Caracterização geoelétrica de subsuperfície através do método da eletrorresistividade do cemitério de Monte Alto (SP)
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Data
2019-03-29
Autores
Donato, Fabio Tosi di
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Universidade Estadual Paulista (Unesp)
Resumo
Os cemitérios atualmente são considerados como potenciais fontes de contaminação, principalmente para as águas subterrâneas. Isso é devido ao líquido produzido durante a decomposição dos cadáveres, denominado necrochorume. Este trabalho investigou uma possível contaminação por necrochorume no subssolo do cemitério da Saudade situado no município de Monte Alto – São Paulo, Brasil. Assim foi aplicado o método da eletrorresistividade, técnica de imageamento elétrico, utilizando três tipos clássicos de arranjos: wernner, schlumberger e dipolo-dipolo. Com o intuito de também comparar os resultados gerados por cada tipo de arranjo. A técnica da sondagem elétrica vertical (SEV) foi utilizada para se indicar a profundidade do nível freático e o fluxo subterrâneo, que foram de 10 m e sentido SW respectivamente. Além da aplicação desses métodos geofísicos, foi realizada uma pesquisa documental nos registros de sepultamentos do cemitério. Obtendo-se um mapa que indica as quadras com maiores números de sepultamentos do cemitério. As seções (2D) resultantes das linhas de imageamento elétrico dos três tipos de arranjo, são muito semelhantes, com algumas poucas diferenças significativas para o arranjo dipolo-dipolo, principalmente em níveis mais profundos. As seções confirmam a presença de áreas de baixa resistividade que contrastam com o restante do meio, indicando possíveis alterações do meio físico causadas pelo necro-chorume. Para visualização em 3D e em mapa, foram confeccionados mapas de vários níveis de profundidade para os resultados de cada arranjo. A sobreposição em mapa dos dados do imageamento elétrico (resistividade), ao mapa de número de sepultamentos por quadra, mostra uma razoável correlação espacial de proximidade entres as anomalias de baixa resistividade, e as quadras de maiores números de sepultamentos. Este trabalho confirma a eficiência do método da eletrorresistividade na investigação ambiental de cemitérios com suspeita de contaminação por necrochorume.
Actually, cemeteries are considered as potential sources of contamination, especially for underground water. This is due to the liquid produced during the decomposition of the corpses, called necrochorume. This work investigated a possible contamination by necro-manure in the subsoil of the Saudade cemetery located in the city of Monte Alto - São Paulo, Brazil. Thus, the method of electro resistivity was applied (eletric resistivity tomography), using three classical types of arrays: wernner, schlumberger and dipole-dipole. In order to also compare the results generated by each type of array. The technique of vertical electric sounding (SEV) was used to indicate the depth of the groundwater and the underground flow, which were 10 m and SW direction respectively. In addition to the application of these geophysical methods, a documentary research was carried out in the book records of the cemetery. Obtaining a map that indicates the blocks with greater numbers of burials of the cemetery. The sections (2D) resulting from the electric resistivity tomography, of the three types of arrays, are very similar, with a few significant differences for the dipole-dipole array, especially at deep levels. The sections confirm the presence of areas of low resistivity that contrast with the rest of environment, indicating possible changes in the physical environment caused by the necro-manure. For 3D and map visualization, maps of various levels of depth were made for the results of each array. The map overlay of the of the resistivity data to the map of number of burials per block, shows a reasonable spatial correlation of proximity between low resistivity anomalies and the blocks with the largest numbers of burials. This work confirms the efficiency of the method of electro resistivity in the environmental investigation of cemeteries with suspected of contamination by necrochorume.
Actually, cemeteries are considered as potential sources of contamination, especially for underground water. This is due to the liquid produced during the decomposition of the corpses, called necrochorume. This work investigated a possible contamination by necro-manure in the subsoil of the Saudade cemetery located in the city of Monte Alto - São Paulo, Brazil. Thus, the method of electro resistivity was applied (eletric resistivity tomography), using three classical types of arrays: wernner, schlumberger and dipole-dipole. In order to also compare the results generated by each type of array. The technique of vertical electric sounding (SEV) was used to indicate the depth of the groundwater and the underground flow, which were 10 m and SW direction respectively. In addition to the application of these geophysical methods, a documentary research was carried out in the book records of the cemetery. Obtaining a map that indicates the blocks with greater numbers of burials of the cemetery. The sections (2D) resulting from the electric resistivity tomography, of the three types of arrays, are very similar, with a few significant differences for the dipole-dipole array, especially at deep levels. The sections confirm the presence of areas of low resistivity that contrast with the rest of environment, indicating possible changes in the physical environment caused by the necro-manure. For 3D and map visualization, maps of various levels of depth were made for the results of each array. The map overlay of the of the resistivity data to the map of number of burials per block, shows a reasonable spatial correlation of proximity between low resistivity anomalies and the blocks with the largest numbers of burials. This work confirms the efficiency of the method of electro resistivity in the environmental investigation of cemeteries with suspected of contamination by necrochorume.
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Palavras-chave
Geofísica, Cemitérios, Necrochorume, Eletrorresistividade, Alteração do meio físico, Geophysics, Cemeteries, Necrochorume, Electrical resistivity, Changes in the physical environment