The percent ammonia nitrogen was determined in Passaic River waste water using Ion-Selective Electrode EPA Method 350.3. The intelligent ammonia sensor integrates ammonia electrode, pH electrode and Ammonia Ion electr...The percent ammonia nitrogen was determined in Passaic River waste water using Ion-Selective Electrode EPA Method 350.3. The intelligent ammonia sensor integrates ammonia electrode, pH electrode and Ammonia Ion electrode together to realize the in situ detection of ammonia. The test results have shown that the sensor is easy operation, low cost and no pollution. The ammonia is determined potentiometrically using an ammonia ion selective electrode and a pH/mV meter, having an expanded millivolt scale. The ammonia selective electrode uses a hydrophobic gas-permeable membrane to separate the sample solution from an electrode internal solution of ammonium chloride. Dissolved ammonia is converted to NH<sub>3</sub> gas by raising the pH to above 11.0 with a strong base. NH<sub>3</sub> gas diffuses the membrane and changes the internal solution pH that is sensed by the electrode. In single laboratory test results have been found 1.001 NH<sub>3</sub>-/L and 0.897 mg NH<sub>3</sub>-N/L, recoveries were 77.3% and 83.1%, respectively.展开更多
[Objective] The treatment effect of inner circulation impinging stream biofilm reactor(ICISBR) on high strength ammonia wastewater was studied.[Method] By means of ICISBR,high strength ammonia wastewater was treated b...[Objective] The treatment effect of inner circulation impinging stream biofilm reactor(ICISBR) on high strength ammonia wastewater was studied.[Method] By means of ICISBR,high strength ammonia wastewater was treated by using corncob as biological carrier,and the effect of C/N and dissolved oxygen(DO) on the removal effect of chemical oxygen demand(COD) and ammonia nitrogen(NH+4-N) were discussed in our paper.[Result] When NH+4-N and DO in effluent water were 200 and 2 mg/L,respectively,the removal effect of COD was not affected obviously whether C/N was 1.0 or 1.5,reaching above 92%;when C/N was 1.5,the average removal rate of COD and NH+4-N were the highest,namely 92.7% and 41.2%,respectively;when C/N was 2.0,the average removal rate of COD and NH+4-N decreased obviously to 20% and 10%;when C/N and NH+4-N were 1.5 and 200 mg/L,DO had little effects on the removal of COD and great effects on the removal of NH+4-N,namely the removal rate of NH+4-N decreased to 17.1% from 46.4% with the reduction of DO concentration from 4 to 1 mg/L.[Conclusion] Our study could provide theoretical basis for the treatment of high strength ammonia wastewater.展开更多
Effects of reduced salinity on the oxygen consumption rate (OCR) and the ammonia N excretion rate (AER) of scallop Chlamys farreri (3.2 5.9 cm in shell height, 0.147 1.635 g in soft tissue dry weight ) were studied in...Effects of reduced salinity on the oxygen consumption rate (OCR) and the ammonia N excretion rate (AER) of scallop Chlamys farreri (3.2 5.9 cm in shell height, 0.147 1.635 g in soft tissue dry weight ) were studied in laboratory from March 21,1997 to April 16, 1997. Under the controlled conditions of reduced salinity from 31.5 to 15.0 and ambient temperature 17℃ and 23℃, the concentrations of dissolved oxygen and ammonia N were determined by the Winkle method and the hypobromite method, respectively. Results showed that with controlled reduced salinity, the mean values of the OCR were 2.17 mg/(g.h) at 17℃, and 2.86 mg/(g.h) at 23℃and that the mean values of the AER were 178.0 μg/(g.h) at 17℃ and 147.0 μg/(g.h) at 23℃. The OCR and the AER decreased with reducing salinity from 31.5 to 15.0 both at 17℃ and 23℃. The effects of reduced salinity on the OCR and the AER of scallop C. farreri could be represented by the allometric equation and the exponential equation, respectively.展开更多
A pilot scale zeolite medium biological aerated filter(ZBAF) was designed and used to treat municipal wastewater. It showed that ZBAF could simultaneously remove chemical oxygen demand(COD), ammonia-N and turbidity to...A pilot scale zeolite medium biological aerated filter(ZBAF) was designed and used to treat municipal wastewater. It showed that ZBAF could simultaneously remove chemical oxygen demand(COD), ammonia-N and turbidity to satisfied degree at a hydraulic retention time(HRT) of 0.95 h. Their average removal efficiencies were 73.9%, 88.4% and 96.2% with the corresponding average effluent concentrations of 43.4 mg/L, 3.5 mg/L and 3.7 NTU, respectively. These effluent items met with the water quality standard of the treated water reused for cooling water. The COD removal volumetric loading rate increased proportionally with its applied volumetric loading rate with its maximum of 7.1 kg/(m 3·d). Ammonia-N removal loading rate also increased proportionally with its applied loading rate at HRT of longer than 0.95 h and the feasible maximum removal loading rate was 0.9 kg/(m 3·d). The COD loading rate did not affect the ammonia-N removal efficiency significantly when it was lower than 5.5 kg/(m 3·d). ZBAF has good application prospect for its low cost and high removal efficiency in the future.展开更多
The juveniles of hybrid tilapia （ Oreochromis niloticus x Oreochromis areus） were exposed to ananonia-nitrogen （N） （0, 2.5, 5, 10 and 20 mg/L） for 0, 12, 24, 48 and 72 h to evaluate the effect of ammonia-N stres...The juveniles of hybrid tilapia （ Oreochromis niloticus x Oreochromis areus） were exposed to ananonia-nitrogen （N） （0, 2.5, 5, 10 and 20 mg/L） for 0, 12, 24, 48 and 72 h to evaluate the effect of ammonia-N stress on their non-specific immunity. Results show that the activity of serum lysozyme decreased signifi- candy with extension of stress time （P 〈 0.05）. The total antioxidant capacity （T-AOC） and activity of antioxidase in liver were significantly affected. The activi- ty of T-AOC and total superoxide dismutase （T-SOD） of fish exposed to ammonia-N were initially decreasing then increasing （ P 〈 0.05 ）. Activities of catalase （CAT） and glutathione peroxidase （GSH-Px） were correlated with concentrations of ammonia-N. Fish exposed to lower concentrations （2.5 mg/L or 5 mg/L） showed decreased CAT activity within 24 h （P 〈 0.05 ）, while those exposed to higher concentrations （10 mg/L or 20 mg/L） initially showed increased then decreased activity of CAT. Except for the highest concentration groups, fish exposed to ammonia-N showed inductive activity of GSH-Px （ P 〈 0.05 ）. Under the ex- perimental conditions, non-specific immunity of tilapia was affected by ammonia-N stress, and the impact was increased with increased concentration and extension of time.展开更多
Field experiments were conducted in 2006 to investigate the impacts of modified rice cultivation systems on: grain yield, N uptake, ammonia volatilization from rice soil and N use efficiency (ANUE, agronomic N use eff...Field experiments were conducted in 2006 to investigate the impacts of modified rice cultivation systems on: grain yield, N uptake, ammonia volatilization from rice soil and N use efficiency (ANUE, agronomic N use efficiency;and PFP, partial factor productivity of applied N). The trials compared rice production using modified methods of irrigation, planting, weeding and nutrient management (the system of rice intensification, SRI) with traditional flooding (TF). The effects of different N application rates (0, 80, 160, 240 kg ha-1) and of N rates interacting with cultivation methods were also evaluated. Grain yields ranged from 5.6 to 6.9 t ha-1 with SRI, and from 4.0 to 6.1 t ha-1 under TF management. On average, grain yields under SRI were 24% higher than that with TF. Ammonia volatilization was increased significantly under SRI compared with TF and the average total amount of ammonia volatilization loss during the rice growth stage under SRI was 22% higher than TF. With increases in application rate, N uptake by rice increased, and the ratio of N in the seed to total N in the plant decreased. Furthermore, results showed that higher ANUE was achieved at a relatively low N fertilizer rate (80 kg ha-1 N) with SRI. Results of these studies suggest that SRI increased rice yield and N uptake and improved ammonia volatilization loss from rice soil compared with TF. Moreover, there were significant interactions between N application rates and cultivation methods. We conclude that it was the most important to adjust the amount of N application under SRI, such as reducing the amount of N application. Research on effects of N fertilizer on rice yield and environmental pollution under SRI may be worth further studying.展开更多
Polychaetes provide an excellent food resource for fi sh and represent the dominant zoobenthos in marine ecosystems. Diel variation in the rates of metabolism and ammonia-N excretion of Marphysa sanguinea were studied...Polychaetes provide an excellent food resource for fi sh and represent the dominant zoobenthos in marine ecosystems. Diel variation in the rates of metabolism and ammonia-N excretion of Marphysa sanguinea were studied. The worms were grouped according to their wet body weight into small（S; 1.24±0.06 g）, medium（M; 4.00±0.30 g）, and large（L; 8.54±1.08 g） categories. Their weight-specifi c metabolic rates, based on aerobic respiration（ R）, were measured at 16℃（±0.2℃） and classed as either routine（ RR） or standard（ RS） rates. Both respiration types decreased with increasing body weight. Respiration was described by R = a W^b, where b was-0.400 9 and-0.532 0 for RR and RS, respectively. Diurnal changes in RS for each group was relatively flat, with a slightly increasing trend with time, but was relatively stable as a whole. RR of the diurnal variation of worms was higher than RS, but both had similar overall trends. The peak values of specifi c dynamic action（SDA）（ RSDA） in the S, M, and L groups were 2.704, 1.149, and 0.682 mg/（g·h）, respectively. The durations of SDA were 13, 6, and 6 h, respectively and the energy expenditures of SDA were 377.98, 117.34, and 74.94 J/g, respectively. These data indicate that the metabolic rates were higher in smaller individuals, which is advantageous for their rapid growth.展开更多
Nitrogen（N） loss from fertilization in agricultural fields has an unavoidable negative impact on the environment and a better understanding of the major pathways can assist in developing the best management practice...Nitrogen（N） loss from fertilization in agricultural fields has an unavoidable negative impact on the environment and a better understanding of the major pathways can assist in developing the best management practices. The aim of this study was to evaluate the fate of N fertilizers applied to acidic red soil（Ferralic Cambisol） after 19 years of mineral（synthetic） and manure fertilizer treatments under a cropping system with wheat-maize rotations. Five field treatments were examined： control（CK）, chemical nitrogen and potash fertilizer（NK）, chemical nitrogen and phosphorus fertilizer（NP）, chemical nitrogen, phosphorus and potash fertilizer（NPK） and the NPK with manure（NPKM, 70% N from manure）. Based on the soil total N storage change in 0–100 cm depth, ammonia（NH_3） volatilization, nitrous oxide（N_2O） emission, N plant uptake, and the potential N leaching loss were estimated using a mass balance approach. In contrast to the NPKM, all mineral fertilizer treatments（NK, NP and NPK） showed increased nitrate（NO_3~–） concentration with increasing soil depth, indicating higher leaching potential. However, total NH_3 volatilization loss was much higher in the NPKM（19.7%） than other mineral fertilizer treatments（≤4.2%）. The N_2O emissions were generally low（0.2–0.9%, the highest from the NPKM）. Total gaseous loss accounted for 1.7, 3.3, 5.1, and 21.9% for NK, NP, NPK, and NPKM treatments, respectively. Estimated N leaching loss from the NPKM was only about 5% of the losses from mineral fertilizer treatments. All data demonstrated that manure incorporation improved soil productivity, increased yield, and reduced potential leaching, but with significantly higher NH_3 volatilization, which could be reduced by improving the application method. This study confirms that manure incorporationis an essential strategy in N fertilization management in upland red soil cropping system.展开更多
In natural water, the content of ammonia nitrogen is always kept at a low level. However, the ammonia nitrogen content in water will be elevated or even excessive when the density of aquaculture is too large or exogen...In natural water, the content of ammonia nitrogen is always kept at a low level. However, the ammonia nitrogen content in water will be elevated or even excessive when the density of aquaculture is too large or exogenous ammonia are discharged into the water, causing a series of ad-verse effects on fish survival. Within a certain range, fishes reduce ammonia production in vivo by converting ammonia into glutamine and urea, and increase NH3 volatilization and NH4+emissions to ease ammonia toxicity, but the ability to alleviate ammonia poisoning vary with fish species and size. The ammonia nitrogen sources, existence form, factors affecting toxicity, toxic mechanism and detoxification strategy of fish are reviewed, in or-der to provide reference for improving the ability of fish to alleviate ammonia nitrogen toxicity and healthy farming.展开更多
of temperature on oxygen consumption rate (OCR) and ammonia-N excretion rate of scallop Chlamys farreri (1.7-6.2 cm in shell height) were studied in laboratory from Dec. 30 1996 to Jan. 28, 1997 . Under the controlled...of temperature on oxygen consumption rate (OCR) and ammonia-N excretion rate of scallop Chlamys farreri (1.7-6.2 cm in shell height) were studied in laboratory from Dec. 30 1996 to Jan. 28, 1997 . Under the controlled conditions of ambient water temperature 10-31℃ and salinity 32, the concentrations of dissolved oxygen and ammonia-N were determined by the Winkle method and the hypobromite method , respectively . Results showed that the OCR ranged from 1.20 mg/g (DW). h to 5.76mg/g (DW). h. The OCR increased with temperature from 10℃ to 23℃, but at 28℃ the OCR of mature individuals decreased, and that of different size scallops reduced at 31℃. The ammonia-N excretion rate ranged from 113.13 μg NH4-N/g (DW). h to 486.63 μg NH4 -N/g (DW). h,and increased with temperature from 10℃ to 31℃.展开更多
Fluid catalytic cracking (FCC) salty wastewaters, containing quaternary ammonium compounds (QACs), are very difficult to treat by biochemical process. Anoxic/oxic (A/O) biochemical system, based on nitrification and d...Fluid catalytic cracking (FCC) salty wastewaters, containing quaternary ammonium compounds (QACs), are very difficult to treat by biochemical process. Anoxic/oxic (A/O) biochemical system, based on nitrification and denitrification reactions, was used to assess their possible biodegradation. Because of the negative effects of high salt concentration (3%), heavy metals and toxic organic matter on microorganisms’ activities, some techniques consisting of dilution, coagulation and flocculation, and ozonation pretreatments, were gradually tested to evaluate chemical oxygen demand (COD), ammonia-nitrogen (ammonia-N) and total nitrogen (TN) removal rates. In this process of FCC wastewater, starting with university-domesticated sludge, the ammonia-N and TN removal rates were worst. However, when using domesticated SBR’s sludge and operating with five-fold daily diluted influent (thus reducing salt concentration), the ammonia-N removal reached about 57% while the TN removal rate was less than 37% meaning an amelioration of the nitrification process. However, by reducing the dilution factors, these results were inflected after some days of operation, with ammonia-N removal decreasing and TN barely removed meaning a poor nitrification. Even by reducing heavy metals concentration with coagulation/flocculation process, the results never changed. Thereafter, by using ozonation pre-treatment to degrade the detected organic matter of di-tert-butylphenol and certain isoparaffins, COD, ammonia-N and TN removal rates reached 92%, 62% and 61%, respectively. These results showed that the activities of the microorganisms were increased, thus indicating a net denitrification and nitrification reactions improvement.展开更多
为了解g型溶菌酶基因序列特征及其在团头鲂(Megahbrama amblycephala)氨氮胁迫过程中的作用,应用末端快速扩增(rapid amplication of c DNA ends,RACE)技术克隆了团头鲂的g型溶菌酶基因c DNA序列,得到全长719 bp的c DNA序列,包括71 bp的...为了解g型溶菌酶基因序列特征及其在团头鲂(Megahbrama amblycephala)氨氮胁迫过程中的作用,应用末端快速扩增(rapid amplication of c DNA ends,RACE)技术克隆了团头鲂的g型溶菌酶基因c DNA序列,得到全长719 bp的c DNA序列,包括71 bp的5'末端非翻译区(untranslated regions,UTR)、90 bp的3'UTR和558 bp的开放阅读框(open reading frame,ORF);氨基酸相似度比对显示,不同鱼类g型溶菌酶的氨基酸序列之间具有较高的保守性,系统进化树分析表明,该基因与草鱼(Ctenopharyngodon idella)g型溶菌酶亲缘关系较近。荧光定量PCR结果显示g型溶菌酶基因在团头鲂各组织中均有表达,肠道中表达量最高,同时在胁迫和恢复过程中该基因在肝和脑中的表达规律相似,均在胁迫时表达量上调,恢复后表达量相对下降,而g型溶菌酶在鳃中的表达有所不同,可推测g型溶菌酶基因参与了氨氮应激分子过程。展开更多
文摘The percent ammonia nitrogen was determined in Passaic River waste water using Ion-Selective Electrode EPA Method 350.3. The intelligent ammonia sensor integrates ammonia electrode, pH electrode and Ammonia Ion electrode together to realize the in situ detection of ammonia. The test results have shown that the sensor is easy operation, low cost and no pollution. The ammonia is determined potentiometrically using an ammonia ion selective electrode and a pH/mV meter, having an expanded millivolt scale. The ammonia selective electrode uses a hydrophobic gas-permeable membrane to separate the sample solution from an electrode internal solution of ammonium chloride. Dissolved ammonia is converted to NH<sub>3</sub> gas by raising the pH to above 11.0 with a strong base. NH<sub>3</sub> gas diffuses the membrane and changes the internal solution pH that is sensed by the electrode. In single laboratory test results have been found 1.001 NH<sub>3</sub>-/L and 0.897 mg NH<sub>3</sub>-N/L, recoveries were 77.3% and 83.1%, respectively.
基金Supported by Key Technology R & D Program of Jiangxi Province (2010BSA19500)Science and Technology Project of Jiujiang University(09kj12)~~
文摘[Objective] The treatment effect of inner circulation impinging stream biofilm reactor(ICISBR) on high strength ammonia wastewater was studied.[Method] By means of ICISBR,high strength ammonia wastewater was treated by using corncob as biological carrier,and the effect of C/N and dissolved oxygen(DO) on the removal effect of chemical oxygen demand(COD) and ammonia nitrogen(NH+4-N) were discussed in our paper.[Result] When NH+4-N and DO in effluent water were 200 and 2 mg/L,respectively,the removal effect of COD was not affected obviously whether C/N was 1.0 or 1.5,reaching above 92%;when C/N was 1.5,the average removal rate of COD and NH+4-N were the highest,namely 92.7% and 41.2%,respectively;when C/N was 2.0,the average removal rate of COD and NH+4-N decreased obviously to 20% and 10%;when C/N and NH+4-N were 1.5 and 200 mg/L,DO had little effects on the removal of COD and great effects on the removal of NH+4-N,namely the removal rate of NH+4-N decreased to 17.1% from 46.4% with the reduction of DO concentration from 4 to 1 mg/L.[Conclusion] Our study could provide theoretical basis for the treatment of high strength ammonia wastewater.
文摘Effects of reduced salinity on the oxygen consumption rate (OCR) and the ammonia N excretion rate (AER) of scallop Chlamys farreri (3.2 5.9 cm in shell height, 0.147 1.635 g in soft tissue dry weight ) were studied in laboratory from March 21,1997 to April 16, 1997. Under the controlled conditions of reduced salinity from 31.5 to 15.0 and ambient temperature 17℃ and 23℃, the concentrations of dissolved oxygen and ammonia N were determined by the Winkle method and the hypobromite method, respectively. Results showed that with controlled reduced salinity, the mean values of the OCR were 2.17 mg/(g.h) at 17℃, and 2.86 mg/(g.h) at 23℃and that the mean values of the AER were 178.0 μg/(g.h) at 17℃ and 147.0 μg/(g.h) at 23℃. The OCR and the AER decreased with reducing salinity from 31.5 to 15.0 both at 17℃ and 23℃. The effects of reduced salinity on the OCR and the AER of scallop C. farreri could be represented by the allometric equation and the exponential equation, respectively.
文摘A pilot scale zeolite medium biological aerated filter(ZBAF) was designed and used to treat municipal wastewater. It showed that ZBAF could simultaneously remove chemical oxygen demand(COD), ammonia-N and turbidity to satisfied degree at a hydraulic retention time(HRT) of 0.95 h. Their average removal efficiencies were 73.9%, 88.4% and 96.2% with the corresponding average effluent concentrations of 43.4 mg/L, 3.5 mg/L and 3.7 NTU, respectively. These effluent items met with the water quality standard of the treated water reused for cooling water. The COD removal volumetric loading rate increased proportionally with its applied volumetric loading rate with its maximum of 7.1 kg/(m 3·d). Ammonia-N removal loading rate also increased proportionally with its applied loading rate at HRT of longer than 0.95 h and the feasible maximum removal loading rate was 0.9 kg/(m 3·d). The COD loading rate did not affect the ammonia-N removal efficiency significantly when it was lower than 5.5 kg/(m 3·d). ZBAF has good application prospect for its low cost and high removal efficiency in the future.
基金Supported by Guangdong Natural Science Foundation(S2013010013693,S2011010003451)Science and Technology Project of Guangdong Province(2013B020307016)Excellent Young Teachers Program of Guangdong(Yq2013152)
文摘The juveniles of hybrid tilapia （ Oreochromis niloticus x Oreochromis areus） were exposed to ananonia-nitrogen （N） （0, 2.5, 5, 10 and 20 mg/L） for 0, 12, 24, 48 and 72 h to evaluate the effect of ammonia-N stress on their non-specific immunity. Results show that the activity of serum lysozyme decreased signifi- candy with extension of stress time （P 〈 0.05）. The total antioxidant capacity （T-AOC） and activity of antioxidase in liver were significantly affected. The activi- ty of T-AOC and total superoxide dismutase （T-SOD） of fish exposed to ammonia-N were initially decreasing then increasing （ P 〈 0.05 ）. Activities of catalase （CAT） and glutathione peroxidase （GSH-Px） were correlated with concentrations of ammonia-N. Fish exposed to lower concentrations （2.5 mg/L or 5 mg/L） showed decreased CAT activity within 24 h （P 〈 0.05 ）, while those exposed to higher concentrations （10 mg/L or 20 mg/L） initially showed increased then decreased activity of CAT. Except for the highest concentration groups, fish exposed to ammonia-N showed inductive activity of GSH-Px （ P 〈 0.05 ）. Under the ex- perimental conditions, non-specific immunity of tilapia was affected by ammonia-N stress, and the impact was increased with increased concentration and extension of time.
文摘Field experiments were conducted in 2006 to investigate the impacts of modified rice cultivation systems on: grain yield, N uptake, ammonia volatilization from rice soil and N use efficiency (ANUE, agronomic N use efficiency;and PFP, partial factor productivity of applied N). The trials compared rice production using modified methods of irrigation, planting, weeding and nutrient management (the system of rice intensification, SRI) with traditional flooding (TF). The effects of different N application rates (0, 80, 160, 240 kg ha-1) and of N rates interacting with cultivation methods were also evaluated. Grain yields ranged from 5.6 to 6.9 t ha-1 with SRI, and from 4.0 to 6.1 t ha-1 under TF management. On average, grain yields under SRI were 24% higher than that with TF. Ammonia volatilization was increased significantly under SRI compared with TF and the average total amount of ammonia volatilization loss during the rice growth stage under SRI was 22% higher than TF. With increases in application rate, N uptake by rice increased, and the ratio of N in the seed to total N in the plant decreased. Furthermore, results showed that higher ANUE was achieved at a relatively low N fertilizer rate (80 kg ha-1 N) with SRI. Results of these studies suggest that SRI increased rice yield and N uptake and improved ammonia volatilization loss from rice soil compared with TF. Moreover, there were significant interactions between N application rates and cultivation methods. We conclude that it was the most important to adjust the amount of N application under SRI, such as reducing the amount of N application. Research on effects of N fertilizer on rice yield and environmental pollution under SRI may be worth further studying.
基金Supported by the National Natural Science Foundation of China(No.30901107)the National Marine Public Welfare Research Project(Nos.201305002,201305043)the Project of Marine Ecological Restoration Technology Research to the Penglai 19-3 Oil Spill Accident(No.19-3YJ09)
文摘Polychaetes provide an excellent food resource for fi sh and represent the dominant zoobenthos in marine ecosystems. Diel variation in the rates of metabolism and ammonia-N excretion of Marphysa sanguinea were studied. The worms were grouped according to their wet body weight into small（S; 1.24±0.06 g）, medium（M; 4.00±0.30 g）, and large（L; 8.54±1.08 g） categories. Their weight-specifi c metabolic rates, based on aerobic respiration（ R）, were measured at 16℃（±0.2℃） and classed as either routine（ RR） or standard（ RS） rates. Both respiration types decreased with increasing body weight. Respiration was described by R = a W^b, where b was-0.400 9 and-0.532 0 for RR and RS, respectively. Diurnal changes in RS for each group was relatively flat, with a slightly increasing trend with time, but was relatively stable as a whole. RR of the diurnal variation of worms was higher than RS, but both had similar overall trends. The peak values of specifi c dynamic action（SDA）（ RSDA） in the S, M, and L groups were 2.704, 1.149, and 0.682 mg/（g·h）, respectively. The durations of SDA were 13, 6, and 6 h, respectively and the energy expenditures of SDA were 377.98, 117.34, and 74.94 J/g, respectively. These data indicate that the metabolic rates were higher in smaller individuals, which is advantageous for their rapid growth.
基金supported by the National Key Research and Development Program of China(2016YFD0200301)the open fund of Key Laboratory of Non-point Source Pollution Control,Ministry of Agriculture,China(20130104)the Key Technologies R&D Program of China during the 12th Five-year Plan period(2012BAD14B04)
文摘Nitrogen（N） loss from fertilization in agricultural fields has an unavoidable negative impact on the environment and a better understanding of the major pathways can assist in developing the best management practices. The aim of this study was to evaluate the fate of N fertilizers applied to acidic red soil（Ferralic Cambisol） after 19 years of mineral（synthetic） and manure fertilizer treatments under a cropping system with wheat-maize rotations. Five field treatments were examined： control（CK）, chemical nitrogen and potash fertilizer（NK）, chemical nitrogen and phosphorus fertilizer（NP）, chemical nitrogen, phosphorus and potash fertilizer（NPK） and the NPK with manure（NPKM, 70% N from manure）. Based on the soil total N storage change in 0–100 cm depth, ammonia（NH_3） volatilization, nitrous oxide（N_2O） emission, N plant uptake, and the potential N leaching loss were estimated using a mass balance approach. In contrast to the NPKM, all mineral fertilizer treatments（NK, NP and NPK） showed increased nitrate（NO_3~–） concentration with increasing soil depth, indicating higher leaching potential. However, total NH_3 volatilization loss was much higher in the NPKM（19.7%） than other mineral fertilizer treatments（≤4.2%）. The N_2O emissions were generally low（0.2–0.9%, the highest from the NPKM）. Total gaseous loss accounted for 1.7, 3.3, 5.1, and 21.9% for NK, NP, NPK, and NPKM treatments, respectively. Estimated N leaching loss from the NPKM was only about 5% of the losses from mineral fertilizer treatments. All data demonstrated that manure incorporation improved soil productivity, increased yield, and reduced potential leaching, but with significantly higher NH_3 volatilization, which could be reduced by improving the application method. This study confirms that manure incorporationis an essential strategy in N fertilization management in upland red soil cropping system.
基金Supported by Research Learning and Innovative Experimental Projects of College Students in Hunan Province(2018138090013)
文摘In natural water, the content of ammonia nitrogen is always kept at a low level. However, the ammonia nitrogen content in water will be elevated or even excessive when the density of aquaculture is too large or exogenous ammonia are discharged into the water, causing a series of ad-verse effects on fish survival. Within a certain range, fishes reduce ammonia production in vivo by converting ammonia into glutamine and urea, and increase NH3 volatilization and NH4+emissions to ease ammonia toxicity, but the ability to alleviate ammonia poisoning vary with fish species and size. The ammonia nitrogen sources, existence form, factors affecting toxicity, toxic mechanism and detoxification strategy of fish are reviewed, in or-der to provide reference for improving the ability of fish to alleviate ammonia nitrogen toxicity and healthy farming.
文摘of temperature on oxygen consumption rate (OCR) and ammonia-N excretion rate of scallop Chlamys farreri (1.7-6.2 cm in shell height) were studied in laboratory from Dec. 30 1996 to Jan. 28, 1997 . Under the controlled conditions of ambient water temperature 10-31℃ and salinity 32, the concentrations of dissolved oxygen and ammonia-N were determined by the Winkle method and the hypobromite method , respectively . Results showed that the OCR ranged from 1.20 mg/g (DW). h to 5.76mg/g (DW). h. The OCR increased with temperature from 10℃ to 23℃, but at 28℃ the OCR of mature individuals decreased, and that of different size scallops reduced at 31℃. The ammonia-N excretion rate ranged from 113.13 μg NH4-N/g (DW). h to 486.63 μg NH4 -N/g (DW). h,and increased with temperature from 10℃ to 31℃.
文摘Fluid catalytic cracking (FCC) salty wastewaters, containing quaternary ammonium compounds (QACs), are very difficult to treat by biochemical process. Anoxic/oxic (A/O) biochemical system, based on nitrification and denitrification reactions, was used to assess their possible biodegradation. Because of the negative effects of high salt concentration (3%), heavy metals and toxic organic matter on microorganisms’ activities, some techniques consisting of dilution, coagulation and flocculation, and ozonation pretreatments, were gradually tested to evaluate chemical oxygen demand (COD), ammonia-nitrogen (ammonia-N) and total nitrogen (TN) removal rates. In this process of FCC wastewater, starting with university-domesticated sludge, the ammonia-N and TN removal rates were worst. However, when using domesticated SBR’s sludge and operating with five-fold daily diluted influent (thus reducing salt concentration), the ammonia-N removal reached about 57% while the TN removal rate was less than 37% meaning an amelioration of the nitrification process. However, by reducing the dilution factors, these results were inflected after some days of operation, with ammonia-N removal decreasing and TN barely removed meaning a poor nitrification. Even by reducing heavy metals concentration with coagulation/flocculation process, the results never changed. Thereafter, by using ozonation pre-treatment to degrade the detected organic matter of di-tert-butylphenol and certain isoparaffins, COD, ammonia-N and TN removal rates reached 92%, 62% and 61%, respectively. These results showed that the activities of the microorganisms were increased, thus indicating a net denitrification and nitrification reactions improvement.
