Caracterização dos parâmetros químicos e físico-químicos do rio Curuá, região de Caxiuanã, Pará.

Abstract

The research was conducted in the region of Caxiuanã, in the Caxiuanã National Forest, protected area where the Ferreira Penna Scientific Station is located, with the objective of characterizing the surface water of the Curuá River, through physical-chemical and chemical parameters. The field activity was carried out in November 2004 (dry season). Eight sampling points were established, distributed among the rivers Curuá, Caxiuanã and Saia de Caxiuanã; point 8 represents well water. At the collection site temperature (0C), pH, electrical conductivity (EC), Total Dissolved Solids (TDS) and salinity were measured. In the laboratory, chemical analyses were performed according to Standard Methods. The samples presented acidity around 3.9 to 5.3. The temperature reflected the climatic conditions of the region, with an average of 30.33°C. The color ranged from 26 to 46UC (points 1 to 7), and point 8 had a color of 10UC, in accordance with the ordinance #518 of the Ministry of Health. The minimum and maximum values found for turbidity were 7.0 and 25.05NTU, respectively. In the period of lower rainfall intensity, the EC reached a mean value of 27.94 IJS/cm, in Curuá River, 27.4 IJS/cm, in Caxiuanã River, 26.7 IJS/cm, in Caxiuanã Skirt and the well water 33.2 IJS/cm. The STDs showed a very good statistical correlation with EC, (r=0.996626). In the well water the concentration of STD was 15 mg/L, while in the river waters the values varied from 8 to 12 mg/L and total alkalinity was between 1.14 and 3.42 mg/L. Among the analyzed cations, calcium was the most representative, establishing the sequence for the Ca>Na>K>Mg ions in mg/L and the predominance of the analyzed anions was CI>HC03>S04>SI02 in mg/L. The chemical composition of the studied rivers evidences and interaction between the aqueous environment and the geology of region; the well water is suitable for human consumption.