Inter-annual variability on the water quality in the Lower São Francisco River (NE-Brazil)

摘要: Aim This study characterized the water quality in lower Sao Francisco River (NE-Brazil).This research represents first work to be carried out sector of river aiming quantify and compare limnological variables, during three different years (2001, 2004 2007). Methods Water samples were collected a transversal section at monthly intervals period on surface layer. Temperature, conductivity, pH, dissolved oxygen obtained using multiparameter probe YSI-6600. The inorganic nutrients (ammonium, nitrite, nitrate, phosphorus silicates), chlorophyll-a total suspended sediment (TSS) also determined. Results hydrological showed differences precipitation rates discharge conditions. year 2001 had below historical series rainfall. mean annual temperature negligible among years. Dissolved nutrient concentrations highest 2004, with ammonia nitrate differing statistically between (p<0.05); later largest concentration nitrogen. Chlorophyll-a slight difference Conclusions Precipitation intensity has direct impact discharge, but geographical distribution is determinant factor for alterations chemical physical characteristics that reaches River.