Threatened or near threatened hydrophytes, <em>Ottelia alismoides</em>, <em>Monochoria korsakowii</em>, <em>Najas graminea</em>, <em>Najas minor</em> and <em>Chara...Threatened or near threatened hydrophytes, <em>Ottelia alismoides</em>, <em>Monochoria korsakowii</em>, <em>Najas graminea</em>, <em>Najas minor</em> and <em>Chara braunii</em>, appeared in an inundated paddy field after the 2011 Tohoku-oki Tsunami in Japan. Due to the reconstruction of roads and agricultural restoration efforts implemented following the disaster, the top soil of the paddy field was transplanted to another abandoned paddy field in 2014 to avoid extirpation of the aforementioned species. We then conducted vegetation surveys in July and September from 2014 to 2016. <em>Monochoria korsakowii</em> appeared at the transplantation site from 2014 to 2016, forming a large community in 2016. The volume of this species was significantly higher than that in July 2014 and 2015. Although <em>Ottelia alismoides</em> and<em> Chara braunii</em> appeared in 2014, they were not observed in 2015. <em>Najas graminea</em> and<em> Najas minor</em> were not observed during the vegetation survey, and<em> Salvinia natans</em> and<em> Alisma plantago-aquatica</em> newly appeared at the transplantation site. Our findings suggest that transplantation of surface soil and the seed bank therein to an abandoned paddy field is well suited for the conservation of hygrophytes such as <em>Monochoria korsakowii</em>, <em>Ottelia alismoides</em> and <em>Chara braunii</em>. Preventing disturbances that suppress the growth of herbaceous perennial plants is considered necessary for maintaining the habitats of threatened plant species.展开更多
A bacterial strain,pcnb-21,capable of degrading pentachloronitrobenzene(PCNB) under aerobic and anoxic conditions,was isolated from a long-term PCNB-polluted soil by an enrichment culture technique and identified as L...A bacterial strain,pcnb-21,capable of degrading pentachloronitrobenzene(PCNB) under aerobic and anoxic conditions,was isolated from a long-term PCNB-polluted soil by an enrichment culture technique and identified as Labrys portucalensis based upon its morphological,physiological and biochemical properties,as well as 16S rRNA gene sequence analysis.Effects of different factors,such as temperature and pH,on PCNB biodegradation were studied.Strain pcnb-21 efficiently degraded PCNB at temperatures from 20 to 30 ℃ and initial pH values from 4 to 7,which might be the first time that a Labrys strain was found capable of efficiently degrading PCNB.The degradation of PCNB was affected by oxygen,and the degradation decreased with increasing aeration.Exogenous electron donors such as glucose,lactic acid and succinic acid promoted the biodegradation of PCNB,while electron acceptors such as sodium nitrite,sodium sulfate,sodium nitrate and sodium sulfate inhibited PCNB biodegradation.The degradation of PCNB in sterile and non-sterile soils by a green fluorescent protein(GFP)-labeled strain,pcnb-21-gfp,was also studied.Cells of pcnb-21-gfp efficiently degraded 100 mg kg -1 PCNB in sterile and non-sterile soils and could not be detected after 42 days.Strain pcnb-21 might be useful in bioremediating PCNB-polluted soils and environment.展开更多
The application of electron donor and electron shuttle substances has a vital influence on electron transfer,thus may affect the reductive dechlorination of 1,1,1-trichoro-2,2-bis（p-chlorophenyl）ethane（DDT） in ana...The application of electron donor and electron shuttle substances has a vital influence on electron transfer,thus may affect the reductive dechlorination of 1,1,1-trichoro-2,2-bis（p-chlorophenyl）ethane（DDT） in anaerobic reaction systems.To evaluate the roles of citric acid and anthraquinone-2,6-disulfonate（AQDS） in accelerating the reductive dechlorination of DDT in Hydragric Acrisols that contain abundant iron oxide,a batch anaerobic incubation experiment was conducted in a slurry system with four treatments of（1） control,（2） citric acid,（3） AQDS,and（4） citric acid ＋ AQDS.Results showed that DDT residues decreased by 78.93%-92.11% of the initial quantities after 20 days of incubation,and 1,1-dichloro-2,2-bis（4-chlorophenyl）-ethane（DDD） was the dominant metabolite.The application of citric acid accelerated DDT dechlorination slightly in the first 8 days,while the methanogenesis rate increased quickly,and then the acceleration effect improved after the 8th day while the methanogenesis rate decreased.The amendment by AQDS decreased the Eh value of the reaction system and accelerated microbial reduction of Fe（III） oxides to generate Fe（II）,which was an efficient electron donor,thus enhancing the reductive dechlorination rate of DDT.The addition of citric acid ＋ AQDS was most efficient in stimulating DDT dechlorination,but no significant interaction between citric acid and AQDS on DDT dechlorination was observed.The results will be of great significance for developing an efficient in situ remediation strategy for DDT-contaminated sites.展开更多
文摘Threatened or near threatened hydrophytes, <em>Ottelia alismoides</em>, <em>Monochoria korsakowii</em>, <em>Najas graminea</em>, <em>Najas minor</em> and <em>Chara braunii</em>, appeared in an inundated paddy field after the 2011 Tohoku-oki Tsunami in Japan. Due to the reconstruction of roads and agricultural restoration efforts implemented following the disaster, the top soil of the paddy field was transplanted to another abandoned paddy field in 2014 to avoid extirpation of the aforementioned species. We then conducted vegetation surveys in July and September from 2014 to 2016. <em>Monochoria korsakowii</em> appeared at the transplantation site from 2014 to 2016, forming a large community in 2016. The volume of this species was significantly higher than that in July 2014 and 2015. Although <em>Ottelia alismoides</em> and<em> Chara braunii</em> appeared in 2014, they were not observed in 2015. <em>Najas graminea</em> and<em> Najas minor</em> were not observed during the vegetation survey, and<em> Salvinia natans</em> and<em> Alisma plantago-aquatica</em> newly appeared at the transplantation site. Our findings suggest that transplantation of surface soil and the seed bank therein to an abandoned paddy field is well suited for the conservation of hygrophytes such as <em>Monochoria korsakowii</em>, <em>Ottelia alismoides</em> and <em>Chara braunii</em>. Preventing disturbances that suppress the growth of herbaceous perennial plants is considered necessary for maintaining the habitats of threatened plant species.
基金Supported by the National High Technology Research and Development Program of China (No. 2007AA10Z405)the National Natu-ral Science Foundation of China (No. 31070100)the Key Technology R&D Program of Jiangsu Province,China (No. BE2008669)
文摘A bacterial strain,pcnb-21,capable of degrading pentachloronitrobenzene(PCNB) under aerobic and anoxic conditions,was isolated from a long-term PCNB-polluted soil by an enrichment culture technique and identified as Labrys portucalensis based upon its morphological,physiological and biochemical properties,as well as 16S rRNA gene sequence analysis.Effects of different factors,such as temperature and pH,on PCNB biodegradation were studied.Strain pcnb-21 efficiently degraded PCNB at temperatures from 20 to 30 ℃ and initial pH values from 4 to 7,which might be the first time that a Labrys strain was found capable of efficiently degrading PCNB.The degradation of PCNB was affected by oxygen,and the degradation decreased with increasing aeration.Exogenous electron donors such as glucose,lactic acid and succinic acid promoted the biodegradation of PCNB,while electron acceptors such as sodium nitrite,sodium sulfate,sodium nitrate and sodium sulfate inhibited PCNB biodegradation.The degradation of PCNB in sterile and non-sterile soils by a green fluorescent protein(GFP)-labeled strain,pcnb-21-gfp,was also studied.Cells of pcnb-21-gfp efficiently degraded 100 mg kg -1 PCNB in sterile and non-sterile soils and could not be detected after 42 days.Strain pcnb-21 might be useful in bioremediating PCNB-polluted soils and environment.
基金supported by the National Natural Science Foundation of China (No.41201314)the Open Fund Project of State Key Laboratory of Soil and Sustainable Agriculture (No.0812201227)
文摘The application of electron donor and electron shuttle substances has a vital influence on electron transfer,thus may affect the reductive dechlorination of 1,1,1-trichoro-2,2-bis（p-chlorophenyl）ethane（DDT） in anaerobic reaction systems.To evaluate the roles of citric acid and anthraquinone-2,6-disulfonate（AQDS） in accelerating the reductive dechlorination of DDT in Hydragric Acrisols that contain abundant iron oxide,a batch anaerobic incubation experiment was conducted in a slurry system with four treatments of（1） control,（2） citric acid,（3） AQDS,and（4） citric acid ＋ AQDS.Results showed that DDT residues decreased by 78.93%-92.11% of the initial quantities after 20 days of incubation,and 1,1-dichloro-2,2-bis（4-chlorophenyl）-ethane（DDD） was the dominant metabolite.The application of citric acid accelerated DDT dechlorination slightly in the first 8 days,while the methanogenesis rate increased quickly,and then the acceleration effect improved after the 8th day while the methanogenesis rate decreased.The amendment by AQDS decreased the Eh value of the reaction system and accelerated microbial reduction of Fe（III） oxides to generate Fe（II）,which was an efficient electron donor,thus enhancing the reductive dechlorination rate of DDT.The addition of citric acid ＋ AQDS was most efficient in stimulating DDT dechlorination,but no significant interaction between citric acid and AQDS on DDT dechlorination was observed.The results will be of great significance for developing an efficient in situ remediation strategy for DDT-contaminated sites.
