This research is being developed in the Flona of Caxiuanã, in the municipality of Melgaço-PA, and aims to characterize hydrochemically and limnologically the water bodies: Curuá River (RCu), Caxiuanã River (RCx) and Caxiuanã Bay (SC) in two climatic periods (rain and drought), within the project "Integration of approaches to the environment, land use and social dynamics in the Amazon: human-environment relations and the challenge of sustainability MillenniumLSA2 - subproject Aquatic Siogeochemistry". Water sampling, with a Van Dom bottle, was carried out every three hours, for a period of 25 hours, at four depths. The parameters: water temperature (TA), pH, electrical conductivity (EC.), dissolved oxygen (0.0.) and average wind speed are being monitored at the sampling points. In the rainy period (January/08), the euphotic zone is represented by the total depth of SC (4 m) and RCx(8 m), where no stratification of any of the parameters was observed, and the differences between the top and bottom averages for RCx:EC. -0.91 j.LS.cm', 0.0.0.05 mg.l', pH -0.04, AI -0.01 "C; and for BC:EC. -0.0211S.cm'l', 0.0. -0.13 mg.l', pH 0.13, AI -O.03°C However, at RCu, the euphotic zone was at 8 m, the total depth being 9 m. Stratification occurred at this point for all parameters, forming three layers: 0.5-3.0 m (epilimnion): 5.5 m (metalimnion) and 8.0 m (hypolimnion), with the differences between the top and bottom averages for RCu being: EC. -l.92115.cm1, 0.0. 4.13 mg.l', pH 0.58, AI 0.63°C. The aquatic ecosystem of the Flona of Caxiuanã became a lake around 8,000 years ago, by the deposition of sediments in its bed. This could be identified in the behavior of the water characteristics at point RCu. It is expected that during the dry season a more pronounced stratification will occur, including at the other points surveyed.
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