NUTRIENTS AS INDICATORS OF ENVIRONMENTAL CHANGES IN TWO BRAZILIAN ESTUARINE SYSTEMS

Abstract

This study quantified nutrients in twocontrasting estuarine systems: Iguape (SP) on thesoutheastern coast of Brazil, influenced by erosion,agriculture and urbanization, and under the influence of animportant river flow (Ribeira de Iguape), which reaches theestuary via artificial channel (Valo Grande); and, Jaguaribe(CE), on the northeastern coast under semi-arid climate,submitted to domestic and shrimp farm effluents. Thehydrochemistry during the rainy period in June 2007(Jaguaribe) and February 2009 (Iguape) showed stronginfluence of terrestrial drainage reflected by low salinitybetween 2.30 and 4.50 (Jaguaribe) and from 0.04 to 0.84(Iguape). Dissolved nutrient concentrations varyconsiderably. In the Jaguaribe: N-ammonium (8.04-13.51μM), nitrite (0.03-0.09μM), nitrate (0.30-0.43μM),phosphate (1.60-1.94μM) and silicate (202.20-232.62μM);which were different from Iguape: N-ammonium (0.76-2.04μM), nitrite (0.20-0.30μM), nitrate (15.27-16.08μM),phosphate (1.47-1.68μM) and silicate (98.89-187.56μM).Data showed nutrients can be an important tool to monitorthe environmental impact of human activities. INCTTMCOcean,CNPq 573601/2008-9.Index Terms ⎯ Anthropogenic influences, dissolvednutrients, estuarine systems.