CAJ | 학술논문

利用稳定同位素技术和Keeling Plot方法可以有效分割地表蒸散量,进而加深对陆地生态系统水循环的理解.该研究通过原位连续测定麦田的水汽同位素数据,评价Keeling Plot方法在分割地表蒸散中的应用,并揭示华北冬小麦(Triticum aes-tivum)蒸腾在总蒸散中的比例.实验于2008年3-5月在中国科学院栾城农业生态站进行,利用国际上先进的H_2~(18)O、HD~(16)O激光痕量气体分析仪(TDLAS)为基础构建的大气水汽~(18)O/~(16)O和D/H同位素比原位连续观测系统,同时利用涡度相关技术、真空抽提技术、同位素质谱仪技术,获取了必要的数据.研究分析了一天中不同时间段的连续的大气水汽δ~(18)O与水汽浓度倒数拟合Keeling Plot曲线的差异和可能的原因.结果显示,中午时段的拟合结果较好,这也暗示中午时段蒸腾速率高时最可能满足植物蒸腾的同位素稳定态假设.进一步的分析发现植物蒸腾的同位素稳定态并不总是成立,尤其是水分胁迫下进入成熟期的小麦,其蒸腾水汽同位素一般处于非稳定态.利用同位素分割结果显示,生长盛期麦田94%-99%的蒸散来源于植物蒸腾.
이용은정동위소기술화Keeling Plot방법가이유효분할지표증산량,진이가심대륙지생태계통수순배적리해.해연구통과원위련속측정맥전적수기동위소수거,평개Keeling Plot방법재분할지표증산중적응용,병게시화북동소맥(Triticum aes-tivum)증등재총증산중적비례.실험우2008년3-5월재중국과학원란성농업생태참진행,이용국제상선진적H_2~(18)O、HD~(16)O격광흔량기체분석의(TDLAS)위기출구건적대기수기~(18)O/~(16)O화D/H동위소비원위련속관측계통,동시이용와도상관기술、진공추제기술、동위소질보의기술,획취료필요적수거.연구분석료일천중불동시간단적련속적대기수기δ~(18)O여수기농도도수의합Keeling Plot곡선적차이화가능적원인.결과현시,중오시단적의합결과교호,저야암시중오시단증등속솔고시최가능만족식물증등적동위소은정태가설.진일보적분석발현식물증등적동위소은정태병불총시성립,우기시수분협박하진입성숙기적소맥,기증등수기동위소일반처우비은정태.이용동위소분할결과현시,생장성기맥전94%-99%적증산래원우식물증등.
Aims Stable isotopes technique and Keeling Plot relationship offer great promise for partitioning evapotranspi-ration (ET), which can help us better understand the hydrologic cycle within terrestrial ecosystems. Our objectives are to evaluate the Keeling Plot method in ET partitioning using in situ continuous δ~(18)O data and fred the frac-tional contribution of crop transpiration to total ET in a winter wheat (Triticum aestivum)field.Methods Field experiments were conducted at Luancheng Agro-ecology Station, Chinese Academy of Sciences. A hydrogen and oxygen isotopes in situ measurement system based on Tunable Diode Laser Absorption Spectros-copy (TDLAS)was used to obtain the continuous atmospheric vapor δ~(18)SO data. Other measurements were made with the eddy covariance technique, cryogenic vacuum distillation and stable isotope ratio mass spectrometry. Important findings An analysis on the Keeling Plot relationships based on data from different time intervals in one daytime showed that the Keeling Plot would be better when using the midday time interval data to build Keeling Plot, which inferred that the plant transpiration isotopic steady-state (ISS)can be more easily obtained during midday when plant transpiration flux is generally largest. ISS was not always satisfied in field conditions, especially when mature wheat suffered from water stress. Using isotopic partitioning, we estimated transpiration contributed roughly 94%-99% to the total ET during the field measurement period, which indicated plant transpi-ration dominated local ET.