Nitrato nas águas subterrâneas de fortaleza: ocorrencias, causas e riscos a saúde da população

Abstract

The nitrate ion is one of the parameters used worldwide as an indicator of groundwater contamination, mainly due to its properties of high mobility and persistence in groundwater, with the capacity to contaminate large areas, with the lack of basic sanitation as the main source of contamination. The Municipality of Fortaleza, located in the coastal zone of the northeast portion of the State of Ceará, covering 313.8 km2 and with 2,686,612 inhabitants, has presented in recent years (1998 to 2018) a rapid urban growth, however, investments in garbage collection and, mainly, in basic sanitation, did not accompany such growth, with inadequate waste disposal being common, and according to data collected by the National Sanitation Information System (SNIS), the sanitation coverage rate is 50 %, forcing a portion of the population to resort to the use of septic tanks, generating potential sources of nitrate contamination in groundwater. Therefore, with the aim of evaluating the occurrences and causes of nitrate concentrations in groundwater, as well as the temporal behavior of concentrations associated with health risks for the population of Fortaleza that uses these waters for human consumption, 40 physical-analyses were carried out. chemicals having as a reference the potability standards for human consumption established by Ordinance No. 888, of May 4, 2021, where it was possible to observe that the groundwater is slightly acidic, with an average pH of 6, with 18 samples outside the standards of potability, in relation to Total Dissolved Solids (TDS) 03 samples are found outside the standards and in the chloride ion, two samples located in the southern portion of the area presented concentrations outside the standards of potability. Regarding nitrogenous compounds, nitrite did not show concentrations outside the standards, but ammonia (02 samples) and nitrate (16 samples) showed values above the Maximum Allowed Value – VMP. Such concentrations, above the maximum limit of the standard established by the Ordinance, bring risks to the health of the population where, according to DATASUS (2021), an average of 4,634 hospitalizations correlated with waterborne diseases are registered annually, with the younger population (0 to 14 years) the one that suffers the most, with 3,821 admissi