Preliminary studies on methane flux from the ornithogenic soils on Xi-Sha atoll, South China Sea

IntroductionMethane ( CH4) is a radiatively active trace gas ,contributing approximately 20 % to global warming(Bouwman, 1990) . An increasing concentration in theatmosphere, and ill-defined sink and source strengths haveled to a proliferation of the stud…     

人为干扰对闽江河口短叶茳芏湿地N2O排放的影响

采用静态箱-气相色谱法和浮箱-气相色谱法,分别对闽江河口潮间带短叶茳芏(Cyperus malaccensis var. brevifolius)湿地、互花米草(Spartina alterniflora Loisel)入侵斑块湿地、输入养分的短叶茳芏湿地和踩踏形成的裸露湿地N2O通量进行测定,以研究不同的人为干扰方式对短叶茳芏湿地N2O通量的影响.结果表明:互花米草入侵斑块N2O通量[15.37μg/(m2·h)]低于短叶茳芏湿地[18.77μg/(m2·h)],互花米草入侵降低了短叶茳芏湿地的N2O排放,互花米草入侵的减排作用与潮汐关系密切,而与植物生长季节关系不明显;养分输入显著增加了短叶茳芏湿地N2O排放.秋季,养分输入后,短叶茳芏湿地N2O排放平均值为163.72μg/(m2·h),春季,养分输入后,高潮淹水时和高潮无淹水时,短叶茳芏湿地N2O排放平均值分别为227.62μg/(m2·h)和1178.64μg/(m2·h),极显著高于对照,高潮淹水时N2O排放峰值出现较高潮无淹水时早,N2O通量远低于高潮无淹水时;踩踏形成的裸露湿地N2O平均通量为-0.76μg/(m2·h),表明踩踏降低了短叶茳芏湿地N2O通量,但降低程度因植物的生长季节和潮汐环境的差异而不同.     

北京地区暖温带森林土壤温室气体排放规律

本研究利用静态箱法在北京市东灵山暖温带森林生长期选择3种不同类型的森林(阔叶混交林、辽东栎林和油松林)的土壤进行了温室气体(CH₄、CO₂和N₂O)排放规律的野外原位观测.研究结果表明:暖温带主要代表森林类型的土壤作为CH₄的汇吸收大气中的CH₄,同时作为CO₂和N₂O的源向大气排放.观测结果显示:不同的森林土壤类型其温室气体排放通量、范围各不相同,阔叶混交林土壤CH₄、CO₂和N₂O通量范围分别是:42～103μg/(m²·h),15～344mg/(m²·h)和-61～101μg/(m²·h);辽东栎林土壤3种气体通量范围分别是:13～182 μg/(m²·h),23～380mg/(m²·h)和-15～183 μg/(m²·h);油松林土壤3种气体通量范围分别是:12～128 μg/(m²·h),15～292mg/(m²·h) 和 -94～153 μg/(m²·h).观测期内阔叶混交林土壤CH₄、CO₂和N₂O平均通量分别是:-66 μg/(m²·h),145mg/(m²·h)和22 μg/(m²·h);辽东栎林土壤3种气体平均通量分别是:-67 μg/(m²·h),146mg/(m²·h)和45μg/(m²·h);油松林土壤3种气体平均通量分别是:-79 μg/(m²·h),150mg/(m²·h)和31μg/(m²·h).本研究估算了不同类型的森林土壤不同的温室气体生长期内的排放总量,阔叶混交林土壤CH₄、CO₂和N₂O排放总量分别是:-5.34kg/(hm²·a),13.9Mg/(hm²·a) 和2.58kg/(hm²·a); 辽东栎林土壤3种气体排放总量分别是:-6.20kg/(hm²·a), 14.07Mg/(hm²·a)和4.19kg/(hm²·a); 油松林土壤3种气体排放总量分别是-6.85kg/(hm²·a), 15.71Mg/(hm²·a)和4.30kg/(hm²·a).     

三江平原沼泽湿地N2O浓度与排放特征初步研究

2001年8月到9月在三江平原沼泽湿地进行N₂O的原位静态箱观测.结果发现近地气层N₂O平均浓度为281.7×10^-9m³/m³,低于大气背景浓度,说明沼泽湿地可能是人类目前了解较少但很重要的N₂O汇.选取积水状况和地表植被不同的毛果苔草沼泽、小叶章湿草甸(Ⅰ,Ⅱ)以及作为对照的小麦休耕地进行观测,发现4个地点的N₂O排放日变化形式不完全相同,除小麦田全天持续排放N₂O外,其余各点一天当中均出现排放与吸收交替出现的情况.温度是影响排放模式的主要因素.观测期内毛果苔草沼泽、小叶章湿草甸(Ⅰ,Ⅱ)和小麦休耕地N₂O的平均排放强度分别为0.22μg/(m²·h),1.75μg/(m²·h),1.31μg/(m²·h)和4.86μg/(m²·h).氧化还原电位是决定沼泽湿地N₂O排放特征的关键因子,地表积水情况和土壤水分状况则是影响N₂O排放的另一重要因素.     

Effect of fertilizer and water content on N2O emission from three plantation soils in South China

Introduction Nitrousoxide(N2O)isoneofthemostimportantgreen housegases,whichcontributestoglobalwarmingand consumptionofO3inthestratosphere(Breuer,2000,Solomon,1999).N2Oconcentrationincreasesatarateof0.25%peryear,57%ofwhichisderivedfromthesoildue tonitrific…     

中国草地N2O通量日变化观测对比研究

研究分析了我国20世纪90年代以来科学工作者利用静态箱-气相色谱法对内蒙古呼伦贝尔草原和锡林郭勒草原、青藏高寒草原等不同草原类型所开展的日变化通量观测数据并进行了对比分析研究.结果表明:我国草地N2O通量的日变化规律明显,日变化形式呈多峰型,我国草地均表现为N2O排放源,日均通量的对比顺序是:贝加尔针茅草甸草原>羊草草甸草原>羊草典型草原>高寒草甸[(42.82±15.96)>(29.17±13.03)>(4.91±2.12)>(0.89±0.67)μg/(m2?h)];10:00~14:00和夜间0:00左右所观测的N2O通量均可代表当日平均通量;夜间N2O的排放对整个日通量有重要贡献,其排放量占到全日排放总量的46%以上,草地夜间N2O的排放通量应该受到重视.另外,本文讨论了水分和温度作为主要环境因子对N2O通量日变化的影响,以及不同植被类型和人类活动(放牧和刈割)对N2O通量的日变化的影响.     

三江平原泥炭沼泽湿地N2O排放通量及影响因子

运用静态暗箱-气相色谱法观测了三江平原毛苔草泥炭沼泽湿地植物生长季N2O排放通量,并分析了其关键影响因子.结果表明:生长季N2O排放通量季节变化动态明显,最大值出现在7月上旬;平均排放通量为76.77μg/(m2·h),高于潜育沼泽湿地[20~60μg/(m2·h), 2002~2005].N2O排放通量与土壤温度存在极显著指数关系(P<0.01),且随土壤深度(土壤10cm以下)的增加相关关系逐渐减弱;与水位呈极显著负相关关系(P<0.01);另外,植被是影响N2O排放的主要生物因子,有植被参与的N2O排放是无植被的1.7倍.总之,水位和土壤温度是控制泥炭沼泽N2O排放呈明显季节变化的主要因素,而土壤水文物理特性的差异是引起泥炭沼泽N2O排放高于潜育沼泽的主要原因.经初步估算,三江平原泥炭沼泽每年植物生长季N2O排放总量约为72.9Mg,表明泥炭沼泽湿地在生长季是重要的N2O潜在排放源.     

太湖地区湖水与河水中溶解N2O及其排放

水体是N₂O排放的重要来源.2000-09～2001-09,每月2次采样(重复3次)连续监测太湖地区太湖和大运河水体N₂O排放通量和水中溶解的N₂O浓度,还同时监测不同深度水样中的N₂O浓度.结果表明,太湖N₂O-N的年均排放通量为3.53 μg/(m²·h),而大运河已高达122.5,μg/(m²·h).太湖湖水中溶解N₂O-N浓度为0.36μg/L,大运河河水中浓度高达11.31μg/L,浅水型水体是N2O排放的源.结果还表明,不同深度水中N2O浓度差异不明显,而时间差异显著.水面N2O的排放通量和水中溶解的N2O浓度呈显著正相关关系,二者又都与水温呈显著正相关. .     

四川桤柏混交林土壤N2O排放的实测与模拟

采用静态箱-气相色谱法对川中丘陵区桤柏混交林土壤N2O排放进行了连续两年的测定.通过与Forest-DNDC模型模拟进行对比分析,结果表明,模型能够较好地模拟林地土壤N2O排放.2005和2006年模型模拟的土壤N2O年平均排放速率为15.02,14.03mg/(m2×h),分别为实际观测值的85.7%和87.5%.2005和2006年的实际观测值与模型模拟值之间差异均不显著(P>0.05),模拟有效系数分别为0.56和0.51.以2005年降雨量和气温为基准利用模型进行情景分析,结果表明,本地区降雨量在±30%范围内变化时,林地土壤N2O排放量的变化幅度不超过25%;气温在±3℃范围内变化时,林地土壤N2O排放量的变化幅度不超过10%.     

Surface-exchange of NOx and NH3 above a winter wheat field in the Yangtze Delta, China

Introduction N itrogen oxides (N O x=N O N O 2) in the troposphere are m ainly derived from fuel com bustion, soil-biogenic em issions, biom ass burning, and lightning (Finlayson-Pitts et al., 1986; H am eed and D ignon, 1988; Levy et al., 1989; Logan, 1…     

南京典型水体春季温室气体排放特征研究

利用静态箱-气相色谱法对南京4条河流(内秦淮河、外秦淮河、金川河、团结河)和1座水库(丁解水库)的春季水-气界面CO2、CH4、N2O 3种温室气体通量进行包括昼夜变化的持续观测,对其变化趋势及影响因素加以分析.结果表明,春季团结河CO2和CH4的排放量最大,分别为1023.34,89.45mg/(m2·h),金川河两种气体排放量次之,内、外秦淮河CO2排放量相当,而内秦淮CH4的排放量比外秦淮小1个量级.丁解水库该2种温室气体排放量最小.金川河N2O的排放量最高,为151.31μg/(m2·h),团结河N2O排放量次之[111.74μg/(m2·h)],其他2条河流和丁解水库N2O的排放量均在一个量级上(101).水-气界面温室气体的排放受温度、压力、风速等环境因子影响.温室气体的昼夜变化分析结果表明,除了金川河N2O的排放趋势为昼间排放、夜间吸收外,其余河流及丁解水库均为温室气体的排放源.内秦淮和丁解水库的排放趋势受人为因素影响较大,外秦淮河的排放趋势主要受水位的高低变化影响,团结河的排放量受风速和温度的共同影响.金川河主要受微生物活性影响3种温室气体均呈明显的昼夜变化.5种水体在春季是大气3种温室气体的主要排放源.     

硝化抑制剂双氰胺对菜地土壤N_2O排放的影响

采用原状土柱试验研究了施用硝化抑制剂双氰胺（DCD）对菜地（小白菜和辣椒）土壤N2O排放的影响.结果表明,施用DCD能显著降低菜地土壤N2O排放通量和排放总量,小白菜未施用DCD时施氮处理土壤N2 O排放总量为0.22 kg.hm-2,施用DCD后则显著减少至0.11 kg.hm-2,相当于减少了49.33%的土壤N2...     

耕作制度对川中丘陵区冬灌田CH4和N2O排放的影响

采用静态暗箱/气相色谱法连续2 a田间原位测定,研究川中丘陵区冬灌田CH₄和N₂O的排放特征和不同耕作制度对冬灌田CH₄和N₂O排放的影响.结果表明,1a只种1季中稻冬季灌水休闲的冬灌田(PF),在水稻生长期,CH₄平均排放通量为(21.44±1.77)mg·(m²·h)^-1,非水稻生长期为(3.77±0.99)mg·(m²·h)^-1,分别大大低于以前文献报道的在西南其它地方观测值;全年CH₄排放量以水稻生长期CH₄排放量为主,非水稻生长期CH₄排放量仅占全年总排放量的23.2%.冬灌田N₂O排放通量年均值为(0.051±0.008)mg·(m²·h)^-1,且主要集中在水稻生长季,非水稻生长期N₂O排放量仅占全年总排放量的8.1%.在采用水旱轮作制后,冬灌田CH₄排放量大大降低,稻-麦轮作(RW)和稻-油菜轮作(RR)全年CH₄排放量分别为PF的43.8%和40.6%.但冬灌田改为水旱轮作制后,N₂O排放量显著增大,RW和RR的N₂O年排放量分别是PF的3.7倍和4.5倍.综合考虑冬灌田在采用不同耕作制度后排放CH₄和N₂O的全球增温潜势(GWP),无论是短时间尺度还是长时间尺度,采用3种耕作制度全年所排放的CH₄和N₂O所产生的综合GWP都为:PF RW≈RR.在20a、100a和500a时间尺度上,PF分别约是RW和RR的2.6、2.1和1.7倍.冬灌田改为水旱轮作制度后能大大减少CH₄和N₂O所产生的综合GWP.     

生活垃圾填埋场春夏季CH4释放及影响因素

采用静态箱法监测了2个生活垃圾填埋场春、夏季及昼夜的CH₄释放通量,并分析了影响CH₄释放的相关因素. 结果表明:填埋气体(LFG)主动收集对填埋场CH₄释放的影响显著. 在填埋龄相近的条件(4.0～4.5年)下,无LFG主动收集的填埋场春、夏季CH₄的释放通量(以CH₄计)平均值〔(541±1　005) mg/(m2·h)〕比有LFG主动收集的填埋场提高4.4倍. 在有LFG主动收集的填埋场内,填埋龄为1.0～1.5年的非渗滤液灌溉区的CH₄释放通量均值〔(324±847)mg/(m2·h)〕为灌溉区的10.0倍左右. 在有LFG主动收集的填埋场内,CH₄释放通量与各环境因子间无显著相关;而在无LFG主动收集的填埋场内,CH₄释放通量分别与覆土温度和气温呈显著正相关,与大气压强呈显著负相关.相关性分析结果表明,CH₄释放通量与填埋场覆土中含水率,w(有机碳)和w(总氮)呈显著正相关.      

Fluxes of CH4 and N2O from soil under a tropical seasonal rain forest in Xishuangbanna, Southwest China

CH4 and N2O fluxes from soil under a tropical seasonal rain forest in Xishuangbanna, Southwest China were measured for one year using closed static chamber technique and gas chromatography method. Three treatments were set in the studied field: (A) litter-free,(B) with litter, and (C) with litter and seedling. The results showed that the soil in our study was a sink of atmospheric CH4 and source of atmospheric N2O. The observed mean CH4 fluxes from treatments A, B, and C were -50.0±4.0, -35.9±2.8,-31.6±2.8 μgC/(m2·h),respectively,and calculated annual fluxes in2003 were -4.1,-3.1,and -2.9kgC/hm2,respectively.The observed mean N2O fluxes from treatments A,B,and C were 30.9±3.1,28.2±3.5,50.2±3.7μgN/(m2·h),respectively,and calculated annual fluxes in 2003 were 2.8, 2.6, and 3.7 kgN/hm2, respectively. Seasonal variations in CH4 and N2O fluxes were significant among all the three treatments. The presence of litter decreased CH4 uptake during wet season (P ＜ 0.05), but not during dry season. There was a similar increase in seedlings-mediated N2O emissions during wet and dry seasons, indicating that seedlings increased N2O emission in both seasons. A strong positive relationship existed between CH4 fluxes and soil moisture for all the three treatments, and weak relationship between CH4 fluxes and soil temperature for treatment B and treatment C. The N2O fluxes correlated with soil temperature for all the three treatments.     

鼎湖山主要森林生态系统地表N_2O通量

利用静态箱-气相色谱法对鼎湖山3 种处于演替不同阶段的森林类型(季风常绿阔叶林、针阔叶混交林和马尾松林)的地表N2O 通量进行了 1 年的原位观测和研究.结果表明,3 种林型地表 N2O 通量按从大到小的顺序为:季风林>混交林>松林;不同林型间的 N2O 通量差异与森林土壤的性质有密切关系,C/N 比值较低的季风林凋落叶对土壤中产生N2O 的微生物过程有较为明显的促进作用;从全年来看,松林地表N2O 通量的季节变化不明显,而季风林和混交林的地表 N2O 通量在雨季存在明显的降雨驱动效应,统计分析显示在该地区影响森林地表N2O 通量的主要因子是土壤湿度.     

万山汞矿区地表与大气界面间汞交换通量研究

采用动力学通量箱与高时间分辨率大气自动测汞仪联用技术对万山汞矿区不同季节、不同地表与大气界面间汞交换通量和大气汞含量进行了测定.结果显示,受人为活动和地表强烈释汞的影响,万山地区大气汞含量高出背景区1～3个数量级,在冶炼厂附近平均值可达1 101.8 ng/m³,最低平均值达17.8 ng/m³,显示万山汞矿区已遭受较严重的大气汞污染.万山汞矿区土壤与大气界面汞交换非常强烈,土壤向大气的释汞通量最高可达27 827 ng/(m².h),大气汞干沉降通量最高可达9 434ng/(m²·h).万山汞矿区土壤与大气汞交换通量主要受光照强度、大气汞含量影响.光照在土壤释汞过程中起促进作用,而较高的大气汞含量则抑制了土壤向大气的释放,并导致大气汞强烈的干沉降.不同的地表类型对地表释汞影响较大,植被覆盖土壤释汞通量显著低于无植被覆盖地区,而冶炼后的矿渣堆则成为大气汞的净源.     

Methane and nitrous oxide fluxes from four tundra ecotopes in Ny-Ålesund of the High Arctic

During the summers of 2008 and 2009, net methane（CH4） and nitrous oxide（N2O） fluxes were investigated from 4 tundra ecotopes： normal lowland tundra（LT）, bird sanctuary tundra（BT）, the tundra in an abandoned coal mine（CT） and the tundra in scientific bases（ST） in Ny-Alesund of the High Arctic. Tundra soils in CT（184.5 ± 40.0 μg CH4/（m2·hr）） and ST（367.6 ± 92.3 μg CH4/（m2·hr）） showed high CH4 emissions due to the effects of human activities, whereas high CH4 uptake or low emission occurred in the soils of LT and BT.The lowland tundra soils（mean,-4.4-4.3 μg N2O/（m2·hr）） were weak N2 O sources and even sinks. Bird activity increased N2 O emissions from BT with the mean flux of7.9 μg N2O/（m2·hr）. The mean N2 O fluxes from CT（45.4 ± 10.2 μg N2O/（m2·hr）） and ST（78.8 ± 18.5 μg N2O/（m2·hr）） were one order of magnitude higher than those from LT and BT, indicating that human activities significantly increased N2 O emissions from tundra soils. Soil total carbon and water regime were important factors affecting CH4 fluxes from tundra soils. The N2 O fluxes showed a significant positive correlation with ammonia nitrogen（NH4＋-N） contents（r = 0.66, p 〈 0.001） at all the observation sites, indicating that ammonia nitrogen（NH4＋-N） content acted as a strong predictor for N2 O emissions from tundra soils. The CH4 and N2O fluxes did not correspond to the temperature variations of soil at 0-15 cm depths.Overall our results implied that human activities might have greater effects on soil CH4 and N2O emissions than current climate warming in Ny-Alesund, High Arctic.     

放牧对草原十壤N2O产生及微生物的影响

利用AIM乙炔抑制法 ,首次测试了我国内蒙古放牧和非放牧羊草草原土壤N2 O产生的微生物过程 ;通过分析不同类型草原土壤N2 O产生的微生物过程和相关微生物菌群的季节变化 ,研究了放牧行为对于草原土壤N2 O微生物产生过程的影响 .放牧行为改变了土壤结构 ,有利于土壤微生物反硝化作用的发生 ,在一定程度上降低了草原土壤N2 O的排放 .揭示了内蒙古草原土壤N2 O产生是以异养硝化作用过程为主的微生物过程 ,解释了内蒙古典型草原土壤N2 O通量较低和其季节变化的微生物学机理     

Nitrogen cycling of atmosphere-plant-soil system in the typical Calamagrostis angustifolia wetland in the Sanjiang Plain, Northeast China

The nitrogen (N) distribution and cycling of atmosphere-plant-soil system in the typical meadow Calamagrostis angustifolia wetland (TMCW) and marsh meadow Calamagrostis angustifolia wetland (MMCW) in the Sanjiang plain were studied by a compartment model. The results showed that the N wet deposition amount was 0.757 gN/(m2·a), and total inorganic N (TIN) was the main body (0.640 gN/(m2·a)). The ammonia volatilization amounts of TMCW and MMCW soils in growing season were 0.635 and 0.687 gN/m2, and the denitrification gaseous lost amounts were 0.617 and 0.405 gN/m2, respectively. In plant subsystem, the N was mainly stored in root and litter. Soil organic N was the main N storage of the two plant-soil systems and the proportions of it were 93.98% and 92.16%, respectively. The calculation results of N turnovers among compartments of TMCW and MMCW showed that the uptake amounts of root were 23.02 and 28.18 gN/(m2·a) and the values of aboveground were 11.31 and 6.08 gN/(m2·a), the re-translocation amounts from aboveground to root were 5.96 and 2.70 gN/(m2·a), the translocation amounts from aboveground living body to litter were 5.35 and 3.38 gN/(m2·a), the translocation amounts from litter to soil were larger than 1.55 and 3.01 gN/(m2·a), the translocation amounts from root to soil were 14.90 and 13.17 gN/(m2·a), and the soil (0-15cm) N net mineralization amounts were 1.94 and 0.55 gN/(m2·a), respectively. The study of N balance indicated that the two plant-soil systems might be situated in the status of lacking N, and the status might induce the degradation of C. angustifolia wetland.