浙江省不同地理尺度有机茶稳定同位素特征差异分析

为探究浙江省有机茶稳定同位素特征差异，本研究收集了来自浙江省52个有机茶企业生产的72份具有代表性的样品，采用元素分析-稳定同位素比率质谱仪测定有机茶中稳定同位素比值(δ¹⁵N、δ¹³C、δ²H、δ¹⁸O值)，研究不同茶类间的稳定同位素差异，并从3个地理尺度对浙江省有机茶稳定同位素特征进行分析。结果表明，浙江省有机绿茶和有机红茶的稳定同位素比值无显著差异。浙江省有机茶δ¹⁵N值范围为-2.4‰～6.7‰，平均值为2.0‰，在地市尺度上无显著差异；在区域尺度上，浙南地区有机茶δ¹⁵N显著高于浙北地区；在全国尺度上，浙江省有机茶δ¹⁵N显著高于全国其他产区。浙江省有机茶δ¹³C、δ²H、δ¹⁸O平均值分别为-27.2‰、-47.9‰、26.3‰，部分地市间存在地域差异，浙南地区和浙北地区有机茶的3种稳定同位素比值均无显著差异。本研究为浙江省有机茶稳定同位素数据库建立及特征识...     

有机物对红外光谱技术测定植物叶片和茎秆水δ18O和δD的影响

植物叶片、茎秆和土壤水δ18O和δD是研究土壤植被大气系统生态水文循环过程的重要示踪剂。与传统的稳定同位素质谱(IRMS)技术相比,稳定同位素红外光谱(IRIS)技术具有测量速度快、运行成本低等优势,将促进稳定同位素生态学的发展。但是利用低温真空蒸馏抽提技术获得的植物叶片和茎秆水中含有甲醇和乙醇类有机污染物,造成δ18O和δD的IRIS测量值偏离IRMS测量值(2.64±0.43)‰和(3.6±0.8)‰,超过了仪器精度。本研究利用纯水混入不同浓度的色谱纯甲醇或乙醇,结合Los Gatos公司的光谱分析软件确定甲醇(NB)和乙醇(BB)类物质污染程度的光谱度量值,建立了δ18O和δD的光谱污染校正方法。研究表明,同一台分析仪建立的校正曲线无明显的时间漂移;不同分析仪建立的校正曲线存在显著差异;IRIS校正值与IRMS测量值的交叉验证表明,IRIS测定冬小麦和夏玉米叶片和茎秆水的δ18O和δD可以被准确地校正,与IRMS的差值分别为(0.11±0.12)‰和(0.7±0.4)‰。     

氨基酸δ~(13)C在关键种鳀鱼食物链中的示踪研究

为了解关键种鳀鱼食物链的氨基酸营养流动机理,采用活体生物对黄东海食物网关键种食物链的中下营养层次"浮游植物-中华哲水蚤-鳀鱼"进行受控试验研究,培养50d后,对采集样品做生物整体(组织)碳稳定同位素值(δ~(13)C)和12种氨基酸δ~(13)C值测定分析。结果表明,3种样品中12种单体氨基酸的δ~(13)C值模式相似,三者氨基酸δ~(13)C值平均变化幅度均较大;整体生物或组织δ~(13)C值顺序为:鳀鱼肌肉中华哲水蚤小球藻;营养层次间必需氨基酸δ~(13)C值相关性强,非必需氨基酸δ~(13)C值相关性较弱;各营养层次生物样品间,必需氨基酸δ~(13)C分馏值(Δδ~(13)C)跟0‰无显著差异,非必需氨基酸Δδ~(13)C值与0‰有较大偏差。由此可知,模拟食物链必需氨基酸传递效率高,非必需氨基酸来源复杂,可能来自自身合成、直接食物转移等途径。本研究为采用氨基酸δ~(13)C进行食物网营养生态学研究提供了参考依据。     

北京山区侧柏生态系统各组分夜间δ13C变化特征和对环境因子的响应

采用同位素光谱测定仪对北京山区侧柏人工林生长旺盛期夜间CO_2浓度和δ~(13)C进行原位观测。分析侧柏林生态系统不同组分夜间呼吸δ~(13)C的差异,探究其对环境因子的响应。结果表明:在使用Keeling plot法拟合侧柏林7—9月夜间呼吸作用释放的δ~(13)C时,利用大气稳定度作为筛选条件后,拟合精度从0.43增大到0.82,误差从0.54‰～0.99‰下降到0.50‰～0.82‰。δ~(13)C变化范围为(-28.76±0.51)‰～(-25.18‰±0.59)‰,呈现先增大后减小的趋势;地上侧柏枝条δ~(13)C_(地上)变化范围(-33.16±1.08)‰～(-26.82±0.18)‰,呈增加趋势,在7月底达到最大值,9月变化趋于平稳;地下土壤δ~(13)C_(地下)变化范围(-28.55±0.17)‰～(-21.39±0.37)‰,呈增加趋势,7月底达到最大值,变化波动最大,9月变化趋于平稳,各月δ~(13)C与时间呈二次函数关系;在生长旺盛期夜间土壤呼吸通量占生态系统呼吸通量的54.77%,δ~(13)C_(地下)比δ~(13)C_(地上)高2.06‰～7.03‰;逐步回归分析表明,夜间呼吸δ~(13)C受大气湿度影响最显著,大气湿度对各组分碳同位素值变化的贡献率均在60%以上。δ~(13)C_(地下)不受土壤温度的影响,δ~(13)C_(地上)除大气湿度外,大气温度、土壤温湿度对其影响较为均衡。通过对夜间呼吸δ~(13)C的研究,可以更全面地评估北京山区森林生态系统碳平衡,为区域森林生态系统经营提供科学依据。     

荒漠草原土壤有机质碳稳定同位素特征研究

应用碳稳定同位素分析方法对内蒙古短花针茅荒漠草原土壤有机质及其δ13 C值垂直分布特征、表土δ13C值与建群种-短花针茅δ13 C值的相互关系进行分析,并测定土壤部分理化性质。结果显示:表土有机质含量变化范围为4.17～20.45g/kg;随深度增加,土壤有机碳(SOC)含量呈指数降低,其变化范围为17.98～1.39g/kg,而δ13C值则随剖面深度增加而明显富集,到75cm深度时δ13C值又迅速降低,变化范围为-26.38‰～-13.72‰,变幅>3‰,说明该地区气候和植被状况可能发生过剧烈变化;表土和植物δ13C值分馏程度较其它地区偏大,二者呈极显著相关(r=0.555,P<0.01),进一步说明地上植被状况是影响土壤有机质δ13 C值垂直分布特征的决定性因素。     

放牧干扰对若尔盖高寒湿地不同水生生物δ~(13)C、δ~(15)N的影响

为了解畜牧业发展对若尔盖湿地水生生物类群的影响,本试验设置了A(对照组),B(影响组I),C(影响组II)3个样点,应用稳定同位素技术并结合多维尺度(MDS)等方法研究了若尔盖湿地影响组与对照组之间不同水生生物类群δ~(13)C、δ~(15)N值。结果表明,初级生产者POM(颗粒有机物)样品(主要成分为藻类)δ~(13)C、δ~(15)N值分别为-26.39‰~-21.17‰,3.68‰~6.61‰;浮游动物(枝角类)δ~(13)C、δ~(15)N值分别为-25.69‰~-23.43‰、3.19‰~9.53‰;软体动物泉膀胱螺δ~(13)C、δ~(15)N值分别-28.00‰~-22.30‰、5.19‰~9.27‰,钩虾为-28.57‰~-26.87‰、7.36‰~8.06‰;鱼类样品中高原鳅δ~(13)C、δ~(15)N值分别-30.83‰~-27.01‰、6.41‰~10.02‰,黄河裸裂尻为-26.89‰~-25.95‰、10.24‰~10.89‰。其中不同组间POM样品和浮游动物δ~(13)C值变化不明显,而其δ~(15)N值变化极显著。因此,若尔盖湿地食物网中,氮稳定性同位素信号能较灵敏地反映放牧干扰信息,与软体动物、鱼类相比,POM、浮游动物更适合作为该区域环境评价的指示物种。放牧干扰已经对若尔盖湿地POM、浮游动物等产生了一定的影响,因此,控制若尔盖湿地放牧规模和减少动物粪便的流入量,对于保护若尔盖湿地生态系统的稳定性具有重要意义。     

北京山区侧柏林蒸散组分d18O的确定及其定量区分

基于稳定同位素技术,对北京山区侧柏林蒸散各组分的δ~(18)O 进行了确定,并定量区分了蒸散量中蒸腾量和蒸发量所占的比例。在对侧柏林大气水汽氧同位素组成δV进行原位连续观测的同时,选择典型晴天对侧柏枝条和土壤进行野外采样,并结合室内分析分别获得了枝条和土壤水中的氧同位素值。结果显示:(1)用Craig-Gordon方程估测的4个测定日δE介于(-20.26‰)~(-17.48‰),δS介于(-5.22‰)~(1.75‰),δV介于(-19.09‰)~(-16.21‰),δSδVδE。表明在蒸发过程中,土壤蒸发水汽~(18)O 明显贫化;(2)基于稳态假设,4个测定日侧柏林δT介于(-7.31‰)~(-2.09‰);用Keeling曲线拟合的δET介于(-8.21‰)~(-3.84‰),且方程的相关性均大于0.89,δEδETδT,说明日中时满足氧同位素稳态假设;(3)在获得了δE、δT及δET的情况下,对侧柏林蒸散量进行定量区分的研究结果显示:4个测定日侧柏林蒸腾量占总的蒸散量的比例介于85.37%~93.04%。研究结果表明,侧柏林蒸腾量是蒸散量的主要组成部分,蒸腾耗水远远大于蒸发耗水。     

丹江流域氢氧同位素变化特征

沿丹江干流自上游到下游每5km采集水样,并在丹江上中下游小流域沿河采集水样的同时分别在沿岸选择林地、草地和农地,采集土壤样品。通过相关性分析和ANOVA分析等方法研究丹江流域氢氧同位素的变化特征和影响因素。结果表明:丹江流域大气降水的氢氧同位素变化呈现出高度效应,高程、温度和距离对丹江流域水体的氢氧同位素特征影响较大;δD值与高程呈极显著水平负相关(P0.01,n=25),而与水温呈极显著水平正相关(P0.01,n=25),氢氧同位素特征表明蒸发分馏作用在较宽及流速小的河面更强烈;丹江干流水体中δD和δ18 O的分布范围分别为(-60.98‰)~(-53.34‰)和(-9.12‰)~(-7.89‰),其平均值分别为-56.20‰和-8.29‰。随着采样点位置到丹江源头距离的增加,δD值逐渐增大,其线性拟合方程为y=0.0268x-59.435,拟合度R2为0.62;林地和草地0-10cm土壤水分的氢氧同位素变化范围较农地大,农地0-10cm土壤水分的氢氧同位素值相对集中,ANOVA分析表明,丹江上中下游小流域0-10cm土壤水分的氢氧同位素特征存在极显著差异(P0.01,n=42)。     

稳定性同位素~(13)C标记小麦植株δ~(13)C值的检测方法研究

为准确检测稳定性同位素13C标记的小麦植株δ13C值,对元素分析仪-同位素比质谱仪联用技术(EA-IRMS)测定13C标记的小麦植株各器官中δ13C值进行了研究。结果表明,该方法对蔗糖标准物质(IAEA-CH-6)、小麦粉标准物质(OAS/Isotope)和13C标记小麦植株样品测定结果的精度良好,稳定性碳同位素的标准偏差小于0.11‰。对仪器的稳定性进行了测试,标准偏差为0.02‰;同位素信号在1e-9至1e-8A范围内,总体线性为0.003‰·n A-1。测得样品δ13C值的范围为-25.25%~23.32%。试验结果为研究光合产物在小麦植株体内的运转分配提供了可靠的技术支撑。     

东北三省和浙江木耳稳定同位素特征与产地溯源

为探究稳定同位素在黑木耳产地溯源中的可行性,本研究从东北(黑龙江、吉林、辽宁)、浙江产地采集74份代表性黑木耳样品,从新疆采集11份代表性黑木耳样品作为外部验证,采用元素分析-稳定同位素比率质谱仪测定δ¹³C、δ¹⁵N、δ²H、δ¹⁸O值,结合化学计量学方法进行产地溯源判定。结果表明,东北黑木耳δ¹³C、δ¹⁵N、δ²H、δ¹⁸O值分别为-24.5‰～-22.7‰、-0.9‰～3.1‰、-62.2‰～-34.6‰、15.9‰～19.4‰;浙江黑木耳δ¹³C、δ¹⁵N、δ²H、δ¹⁸O值分别为-26.2‰～-24.5‰、-0.9‰～1.2‰、-24.9‰～-9.0‰、19.9‰～22.2‰,两产地黑木耳δ¹⁵N值差异不显著(P>0.05),δ¹³C、δ²H和...     

Carbon and nitrogen natural stable isotopes in Slovene honey: adulteration and botanical and geographical aspects

Isotope parameters (δ(13)C(honey), δ(13)C(protein), δ(15)N) were determined for 271 honey samples of 7 types (black locust, multifloral, lime, chestnut, forest, spruce, and fir honeys) from 4 natural geographical regions of Slovenia. Carbon and nitrogen stable isotope ratios were measured to elucidate the applicability of this method in the identification of the botanical and geographical origin of honey and in honey adulteration. Only 2.2% of the samples were adulterated according to the internal standard carbon isotope ratio analysis method. Botanical origin did not have any major influence on the honey isotope profiles; only black locust honey showed higher δ(13)C values. Some differences were seen across different production years, indicating that the influence of season should be further tested. Statistical and multivariate analyses demonstrated differences among honeys of various geographical origins. Those from the Alpine region had low δ(13)C (-26.0‰) and δ(15)N values (1.1‰); those from the Mediterranean region, high δ(13)C (-24.6‰) and medium δ(15)N values (2.2‰); those from the Pannonian region, medium δ(13)C (-25.6‰) and high δ(15)N value (3.0‰); and those from the Dinaric region, medium δ(13)C (-25.7‰) and low δ(15)N values (1.4‰).     

Responses of herbage and cattle tail switch hair δ15N value to long-term stocking rates on a rough fescue grassland

The purpose of this study was to investigate the response of δ¹⁵N in herbage and cattle tail switch hair to long-term grazing pressure on a rough fescue grassland (Festuca campestris Rydb.) near Stavely, Alberta, Canada. Cattle have grazed the paddocks from 15 May to 15 November annually since 1949. Stocking rates were 0, 2.4 and 4.8 animal unit months ha^?1 for non-grazing (Control), moderate grazing (MG) and heavy grazing (HG), respectively. Green standing crop (GSC) was sampled monthly throughout the grazing season in 2007. The GSC was fractioned into neutral detergent fiber (NDF), acid detergent fiber (ADF), and their total nitrogen (TN) concentration and δ¹⁵N values in NDF, ADF and GSC were determined. Tail switch hair samples from cows (>2 years old) and calves (<1 year) were collected at the end of the grazing season in 2007 and 2008 and analysed for δ¹⁵N values. The TN concentrations in NDF and δ¹⁵N values in herbage NDF and ADF fractions were higher (P?15N values in tail hair also decreased (P?15N values in tail hair increased with herbage δ¹⁵N values. The δ¹⁵N values in tail hair were enriched by +5.2‰ compared to herbage δ¹⁵N values in 2007. Changes in δ¹⁵N value in GSC and cattle hair reflect the influence of grazing practices on N cycles through the animal/plant/soil system on this rough fescue grassland.     

北京郊区有机蔬菜土壤养分平衡及δ^15N特征分析

本研究针对北京郊区汇源与正谷有机蔬菜基地,通过对不同蔬菜生产基地取样分析,研究有机和常规蔬菜生产条件下土壤养分平衡特征,分析有机生产蔬菜和土壤的15N特征。结果表明,（1）有机蔬菜生产与常规生产对比,由于施肥数量不同,汇源有机蔬菜基地土壤N、P及K盈余量（分别为356～472kg·hm-2、298kg·hm-2和200～226kg·hm-2）高于当地常规生产,而正谷有机蔬菜生产土壤N、P及K养分盈余量（分别为-164～190kg·hm-2、107.9～435.5kg·hm-2和-164.5～-136.8kg·hm-2）低于当地常规生产;（2）汇源有机蔬菜生产模式中,土壤N素养分有逐季累积的趋势,有机肥的N、P和K养分存在着不平衡性,这可能是造成0～20cm土层磷素大量累积的重要原因;（3）蔬菜类别不同,δ15N值不同,一般为叶菜类最高（10.49‰）,果菜类次之（10.07‰）,根菜类δ15N值最低（5.62‰）;（4）植物不同部位δ15N值也有差异。针对圆椒的分析表明,圆椒叶δ15N（12.44‰）〉圆椒果实δ15N（9.35‰）;（5）土壤δ15N与土壤全N之间有一定的相关性,回归方程为δ15N土壤=13.098N土壤＋3.7624,R2=0.938,而植物δ15N与土壤δ15N之间、植物δ15N与土壤全氮相关性较差。长期施用有机肥,使得土壤中15N更多来自有机肥,进而表现为蔬菜δ15N升高,高量有机肥可以短期内增加叶菜类植物δ15N值。     

不同放牧强度下荒漠草原土壤有机碳及其δ~(13)C值分布特征

以内蒙古短花针茅荒漠草原为研究对象,通过测定不同载畜率下土壤部分理化性质、土壤有机碳含量和δ~(13)C值.探讨随放牧强度增加土壤有机碳深度分布和δ~(13)C值的组成差异特征.结果显示:随深度增加.有机碳含量呈线性急剧降低,变化范围在16.17～6.26 g/kg之间,而土壤有机碳的δ~(13)C值不断增大.变化范围在-22.5‰～-14.3‰.放牧对土壤有机碳的影响主要在0-20 cm土层,且放牧强度越大,有机碳含量越低,有机质分解程度越大,δ~(13)C值越偏正,δ~(13)C值的深度变化特征还表明.土壤剖面形成发育过程中当地气候和植被发生了很大的变化,可能实现了由C_4植物占优势向C_3植物占优势的变迁.     

A review of phosphate oxygen isotope values in global bedrocks: Characterising a critical endmember to the soil phosphorus system

Understanding the phosphate oxygen isotope (δ¹⁸O‐PO₄) composition of bedrock phosphate sources is becoming ever more important, especially in areas of soil research which use this isotope signature as a proxy for biological cycling of phosphorus (P). For many of these studies, obtaining a sample of the source bedrock or applied mineral fertiliser for isotope analysis is impossible; meaning there is now a demand for a comprehensive characterisation of global bedrock δ¹⁸O‐PO₄ to support this work. Here we compile δ¹⁸O‐PO₄ data from a wide range of global bedrocks, including 56 new values produced as part of this study and a comprehensive overview of those within the previously existing literature. We present δ¹⁸O‐PO₄ data from the range of major phosphatic lithologies alongside as much metadata for the samples as could be gathered. Much of the data comes from bedrocks of marine sedimentary origin (< 1 Ma = > +22‰, > 540 Ma = ≈ +12‰), but we also present data from bedrocks associated with guano (range: +19.5 to +15‰) and igneous deposits (range: +12 to –0.8‰), both of which have distinct δ¹⁸O‐PO₄ signatures due to their formation mechanisms. We show that where repeat measurements of the same formation have been undertaken, regardless of method or exact sample location, there is an average within formation error of ± 1.25‰. This is important, as is constitutes a reasonable level of uncertainty for phosphorus cycling studies which need to estimate bedrock δ¹⁸O‐PO₄ composition based on the literature. In combination, this data set presents 284 δ¹⁸O‐PO₄ values from 56 countries; a comprehensive starting point for researchers interested in understanding bedrock end member δ¹⁸O‐PO₄.     

Intramolecular carbon isotope distribution of acetic acid in vinegar

Compound-specific carbon isotope analysis of acetic acid is useful for origin discrimination and quality control of vinegar. Intramolecular carbon isotope distributions, which are each carbon isotope ratios of the methyl and carboxyl carbons in the acetic acid molecule, may be required to obtain more detailed information to discriminate such origin. In this study, improved gas chromatography-pyrolysis-gas chromatography-combustion-isotope ratio mass spectrometry (GC-Py-GC-C-IRMS) combined with headspace solid-phase microextraction (HS-SPME) was used to measure the intramolecular carbon isotope distributions of acetic acid in 14 Japanese vinegars. The results demonstrated that the methyl carbons of acetic acid molecules in vinegars produced from plants were mostly isotopically depleted in (13)C relative to the carboxyl carbon. Moreover, isotopic differences (δ(13)C(carboxyl) - δ(13)C(methyl)) had a wide range from -0.3 to 18.2‰, and these values differed among botanical origins, C3, C4, and CAM plants.     

Beef authentication and retrospective dietary verification using stable isotope ratio analysis of bovine muscle and tail hair

Stable isotope ratio analysis (SIRA) was used as an analytical tool to verify the preslaughter diet of beef cattle. Muscle and tail hair samples were collected from animals fed either pasture (P), a barley-based concentrate (C), silage followed by pasture (SiP), or silage followed by pasture with concentrate (SiPC) for 1 year (n = 25 animals per treatment). The (13)C/(12)C, (15)N/(14)N, (2)H/(1)H, and (34)S/(32)S isotope ratios in muscle clearly reflected those of the diets consumed by the animals. By applying a stepwise canonical discriminant analysis, a good discrimination of bovine meat according to dietary regimen was obtained. On the basis of the classification success rate, the (13)C/(12)C and (34)S/(32)S ratios in muscle were the best indicators for authentication of beef from animals consuming the different diets. Analysis of (13)C/(12)C and (15)N/(14)N in tail hair sections provided an archival record of changes to the diet of the cattle for periods of over 1 year preslaughter.     

主要人为排放源中氮氧化物~(15)N自然丰度的测定

氮氧化物(NO_x=NO+NO_2)因其对环境和人类健康的威胁,成为大气中需要严格控制的一种痕量组分。首次运用化学转化法,通过将主要人为排放源废气中的氮氧化物(NO_x)转化为氧化亚氮(N_2O),测定气体中NO_x的15N自然丰度,即氮稳定同位素比值(δ15N-NO_x)。利用酸性氧化剂将NO_x氧化为硝酸(NO_3~-),并通过三氯化钒(VCl_3)和叠氮钠(NaN_3)的共同作用将其转化为N_2O,利用带有自动预浓缩装置的稳定同位素比值质谱计(PT-IRMS)测定δ15N-NO_x。该方法的测量精度可达0.09‰,所需样品量仅为7μg(以氮计),对火力发电站、机动交通工具等人为排放源均适用,测量精度和准确度可满足NOx相关研究的需求。