高亚洲定位监测冰川平衡线高度时空分布特征研究

利用高亚洲定位监测冰川平衡线高度数据,对平衡线高度时空分布特征进行了分析。结果表明：高亚洲冰川平衡线高度在空间尺度上具有纬度地带性、经向地带性和区域性的特征。在时间尺度上,高亚洲定位监测冰川平衡线高度呈现不同程度的升高趋势。在天山山区,乌鲁木齐河源1号冰川和Ts.Tuyuksuyskiy冰川的平衡线高度在1960-2013年间,分别增加约116m、80m,二者相比,Ts.Tuyuksuyskiy冰川对气候变化的敏感性更高;在阿尔泰山区,No.125（Vodopadniy）冰川、Maliy Aktru冰川和Leviy Aktru冰川在1983-2007年间,平衡线高度变化趋势基本一致,总体都呈升高趋势,其中,Maliy Aktru冰川平衡线高度增幅最大,升高了约142m;高亚洲定位监测冰川中,1962-2008年间,七一冰川平衡线高度升高速度最快,增幅最大,升高了约264m,升高速度最为缓慢的是乌鲁木齐河源1号冰川,其增幅最小,升高了约47m。     

Geomorphic influence on small glacier response to post‐Little Ice Age climate warming: Julian Alps,Europe

The evolution of glaciers and ice patches, as well as the equilibrium‐line altitude (ELA) since the Little Ice Age (LIA) maximum were investigated in the Julian Alps (south‐eastern European Alps) including ice masses that were previously unreported. Twenty‐three permanent firn and ice bodies have been recognized in the 1853 km² of this alpine sector, covering a total area in 2012 of 0.385 km², about one‐fifth of the area covered during the LIA (2.350 km²). These features were classified as very small glaciers, glacierets or ice patches, with major contribution to the mass balance from avalanches and wind‐blown snow. Localized snow accumulation is also enhanced in the area due to the irregular karst topography. The ice masses in the region are at the lowest elevations of any glaciers in the Alpine Chain, and are characterized by low dynamics. The ELAs of the two major LIA glaciers (Canin and Triglav) have been established at 2275 ± 10 m and 2486 ± 10 m, respectively, by considering the reconstructed area and digital elevation model (DEM) and using an accumulation area ratio (AAR) of 0.44 ± 0.07, typical of small cirque glaciers. Changes in the ELA and glaciers extension indicate a decoupling from climate. This is most evident in the smallest avalanche‐dominated ice bodies, which are currently controlled mainly by precipitation. The damming effect of moraine ridges and pronival ramparts at the snout of small ice bodies in the Julian Alps represents a further geomorphological control on the evolution of such ice masses, which seem to be resilient to recent climate warming instead of rapidly disappearing as should be expected. Copyright © 2016 John Wiley & Sons, Ltd.     

雅鲁藏布江中游杰德秀古湖的发现及其意义

在雅鲁藏布江中游山南宽谷段发现了一套湖相沉积地层,形成时代为晚更新世晚期,为冰川阻江形成的堰塞湖沉积物。野外调查发现该套湖相地层在桑日县、乃东县、扎囊县等地均有出露,综合研究认为其为一个东起桑日县扎巴村、西至贡嘎机场附近的大型古堰塞湖泊,面积达700多km2。通过区域调查,该堰塞湖形成的湖相沉积地层在贡嘎县杰德秀镇出露最厚,厚10余m,主要由粉砂质黏土层、细砂层组成,水平纹层等湖相沉积特征明显,本研究称之为杰德秀古湖。杰德秀剖面顶部14C日历校正年龄为15 680～15 105 aBP,属于末次盛冰期。对比林芝古湖、格嘎古湖和松宗古湖等雅鲁藏布江下游堰塞湖的沉积物特征和形成时间,认为杰德秀古湖发育于末次盛冰期。沉积相特征和湖水库容量模拟分析表明,该堰塞湖发育时期,雅鲁藏布江中游山南宽谷段并未完全封闭,为一个湖水面积巨大的过水湖或吞吐湖,类似于现代过水水库。桑日县扎巴村雅鲁藏布江河谷两岸分布有冰碛物,其与雅鲁藏布江中游山南宽谷段的湖相沉积地层的时空关系指示杰德秀古湖与冰川阻塞河道有关,杰德秀古湖是由于冰川阻江形成的冰川堰塞湖。研究结果也进一步说明,雅鲁藏布江现代水系形成以前,其中游不存在面积巨大的众多古湖泊,雅鲁藏布江也不是溯源侵蚀疏干多个古湖泊而形成的,在古湖泊形成之前,雅鲁藏布江已经贯通。雅鲁藏布江流域内的古湖泊是由于气候变化、新构造运动或地震活动等原因造成河道堵塞形成的堰塞湖。     

长白山现代理论雪线和古雪线高度

According to the glacial landforms and deposits with the optically stimulated luminescence (OSL) dating results, two glacial stages of the last glacial cycle (LGC) and Late Glacial were identified. The Late Glacial stage (Meteorological Station glacier advance) took place about 11 ka (11.3±1.2 ka), and the last glacial maximum (LGM), named Black Wind Mouth glacier advance, occurred at 20 ka (20.0±2.1 ka). Based on the Ohmura’s formula in which there is a relationship between summer (JJA) atmospheric temperature (T) and the annual precipitation (P) at ELA, the present theoretical equilibrium line altitude (ELA_t) in Changbai Mountains was 3380±100 m. Six methods of accumulation-area ratio (AAR), maximum elevation of lateral moraines (MELM), toe-to headwall altitude ratios (THAR), the terminal to summit altitudinal (TSAM), the altitude of cirque floor (CF), and the terminal to average elevation of the catchment area (Hofer) were used for calculation of the former ELAs in different stages. These methods provided the ELA for a range of 2250–2383 m with an average value of 2320±20 m during the LGM, which is 200 m higher than the value of previous investigation. The snowlines during the Late Glacial are 2490 m on northern slope, and 2440 m on western slope. The results show that the snowline on northern slope is 50 m higher than that on western slope during the Late Glacial, and the average snowline is 2465m. The ΔELA values were more than 1000 m during the LGM, and about 920 m lower than now during the Late Glacial stage respectively. Compared with Taiwanese and Japanese mountains in East Asia during the LGM, the effect of the uplift on ELA in Changbai Mountains during the glaciations (i.e. 20 m uplift in the LGM and 11 m in the Late Glacial) is not obvious. Foundation: National Natural Science Foundation of China, No.40571016 Author: Zhang Wei (1969–), Ph.D and Professor, specialized in Quaternary environment and climate geomorphology.     

南四湖地区水环境问题探析

末次盛冰期（ＬＧＭ）是太阳辐射异常处于极低值,北半球第四纪冰流规模处于峰值,两万年来距人类环境最近但与现代气候有着巨大反差的特殊时期,７０年代以来由于新资料不断积累,气候模拟技术发展,海洋大陆冰流各圈层的相关和偶合,传统的气候指标和新的气候指标的认识和应用,以及区域性和全球性的国际合作,在ＬＧＭ古气候环境领域已经取得了巨大进展,本文根据数个国际ＬＧＭ合作计划研究成果,综述９０年代以来全球对ＬＧＭ研     

A preliminary estimate of changing calcrete carbon storage on land since the Last Glacial Maximum

The glacial-to-interglacial shift in land carbon storage is important in understanding the global carbon cycle and history of the climate system. While organic carbon storage on land appears to have been much less than present during the cold, dry glacial maximum, calcrete (soil carbonate) carbon storage would have been greater. Here we attempt a global estimation of this change; we use published figures for present soil carbonate by biome to estimate changing global soil carbonate storage, on the basis of reconstruction of vegetation areas for four timeslices since the Last Glacial Maximum. It appears that there would most likely have been around a 30–45% decrease in calcrete carbon on land accompanying the transition between glacial and interglacial conditions. This represents a change of about 500–400 GtC (outer error limits are estimated at 750–200 GtC) . In order to be weathered into dissolved bicarbonate, this would take up an additional 500–400 GtC (750–200 GtC) in CO₂ from ocean/atmosphere sources. An equivalent amount to the carbonate leaving the caliche reservoir on land may have accumulated in coral reefs and other calcareous marine sediments during the Holocene, liberating an equimolar quantity of CO₂ back into the ocean-atmosphere system as the bicarbonate ion breaks up.     

末次盛冰期以来西沙海槽天然气水合物储库变化及其对环境的影响

利用Milkov和Sassen的模型计算了目前及末次盛冰期时西沙海槽天然气水合物的稳定带(GHSZ) 厚度及资源量, 讨论了末次盛冰期以来海洋底水温度增加和海平面升高对西沙海槽天然气水合物储库变化的影响.计算结果表明, 底水温度增加使GHSZ厚度减薄, 资源量减少; 而海平面上升使GHSZ厚度增加, 资源量增加, 但底水温度变化对GHSZ厚度和资源量的影响比海平面变化的影响更大.西沙海槽末次盛冰期时GHSZ平均厚度约为299m, 天然气水合物资源量约为2.87×1010m3, 甲烷数量约为4.71×1012m3; 目前的GHSZ平均厚度约为287m, 天然气水合物资源量约为2.76×1010m3, 甲烷数量约为4.52×1012m3.由此可见, 自末次盛冰期以来西沙海槽的GHSZ平均厚度减薄了~12m, 大约1.1×109m3的天然气水合物分解释放了1.9×1011m3的甲烷, 这些甲烷可能对环境产生了重要影响.      

Revisiting the palaeoenvironmental and climatic history of the Cherangani Hills using fungal spores

Fungi are highly sensitive to environmental and climatic changes. Palaeoecological reconstructions utilising tropical African fungal spores, however, are rare and patchy. Here, we show that fossil fungal spores preserved in core KAP-01 from the Cherangani Hills in Kenya tracks critical environmental changes in the African tropics since the Last Glacial Maximum (LGM), largely synchronous with observations in the pollen record from the same site. Consistent with the pollen record, the presence of fungal taxa in the record, albeit meagre, during the LGM point to an intermittent wetter Cherangani that allowed for the presence of the observed taxa and the prevalence of cool, dry conditions during the last deglaciation. The elevated fungal spore activity during the Late Holocene is evidence for warm, moist environmental conditions and broadly consistent with the pollen record. These different fungal spore taxa, which can be employed to track distinct environmental conditions and processes, provide a dimension that can be overlooked if the reconstruction of the palaeoenvironment were to rely solely on pollen. Thus the fungal spore record enables us to affirm the interpretation of the prevalence of warm, moist conditions evident from such as the Holocene pollen record.     

Mass balance sensitivity to climate change: A case study of glacier No. 1 at urumqi riverhead, Tianshan Mountains, China

Ｓｔｕｄｉｅｓｓｈｏｗｔｈａｔｔｈｅｇｌｏｂａｌｓｕｒｆａｃｅｔｅｍｐｅｒａｔｕｒｅｗｉｌｒｉｓｅａｔａｒａｔｅｏｆ０．３℃ｐｅｒ１０ａｉｎｔｈｅｎｅｘｔｓｅｖｅｒａｌｄｅｃａｄｅｓ（Ｈｏｕｇｈｔｏｎｅｔａｌ．,１９９０,１９９２;Ｓｈｉ,１９９５;...     

基于浮游有孔虫Mg/Ca温度重建的末次盛冰期以来北欧海次表层温度的变化

对我国第五次北极科考在北欧海所采集的两根岩芯样品进行了冰筏碎屑(Ice-Rafted Debris,IRD)丰度、AMS 14C测年、有孔虫丰度统计、浮游有孔虫Neogloboquadrina pachyderma(sin.)(Nps)稳定氧碳同位素及其Mg/Ca重建的次表层海水古温度等指标分析,建立了20ka以来的年代框架。结果表明,在末次盛冰期(20.0~17.5kaBP),次表层温度整体较低(~3℃),钙质生产力下降,冰筏碎屑输入增加;在冰消期(17.5~11.7kaBP)的Heinrich Stadial 1(HS1)事件中较轻的δ^18O和δ^13C指示大量淡水输入,水体分层加剧,向北输送的北大西洋水聚集在次表层,导致次表层水温逐渐升高。从B?lling-Aller?d(B/A)事件开始,次表层水温度达到4.5℃,表明北大西洋水流入增强。早全新世(11.7~8.2kaBP)早期次表层温度达到6.5℃,钙质生产力升高,冰筏碎屑输入降低;在中全新世(8.2~4.2kaBP)早期(8.2~5.6kaBP),钙质生产力逐渐升高反映通风作用增强,导致营养盐供应增加;6.6~5.6kaBP,明显降低的次表层温度(~4℃)反映夏季太阳辐射量降低以及大西洋水流入减弱;5.6~4.2kaBP期间次表层水变暖导致δ^18O偏轻,而δ^13C轻值反映生产力降低。晚全新世(4.2~0.8kaBP)的新冰期(4.2~3.0kaBP),次表层温度逐渐降低,Nps-δ^13C偏轻反映生产力下降,Nps-δ^18O偏轻以及IRD增加反映冰融水排放。3.0kaBP以来,生产力上升,次表层水体温度不断上升,可能是向北输送的北大西洋水增强。