Carbon and nitrogen dynamics in rivers of the alto Paraíba do Sul watershed, São Paulo State

Abstract

Several authors highlight the urgent need for additional research related to the structure and functioning of the Atlantic Forest, especially those related to nutrient cycling. River water chemistry is being employed to investigate the processes which encompass the natural cycling of these nutrients that are influenced among other factors, by land use change, which promotes alterations of the characteristics of rivers, being the most notable ones those related to Carbon (C) and Nitrogen (N) cycles. The present research aims the investigation of the dynamics of N and C, of Paraíba do Sul river, and of its tributaries, the Paraitinga and Paraibuna, which cross areas of different land use, as well as the understanding of how these changes in land use (forest to pastureland) affect the dynamics of these nutrients in small 1st and 2nd order rivers, indirect tributaries of the Paraíba do Sul. The first results show small variation among the 1st order rivers located in forest and pasturelands, even with land use change. Concerning the Paraibuna, Paraitinga and Paraíba do Sul Rivers, the concentrations continue low, despite the present antropic pressure. Some variables still need to be analyzed. After the ending of the analyzes a practice of 6 months is going to be performed at the Department of Ecology and Evolutionary Biology, of Cornell University, located in Ithaca, New York, USA, aiming the analyzes and interpretation of the obtained data. We believe that the accomplishment of the present project, with a partnership with Professor Robert Warren Howarth, is going to contribute with the understanding of the biogeochemistry processes in these tropical rivers, contributing with future actions of conservation and management. (AU)