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在极端气候事件频发和人类活动加剧的背景下,抚仙湖水位波动显著,尤其是2009—2012年极端干旱事件的发生,使抚仙湖平均水位（1721.31 m）低于法定最低水位（1721.65 m）,给生态环境安全带来严重威胁.因此,找到合适有效的湖泊水位模拟方法,对气候变化影响下的未来水位进行预测,并做好相应的应对准备,对湖泊生态系统的保护至关重要.本文运用DYRESM水动力模型对抚仙湖1959—2050年水位进行了模拟.因抚仙湖流域尚无长时间序列的历史水文观测数据,故利用模型和水量补偿法对抚仙湖入湖水量进行反推,构建了降水量-入湖水量的回归方程,并通过有效的实测入湖水量和水位数据,对回归方程的精度进行了检验.利用全球气候模式BCC-CSM2-MR中SSP245和SSP585两种情景提供的未来气候预估数据,运用DYRESM预测了抚仙湖2021—2050年水位变化趋势.结果表明：（1）构建的DYRESM水动力模型和降水-入湖水量回归方程精度较高,模型结果能很好地反映抚仙湖水位的年际和年内变化趋势,且能有效捕捉到抚仙湖的水位峰值.（2）在SSP245和SSP585两种情景下,抚仙湖2021—2050年多年平均水位分别为1722.98和1723.93 m,较1959—2017年平均水位1721.77 m分别升高1.21和2.16 m.两种情景下抚仙湖未来水位均有部分时段超过法定最高蓄水位（1723.35 m）,但均高于法定最低水位.因此,未来气候变化对抚仙湖水量的影响有限,并不会导致水位过低,当水位超过法定最高蓄水位时,可通过控制出流闸门将水位调节在合理范围内. 相似文献
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SWH双源蒸散模型模拟效果验证及不确定性分析 总被引：1，自引：0，他引：1
SWH模型是在经典Shuttleworth-Wallace双源蒸散模型的基础上发展起来的蒸散模型。过去的研究结果表明在站点尺度上SWH模型表现出较高模拟精度,但有关模型对主要参数及驱动变量的敏感性以及模型模拟的不确定性来源等缺乏深入理解与认识。本文通过与51个陆地生态系统站点多年的蒸散观测数据对比,在季尺度、年尺度上验证了全国范围内SWH模型的模拟效果,并分析了关键参数和驱动变量对模型不确定性的贡献大小。结果表明：SWH模型在区域尺度上取得了较好的模拟效果,模拟蒸散与实测值R2均在0.75以上。模型各参数中,冠层导度估算涉及的两个参数对蒸散模拟不确定性影响较大;驱动数据中,归一化植被指数对蒸散模拟不确定性影响较大。尽管部分数据（如降水）因插补存在较大的误差,但总体上气候驱动数据对蒸散模拟的不确定性的贡献仍低于NDVI。 相似文献
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洞庭湖流域下落雨滴蒸发研究 总被引：1，自引：1，他引：0
通过在亚热带季风区内的洞庭湖流域对降水事件取样以及气象资料的收集,采用降水同位素对流域下落雨滴蒸发以及影响因素进行了研究。研究发现：流域不同季节大气水线的理论斜率均高于观测斜率,由此可判断形成流域降水的雨滴在下落过程中经历了不同程度的蒸发。进一步计算表明流域下落雨滴的蒸发比率介于0.21%~19.29%之间,蒸发比每增大1.0%,过量氘（d）将减小1.38‰。从主要影响下落雨滴蒸发的气温、湿度和雨滴直径来看,流域下落雨滴蒸发与气温呈显著正相关,与相对湿度、雨滴直径呈显著负相关。另外,流域下落雨滴蒸发随降水量增大呈指数函数递减,其并非指示降水量直接影响雨滴的蒸发,而是湿度、雨滴直径等综合作用的结果。 相似文献
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The newly discovered large-scale Baiganhu W–Sn orefield, consisting of the Kekekaerde, Baiganhu, Bashierxi, and Awaer deposits, is located in Ruoqiang County, southeastern Xinjiang, China. These deposits comprise mainly three types of W–Sn mineralization: early-stage skarn-type, middle-stage greisen-type, and late-stage quartz-vein-type. In this study, we classified seven major vertical zones on the basis of petrographic characteristics, roughly from the bottom of the parental granitic intrusions upward, as (A) fresh syenogranite, (B) argillic alteration, (C) muscovite-dominated greisenization, (D) tourmaline-dominated greisenization, (E) marginal facies (including K-feldspar pegmatite and fine-grained granite), (F) aplitic apophysis, and (G1) skarn or (G2) infilled silification zones. According to the alteration–mineralization assemblages and cross-cutting relationships, five stages of mineralization are recognized in the orefield (I, skarn stage; II, greisen stage; III, quartz vein stage; IV, argillic alteration stage; and V, supergene stage), and reverse alteration zonation in the altered intrusion is also observed.The W–Sn deposits are spatially associated with syenogranite, which is part of the Caledonian Bashierxi magmatic series. Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) zircon U–Pb dating of the syenogranite yields a weighted mean 206Pb/238U age of 413.6 ± 2.4 Ma (MSWD = 0.36, n = 30). Hydrothermal muscovite from three samples associated with W–Sn mineralization yields plateau 40Ar/39Ar ages of 411.7 ± 2.6 Ma (MSWD = 0.21), 412.8 ± 2.4 Ma (MSWD = 0.22), and 413.8 ± 2.6 Ma (MSWD = 0.22), which is consistent with the zircon U–Pb age, thus indicating a temporal link between the emplacement of the syenogranite and the W–Sn mineralization. Our age data and previously published ages, along with geochemical data, for the granitoids in the Bashierxi magmatic series show a nearly contemporaneous evolution of A- and S-type granites, which were emplaced in a post-orogenic setting at ca. 432–413 Ma. As compared with the A-type granites, the syenogranites with S-type affinities probably resulted from a lower degree of partial melting of metagreywackes, which was more likely to be enriched in the ore-forming elements W and Sn, as well as volatiles such as B and H2O. In addition, the syenogranites exhibit low oxidation states and underwent high degrees of factional crystallization, both of which favor post-magmatic W–Sn mineralization. We suggest that more attention should be given to buried syenogranites of S-type affinities during mineral exploration in this area, and that the proposed model of a vertical alteration zoning can act as a guide to the targeting of similar ore systems. 相似文献
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Analyzing Yengisogat Glacier surface velocities with ALOS PALSAR data feature tracking, Karakoram, China 总被引：1，自引：1，他引：0
Zong-li Jiang Shi-yin Liu Juliane Peters Jian Lin Si-chun Long Yong-shun Han Xin Wang 《Environmental Earth Sciences》2012,67(4):1033-1043
Little is known about the detailed behavior of glaciers in the Karakoram Mountains. Advanced land observing satellite (ALOS) phased array type L-band synthetic aperture radar (PALSAR) data were used to obtain the surface velocity of the Yengisogat Glacier in the Karakoram Mountains. Four ALOS PALSAR data sets with 46?days temporal baseline acquired from 2007 to 2009 covered all four seasons and were used to extract the offset fields and estimate annual average surface velocity based on seasonal velocities. For the ALOS PALSAR data the synthetic aperture radar (SAR) feature-tracking procedures within the GAMMA software were utilized instead of SAR interferometry because of low coherence in case of fast-moving glaciers or large time intervals between the image acquisitions. The accuracy of the measurements is discussed, and the measurements were consistent with previous results from optical imagery feature tracking. It was revealed that the south tributaries contributed to the main flow of the glacier, with the glacier surface velocities of the south tributaries moving more rapidly than the north tributaries. This was mainly attributed to the effect of the glacier??s aspect in the glacier long-term development point of view. Seasonal and spatial variations of the glacier surface velocity imply that the tributary South Skamri Glacier is probably surging. This has previously been mentioned by some researchers such as Copland et al. The Equilibrium Line Altitude was found to be at about 5,000?m a.s.l for south tributaries, estimated from the surface velocity distribution along the glacier centerline. 相似文献
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Panxian Dadong Cave located in the western Guizhou is a very important Paleolithic site in China. At this site bone and stone artifacts, human teeth and mammalian fossils (known as Ailuropoda-Stegodon fauna) were found, and the site was previously dated to 120–300 ka using ESR/uranium-series methods. In this study, we successfully extracted fine quartz grains from flowstone and silty carbonate-rich sediments in the excavated area. The quartz extracts displayed excellent luminescence properties, and satisfied the SAR (single-aliquot regenerative dose method) acceptance criteria. The sensitivity-corrected OSL signals are not saturated at a dose up to about 1400 Gy. The cultural unit was OSL dated to 190–300 ka, corresponding to MISs 7–8. The flowstone deposits overlying the cultural unit were determined to be 13–190 ka and the silty carbonate-rich sediments underlying the cultural unit to be 300–360 ka. The optical ages are in general agreement with the coupled ESR/U-series and U-series ages. 相似文献
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Multi-episodic (three episodes at least) hydrothermal silica chimneys are identified in the black chert successions (up to ～ 100 m thick locally), overlain by thick black shales (up to a few 100 m thick), in the Ediacaran–Cambrian boundary successions along the southern marginal zone of the Yangtze Platform, South China. Their occurrences are constrained within the lowermost Cambrian by the SHRIMP U–Pb zircon dating and stable isotopic chemostratigaphic data, and are stratigraphically coincident with the negative isotopic excursions of organic carbon (～ 10‰ VPDB in magnitude) and sulfide sulfur (between 0 and 10‰ CDT), i.e., in bases of Nemakit–Daldynian and Tommotian stages in the Lower Cambrian. In this case, a causal link could have existed between which the hydrothermal venting could have released huge amounts of reduced silica-rich hydrothermal fluids with abundant 13C-depleted greenhouse gases (methane) and volcanic-originated H2S into the ocean and/or atmosphere, resulting in an extreme warm climate and oceanic anoxia, oceanic chemical perturbation, and subsequent massive precipitation of silica (chert), and large-magnitude negative isotopic excursions of organic carbon and sulfide sulfur. This scenario provides a unique chance to explore the causes of apparent tectono-depositional, oceanic and geochemical perturbations during this critical interval in South China and elsewhere. 相似文献
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Thermal stability of soil organic carbon subjected to water erosion as a function of edaphic factors
Zhongwu Li Linhui Xiao Chuxiong Deng Zaijian Yuan Chen Liang Qian Xiong Zeting Li Xiaodong Nie 《国际泥沙研究》2022,37(1):26-36
The stability of soil organic carbon （SOC）,as it relates to resistance to decomposition,is important for greenhouse gas emission and climate change.However,the SOC stabilization and its related influencing factors subjected to water erosion remain uncertain.The objective of the current study was to determine the SOC stability under long-term water erosion and to investigate the link between SOC stability and edaphic factors.Soil samples from eroded,depositional,and control sites in a closed wate... 相似文献