厌氧条件下土壤反硝化气体(N_2、N_2O、NO)和CO_2排放——氦环境培养—气体同步直接测定法的应用初探
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摘要
反硝化过程是维系闭合氮循环所必需的氮素形态转化环节。土壤反硝化过程速率及产物比的直接测定是研究氮循环过程机理的基础,但却是一个难题。为解决此难题,德国卡尔斯鲁厄技术研究所与中国科学院大气物理研究所最近合作新建了一套通过氦环境培养—气体同步直接测定土壤反硝化气体——氮气(N2)、氧化亚氮(N2O)、一氧化氮(NO)和二氧化碳(CO2)排放的系统和与之配套的三阶段培养方法。为检验该新建系统和配套方法测定土壤反硝化过程的准确性和可靠性,以华北地区广泛分布的盐碱地农田土壤(采自山西运城)为研究对象开展实验室培养试验,在初始可溶性有机碳(DOC)供应比较充足约300mgCkg-1干土(d.s.)的条件下,测试了不同初始土壤硝态氮含量水平(10、100mgNkg-1d.s.左右,分别表示为10N和100N)的反硝化气体和CO2排放过程。结果显示:100N的反硝化速率(定义为N2、N2O和NO排放速率之和)显著高于10N处理(统计检验显著水平p<0.01);两个处理的反硝化产物均以N2为主(质量比分别占77%和75%),产物的NO/N2O摩尔比分别为1.2和1.5,N2O/N2摩尔比均为0.19;土壤反硝化气体动态排放速率及相关指标的测定结果表明,培养土壤中消失的硝态氮被回收81%～87%,培养前后的氮平衡率达92%～95%。因此,该新建方法测定土壤反硝化速率和产物比的结果具有很好的可靠性,为定量研究土壤反硝化过程提供了有效的直接测定手段。研究中检测到的土壤反硝化产物NO/N2O摩尔比大于1,不同于以往用液体培养基纯培养反硝化细菌得出的NO/N2O摩尔比远小于1的结论。这意味着,不能用NO/N2O摩尔比小于1与否来推断土壤排放的N2O和NO是主要来源于反硝化作用还是硝化作用。
Denitrification is the key process of nitrogen transformation to close the global nitrogen cycle. Quantification of microbial denitrification rate and its ratios of products is the key step for obtaining insights into nitrogen cycling processes, though it is very difficult. To enable precise quantification of the rates of the entire process, as well as individual products, a system of gas-flow-soil-core technique with helium-environment incubation was recently established and a three-period incubation method was set up by the Karlsruhe Institute of Technology and the Institute of Atmospheric Physics, Chinese Academy of Sciences. Using this system, dynamic emission rates of dinitrogen (N2), nitrous oxide (N2O), nitric oxide (NO) and carbon dioxide (CO2), which are the gaseous products of microbial denitrification, can be simultaneously and directly measured. In this study, we conducted the first soil incubation experiment to test the reliability of the measurements by this system in association with the newly proposed incubation method. Our experiment included two levels of initial soil nitrate (NO3-) content, which were around 10 and 100 mgN kg1d.s. (dry soil), respectively (hereinafter referred to as 10N and 100N). For either nitrate level, sufficient dissolved organic carbon (DOC) was initially supplied (glucose was added to establish an initial DOC content of around 300 mgC kg1d.s.). The incubated fresh soil was a silty clay loam of the northern China. It was sampled from a typical cropland rotationally cultivated with a double cropping system of summer maize and winter wheat and a single cropping system of cotton. Our results show that the microbial denitrification rate was significantly higher for the 100N than 10N treatments (p<0.01), and N2 was the main product in both treatments (with mass fractions of 77% and 75%, respectively). The molar ratios were 1.2 (10N) to 1.5 (100N) for NO/N 2O and were 0.19 (both treatments) for N2O/N2 . The measurements of individual denitrification gases recovered 81%-87% of disappeared nitrate during incubation. The direct dynamic detection of individual denitrification gases and the measurements of DOC, ammonium, nitrate, microbial biomass carbon, and microbial biomass nitrogen at the beginning and end of incubation gave mass balance rates of 92%-95% for nitrogen. These results suggest that the tested system, in association with the proposed incubation method, could precisely determine the dynamical rate of microbial denitrification. The molar ratios of NO/N2O given by our data were greater than 1. This differs from previous knowledge of much lower ratios yielded by denitrifiers. This difference implicates that the NO/N2O ratio of 1 may not be used as the threshold to indicate nitrification or denitrification processes.
Denitrification is the key process of nitrogen transformation to close the global nitrogen cycle. Quantification of microbial denitrification rate and its ratios of products is the key step for obtaining insights into nitrogen cycling processes, though it is very difficult. To enable precise quantification of the rates of the entire process, as well as individual products, a system of gas-flow-soil-core technique with helium-environment incubation was recently established and a three-period incubation method was set up by the Karlsruhe Institute of Technology and the Institute of Atmospheric Physics, Chinese Academy of Sciences. Using this system, dynamic emission rates of dinitrogen (N2), nitrous oxide (N2O), nitric oxide (NO) and carbon dioxide (CO2), which are the gaseous products of microbial denitrification, can be simultaneously and directly measured. In this study, we conducted the first soil incubation experiment to test the reliability of the measurements by this system in association with the newly proposed incubation method. Our experiment included two levels of initial soil nitrate (NO3-) content, which were around 10 and 100 mgN kg1d.s. (dry soil), respectively (hereinafter referred to as 10N and 100N). For either nitrate level, sufficient dissolved organic carbon (DOC) was initially supplied (glucose was added to establish an initial DOC content of around 300 mgC kg1d.s.). The incubated fresh soil was a silty clay loam of the northern China. It was sampled from a typical cropland rotationally cultivated with a double cropping system of summer maize and winter wheat and a single cropping system of cotton. Our results show that the microbial denitrification rate was significantly higher for the 100N than 10N treatments (p<0.01), and N2 was the main product in both treatments (with mass fractions of 77% and 75%, respectively). The molar ratios were 1.2 (10N) to 1.5 (100N) for NO/N 2O and were 0.19 (both treatments) for N2O/N2 . The measurements of individual denitrification gases recovered 81%-87% of disappeared nitrate during incubation. The direct dynamic detection of individual denitrification gases and the measurements of DOC, ammonium, nitrate, microbial biomass carbon, and microbial biomass nitrogen at the beginning and end of incubation gave mass balance rates of 92%-95% for nitrogen. These results suggest that the tested system, in association with the proposed incubation method, could precisely determine the dynamical rate of microbial denitrification. The molar ratios of NO/N2O given by our data were greater than 1. This differs from previous knowledge of much lower ratios yielded by denitrifiers. This difference implicates that the NO/N2O ratio of 1 may not be used as the threshold to indicate nitrification or denitrification processes.
引文
Anderson I C,Levine J S.1986.Relative rates of nitric oxide and nitrousoxide production by nitrifiers,denitrifiers,and nitrate respirers[J].Applied and Environmental Microbiology,51(5):938-945.
鲍士旦.2000.土壤农化分析[M].北京:中国农业出版社,49-56.BaoShidan.2000.Soil Agricultural Chemistry Analysis(in Chinese)[M].Beijing:China Agriculture Press,49-56.
Bollmann A,Conrad R.1997.Acetylene blockage technique leads tounderestimation of denitrification rates in oxic soils due to scavenging ofintermediate nitric oxide[J].Soil Biology and Biochemistry,29(7):1067-1077.
Bridgham S D,Updegraff K,Pastor J.1998.Carbon,nitrogen,andphosphorus mineralization in northern wetlands[J].Ecology,79(5):1545-1561.
Butterbach-Bahl K,Willibald G,Papen H.2002.Soil core method for directsimultaneous determination of N2and N2O emissions from forest soils[J].Plant and Soil,240(1):105-116.
Cárdenas L M,Hawkins J M B,Chadwick D,et al.2003.Biogenic gasemissions from soils measured using a new automated laboratoryincubation system[J].Soil Biology and Biochemistry,35(6):867-870.
Caskey M H,Tiedje J M.1979.Evidence for clostridia as agents ofdissimilatory reduction of NO3-to NH4+in soils[J].Soil Science Societyof America Journal,43(5):931-936.
Cuhel J,Simek M,Laughlin R J,et al.2010.Insights into the effect of soilpH on N2O and N2emissions and denitrifier community size and activity[J].Applied and Environmental Microbiology,76(6):1870-1878.
Dannenmann M,Butterbach-Bahl K,Gasche R,et al.2008.Dinitrogenemissions and the N2:N2O emission ratio of a Rendzic Leptosol asinfluenced by pH and forest thinning[J].Soil Biology and Biochemistry,40(9):2317-2323.
Davidson E A,Seitzinger S.2006.The enigma of progress in denitrificationresearch[J].Ecological Applications,16(6):2057-2063.
范晓晖,朱兆良.2002.旱地土壤中的硝化—反硝化作用[J].土壤通报,33(5):385-391.Fan Xiaohui,Zhu Zhaoliang.2002.Nitrification anddenitrification in upland soils[J].Chinese Journal of Soil Science(inChinese),33(5):385-391.
Focht D D.1985.Differences in nitrogen-15enrichments of evolvednitrousoxide and dinitrogen and the question of auniform nitrate-15pool[J].Soil Science Society of America Journal,49(3):786-790.
Groffman P M,Altabet M A,Bohlke J K,et al.2006.Methods formeasuring denitrification:diverse approaches to a difficult problem[J].Ecological Applications,16(6):2091-2122.
Hutchinson G L,Davidson E A.1993.Processes for production andconsumption of gaseous nitrogen oxides in soil[M]//Harper L A,MosierA R,Duxbury J M,et al.Agricultural Ecosystem Effects on Trace Gasesand Global Climate Change.Madison,WI:ASA Special Publication,79-93.
IPCC.2007.Climate Change2007:The Physical Scientific Basis[M]//Contribution of Working Group1to the Fourth Assessment Report of theIntergovernmental Panel on Climate Chang.Solomon S,Qin D,ManningM,et al.,Eds.Cambridge,United Kingdom and New York,NY,USA:Cambridge University Press,996.
Jordan T E,Weller D E,Correll D L.1998.Denitrification in surface soils ofa riparian forest:Effects of water,nitrate,and sucrose[J].Soil Biologyand Biochemistry,30(7):833-843.
Klemedtsson L,Hansson G,Mosier A.1990.The use of acetylene for thequantification of N2production from biological processes in soil[M]//Revsbech J P,Sorensen J.Denitrification in Soil and Sediment.New York:Plenum Press,167-180.
Knowles R.1982.Denitrification[J].Microbiological Reviews,46(1):43-70.
李明,梁旺国,郑循华,等.2009.晋南地区典型盐碱地棉田的NO排放特征[J].气候与环境研究,14(3):318-328.Li Ming,Liang Wangguo,Zheng Xunhua,et al.2009.Characteristics of NO emission from typicalsaline soil of southern Shanxi cotton land[J].Climatic andEnvironmental Research(in Chinese),14(3):318-328.
李振高,潘映华,伍期途,等.1989.太湖地区水稻土优势反硝化细菌的数量、组成与酶活性[J].土壤学报,26(1):79-86.Li Zhengao,PanYinghua,Wu Qitu,et al.1989.Numbers,compositions and enzymeactivities of denitrifiers in paddy soils of Taihu Lake district[J].ActaPedologica Sinica(in Chinese),26(1):79-86.
McCready R G L,Gould W D,Brendregt R W.1983.Nitrogen isotopefractionation during the reduction of NO3-to NH4+by Desulfovibrio sp.[J].Canadian Journal of Microbiology,29(2):231-234.
Molstad L,D rsch P,Bakken L R.2007.Robotized incubation system formonitoring gases(O2,NO,N2O,N2)in denitrifying cultures[J].JournalMicrobiological Methods,71(3):202-211.
N mmik H.1956.Investigations on denitrification in soil[J].ActaAgriculturae Scandinavica,6(2):195-228.
Reddy K R,DeLaune R D.2008.Biogeochemistry of Wetlands:Scienceand Applications[M].CRC Press:Boca Raton:136-151.
Rice W A,Paul E A.1972.The organisms and biological processes involvedin asymbiotic nitrogen fixation in waterlogged soil amended with straw[J].Canadian Journal of Microbiology,18(6):715-723.
Robertson G P,Groffman P M.2007.Nitrogen Transformations[M]//PaulE A.Soil Microbiology,Ecology,and Biochemistry.3rd ed.Amsterdam,Boston,Heidelberg,London,New York,Oxford,Paris,San Diego,SanFrancisco,Singapore,Sydney,Tokyo:Elsevier,341-364.
Sahrawat K L,Keeney D R.1986.Nitrous oxide emission from soils[J].Advance in Soil Science,4:103-148.
Scheer C,Wassmann R,Butterbach-Bahl K,et al.2009.The relationshipbetween N2O,NO,and N2fluxes from fertilized and irrigated drylandsoils of the Aral Sea Basin,Uzbekistan[J].Plant Soil,314(1-2):273-283.
Scholefield D,Hawkins J M B,Jackson S M.1997a.Development of aHelium atmosphere soil incubation technique for direct measurement ofnitrous oxide and dinitrogen fluxes during denitrification[J].SoilBiology and Biochemistry,29(9-10):1345-1352.
Scholefield D,Hawkins J M B,Jackson S M.1997b.Use of a flowinghelium atmosphere incubation technique to measure the effects ofdenitrification controls applied to intact cores of a clay soil[J].SoilBiology and Biochemistry,29(9-10):1337-1344.
Simarmata T,Benkiser G,Ottow J C G.1993.Effect of an increasing carbon:nitrate-N ratio on the reliability of acetylene in blocking theN2O-reductase activity of denitrifying bacteria in soil[J].Biology andFertility of Soils,15(2):107-112.
Stefanson R C,Greenlan D J.1970.Measurement of nitrogen and nitrousoxide evolution from soil-plant systems using sealed growth chambers[J].Soil Science,109(3):203-206.
Swerts M,Uytterhoeven G,Merckx R,et al.1995.Semicontinuousmeasurement of soil atmosphere gases with gas-flow soil core method[J].Soil Science Society of America Journal,59(5):1336-1342.
Swerts M,Merckx R,Vlassak K.1996a.Denitrification,N2-fixation andfermentation during anaerobic incubation of soils amended with glucoseand nitrate[J].Biology and Fertility of Soils,23(3):229-235.
Swerts M,Merckx R,Vlassak K.1996b.Denitrification followed by N2fixation during anaerobic incubation[J].Soil Biology and Biochemistry,28(1):127-129.
Swerts M,Merckx R,Vlassak K.1996c.Influence of carbon availability onthe production of NO,N2O,N2,CO2by soil cores during anaerobicincubation[J].Plant and Soil,181(1):145-151.
Sparling G P,West A W.1988.Modifications to the fumigation-extractiontechnique to permit simultaneous extraction and estimation of soilmicrobial-C and microbial-N[J].Communications in Soil Science andPlant Analysis,19(3):327-344.
Tiedje J M.1988.Ecology of denitrification and dissimilatory nitratereduction to ammonium[M]//Zehnder A J B.Biology of AnaerobicMicroorganisms.New York:Wiley.
Wang R,Willibald G,Feng Q,et al.2011.Measurements of N2,N2O,NOand CO2emissions from soils with the gas-flow-soil-core technique[J].Environmental Science and Technology,45(14):6066-6072.
Weier K L,Doran J W,Power J F,et al.1993.Denitrification and thedinitrogen/nitrous oxide ratio as affected by soil water,availablecarbon,and nitrate[J].Soil Science Society of America Journal,57(1):66-72.
Yao H,Conrad R,Wassmann R,et al.1999.Effect of soil characteristics onsequential reduction and methane production in sixteen rice paddy soilsfrom China,the Philippines,and Italy[J].Biogeochemistry,47(3):269-295.
Yoshinari T,Knowles R.1976.Acetylene inhibition of nitrous oxidereduction by denitrifying bacteria[J].Biochemical and BiophysicalResearch Communications,69(3):705-710.
Zheng X H,Mei B L,Wang Y H,et al.2008.Quantification of N2O fluxesfrom soil-plant systems may be biased by the applied gas chromatographmethodology[J].Plant and Soil,311(1-2):211-234.
鲍士旦.2000.土壤农化分析[M].北京:中国农业出版社,49-56.BaoShidan.2000.Soil Agricultural Chemistry Analysis(in Chinese)[M].Beijing:China Agriculture Press,49-56.
Bollmann A,Conrad R.1997.Acetylene blockage technique leads tounderestimation of denitrification rates in oxic soils due to scavenging ofintermediate nitric oxide[J].Soil Biology and Biochemistry,29(7):1067-1077.
Bridgham S D,Updegraff K,Pastor J.1998.Carbon,nitrogen,andphosphorus mineralization in northern wetlands[J].Ecology,79(5):1545-1561.
Butterbach-Bahl K,Willibald G,Papen H.2002.Soil core method for directsimultaneous determination of N2and N2O emissions from forest soils[J].Plant and Soil,240(1):105-116.
Cárdenas L M,Hawkins J M B,Chadwick D,et al.2003.Biogenic gasemissions from soils measured using a new automated laboratoryincubation system[J].Soil Biology and Biochemistry,35(6):867-870.
Caskey M H,Tiedje J M.1979.Evidence for clostridia as agents ofdissimilatory reduction of NO3-to NH4+in soils[J].Soil Science Societyof America Journal,43(5):931-936.
Cuhel J,Simek M,Laughlin R J,et al.2010.Insights into the effect of soilpH on N2O and N2emissions and denitrifier community size and activity[J].Applied and Environmental Microbiology,76(6):1870-1878.
Dannenmann M,Butterbach-Bahl K,Gasche R,et al.2008.Dinitrogenemissions and the N2:N2O emission ratio of a Rendzic Leptosol asinfluenced by pH and forest thinning[J].Soil Biology and Biochemistry,40(9):2317-2323.
Davidson E A,Seitzinger S.2006.The enigma of progress in denitrificationresearch[J].Ecological Applications,16(6):2057-2063.
范晓晖,朱兆良.2002.旱地土壤中的硝化—反硝化作用[J].土壤通报,33(5):385-391.Fan Xiaohui,Zhu Zhaoliang.2002.Nitrification anddenitrification in upland soils[J].Chinese Journal of Soil Science(inChinese),33(5):385-391.
Focht D D.1985.Differences in nitrogen-15enrichments of evolvednitrousoxide and dinitrogen and the question of auniform nitrate-15pool[J].Soil Science Society of America Journal,49(3):786-790.
Groffman P M,Altabet M A,Bohlke J K,et al.2006.Methods formeasuring denitrification:diverse approaches to a difficult problem[J].Ecological Applications,16(6):2091-2122.
Hutchinson G L,Davidson E A.1993.Processes for production andconsumption of gaseous nitrogen oxides in soil[M]//Harper L A,MosierA R,Duxbury J M,et al.Agricultural Ecosystem Effects on Trace Gasesand Global Climate Change.Madison,WI:ASA Special Publication,79-93.
IPCC.2007.Climate Change2007:The Physical Scientific Basis[M]//Contribution of Working Group1to the Fourth Assessment Report of theIntergovernmental Panel on Climate Chang.Solomon S,Qin D,ManningM,et al.,Eds.Cambridge,United Kingdom and New York,NY,USA:Cambridge University Press,996.
Jordan T E,Weller D E,Correll D L.1998.Denitrification in surface soils ofa riparian forest:Effects of water,nitrate,and sucrose[J].Soil Biologyand Biochemistry,30(7):833-843.
Klemedtsson L,Hansson G,Mosier A.1990.The use of acetylene for thequantification of N2production from biological processes in soil[M]//Revsbech J P,Sorensen J.Denitrification in Soil and Sediment.New York:Plenum Press,167-180.
Knowles R.1982.Denitrification[J].Microbiological Reviews,46(1):43-70.
李明,梁旺国,郑循华,等.2009.晋南地区典型盐碱地棉田的NO排放特征[J].气候与环境研究,14(3):318-328.Li Ming,Liang Wangguo,Zheng Xunhua,et al.2009.Characteristics of NO emission from typicalsaline soil of southern Shanxi cotton land[J].Climatic andEnvironmental Research(in Chinese),14(3):318-328.
李振高,潘映华,伍期途,等.1989.太湖地区水稻土优势反硝化细菌的数量、组成与酶活性[J].土壤学报,26(1):79-86.Li Zhengao,PanYinghua,Wu Qitu,et al.1989.Numbers,compositions and enzymeactivities of denitrifiers in paddy soils of Taihu Lake district[J].ActaPedologica Sinica(in Chinese),26(1):79-86.
McCready R G L,Gould W D,Brendregt R W.1983.Nitrogen isotopefractionation during the reduction of NO3-to NH4+by Desulfovibrio sp.[J].Canadian Journal of Microbiology,29(2):231-234.
Molstad L,D rsch P,Bakken L R.2007.Robotized incubation system formonitoring gases(O2,NO,N2O,N2)in denitrifying cultures[J].JournalMicrobiological Methods,71(3):202-211.
N mmik H.1956.Investigations on denitrification in soil[J].ActaAgriculturae Scandinavica,6(2):195-228.
Reddy K R,DeLaune R D.2008.Biogeochemistry of Wetlands:Scienceand Applications[M].CRC Press:Boca Raton:136-151.
Rice W A,Paul E A.1972.The organisms and biological processes involvedin asymbiotic nitrogen fixation in waterlogged soil amended with straw[J].Canadian Journal of Microbiology,18(6):715-723.
Robertson G P,Groffman P M.2007.Nitrogen Transformations[M]//PaulE A.Soil Microbiology,Ecology,and Biochemistry.3rd ed.Amsterdam,Boston,Heidelberg,London,New York,Oxford,Paris,San Diego,SanFrancisco,Singapore,Sydney,Tokyo:Elsevier,341-364.
Sahrawat K L,Keeney D R.1986.Nitrous oxide emission from soils[J].Advance in Soil Science,4:103-148.
Scheer C,Wassmann R,Butterbach-Bahl K,et al.2009.The relationshipbetween N2O,NO,and N2fluxes from fertilized and irrigated drylandsoils of the Aral Sea Basin,Uzbekistan[J].Plant Soil,314(1-2):273-283.
Scholefield D,Hawkins J M B,Jackson S M.1997a.Development of aHelium atmosphere soil incubation technique for direct measurement ofnitrous oxide and dinitrogen fluxes during denitrification[J].SoilBiology and Biochemistry,29(9-10):1345-1352.
Scholefield D,Hawkins J M B,Jackson S M.1997b.Use of a flowinghelium atmosphere incubation technique to measure the effects ofdenitrification controls applied to intact cores of a clay soil[J].SoilBiology and Biochemistry,29(9-10):1337-1344.
Simarmata T,Benkiser G,Ottow J C G.1993.Effect of an increasing carbon:nitrate-N ratio on the reliability of acetylene in blocking theN2O-reductase activity of denitrifying bacteria in soil[J].Biology andFertility of Soils,15(2):107-112.
Stefanson R C,Greenlan D J.1970.Measurement of nitrogen and nitrousoxide evolution from soil-plant systems using sealed growth chambers[J].Soil Science,109(3):203-206.
Swerts M,Uytterhoeven G,Merckx R,et al.1995.Semicontinuousmeasurement of soil atmosphere gases with gas-flow soil core method[J].Soil Science Society of America Journal,59(5):1336-1342.
Swerts M,Merckx R,Vlassak K.1996a.Denitrification,N2-fixation andfermentation during anaerobic incubation of soils amended with glucoseand nitrate[J].Biology and Fertility of Soils,23(3):229-235.
Swerts M,Merckx R,Vlassak K.1996b.Denitrification followed by N2fixation during anaerobic incubation[J].Soil Biology and Biochemistry,28(1):127-129.
Swerts M,Merckx R,Vlassak K.1996c.Influence of carbon availability onthe production of NO,N2O,N2,CO2by soil cores during anaerobicincubation[J].Plant and Soil,181(1):145-151.
Sparling G P,West A W.1988.Modifications to the fumigation-extractiontechnique to permit simultaneous extraction and estimation of soilmicrobial-C and microbial-N[J].Communications in Soil Science andPlant Analysis,19(3):327-344.
Tiedje J M.1988.Ecology of denitrification and dissimilatory nitratereduction to ammonium[M]//Zehnder A J B.Biology of AnaerobicMicroorganisms.New York:Wiley.
Wang R,Willibald G,Feng Q,et al.2011.Measurements of N2,N2O,NOand CO2emissions from soils with the gas-flow-soil-core technique[J].Environmental Science and Technology,45(14):6066-6072.
Weier K L,Doran J W,Power J F,et al.1993.Denitrification and thedinitrogen/nitrous oxide ratio as affected by soil water,availablecarbon,and nitrate[J].Soil Science Society of America Journal,57(1):66-72.
Yao H,Conrad R,Wassmann R,et al.1999.Effect of soil characteristics onsequential reduction and methane production in sixteen rice paddy soilsfrom China,the Philippines,and Italy[J].Biogeochemistry,47(3):269-295.
Yoshinari T,Knowles R.1976.Acetylene inhibition of nitrous oxidereduction by denitrifying bacteria[J].Biochemical and BiophysicalResearch Communications,69(3):705-710.
Zheng X H,Mei B L,Wang Y H,et al.2008.Quantification of N2O fluxesfrom soil-plant systems may be biased by the applied gas chromatographmethodology[J].Plant and Soil,311(1-2):211-234.