A presença e o impacto ambiental do nitrato como contaminante emergente em amostras da rede de abastecimento e corpos pluviais na cidade de Pelotas -RS

Abstract

Nitrate is considered an emerging contaminant of global concern, which can impact water quality and pose potential health risks in urban areas, in addition to directly threatening ecosystems when in high concentrations. Nitrate can impact health by causing methemoglobinemia, hypertension, poisoning, severe cyanosis, increased infant mortality, thyroid gland disorders, headaches, hives, cytogenetic defects and congenital malformations, in addition to several types of carcinogenic diseases that are being linked to this contaminant. This study aims to evaluate the concentration of nitrate in samples of water supplies and water bodies of the city of Pelotas - RS, analyzing its environmental impacts and risks to public health. Samples were collected at different points of the city, considering urban areas, classified as supply water, groundwater and wastewater. The analyses were performed by UV-Vis spectrophotometry and ion selective electrode, based on the official methods reported in the Standard Methods for the Examination of Water and Wastewater. The results indicate that groundwater nitrate values exceed the permitted limits, concentrations of 80 mg/L, suggesting contamination by anthropogenic sources. The results obtained had adequate values for accuracy and precision, with recovery tests of 83 and 97% and relative standard deviation below 5%. In view of the above, it is concluded that it was possible to apply the official 4500-NO3- - D methodology for the ion selective electrode in groundwater samples, constituting a viable alternative to ion chromatography for groundwater analysis, offering a simpler and low-cost technique, without compromising the selectivity provided by ion chromatography.