Loss of macronutrients (N, P, K) in the hydrographic basin of the River Ivaí, an affluent of the River Paraná

Abstract

Influence of some environmental variables in the loss of macronutrients N, P, K, from the hydrographic basin of the River Ivaí were analysed. Water samples of the river were monthly collected for five consecutive days during a year. In terms of total intervals of average monthly values and total average values experiment results, in mg L-1, were: N (0.32-3.22 and 1.65); K (0.73-2.69 and 1.38); P (not detected-0.39 and 0.076); COD (0.21-36.0 and 12.8); O2(dis) (1.89-8.40 and 5.43); and temperature (ºC) (16.0-30.8 and 24.6); pH (5.18-8.50 and 7.15). Statistical analysis of data showed that quantity of macronutrient (N, K, P) carried off from the hydrographic basin of the River Ivaí were directly correlated to fluviometric levels (caused by rainfall and floodings) at 5% level of significance. Carried off quantities, in t a-1, were N = 25,136.0; K = 21,010.0 and P = 1,161.2.