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1.
Soils contain a diverse and complex set of chemicals and minerals. Being an ‘open system’, both in the chemical and nuclear sense, soils have defied quantitative nuclear dating. However, based on the published studies of the cosmogenic atmospheric 10Be in soils, its relatively long half-life (1.5 Ma), and the fact that 10Be gets quickly incorporated in most soil minerals, this radionuclide appears to be potentially the most useful for soil dating. We therefore studied the natural variations in the specific activities of 10Be with respect to the isotope 9Be in mineral phases in eight profiles of diverse soils from temperate to tropical climatic regimes and evaluated the implications of the data for determining the time of formation of soil minerals, following an earlier suggestion [Lal et al., 1991. Development of cosmogenic nuclear methods for the study of soil erosion and formation rates. Current Sci. 61, 636–639.]. We find that the 10Be/9Be ratios in both bulk soils and in the authigenic mineral phases are confined within a narrower range than in 10Be concentrations. Also, the highest 10Be/9Be ratios in authigenic minerals are observed at the soil-rock interface as predicted by the model. We present model 10Be/9Be ages of the B-horizon and the corresponding soil formation rates for several soil profiles. The present study demonstrates that the 10Be/9Be ratios in the authigenic phases, e.g. clay and Fe-hydroxides, can indeed be used for obtaining useful model ages for soils younger than 10–15 Ma. However, the present work has to be pushed considerably further, to take into account more realistic age models in which, for instance, downward transport 10Be and clays, and in-situ dissolution of clay minerals at depths, altering the 10Be/9Be ratios of the acidic solutions, are included. We show that in the case of younger soils (< 1 Ma) studied here, their 10Be inventories and 10Be/9Be ratios have been significantly disturbed possibly by mixing with transported soils.  相似文献   

2.
It′s essential to measure air concentrations and depositional fluxes of environmental radionuclides in different regions for modeling global contamination transfer and validation, tracing deposition process and dating, referencing watershed erosion trace and assessing natural radiation of ecosystem. This study introduces the research background and methods and explains weekly variations of 210Pb and 7Be concentrations in surface air and precipitation at Mt. Guanfeng/Guiyang since 2001. The results indicate that 210Pb and 7Be concentrations in surface air fluctuate periodically at 2~6 week interval because of the meteorological condition changes. The annual trend in 210Pb air concentration is overall influenced by air temperature variation and periodical rainfall. 7Be air concentration varies up and down regualarly. The synchronization of low concentrations for both 210Pb and 7Be in surface air and high ratio (210Pb/7Be ≥ 0.8) indicate oceanic poor 210Pb-7Be air mass invasion. The synchronization of high concentrations of 210Pb and 7Be in surface air and low ratio (210Pb/7Be ≤ 0.7) implies rich 7Be air mass invasion from altostratus atmosphere. Weekly concentrations of 210Pb and 7Be in precipitation and the Kd coefficients are high in late Autumn to Spring, and low in late Spring to Autumn. Although 210Pb and 7Be concentrations vary seasonally, their weekly concentrations in precipitation increase with that of air concentration. The 210Pb and 7Be weekly concentrations for seasonal division is about 0.2 Bq/L and 1 Bq/L, respectively. However, the Kd coefficient decreases when 210Pb and 7Be air concentrations increase. Deposition of 210Pb and 7Be with precipitation mainly take place in Spring and Summer; The weekly fallout of 210Pb and 7Be increases with increasing precipitation; the increase of 7Be is triple of that of 210Pb and 2.5 when precipitation nears to zero. The weekly-high fallout of 210Pb and 7Be with precipitation corresponds with the dramatic decrease of their air concentrations within or vicinal weeks. The ratio of 210Pb to 7Be in rainfall is overall ≤ 0.5 and varies synchronously with the ratio in surface air, indicating that the two radionuclides are cleaned by precipitation from air at close speed. In the extreme freezing disaster in 2008, both 210Pb and 7Be air concentrations were low and coupling with coexist of low concentration of aerosol and high nuclides activities. Weekly concentration of 7Be in surface air at Mt. Guanfeng demonstrates the anticipated concentration level in the low-latitude and high-elevation region; the short-term fluctuations of 7Be concentration indicated the hysteresis was influcenced by the strong air current submersion and the low-elevation air mass rising differently at Mt. Guanfeng and Mt. Waliguan.   相似文献   

3.
自2001年12月连续逐周在贵阳观风山附近对近地面空气210Pb-7Be浓度和沉降量的观测表明:区域性降水和气温制约近地面空气210Pb具高浓度"U"型年分布;降水量和平流层向下输送影响近地面空气7Be月均浓度的季节性变化;210Pb/7Be月均浓度比率受控于210Pb变化和富7Be气团下沉的影响.观风山与瓦里关山之间因纬度和海拔的关系,7Be比率急剧震荡,显示出海洋性贫7Be气团入侵对观风山地区的明显影响.2002-2008年间贵阳观风山近地面空气210Pb的年均浓度(2.8±0.6)mBq/m3,约为全球若干站点中最高平均浓度值的4倍;而7Be的年均浓度(4.8±0.6)mBq/m3,与全球高海拔站点长期观测的平均值相当,大约为北半球中纬度对流层顶部附近7Be浓度值(18.0 mBq/m3)的1/3.8,显示出低纬度、较高海拔地区的预期水平.2003年,瓦里关山和观风山近地面空气7Be的年均浓度比为3.8,与预期的大气输送和混合作用基本一致.7Be月均浓度的增大趋势反映出受太阳黑子数减少的变化关系,其影响底线大约为4 mBq/m3;7Be年均浓度波动的增大趋势反映出受太阳黑子数降低的可能影响.贵阳观风山降水中7Be和210Pb的体积加权浓度分别为0.72 Bq/L和0.27 Bq/L;年沉降通量分别为0.080 Bq/(cm2·a)和0.031 Bq/(cm2·a).数值模拟显示出全球空气210Pb高浓度区和高沉降通量环带分布,印证了洱海和红枫湖沉积物7Be和157Cs蓄积的模拟结果.  相似文献   

4.
Depth profiles of in situ-produced cosmogenic nuclides, including 10Be (T1/2=1.5×106 years) and 26Al (T1/20.73×106 years), in the upper few meters of the Earth's crust may be used to study surficial processes, quantifying denudation and burial rates and elucidating mechanisms involved in landform evolution and soil formations. In this paper, we discuss the fundamentals of the method and apply it to two lateritic sequences located in African tropical forests.  相似文献   

5.
中国黄土10Be研究进展   总被引：1，自引：0，他引：1  
８０年代中期，中国和瑞士科技工作者开始联合进行黄土＾１０Ｂｅ研究。建立了黄土＾１０ＢｅＡＭＳ测量的理想流程，发现了＾１０Ｂｅ在黄土地层良好保存性等重要地球化学行为特征，确认了黄土＾１０Ｂｅ研究具有重要意义。对洛川黄土部面０．４－１３８ｍ段６００多个样品进行了＾１０Ｂｅ测定，建立了２．５Ｍａ以来大陆堆积物同位素记录曲线。  相似文献   

6.
原地宇宙成因核素(TCN)测年靶标制备   总被引：1，自引：1，他引：0  
自20世纪80年代以来,得益于高能加速器质谱的发展及其分析精度的提高,TCN测年技术得到了快速发展,并被成功应用于解决诸多领域关键性的年代学问题研究中,对地学的发展也起到了革命性的推动作用。TCN测年由测年靶标制备、AMS测量及数据分析等步骤组成。其中测年靶标制备直接影响AMS的测量结果,进而影响可靠年代学框架的建立与古气候环境的重建。测年靶标制备首先是代表性样品的采集,继而是所用靶标矿物的提纯,再者是所测元素的分离提取,最后是靶标压制。此处以第四纪冰川研究中应用较为广泛的TCN放射性核素10Be与26Al为例,结合冰川侵蚀与沉积地貌的分布及其特征,从样品采集、石英提纯、10Be与26Al核素的分离提取及最后的靶标压制等方面展开论述,以期为初涉第四纪冰川研究的学者提供TCN测年靶标制备的理论指导,同时也为地学其他研究领域该测年技术的应用提供参考。  相似文献   

7.
137 Cs示踪技术广泛地应用于农耕地土壤侵蚀研究，目前已建立了许多运用 137 Cs估算土壤侵蚀速率的模型。这些模型主要分为两类：经验模型与理论模型。其中理论模型中的质量平衡模型应用较多。质量平衡模型主要有：Wal l ing模型、张信宝模型、杨浩模型和周维芝模型。重点讨论这 4种质量平衡模型的异同。详细阐述了这四种模型的建立过程，并用图形模拟的方法给出各个模型所刻画的土壤侵蚀速率与土壤剖面中 137 Cs相对损失率的关系。分析表明，尽管各个模型在建立的假设和方法上以及对 137 Cs沉降过程的处理上存在一定程度的差异，但是各个模型所 刻画的土壤侵蚀速率与土壤剖面中 137 Cs相对损失率的关系实质上都是幂函数的形式，而且这 4条曲线的走势基本一致，各自计算的土壤侵蚀速率差异也较小。因此，在利用 137 Cs技术示踪农耕地土壤侵蚀速率时，这 4个模型都可以应用。  相似文献   

8.
塔里木盆地荒漠植物与表土碳同位素组成研究   总被引：2，自引：1，他引：1  
表土有机质碳同位素组成(δ13Corg)反映了来自于地表各种植物δ13Corg的一个混合信息.要从沉积物δ13Corg中提取可靠的植被信息,需要系统研究现代表土有机质δ13Corg与地表植被δ13Corg的差异.初步研究了塔里木盆地主要现代植被及土壤碳同位素组成,对比不同地区土壤和地表植被δ13Corg的差异.结果表明:塔里木盆地柽柳属种群中植物与表土碳同位素组成之间存在显著相关关系,说明在干旱地区土壤中微生物和水生生物等的干扰因素可以忽略,其现代土壤的同位素组成只与地表相应的主要植被类型有关.塔里木盆地柽柳属种群中表土有机质δ13Corg值比地表植被δ13Corg值平均偏正1.71‰左右,不同于其它地区表土和地表植被δ13Corg差异(2.2‰,1‰,0.5‰)的结果,反映不同地区表土和地表植被有机质δ13Corg值差异不同.在利用沉积物δ13Corg值提取古生态植被信息时,应考虑到不同地区土壤有机质与地表植被δ13Corg值的不同差异会影响植被中C3、C4植物组成情况.  相似文献   

9.
Rock samples from the Kanin Peninsula and the Timan Ridge were analysed for in situ cosmogenic 10Be for exposure age dating purposes. Crystalline rocks were sampled at four sites on the Kanin Peninsula, either from bedrock outcrops or from glacial erratics, giving overall similar 10Be ages. Outcropping sandstone and crystalline erratics were available from three sites at the Timan Ridge. The highly weathered sandstone gives substantially younger 10Be ages than the adjacent erratics. The exposure ages from the Kanin Peninsula suggest that the last deglaciation of this area took place between 55 and 37 10Be kyr ago, in agreement with a preceding Kara Sea glaciation (55-45 kyr BP). The northwest coast of the peninsula was probably just outside the maximum limit of the last Scandinavian glaciation (20-17 kyr BP). Glacial erratic exposure ages from the Timan Ridge suggest that the 55-45 kyr BP Kara Sea glaciation reached the northern part of the ridge. The exposure dates do not show conclusive evidence regarding the existence of a Timan Ridge ice cap.  相似文献   

10.
基于改进的CASA模型测算祁连山地区植被净初级生产力（NPP）物质量, 并进一步基于光合作用方程式、 碳循环过程模型估算了研究区2005年、 2010年、 2015年植被、 土壤固碳量及价值, 旨在定量分析该区域不同植被生态系统植被、 土壤固碳价值时空演变情况, 为制定更科学合理的碳管理措施提供科学依据。研究表明： 祁连山地区2005 - 2015年植被、 土壤固碳价值呈递增趋势, 2005年、 2010年、 2015年植被、 土壤固碳价值分别为515.95、 356.56亿元; 491.05、 404.36亿元; 581.55、 465.65亿元, 土地类型的改变使得植被、 土壤固碳分别增长12.72%、 30.39%。从空间分布上看, 东部植被、 土壤固碳量明显高于西部, 林地固碳能力最高, 单位面积固碳量为10.19 t·hm-2。草地是研究区分布最广的植被, 且其对该地区植被、 土壤固碳贡献比为51.13%、 49.34%。  相似文献   

11.
对青藏高原海北站区的自然土壤和扰动土壤进行高分辨率采样,测定土壤根系、有机碳及其14C含量;用14C示踪技术探讨土地利用变化对高寒草甸土壤有机质更新的影响.研究表明,土地利用变化对高寒草甸土壤碳循环影响显著.耕作活动导致扰动土壤有机碳储量比自然土壤增加29.35%;扰动土壤剖面10~50 cm深土壤有机质的14C含量相对富集;自然土壤大多数有机碳储存在土壤表层,更新时间<50 a,同一深度扰动土壤有机碳储量显著少,更新时间长(171~294 a);自然土壤10 cm以下有机碳主要为更新时间>1 000 a的稳定碳所控制,扰动土壤的相应值出现在40 cm以下;自然土壤有机质更新产生的CO2通量为114 gC·m-2·a-1,扰动土壤为48.7 gC·m-2·a-1.  相似文献   

12.
We measured 10Be concentrations in boulders collected from the Orsha and Braslav moraines, associated with the Last Glacial Maximum extent and a recessional stage of the Scandinavian Ice Sheet (SIS), respectively, providing a direct dating of the southeastern sector of the ice-sheet margin in Belarus. By combining these data with selected existing radiocarbon ages, we developed a chronology for the last deglaciation of Belarus. The northeastern part of the country remained ice free until at least 19.2±0.2 cal. kyr BP, whereas the northwestern part of the country was ice free until 22.3±1.5 cal. kyr BP. A lobate ice margin subsequently advanced to its maximum extent and deposited the Orsha Moraine. The ice margin retreated from this moraine at 17.7±2.0 10Be kyr to a position in the northern part of the country, where it deposited the Braslav Moraine. Subsequent ice-margin retreat from that moraine at 13.1±0.5 10Be kyr represented the final deglaciation of Belarus. Direct dating of these moraines better constrains the relation of ice-margin positions in Belarus to those in adjacent countries as well as the SIS response to climate change.  相似文献   

13.
The application of carbon isotope (δ13C) collected from stalagmite to reconstruct the past climate and/or ecologic evolution, relative to other preserved indicators, is much limited due to its complex influencing factors including climate outside cave and complicated and site-specific karstic process. In terms of various climate and non-climate limiting factors on stalagmite δ13C, and combined with a large number of geological records and modern cave monitoring data of the latest researches, the pathway and behavior of the signal transmission of δ13C in the cave system were analyzed. The possible relationship between δ13C excursions and climate oscillations under different time scales was thus discussed. Although the degree of noise becomes increasing mixed with δ13C on centennial scales or shorter, the climatic elements, such as temperature and humidity (or precipitation), as predominant modulators exert directly or indirectly influence on vegetation overlying the soil and associated soil CO2 productivity on millennial-orbital scales. Future work should be focused on further deeply extracting the common δ13C signals from specific caves by exploring the controlling factors, both including climatic and non-climatic ones, attaching importance to the seasonal characteristics of stalagmite δ13C, and taking full advantage of its potential in the indication of local environmental events. The use of multi-proxy and multi-method will contribute to better understanding the interesting linkages among the δ13C characteristics, karstic process, global carbon cycle and associated climate change.  相似文献   

14.
宇宙成因核素~(10)Be揭示的北祁连山侵蚀速率特征   总被引：1，自引：0，他引：1  
山脉侵蚀速率的大小和时空分布信息是研究山脉构造—气候相互作用和地貌演化的关键切入点,其大小是受气候还是构造控制争论已久。宇宙成因核素10Be方法为从千年至万年尺度上定量研究流域平均侵蚀速率提供了一种先进和快捷的技术手段,为揭示侵蚀速率与现代气候和构造地貌因子的关系并进行相关分析提供了基础。利用该方法对北祁连山近现代侵蚀速率进行了研究。所采集的9个流域现代河沙样品,结合前人数据进行共同分析,结果显示该区侵蚀速率的变化范围为18.7~833 mm/ka,北祁连山中段的侵蚀速率约为323 mm/ka,该区侵蚀速率与降雨量没有明显的对应关系,但与流域平均坡度呈现很好的非线性关系,揭示坡度是该区侵蚀速率的最主要控制因素。通过对比北祁连山地表平均侵蚀速率和该区域的断层垂直滑动速率发现整体上该区域地表侵蚀速率要低于祁连山北缘断层的垂直滑动速率,反映了北祁连山正处于地形抬升和生长的过程之中。  相似文献   

15.
末次冰盛期（Last Glacial Maximum, LGM）结束后,全球经历末次冰消期进入全新世,这代表了过去十万年以来最为显著的气候转型事件。末次冰消期的开始在全球范围内近乎同步,但其背后的气候驱动机制仍不明确。中低纬度,如青藏高原及其周边地区的山地冰川对气候变化响应敏感,准确限定LGM结束前后冰川地貌的时代可为上述问题的解决提供可靠的古冰川信息。然而,目前青藏高原仍缺乏足够有针对性的研究。本文选取位于青藏高原东南部的岗日嘎布作为研究区,对该区格泥峰东侧的玉东曲谷口分布的冰碛垄序列进行了详细的地貌调查和宇宙成因核素10Be暴露测年研究。采自玉东曲谷口附近6道冰碛垄中地貌相对年代较老的4道冰碛垄的14个冰川漂砾10Be暴露年龄介于（13.3±1.0）~（19.3±1.4） ka。利用累积概率密度和简化卡方等统计分析方法排除异常值后,将这4道冰碛垄中地貌相对年代较年轻两道的形成时代限定为（17.0±0.5） ka和（18.4±1.0） ka,分别对应末次冰消期和LGM后期。与气候记录进行对比后,我们认为这两次冰川波动响应可能受控于印度洋-太平洋暖池海表温度的夏季气温变化。  相似文献   

16.
Rb作为一个具有中度挥发性、流体活动性、在岩浆过程中呈不相容性的碱金属元素,能为各种地质过程和物质源区提供制约;同时,87Rb是放射性母体,Rb-Sr定年体系在确定长时间尺度的地质体年龄方面也有广泛的应用。传统研究认为特定地质年代下Rb同位素比值(87Rb/85Rb)是一个定值,但随着分离纯化方法的改进和质谱分析精度的提高,高精度Rb同位素组成得以测定,其结果显示,不同地质样品存在明显的Rb同位素组成的差异,意味着地质过程中存在Rb同位素的分馏。Rb同位素分馏能否为示踪Rb的地质过程提供更多有用信息,是否会对传统Rb-Sr定年体系产生影响,这些基础性的问题目前仍然没有答案。要回答这些问题,首先需要了解不同地质储库的Rb同位素组成,发现不同地质过程中的Rb同位素分馏,探讨其发生的控制机制。然而,这方面的研究目前还非常欠缺。文章回顾了近20年来国际上地球科学领域中的Rb同位素已有的研究,包括技术方法、分馏机理等各个方面,在此基础上对其研究前景进行展望,主要包括:(1)总结了Rb同位素组成测定的化学纯化及仪器测量方法,并对其优缺点进行点评,同时指出谨慎的化学前处理方法及质谱测定流程是获得高精度Rb同位素组成结果的基本前提;(2)收集了现有的地外样品Rb同位素组成数据,简述了Rb同位素在宇宙化学中的应用研究成果,指出Rb作为一个中度挥发性元素,对太阳系行星的吸积和演化过程具有重要的指示意义;(3)对Rb同位素在地质过程中潜在广阔的应用前景进行展望,例如完善经典的Rb-Sr定年体系,限定壳幔及地壳内部的分异过程,制约大陆硅酸盐岩风化,以及揭示超大型Rb矿的形成机制。  相似文献   

17.
Li contents and isotopic compositions were determined for a suite of well-characterized basaltic lavas from the Central American Volcanic Arc (CAVA). Variable Li/Y (0.2–0.5), Li/Sc (0.1–0.4), and δ6Li values (+2.6 to −7.7‰) attest to significant compositional heterogeneity in the subarc mantle. Within specific arc segments, these parameters correlate strongly with each other and with a number of other constituents (e.g., K, Rb, Ba, B/La, 10Be/9Be, 87Sr/86Sr, U/Ce, and 230Th/232Th, among others); these correlations are particularly strong for Nicaragua samples. Coupling of this particular set of constituents is best explained in terms of addition of ‘subduction components' to the subarc mantle. Moreover, their selective enrichment with respect to relatively fluid-immobile incompatible elements signifies the dominance of fluid vs. silicate melt transport of slab components to the subarc mantle. Several interesting nuances are revealed by the Li data. First, although Li and B are strongly correlated in both Costa Rica and Nicaragua, there are systematic along-strike variations in Li/B that are consistent with these elements having different ‘fluid release patterns' from subducted slab segments. For example, Li/B is highest in Costa Rica where auxiliary evidence indicates higher subduction zone temperatures; apparently B is preferentially depleted and Li retained in the slab under warmer conditions. The same relations are reflected in Li/10Be and other subduction tracer systematics, all of which point to larger subduction contributions below Nicaragua. Yet, even Nicaragua lavas vary widely in levels of subduction enrichment. High-Ti basalts from Nejapa are the least enriched and have the highest δ6Li (1.4 to 2.6‰); these values are greater than in fresh MORB (ca. −4‰) and are not easily explained by additions of subducted Li because most oceanic crustal rocks and marine sediments have lower δ6Li than MORB (with typical values between −8 and −20‰). Thus, it appears the Nejapa data may be representative of isotopically light mantle domains. Relatively light δ6Li values in an undepleted spinel lherzolite (+11.3‰) from Zabargad Is. (Red Sea) and in primitive backarc basalts (−1.6 to −0.5‰) from Lau Basin support this conclusion. Considering representative fluid and mantle endmember compositions, the CAVA data are consistent with limited (up to a few percent) additions of slab-derived fluids to a heterogeneous mantle containing variably depleted and enriched domains to form the respective magma sources. In our view, the subarc mantle is heterogeneous on a small scale, but some arc sectors clearly received greater slab inputs than others.  相似文献   

18.
地下水-地表水相互作用是水资源管理和地表水生态系统保护中重要的一个环节,氡同位素(222Rn)由于其在地下水与地表水中含量差异显著、性质保守、检测难度低,广泛运用于地下水-地表水相互作用的研究当中。本文通过总结分析222Rn在不同地表水体(海水、河水、湖水等)中的应用,指出刻画地下水氡浓度的异质性是估算地下水排泄的重点和难点。在估算海底地下水排泄(SGD)时,氡的混合损失项估算不确定、海水氡浓度时空变异性、SGD的多组分特征等可能给估算结果带来较大不确定性;在估算河流地下水排泄时难以确定氡的大气逃逸量;研究人员对氡在示踪地表水补给地下水方面的研究程度相对不足。本文从科学研究和实际生产方面,对222Rn的研究应用提出以下潜在方向:(1)降低地下水氡空间变异性对估算地下水排泄量的影响;(2)针对不同水体、不同水文条件,准确刻画氡的大气逃逸量;(3)拓展222Rn示踪能够解决的科学问题;(4)将氡质量平衡模型计算与不确定分析相结合,实现软件化。  相似文献   

19.
红壤丘陵区地表水资源动态与合理调蓄利用研究   总被引：9，自引：0，他引：9       下载免费PDF全文
以红壤丘陵景观中相对独立且整体性强的集水区为基本单元,重点研究了集水区内降水、蒸散、水量蓄存等地表水资源的年变化。结果表明,降水资源在集水区内的陆面拦截蒸散、塘堰蓄存、排出集水区三者中的分布比例约为7:2:1,在水土保持型坡地的植被拦截、土壤渗流、地表径流三者中的分布比例约为3:5:2;每公顷1m土体中的土壤贮水量,在丰水季节,水土保持型坡地要比非水保坡地高出864.0～1067.0m3,少水季节则高出647.0～855.0m3。研究结果还表明,以集水区为单元的农业灌溉用水量,一般为年降水量的12%左右,蓄存此水量的塘堰面积应占集水区土地总面积的11%左右,对于塘堰面积已占土地总面积10%左右的红壤丘陵区而言,抗御季节性干旱依靠扩大塘堰蓄水已不现实,其主要途径应是充分发挥水库工程和"土壤水库"的巨大抗旱潜力。  相似文献   

20.
土壤碳动力学同位素示踪研究进展   总被引：1，自引：1，他引：0  
土壤是陆地生态系统中最大的碳库。土壤碳动力学旨在研究土壤有机碳库的大小及更新速率。土壤有机碳库可分为 3个亚碳库："活动"、"缓慢"和"稳定"碳库。碳同位素特别是 14 C可作为研究土壤碳动力学的理想示踪剂;δ 13 C值是定量研究C3和C4植被更替历史的有效手段; 14 C示踪及年代测定与 13 C信号联合使用,可以估算土壤碳库的大小和驻留时间。碳同位素示踪应用于土壤碳动力学研究取得了较大进展,但是由于缺乏可靠的全球数据库和标准方法来量化土壤有机碳库,导致对土壤各亚碳库的大小和更新速率以及土壤CO2的估算仍存在较大的不确定性,从而难以估计土壤碳库大小的变化对大气CO 2浓度和全球气候变化的潜在贡献。  相似文献   

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