Avaliação físico-química, microbiológica e fatores de influência na qualidade da água em poços residenciais no município de Laranjal do Jari, Amapá, Brasil,

Abstract

To guarantee the quality of the water used in wells, it is necessary to meet the physical, chemical and microbiological standards of potability and some technical criteria of infrastructure and location of the wells. The municipality of Laranjal do Jari, Amapá, does not have a domestic sewage collection network, thus stimulating the intensive construction of rudimentary cesspools, which is the main factor of contamination of underground water bodies. In this context, this study aimed to evaluate the quality of groundwater collected from residential wells and relate it to the distance from septic tanks and infrastructure conditions for the construction of wells in two neighborhoods in the municipality. For this, water samples were collected from ten wells in the Agreste and Nova Esperança neighborhoods. The samples were evaluated using physical-chemical and microbiological parameters (turbidity, conductivity, pH, presence or absence of total coliforms and Escherichia coli) and the results were compared with the limits established by PRC nº 888/2021 of the Ministry of Health. A structured interview was carried out with the owners of the residences to gather information on water use and well infrastructure, and the distance between the wells and the surrounding pits was measured. A Principal Component Analysis (PCA) was carried out to verify correlations between the results of the physical-chemical analyzes and some factors that influence quality. The result of the microbiological analysis resulted in the absence of microorganisms. As for the physical-chemical parameters, four wells were outside the standards for turbidity (>1 UT), and all wells analyzed had high Electrical Conductivity (>100 µS/cm-1), and pH with an average of 3.9 characterizing acidic water and outside the limits established by law. Most of the wells in the Nova Esperança neighborhood had worse conditions because they had water with greater conductivity, higher pH, shallower wells and distances from the wells to smaller cesspits, in relation to what was analyzed in the Bairro Agreste. Thus, it can be inferred that the underground water resource captured in the analyzed neighborhoods is not suitable for human consumption according to the quality standards established by current legislation.