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1.
城市景观水体是大气CO2与CH4的排放热源,而水生植物作为景观水体的重要组成要素,对水体温室气体排放动态的影响并不清楚。选择重庆市观音塘国家湿地公园为研究区,利用漂浮箱法与顶空平衡法对观音塘水域7种不同水生植物分布区进行水-气界面CO2与CH4排放通量及CO2、CH4溶存浓度进行季节性监测,估算了植物传输对气体通量的贡献。结果表明:1)观音塘水体CO2与CH4浓度范围分别为8.0—341.8μmol/L和0.23—5.26μmol/L,排放通量分别为26.5—869.1 mmol m-2 d-1和0.40—11.15 mmol m-2 d-1,是大气净CO2与CH4排放源;2)观音塘开敞水区CO2与CH4排放通量低于大部分城市湖泊或景观水体...  相似文献   

2.
展鹏飞  仝川 《应用生态学报》2023,(11):2958-2968
湿地生态系统是吸收全球大气二氧化碳(CO2)的汇,同时土壤厌氧环境造成其是大气甲烷(CH4)的源。尽管有证据表明,湿地生态系统CH4排放部分抵消其对大气CO2的净吸收,但目前未见全球尺度湿地CH4排放对其净生态系统CO2交换(NEE)抵消效应的研究。本研究分析了全球内陆湿地(泥炭湿地和非泥炭湿地)以及滨海湿地(海草床、盐沼和红树林)中同时测定湿地NEE和CH4排放通量的数据。结果表明:各类型湿地生态系统均为大气CO2的汇,NEE值排序为红树林(-2011.0 g CO2·m-2·a-1)<盐沼(-1636.6 g CO2·m-2·a-1)<非泥炭地(-870.8 g CO2·m-2·a-1)<泥炭地(...  相似文献   

3.
目前, 有关增温条件下荒漠生物土壤结皮(BSCs)-土壤系统与大气之间主要温室气体(CO2、CH4和N2O)通量变化的研究十分匮乏, 以致很难准确地评估荒漠生态系统温室气体通量对气候变暖的响应与反馈的方向和程度。该文选择腾格里沙漠东南缘天然植被区由藻类、藓类以及二者混生的3种类型的BSCs覆盖土壤为研究对象, 以开顶式生长室(OTC)为增温方式模拟全球变暖, 采用静态箱-气相色谱法探究了2012年7月至2013年6月增温和不增温处理下CO2、CH4和N2O通量的变化特征。结果表明: 增温和结皮类型对CO2、CH4和N2O通量没有显著影响。采样日期、结皮类型与采样日期, 以及增温与结皮类型和采样日期的互作显著影响CO2和CH4通量, 增温和采样日期互作显著影响CH4通量。BSCs-土壤系统的CO2、CH4和N2O年通量及其增温潜能在增温和不增温处理下的差异均不显著。CO2通量与5 cm深度的土壤温度呈显著的指数正相关关系, 与10 cm深度的土壤湿度呈线性正相关关系; 藓类、混生结皮的CH4通量与5 cm深度的土壤温度和10 cm深度的土壤湿度均呈显著的线性负相关关系; 3种结皮类型的N2O通量与5 cm深度的土壤温度均无相关关系, 藓类结皮的N2O通量与10 cm深度的土壤湿度呈显著的线性负相关关系。藓类结皮的CO2和CH4在增温和不增温两种处理下的通量差异与5 cm深度的土壤温度差异呈显著的负线性相关, 藻类结皮N2O的通量差异与温度差异呈近似正相关关系(p = 0.051)。以上结果说明: 在全球变暖的背景下, 荒漠BSCs-土壤系统主要温室气体通量不会有明显的变化, 意味着荒漠生态系统温室气体的排放可能对气候变暖没有明显的 反馈。  相似文献   

4.
薛璟  陈辛安  王宪伟  孙晓新 《生态学报》2024,44(5):1918-1927
北方内陆水体是温室气体排放的热点,对量化区域碳收支起重要作用,但其排放的季节变化尚不清楚。观测了大兴安岭多年冻土区府库奇河及其改道形成的牛轭湖(演替晚期)冻结期冰层中储存的二氧化碳(CO2)和甲烷(CH4)浓度,并比较了两种水体中CO2和CH4浓度在三个不同时期(冻结期、非冻结期、春季融化)的差异。结果表明:两种水体CO2和CH4浓度季节变化存在差异。牛轭湖在冻结期水体中CO2和CH4浓度最高,有明显的冰下积累现象,其中CH4浓度平均值为(2.21±0.54)μmo/L,分别是非冻结期和春季融化期水体CH4浓度的5倍和14倍。河流水体中CO2和CH4浓度最高出现在春季融化期,显著高于非冻结期和冻结期(P<0.05)。水中CO2和CH4浓度受多种环境因子的影响,与可溶性有机碳(D...  相似文献   

5.
沼泽湿地是大气甲烷(CH4)的重要来源, 但有关亚热带亚高山沼泽湿地CH4排放的研究却鲜有报道, 特别是对不同覆被类型泥炭藓沼泽湿地CH4排放量的精确估算及其与环境因子的关系尚不清楚。该研究选择鄂西南亚高山泥炭藓沼泽湿地为研究区域, 于2018年11月-2019年10月间, 使用静态箱-气相色谱仪法原位测定3种覆被类型泥炭藓沼泽湿地CH4通量, 同步记录大气和地下5 cm土壤的温度以及地下水位变化。结果表明: (1)光照下, 裸露地(B)、泥炭藓(Sphagnum paluster)(S)、金发藓(Polytrichum commune)(P) 3种覆被类型泥炭藓沼泽湿地CH4-C通量全年变化范围分别为: 0.012-1.372、0.022-1.474、0.027-3.385 mg·m-2·h-1; 遮光处理下, B、S、P 3种覆被类型泥炭藓沼泽湿地CH4-C通量的全年变化范围分别为: 0.012-1.372、0.009-1.839、0.017-2.484 mg·m-2·h-1, 均为CH4排放源。同时, 光照条件下不同覆被泥炭藓沼泽湿地CH4排放量略大于黑暗条件, 但差异不明显。(2)不同覆被类型泥炭藓沼泽湿地CH4排放存在明显的季节变化规律, 即: 夏季>秋季>春季>冬季, 其中夏季CH4排放量显著大于其他季节, 占全年的57%-84%。该研究发现泥炭藓沼泽湿地CH4通量均与气温和地下5 cm土壤温度极显著相关, 且CH4排放量随温度升高呈指数增加, 表明温度是影响泥炭藓沼泽湿地CH4排放时间变化的主要环境因子。(3) 3种覆被类型泥炭藓沼泽湿地的年平均和年累计CH4排放量均依次为: P > S > B, P显著大于B。该研究发现植被类型与泥炭藓沼泽湿地CH4排放量存在显著相关性, 表明覆被类型是影响泥炭藓沼泽湿地CH4排放量空间变异的主要因子。(4) 3种覆被类型泥炭藓沼泽湿地CH4排放量均与地下水位变化不相关。该研究进一步丰富了泥炭藓沼泽湿地CH4排放规律, 同时也为区域碳循环提供了详实的基础数据。  相似文献   

6.
三江平原小叶章湿地碳排放对雪被变化的短期响应   总被引:1,自引:0,他引:1  
为了解三江平原小叶章湿地碳排放对雪被变化的响应,利用黑龙江省科学院自然与生态研究所三江平原湿地生态定位研究站内试验平台,采用静态箱-气相色谱法,分别对剔除雪被处理(0 cm)和添加雪被处理(50 cm)以及对照(20 cm)小叶章湿地进行了温室气体排放通量观测,并同步观测相关环境因子。结果表明:不同处理土壤温度、含水量及碳排放量均在覆雪期较低,并随时间呈逐渐升高趋势。随着时间推移和雪被厚度增加,土壤温度不断上升,处理间差异逐渐缩小;剔除雪被处理的土壤含水量始终低于对照和添加雪被处理;在融雪期和后融雪期,对照和添加雪被处理比剔除雪被处理更能促进土壤CO2排放;各时期土壤累积CH4排放量在不同处理间无显著性差异。土壤温度与累积CO2和CH4排放量均呈显著相关关系,随土壤温度的升高,土壤累积CO2排放量持续增加,土壤累积CH4排放量呈先减少后迅速增加趋势;土壤含水量与累积CO2和CH4排放量也呈显著相关关系,随土壤含水量的增加,土壤累积CO2排放量逐渐增多,达到一定值后趋于平缓,土壤累积CH4排放量则持续显著增加。  相似文献   

7.
若尔盖高原是我国泥炭沼泽湿地的主要分布区、青藏高原的主要甲烷(CH4)排放中心。为了研究湿地微地貌环境对高原湿地CH4排放通量的影响, 2014年5-10月, 采用静态箱和快速温室气体分析仪原位测量若尔盖高原湖滨湿地3种泥炭沼泽5种微地貌环境下的CH4排放通量特征。结果表明: (1)常年性淹水泥炭湿地洼地(P-hollow)和草丘(P-hummock)生长季平均CH4排放通量为68.48和40.32 mg·m-2·h-1, 季节性淹水的泥炭湿地洼地(S-hollow)和草丘(S-hummock)平均CH4排放通量为2.38和0.63 mg·m-2·h-1, 而无淹水平坦地(Lawn)平均CH4排放通量为3.68 mg·m-2·h-1; (2)湿地5种微地貌区CH4排放通量为(23.10 ± 30.28) mg·m-2·h-1 (平均值±标准偏差)), 变异系数为131%。分析显示这5种微地貌区CH4排放通量的平均值与其水位深度平均值存在显著的线性正相关关系(R2 = 0.919, p < 0.01), 表明水位深度是控制湿地微地貌区CH4排放通量空间变化的主要因子; (3) P-hummock、P-hollow和S-hummock的CH4排放通量存在显著的季节变化, Lawn和S-hollow无明显的季节性变化, 但5种微地貌区在夏季或秋季均观测到CH4排放通量峰值, 其影响因子可能与水位深度、土壤温度和凋落物输入密切相关; (4) P-hollow可能时常发生冒泡式CH4排放, 这可能导致过去低估了若尔盖高原湿地的CH4排放量。  相似文献   

8.
大兴安岭永久冻土区7种沼泽类型土壤温室气体排放特征   总被引:1,自引:0,他引:1  
气候变暖及永久冻土退化将会增加冻土湿地的温室气体排放,但关于大兴安岭永久冻土区沼泽湿地温室气体通量及主控因子尚不明确。采用静态箱-气相色谱法,同步原位观测大兴安岭永久冻土区7种天然沼泽类型(草丛沼泽-C、灌丛沼泽-G、毛赤杨沼泽-M、白桦沼泽-B、落叶松苔草沼泽-LT、落叶松藓类沼泽-LX、落叶松泥炭藓沼泽-LN)土壤CO2、CH4和N2O通量及土壤温度、水位、化冻深度及土壤碳氮含量、碳氮比、pH值及含水量,揭示永久冻土区沼泽土壤温室气体通量及其主控因子。结果表明:1) 7种沼泽类型土壤CO2年均通量(125.12—163.33 mg m-2 h-1)相近;2) CH4年均通量(-0.007—0.400 mg m-2 h-1)呈草丛显著高于其他沼泽5.6—65.7倍(P<0.01);3) N2O年均通量(1.52—37.90μg m-2 h<...  相似文献   

9.
采用静态箱-气相色谱法,对科尔沁半干旱地区典型的沙丘-草甸梯级生态系统中半流动沙丘和草甸湿地的温室气体(CO2、CH4、N2O)通量进行了观测,分析了生长季温室气体的动态变化及其与环境影响因子的关系.结果表明: 生长季半流动沙丘和草甸湿地CH4通量均整体表现为吸收,平均值分别为-52.7和-34.7 μg·m-2·h-1,介于-176.1~49.8 μg·m-2·h-1之间变化,8月22日半流动沙丘CH4吸收值达到生长季最大值;8、9月降雨集中时段内草甸湿地CH4通量表现为持续排放,与半流动沙丘呈明显差异.N2O通量在7月21日达到生长季最大值,半流动沙丘N2O通量的月均值表现为7月>8月>9月>6月>5月.土壤温湿度是影响CO2和CH4通量的关键因子,N2O通量主要受土壤温度的影响.样地土壤温度敏感性(Q10)表现为半流动沙丘(1.009)<草甸湿地(1.474),半流动沙丘土壤受到水分胁迫,导致其温室气体通量对土壤温度变化的敏感性明显低于草甸湿地.  相似文献   

10.
滨海盐沼湿地是重要的“蓝碳”碳汇,研究水盐变化对土壤碳矿化(CO2和CH4排放)的影响,对理解滨海盐沼湿地的碳汇稳定机制具有重要意义。该研究选取黄河三角洲典型盐沼湿地土壤为研究对象,通过水盐梯度模拟实验,研究土壤碳矿化、理化性质、微生物生物量及群落结构对不同土壤水分和盐分含量的响应。主要结果:(1)水盐变化对土壤CO2、CH4排放量以及CH4:CO2的影响均不存在交互作用,CO2排放量随土壤含水量增加呈先升后降的单峰型变化趋势,盐分含量升高则显著抑制CO2排放;水分含量升高对CH4排放具有显著促进作用,盐分升高则显著抑制CH4排放。(2)水盐变化对土壤可溶性有机碳(DOC)含量具有弱交互作用,在低水分处理下,DOC随着土壤盐分的增加呈减少趋势,但在高水分处理下呈增加趋势;CO2排放与DOC含量呈显著正相关关系,而CH4排放与D...  相似文献   

11.
Adding one equivalent of H2O2 to compounds of stoichiometry MoCl2(O)2(OPR3)2, OPR3 = OPMePh2 or OPPh3, leads to the formation of oxo-peroxo compounds MoCl2(O)(O2)(OPR3)2. The compound MoCl2(O)(O2)(OPMePh2)2 crystallized with an unequal disorder, 63%:37%, between the oxo and peroxo ligands, as verified by single-crystal X-ray diffractometry, and can be isolated in reasonable yields. MoCl2(O)(O2)(OPPh3)2, was not isolated in pure form, co-crystallized with MoCl2(O)2(OPPh3)2 in two ratios, 18%:82% and 12%:88%, respectively, and did not contain any disorder in the arrangement of the oxo and peroxo groups. These complexes accomplish the isomerization of various allylic alcohols. A mechanism of this reaction has been constructed based on 18O isotopic studies and involves exchange between the alcohol and metal bonded O atoms.  相似文献   

12.
Two new zincophosphites [C6H14N2]0.5[Zn(H2PO3)2] 1 and [C4H12N2]0.5[(CH3)2NH2][Zn2(HPO3)3] 2 have been solvothermally synthesized in mixed solvents of N,N-dimethylformamide (DMF) and 1,4-dioxane (DOA), respectively. Single-crystal X-ray diffraction analysis reveals that compound 1 exhibits a neutral inorganic chain formed by ZnO4 and HPO2(OH) units. Interestingly, the left- and right-handed hydrogen-bonded helical chains are alternately formed via the hydrogen-bonds between two adjacent chains. Compound 2 exhibits a layer structure with 4- and 12-MRs formed by ZnO4 and HPO3 units, in which two kinds of organic amine molecules both act as countercations to compensate the overall negative electrostatic charge of the anionic network.  相似文献   

13.
Reaction of tetrathiafulvalene carboxylic acid (TTFCO2H) with paddlewheel dirhodium complex Rh2(ButCO2)4 yielded TTFCO2-bridged complexes Rh2(ButCO2)3(TTFCO2) (1) and cis- and trans-Rh2(ButCO2)2(TTFCO2)2 (cis- and trans-2). Their triethylamine adducts [1(NEt3)2] and cis-[2(NEt3)2] were purified and isolated with chromatographic separation, and characterized with single crystal X-ray analysis. Trans-[2(NEt3)2] is not completely separated from a mixture of cis- and trans-[2(NEt3)2], but its single crystals were obtained from a solution of the mixture. A three-step quasi-reversible oxidation process was observed for 1 in MeCN. The first two steps correspond to the oxidation of the TTFCO2 moiety and the last one is the oxidation of the Rh2 core. The oxidation of cis-2 is observed as a two-step process with very similar E1/2 values to those of the first two processes for 1. Both 1+ and cis-22+ in MeCN at room temperature show isotropic ESR spectra with a g value of 2.008 and aH = 0.135 mT for two equivalent H atoms and aH = 0.068 mT for one H atom. The redox and ESR data of cis-2 suggest that the intramolecular interaction between the TTF moieties is very small.  相似文献   

14.
Refluxing WCl4(PMe3)3 under a nitrogen atmosphere in the presence of two equivalents of sodium amalgam leads to a reduction to the W(II) complex [cis,mer-WCl2(PMe3)3]2N2 (1), which can be converted to [mer,trans-WCl3(PMe3)2]2N2 (2) via appropriate oxidation/chlorination. Structural data have been obtained for both complexes, and demonstrate significantly increased steric crowding in 1 due to PMe3/PMe3 interactions. The N-N bond distances in the two compounds are similar, at 1.279(4) and 1.243(18) Å, respectively.  相似文献   

15.
The title compounds were made by reacting bis(diphenylphosphino)methane (dppm) with reduced solutions of OsCl64? and Ru2OCl104?. The crystal and molecular structures of these compounds have been determined form three-dimensional X-ray study. The cis-isomers crystallize with one CHCl3 per molecule of the complex. All three compounds crystallize in the monoclinic space group P21/n with unit cell dimensions as follows: Cis-OsCl2(dppm)2·CHCl3: a = 13.415(4) Å, b = 22.859(4) Å, c = 16.693(3) Å, β = 105.77(3)°, V = 4926(3) Å3, Z = 4. cis-RuCl2(dppm)2·CHCl3: a = 13.442(3) Å, b = 22.833(7) Å, c = 16.750(4) Å, β = 105.53(2)°, V = 4953(3) Å3, Z = 4. trans-RuCl2(dppm)2: a = 11.368(7) Å, b = 10.656(6) Å, c = 18.832(12) Å; β = 103.90(6)°, V = 2213(7) Å3; Z = 2. The structures were refined to R = 0.044 (Rw = 0.055) for cis-OsCl2(dppm)2·CHCl3; R = 0.065 (Rw = 0.079) for cis-RuCl2(dppm)2·CHCl3 and R = 0.028 (Rw = 0.038) for trans-RuCl2(dppm)2. The complexes are six coordinate with stable four-membered chelate rings. The PMP angle in the chelate rings is ca. 71° in each case.  相似文献   

16.
Recent updates on Magnetic Nano-Particles (MNPs) based separation of nucleic acids have received more attention due to their easy manipulation, simplicity, ease of automation and cost-effectiveness. It has been indicated that DNA molecules absorb on solid surfaces via hydrogen-bonding, and hydrophobic and electrostatic interactions. These properties highly depend on the surface condition of the solid support. Therefore, surface modification of MNPs may enhance their functionality and specification. In the present study, we functionalized Fe3O4 nano-particle surface utilizing SiO2 and TiO2 layer as Fe3O4/SiO2 and Fe3O4/SiO2/TiO2 and then compare their functionality in the adsorption of plasmid DNA molecules with the naked Fe3O4 nano-particles. The result obtained showed that the purity and amount of DNA extracted by Fe3O4 coated by SiO2 or SiO2/TiO2 were higher than the naked Fe3O4 nano-particles. Furthermore, we obtained pH 8 and 1.5 M NaCl as an optimal condition for desorption of DNA from MNPs. The result further showed that, 0.2 mg nano-particle and 10 min at 55 °C are the optimal conditions for DNA desorption from nano-particles. In conclusion, we recommended Fe3O4/SiO2/TiO2 as a new MNP for separation of DNA molecules from biological sources.  相似文献   

17.
The photophysical properties (absorption, emission, and excitation spectra; luminescence quantum yields; luminescence decay lifetimes ) of K13[Eu(SiW11O39)2] and K15[Eu(BW11O39)2] in aqueous solution and in the solid state are reported. Both complexes exhibit broad and very intense O → W charge transfer bands in the U.V. region and weak and narrow f → f Eu3+ bands in the visible. At 77 K the luminescence emission of both complexes, which consists of 5DO7FJ bands split by the local crystal field, can be pumped very efficiently via both the O → W CT and the f → f Eu3+ levels, whereas at 298 K only pumping via the f → f Eu3+ is efficient. The values of the luminescence decay lifetimes in H2O and D2O solution are quite similar, showing that no water molecule is coordinated to the central Eu3+ ion. The high resolution emission spectra are discussed in an attempt to define the coordination symmetry of Eu3+.  相似文献   

18.
The hydrothermal reaction of cobalt(II)oxalate di-hydrate, zinc oxide, and triethyl-orthophosphate, using 1,2-diaminoethane as structure directing template in water, produced two major crystal phases in almost equal amount: the purple crystals of [NH3-CH2CH2NH3][Co0.7Zn1.3(PO4)2] (1) and the red burgundy crystals of Co6.2(OH)4(PO4)4Zn1.80 (2), a new adamite type phase. The structure of [NH3-CH2CH2NH3] [Co0.7Zn1.3(PO4)2] (1) exhibits a 3D open framework built from PO4 and (Co/Zn)O4 tetrahedra, and (Co/Zn)O5 trigonal bipyramids, forming two major channels, an 8-membered ring channel and a 16-membered ring channel, that host the ethanediammonium ions. The Co6.2(OH)4(PO4)4Zn1.80 (2) is isomorphous with adamite-type M2(OH)XO4 structure, with a condensed vertex and edge sharing network of (Co/Zn)O5, and distorted CoO6, and PO4 subunits. The cobalt preference for higher coordination numbers is displayed in this structure, where the octahedral sites are wholly occupied by cobalt. Thermal analysis confirmed that these compounds display high thermal stability.  相似文献   

19.
It was found that the lanthanide diiodides LnI2 (1) (Ln = Nd, Sm, Eu, Dy, Tm, Yb) are dissolved in isopropylamine (IPA) without redox transformations. Stability of the formed solutions decreases in a row Eu ≈ Yb > Sm > Tm > Dy > Nd. Removing of a solvent in vacuum leaves complexes LnI2(IPA)x (2) (Nd, x = 5; Sm, Eu, Dy, Tm, Yb, x = 4) as crystalline colored solids. Stability of 2-Nd,Dy,Tm is higher than that of known THF or DME coordinated salts. Divalent state of metal in the products is confirmed by data of UV-Vis spectroscopy, magnetic measurements and their chemical behavior. Structure of 2-Eu and 2-Tm was established by X-ray diffraction analysis. Oxidation of 2-Nd,Dy in IPA affords amine-amides (PriNH)Ln(IPA)y (3) (Nd, y = 4; Dy, x = 3). n-Propylamine also dissolves the iodides 1-Sm,Eu,Dy,Tm,Yb but stability of the solutions is significantly lower. 1-Nd vigorously reacts with PrnNH2 even at −30 °C which hampers the formation of the solution.  相似文献   

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