稳定性氮同位素技术研究太湖梅梁湾区域营养盐差异

稳定同位素技术通常用于指示外源输入对环境的影响,采用该技术分析了太湖北部不同湖区悬浮颗粒有机物和浮游动物的碳氮稳定同位素比值的差异。结果表明,不同粒径的悬浮颗粒有机物和浮游动物稳定同位素比值存在显著的季节变化,夏季普遍高于冬季,其中δ13C高3.19‰~7.21‰,δ15N高4.20‰~9.36‰。各有机物δ13C不能有效区分各湖区的环境差异,而δ15N在各湖区存在显著差异。δ15N聚类分析显示,河口区由于受外源输入的影响,其δ15N显著低于其他湖区,单独聚为一类,而交汇处和湖心区影响较小,同河口区存在显著差异。整体来讲,总颗粒有机物和浮游动物δ15N同水体TP浓度呈显著正相关,同总溶解性无机氮浓度、铵根离子浓度呈显著负相关。可见,太湖北部悬浮颗粒有机物和浮游动物δ15N受环境营养盐差异的影响强烈,悬浮颗粒有机物δ15N可以作为指示湖区区域差异的有效指标。     

运用稳定同位素技术研究千岛湖秋季刺网渔获物的食性和营养级

利用稳定性同位素技术,对2011年9月至11月期间利用浙江千岛湖主要渔具之一的刺网采集的渔获物开展了食物源和营养级的分析研究。结果表明,千岛湖鱼类主要食物源的δ13C值跨度范围较大(-29.7‰~-23.9‰),其中浮游植物的δ13C值最高,颗粒有机物(POM)的δ13C值最低。食物源的δ15N值变化范围较小,以浮游植物最高(8.5‰),颗粒有机物最低(5.1‰)。与食物源的同位素值分布趋势相反,消费者的δ13C值浮动范围相对较小(-29.7‰~-21.6‰),而δ15N值的浮动范围相对较大(5.1‰~14.8‰)。消费者的营养级从1.9到3.6,分属于3个营养等级,鱼类的营养级全部分布在第3到第4营养级之间,且与其食性特征有较好的一致性,但是两种外来种鱼类中的一种草食性鱼类团头鲂的营养级却高达3.4,而肉食性的斑点叉尾的营养级则仅为3.0,说明其在千岛湖的食性均已发生了很大变化。同位素示踪方法研究的结果还表明千岛湖水体中的碳源主要是浮游植物。     

Soil Organic Carbon Sequestration Potential in Nectarine Orchards under Different Reclamation Systems

The Red Soil Hilly Region in South China, where there is a high capacity of carbon(C), and the land use and vegetation cover change greatly, is an important ecological area in the world, and has an important impact on the global carbon cycle and the seasonal fluctuation of atmospheric CO_2. To better evaluate the effects of reclamation systems in orchards converted from grasslands on soil carbon sequestration, we investigated soil organic carbon(SOC) content and stable C isotope(δ~(13)C)composition in three nectarine orchards at Yuchi Experimental Station in South China. Compared with the sloping clean tillage orchard and terraced clean tillage orchard, SOC content in the terraced orchard with grass cover was increased by 14.90% to 38.49%, and 7.40% to 15.33%, respectively. During the 14 years after orchard establishment, the soil organic matter sources influenced both δ~(13)C distribution with depth and carbon replacement. SOC turnover of the upper soil layer in the terraced orchard with grass cover(a mean 63.05% of replacement in the 20 cm after 14 years) was 1.59 and 1.41 times larger than that of the sloping clean tillage orchard and terraced clean tillage orchard under subtropical conditions, respectively. The equilibrium value of soil organic carbon in the three treatments ranged from 16.067 to 25.608 g/kg under the experimental conditions. The equilibrium value of soil organic carbon in the surface layer under grass cover was 54.801 t/hm~2, and the carbon sequestration potential was 24.695 1 t/hm~2.     

Carbon isotope constraints on the deglacial CO₂ rise from ice cores

The stable carbon isotope ratio of atmospheric CO(2) (δ(13)C(atm)) is a key parameter in deciphering past carbon cycle changes. Here we present δ(13)C(atm) data for the past 24,000 years derived from three independent records from two Antarctic ice cores. We conclude that a pronounced 0.3 per mil decrease in δ(13)C(atm) during the early deglaciation can be best explained by upwelling of old, carbon-enriched waters in the Southern Ocean. Later in the deglaciation, regrowth of the terrestrial biosphere, changes in sea surface temperature, and ocean circulation governed the δ(13)C(atm) evolution. During the Last Glacial Maximum, δ(13)C(atm) and atmospheric CO(2) concentration were essentially constant, which suggests that the carbon cycle was in dynamic equilibrium and that the net transfer of carbon to the deep ocean had occurred before then.     

桂林岩溶土壤和植被的稳定碳同位素组成及季节性变化特征

【目的】以桂林岩溶土壤为例,通过长期监测岩溶土壤及植被有机碳的δ13C值,研究其稳定碳同位素组成及季节性变化特征,为我国南方岩溶地区碳循环途径提供科学依据。【方法】选择3个试验点,定期采集土壤及优势种植被黄荆和檵木样品,测定有机碳含量和δ13C值。【结果】土壤有机碳的δ13C值具有明显的季节性变化特征,范围在-27.50‰～-17.92‰;优势种黄荆和檵木其各部位有机质的平均δ13C值范围为-28.23‰～-25.15‰,而土壤中有机碳的δ13C值范围为-22.32‰～-19.00‰;土壤有机碳的含量表现为洼地灌木丛〉坡地灌木丛〉洼地灌草丛,且都为表层土（0～5cm）〉深层土（10～20cm）。【结论】土壤有机碳的δ13C值变幅较大,但坡地灌木丛、洼地灌木丛和洼地灌草丛三者的变化规律并不一致;总体上土壤δ13C值随土层深度的增加而逐渐减小,表明土壤有机碳的δ13C值明显高于当地植被有机碳的δ13C值。     

小麦籽粒氨基酸碳氮稳定同位素的测定与分析

 【目的】利用气相色谱-燃烧-同位素比值质谱仪（gas chromatography-combustion-isotope ratio mass spectrometry,GC-C-IRMS）测定小麦籽粒氨基酸碳氮稳定同位素组成。【方法】以小麦临汾50744为材料,水解得到其籽粒蛋白质氨基酸,将氨基酸标准样品以及小麦籽粒氨基酸衍生化为N-新戊酰基,O-异丙醇（N-pivaloyl-isopropyl,NPP）氨基酸酯,利用GC-C-IRMS测定其碳氮稳定同位素组成。【结果】氨基酸标准样品的碳氮同位素组成分析表明,NPP氨基酸酯的平均重现性δ13C为0.47‰,δ15N为0.28‰,并没有产生大的同位素分馏,因此δ13C和δ15N都能得到满意的测定结果。运用GC-C-IRMS测定了小麦临汾50744籽粒蛋白质氨基酸的稳定碳氮同位素的自然丰度,其中δ13C的变化范围在-28.7‰到-34.7‰,δ15N的变化范围为-6.2‰到9.5‰。采用系统聚类分析进行分类,根据δ13C可以将氨基酸分为两类;根据δ15N可以将氨基酸分为三类。【结论】运用GC-C-IRMS结合NPP氨基酸酯衍生物可以测定小麦籽粒氨基酸的稳定碳氮同位素,这对于揭示氨基酸代谢途径的差异以及逆境胁迫下氨基酸的合成差异具有重要的意义。     

饲料中C3植物含量对牛组织中稳定同位素碳、氮组成的影向

研究了饲料中C3植物含量不同时对牛不同组织中稳定性同位素碳、氮组成的影响。18头12~14月龄的青年牛随机分为6组,分别饲喂C3植物含量为50.0%、60.0%、70.0%、80.0%、90.0%、100.0%的饲料,132 d后屠宰。利用同位素比值质谱仪测定了牛尾毛、脱脂牛肉、粗脂肪、各种饲料的δ13C和δ15N值。结果表明,牛组织中碳同位素主要受饲料的影响,牛尾毛、脱脂肌肉、粗脂肪中的δ13C值随着C3植物含量在牛饲料中的比例增大而降低,并且均与C3植物含量呈极显著的负相关关系,用牛组织中的δ13C值可以预测饲料中C3植物所占的比例。牛组织中的氮同位素一定程度上受饲料因素的影响,但未随C3植物含量呈现规律性变化。牛不同组织中δ13C和δ15N与饲料之间的富集或贫化比例与其他报道并不一致。     

植物δ~(13)C与土壤盐分的关系研究综述

稳定碳同位素组成(δ13C)综合反映了植物的生理生态特征,可用于研究植物生理与生态环境之间的关系。大多数研究认为植物δ13C值随盐度增加而变重。盐分主要通过影响C3植物叶片气孔传导、光合作用等生理活动,使植物δ13C值发生变化。而有些植物为适应盐分胁迫可能发生光合途径的转换,使C3代谢转换成C4或CAM代谢,导致植物某些器官的δ13C值发生变化,而植株整体δ13C值变化较小。由于植物δ13C与土壤盐分的关系还受其他环境因素的影响以及室内试验的有限性,因此进一步扩大盐度梯度范围,延长盐处理时间以及开展大田试验显得很有必要。     

植物叶片水平δ13C与水分利用效率的研究进展

水分限制可能因全球气候变化加剧成为限制植物生产力的主要原因,因此,如何提高植物水分利用效率(WUE)是未来一个主要研究目标。WUE能够反映植物-土壤-大气之间的碳水循环的耦合状况,研究WUE有助于了解陆地生态系统碳水耦合机制。稳定性碳同位素技术已成为研究生态系统养分循环最有效的方法之一,也被利用到植物水分利用效率中。研究表明,植物叶片的稳定碳同位素比值(δ13C)是植物长期水分利用效率(WUE)的良好指标。本文综述了δ13C表征WUE的机制,植物δ13C和WUE的影响因子(包括:叶片结构性状、植物生理生态、气候因子、基因控制和遗传变异),分析了水分胁迫及酸沉降条件下植物的δ13C和WUE变化特征,并对全球气候变化下植物δ13C和WUE的研究进行了展望。指出气孔导度、比叶面积、叶片氮含量、细胞间CO₂浓度和大气CO₂浓度等因子可直接或间接作用植物的光合速率和蒸腾速率,从而引起WUE的变化。一般情况下,植物在干旱条件下具有更高的WUE和更低的δ13C,长期酸沉降下植物的气孔导度和光合作用均会下降,氮的输入可以通过改善水分利用效率来提高植物的生产力。建议为更清晰地认识全球气候变化,在利用稳定性同位素技术进行WUE研究过程中,需要突出数量性状基因座(QTL)、碳酸酐酶、水孔蛋白和光合羧化酶的大小亚基基因在遗传控制方面起到的关键作用,加强多时空尺度的关联研究,探索双重稳定同位素(δ13C、δ18O)概念模型的应用。      

羊组织中碳、氮同位素组成及地域来源分析#br#

 【目的】探讨羊组织中C、N同位素组成特征及其在地域间的变化规律,为利用稳定性同位素技术进行羊肉产地溯源提供科学依据。【方法】利用稳定性同位素比率质谱仪（IRMS）测定来自内蒙古自治区锡林郭勒盟、阿拉善盟和呼伦贝尔市3个牧区,重庆市和山东省菏泽市2个农区羊肉、羊颈毛及饲料样品中的δ13C和δ15N值,比较不同地域羊组织中稳定性碳、氮同位素组成的差异,分析羊组织同位素组成的相关关系,结合羊的饲喂方式和地域环境,探讨C、N同位素组成的变化规律。【结果】不同地域羊组织的δ13C、δ15N值有显著性差异,其δ13C值与牧草δ13C值高度相关,主要受牧草种类的影响;δ15N值与饲料和地域环境有关。脱脂羊肉、粗脂肪及羊颈毛的δ13C、δ15N值均呈极显著性相关。【结论】稳定性C、N同位素可以作为追溯羊肉产地及其饲喂体系的参考指标。脱脂羊肉、羊颈毛、粗脂肪均可用于羊肉产地溯源研究。     

日粮中玉米含量对肉鸡碳·氮同位素组成的影响

[目的]研究日粮中玉米含量对肉鸡肌肉中δ^23 C和分δ15 N值的影响。[方法]以不同玉米含量的基础日粮饲喂160只1日龄的从肉鸡21d,然后更换日粮继续饲喂21d,取其胸部肌肉测定稳定性碳和氮同位素组成。[结果]结果表明：在试验的前21d鸡肉中δ^13 C的值与基础日粮中δ^13 C的值呈显著正相关（相关系数达0．97,P〈0．01）;更换基础日粮后,鸡肉中δ^13 C的值与日粮中δ^15 C的值仍呈高度正相关（相关系数达0．84,P〈0．01）,而鸡肉中δ^15N值无明显的变化规律。[结论]基础日粮中玉米含量决定了鸡肉中稳定性碳同位素的组成,而鸡肉中稳定性氮同位素的组成受日粮中玉米含量的影响较小。     

芒果品种资源叶片δ~(13)C与若干生理指标的相关性分析

为了分析芒果品种植株叶片碳稳定性同位素(δ13C)与叶片若干生理指标的相互关系,测定64个芒果品种的δ13C值,及叶片中氮、磷、钾、水分、叶绿素和脯氨酸的含量。结果表明:芒果叶片δ13值与叶片含水量、叶绿素a、叶绿素b、总叶绿素和脯氨酸含量的相关性均不显著;芒果叶片氮、磷、钾含量均与δ13C值呈显著的正相关(P0.05);多元逐步回归分析结果表明,叶片氮含量是引起品种间δ13C差异的主要因素。     

用δ~(13)C值研究土壤有机质周转的方法及其评价

介绍了用δ13C值研究土壤有机质周转的原理、方法和应用实例 ,讨论了不同条件下植物和土壤有机质的δ13C值 ,并对此方法进行了评价。     

碳、氮同位素在牛肉产地溯源中的应用研究

【目的】探索稳定性同位素对中国牛肉产地溯源的可行性，了解牛不同组织中δ13C和δ15N指标在其中的作用。【方法】利用同位素比率质谱仪测定了来自吉林、贵州、宁夏、河北4个地域牛肉、牛尾毛、饲料中的δ13C和δ15N值，比较了不同地域牛组织中稳定性碳、氮同位素组成的差异，分析了各组织中同位素组成的相关关系，并结合牛的喂养方式，研究了δ13C和δ15N值的变化规律。【结果】不同地域牛组织中稳定性碳同位素组成有极显著差异，排序依次为吉林>贵州>宁夏>河北。吉林、宁夏两地样品与贵州、河北两地样品之间的δ15N值有极显著差异，且后者高于前者。不同地域喂养牛的主饲料成分有其明显的地域特征。脱脂牛肉粉、粗脂肪、牛尾毛中碳、氮同位素之间呈极显著相关性。【结论】牛组织中δ13C值可预测其膳食中C4植物所占的比例，δ15N值可区分牧区与农区喂养的牛；δ13C指标对牛肉产地来源的正确判别率高于δ15N指标，两项指标相互补充可显著提高产地来源的正确判别率；脱脂牛肉粉、粗脂肪、牛尾毛中δ13C、δ15N值均可作为牛肉产地溯源的指标，它们对牛肉产地来源的判别规律一致。     

Soil carbon isotope evidence for holocene habitat change in the kenya rift valley

In eastern Africa the altitude of the boundary between montane forest and lowland savanna grassland changed substantially in response to climate change during the later Holocene, but this is not clearly reflected in regional pollen records. The carbon-13 to carbon-12 ratios of tropical grasses are higher than those of most other plants, and this difference is preserved in soil organic carbon stable isotope ratios. Soil organic matter (13)C/(12)C ratios in profiles along an altitude transect in the central Rift Valley of Kenya suggest that the forest-savanna boundary advanced more than 300 meters in altitude. This could have implications for understanding the effects of climate change on the configuration of floral zones, prehistoric hunter-gatherer land-use patterns, and the timing of the advent of Neolithic food production.     

水分胁迫下7个种源辽东冷杉幼苗水分利用效率差异

以来自辽东冷杉天然分布区之一的辽宁省东部山区的7个种源辽东冷杉当年实生幼苗为研究对象,在温室控制条件下研究了辽东冷杉幼苗在充分供水、轻度胁迫、重度胁迫共3个水分处理条件下的长期水分利用效率(WUEL)、瞬时水分利用效率(WUEI)、叶片稳定碳同位素组成(δ13C)及相互关系,以探讨辽东冷杉幼苗水分利用效率的种源间差异及其对水分胁迫的生理响应机制。结果表明,随着水分胁迫的加剧,7个种源辽东冷杉幼苗的WUEL均呈上升趋势,种源间WUEL仅在重度胁迫条件下差异显著(P0.05),在充分供水和轻度胁迫条件下,种源间WUEL的差异并不显著;WUEI和叶片δ13C也均呈上升趋势,种源间WUEI和叶片δ13C在3种水分条件下的差异均极显著(P0.01)。从单个种源在3种水分条件下的表现来看,WUEL在水分处理间均存在显著(P0.05)或极显著差异(P0.01),而WUEI和叶片δ13C在水分处理间均存在极显著差异(P0.01)。辽东冷杉幼苗的叶片δ13C与其WUEL在各水分条件下均有良好的正相关关系,而且随着水分胁迫的加剧,δ13C与WUEL的正相关程度也越来越紧密,所以叶片δ13C可以作为筛选高水分利用效率种源的有效指标。      

高CO2浓度对稻田CO2排放影响的初步分析

大气CO2浓度升高显著增加作物生物量,从而使进入土壤的有机碳增加,这势必会影响土壤碳的稳定和积累。此项研究主要通过高CO2浓度对作物生物量的直接影响,利用δ13C技术间接地初步分析土壤呼吸CO2排放不同来源贡献的差异。研究表明,在水稻生长季,高CO2浓度降低田间CO2的排放,但不显著;种有水稻,根系对土壤总的呼吸影响主要体现在成熟期之前,且有相互消长的现象。在种有水稻的情况下抽穗期之前分解新有机质为主;高CO2浓度促进土壤原有有机质的分解,在水稻生长的中后期分解更为明显,且高N水平对老有机质的分解有促进作用。鉴于此项研究中的不足之处,将会不断得到完善。     

Stable Isotope Studies of Crop Carbon and Water Relations： A Review

Crop carbon and water relations research is important in the studies of water saving agriculture, breeding program, and energy and material cycles in soil plant atmosphere continuum （SPAC）. The purpose of this paper is to review the current state of knowledge on stable isotopes of carbon, oxygen, and hydrogen in the research of crop carbon and water relations, such as carbon isotope discrimination （△^13C） during carbon fixation process by photosynthesis, application of △^13C in crop water use efficiency （WUE） and breeding programs, oxygen isotope enrichment during leaf water transpiration, CO2 fixation by photosynthesis and release by respiration, application of hydrogen isotope composition （619） and oxygen isotope composition （6180） for determination of water source used by a crop, stable isotope coupling Keeling plot for investigating the carbon and water flux in ecosystem, energy and material cycle in SPAC and correlative integrative models on stable isotope. These aspects contain most of the stable isotope researches on crop carbon and water relations which have been widely explored internationally while less referred in China. Based on the reviewed literatures, some needs for future research are suggested.     

Large delta¹³C gradients in the preindustrial North Atlantic revealed

The carbon isotopic composition ((13)C/(12)C, expressed as δ(13)C) of fossil foraminifera is the primary tracer used to infer changes in past ocean ventilation, and its variations are interpreted by using the modern oceanic δ(13)C distribution as a framework. However, the present ocean δ(13)C distribution is strongly overprinted by isotopically light anthropogenic carbon dioxide. A correction for this oceanic C-13 Suess effect in the North Atlantic (NA) shows that the pristine NA δ(13)C distribution has a richer and more detailed structure that is more clearly related to water mass distributions. Our results revise some fundamental perceptions regarding glacial-interglacial ocean δ(13)C differences and allow paleo-δ(13)C variations to be understood within the context of modern climate variability.     

Large variations in Southern Hemisphere biomass burning during the last 650 years

We present a 650-year Antarctic ice core record of concentration and isotopic ratios (δ(13)C and δ(18)O) of atmospheric carbon monoxide. Concentrations decreased by ~25% (14 parts per billion by volume) from the mid-1300s to the 1600s then recovered completely by the late 1800s. δ(13)C and δ(18)O decreased by about 2 and 4 per mil (‰), respectively, from the mid-1300s to the 1600s then increased by about 2.5 and 4‰ by the late 1800s. These observations and isotope mass balance model results imply that large variations in the degree of biomass burning in the Southern Hemisphere occurred during the last 650 years, with a decrease by about 50% in the 1600s, an increase of about 100% by the late 1800s, and another decrease by about 70% from the late 1800s to present day.