Glyphosate （N-phosphonomethyl glycine） is the most used herbicide worldwide. The degradation of ^14C-labeled glyphosate was studied under controlled laboratory conditions in three different agricultural soils： a si...Glyphosate （N-phosphonomethyl glycine） is the most used herbicide worldwide. The degradation of ^14C-labeled glyphosate was studied under controlled laboratory conditions in three different agricultural soils： a silt clay loam, a clay loam and a sandy loam soil. The kinetic and intensity of glyphosate degradation varied considerably over time within the same soil and among different types of soil. Our results demonstrated that the mineralization rate of glyphosate was high at the beginning of incubation and then decreased with time until the end of the experiment. The same kinetic was observed for the water extractable residues. The degradation of glyphosate was rapid in the soil with low adsorption capacity （clay loam soil） with a short half-life of 4 days. However, the persistence of glyphosate in high adsorption capacity soils increased, with half-live of 19 days for silt clay loam soil and 14.5 days for sandy loam soil. HPLC analyses showed that the main metabolite of glyphosate, arninomethylphosphonic acid （AMPA） was detected after three days of incubation in the extracts of all three soils. Our results suggested that the possibility of contamination of groundwater by glyphosate was high on a long-term period in soils with high adsorption capacity and low degrading activities and/or acid similar to sandy loam soil. This risk might be faster but less sustainable in soil with low adsorption capacity and high degrading activity like the clay loam soil. However, the release of non-extractable residues may increase the risk of contamination of groundwater regardless of the type of soil.展开更多
Objective: To investigate the chemical composition, in vitro antibacterial and antifungal activity of Mentha longifolia L. essential oils using aqueous extract. Methods: Mentha longifolia L. essential oils were extrac...Objective: To investigate the chemical composition, in vitro antibacterial and antifungal activity of Mentha longifolia L. essential oils using aqueous extract. Methods: Mentha longifolia L. essential oils were extracted using hydrodistillation with Clevenger apparatus for 3 h and the yield of the essential oil was calculated. Essential oils were qualitatively and quantitatively analyzed with gas chromatography and gas chromatography-mass spectrometer. For these essential oils, antibacterial and antifungal activity against human pathogens were evaluated. Results: Nineteen chemical constituents representing 99.72% of the essential oil were found, comprising menthone (39.55%), isopulegone (30.49%), eucalyptol (10.38%), and α-terpineol (3.15%);these were major components, and others were minor components. The essential oil showed strong antibacterial activity against Staphylococcus aureus [(35.24 ± 0.13) mm], Enterococcus faecalis [(32.12 ± 0.12) mm] and Bacillus cereus [(30.06 ± 0.04) mm], as well as antifungal activity against Aspergillus flavus [(38.02 ± 0.06) mm], Alternaria alternaria [(35.26 ± 0.12) mm], and Penicillum spp ((34.14 ± 0.02) mm)Conclusions: It seems that the essential oils derived from the Mentha longifolia L. species could be used as a natural source of antimicrobial agents.展开更多
基金DIREN, AERM and DRAF of Lorraine (France) for their financial support
文摘Glyphosate （N-phosphonomethyl glycine） is the most used herbicide worldwide. The degradation of ^14C-labeled glyphosate was studied under controlled laboratory conditions in three different agricultural soils： a silt clay loam, a clay loam and a sandy loam soil. The kinetic and intensity of glyphosate degradation varied considerably over time within the same soil and among different types of soil. Our results demonstrated that the mineralization rate of glyphosate was high at the beginning of incubation and then decreased with time until the end of the experiment. The same kinetic was observed for the water extractable residues. The degradation of glyphosate was rapid in the soil with low adsorption capacity （clay loam soil） with a short half-life of 4 days. However, the persistence of glyphosate in high adsorption capacity soils increased, with half-live of 19 days for silt clay loam soil and 14.5 days for sandy loam soil. HPLC analyses showed that the main metabolite of glyphosate, arninomethylphosphonic acid （AMPA） was detected after three days of incubation in the extracts of all three soils. Our results suggested that the possibility of contamination of groundwater by glyphosate was high on a long-term period in soils with high adsorption capacity and low degrading activities and/or acid similar to sandy loam soil. This risk might be faster but less sustainable in soil with low adsorption capacity and high degrading activity like the clay loam soil. However, the release of non-extractable residues may increase the risk of contamination of groundwater regardless of the type of soil.
文摘Objective: To investigate the chemical composition, in vitro antibacterial and antifungal activity of Mentha longifolia L. essential oils using aqueous extract. Methods: Mentha longifolia L. essential oils were extracted using hydrodistillation with Clevenger apparatus for 3 h and the yield of the essential oil was calculated. Essential oils were qualitatively and quantitatively analyzed with gas chromatography and gas chromatography-mass spectrometer. For these essential oils, antibacterial and antifungal activity against human pathogens were evaluated. Results: Nineteen chemical constituents representing 99.72% of the essential oil were found, comprising menthone (39.55%), isopulegone (30.49%), eucalyptol (10.38%), and α-terpineol (3.15%);these were major components, and others were minor components. The essential oil showed strong antibacterial activity against Staphylococcus aureus [(35.24 ± 0.13) mm], Enterococcus faecalis [(32.12 ± 0.12) mm] and Bacillus cereus [(30.06 ± 0.04) mm], as well as antifungal activity against Aspergillus flavus [(38.02 ± 0.06) mm], Alternaria alternaria [(35.26 ± 0.12) mm], and Penicillum spp ((34.14 ± 0.02) mm)Conclusions: It seems that the essential oils derived from the Mentha longifolia L. species could be used as a natural source of antimicrobial agents.
