THE ROLE OF UREA IN THE COASTAL NITROGEN BIOGEOCHEMICAL CYCLE AS A SIGN OF ENVIRONMENTAL HEALTH

Abstract

The urea is an organic nitrogenous compoundpresent in coastal environment introduced by excretion ofsome terrestrial and aquatic animals, including humanbeing. The estuarine-lagoon complex of Cananeia-Iguapeshows anthropic differences between northern and southernregions. Iguape is characterized beyond human occupation,by the presence of an artificial channel that introduce freshwater into estuary. Cananéia is naturally preserved. Thenorthern part showed salinity from 0.04 to 1.75 and ureafrom 0.66 to 1.49 μM. In the southern part, the salinityranged from 17.97 to 31.44 and the urea values ranged from0.01 to 2.46 μM. Analyses performed in samples takenduring 13h, in two fix points showed the depuration capacityof the southern part with association to the tide action. Themore constant urea values were observed in northern part,with similar values to the Ribeira river water. This studybelongs to VAGRA and INCT-TMCOcean projects.Index Terms ⎯ urea, estuarine system, nitrogenbiogeochemical cycle.