This study was conducted to investigate the effects of mixed biochar on the nitrification rate in acidic soils. A15 N tracer experiment with(15 NH4)2 SO4 was conducted to determine the nitrification rates of 4 acidic ...This study was conducted to investigate the effects of mixed biochar on the nitrification rate in acidic soils. A15 N tracer experiment with(15 NH4)2 SO4 was conducted to determine the nitrification rates of 4 acidic agricultural soils with p H 4.03-6.02 in Yunnan Province, Southern China. The accumulation of15 N-NO3-and nitrification rates decreased with the addition of biochar at the end of incubation, suggesting that biochar could be a nitrification inhibitor in acidic fertilized soil. Nitrification rates in soil with p H 4.03 were evidently lower than those in soil with p H 4.81-6.02 with or without biochar. Decreased nitrification rates were detected in the acidic soils with biochar. Soil p H controlled nitrification more than biochar in certain strongly acidic soils.展开更多
A red soil, a fluvo-aquic soil and a permeable paddy soil were used in a long-term investigation to study changes in nitrification with treatments: 1) soil incubation, 2) liquid incubation inoculated with soil samples...A red soil, a fluvo-aquic soil and a permeable paddy soil were used in a long-term investigation to study changes in nitrification with treatments: 1) soil incubation, 2) liquid incubation inoculated with soil samples, and 3) liquid incubation inoculated with ammonia-oxidizing bacteria (AOB) from the soils. There were significant differences (P < 0.001) in nitrification rates among the three soils when measured for 28 days by adding (NH4)SO4 at the rate of 154 mg N kg-1 dry soil to fresh soil. However, t…展开更多
The intensive use of nitrogen fertilizers in Algeria caused a pollution of the waters by nitrates. This concentration reached in the region of Collo （Wilaya of Skikda, Algeria） 570 mg/L, which is beyond the WHO stan...The intensive use of nitrogen fertilizers in Algeria caused a pollution of the waters by nitrates. This concentration reached in the region of Collo （Wilaya of Skikda, Algeria） 570 mg/L, which is beyond the WHO standard （50 mg/L）. This has negative consequences on human health （Methemoglobinemia） and on the environment （eutrophication）. In our works, we studied the elimination of this pollution with the use of a mixed culture of microorganisms. We replaced the standard synthetic carbon source and the nutritious medium by date powder. This contains minerals and sugars that can enhance bacterial growth. Our study showed that the effectiveness of denitrification is proportional to bacterial growth. It rises exponentially after a latency period of 8 hours. During the reaction of degradation we noticed a rise in pH in our engine, it moved from 7.00 to 8.38. In studying the influence of initial pH on the denitrification of the microorganisms, we observed that the ion hydrogen concentration modified the growth rate of bacteria and degradation of nitrates. An acid pH, the reduction of nitrates is incomplete; this is accounted for the accumulation of nitrous and nitric oxide that interferes in the reaction of denitrification. The velocity of the nitrate reduction is less important in an acid pH （0.0096 g.L^-l.h^-1） than in a basic pH （0.013 g.L^-1.h^-1）. The denitrification is optimal at temperature 35 ℃ for a ratio C/N = 2.5. In these conditions 95% of the nitrate initial quantity is eliminated after approximately 100 hour treatment.展开更多
The effect of accompanying anions on the adsorbability and extractability of Pb added in soils was studied by using bach equilibria and incubation-extraction mothods.Pb concentration ranged between 0.48-2.41 mM in the...The effect of accompanying anions on the adsorbability and extractability of Pb added in soils was studied by using bach equilibria and incubation-extraction mothods.Pb concentration ranged between 0.48-2.41 mM in the adsorption experiment,and Pb added to soil from 2.14 to 19.31mM Pb/kg with an incubation time of 2-16 weeks in the incubation-extraction test in which 1M NH4OAc(pH 7) was taken as an extraction agent,and the Pb compounds used are PbCl2,Pb(NO3)2 and Pb(OAc)2.The values of pH50 for Pb retention and the parameters,b and k values,of Langmuir equation were used to distinguish the difference of adsorbability and extractability of Pb affected by anions,respectively.Judging from the results of either pH50 value or b value,the influences of Cl^- and NO3^- on the adsorbability and extractability of Pb in soils were similar but quite different from those of OAc^-.The relative loading capacities of soils to Pb calculated according to the extraction rate showed that the values of Pb(OAc)2 were higher than those of PbCl2 and Pb(NO3)2.展开更多
A study about some physicochemical parameters of Egbe reservoir was carried out from September 2005 to December 2006. The parameters include mean temperature, pH, conductivity, alkalinity, TSS, TDS, DO and BOD which h...A study about some physicochemical parameters of Egbe reservoir was carried out from September 2005 to December 2006. The parameters include mean temperature, pH, conductivity, alkalinity, TSS, TDS, DO and BOD which have values of 28.7±0.9 ℃ ; 8.3±0.3; 831±172.5 μS/cm; 165.4±18.3 mg/L; 0.06±0.1 mg/L; 0.4±0.6 mg/L; 7.8±2.4 mg/L and 5.2±1.6mg/L, respectively. Temperature and pH were measured in the field using mercury-in-glass thermometer calibrated in degrees Celsius and pH meter, respectively. TSS and TDS were measured by grayimetric methods, while alkalinity was measured titrimetrically and DO and BOD were measured by Winkler＇s method. For the nutrients, nitrate was measured color±metrically, phosphate by Stannous Chloride method and sulphate by turbidimetric method. Mean concentration of nitrate, phosphate, and sulphate were 15.6±8.6 rag/L; 42.5±19.4 mg/L and 72.3±14.7 mg/L respectively. Nowadays, eutrophication of natural waters is one of the most significant causes of deterioration of water quality, and nitrates and phosphates are probably the key nutrients in controlling the growth of aquatic plants. Though the mean concentration of nitrates and phosphates in the reservoir water were within the acceptable limit, yet their concentrations in some locations of reservoir were high enough to encourage the growth of aquatic macrophytes which would increase productivities. Hence, it is necessary to check their further increase, and periodic monitoring and preventive measures must be adopted to save the reservoir from eutrophication.展开更多
Rapeseed cake （RC）, the residue of rapeseed oil extraction, is effective for improving tea （Camellia sinensis） quality, especially taste and aroma, but it has limited ability to ameliorate strongly acidic soil. In...Rapeseed cake （RC）, the residue of rapeseed oil extraction, is effective for improving tea （Camellia sinensis） quality, especially taste and aroma, but it has limited ability to ameliorate strongly acidic soil. In order to improve the liming potential of RC, alkaline slag （AS）, the by-product of recovery of sodium carbonate, was incorporated. Combined effects of different levels of RC and AS on ameliorating acidic soil from a tea garden were investigated. Laboratory incubations showed that combined use of AS and RC was an effective method to reduce soil exchangeable acidity and A1 saturation and increase base saturation, but not necessarily for soil pH adjustment. The release of alkalinity from the combined amendments and the mineralization of organic nitrogen increased soil pH initially, but then soil pH decreased due to nitrifications. Various degrees of nitrification were correlated with the interaction of different Ca levels, pH and N contents. When RC was applied at low levels, high Ca levels from AS repressed soil nitrification, resulting in smaller pH fluctuations. In contrast, high AS stimulated soil nitrification, when RC was applied at high levels, and resulted in a large pH decrease. Based on the optimum pH for tea production and quality, high ratios of AS to RC were indicated for soil acidity amelioration, and 8.0 g kg-1 and less than 2.5 g kg-1 were indicated for AS and RC, respectively. Further, field studies are needed to investigate the variables of combined amendments.展开更多
基金Supported by National Natural Science Foundation of China(31201688)Yunnan University’s Research Innovation Fund for Graduate Students
文摘This study was conducted to investigate the effects of mixed biochar on the nitrification rate in acidic soils. A15 N tracer experiment with(15 NH4)2 SO4 was conducted to determine the nitrification rates of 4 acidic agricultural soils with p H 4.03-6.02 in Yunnan Province, Southern China. The accumulation of15 N-NO3-and nitrification rates decreased with the addition of biochar at the end of incubation, suggesting that biochar could be a nitrification inhibitor in acidic fertilized soil. Nitrification rates in soil with p H 4.03 were evidently lower than those in soil with p H 4.81-6.02 with or without biochar. Decreased nitrification rates were detected in the acidic soils with biochar. Soil p H controlled nitrification more than biochar in certain strongly acidic soils.
基金1Project supported by the National Natural Science Foundation of China (NSFC) (Nos. 40271098 and 40471074).
文摘A red soil, a fluvo-aquic soil and a permeable paddy soil were used in a long-term investigation to study changes in nitrification with treatments: 1) soil incubation, 2) liquid incubation inoculated with soil samples, and 3) liquid incubation inoculated with ammonia-oxidizing bacteria (AOB) from the soils. There were significant differences (P < 0.001) in nitrification rates among the three soils when measured for 28 days by adding (NH4)SO4 at the rate of 154 mg N kg-1 dry soil to fresh soil. However, t…
文摘The intensive use of nitrogen fertilizers in Algeria caused a pollution of the waters by nitrates. This concentration reached in the region of Collo （Wilaya of Skikda, Algeria） 570 mg/L, which is beyond the WHO standard （50 mg/L）. This has negative consequences on human health （Methemoglobinemia） and on the environment （eutrophication）. In our works, we studied the elimination of this pollution with the use of a mixed culture of microorganisms. We replaced the standard synthetic carbon source and the nutritious medium by date powder. This contains minerals and sugars that can enhance bacterial growth. Our study showed that the effectiveness of denitrification is proportional to bacterial growth. It rises exponentially after a latency period of 8 hours. During the reaction of degradation we noticed a rise in pH in our engine, it moved from 7.00 to 8.38. In studying the influence of initial pH on the denitrification of the microorganisms, we observed that the ion hydrogen concentration modified the growth rate of bacteria and degradation of nitrates. An acid pH, the reduction of nitrates is incomplete; this is accounted for the accumulation of nitrous and nitric oxide that interferes in the reaction of denitrification. The velocity of the nitrate reduction is less important in an acid pH （0.0096 g.L^-l.h^-1） than in a basic pH （0.013 g.L^-1.h^-1）. The denitrification is optimal at temperature 35 ℃ for a ratio C/N = 2.5. In these conditions 95% of the nitrate initial quantity is eliminated after approximately 100 hour treatment.
文摘The effect of accompanying anions on the adsorbability and extractability of Pb added in soils was studied by using bach equilibria and incubation-extraction mothods.Pb concentration ranged between 0.48-2.41 mM in the adsorption experiment,and Pb added to soil from 2.14 to 19.31mM Pb/kg with an incubation time of 2-16 weeks in the incubation-extraction test in which 1M NH4OAc(pH 7) was taken as an extraction agent,and the Pb compounds used are PbCl2,Pb(NO3)2 and Pb(OAc)2.The values of pH50 for Pb retention and the parameters,b and k values,of Langmuir equation were used to distinguish the difference of adsorbability and extractability of Pb affected by anions,respectively.Judging from the results of either pH50 value or b value,the influences of Cl^- and NO3^- on the adsorbability and extractability of Pb in soils were similar but quite different from those of OAc^-.The relative loading capacities of soils to Pb calculated according to the extraction rate showed that the values of Pb(OAc)2 were higher than those of PbCl2 and Pb(NO3)2.
文摘A study about some physicochemical parameters of Egbe reservoir was carried out from September 2005 to December 2006. The parameters include mean temperature, pH, conductivity, alkalinity, TSS, TDS, DO and BOD which have values of 28.7±0.9 ℃ ; 8.3±0.3; 831±172.5 μS/cm; 165.4±18.3 mg/L; 0.06±0.1 mg/L; 0.4±0.6 mg/L; 7.8±2.4 mg/L and 5.2±1.6mg/L, respectively. Temperature and pH were measured in the field using mercury-in-glass thermometer calibrated in degrees Celsius and pH meter, respectively. TSS and TDS were measured by grayimetric methods, while alkalinity was measured titrimetrically and DO and BOD were measured by Winkler＇s method. For the nutrients, nitrate was measured color±metrically, phosphate by Stannous Chloride method and sulphate by turbidimetric method. Mean concentration of nitrate, phosphate, and sulphate were 15.6±8.6 rag/L; 42.5±19.4 mg/L and 72.3±14.7 mg/L respectively. Nowadays, eutrophication of natural waters is one of the most significant causes of deterioration of water quality, and nitrates and phosphates are probably the key nutrients in controlling the growth of aquatic plants. Though the mean concentration of nitrates and phosphates in the reservoir water were within the acceptable limit, yet their concentrations in some locations of reservoir were high enough to encourage the growth of aquatic macrophytes which would increase productivities. Hence, it is necessary to check their further increase, and periodic monitoring and preventive measures must be adopted to save the reservoir from eutrophication.
基金Supported by the National Key Technology R&D Program of China(No.2009BADC6B02)the National Environmental Protection Public Benefit Research Foundation of China(No.2013467036)the National Natural Science Foundation of China(Nos.41030531 and 40701078)
文摘Rapeseed cake （RC）, the residue of rapeseed oil extraction, is effective for improving tea （Camellia sinensis） quality, especially taste and aroma, but it has limited ability to ameliorate strongly acidic soil. In order to improve the liming potential of RC, alkaline slag （AS）, the by-product of recovery of sodium carbonate, was incorporated. Combined effects of different levels of RC and AS on ameliorating acidic soil from a tea garden were investigated. Laboratory incubations showed that combined use of AS and RC was an effective method to reduce soil exchangeable acidity and A1 saturation and increase base saturation, but not necessarily for soil pH adjustment. The release of alkalinity from the combined amendments and the mineralization of organic nitrogen increased soil pH initially, but then soil pH decreased due to nitrifications. Various degrees of nitrification were correlated with the interaction of different Ca levels, pH and N contents. When RC was applied at low levels, high Ca levels from AS repressed soil nitrification, resulting in smaller pH fluctuations. In contrast, high AS stimulated soil nitrification, when RC was applied at high levels, and resulted in a large pH decrease. Based on the optimum pH for tea production and quality, high ratios of AS to RC were indicated for soil acidity amelioration, and 8.0 g kg-1 and less than 2.5 g kg-1 were indicated for AS and RC, respectively. Further, field studies are needed to investigate the variables of combined amendments.
