Study of dissolved nitrogen forms and environmental parameters in estuaries with different tidal variations José Elias Ferreira do Nascimento, Vitor Gonsalez Chiozzini, Samara Aranha Eschrique, Elisabete de Santis Braga

Abstract

The study of the biogeochemical cycle of nutrients, including nitrogen, in estuarine environments is of paramount importance for the knowledge of the potential for the maintenance of life. Nitrogen acts in the production of organic matter and can be found in different forms in water. This study aims to know the balance between inorganic nitrogen forms dissolved in surface waters in two estuaries, one subject to micro-tidal action - the Cananéia-Iguape Estuarine-Lagoon Complex (CIELC-SP) and the other under the action of macro-tidal, in the Raposa and Paciência Estuarine System (RPESMA), both in the rainy season. The maximum values of ammonium-N and nitrate were respectively 1.84 µmol L-1 and 13.92 µmol L-1 in CELCI and 36.53 µmol L-1 and 10.30 µmol L-1 in SERP. The values indicated the greatest variations in the system under the action of the macro tide, which revealed higher values of ammonium-N in relation to nitrate, the most stable form of nitrogen, which indicates the vulnerability of this system and the exposure to anthropic action more evident.