Impacts of mixed farms on water quality of Pinhal river sub-basin, Santa Catarina, Brazil

brazil is one of the largest producers of food in the world. agriculture and livestock production are concentrated in certain regions of the country. livestock has been perceived as a constant threat to the quantity and quality of water resources. the objective of this study was to evaluate the impact of mixed farms on superficial water quality in pinhal river sub-basin, which is located in concordia, santa catarina state. eight sampling sites representing different land-uses (lu1: dairy cattle; lu2: without animals; lu3: dairy + pigs + poultry + crops; lu4: pigs + poultry + crops; lu5: dairy + pigs + poultry + crops + human; lu6: dairy + pigs + crops; lu7 and lu8: dairy + pigs) were evaluated. these sampling sites were assessed longitudinally and sampled during the summer, spring, autumn, and winter of 2006 to 2009. lu1 presented the worst water quality with high concentrations of total suspended solids (tss) and chemical oxygen demand. in this point, cows had access to the river. the highest concentration of nitrate (no3-n) was found at the estuary of the river. there were higher concentrations of tss, no3-n and no2-n in wet season. at this time, intensive fertilizer application to corn fields is common. autumn and winter presented the worst water quality with respect to nitrogen concentration. results showed a strong relationship between the sources of pollution (e.g., cows, pigs and poultries) and water quality. managing the use of animal manure with optimum chemical fertilizer applications along with riparian fencing may provide important mitigation options for protecting water quality of pinhal river.