The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Ralf Conrad - One of the best experts on this subject based on the ideXlab platform.
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in situ measurement of methane fluxes and analysis of transcribed particulate methane monooxygenase in desert Soils
Environmental Microbiology, 2009Co-Authors: Roey Angel, Ralf ConradAbstract:Summary Aerated Soils are a biological sink for atmospheric methane. However, the activity of desert Soils and the presence of methanotrophs in these Soils have hardly been studied. We studied on-site atmospheric methane consumption rates as well as the diversity and expression of the pmoA gene, coding for a subunit of the particulate methane monooxygenase, in Arid and hyperArid Soils in the Negev Desert, Israel. Methane uptake was only detected in undisturbed Soils in the Arid region (~90 mm year -1 ) and vertical methane profiles in soil showed the active layer to be at 0‐20 cm depth. No methane uptake was detected in the hyperArid Soils (~20 mm year -1 ) as well as in disturbed Soils in the Arid region (i.e. agricultural field and a mini-catchment). Molecular analysis of the methanotrophic community using terminal restriction fragment length polymorphism (T-RFLP) and cloning/ sequencing of the pmoA gene detected methanotrophs in the active Soils, whereas the inactive ones were dominated by sequences of the homologous gene amoA, coding for a subunit of the ammonia monooxygenase. Even in the active Soils, methanotrophs (as well as in situ activity) could not be detected in the soil crust, which is the biologically most important layer in desert Soils. All pmoA sequences belonged to yet uncultured strains. Transcript analysis showed dominance of sequences clustering within the JR3, formerly identified in Californian grassland Soils. Our results show that although active methanotrophs are prevalent in Arid Soils they seem to be absent or inactive in hyperArid and disturbed Arid Soils. Furthermore, we postulate that methanotrophs of the yet uncultured JR3 cluster are the dominant atmospheric methane oxidizers in this ecosystem.
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in situ measurement of methane fluxes and analysis of transcribed particulate methane monooxygenase in desert Soils
Environmental Microbiology, 2009Co-Authors: Roey Angel, Ralf ConradAbstract:Aerated Soils are a biological sink for atmospheric methane. However, the activity of desert Soils and the presence of methanotrophs in these Soils have hardly been studied. We studied on-site atmospheric methane consumption rates as well as the diversity and expression of the pmoA gene, coding for a subunit of the particulate methane monooxygenase, in Arid and hyperArid Soils in the Negev Desert, Israel. Methane uptake was only detected in undisturbed Soils in the Arid region (approximately 90 mm year(-1)) and vertical methane profiles in soil showed the active layer to be at 0-20 cm depth. No methane uptake was detected in the hyperArid Soils (approximately 20 mm year(-1)) as well as in disturbed Soils in the Arid region (i.e. agricultural field and a mini-catchment). Molecular analysis of the methanotrophic community using terminal restriction fragment length polymorphism (T-RFLP) and cloning/sequencing of the pmoA gene detected methanotrophs in the active Soils, whereas the inactive ones were dominated by sequences of the homologous gene amoA, coding for a subunit of the ammonia monooxygenase. Even in the active Soils, methanotrophs (as well as in situ activity) could not be detected in the soil crust, which is the biologically most important layer in desert Soils. All pmoA sequences belonged to yet uncultured strains. Transcript analysis showed dominance of sequences clustering within the JR3, formerly identified in Californian grassland Soils. Our results show that although active methanotrophs are prevalent in Arid Soils they seem to be absent or inactive in hyperArid and disturbed Arid Soils. Furthermore, we postulate that methanotrophs of the yet uncultured JR3 cluster are the dominant atmospheric methane oxidizers in this ecosystem.
Roey Angel - One of the best experts on this subject based on the ideXlab platform.
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in situ measurement of methane fluxes and analysis of transcribed particulate methane monooxygenase in desert Soils
Environmental Microbiology, 2009Co-Authors: Roey Angel, Ralf ConradAbstract:Summary Aerated Soils are a biological sink for atmospheric methane. However, the activity of desert Soils and the presence of methanotrophs in these Soils have hardly been studied. We studied on-site atmospheric methane consumption rates as well as the diversity and expression of the pmoA gene, coding for a subunit of the particulate methane monooxygenase, in Arid and hyperArid Soils in the Negev Desert, Israel. Methane uptake was only detected in undisturbed Soils in the Arid region (~90 mm year -1 ) and vertical methane profiles in soil showed the active layer to be at 0‐20 cm depth. No methane uptake was detected in the hyperArid Soils (~20 mm year -1 ) as well as in disturbed Soils in the Arid region (i.e. agricultural field and a mini-catchment). Molecular analysis of the methanotrophic community using terminal restriction fragment length polymorphism (T-RFLP) and cloning/ sequencing of the pmoA gene detected methanotrophs in the active Soils, whereas the inactive ones were dominated by sequences of the homologous gene amoA, coding for a subunit of the ammonia monooxygenase. Even in the active Soils, methanotrophs (as well as in situ activity) could not be detected in the soil crust, which is the biologically most important layer in desert Soils. All pmoA sequences belonged to yet uncultured strains. Transcript analysis showed dominance of sequences clustering within the JR3, formerly identified in Californian grassland Soils. Our results show that although active methanotrophs are prevalent in Arid Soils they seem to be absent or inactive in hyperArid and disturbed Arid Soils. Furthermore, we postulate that methanotrophs of the yet uncultured JR3 cluster are the dominant atmospheric methane oxidizers in this ecosystem.
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in situ measurement of methane fluxes and analysis of transcribed particulate methane monooxygenase in desert Soils
Environmental Microbiology, 2009Co-Authors: Roey Angel, Ralf ConradAbstract:Aerated Soils are a biological sink for atmospheric methane. However, the activity of desert Soils and the presence of methanotrophs in these Soils have hardly been studied. We studied on-site atmospheric methane consumption rates as well as the diversity and expression of the pmoA gene, coding for a subunit of the particulate methane monooxygenase, in Arid and hyperArid Soils in the Negev Desert, Israel. Methane uptake was only detected in undisturbed Soils in the Arid region (approximately 90 mm year(-1)) and vertical methane profiles in soil showed the active layer to be at 0-20 cm depth. No methane uptake was detected in the hyperArid Soils (approximately 20 mm year(-1)) as well as in disturbed Soils in the Arid region (i.e. agricultural field and a mini-catchment). Molecular analysis of the methanotrophic community using terminal restriction fragment length polymorphism (T-RFLP) and cloning/sequencing of the pmoA gene detected methanotrophs in the active Soils, whereas the inactive ones were dominated by sequences of the homologous gene amoA, coding for a subunit of the ammonia monooxygenase. Even in the active Soils, methanotrophs (as well as in situ activity) could not be detected in the soil crust, which is the biologically most important layer in desert Soils. All pmoA sequences belonged to yet uncultured strains. Transcript analysis showed dominance of sequences clustering within the JR3, formerly identified in Californian grassland Soils. Our results show that although active methanotrophs are prevalent in Arid Soils they seem to be absent or inactive in hyperArid and disturbed Arid Soils. Furthermore, we postulate that methanotrophs of the yet uncultured JR3 cluster are the dominant atmospheric methane oxidizers in this ecosystem.
Refugio Rodríguez-vázquez - One of the best experts on this subject based on the ideXlab platform.
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Assessment of Tannery Waste in Semi-Arid Soils Under a Simulated Rainfall System
Soil and Sediment Contamination: An International Journal, 2014Co-Authors: Martha Barajas-aceves, J. D. Rios-berber, J. L. Oropeza-mota, Refugio Rodríguez-vázquezAbstract:The use of tannery sludge in Arid Soils could be promising due to the high content of organic carbon and nitrogen. However, tannery waste also contains high amounts of Cr and salts that could leach into drainage water in response to rainfall. In order to study the effects of two tannery wastes as organic fertilizers on two types of semi-Arid Soils, simulated rainfall experiments were carried out. Soils collected from under and outside a mesquite tree canopy were amended with fleshing waste and/or tannery sludge and incubated 0 to 6 months prior to being subjected to simulated rainfall. The parameters measured were: infiltration, runoff, soil and Cr losses, and NH4+-N and NO3−-N released after a rainfall event. Results showed that fleshing waste added to Soils from outside the canopy tree was the most effective treatment for decreasing runoff, soil losses, and Cr, NH4+-N and NO3−-N loss in runoff and infiltration, in general. However, the same treatment had the opposite results for soil under the canopy. T...
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Chromium fractionation in semi-Arid Soils amended with chromium and tannery sludge
Journal of hazardous materials, 2006Co-Authors: Martha Barajas-aceves, J. Corona-hernández, Refugio Rodríguez-vázquezAbstract:We studied Cr fractionation in three semi-Arid Soils (cultivated, under-the-canopy, and outside-the-canopy Soils). The Soils were amended with: Cr3+, Cr6+, tannery sludge, Cr3+ + tannery sludge, and Cr6+ + tannery sludge and all Soils were incubated for 30 and 120 days at 25 °C. The Cr in three semi-Arid Soils was fractionated using sequential extraction (Tessier scheme). Data of Cr fractionation were used to find the correlations with microbial activities determined in previous work. The microbial activities: CO2–C evolved, dehydrogenase activity and nitrification were determined in the same Soils amended with the same treatments. Tannery sludge was added at 0.0125 g g−1 soil and Cr3+ or Cr6+ at 250 μg g−1 Soils. After 120 days of incubation, higher values of concentration of Cr were found in the residual fraction in the three Soils amended with all the treatments, except cultivated and outside-the-canopy Soils amended with Cr6+ + tannery. The non-residual fraction tended to decrease with time except in cultivated and outside-the-canopy Soils amended with Cr6+ + tannery sludge. CO2–C evolved was significantly correlated (p < 0.05 and p < 0.001) with fractions bound to: Mn oxides, Fe oxides organic matter at 30 and 120 days of incubation (from r = 0.827 to 0.979). Dehydrogenase activity was correlated with fractions bound to Fe oxides and bound to organic matter, and nitrification with fraction bound to organic matter at 30 days of incubation (r = 0.874, 0.959, and 0.803, respectively). These results suggest that even in a sparingly available Cr fraction in semi-Arid Soils has effect on microbial activities.
R Rodríguez Vázquez - One of the best experts on this subject based on the ideXlab platform.
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Effects of Cr3+, Cr6+ and tannery sludge on C and N mineralization and microbial activity in semi-Arid Soils.
Journal of hazardous materials, 2006Co-Authors: M Barajas Aceves, R Ocampo Velásquez, R Rodríguez VázquezAbstract:The aim of this study was to evaluate the effect of two Cr species (Cr(3+) and Cr(6+)) on N and C mineralization and dehydrogenase activity in semi-Arid Soils. The Cr species (250 mg kg(-1)soil) were either added alone or mixed with tannery sludge (0.0125 g g(-1)) to three Soils: cultivated Soils, and outside and under the canopy of mesquite trees were then incubated for 180 days at 25 degrees C. Sole Cr(6+) addition had a higher inhibition of CO(2) production rate in cultivated soil (58-73%) than in Soils under the canopy and outside the canopy. Soil outside the canopy amended with Cr(6+) showed the highest inhibition of dehydrogenase activity (40-100%) followed by cultivated and under the canopy Soils. However, Cr(6+) added alone increased the inhibition of nitrification in soil outside the canopy (68-84%, from 30 to 120 days), followed by under the canopy and cultivated Soils. The addition of tannery sludge to Cr(6+) significantly reduce the CO(2) production rate and dehydrogenase activity in all three Soils, and increased the inhibition of nitrification in the following order: outside the canopy, cultivated and under the canopy Soils. The addition of Cr(3+) or Cr(3+) plus tannery sludge either stimulated or inhibited CO(2) production rate, dehydrogenate activity and ammonification in the three Soils in no clearly defined order. Measurement of dehydrogenase activity was the best tool for assessing the harmful effect of Cr(6+) on soil microbial activity in semi-Arid Soils exposed for an extended period.
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Effects of Cr3+, Cr6+ and tannery sludge on C and N mineralization and microbial activity in semi-Arid Soils
Journal of Hazardous Materials, 2006Co-Authors: M Barajas Aceves, R Ocampo Velásquez, R Rodríguez VázquezAbstract:Abstract The aim of this study was to evaluate the effect of two Cr species (Cr 3+ and Cr 6+ ) on N and C mineralization and dehydrogenase activity in semi-Arid Soils. The Cr species (250 mg kg −1 soil) were either added alone or mixed with tannery sludge (0.0125 g g −1 ) to three Soils: cultivated Soils, and outside and under the canopy of mesquite trees were then incubated for 180 days at 25 °C. Sole Cr 6+ addition had a higher inhibition of CO 2 production rate in cultivated soil (58–73%) than in Soils under the canopy and outside the canopy. Soil outside the canopy amended with Cr 6+ showed the highest inhibition of dehydrogenase activity (40–100%) followed by cultivated and under the canopy Soils. However, Cr 6+ added alone increased the inhibition of nitrification in soil outside the canopy (68–84%, from 30 to 120 days), followed by under the canopy and cultivated Soils. The addition of tannery sludge to Cr 6+ significantly reduce the CO 2 production rate and dehydrogenase activity in all three Soils, and increased the inhibition of nitrification in the following order: outside the canopy, cultivated and under the canopy Soils. The addition of Cr 3+ or Cr 3+ plus tannery sludge either stimulated or inhibited CO 2 production rate, dehydrogenate activity and ammonification in the three Soils in no clearly defined order. Measurement of dehydrogenase activity was the best tool for assessing the harmful effect of Cr 6+ on soil microbial activity in semi-Arid Soils exposed for an extended period.
Martha Barajas-aceves - One of the best experts on this subject based on the ideXlab platform.
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Assessment of Tannery Waste in Semi-Arid Soils Under a Simulated Rainfall System
Soil and Sediment Contamination: An International Journal, 2014Co-Authors: Martha Barajas-aceves, J. D. Rios-berber, J. L. Oropeza-mota, Refugio Rodríguez-vázquezAbstract:The use of tannery sludge in Arid Soils could be promising due to the high content of organic carbon and nitrogen. However, tannery waste also contains high amounts of Cr and salts that could leach into drainage water in response to rainfall. In order to study the effects of two tannery wastes as organic fertilizers on two types of semi-Arid Soils, simulated rainfall experiments were carried out. Soils collected from under and outside a mesquite tree canopy were amended with fleshing waste and/or tannery sludge and incubated 0 to 6 months prior to being subjected to simulated rainfall. The parameters measured were: infiltration, runoff, soil and Cr losses, and NH4+-N and NO3−-N released after a rainfall event. Results showed that fleshing waste added to Soils from outside the canopy tree was the most effective treatment for decreasing runoff, soil losses, and Cr, NH4+-N and NO3−-N loss in runoff and infiltration, in general. However, the same treatment had the opposite results for soil under the canopy. T...
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Chromium fractionation in semi-Arid Soils amended with chromium and tannery sludge
Journal of hazardous materials, 2006Co-Authors: Martha Barajas-aceves, J. Corona-hernández, Refugio Rodríguez-vázquezAbstract:We studied Cr fractionation in three semi-Arid Soils (cultivated, under-the-canopy, and outside-the-canopy Soils). The Soils were amended with: Cr3+, Cr6+, tannery sludge, Cr3+ + tannery sludge, and Cr6+ + tannery sludge and all Soils were incubated for 30 and 120 days at 25 °C. The Cr in three semi-Arid Soils was fractionated using sequential extraction (Tessier scheme). Data of Cr fractionation were used to find the correlations with microbial activities determined in previous work. The microbial activities: CO2–C evolved, dehydrogenase activity and nitrification were determined in the same Soils amended with the same treatments. Tannery sludge was added at 0.0125 g g−1 soil and Cr3+ or Cr6+ at 250 μg g−1 Soils. After 120 days of incubation, higher values of concentration of Cr were found in the residual fraction in the three Soils amended with all the treatments, except cultivated and outside-the-canopy Soils amended with Cr6+ + tannery. The non-residual fraction tended to decrease with time except in cultivated and outside-the-canopy Soils amended with Cr6+ + tannery sludge. CO2–C evolved was significantly correlated (p < 0.05 and p < 0.001) with fractions bound to: Mn oxides, Fe oxides organic matter at 30 and 120 days of incubation (from r = 0.827 to 0.979). Dehydrogenase activity was correlated with fractions bound to Fe oxides and bound to organic matter, and nitrification with fraction bound to organic matter at 30 days of incubation (r = 0.874, 0.959, and 0.803, respectively). These results suggest that even in a sparingly available Cr fraction in semi-Arid Soils has effect on microbial activities.