We present a record on carbon stable isotopic composition (δ 13C), covering 75 through 10 thousands years ago (ka B.P.), from Hulu Cave, Nanjing. The overlapping δ 13C pro-files are very similar in pattern and range...We present a record on carbon stable isotopic composition (δ 13C), covering 75 through 10 thousands years ago (ka B.P.), from Hulu Cave, Nanjing. The overlapping δ 13C pro-files are very similar in pattern and range, indicating that they mainly record climatic signal. Dur-ing the last glacial-interglacial transition, the >6‰ change of δ 13C values implies different con-tributions of C3 vs. C4 type plants in soils. On millennial scale, however, the increased calcite δ 13C during the warm Dansgaard-Oeschger (DO) events suggests a decrease of dissolved bio-genic CO2 when water flux rate through soil is large. This correlation between heavier δ 13C and higher precipitation is consistent with our previous report on the samples’ stable oxygen isotope records (Wang et al., 2001). Comparison of coeval δ 13C and δ 18O of stalagmites indicates that kinetic fractionation of carbon isotope is closely related to growth rate of stalagmites. This study also shows that local vegetation changes may lag behind precipitation changes by ~700 years during the deglaciation.展开更多
By using a single-year discrimination chronology detrended from a δ13C chronology from Chinese pine (Pinus tabulaeformis) tree rings and meteorological data, the δ13C-climatic response is analyzed. The results show ...By using a single-year discrimination chronology detrended from a δ13C chronology from Chinese pine (Pinus tabulaeformis) tree rings and meteorological data, the δ13C-climatic response is analyzed. The results show that high-frequency δ13C is significantly related to both temperatures of June (with r=-0.65) and the total precipitation of May, June and July (r=-0.46). This suggests that δ13C records reflects some features of the East Asian summer monsoon. In addition, temperature departure for June is reconstructed from a transfer function developed with δ13C-climatic response.展开更多
该文建立液相色谱-稳定同位素比值质谱联用(liquid chromatography-stable isotope ratio mass spectrometry,LC-IRMS)检测抗坏血酸δ^(13)C值的分析方法,用于鉴别针叶樱桃粉中抗坏血酸天然来源的真实性。样品中抗坏血酸经液相色谱在线...该文建立液相色谱-稳定同位素比值质谱联用(liquid chromatography-stable isotope ratio mass spectrometry,LC-IRMS)检测抗坏血酸δ^(13)C值的分析方法,用于鉴别针叶樱桃粉中抗坏血酸天然来源的真实性。样品中抗坏血酸经液相色谱在线分离纯化,优化后色谱条件为:Syncronis C18(250 mm×4.6 mm,5μm)色谱柱,流动相为水-pH 2的硫酸溶液(90∶10,体积比),流速0.250 mL/min,色谱柱温度30℃,进样量10μL,通过LC-IsoLink实现目标物全部氧化为CO_(2)气体,最终以气态形式进入稳定同位素质谱仪,直接检测样品中抗坏血酸的δ^(13)C,该方法结果稳定、准确。分别测定了7个合成来源的维生素C片和19个针叶樱桃粉,结果表明,天然来源抗坏血酸δ^(13)C值为-25.00‰~-22.01‰,合成来源抗坏血酸δ^(13)C值为-11.74‰~-10.28‰,两者分布显著性差异,该方法可用于抗坏血酸产品标识的真实性鉴别研究。展开更多
文摘We present a record on carbon stable isotopic composition (δ 13C), covering 75 through 10 thousands years ago (ka B.P.), from Hulu Cave, Nanjing. The overlapping δ 13C pro-files are very similar in pattern and range, indicating that they mainly record climatic signal. Dur-ing the last glacial-interglacial transition, the >6‰ change of δ 13C values implies different con-tributions of C3 vs. C4 type plants in soils. On millennial scale, however, the increased calcite δ 13C during the warm Dansgaard-Oeschger (DO) events suggests a decrease of dissolved bio-genic CO2 when water flux rate through soil is large. This correlation between heavier δ 13C and higher precipitation is consistent with our previous report on the samples’ stable oxygen isotope records (Wang et al., 2001). Comparison of coeval δ 13C and δ 18O of stalagmites indicates that kinetic fractionation of carbon isotope is closely related to growth rate of stalagmites. This study also shows that local vegetation changes may lag behind precipitation changes by ~700 years during the deglaciation.
文摘长身高原鳅(Triplophysa tenuis)对维持木扎提河的水生态系统物质和能量流动具有重要作用。文章基于脂肪酸生物标记法和碳、氮稳定同位素(δ^(13)C、δ^(15)N)技术研究了长身高原鳅的食性和营养生态位特征。结果显示,其肌肉中共检测出22种脂肪酸,其中有8种饱和脂肪酸、6种单不饱和脂肪酸、8种多不饱和脂肪酸;由特征脂肪酸组成情况推测,长身高原鳅对浮游动物、硅藻、陆地植物或喜摄食硅藻的鱼虾均有摄食,表现为杂食性。长身高原鳅的δ^(13)C和δ^(15)N分别介于-27.09‰~-20.98‰和5.71‰~8.45‰,营养级介于2.68~3.48。雌雄样本间的δ^(13)C、δ^(15)N和营养级均不存在显著性差异(P>0.05);雄性样本核心生态位(Standard ellipse area,SEAc)和总生态位(Total area of convex hull,TA)均高于雌性。δ^(13)C与体长间表现为极显著正相关性(P<0.01),δ^(15)N和营养级与体长间不具有显著相关性。70~80 mm体长组与90 mm以上体长组SEAc面积不存在重叠且在聚类分析中被分为不同组。综上,长身高原鳅的食性为杂食性且食物组成随体长变化而不同,作为营养级偏高的捕食者,长身高原鳅能延长食物链长度,增加食物网复杂性,有利于维持水域生态系统的稳定性。
基金Project supported by the National Natural Science Foundation of China and US National Oceanic and Atmospheric Administration.
文摘By using a single-year discrimination chronology detrended from a δ13C chronology from Chinese pine (Pinus tabulaeformis) tree rings and meteorological data, the δ13C-climatic response is analyzed. The results show that high-frequency δ13C is significantly related to both temperatures of June (with r=-0.65) and the total precipitation of May, June and July (r=-0.46). This suggests that δ13C records reflects some features of the East Asian summer monsoon. In addition, temperature departure for June is reconstructed from a transfer function developed with δ13C-climatic response.
