Effects of chronic exposure to hexavalent chromium in water on oxidative stress parameters in Wistar rats

Hexavalent chromium [Cr (VI)] is a metal utilized in different industries and consequently disposed in the environment. It is a toxic substance and its reduction to trivalent Cr [Cr (III)] generates intermediates, which are responsible for the oxidation of molecules, and cause the oxidative stress. Therefore, the aim of this study was to evaluate if Cr (VI) could induce oxidative stress in Wistar rats. In this study, Wistar rats were chronically exposed to 25 and 50 ppm of potassium dichromate in drinking water for 30 days. The levels of Cr were evaluated in the blood and tissues (liver, kidneys, and lungs). Oxidative stress was determined in the liver, kidneys, and lungs and was evaluated by DFCH, TBA-RS and carbonyl test. Antioxidant enzymes were evaluated through catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities. Regarding the results, Cr concentration was significantly elevated in all tissues, however, it was lower in the lungs. In relation to the oxidative stress parameters, there was a significant increase of DCFH levels in the kidneys and carbonyls in liver and kidneys. Regarding the antioxidant enzymes, SOD was decreased in all organs and GPx was diminished in the kidneys. These data indicated that Cr (VI) could induce oxidative stress in the kidneys and liver due to an imbalance between oxidative and antioxidant parameters. The lungs were little affected, possibly by the lowest chromium accumulation.

Effects of chronic exposure to hexavalent chromium in water on oxidative stress parameters in Wistar rats

Hexavalent chromium [Cr (VI)] is a metal utilized in different industries and consequently disposed in the environment. It is a toxic substance and its reduction to trivalent Cr [Cr (III)] generates intermediates, which are responsible for the oxidation of molecules, and cause the oxidative stress. Therefore, the aim of this study was to evaluate if Cr (VI) could induce oxidative stress in Wistar rats. In this study, Wistar rats were chronically exposed to 25 and 50 ppm of potassium dichromate in drinking water for 30 days. The levels of Cr were evaluated in the blood and tissues (liver, kidneys, and lungs). Oxidative stress was determined in the liver, kidneys, and lungs and was evaluated by DFCH, TBA-RS and carbonyl test. Antioxidant enzymes were evaluated through catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities. Regarding the results, Cr concentration was significantly elevated in all tissues, however, it was lower in the lungs. In relation to the oxidative stress parameters, there was a significant increase of DCFH levels in the kidneys and carbonyls in liver and kidneys. Regarding the antioxidant enzymes, SOD was decreased in all organs and GPx was diminished in the kidneys. These data indicated that Cr (VI) could induce oxidative stress in the kidneys and liver due to an imbalance between oxidative and antioxidant parameters. The lungs were little affected, possibly by the lowest chromium accumulation.(AU)

Agronomic and environmental implications of using a By-Product of the Intermediate Tanning Processes as Nitrogen Fertilizer

Nitrogen (N) is an important nutrient for agriculture, and Brazil is heavily dependent on N imports. A by-product of the intermediate processes of tanning (BPIPT) may be used as an N fertilizer which will reduce this dependency, but its chromium (Cr) content is a matter of concern. This work assessed Cr (III, VI) and N (total, inorganic) contents in four soil samples with contrasting characteristics (especially with respect to their content of manganese (Mn), a potential Cr(III) oxidant), following the addition of the BPIPT. Chemical and microbiological indicators of soil quality were measured to assess the agronomic and environmental implications of the BPIPT addition in Brazilian soils. Our results indicate that the BPIPT is a promising source of N. The originally available Mn content in the soil did not influence the effect of the BPIPT on soil Cr(VI) content. Finally, microbial activity was generally stimulated after BPIPT addition to the soil. This information is relevant because: 1) it shows that the beneficial use of the BPIPT as an N fertilizer is important for adding value to a by-product with agronomic potential; and 2) it indicates that, at the dosage of the BPIPT used in this study (2.5 g kgsoil-1), the typical increases in the soil concentration of labile Cr (0-25 mg kgsoil-1) and Cr(VI) (0-0.8 mg kgsoil-1) due to the application of the BPIPT are not detrimental to biological activity in the soil. However, further investigations are still necessary to evaluate the mobility of these Cr species in the soil and possible risks of groundwater contamination, which were not addressed in this study.

Agronomic and environmental implications of using a By-Product of the Intermediate Tanning Processes as Nitrogen Fertilizer

Nitrogen (N) is an important nutrient for agriculture, and Brazil is heavily dependent on N imports. A by-product of the intermediate processes of tanning (BPIPT) may be used as an N fertilizer which will reduce this dependency, but its chromium (Cr) content is a matter of concern. This work assessed Cr (III, VI) and N (total, inorganic) contents in four soil samples with contrasting characteristics (especially with respect to their content of manganese (Mn), a potential Cr(III) oxidant), following the addition of the BPIPT. Chemical and microbiological indicators of soil quality were measured to assess the agronomic and environmental implications of the BPIPT addition in Brazilian soils. Our results indicate that the BPIPT is a promising source of N. The originally available Mn content in the soil did not influence the effect of the BPIPT on soil Cr(VI) content. Finally, microbial activity was generally stimulated after BPIPT addition to the soil. This information is relevant because: 1) it shows that the beneficial use of the BPIPT as an N fertilizer is important for adding value to a by-product with agronomic potential; and 2) it indicates that, at the dosage of the BPIPT used in this study (2.5 g kgsoil-1), the typical increases in the soil concentration of labile Cr (0-25 mg kgsoil-1) and Cr(VI) (0-0.8 mg kgsoil-1) due to the application of the BPIPT are not detrimental to biological activity in the soil. However, further investigations are still necessary to evaluate the mobility of these Cr species in the soil and possible risks of groundwater contamination, which were not addressed in this study.(AU)

Hexavalent chromium reduction by aerobic heterotrophic bacteria indigenous to chromite mine overburden

Microbiological analysis of overburden samples collected from chromite mining areas of Orissa, India revealed that they are rich in microbial density as well as diversity and dominated by Gramnegative (58%) bacteria. The phenotypically distinguishable bacterial isolates (130) showed wide degree of tolerance to chromium (2-8 mM) when tested in peptone yeast extract glucose agar medium. Isolates (92) tolerating 2 mM chromium exhibited different degrees of Cr+6 reducing activity in chemically defined Vogel Bonner (VB) broth and complex KSC medium. Three potent isolates, two belonging to Arthrobacter spp. and one to Pseudomonas sp. were able to reduce more than 50 and 80% of 2 mM chromium in defined and complex media respectively. Along with Cr+6 (MIC 8.6-17.8 mM), the isolates showed tolerance to Ni+2, Fe+3, Cu+2 and Co+2 but were extremely sensitive to Hg+2 followed by Cd+2, Mn+2 and Zn+2. In addition, they were resistant to antibiotics like penicillin, methicillin, ampicillin, neomycin and polymyxin B. During growth under shake-flask conditions, Arthrobacter SUK 1201 and SUK 1205 showed 100% reduction of 2 mM Cr+6 in KSC medium with simultaneous formation of insoluble precipitates of chromium salts. Both the isolates were also equally capable of completely reducing the Cr+6 present in mine seepage when grown in mine seepage supplemented with VB concentrate.(AU)

Germination and sporophytic development of Regnellidium diphyllum Lindman (Marsileaceae) in the presence of hexavalent chromium

Regnellidium diphyllum Lindman is a heterosporous fern, growing in aquatic environments and surrounding wetlands, which is assumed to be threatened by increasing water pollution and disappearance of its natural habitats. Among contaminants, hexavalent chromium - Cr(VI) - is known to be present in effluents from some leather tanning factories. Megaspore germination tests were performed using Meyer's solution, at concentrations 0 (control), 0.1, 0.5, 1, 5, 10, 15, 20, 30, 50, and 80 mg.L-1, from a standard solution of Titrisol® 1000 mg.L-1. The primary development of apomictic sporophytes was studied using solutions containing 0.025 to 4.8 mg.L-1 of Cr(VI). The experiments were conducted in a growth chamber at 24 ± 1 ºC and for a 12-hour photoperiod under fluorescent lights, providing a nominal irradiance of 77 µmol.m-2/s. Significant differences in megaspore germination, with subsequent sporophytic development, were verified from 0.5 mg.L-1 Cr(VI) concentration onwards. Growth of primary root and primary and secondary leaves was significantly reduced at 3.2 mg.L-1 Cr(VI) concentration or higher. Considering the pollution from Cr(VI) in some areas of R. diphyllum natural occurrence, these data indicate that low reproductive rates and disappearance of populations are likely to occur in these situations.

Regnellidium diphyllum Lindman é uma filicínea heterosporada que se desenvolve em ambientes aquáticos e áreas úmidas circundantes, sendo considerada ameaçada pelo aumento da poluição e desaparecimento dos seus hábitats naturais. Entre os contaminantes, o cromo hexavalente - Cr(VI) - é conhecido por estar presente nos efluentes de algumas indústrias de curtimento de couro. Testes de germinação foram realizados em meio líquido de Meyer, com concentrações de 0(controle); 0,1; 0,5; 1; 5; 10; 15; 20; 30; 50; e 80 mg.L-1 de Cr(VI), a partir de uma solução padrão de Titrisol® a 1000 mg.L-1. O desenvolvimento primário dos esporófitos apomíticos foi analisado em meios contendo de 0,025 a 4,8 mg.L-1 de Cr(VI). Os experimentos foram conduzidos em câmara de crescimento a 24 ± 1 ºC, fotoperíodo de 12 horas com lâmpadas fluorescentes fornecendo irradiância nominal de 77 µmol.m-2/s. Diferenças significativas na germinação dos megásporos e seu subsequente desenvolvimento foram verificadas a partir da concentração 0,5 mg.L-1 de Cr(VI). O crescimento da raiz primária e das folhas primárias e secundárias foi significativamente reduzido na concentração 3,2mg.L-1 de Cr(VI) ou superior. Considerando a poluição proveniente por Cr(VI) em algumas áreas de ocorrência natural de R. diphyllum, esses dados indicam que as baixas taxas de reprodução e mesmo o desaparecimento das populações podem ser esperadas nessas situações.

Germination and sporophytic development of Regnellidium diphyllum Lindman (Marsileaceae) in the presence of hexavalent chromium

Regnellidium diphyllum Lindman is a heterosporous fern, growing in aquatic environments and surrounding wetlands, which is assumed to be threatened by increasing water pollution and disappearance of its natural habitats. Among contaminants, hexavalent chromium - Cr(VI) - is known to be present in effluents from some leather tanning factories. Megaspore germination tests were performed using Meyer's solution, at concentrations 0 (control), 0.1, 0.5, 1, 5, 10, 15, 20, 30, 50, and 80 mg.L-1, from a standard solution of Titrisol® 1000 mg.L-1. The primary development of apomictic sporophytes was studied using solutions containing 0.025 to 4.8 mg.L-1 of Cr(VI). The experiments were conducted in a growth chamber at 24 ± 1 ºC and for a 12-hour photoperiod under fluorescent lights, providing a nominal irradiance of 77 µmol.m-2/s. Significant differences in megaspore germination, with subsequent sporophytic development, were verified from 0.5 mg.L-1 Cr(VI) concentration onwards. Growth of primary root and primary and secondary leaves was significantly reduced at 3.2 mg.L-1 Cr(VI) concentration or higher. Considering the pollution from Cr(VI) in some areas of R. diphyllum natural occurrence, these data indicate that low reproductive rates and disappearance of populations are likely to occur in these situations.

Regnellidium diphyllum Lindman é uma filicínea heterosporada que se desenvolve em ambientes aquáticos e áreas úmidas circundantes, sendo considerada ameaçada pelo aumento da poluição e desaparecimento dos seus hábitats naturais. Entre os contaminantes, o cromo hexavalente - Cr(VI) - é conhecido por estar presente nos efluentes de algumas indústrias de curtimento de couro. Testes de germinação foram realizados em meio líquido de Meyer, com concentrações de 0(controle); 0,1; 0,5; 1; 5; 10; 15; 20; 30; 50; e 80 mg.L-1 de Cr(VI), a partir de uma solução padrão de Titrisol® a 1000 mg.L-1. O desenvolvimento primário dos esporófitos apomíticos foi analisado em meios contendo de 0,025 a 4,8 mg.L-1 de Cr(VI). Os experimentos foram conduzidos em câmara de crescimento a 24 ± 1 ºC, fotoperíodo de 12 horas com lâmpadas fluorescentes fornecendo irradiância nominal de 77 µmol.m-2/s. Diferenças significativas na germinação dos megásporos e seu subsequente desenvolvimento foram verificadas a partir da concentração 0,5 mg.L-1 de Cr(VI). O crescimento da raiz primária e das folhas primárias e secundárias foi significativamente reduzido na concentração 3,2mg.L-1 de Cr(VI) ou superior. Considerando a poluição proveniente por Cr(VI) em algumas áreas de ocorrência natural de R. diphyllum, esses dados indicam que as baixas taxas de reprodução e mesmo o desaparecimento das populações podem ser esperadas nessas situações.

Germination and sporophytic development of Regnellidium diphyllum Lindman (Marsileaceae) in the presence of hexavalent chromium / Germinação e desenvolvimento esporofítico de Regnellidium diphyllum Lindman (Marsileaceae) na presença de cromo hexavalente

Regnellidium diphyllum Lindman is a heterosporous fern, growing in aquatic environments and surrounding wetlands, which is assumed to be threatened by increasing water pollution and disappearance of its natural habitats. Among contaminants, hexavalent chromium - Cr(VI) - is known to be present in effluents from some leather tanning factories. Megaspore germination tests were performed using Meyer's solution, at concentrations 0 (control), 0.1, 0.5, 1, 5, 10, 15, 20, 30, 50, and 80 mg.L-1, from a standard solution of Titrisol® 1000 mg.L-1. The primary development of apomictic sporophytes was studied using solutions containing 0.025 to 4.8 mg.L-1 of Cr(VI). The experiments were conducted in a growth chamber at 24 ± 1 ºC and for a 12-hour photoperiod under fluorescent lights, providing a nominal irradiance of 77 µmol.m-2/s. Significant differences in megaspore germination, with subsequent sporophytic development, were verified from 0.5 mg.L-1 Cr(VI) concentration onwards. Growth of primary root and primary and secondary leaves was significantly reduced at 3.2 mg.L-1 Cr(VI) concentration or higher. Considering the pollution from Cr(VI) in some areas of R. diphyllum natural occurrence, these data indicate that low reproductive rates and disappearance of populations are likely to occur in these situations.

Regnellidium diphyllum Lindman é uma filicínea heterosporada que se desenvolve em ambientes aquáticos e áreas úmidas circundantes, sendo considerada ameaçada pelo aumento da poluição e desaparecimento dos seus hábitats naturais. Entre os contaminantes, o cromo hexavalente - Cr(VI) - é conhecido por estar presente nos efluentes de algumas indústrias de curtimento de couro. Testes de germinação foram realizados em meio líquido de Meyer, com concentrações de 0(controle); 0,1; 0,5; 1; 5; 10; 15; 20; 30; 50; e 80 mg.L-1 de Cr(VI), a partir de uma solução padrão de Titrisol® a 1000 mg.L-1. O desenvolvimento primário dos esporófitos apomíticos foi analisado em meios contendo de 0,025 a 4,8 mg.L-1 de Cr(VI). Os experimentos foram conduzidos em câmara de crescimento a 24 ± 1 ºC, fotoperíodo de 12 horas com lâmpadas fluorescentes fornecendo irradiância nominal de 77 µmol.m-2/s. Diferenças significativas na germinação dos megásporos e seu subsequente desenvolvimento foram verificadas a partir da concentração 0,5 mg.L-1 de Cr(VI). O crescimento da raiz primária e das folhas primárias e secundárias foi significativamente reduzido na concentração 3,2mg.L-1 de Cr(VI) ou superior. Considerando a poluição proveniente por Cr(VI) em algumas áreas de ocorrência natural de R. diphyllum, esses dados indicam que as baixas taxas de reprodução e mesmo o desaparecimento das populações podem ser esperadas nessas situações.

Adição de cromo hexavalente no crescimento, nodulação e absorção de nutrientes em soja

This study was carried out to evaluate the effect of hexavalent chromium on dry matter production, nutrient uptake and nitrogen fixation in soybeans (Glycine max ) The seeds were inoculated with comercial strains of Bradyrhizobium japonicum (SEMIA 587 and 5019) and the plants were grown in "Leonard Jars" containing washed sand in the upper portion and nutrient solution (without N) in the lower. Five Cr6+ concentrations were used: 0, 5, 10, 20 e 40mg img src="http:/img/fbpe/cr/v31n6/a08img01.gif"> -1 in the nutrient solution. Concentrations of Cr6+ above 5mg img src="http:/img/fbpe/cr/v31n6/a08img01.gif"> -1 decreased plants and nodules dry matter production, number of nodules, nitrogen fixation and P, K, Ca e Mg uptake. Chromium concentrations in soybean tops above 3,4mg kg-1 were considered phytotoxic.

Foram avaliados os efeitos de doses crescentes de Cr6+ sobre a produção de matéria seca, absorção de nutrientes e fixação biológica de nitrogênio em plantas de soja. Antes da semeadura, as sementes foram tratadas com inóculo turfoso contendo Bradyrhizobium japonicum. As plantas foram cultivadas durante 40 dias em vasos "Leonard" que continha areia na parte superior e solução nutritiva sem nitrogênio na parte inferior. Os tratamentos constaram das seguintes doses de Cr6+ (K2Cr2O7) na solução nutritiva: 0, 5, 10, 20 e 40mg img src="http:/img/fbpe/cr/v31n6/a08img01.gif"> -1. Foi constatado que concentrações de Cr6+ maiores que 5mg img src="http:/img/fbpe/cr/v31n6/a08img01.gif"> -1 diminuíram a produção de matéria seca da parte aérea e radicular da soja, o número e peso de nódulos secos de Bradyrhizobium, como também a fixação biológica de nitrogênio e a absorção de P, K, Ca e Mg. Teores de Cr na parte aérea de plantas de soja superiores a 3,4mg Kg-1 podem ser considerados fitotóxicos.

Adição de cromo hexavalente no crescimento, nodulação e absorção de nutrientes em soja

This study was carried out to evaluate the effect of hexavalent chromium on dry matter production, nutrient uptake and nitrogen fixation in soybeans (Glycine max ) The seeds were inoculated with comercial strains of Bradyrhizobium japonicum (SEMIA 587 and 5019) and the plants were grown in "Leonard Jars" containing washed sand in the upper portion and nutrient solution (without N) in the lower. Five Cr6+ concentrations were used: 0, 5, 10, 20 e 40mg img src="http:/img/fbpe/cr/v31n6/a08img01.gif"> -1 in the nutrient solution. Concentrations of Cr6+ above 5mg img src="http:/img/fbpe/cr/v31n6/a08img01.gif"> -1 decreased plants and nodules dry matter production, number of nodules, nitrogen fixation and P, K, Ca e Mg uptake. Chromium concentrations in soybean tops above 3,4mg kg-1 were considered phytotoxic.

Foram avaliados os efeitos de doses crescentes de Cr6+ sobre a produção de matéria seca, absorção de nutrientes e fixação biológica de nitrogênio em plantas de soja. Antes da semeadura, as sementes foram tratadas com inóculo turfoso contendo Bradyrhizobium japonicum. As plantas foram cultivadas durante 40 dias em vasos "Leonard" que continha areia na parte superior e solução nutritiva sem nitrogênio na parte inferior. Os tratamentos constaram das seguintes doses de Cr6+ (K2Cr2O7) na solução nutritiva: 0, 5, 10, 20 e 40mg img src="http:/img/fbpe/cr/v31n6/a08img01.gif"> -1. Foi constatado que concentrações de Cr6+ maiores que 5mg img src="http:/img/fbpe/cr/v31n6/a08img01.gif"> -1 diminuíram a produção de matéria seca da parte aérea e radicular da soja, o número e peso de nódulos secos de Bradyrhizobium, como também a fixação biológica de nitrogênio e a absorção de P, K, Ca e Mg. Teores de Cr na parte aérea de plantas de soja superiores a 3,4mg Kg-1 podem ser considerados fitotóxicos.

Avaliação higiênico-sanitária, teores de nitrato, nitrito e cromo em águas de propriedades rurais e suburbanas em Franca, SP, Brasil / Hygienical-sanitary evaluation, nitrate, nitrito and chromium in waters of properties rural and suburban in Franca, SP, Brazil

Foram avaliadas amostras da água de poços e minas, consumida pela população rural e suburbana em município com atividades agrícolas e industriais no ramo coureiro-calçadista. Ao todo, 372 amostras foram colhidas seguindo normas internacionais em 31 propriedades rurais e 30 suburbanas, localizadas ao longo dos rios que atravessam a área industrial do município, sendo submetidas a exames de detecção de coliformes totais, fecais, mesófilos, enterococos, dosagens de nitrato, nitrito, cromo trivalente e hexavalente (poluentes de efluentes de curtumes). As colheitas foram realizadas em períodos de estiagem (inverno) e repetidas no período de chuvas (verão).Resultados: os parâmetros avaliados de cada período do ano foram comparados com os limites estabelecidos pela legislação vigente. Entre as propriedades rurais, 77,4 por cento das amostras estavam fora dos padrões normais para consumo humano durante o período de estiagem e 70 por cento das amostras no período de chuvas. Já entre as amostras colhidas em propriedades suburbanas, 90 por cento encontravam-se fora dos padrões no período de estiagem e 96,7 por cento no período de chuvas.(AU)

The target of this research was to assess the hygienic-sanitary conditions of drinking water from shallow wells ormines, consumed by the population of rural and suburban zones near the city The microbiological parameters usedwere: total coliforms, fecal coliforms, enterococci, mesophyl microorganisms. The chemical parameters: dosages of nitrates, nitrites, total chromium and hexavalent chromium, the two last are considered as pollutants in tannery effluents. The water samples were collected according to international rules adopted in the country in opposite seasonal conditions: the rainy season (summer) and during the dry season (winter). A total of 31 rural properties and 30 suburban ones were visited. The main conclusions were: the quality of the water can vary according to the season and the source used; shallow wells suffered a significant interference, while spring waters did not; among the microbiologic parameters mesophyl microorganisms suffered a higher increase in all collecting points; among chemical parameters nitrates, total chromium and hexavalent chromium contents suffered a significant increase after the rains, but in none of the properties or collecting points the levels obtained were over the permitted. The situation suggests that the continuous consumption can promote intoxication to the rural and suburban population. (AU)