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1.
王强盛  刘欣  许国春  余坤龙  张慧 《土壤》2023,55(6):1279-1288
稻田是大气温室气体甲烷(CH4)和氧化亚氮(N2O)的重要排放源, 稻田温室气体减排一直是生态农业研究的热点。目前, 采用水稻品种选择利用、水分控制管理、肥料运筹管理、耕作制度调整以及种养结合模式等方法来减少稻田温室气体排放有较好实践效应, 但不同稻田栽培环境(露地、网室)基础上的稻鸭共作对麦秸全量还田的稻田温室气体排放特征及相关土壤理化特性关联性的影响尚为少见。本研究采用裂区设计, 在两种栽培环境条件下, 以无鸭子放养的常规稻作和麦秸不还田为对照, 在等养分条件下分析麦秸全量还田与稻鸭共作模式对稻田土壤氧化还原电位、CH4排放量、产CH4潜力及CH4氧化能力、N2O排放量及N2O排放高峰期土壤反硝化酶活性、全球增温潜势、水稻产量的影响, 为稻田可持续生产和温室气体减排提供参考。结果表明, 麦秆还田增加了稻田产CH4潜力、提高了CH4排放量, 降低了稻田土壤反硝化酶活性、土壤氧化还原电位和N2O排放量, 整体上导致全球增温潜势上升96.89%~123.02%; 稻鸭共作模式, 由于鸭子的不间断活动提高了稻田土壤氧化还原电位, 降低了稻田产CH4潜力, 增强了稻田CH4氧化能力, 从而降低稻田CH4排放量, N2O排放量虽有提高, 整体上稻鸭共作模式的全球增温潜势较无鸭常规稻田下降8.72%~14.18%; 网室栽培模式显著提高了稻田土壤氧化还原电位, 降低稻田产CH4潜力、CH4氧化能力和土壤反硝化酶活性, 减少了稻田CH4和N2O排放量, 全球增温潜势降低6.35%~13.14%。本试验条件下, 稻田土壤的CH4氧化能力是产CH4潜力的2.21~3.81倍; 相同环境条件下, 稻鸭共作和麦秸还田均能增加水稻实际产量, 网室栽培的所有处理较相应的露地栽培减少了水稻实际产量1.19%~5.48%。本试验表明, 稻鸭共作和网室栽培可减缓全球增温潜势, 稻鸭共作和麦秸还田能够增加水稻实际产量。  相似文献   

2.
气候变化通过大气CO2浓度、温度和降雨的改变,直接或间接影响农田温室气体排放,研究未来气候情景下农田温室气体排放对实现农业碳减排具有重要意义。为探究气候变化背景下农田温室气体排放特征,该研究在长期田间定位试验基础上,利用当前大气CO2浓度与CO2浓度升高条件下旱作玉米农田温室气体排放通量的田间观测数据,采用“试错法”对DayCent模型进行校验,并利用校验后的模型,根据第六次国际耦合模式比较计划(Coupled Model Intercomparison Project phase 6,CMIP6)气候情景数据,预测未来SSP126与SSP245气候情景下旱地玉米农田温室气体排放通量。结果表明,DayCent模型对不同大气CO2浓度下N2O、CH4和CO2排放通量的模拟值与观测值高度一致,模拟效率(modeling efficiency,EF)分别为0.58~0.87、0.45~0.65和0.25~0.62,均方根误差(root mean square error,RMSE)分别为0.83~1.33、0.67~0.82和0.58~0.80 g/(hm2·d),决定系数(coefficient of determination,R2)分别为0.80~0.91、0.53~0.80和0.53~0.85。SSP126和SSP245气候情景下,在玉米单作种植模式下旱地农田N2O和CO2年排放量均呈现上升趋势,以2001—2020年农田温室气体排放通量为基准,到2060年N2O年排放量分别增加22.8%和24.9%,CO2年排放量分别增加6.7%和8.0%;旱地农田CH4年吸收量呈下降趋势,两个气候情景下分别减少13.6%和13.4%。未来气候情景下旱地农田仍是温室气体排放源,优化氮肥管理和农田耕作措施对实现温室气体减排具有重要意义,模拟结果可以为制定农业适应气候变化对策提供基础数据支持。  相似文献   

3.
为了研究耕作措施对双序列轮作农田土壤温室气体的排放及影响, 采用CO2分析仪、静态箱 气相色谱法在陇中黄土高原半干旱区对传统耕作不覆盖、免耕不覆盖、免耕秸秆覆盖和传统耕作+秸秆还田4种耕作措施下豆麦双序列轮作农田土壤温室气体(CO2、N2O和CH4)的排放及影响因素进行了连续测定和分析。结果表明: 测定期内4种耕作措施下农田土壤均表现为CO2源、N2O源和CH4净吸收汇; 除传统耕作不覆盖措施, 其他3种耕作措施不同程度地减少了2种轮作序列土壤的N2O排放通量, 并显著增加了土壤对CH4的吸收。CO2和N2O的排放通量分别与地表、地下5 cm处、地下10 cm处的土壤温度呈极显著和显著正相关关系, 相关系数分别为0.92**和0.89**、0.95**和0.91**、0.77*和0.62*; 而CH4吸收通量与不同地层的温度之间无明显的相关关系; CO2和CH4的通量与0~5 cm、5~10 cm的土壤含水量均呈显著正相关关系, 相关系数分别为0.69*和0.72*、0.77*和0.64*, 而与10~30 cm土壤含水量无明显相关关系; N2O排放通量与各层次的土壤含水量之间均呈不显著负相关关系。对2种轮作序列各处理下土壤中排放的3种温室气体的增温潜势计算综合得出: 4种耕作措施中, 免耕不覆盖处理可相对减少土壤温室气体的排放量, 进而降低温室效应。  相似文献   

4.
通过设置在甘肃省定西市李家堡镇的不同耕作措施试验, 利用CO2分析仪、静态箱-气相色谱法对双序列轮作次序下春小麦地、豌豆地生育期内CO2、CH4和N2O通量进行了测定。试验结果表明: 4种耕作措施下春小麦地和豌豆地在生育期内均表现为CO2源、N2O源和CH4汇的功能。传统耕作不覆盖、免耕不覆盖、免耕秸秆覆盖和传统耕作结合秸秆还田下, 春小麦生育期内平均土壤CO2通量(μmol·m-2·s-1)分别为0.203 6、0.221 2、0.241 8、0.224 9, CH4通量(mg·m-2·h-1)分别为-0.041 6、-0.078 0、-0.081 8、-0.053 7, N2O通量(mg·m-2·h-1)分别为0.089 1、0.069 2、0.046 1、0.065 6; 豌豆生育期内平均土壤CO2通量(μmol·m-2·s-1)分别为0.273 6、0.261 6、0.218 1、0.236 0, CH4通量(mg·m-2·h-1)分别为-0.055 0、-0.073 7、-0.066 2、-0.054 5, N2O通量(mg·m-2·h-1)分别为0.123 4、0.084 7、0.080 6、0.035 0。少免耕及小麦秸秆覆盖有利于减少土壤CO2排放通量, 免耕不覆盖、免耕秸秆覆盖及传统耕作结合秸秆还田均能不同程度地增加CH4吸收通量、减少N2O排放通量。综合来看, 免耕不覆盖、免耕秸秆覆盖和传统耕作结合秸秆还田3种保护性耕作措施有助于减少土壤温室气体的排放量。春小麦地CO2通量随着土壤温度、土壤含水量的逐渐升高而增大; CH4吸收通量随着土壤含水量的逐渐升高而增大, 而随着土壤温度的逐渐升高而减小。豌豆地CO2通量的变化与土壤含水量存在极显著正相关关系; 而春小麦地N2O通量则与平均土壤温度呈显著正相关, 豌豆地则为极显著正相关。  相似文献   

5.
开展大气CO2 浓度升高对华北夏玉米地温室气体排放的影响可为未来气候变化下农业温室气体减排提供依据。研究基于已稳定运行10 年的华北典型一年两季自由大气CO2 富集平台进行,于 2017 年设置2 个处理,即常规浓度CO2(aCO2,平均400 μmol·mol-1)和高浓度CO2(eCO2,550 μmol·mol-1),2018 年在不同CO2 浓度下增设低氮(LN)和高氮(HN)水平下的不同CO2 浓度处理(即aCO2-LN、aCO2-HN、eCO2-LN、eCO2-HN)开展试验,监测和分析不同处理下土壤CO2 及N2O 排放通量特征,结合土壤硝化潜势和反硝化潜势测定解析N2O排放量变化的可能原因。结果表明,eCO2 下夏玉米生育期农田N2O 和CO2 累积排放量分别比aCO2 下显著增加45.5% ~ 65.9% 和16.7% ~ 19.2%;N2O 排放增加主要发生在施肥、灌溉和降雨后,而土壤CO2 在玉米营养生长期排放量较高。eCO2 条件下土壤硝化潜势和反硝化潜势分别比aCO2 下提高了36.4% 和59.0%,对土壤N2O 排放有贡献潜力。eCO2 下,N2O 减排需结合排放机理采取合理的田间管理和水肥调控措施。  相似文献   

6.
夏季猪场污水贮存过程中CO2、CH4排放试验   总被引:1,自引:0,他引:1       下载免费PDF全文
猪场粪污是重要的温室气体排放源,针对中国缺乏猪场污水贮存过程中温室气体排放参数的问题,该文选择温度较高的夏季,利用动态箱法于2007年6月对猪场的三格式化粪池进行了CO<2、CH4气体排放测试。测试结果表明:当大气平均温度为28.4℃时,86%的温室气体排放源于一级和二级化粪池,一级、二级和三级化粪池的温室气体排放通量分别为407.5、383.0、127.7 g/(m2?h)二氧化碳当量;CH4是本污水贮存单元中产生的主要的温室气体,一、二、三级化粪池排放的温室气体总量中,CH4排放的贡献率分别为95%、96%、95%,控制一、二级化粪池甲烷排放将大幅度减少猪场污水温室气体排放  相似文献   

7.
为了研究生物炭及秸秆还田对干旱区玉米农田温室气体通量的影响,以内蒙古科尔沁地区玉米农田为试验对象,采用静态箱-气相色谱法对分别施入生物炭0 t·hm-2(CK)、15 t·hm-2(C15)、30 t·hm-2(C30)、45 t·hm-2(C45)及秸秆还田(SNPK)的土壤进行温室气体(CO2、CH4和N2O)通量的原位观测,并估算生长季CH4和N2O的综合增温潜势(GWP)与排放强度(GHGI)。结果表明:添加生物炭能够显著减少土壤CO2和N2O的排放量,并促进土壤对CH4的吸收作用。其中处理C15对CO2的减排效果最好,与对照相比CO2排放量降低21.16%。随着施入生物炭量的增加,生物炭对N2O排放的抑制作用不断增强,处理C45对减排效果最好,与对照相比N2O排放量降低86.25%。处理C15对土壤吸收CH4的促进效果最好,CH4吸收量增加56.62%;处理C45对CH4的排放有促进作用,使生长季土壤吸收CH4减少81.36%。SNPK对温室气体的减排作用接近处理C15。添加生物炭和秸秆还田对提高玉米产量和降低农田GWP与GHGI均有显著效果,施用生物炭及秸秆还田均有效提高了科尔沁地区的玉米产量,且玉米产量随着施入生物炭含量的增大而提升。从GWP上来看,施用15 t·hm-2生物炭对温室气体减排的整体效果最好。从GHGI上来看,施用生物炭及秸秆还田均具有一定的经济效益和减排意义,其中施用15 t·hm-2生物炭的综合效益最高。因此综合经济效益与环境因素,建议科尔沁地区农田在种植玉米时添加15 t·hm-2生物炭,如不具备购买生物炭条件,可以考虑秸秆还田来实现玉米增产与温室气体减排。  相似文献   

8.
减量施氮与大豆间作对蔗田土壤温室气体排放的影响   总被引:3,自引:2,他引:1  
采用静态箱 气相色谱法对常规施氮(N2, 525 kg·hm-2)y和减量施氮(N1, 300 kg·hm-2)处理下甘蔗与大豆按行数比1∶1(SB1)和1∶2(SB2)间作、甘蔗单作(MS)、大豆单作(MB)种植模式下蔗田土壤CO2、N2O、CH4排放通量及土地当量比(LER)进行观测和对比分析, 以探讨不同间作模式及施氮水平下甘蔗//大豆间作农田土壤温室气体排放的动态变化规律及对作物产量的影响, 为制定农田温室气体减排措施提供合理的依据。研究结果表明, 减量施氮处理甘蔗//大豆(1∶2)间作模式(SB2-N1)农田土壤CO2排放总量较甘蔗单作(MS)显著降低35.58%, N2O累积排放总量较甘蔗单作降低56.36%, CH4累积排放总量较甘蔗单作升高7.02%; 不同种植模式和施氮处理蔗田土壤均表现为CO2和N2O的排放源, CH4吸收汇, 追施氮肥后土壤对CH4的吸收速率降低, 但CO2和N2O的排放速率增加。MS-N1、SB1-N1、SB2-N1、MS-N2、SB1-N2、SB2-N2和MB处理土壤CO2年累积排放总量(kg·hm-2·a-1)分别为5 096.89、6 422.69、3 283.20、4 103.29、4 475.84、4 775.31和4 780.35, 土壤N2O年累积排放总量(kg·hm-2·a-1)分别为4.61、5.11、2.15、3.13、3.72、5.60和3.11, 土壤CH4年累积排放总量(kg·hm-2·a-1)分别为 13.68、 21.78、 12.72、 5.53、 11.36、 4.77和 9.97。甘蔗//大豆间作系统2009-2012年土地当量比(LER)均大于1, 且减量施氮水平下, 甘蔗//大豆(1∶2)间作模式优势最明显。  相似文献   

9.
有机农业发展的低碳机理分析   总被引:1,自引:0,他引:1  
温室气体排放引起的全球气候变暖是人类关注的环境热点问题之一。本文从农业生态系统影响全球变暖的主要温室气体(CO2、N2O 和CH4)的产生和排放出发, 探讨有机农业在生产减排和土壤固碳方面的机理。研究发现相对于常规农作而言, 有机农业在减排和固碳方面具有很大优势和潜力; 然而, 从长期来看, 通过土壤固碳减少大气温室气体的排放不是无限制的, 到一定程度后会达到一个平衡。因此, 更多的有效固碳途径和管理措施有待于进一步研究。同时, 从低碳理念出发, 强调中国加强有机农业环境效益研究的必要性。  相似文献   

10.
探讨有机物料还田对冬小麦田温室气体排放特性的影响,对提高经济效应和环境效应有积极意义。本研究应用静态箱-气相色谱法对秸秆还田(J)、秸秆还田+牛粪(JF)和秸秆还田+菌渣(JZ)3种有机物料还田下分别施氮肥243 kg (N)·hm-2(减氮10%,N1)、216 kg (N)·hm-2(减氮20%,N2)对冬小麦农田N2O、CO2和CH4的排放通量进行监测,探讨了不同施肥措施对麦田温室气体累积排放量、增温潜势的影响。试验期间同步记录每项农事活动机械燃油量、施肥量和灌溉量,测定产量,地上部生物量,估算农田碳截留。结果表明,冬小麦农田土壤N2O和CO2是排放源,是CH4的吸收汇,氮肥施入、灌溉以及强降水促进了土壤N2O和CO2的生成,却弱化了CH4作为大气吸收汇的特征。牛粪+秸秆(JF)处理N2O和CO2排放总量最高,分别为3.5 kg (N2O-N)·hm-2和19 689.67 kg (CO2-C)·hm-2,但CH4的吸收值最大,为5.33 kg (CH4-C)·hm-2,均显著高于菌渣+秸秆(JZ)和秸秆(J)处理(P<0.05);各处理N2O和CO2的总量随施氮量的增加呈升高趋势,CH4的总量随施氮量的增加而呈降低趋势。JFN2、JN2和JZN2处理农田综合增温潜势(GWP)均为负值,表明有机物料还田且减氮20%条件下农田生态系统为大气的碳汇,麦季净截留碳1 038~2 024 kg·hm-2,其他处理GWP值均为正。JZN2处理小麦产量为8 061 kg·hm-2,显著高于JFN2处理(P<0.05)。综上所述,JZN2处理不仅能够保证小麦产量,且对环境效应最有利,为本区域冬小麦较优的施肥管理模式。  相似文献   

11.
Peatlands play an important role in emissions of the greenhouse gases CO2, CH4 and N2O, which are produced during mineralization of the peat organic matter. To examine the influence of soil type (fen, bog soil) and environmental factors (temperature, groundwater level), emission of CO2, CH4 and N2O and soil temperature and groundwater level were measured weekly or biweekly in loco over a one-year period at four sites located in Ljubljana Marsh, Slovenia using the static chamber technique. The study involved two fen and two bog soils differing in organic carbon and nitrogen content, pH, bulk density, water holding capacity and groundwater level. The lowest CO2 fluxes occurred during the winter, fluxes of N2O were highest during summer and early spring (February, March) and fluxes of CH4 were highest during autumn. The temporal variation in CO2 fluxes could be explained by seasonal temperature variations, whereas CH4 and N2O fluxes could be correlated to groundwater level and soil carbon content. The experimental sites were net sources of measured greenhouse gases except for the drained bog site, which was a net sink of CH4. The mean fluxes of CO2 ranged between 139 mg m−2 h−1 in the undrained bog and 206 mg m−2 h−1 in the drained fen; mean fluxes of CH4 were between −0.04 mg m−2 h−1 in the drained bog and 0.05 mg m−2 h−1 in the drained fen; and mean fluxes of N2O were between 0.43 mg m−2 h−1 in the drained fen and 1.03 mg m−2 h−1 in the drained bog. These results indicate that the examined peatlands emit similar amounts of CO2 and CH4 to peatlands in Central and Northern Europe and significantly higher amounts of N2O.  相似文献   

12.
We examined net greenhouse gas exchange at the soil surface in deciduous forests on soils with high organic contents. Fluxes of CO2, CH4 and N2O were measured using dark static chambers for two consecutive years in three different forest types; (i) a drained and medium productivity site dominated by birch, (ii) a drained and highly productive site dominated by alder and (iii) an undrained and highly productive site dominated by alder. Although the drained sites had shallow mean groundwater tables (15 and 18 cm, respectively) their average annual rates of forest floor CO2 release were almost twice as high compared to the undrained site (1.9±0.4 and 1.7±0.3, compared to 1.0±0.2 kg CO2 m−2 yr−1). The average annual CH4 emission was almost 10 times larger at the undrained site (7.6±3.1 compared to 0.9±0.5 g CH4 m−2 yr−1 for the two drained sites). The average annual N2O emissions at the undrained site (0.1±0.05 g N2O m−2 yr−1) were lower than at the drained sites, and the emissions were almost five times higher at the drained alder site than at the drained birch site (0.9±0.35 compared to 0.2±0.11 g N2O m−2 yr−1). The temporal variation in forest floor CO2 release could be explained to a large extent by differences in groundwater table and air temperature, but little of the variation in the CH4 and N2O fluxes could be explained by these variables. The measured soil variables were only significant to explain for the within-site spatial variation in CH4 and N2O fluxes at the undrained swamp, and dark forest floor CO2 release was not explained by these variables at any site. The between-site spatial variation was attributed to variations in drainage, groundwater level position, productivity and tree species for all three gases. The results indicate that N2O emissions are of greater importance for the net greenhouse gas exchange at deciduous drained forest sites than at coniferous drained forest sites.  相似文献   

13.
水分类型对土壤排放的温室气体组成和综合温室效应的影响   总被引:36,自引:2,他引:34  
蔡祖聪 《土壤学报》1999,36(4):484-491
实验室研究表明,土壤排放出的温室气体(CO2、CH4和N2O)组成及总理显著地受土壤水分类型和施用秸秆的影响。连续淹水条件下,土壤仅排放微理的N2O,但排放出大量的C睡C敢条件下,土壤不排放C上键合的但排放出大量的N2O;虽然淹水的土壤排水促进N2O排放,但显著抑制CH4的排放,淹水好气交替处理的土壤其排放的CO2、CH4和N2O均在好气和连续淹水之间。根据各种温室产生温室效应的相对潜力,计算土壤  相似文献   

14.
To determine the sum of ‘direct’ and ‘indirect’ effects of climatic change on enchytraeid activity and C fluxes from an organic soil we assessed the influence of temperature (4, 10 and 15 °C incubations) on enchytraeid populations and soil CO2 and CH4 fluxes over 116 days. Moisture was maintained at 60% of soil dry weight during the experimental period and measurements of enchytraeid biomass and numbers, and CO2 and CH4 fluxes were made after 3, 16, 33, 44, 65, 86 and 116 days. Enchytraeid population numbers and biomass increased in all temperature treatments with the greatest increase produced at 15 °C (to over threefold initial values by day 86). Results also showed that enchytraeid activity increased CO2 fluxes by 10.7±4.5, 3.4±4.0 and 26.8±2.6% in 4, 10 and 15 °C treatments, respectively, with the greatest CO2 production observed at 15 °C for the entire 116 day incubation period (P<0.05). The soil respiratory quotient analyses at lower temperatures (i.e. 4-10 °C) gave a Q10 of 1.7 and 1.9 with and without enchytraeids, respectively. At temperatures above 10 °C (i.e. 10-15 °C) Q10 significantly increased (P<0.01) and was 25% greater in the presence of enchytraeids (Q10=3.4) than without (Q10=2.6). In contrast to CO2 production, no significant relationships were observed between net CH4 fluxes and temperature and only time showed a significant effect on CH4 production (P<0.01).Total soil CO2 production was positively linked with enchytraeid biomass and mean soil CO2-C production was 77.01±6.05 CO2-C μg mg enchytraeid tissue−1 day−1 irrespective of temperature treatment. This positive relationship was used to build a two step regression model to estimate the effects of temperature on enchytraeid biomass and soil CO2 respiration in the field. Predictions of potential CO2 production were made using enchytraeid biomass data obtained in the field from two upland grassland sites (Sourhope and Great Dun Fell at the Moor House Nature Reserve, both in the UK). The findings of this work suggest that a 5 °C increase in atmospheric temperature above mean ambient temperature could have the potential to produce a significant increase in enchytraeid biomass resulting in a near twofold increase in soil CO2 release from both soil types. The interaction between temperature and soil biology will clearly be an important determinant of soil respiration responses to global warming.  相似文献   

15.
利用一种带全自动预GC浓缩接口(PreCon)的同位素质谱计,可以高精度地测定大气浓度下N2O、CH4或CO2中的碳、氮、氧稳定性同位素比值。本文就采样、浓缩和质谱测定技术进行了一系列方法试验,测得的结果准确可靠,证实方法是可行的。其可应用于空气质量监测、以及大气化学、植物的呼吸作用和土壤气体发生的研究。  相似文献   

16.
Emissions of N2O and CH4 and CH4 oxidation rates were measured from Lolium perenne swards in a short-term study under ambient (36 Pa) and elevated (60 Pa) atmospheric CO2 at the Free Air Carbon dioxide Enrichment experiment, Eschikon, Switzerland. Elevated pCO2 increased (P<0.05) N2O emissions from high N fertilised (11.2 g N m−2) swards by 69%, but had no significant effect on net emissions of CH4. Application of 13C-CH4 (11 μl l−1; 11 at.% excess 13C) to closed chamber headspaces in microplots enabled determination of rates of 13C-CH4 oxidation even when net CH4 fluxes from main plots were positive. We found a significant interaction between fertiliser application rate and atmospheric pCO2 on 13C-CH4 oxidation rates that was attributed to differences in gross nitrification rates and C and N availability. CH4 oxidation was slower and thought to be temporarily inhibited in the high N ambient pCO2 sward. The most rapid CH4 oxidation of 14.6 μg 13C-CH4 m−2 h−1 was measured in the high fertilised elevated pCO2 sward, and we concluded that either elevated pCO2 had a stimulatory effect on CH4 oxidation or inhibition of oxidation following fertiliser application was lowered under elevated pCO2. Application of 14NH415NO3 and 15NH415NO3 (10 at.% excess 15N) to different replicates enabled determination of the respective contributions of nitrification and denitrification to N2O emissions. Inhibition of CH4 oxidation in the high fertilised ambient pCO2 sward, due to competition between NH3 and CH4 for methane monooxygenase enzymes or toxic effects of NH2OH or NO2 produced during nitrification, was hypothesised to increase gross nitrification (12.0 mg N kg dry soil−1) and N2O emissions during nitrification (327 mg 15N-N2O m−2 over 11 d). Our results indicate that increasing atmospheric concentrations of CO2 may increase emissions of N2O by denitrification, lower nitrification rates and either increase or decrease the ability of soil to act as a sink for atmospheric CH4 depending on fertiliser management.  相似文献   

17.
温室CO2气体浓度环境自动调控系统的研究   总被引:5,自引:1,他引:4  
为了改善现代温室内气体环境的质量,提高温室的生产产量和产品品质,介绍一种新型温室CO2浓度自动调控系统,并运用射流理论,分析研究了系统的设计原理和方法,对系统的工作性能也作了相应的对比实验研究,结果表明该系统具有结构简单、自动控制性能好、造价低、运行经济可靠、补充CO2速度快、CO2浓度和气体流速分布均匀、增产效果和经济效益明显等特点。  相似文献   

18.
皖中沿江平原水稻田CH_4和N_2O排放估算及其影响因素分析   总被引:5,自引:0,他引:5  
利用DNDC9.3模型对研究区域水稻田排放的CH4和N2O通量进行模拟和定量估算,并对其影响因素进行分析。研究选取皖中沿江平原内具有典型代表性的长丰县水稻田为实验地区,利用DNDC9.3模型对该县内12个试验样点2008年的CH4和N2O排放量进行估算分析,并对其做敏感性实验分析。结果表明:1)长丰县水稻田2008年CH4和N2O年排放量分别为C 1.82×10-2 Tg和N 3.03×10-4 Tg;2)由敏感性分析实验得:CH4排放水平和气温、土壤pH和SOC呈正相关关系;N2O排放水平和气温、雨水中氮含量呈正相关关系,对SOC、土壤pH变化也较为敏感。  相似文献   

19.
In temperate regions, climate change is predicted to increase annual mean temperature and intensify the duration and frequency of summer droughts, which together with elevated atmospheric carbon dioxide (CO2) concentrations, may affect the exchange of nitrous oxide (N2O) and methane (CH4) between terrestrial ecosystems and the atmosphere. We report results from the CLIMAITE experiment, where the effects of these three climate change parameters were investigated solely and in all combinations in a temperate heathland. Field measurements of N2O and CH4 fluxes took place 1-2 years after the climate change manipulations were initiated. The soil was generally a net sink for atmospheric CH4. Elevated temperature (T) increased the CH4 uptake by on average 10 μg C m−2 h−1, corresponding to a rise in the uptake rate of about 20%. However, during winter elevated CO2 (CO2) reduced the CH4 uptake, which outweighed the positive effect of warming when analyzed across the study period. Emissions of N2O were generally low (<10 μg N m−2 h−1). As single experimental factors, elevated CO2, temperature and summer drought (D) had no major effect on the N2O fluxes, but the combination of CO2 and warming (TCO2) stimulated N2O emission, whereas the N2O emission ceased when CO2 was combined with drought (DCO2). We suggest that these N2O responses are related to increased rhizodeposition under elevated CO2 combined with increased and reduced nitrogen turnover rates caused by warming and drought, respectively. The N2O flux in the multifactor treatment TDCO2 was not different from the ambient control treatment. Overall, our study suggests that in the future, CH4 uptake may increase slightly, while N2O emission will remain unchanged in temperate ecosystems on well-aerated soils. However, we propose that continued exposure to altered climate could potentially change the greenhouse gas flux pattern in the investigated heathland.  相似文献   

20.
Peatlands typically exhibit significant spatial heterogeneity which can lead to large uncertainties when catchment scale greenhouse gas fluxes are extrapolated from chamber measurements (generally <1 m2). Here we examined the underlying environmental and vegetation characteristics which led to within-site variability in both CH4 and N2O emissions and the importance of such variability in up-scaling. We also consider within-site variation in the controls of temporal dynamics. Net annual emissions (and coefficients of variation) for CH4 and N2O were 1.06 kg ha−1 y−1 (300%) and 0.02 kg ha−1 y−1 (410%), respectively. The riparian zone was a significant CH4 hotspot contributing ∼12% of the total catchment emissions whilst covering only ∼0.5% of the catchment area. In contrast to many other studies we found smaller CH4 emissions and greater uptake in chambers containing either sedges or rushes. We also found clear differences in the drivers of temporal CH4 dynamics across the site, e.g. water table was important only in chambers which did not contain aerenchymous plants. We suggest that depending on the heterogeneity of the site, flux models could be improved by incorporating a number of spatially distinct sub-models, rather than a single model parameterized using whole-catchment averages.  相似文献   

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