Avaliação do risco de contaminação da água para consumo humano por derivados de petróleo na bacia do Rio Piracicaba - MG

Abstract

The availability of water resources for human consumption is a challenge in several regions of the world and has intensified because of the contamination of water by human activities, making it unfit for consumption. Contaminated water is considered a public health problem because it exposes the population to substances that cause from varying severity chronic diseases, to death. The main sources of contamination are in places of greater urbanization and industrialization, where there is also the greatest demand for water consumption by the population. One of the most important sources of contamination is activities that use fossil fuels, releasing Petroleum Hydrocarbons (PH) into the environment, and the aquatic ecosystem is considered one of the final destinations of these contaminants that generate adverse health outcomes for all living organisms of the world, including human beings. The hypothesis that we investigated in this work is that the presence of gas stations close to water resources for human consumption may pose a risk of water contamination by PH and routine quality analyzes of these resources are not carried out in order to identify such contaminants. The general objective of this research is to assess the potential of environmental contamination by fuel storage and distribution activities gas stations through the panorama of soil and/or groundwater contamination from 2014 to 2020, obtained from the data made available annually by FEAM, contributing to guide public bodies as to the areas of greatest attention for carrying out water quality analysis focusing on identifying the presence of PH, taking the hydrographic circumscription of the Rio Piracicaba (MG). To achieve the proposed objective, data on environmental licensing and location of "reeller stations, service stations or refueling points, retail system installations, floating fuel stations and aviation fuel sales stations" were obtained through the IDE-Sisema website on period 2014-2020, as well as information on PH contaminated areas made available in FEAM's annual contaminated areas inventory. To assess whether there was an overlap of contamination areas with water catchment sites for human consumption, Fixed Arbitrary Rays (FAR) were defined from the literature, considering the Influence Zone (40 meters), Transport Zone (150 meters), Contribution Zone of low and medium vulnerability (300 meters) and Contribution Zone of high vulnerability (500 meters). Using maps in shapefile format with the geographic coordinates of the projects distribution and contaminated areas, the FAR were inserted and the presence or absence of water use permits, insignificant use and the presence of water bodies around the contaminated areas were evaluated and of the gas stations. Additionally, used in the 100 meter buffer obtained in contaminated areas and from gas stations according to the methodology provided for in Resolução CONAMA Nº23 for comparison purposes. Using maps in shapefile format with geographical coordinates of the gas station and contaminated areas, the RAFs were inserted and the presence or absence of water use permits, insignificant use and the presence of water bodies around the contaminated areas and gas station were evaluated. Water catchments for human consumption was identified around 10 of the 15 HP contaminated areas. In all, 50 abstraction grants and 28 insignificant uses of water for human consumption were present in the sample, but the most worrying in these findings was the volume of catchment up to 150 meters from the contamination, totaling 81.3 m³/day captured without adequate monitoring. for the obvious risk of HP contamination. In the sampling related to gas stations, 438 records of water use permits were observed, distributed in at least one of the buffers in their surroundings, 372 of these records of underground grants and 66 records of superficial grants. The 372 grants for the use of water for human consumption have an average of 6.8 m³/day of abstraction, 96 of them with catchment equal to or less than 1 m³/day, that is, less than 25% of the grants for use of water identified in the sampling correspond to low volume catchment, for probable supply of a single residence. Groundwater abstraction between 1.01 and 10 m³/day are more representative in the sample, corresponding to 262 records, demonstrating that the catchments of water for human consumption identified in the vicinity of gas stations is most likely distributed to several different residences. Regarding the risk classification adopted in the present study, 242 low-risk, 79 medium-risk and 26 high-risk catchments were identified, totaling 4,386 m³/day collected up to 500 meters away from gas stations and 694 m³/ day catchment up to 500 meters from areas contaminated by HP. The surface water bodies were quite representative in the sampling, generating a high number of these water resources in the risk classification, with a total of 345 stretches, with 59 of them classified as high risk, 56 medium risk and 230 low risk of contamination by HP. When evaluating the current monitoring required by the legislation, with the sampling of water in a radius of 100 meters around compared to the 150-meter buffer proposed in this work, a significant increase in water catchment identified with only 50 meters added to the sampling radius and also the volume of water to be monitored in CH DO2. There are uptake of 350.8 m³/day in grants and 54 m³/day in insignificant use present in the 150-meter buffer, while the 100-meter buffer presents uptake of 195.7 m³/day in the grants and 32 m³/day in the insignificant use of water. Therefore, it is suggested to evaluate the quality of water for human consumption identified in the sampling in CH DO2, and it should be considered that the evaluation of the presence of contamination in a water catchment is an indication for the analysis of other catchments in the region to evaluate the possible dispersion of HP contaminants to locations that are not close to gas stations.