Innovative microcosm experiments for the evaluation of the regeneration rates of nutrients in sediments of a hypersaline lagoon.

The aim of this study was to evaluate the regeneration of nutrients from the sediments to the water column in varying salinities, with an innovative experiment that closely simulates real environment. In vitro experiments were carried out simulating six scenarios with two sediment types (low carbonate and high carbonate). Local water and sediments were added to microcosms where circulation was forced. Results showed nitrogen release from low carbonate sediment in the lagoon, mixed and seawater (1.69, 4.68 and 7.36 μmol m-2 day-1, respectively). Phosphate diffusive fluxes were positive in lagoon water and low carbonate sediment (2.24 μmol m-2 day-1), negative with mixed water (-0.30 μmol m-2 day-1) and seawater (-0.51 μmol m-2 day-1). A phosphate release surge was observed in the low-carbonate sediment with overlying mixed water and seawater that, in the natural environment, may boost primary production.