Physicochemical and chemical variables from water environments were investigated in an area of upland primary forest, near an urban area, in the municipality of Manaus. The investigated surface water streams drain both primary forest and urbanized areas, and are called igarapés in the region. The headwaters of two of these streams are in the urban area, and they run to the forest area and join to make up another stream, and later are joined with another stream which headwaters are located inside the primary forest. This study encompassed the following environmental variables: pH, water electrical conductivity, Na+, K+, Ca2+, Mg2+ and Fe2+ cations and suspended material. It was possible to see significant differences in the concentration of hydrogen ions, electrical conductivity and in the suspended material content, among the studied streams. In the stream in which the headwaters are within the reserve, the mean values corresponding to pH, electrical conductivity and suspended material were 4.47; 6.44 mS cm-1 and 1.25 mg L-1, respectively; and the highest values found in the impacted ones were 6.84, 141.50 mS cm-1 and 9.50 mg L-1. The results show that the stream which drains the forest area maintains its natural characteristics as it is protected from human activities, and the ones which come from the urban area are impacted.
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