject: topical

Radium Isotopes; Submarine Springs; Nutrient Loading; Submarine Groundwater Discharge; Mexico; Yucatan Peninsula

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Article

Genre

Serial publications

Identifier

SFS0055841_00001

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