Nitrogen and phosphorus in water and sediments at Ria Lagartos coastal lagoon, Yucatan, Gulf of Mexico

338-345Ria Lagartos, a hypersaline coastal lagoon in the Gulf of Mexico on the Yucatan peninsula was sampled three times in a year at 30 locations, in order to quantify the nitrogen and phosphorus available in the water column and sediments. Undisturbed samples of sediment were analyzed and incubated in the laboratory to estimate ammonium and phosphate fluxes between water and sediment together with nitrification and denitrification rates. The results indicated higher ammonium liberation (250±149 μmol m⁻² h⁻¹) and nitrification (151±132 μmol m⁻² h⁻¹), than denitrification (47±33 μmol m⁻² h⁻¹). In contrast phosphate liberation from sediments was found to be low (0.67±1.31 μmol m⁻² h⁻¹). The high concentrations of organic matter (3.73±1.65 %), total nitrogen (99.14±62.73 μmol g⁻¹), and phosphorus (4.42±1.82 μmol g⁻¹) in the sediments of the lagoon, indicate that can be a sink for these elements