Purpose: The combination of bioremediation and thermal remediation techniques, known as thermally enhanced bioremediation, aims to efficiently remove soil contaminants. However, increasing the temperature in remediation processes can have negative impacts on soil microorganisms. Therefore, we aimed to evaluate the effects of soil heating and naphthalene contamination on soil quality and phytotoxicity variables. Materials and methods: To simulate thermally enhanced bioremediation, soil samples were artificially contaminated with 5 naphthalene concentrations (0, 50, 100, 250 and 500 mg of naphthalene/kg of soil) and incubated at temperatures of 28, 38, 48 and 58 °C. The effects of the factors were determined using microbiological bioindicators (microbial activity and biomass, metabolic quotient and bacterial count on petri dishes), and phytotoxicity (germination and root length of lettuce seeds), assessed immediately and after 15 and 30 days of contamination. For statistical analysis of the bioindicators, multivariate analyses: PERMANOVA (Permutational Multivariate Analysis of Variance) and Principal Component Analysis were applied using software R. Results and discussion: Based on the bioindicators applied, it was found that immediate contamination with naphthalene implied a reduction in biomass and microbial growth associated with greater environmental stress, due to increasing qCO2 values, at high concentrations (250 and 500 mg /kg). Over time (15 and 30 days), an interaction was identified between temperature and contaminant concentration, with a complex effect between these factors, the temperature range between 28 and 38 °C stimulated the growth of microbial communities, regardless of concentration. Conclusion: In this study the results indicate that temperature ranges below 40 °C are promising for application in thermally enhanced bioremediation strategies, as they benefit soil microorganisms and potentially favor contaminant degradation.

The combination of bioremediation and thermal remediation techniques, known as thermally enhanced bioremediation, aims to efficiently remove soil contaminants. However, increasing the temperature in remediation processes can have negative impacts on soil microorganisms. Therefore, we aimed to evaluate the effects of soil heating and naphthalene contamination on soil quality and phytotoxicity variables. To simulate thermally enhanced bioremediation, soil samples were artificially contaminated – with 5 naphthalene concentrations (0, 50, 100, 250 and 500 mg of naphthalene/kg of soil) and incubated at temperatures of 28, 38, 48 and 58 °C. The factors effects were determined using microbiological bioindicators – microbial activity and biomass, metabolic quotient and bacterial count on petri dishes, and phytotoxicity – germination and root length of lettuce seeds, assessed immediately and after 15 and 30 days of contamination. Based on the bioindicators applied, it was found that immediate contamination with naphthalene implied a reduction in biomass and microbial growth associated with greater environmental stress, due to increasing qCO2 values, at high concentrations (250 and 500 mg /kg). The temperature range between 28 and 38 °C stimulated the growth of microbial communities, regardless of concentration. These results indicate that temperature ranges below 40 °C are promising for application in thermally enhanced bioremediation strategies, as they benefit soil microorganisms and potentially favor contaminant degradation.

As trilhas ecológicas são locais que promovem o ecoturismo, objetivando a valorização e sensibilização quanto à preservação e conservação dos recursos naturais. No entanto, muitas trilhas não têm recebido valor por parte dos órgãos ambientais ou proprietários, desmerecendo a sua função ambiental. Muito disso se deve à ausência de mapeamento e caracterização ambiental, também de seus recursos naturais importantes como corpos d´água passíveis de potabilidade e/ou balneabilidade. Nesse sentido, o objetivo do presente estudo foi aplicar ferramentas de geoprocessamento na caracterização ambiental de uma trilha utilizada por romeiros, em Delfim Moreira, sul de Minas Gerais, e avaliar pontos de água de interesse dos usuários quanto à sua potabilidade (consumo humano) e balneabilidade (recreação), por meio de análise microbiológica de coliformes totais e Escherichia coli. Os mapas temáticos gerados foram de localização, vegetação, classificação pelo Índice de Vegetação da Diferença Normalizada (NDVI), hipsométrico, declividade, solos, clima, hidrografia e de áreas de preservação permanente (APP). Os resultados de análise microbiológica da água mostraram que as águas das nascentes que cortam a trilha estão contaminadas com coliformes fecais (E. coli), sendo impróprias para consumo de forma imediata. No entanto, as águas das cachoeiras presentes na trilha apresentaram-se excelentes para atividades recreativas. O mapeamento e caracterização ambiental evidenciou tratar-se de uma trilha em área protegida, com facilidade de acesso e baixo grau de esforço físico dos usuários, paisagem exuberante de Mata Atlântica, com forte apelo turístico e econômico por gestores ambientais e turísticos da região.