PEIXOTO, R. H. P. B.; http://lattes.cnpq.br/0259935674162461; PEIXOTO, Ricardo Henrique Paes Barreto.
Resumo:
The present work aimed to study the variation of the physical and chemical characteristics of
Tocantins river (TO), downstream the UHE Serra da Mesa in the area defined from the
confluence of Cana-Brava River to the confluence of the Parana River (83 km), along a period
of 2 years. Data were obtained from a research project named: "Limnological monitoring of
Tocantins river downstream of UHE Serra da Mesa", as part of an agreement between the
University of Tocantins and Serra da Mesa - Energy S/A and FURNAS - Centrais Eléctricas
We tried to obtain the largest volume of available information referring to parameters related
with water quality. Tocantins River is of multiple use (domestic supply, animal fed, clothes
washing, tourism, leisure, fishing energy generation and unrestricted irrigation). The
Tocantins river basin presents drainage 757.000 mVs and medium discharge of long period of
11.800 mVs. Bimonthly samplings were accomplished in seven collection points, in the period
from may/98 to mar/00 two rainy and two dry seasons for the following parameters: pH,
temperature, conductivity, transparency, color, turbidity, OD, chlorophyll a, reactive
phosphate, ammonium and nitrate, chloride, sodium, potassium, silica, calcium, total
alkalinity and total hardness. The physical and chemical characteristics observed showed that
water quality of Tocantins River is adequate for its several purposes destination considering
the parameters for water quality stated by CON AM A Resolution 020/86. The concentrations
of nutrients evidenced that the area doesn't receive contributions that can become immediate
agents of degradation of water quality. In fact, the rater of N and P corresponded to the level
of oligotrophic waters. We intend to continue the monthly monitoring, in order to obtain
longer temporal series that would allow a deeper study of the tendencies for eutrophication
and of the possible impacts of UHE Serra da Mesa in the water quality of Tocantins River.
