ICP-OES Analysis of Metal Concentrations in the Waters of the Preguiças River, Maranhão, Brazil

  Abstract: The surface water of the Preguiças River was analyzed to determine its concentrations of cadmium (Cd), iron (Fe), nickel (Ni) and lead (Pb) and to identify their potential effects on human health and on the environment. Although the mouth of this river is under environmental protection, it is subject to latent anthropogenic exploitation, whose impacts have been only scantily investigated scientifically. Water samples were collected during the rainy and dry seasons, at three different points of the Preguiças River, marked by GPS (Garmin GPSMAP 62sc), as follows: Povoado (village) Marcelinho — P1 (02°48'05.2''S 042°52'14,5''W), Povoado Boa Vista — P2 (02°43'53.6''S 042°46'49.8''W) and the proximities of Vassouras — P3 (02°41'55.7''S 042°43'12.2''W), employing the water sample collection method established by the State of São Paulo Environmental Sanitation Technology Company (CETESB) and EPA Method 200.2 of the United States Environmental Protection Agency for the determination of metals by inductively coupled plasma optical emission spectroscopy (ICP-OES). The results of these analyses were compared with the parameters listed in Resolution 357/05 of Brazil’s National Environmental Agency (CONAMA), in terms of Cd, Fe, Ni and Pb concentrations, most of which exceeded the maximum values allowed for river water at the sampling points in the rainy season. These concentrations in surface water may be the result of soil erosion and the erosion processes typical of the rainy season, as well as ordinary anthropogenic actions such as the burning of fuels.