天山东部冰川积雪中大气粉尘的沉积特征

对我国天山东部三个研究点乌鲁木齐河源1号冰川、奎屯哈希勒根51号冰川和哈密庙尔沟平顶冰川积雪中大气粉尘沉积进行了分析研究。微粒特征分析表明,自西向东随着研究点地理环境的变化,积雪中不溶微粒的质量浓度、沉积通量和体积粒径分布众数都表现出增高趋势：奎屯哈希勒根51号冰川最小,乌鲁木齐河源1号冰川次之,哈密庙尔沟平顶冰川最大;三个研究点粒径0．57〈d〈26μm微粒的平均质量浓度分别是969μg／kg、1442μg／kg、3690μg／kg,年均沉积通量分别是58．2μg／cm^2、72．1μg／cm^2、73．8μg／cm^2。表明,哈密冰川受粉尘源影响较大．而乌鲁木齐河源与奎屯河源区受影响则相对较小。雪坑微粒浓度剖面和离子相关性分析表明,天山东部冰川积雪中污化层富含亚洲粉尘的富Ca^2＋、Na^2＋矿物;微粒体积一粒径分布众数介于3-22μm．粒径分布显示了单结构模式。研究区最近4年积雪的污化层剖面揭示了春季零星的粉尘浓度峰值以及沉积数量上较大的年际变化,意味着天山东部雪冰中粉尘沉积对大气环境变化的敏感性。     

天山奎屯河哈希勒根51号冰川雪坑化学特征及环境意义

2004~2007年在天山奎屯河哈希勒根51号冰川采集3个雪坑样品。运用相关分析、海盐示踪法等方法,对化学要素的季节变化特征及主要阴阳离子来源进行分析研究。结果表明,雪坑中不溶粉尘和主要化学离子具有明显的季节变化特征;春季期间降雪中粉尘浓度明显高于其他季节。主要离子的浓度在沙尘季节也明显高于非沙尘季节。雪坑中Ca²⁺是主要阳离子,SO₄^2-是主要阴离子。除NO₃^-外,雪坑中其他离子浓度之间均存在较好正相关。表明冰川区主要受中亚地区沙尘活动影响;同时雪坑中的离子(尤其是Na⁺)除陆源矿物粉尘之外,一定程度源于海洋源。     

青海苏干湖表层沉积物粒度分布模式 与大气粉尘记录

位于干旱区柴达木盆地具有年纹层的苏干湖是以地下水补给为主的内陆封闭湖泊, 其表层沉积物粒度具有多组分峰态分布特征, Weibull 函数的拟合结果发现, 其粒度分布全部具 有4 个基本组分: 超细粒组分, 众数粒径在1 μm 上下; 细粒组分, 众数粒径在5~10 μm; 粗粒组分, 众数粒径在50~100 μm; 砂组分, 众数粒径在500 $m 左右。粒度主峰出现在细 粒组分或者粗粒组分。直接来自大气粉尘的冬季湖泊冰面样品及当地尘暴样品的Weibull 函数粒度拟合也显现出了相似的分布模式, 冰面样品的粒度主峰位于众数粒径在15~20 μmm 的 细粒组分, 砂组分(众数粒径452.9μm) 的出现指示出砂粒在冬半年沿冰面而进入湖泊中心。 尘暴降尘样品在尘暴季节(5 月份) 和非尘暴季节(11 月份) 的粒度分布普遍具有3 个组分, 缺少砂组分, 强沙尘暴事件样品则由4 个组分组成, 粒度主峰均位于众数粒径在100~200 μm 的粗粒组分。结果显示, 苏干湖湖泊沉积能够较好记录当地大气粉尘, 砂组分与湖泊周边干旱地表经历的近地面强沙尘活动有关, 粗粒组分记录了区域性的尘暴事件, 细粒组分主要反映 流域径流状况, 超细粒组分代表干旱区的大气背景粉尘和气溶胶。研究表明, 苏干湖内陆湖 泊沉积客观记录了区域大气粉尘和尘暴事件, 具有重建干旱区大气粉尘变化历史的潜在优势。     

祁连山浅山区降水化学的环境意义

通过连续收集降水样品对祁连山浅山区民乐县大气降水特征及水汽来源进行研究,运用相关分析和主成分因子分析,探讨了2013 年5 月27 日至2014 年7 月7 日祁连山民乐地区降水常量离子的化学特征。结果表明：研究时段内降水离子浓度由大到小依次为Ca²⁺ >SO₄^2- >NH₄⁺ >Cl^- >Na⁺ >NO₃^- >Mg²⁺ >K⁺,其中Ca²⁺和SO₄^2-是高浓度离子,阳离子总浓度远远高于阴离子总浓度。降水pH 平均值为7.44,降水电导率的变化范围为4.0 μs·cm^-1～940.0 μs·cm^-1,平均值为167.93 μs·cm^-1。Ca²⁺离子和SO₄^2-离子分别占阳离子和阴离子总浓度的47%和44%。各阴阳离子随季节变化表现出明显的波动趋势,冬、春季节降水极少时阴阳离子浓度较高,而在夏季降水较多时各离子浓度较低。冬春季频繁的沙尘暴活动造成大气陆源气溶胶浓度升高,且该时段降水量少,因此降水离子浓度升高。相关分析和主成分因子分析结果表明,祁连山浅山区民乐县的降水化学离子主要来源于陆源物质,农业生产和人类活动产生的气溶胶是次要来源。     

天山乌鲁木齐河源1号冰川大气气溶胶和新雪中可溶性离子关系研究

在2007年4月、8月和10月三个时段内,分昼夜采集了23个气溶胶样品和7个新降雪样品,对样品中的可溶性离子进行了分析。结果表明,乌鲁木齐河源1号冰川(以下简称1号冰川)春、夏、秋三个季节气溶胶平均载量为86.22 neq/m³,分析显示1号冰川存在NH₄HSO₄和(NH₄)₂SO₄气溶胶,并有少量NH₄NO₃气溶胶存在。气溶胶和新雪样品中可溶性离子成分变化趋势相似,气溶胶浓度升高,新雪样品的浓度也会有所升高,反之亦然。气溶胶和新雪中Ca²⁺、Mg²⁺、Na⁺、Cl^-、K⁺的相关性很好,说明雪中这些离子的浓度基本能反映大气中的状况;对气相和颗粒相并存的NH₄⁺和NO₃^-来说,雪中的离子浓度和大气中的离子浓度不相关。     

蒙古高原风蚀颗粒物空间过程数值模拟及预报

基于WRF-IWEMS耦合模型对2016年3月1~9日发生在蒙古高原的强沙尘天气过程进行数值模拟,着重模拟了尘源、粉尘传播路径以及粉尘扩散过程中浓度变化和影响范围,并采用卫星影像、站点监测数据与模型结果进行对比分析。结果表明：此次风沙天气过程的尘源分布在新疆哈密地区、阿拉善高原、中蒙边境戈壁地区以及浑善达克沙地部分地区,粉尘自源区分别沿河西走廊、贺兰山区、张家口等地扩散至华北和京津地区。蒙古高原土壤风蚀可使华北地区来自自然源的大气颗粒物PM₁₀、PM_2.5浓度分别达到1 000 μg·m^-3、200 μg·m^-3以上,还可使华北地区大气颗粒物浓度高于200 μg·m^-3的天气持续48 h以上。     

基于泥炭记录的过去150 a东北山地大气粉尘沉降

为了探究过去150 a来大气粉尘沉降历史及其对季风边缘区和季风影响区的影响差异,利用长白山典型雨养泥炭灰分粒度、成岩化学元素、²¹⁰Pb和¹³⁷Cs年代等指标重建过去大气粉尘变化,并与大兴安岭摩天岭雨养泥炭粉尘记录进行比较。东北山地泥炭灰分主要以粘土颗粒和粉砂颗粒物为主。中值粒径和成岩元素特征也初步揭示东北山地泥炭中矿物灰分主要源于蒙古国和中国北方沙漠和沙地的土壤尘。大气土壤尘降通量自19世纪初至20世纪60年代表现出逐渐增加的趋势,与区域近代化、工业化和战争等人类活动强度增加一致。在过去60 a间具有减小的趋势,与区域自然尘暴的监测数据吻合较好。东北地区长距离传输的大气土壤尘降通量背景基线为(5.2±2.6) g m^-2 a^-1。长白山大气土壤尘降通量（5~38 g m^-2 a^-1）小于大兴安岭（14~68 g m^-2 a^-1）,揭示了大气尘降随着与尘源区的距离增加而递减,对东北地区西部的影响要强于对东部的影响。     

天山南坡科其喀尔冰川作用区CO2通量观测研究

冰川融水径流的发育和形成过程中,存在大量水化学侵蚀,尤其是K/Na长石及碳酸盐的水解作用,可能消耗水体中H⁺,促使大气CO₂溶于水形成重碳酸盐,影响区域碳循环。2015年7月21日-2017年7月18日选取相对平坦开阔的西天山科其喀尔冰川表碛物覆盖区,利用涡度相关法进行CO₂通量监测。结果表明：大气CO₂通量介于-17.99~3.59 g·m^-2·d^-1之间,平均值为-2.58 g·m^-2·d^-1,说明研究区是一个显著的碳汇。净冰川区系统CO₂交换量主要受大气CO₂通量支配,但日内变化显著,白天因冰雪消融导致大气CO₂沉降于融水中促进区域水化学侵蚀,而夜间因太阳辐射减少,冰雪消融减弱甚至停止,抑制了区域CO₂沉降,甚至再生冰的形成引起溶解于液态水中的CO₂释放。净冰川区系统CO₂交换量与气温呈显著的负相关关系,即气温升高,大气CO₂沉降量增加;当降水量小于8.8 mm时,交换量随降水量变化不显著,而降水量大于8.8 mm时,CO₂沉降量随降水量增加而减少。净冰川区系统CO₂交换量随日径流量的变率遵循：积雪消融期 > 积雪积累期 > 冰川消融前期 > 冰川消融后期 > 冰川消融峰期,意味着积雪消融存在时,系统CO₂交换量随日径流量变率较大,可能是因积雪本身的阻尼作用或积雪期水文通道不发育,积雪融水较冰川冰融水汇集相对较慢,为可溶性物质化学反应提供充分时间,增强了CO₂沉降。     

天山哈密榆树沟冰川冰尘特征及其成因

利用2011年8月在哈密榆树沟冰川采集的5个冰样,通过石蜡切片技术、16SrRNA系统发育分析及无机颗粒粒度分析方法,结合野外考察,对榆树沟冰川冰尘(cryoconite)的结构特征及形成过程进行了分析研究。结果表明:榆树沟冰川冰尘粒径为0.22～2.9mm,由有机部分(蓝藻、有机质)与无机部分(无机矿物颗粒)结合形成球状聚合体,它的生长具有季节性并且具有生长、裂解交替循环的生命周期;通过核糖体DNA扩增片段限制性内切酶分析(Amplifed Ribosomal DNA Restriction Analysis,ARDRA),将蓝藻16SrRNA基因文库中的214个阳性克隆分为9个不同的操作分类单元(Operational Taxonomic Unites,OTUs)。经过基因测序、BLAST比对及系统发育分析将9个OTUs归为:颤藻目,色球藻目和未定类群,其中颤藻目为冰尘中蓝藻的绝对优势类群;冰尘中无机矿物颗粒(d3.5μm)在数量上占绝对优势,体积分布的粒径众数值为14μm,较其它冰川而言,粒径众数较大。经估算,冰尘中有机部分所占比例明显大于无机颗粒,故影响冰川消融区表面反照率的主要因素为冰尘中的有机部分。     

近50年来祁连山冰川变化——基于中国第一、二次冰川编目数据

基于修订后的祁连山区第一次冰川编目(1956-1983年)和最新发布的第二次冰川编目数据(2005-2010年),对祁连山区冰川变化进行分析。结果表明:1祁连山区现有冰川2684条,面积1597.81±70.30 km2,冰储量约84.48 km3。其中,甘肃省和青海省各有冰川1492条和1192条,面积分别为760.96 km2和836.85 km2。2祁连山区冰川数量和面积分别以面积1.0 km2的冰川和面积介于1~5 km2的冰川为主;冰川平均中值面积海拔为4972.7 m,并自东向西由4483.8 m逐渐上升为5234.1 m。3疏勒河流域冰川面积和冰储量最大,占祁连山冰川总量的31.91%和35.11%;其次是哈尔腾河流域,巴音郭勒河流域冰川面积最小,为2.20 km2;黑河流域是祁连山区冰川平均面积最小的四级流域,冰川平均面积仅0.21 km2。4近50年间祁连山冰川面积和冰储量分别减少420.81 km2(-20.88%)和21.63 km3(-20.26%)。面积1.0 km2的冰川急剧萎缩是该区冰川面积减少的主要原因,海拔4000 m以下山区冰川已完全消失,海拔4350~5100 m区间冰川面积减少量占冰川面积总损失的84.24%。冰川数量和面积在各个朝向均呈减少态势,其中朝北冰川面积减少最多,朝东冰川面积减少最快,而西北朝向冰川变化最为缓慢。5祁连山冰川变化呈现明显的经度地带性分异,东段冰川退缩较快,中西段冰川面积减少较慢。     

2001-2017年祁连山积雪面积时空变化特征

科学监测祁连山积雪面积及变化特征对该区域气候研究、雪水资源开发利用、环境灾害预报及生态环境保护等具有重要意义。基于2001—2017年MOD10A2积雪产品和气象数据，分析祁连山积雪面积动态变化特征及与气温降水关系。结果显示：（1）2001—2017年祁连山积雪面积年际波动趋势较大，呈减小趋势，多年平均积雪面积约为5x104 km2，占祁连山总面积的25.9%；年内变化成 “M”型，即在一个积雪年中有两个波峰和波谷，波峰出现在11月和1月，波谷出现在7月；季节变化波动趋势较大，夏冬季积雪面积减小趋势大于春季，秋季呈现略微增加趋势。（2）祁连山区积雪面积主要分布在3 000~4 000 m及4 000~5 000 m，积雪覆盖率随着海拔上升呈现逐渐增大的趋势；祁连山区不同坡向积雪覆盖面积差异较大，积雪覆盖率差异较小；积雪频率高值区呈典型的条带状分布，与祁连山地形相一致，呈西北-东南分布，积雪频率高值区的分布西部大于东部。（3）初步分析认为祁连山积雪面积变化对气温要素更敏感。     

Source and environmental significance of oxalate in Laohugou Glacier No. 12, Qilian Mountains,Western China

Retrieval of oxalate from snow and ice provides information on past environmental changes. In recent years, records of organic acids in middle-and low-latitude glaciers have attracted the attention of researchers globally. In this study, we analyzed oxalates in an ice core from Laohugou Glacier No. 12 on the Qilian Mountains at an elevation of 5,040 m a.s.l. in2006. Average oxalate concentration was 18.5±2.4 ng/g over the prior 46 years. Oxalate values showed a significantly increasing trend since 1985. From 1985 to 1995, oxalate concentrations had large fluctuations, peaking in about 1987 and exhibiting a slightly decreasing trend since 1995. The result shows that the abrupt increase of oxalate concentration in the ice core since the mid-1980 s reflects atmospheric environmental pollution by human and industrial activities.     

The pH value and electrical conductivity of atmospheric environment from ice cores in the Tianshan Mountains

Electrical Conductivity Measurement(ECM) from ice core is a representative index for atmospheric environmental change.The pH value and ECM from three shallow ice cores(each 3.85 m,231 ice samples total) on Glacier No.1 at the headwater of Urumqi River,Glacier No.48 in Kuitun area,and Miaoergou Glacier in Hami area in the eastern Tianshan Mountains,western China,were measured and analyzed for atmospheric environment records research.Ice core record shows that the changing trend of pH and ECM in three sites in recent years is different:ECM in Kuitun increases with the ice depth change,but ECM in Hami and Urumqi Glacier No.1 ice cores show a decreasing trend.Average ECM value in Hami is much larger than other two sites,just as the dust concentration and ions concentration are also very high in this site.ECM records in all three sites are mainly affected by aerosol mineral dust of Central Asia,and correlative coefficients of ECM and mineral ions such as Ca2+,Mg2+,Na+ are all significantly high.The pH value and ECM are also significantly high correlative coefficients in the eastern Tianshan Mountains.Comparison between the eastern Tianshan Mountains and other sites in western China,and Polar Regions,shows that the difference of ECM can very well reflect the spatial difference of worldwide atmospheric environment.     

天山东部冰芯pH值和电导率的大气环境空间差异

Electrical Conductivity Measurement (ECM) from ice core is a representative index for atmospheric environmental change. The pH value and ECM from three shallow ice cores (each 3.85 m, 231 ice samples total) on Glacier No.1 at the headwater of Urumqi River, Gla-cier No.48 in Kuitun area, and Miaoergou Glacier in Hami area in the eastern Tianshan Mountains, western China, were measured and analyzed for atmospheric environment re-cords research. Ice core record shows that the changing trend of pH and ECM in three sites in recent years is different: ECM in Kuitun increases with the ice depth change, but ECM in Hami and Urumqi Glacier No.1 ice cores show a decreasing trend. Average ECM value in Hami is much larger than other two sites, just as the dust concentration and ions concentra-tion are also very high in this site. ECM records in all three sites are mainly affected by aerosol mineral dust of Central Asia, and correlative coefficients of ECM and mineral ions such as Ca2+, Mg2+, Na+ are all significantly high. The pH value and ECM are also significantly high correlative coefficients in the eastern Tianshan Mountains. Comparison between the eastern Tianshan Mountains and other sites in western China, and Polar Regions, shows that the difference of ECM can very well reflect the spatial difference of worldwide atmospheric environment.     

SNOW-AVALANCHE HAZARDS IN GLACIER NATIONAL PARK,MONTANA: METEOROLOGIC AND CLIMATOLOGIC ASPECTS

Hazardous snow avalanches in Glacier National Park, Montana, are associated with a variety of meteorologic conditions: heavy snow; heavy snows followed by a rise in air temperature to above freezing; a rise in air temperature to above freezing, without precipitation; and rain in association with above-freezing air temperatures. Years of major, widespread avalanching may be recognized by examination of historical information and tree-ring data. Avalanche types include slab avalanches, wet snow avalanches, and dry loose snow avalanches. February is the peak avalanche month. Intraannual seasonalities of avalanche trigger mechanisms and type of avalanche are related. The presence of sun crusts in some cases provides unstable stratigraphic planes in the snowpack over which freshly deposited snow may glide. Destructive windblasts also occur in association with some avalanches. Insufficient data from east of the Continental Divide precluded a comparison of avalanche type and trigger mechanisms from the western and eastern portions of Glacier National Park. The general avalanche climate is more similar to that reported from the southern Canadian cordillera than to continental locations such as the mountains of Colorado. [Key words: Snow avalanches; avalanche trigger mechanisms; avalanche types; avalanche seasonality; Glacier National Park, Montana; northern Rocky Mountains; hazard planning.]     

Glacier changes in the Qilian Mountains in the past half-century: Based on the revised First and Second Chinese Glacier Inventory

Glaciers are the most important fresh-water resources in arid and semi-arid regions of western China. According to the Second Chinese Glacier Inventory (SCGI), primarily compiled from Landsat TM/ETM+ images, the Qilian Mountains had 2684 glaciers covering an area of 1597.81±70.30 km2 and an ice volume of ~84.48 km³ from 2005 to 2010. While most glaciers are small (85.66% are <1.0 km²), some larger ones (12.74% in the range 1.0–5.0 km²) cover 42.44% of the total glacier area. The Laohugou Glacier No.12 (20.42 km²) located on the north slope of the Daxue Range is the only glacier >20 km² in the Qilian Mountains. Median glacier elevation was 4972.7 m and gradually increased from east to west. Glaciers in the Qilian Mountains are distributed in Gansu and Qinghai provinces, which have 1492 glaciers (760.96 km²) and 1192 glaciers (836.85 km²), respectively. The Shule River basin contains the most glaciers in both area and volume. However, the Heihe River, the second largest inland river in China, has the minimum average glacier area. A comparison of glaciers from the SCGI and revised glacier inventory based on topographic maps and aerial photos taken from 1956 to 1983 indicate that all glaciers have receded, which is consistent with other mountain and plateau areas in western China. In the past half-century, the area and volume of glaciers decreased by 420.81 km² (–20.88%) and 21.63 km³ (–20.26%), respectively. Glaciers with areas <1.0 km² decreased the most in number and area recession. Due to glacier shrinkage, glaciers below 4000 m completely disappeared. Glacier changes in the Qilian Mountains presented a clear longitudinal zonality, i.e., the glaciers rapidly shrank in the east but slowly in the central-west. The primary cause of glacier recession was warming temperatures, which was slightly mitigated with increased precipitation.