Dinâmica das formas dissolvidas de nitrogênio e carbono em microbacias da Mata Atlântica no município de Ubatuba (SP) / Dynamics of dissolved forms of nitrogen and carbon in small watersheds of the Atlantic Forest, at Ubatuba - Brazil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Based on the fact that streams water quality reflects the conditions of the landscape, the objectives of this study were: to investigate nitrogen (N), carbon (C) and major ions dynamics in six streams covered by Atlantic Forest; and assess the impacts of the human activities over the biogeochemistry of two urban streams at same region. Since this study is part of BIOTA Thematic Project Functional Gradient, N and C fluxes were determined at one of the streams, in order to contribute with the estimation of nutrient balances for the Atlantic Forest. Eight streams were selected at Ubatuba, State of São Paulo. Water was monthly sampled from Sept-06 to Dec-07 at all streams. At one of the streams (Indaiá) water samples were taken every two days from Dec-06 to Mar-08; and also water samples were collected every hour during a 48h period at Mar-08. The pristine watersheds showed the same pattern in terms of distribution of biogenic gases, C, N and major ions concentrations in the streamwater. The urban streams were significantly different from the pristine streams regarding to: (i) aquatic metabolism - low dissolved oxygen concentrations, high carbon dioxide concentrations and high respiration rates; and (ii) nutrient and major ions concentrations - high dissolved inorganic nitrogen and carbon concentrations as well as high ionic concentrations. These differences were attributed to anthropogenic impacts at water quality, especially domestic sewage discharge. Besides, it was found relatively high fluxes of dissolved organic carbon (6.9 kg C ha-1 yr-1), dissolved inorganic carbon (22.4 kg C ha-1 yr-1), and dissolved inorganic nitrogen (3.2 kg N ha-1yr-1). Through the 48h sampling at Indaiá stream it was possible to observe the importance of intense rainfalls events over temporal dynamics of dissolved carbon forms and major ions concentrations. These results reveal the influence of human activities over the biogeochemistry of costal streams and also show the importance of Atlantic Forest hydrological fluxes of dissolved C and N to the ocean.

ASSUNTO(S)

bacia hidrográfica ecossistemas aquáticos streams mata atlântica atlantic forest. nitrogênio carbono carbon rios. nitrogen Íons major ions

ACESSO AO ARTIGO

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