Stable isotopes in aquatic food web of an artificial lagoon in the Hangzhou Bay,China

Stable isotope values, δ13C and δ15N, were determined for four primary producers and 19 dominant consumers in a small artificial lagoon located in Hangzhou Bay. Based on these results the major pathways for energy flow and trophic structure of the artificial lagoon ecosystem were characterized. The mean δ13C values for the 19 consumers ranged from -22.99‰ to -14.24‰. Apart from so-iny mullet Liza haematocheila, the other 18 consumers had intermediate δ13C values between those of epibenthic microalgae and particulate organic matter (POM). The results of a multiple source linear mixing model (IsoSource model) indicated that 50% or more of the organic carbon in the tissues of most consumers was derived from epibenthic microalgae. This indicated that these primary producers were the main food source fueling the lagoon food web. The mean δ15N values for the 19 consumers varied between 4.93‰ and 12.97‰ and indicated four trophic levels in the lagoon. Four macroinvertebrates and zooplankton represented the primary consumers, whilst the other 14 consumers occupied the secondary and tertiary consumer levels. The 19 consumers were divided into three trophic guilds (detritivores/suspension feeders, omnivores and carnivores).

Dynamics of soil organic carbon following land-use change:insights from stable C-isotope analysis in black soil of Northeast China

Intensive soil tillage is a significant factor in soil organic matter decline in cultivated soils. Both cultivation abandonment and foregoing tillage have been encouraged in the past 30 years to reduce greenhouse gas emissions and soil erosion. However, the dynamic processes of soil organic carbon (SOC) in areas of either continuous cultivation or abandonment remain unclear and inconsistent.Our aims were to assess and model the dynamic processes of SOC under continuous tillage and after cultivation abandonment in the black soil of Northeast China. Soil profiles were collected of cultivated or abandoned land with cultivation history of 0–100 years. An isotope mass balance equation was used to calculate the proportion of SOC derived from corn debris (C_4) and from natural vegetation (C_3) to deduce the dynamic process. Approximately 40% of SOC in the natural surface soil (0–10 cm) was eroded in the first 5 years of cultivation, increasing to about 75% within 40 years, before a slow recovery. C_4 above 30 cm soil depth increased by 4.5%–5% or 0.11–0.12 g·kg^(-1) on average per year under continuous cultivation, while it decreased by approximately 0.34% annually in the surface soil after cultivation abandonment.The increase in the percentage of C_4 was fitted to a linear equation with given intercepts in the upper 30 cm of soil in cultivated land. A significant relationship between the change of C_4 and time was found only in the surface soil after abandonment of cultivation. These results demonstrate the loss and accumulation of corn-derived SOC in surface black soil of Northeast China under continuous tillage or cultivation abandonment.

Determination of trophic levels of marine fish in the Yellow Sea and northern East China Sea using nitrogen stable isotope (δ^(15)N) analysis of otoliths

Fish otolithδ^(15) N(δ^(15) N_(oto))is a demonstrated source of information of dietary history for marine fi sh as it is available iN_(oto)lith archives and sedimentary deposits unlike white muscle tissue(WMT).WMT and stomach content data are insufficient for trophic level(TL)data of past fi shes which is important for the changes of marine fi shery resources over long time scales.To determine the correlation betweenδ^(15) N_(oto) and fi sh WMTδ^(15) N(δ^(15) N_(wmt))and the feasibility of usingδ^(15) N_(oto) in characterizing the TLs of marine fi shes,we conducted nitrogen stable isotope analysis(SIA)in the otolith and WMT of 36 marine fi sh species sampled from the Yellow Sea and northern East China Sea in 2011-2014.Bothδ^(15) N_(oto) andδ^(15) N_(wmt) were analyzed using an elemental analyzer coupled with an isotope ratio mass spectrometer(EA-IRMS).Multiple otoliths were combined to make each otolith measurement and were analyzed as-is without a carbonate dissolution pre-processing step.δ^(15) N_(oto) andδ^(15) N_(wmt) comparisons for species in the Yellow Sea and northern East China Sea are currently lacking and would be helpful for both regional studies and for increasing the number of species for whichδ^(15) N_(oto) andδ^(15) N_(wmt) have been compared.Additionally,to determine the relative accuracy of trophic level calculated usingδ^(15) N_(oto),we compared TL calculated fromδ^(15) N_(oto) to traditional trophic level metrics calculated usingδ^(15) N_(wmt).The results showed a positive and highly signifi cant correlation(R=0.780,P<0.001)betweenδ^(15) N_(oto) andδ^(15) N_(wmt).Trophic level estimation using WMT(TL wmt)and otolith(TL oto)showed congruence in our study,which is not entirely surprising given thatδ^(15) N_(oto) was regressed againstδ^(15) N_(wmt) and the resulting regression coefficient was used to convertδ^(15) N_(oto) toδ^(15) N_(wmt) prior to calculating TL oto.This conversion was required in order to be consistent with previousδ^(15) N_(wmt)-based calculations of TL for comparison.TL oto calculations resulted in TL values that were largely within 5%-10%of TL values calculated withδ^(15) N_(wmt).Our fi ndings show thatδ^(15) N_(oto) is a feasible technique for characterizing the TLs of marine fi sh and can also assist in food web and marine ecosystem studies.

Application of ^15N Stable Isotope Labeling Technology in Sugarcane Nitrogen Research

Nitrogen is one of the essential nutrient elements for plant growth,which plays an important role in the growth and development of sugarcane. The whole growth cycle of sugarcane needs a large amount of nitrogen. Increasing the application of nitrogen can improve the yield of sugarcane,but it will also cause environmental pollution. Therefore,how to control or reduce the application of nitrogen fertilizer while continuously increasing sugarcane yield,reduce the increase of sugarcane production cost and environmental pollution caused by excessive application of nitrogen fertilizer has become an important scientific problem faced by sugarcane industry in China.^15N stable isotope labeling technology has been applied to many crops as a nitrogen research tool. In order to better understand the demand of nitrogen fertilizer in soil-cane system,this paper reviewed nitrogen allocation in plants,nitrogen loss,nitrogen recycling and endogenous nitrogen fixation of sugarcane based on^15N stable isotope labeling technology used in the nitrogen uptake and utilization,providing a theoretical basis for the improvement of sugarcane nitrogen use efficiency and the efficient nitrogen fertilizer management of sugarcane.

Trace element geochemistry and stable isotopic(δ^(13)C andδ^(15)N)records of the Paleocene coals,Salt Range,Punjab,Pakistan

The Paleocene coals of the Salt Range in the Punjab Province of Pakistan have great economic potential;however,their trace element and stable isotopic characteristics have not been studied in detail except for a few sporadic samples.In this study,a total of 59 coal samples of which 14 are obtained from open cast mines have been investigated for elemental composition andδ^(13)C-δ^(15)N isotopic signatures.Average contents of trace elements such as Co,Cr,Cu,Pb,Sr,Th,U,V,and Zn are 7.4,41.7,11.2,12.5,90.2,4.0,1.9,128,and 31.1 mg/kg,respectively.These values,when compared with the World Coal Clarke values,were relatively higher in low-rank coals in comparison with Clarke values for brown coals.Likewise,As(20.4 mg/kg),Co(6.6 mg/kg),Cr(22.4 mg/kg),Cu(^(13).3 mg/kg),Pb(19.2 mg/kg),Sr(^(15)4.7 mg/kg),Th(2.5 mg/kg),V(47.8 mg/kg),and Zn(75.1 mg/kg)were significantly higher in the sub-bituminous to bituminous coals of the Salt Range.Mineralogical analysis,based on X-ray diffraction and energy dispersive X-ray spectroscopy,revealed that the studied samples contain illite,kaolinite calcite,gypsum,pyrite,and quartz.Elemental affinity with organic and inorganic phases of coals calculated by an indirect statistical approach indicated a positive association of ash content with Ag,Al,Co,Cr,Cs,Cu,Mn,P,Rb,Pb,Th,U,and V,suggesting the presence of inorganic components in studied coals.However,As,Fe,Sr,and Zn exhibit negative correlations that imply their association with the organic fraction.Theδ^(13)C andδ^(15)N isotopic range and average−24.94‰to−25.86‰(−25.41‰)and−2.77‰to 3.22‰(0.96‰),respectively,reflecting 3C type modern terrestrial vegetation were common in the palaeomires of studied coal seams.In addition,the trivial variations of 0.92‰and 0.45‰among^(13)C and^(15)N values can be attributed to water level fluctuations and plant assemblies.

Variations in Stable Carbon Isotopic Composition of n-Alkanes from Ordovician- and Triassic-Derived Oils in Lunnan Oilfield, Tarim Basin, NW China: Global Paleoenvironmental Constraints

Molecular stable carbon isotope technique was employed to study well-sourced crude oils collected from a single drilling well and from the entire Lunnan oilfield, Tarim Basin, NW China. The stable carbon isotopic composition of n-alkanes from crude oils showed that Ordovician-derived oils are enriched in {}+{13}C and Triassic-derived oils are depleted in {}+{13}C. This is consistent with the distribution and evolution trend of stable carbon isotope ratios in crude oils/organic matter from all over the world in geological history (Stahl, 1977; Andrusevich et al., 1998). An extensive survey of literature indicates that, except for thermal maturity, organic matter input and depositional environment, paleoenvironmental background is another key factor that affects the stable carbon isotopic composition of Ordovician- and Triassic-derived crude oils. The results showed that gas chromatographic-isotope ratio mass spectrometry (GC-C-IRMS), combining with biogeochemical evolution of organic matter in geological history, may be a powerful tool in refining oil/oil, oil/source correlations in multi-age, multi-source petroliferous basins like Tarim.

C-H-O Stable Isotope, Elements and Fluid Geochemistry of Uraniferous Leucogranites in Gaudeanmus Area, Southern Central Zone, Damara Orogen, Namibia

This paper focuses on the effect of the later hydrotherm on uraniferous leucogranites and the stages of uranium mineralization. Here, we review C-H-O stable isotope, elements and fluid geochemistry of uraniferous leucogranites in Gaudeanmus, Namibia. The results show that there is significant increasing amount of rare earth element from non-mineralized to uraniferous leucogra-nites, indicating the synchronization of REE enrichment and uranium mineralization. Uranium enrichment may have close relations with Pb, Th, Co, Ni, REE in this region, so REE and U evidently exist homology. There are at least two stages of uranium mineralization by later hydrothermal alteration: firstly, due to magnatic residual high temperature and low salinity fluid, the temperature of main metallogenetic epoch ranges from 470°C to 530°C, salinity ranges from 3.55% to 9.60% NaCleq, and C, H, O stable isotope is -23‰ - -13.6‰, -53.3‰ - -46.4‰, 7.71‰ - 8.81‰, respectively. Secondly, due to superim-posed hydrothermal fluid, the temperature, salinity, and C, H, O stable isotope is 150°C - 220°C, 4.65% - 19.05% NaCleq, -20.3‰ -?-3.7‰, -64.7‰ - -53.6‰, 1.49‰ - 1.99‰, respectively. The fluid for reformation is derived from postmagmatic fluid, mixed with a number of meteoric water.

Study the Changes in Soil Organic Carbon of Rice-Maize Cropping System in the Top Layer of Alluvisol Soil in Dan Phuong: A Study of C-13 Stable Isotope Composition (<i>&delta;</i>¹³C)

In this study, the experiments on field were conducted to examine the change in the content of soil organic carbon (SOC), its C-13 stable isotope composition (δ 13C) and some main physical, chemical parameters (soil moisture, pH, soil density, content of humic, fulvic, total N, total P, total K) in alluvial soil of Dan Phuong region—Vietnam at a depth of 0 - 30 cm when we changed the regime from 2 maize -1 rice crop to 2 rice - 1 maize crop per 1 year. In addition to analyzing the main parameters in soil, C content and its δ 13C value in parts of rice and maize (root, stem and leaf) were also analyzed to assess the contribution of plant residues on soil organic carbon content after harvest. The experiment was carried out in 2016-2017 on the field with the traditional farming method of local farmers along with the tropical monsoon weather conditions of the North-Vietnam. The results showed that SOC had positive correlation with total N, total P parameters and negative correlation with δ 13C values of soil samples at two layers (0 - 15 cm and 15 - 30 cm). The average of total dry biomass (stem, stump + roots and leaf parts) per 1 rice and 1 maize crop was 10.64 Mg/ha and 9.09 Mg/ha, respectively. The average of δ 13C value of rice (C3 plant) was -29.78‰ and its value of maize (C4 plant) was -12.61‰. The new plant (rice) contributes to the total soil organic carbon content from 11.31% to 44.14% at the 0 - 15 cm layer and from 6.55% to 11.31% at the 15 - 30 cm layer in one-year experiment period.

Construction of Food Web Model for Liusha Bay-Based on Stable Isotope Analysis

To investigate the food web structure of Liusha Bay,the δ13C and δ15N values of various organisms collected in Liusha Bay were measured via stable isotope technique.Based on the calculated δ15N value,the correlation between stable isotope ratio and trophic level were established to predict the trophic levels of shrimps,crabs,cephalopods and fishes.By comparing the analysis results of stomach contents of 24 organisms,two methods gave a similar consistence in approximately 71% of organisms within a 0.5 trophic level.It is concluded that stable isotope technique could be an effective method for studying ocean food web trophic level.

Differential response of radial growth and δ^(13)C in Qinghai spruce(Picea crassifolia) to climate change on the southern and northern slopes of the Qilian Mountains in Northwest China

Tree radial growth can have significantly differ-ent responses to climate change depending on the environ-ment.To elucidate the effects of climate on radial growth and stable carbon isotope(δ^(13)C)fractionation of Qing-hai spruce(Picea crassifolia),a widely distributed native conifer in northwestern China in different environments,we developed chronologies for tree-ring widths and δ^(13)C in trees on the southern and northern slopes of the Qilian Mountains,and analysed the relationship between these tree-ring variables and major climatic factors.Tree-ring widths were strongly influenced by climatic factors early in the growing season,and the radial growth in trees on the northern slopes was more sensitive to climate than in trees on the southern.Tree-ring δ^(13)C was more sensitive to climate than radial growth.δ^(13)C fractionation was mainly influenced by summer temperature and precipitation early in the growing season.Stomatal conductance more strongly limited stable carbon isotope fractionation in tree rings than photosynthetic rate did.The response between tree rings and climate in mountains gradually weakened as climate warmed.Changes in radial growth and stable carbon isotope fractionation of P.crassifolia in response to climate in the Qilian Mountains may be further complicated by continued climate change.

冠心宁片联合阿托伐他汀对老年稳定型冠心病患者临床疗效、NT-proBNP及hs-CRP水平的影响

目的 探讨老年稳定型冠心病(SCHD)患者采用冠心宁片联合阿托伐他汀治疗对临床疗效、氨基末端B型利钠肽前体(NT-proBNP)及超敏C反应蛋白(hs-CRP)水平的影响。方法 96例老年SCHD患者,以随机数字表法分成研究组与对照组,每组48例。对照组给予阿托伐他汀治疗,研究组给予冠心宁片联合阿托伐他汀治疗。比较两组患者临床疗效以及治疗前后的心功能[左心室收缩末期内径(LVESD)、左心室舒张末期内径(LVEDD)、左心室射血分数(LVEF)]、NT-proBNP、hs-CRP水平。结果 研究组治疗总有效率(95.83%)较对照组(81.25%)更高(P<0.05)。治疗后,两组患者LVEF均提高,LVESD、LVEDD均降低,且与对照组的(38.21±4.35)mm、(49.96±5.24)mm、(62.38±5.91)%相比,研究组LVESD(34.97±4.78)mm、LVEDD(45.71±6.32)mm更低, LVEF(67.12±4.76)%更高(P<0.05)。治疗后,两组患者NT-proBNP、hs-CRP水平均降低,且与对照组的(340.26±18.49)pg/ml、(9.31±1.75)mg/L相比,研究组的NT-proBNP(297.13±15.78)pg/ml、hs-CRP(5.84±1.10)mg/L更低(P<0.05)。结论 冠心宁片联合阿托伐他汀治疗老年SCHD患者,能够提高临床疗效,改善NT-proBNP、hs-CRP水平,促进心功能恢复。

Evaluation on nitrogen isotopes analysis in high-C/N-ratio plants using elemental analyzer/isotope ratio mass spectrometry

Elemental analyzer/isotope ratio mass spectrometry(EA/TRMS) has been widely applied to analyze the^(15)N/^(14)N isotope composition(δ^(15)N) of plants and soils,but the δ^(15)N results may be inaccurate due to incomplete combustion of the high-C/N-ratio plant samples by EA.Therefore,it is necessary to develop a method to solve the problem of imperfect combustion.In this study,we used two methods:1) adding copper oxide powder to the samples,and 2) increasing the O_2 flow(from 100 mL min^(-1) to 200 mL min^(-1)) for the auto sampler inlet purge line of the EA.The δ^(15)N values of the plant samples became more positive and tended to be stable after complete combustion.Also,the required blank samples for each plant sample decreased with increasing amount of the added CuO powder.However,at 200 mL min^(-1) of the oxygen flow in the EA,complete combustion could not be achieved without adding copper oxide,but this was done with decreased amount of CuO powder.Therefore,mixing cupric oxide into the high-C/N-ratio samples was an efficient,simple and convenient way to solve the problem of imperfect combustion in the EA.

Carbon and Hydrogen Isotopes as Tracers of Methane Dynamic in Wetlands

This work presents a review of the main processes leading to the production and sinking of methane in wetlands and how they affect the stable isotope composition of carbon and hydrogen. Isotope fractionation factors associated to diffusion, ebullition, bacterial oxidation, etc., have been gathered from relevant literature in an intent of providing researchers in this thematic with practical procedures and tools for the interpretation of experimental data. Also it is presented guidelines of the most reliable field and laboratory methods used at present for the correct sampling and analyzing methane in different stages of occurrence, as well the most common tools used in their interpretation. Each statement is fully referenced to a long updated list of publications.

Isotopes (¹³C and ¹⁸O) Geochemistry of Lower Triassic Montney Formation, Northeastern British Columbia, Western Canada

Oxygen isotope (δ18O) serves as paleothermometer, and provides paleotemperature for carbonates. δ18O signature was used to estimate the temperature of fractionation of dolomite and calcite in Montney Formation, empirically calculated to have precipitated, between approximately 13°C to ±33°C during Triassic time in northeastern British Columbia, Western Canada Sedimentary Basin (WCSB). Measurements of stable isotopes (δ13C and δ18O) fractionation, supported by quantitative X-ray diffraction evidence, and whole-rock geochemical characterization of the Triassic Montney Formation indicates the presence of calcite, dolomite, magnesium, carbon and other elements. Results from isotopic signature obtained from bulk calcite and bulk dolomite from this study indicates depleted δ13CPDB (-2.18‰ to -8.46‰) and depleted δ18OPDB (-3.54‰ to -16.15‰), which is interpreted in relation to oxidation of organic matter during diagenesis. Diagenetic modification of dolomitized very fine-grained, silty-sandstone of the Montney Formation may have occurred in stages of progressive oxidation and reduction reactions involving chemical elements such as Fe, which manifest in mineral form as pyrite, particularly, during early burial diagenesis. Such mineralogical changes evident in this study from petrography and SEM, includes cementation, authigenic quartz overgrowth and mineral replacement involving calcite and dolomite, which are typical of diagenesis. High concentration of chemical elements in the Montney Formation?-Ca and Mg indicates dolomitization. It is interpreted herein, that calcite may have been precipitated into the interstitial pore space of the intergranular matrix of very fine-grained silty-sandstone of the Montney Formation as cement by a complex mechanism resulting in the interlocking of grains.

^(13)C稳定同位素在陆地生态系统植物-微生物-土壤碳循环中的应用

绿色植物通过光合作用吸收大气中的CO_(2),是陆地生态系统的主要碳(C)源,量化光合C在植物-土壤系统间的分配,对于明确C的周转与存留、预测气候变化背景下植被和土壤C库潜力具有重要意义。^(13)C稳定同位素技术具有准确性和易操作性,在C循环研究中被广泛应用,为探究植物-土壤系统C分配、土壤微生物群落结构、C利用效率和土壤C矿化为CO_(2)通量变化等特性提供重要技术支撑。本研究首先介绍^(13)C稳定同位素的发展和标记方法,主要有^(13)C脉冲(单次与多次)标记、^(13)C连续标记、借助C_(4)土壤种植C_(3)植物确定^(13)C丰度以及不改变植被条件鉴定自然^(13)C丰度等。其次总结该技术在植物-微生物-土壤系统C循环中的应用:主要包括^(13)C同位素标记在植物-土壤系统C分配,^(13)C自然丰度技术在树木生长轮和植物群落水平C循环、土壤有机C形成与分解过程中的应用;在土壤微生物方面,概述^(13)C稳定同位素在磷脂脂肪酸、氨基糖、芯片-稳定同位素探针、纳米二次离子质谱同位素成像、荧光原位杂交-纳米二次离子质谱技术等微生物标志物上的应用。接着总结^(13)C稳定同位素方法的缺点,即^(13)C样品检测价格昂贵、由于^(13)C分馏作用影响^(13)C丰度检测不准确及^(13)C标记与微生物标志物技术结合对^(13)C标记丰度要求较高等。最后,对未来^(13)C同位素示踪技术研究提出展望:在理论上,需探究^(13)C标记底物在植物-土壤-微生物系统C分配、转化和固持的作用机制和影响机制,构建统计与验证模型;在应用上,应注重交叉学科的运用,将地理信息系统、遥感等地学技术与^(13)C稳定同位素相结合,从更广泛、更全面的角度推进陆地生态系统C循环研究。

广东湛江鲤鱼墩遗址人骨的C、N稳定同位素分析:华南新石器时代先民生活方式初探

相对于长江流域和黄河流域而言,华南地区先民生活方式的了解一直较为缺乏。广东湛江鲤鱼墩遗址人骨的C和N稳定同位素分析,显示此遗址的先民主要以海生类资源为食,陆生资源(包括可能的块茎类原始农业和动物)只占次要地位。通过与约同时代黄河流域、长江流域先民的稳定同位素数据比较,可以看出,早在6000年前,我国先民的生活方式就已出现3大类型。

中国古代儿童断奶模式与喂养方式初探——以安徽薄阳城遗址人骨的C、N稳定同位素分析为例

了解古代儿童的断奶模式和喂养方式,可望为揭示古代儿童的营养状况、生长发育以及其死亡原因提供有价值的重要信息。近些年来,通过对古代儿童骨骼的C、N稳定同位素分析,重建古代儿童的断奶模式和喂养方式,成为国际生物考古界的研究前沿,但在我国尚无任何相关报道。为此,本文以安徽滁州薄阳城遗址人骨(包含不同年龄阶段的儿童和成年人)样品为研究材料,通过对同一个体肋骨和肢骨的C、N稳定同位素分析和比较,重点探讨了我国西周时期儿童的断奶模式及喂养方式。研究结果显示:儿童在2岁已有辅食的摄入,大多数儿童在3-4岁已经完成断奶;断奶后的儿童,其食物中包含更多的植物作为辅食。本研究,印证了我国历史文献中有关儿童喂养模式的最早记载(唐代孙思邈的医书《千金方》),也为系统探索我国古代儿童的断奶模式和喂养方式提供了很好的范例。

湖泊环境早期成岩作用对沉积物中有机质C/N和碳同位素组成的影响

本文通过对青藏高原可可西里28个湖泊和中国东北地区26个湖泊表层沉积物中有机质C/N比值、有机碳同位素组成(δ^(13)C_(org)),以及有机质饱和烃组分特征的分析,探讨了这些参数对湖泊沉积物中有机质来源的指示和早期成岩作用对C/N、δ^(13)C_(org)的影响。研究表明,湖泊沉积物中有机质在迁移、聚集过程中早期成岩作用对有机质的作用比较明显,改变了沉积物中有机质C/N和δ^(13)C_(org),以至于影响这些参数对原始母质来源的判断。在有机质的演化过程中,沉水植物、藻类和C_4植物的降解作用最为强烈,初始有机质碳同位素组成可能在-17‰^-20‰;陆生植物C_3的降解作用相对较小,有机碳同位素组成的变化也相对较小,初始值可能在-26‰^-30‰;水生浮游、挺水植物的降解作用中等,有机碳同位素组成的变化中等,初始值可能在-20‰^-26‰。沉积物中早期成岩作用与有机质类型、湖泊水体性质、深度、滞留时间等有关,造成有机质C/N比值和碳同位素组成的降低,陆生植物来源的有机质碳同位素组成可能能更好地代表原始环境信息。

大气CH_4中碳稳定同位素组成的PreCon-GC/C-IRMS系统测定

利用预浓缩装置-气相色谱／燃烧-同位素比值质谱仪（PreCon-GC／C—IRMS）联用系统，建立了就采样、浓缩和在线质谱分析大气CH4中稳定碳同位素组成的测定方法。通过多组试验对比，分析并讨论了利用PreCon-GC／C-IRMS联用技术测定大气CH4中碳稳定同位素比值的试验条件、系统线性、稳定性及准确度和精密度等。结果表明，在本研究方法条件下，当离子流强度在1．0～20V时，系统线性良好（斜率S=0．04‰／V），在4．0～15V内其线性（斜率S=0．03‰／V）优于总体线性；系统测量稳定性可靠，δ^13C值的测定结果的S．D〈0．3‰，最大偏差〈0．5‰，回收率达99．99％，准确度和精度均符合分析与研究要求。利用该系统对室内和室外草坪地空气中CH4的碳稳定同位素组成做初步测试，其碳同位素的平均值分别为-31．358‰和-33．085‰，且相同地点区域空气中CH,的δ^13C值，在1d内和不同日期间的变化均在0．5％。以内，重现性良好。