Controlo da qualidade da água do rio infulene para fins de irrigação

Abstract

In the present work, the water quality of the Infulene River was determined for the purposes of irrigation. The samples were collected at seven points in the river (2 at Lusovinhos, 2 at Fapacar, 1 at 2M, 1 at EHI and 1 at Pontinha-WWTP), in December 2011. For the study, the parameters determined: pH, t a, TDS, CE, color, turbidity, NO 3-, NO 2- and NH 4+ measured at the site sampling by portable devices; CO 32-, HCO 3-, Cl-, COD, Ca and Mg by volume; SO 42- by gravimetry; Ca, Mg, Cu, Fe, Zn, Pb, Mn and K by atomic absorption spectrophotometry with flame atomization (FAAS); Na and K by flame photometry (FC) and fecal and total coliforms by the filter membrane method. Due to the absence of reference material for the control of results, four laboratories (LEM, IIAM, Faculty of Medicine and Chemistry Department of UEM) and different methods of analysis, classic and instrumental. The accuracy in determining the parameters ranged from very good to good with% RSD of 0.00-8.77% with the exception of Ca in LEM to the point F2 where the% RSD was 11.4%. Comparing the averages of the results obtained by various methods as well as by apparatus from different laboratories, it was found that there were significant difference for Ca and Mg. FAO, NP and NAS standards were used to interpret the results on quality water for irrigation purposes. FAO standards were taken as a reference and according to them, it can be said that the water of the river Infulene is of good quality for irrigation purposes, except in the referring to the results of CO 32- and K that are above the recommended limits. CO 32- ions do not have toxic effects on plant development, affecting only the aesthetics of the leaves and fruits and obstruction of the irrigation equipment while the K is a important micronutrient, but leads to rapid and premature plant growth; also has no toxic effects. When the spray irrigation technique is applied according to FAO standards, Cl - have a moderate degree of restriction to none and Na + a degree of moderate restriction. The Fe despite to be above the limit recommended by FAO standards is below the limits recommended by NP and NAS. The values ​​for the turbidity, NO 2-, COD and coliforms parameters will serve as information, given that, from the standards consulted, no values ​​of reference. The values ​​of Cu, Mn and Pb are below the detection limit of the device. There is an irregularity in the variation of the content of the parameters analyzed along the river.