Caracterização físico-química e biológica da água e dos solos das margens do rio Piancó, PB.

Abstract

Piancó River’s sub-basin is entirely inserted in the state of Paraíba and its area is of 9.242,75 km². The purpose of this research is to monitor the water and soil quality on the shore of Piancó River and it also aims to define the environmental management measures of this basin. Physical-chemical and microbiological parameters (total coliforms and E.coli) were collected in three sample spots through Piancó River in the countryside of Paraíba (Coremas, Cajazeirinhas and Pombal), and were analyzed on the field with the multi-parameter probe Horiba U22 and in the laboratory comparatively between dry and wet seasons from February to November, 2014. In order to characterize the soil after collection, drying and sieving, the samples were sent to the laboratory and were analyzed physically (granulometry), chemically (pH, exchangeable cations, nutrients and heavy metals), mineralogically (EDX and DRX) and thermally (thermogravimetry). For the purpose of verifying possible contaminations through heavy metals, water and soil samples were examined by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). An analysis was made through semi-structured questionnaires together with 140 dwellers about the use they make of the water and soil. At the same time, hotographic register was made and also a checklist of the principal environmental impacts as:domestic wastewater, solid waste, sand exploitation, agricultural exploitation, deforestation and elephant grass planting in the riverbed. Among the reported main uses for river water are bathing, cooking and doing laundry. Microbiological or sanitary quality of Piancó river water is neither proper for human consumption - if it is not treated -, nor for watering, especially in the sample areas CRM and PBL where water quality meet the criteria recommended by WHO for unrestricted irrigation. The main diseases associated to river water use reported by the population were in the digestive system and skin conditions. Concerning heavy metals there was no overcoming of the limits established by the resolutions of CONAMA numbers 357/2005 and 420/2009 for class II rivers. Soils were characterized as sandy loam, nonsodic, nonsaline, eutrophic (fertile), low CEC and most of it is occupied by calcium and magnesium ions. Concerning mineralogy the principal oxides were SiO2, Al2O3 and Fe2O3, these elements are most found on Earth’s crust besides the high levels of CaO in Coremas. Nitrogen and phosphorus values obtained may be related to the presence of excrement, fertilizers and domestic effluents unload and this indicates local pollution. Therefore, proper soil management measures should be taken.