珠峰地区雨季对流层大气的特征分析

利用2007年7月中国科学院珠穆朗玛峰综合观测站的边界层塔、无线电探空和风温廓线仪观测资料,分析了珠穆朗玛峰地区雨季低层大气风温湿等特征.珠峰地区雨季近地层风速、风向、温度等有明显的日变化.近地层风的日变化有两个很明显的阶段,00:00～14:30受谷风的影响而刮偏北风,14:30～24:00受冰川风的影响以偏南风为主.白天的冰川风比夜间的谷风要强些.中午13:30在600m以下存在强水平风速垂直切变,这可能是珠峰地区发生降雨的重要原因之一.低空急流在夏季比较常见.对流层平均降温率为0.685K/100m.低层大气的相对湿度一般有两个峰值高度,最大值在4000m以下,第二峰值高度不固定,到16000m以后相对湿度超不过10%.各层大气的风速风向差别较大.     

旅游活动对九华山风景区大型土壤动物群落影响

土壤动物是旅游活动对风景区生态系统影响最敏感的环境因素之一,也是旅游生态环境影响研究的重点。在九华山风景区6条主要游道附近选取了8条取样样带,样带设置与游道相垂直。每条样带按照距游道距离的不同设置4个取样样方,每个样方取枯枝落叶层并以5cm为一个层垂直向下取4层土样,用手拣法和网筛法拾取大型土壤动物。共捕获大型土壤动物2076头,隶属于3门8纲27个类群。运用多样性H′指数、集聚度等指标对不同样带和样方的不同土层中捕获的大型土壤动物类群和数量进行对比分析,结果表明:(1)九华山风景区大型土壤动物受到旅游活动的影响明显,旅游活动量越大土壤动物捕获量越少;(2)由近游道向远离游道的水平方向上大型土壤动物的类群和数量呈现递增规律;(3)在垂直分布上土壤动物向表层集聚明显,游憩活动的影响导致大型土壤动物类群和数量的表层聚集度由近游道样方向远离游道样方逐渐增大;(4)旅游活动量与各游道不同样方的捕获量呈现出不同的相关性。     

泰山大气棕色碳的光吸收特性、吸光贡献及影响因素

棕色碳是大气气溶胶中重要的吸光性物质,会影响大气光化学过程、改变区域气候。本次研究于2017年冬季和2018年春季在泰山顶采集了大气细颗粒物(PM_2.5)样品,在实验室测定了样品中棕色碳和黑碳的光吸收系数,并测定了棕色碳成分硝基苯酚类化合物的含量。测定结果表明,泰山冬、春两季PM_2.5样品中棕色碳的平均吸收系数Abs₃₆₅分别为(4.61±2.42)Mm^-1和(2.38±0.98)Mm^-1,质量吸收效率MAE₃₆₅分别为(0.72±0.12)m²/g和(0.52±0.24)m²/g,棕色碳在365 nm处的吸收系数分别占碳质气溶胶总吸收系数的(32±7)%和(20±9)%。通过对比与相关性分析,发现泰山周边地区人为活动对泰山顶上棕色碳的光学特性有重要影响,泰山冬季受邻近区域煤炭燃烧活动影响很大,排放的大量一次有机物增强了棕色碳的吸光能力和吸收系数,导致泰山冬季棕色碳的吸收系数与吸光贡献显著高于春季。根据测定结果,...     

Environmental Hazard of Capable Faults: The Case of the Pernicana Fault (Mt. Etna,Sicily

When dealing with hazard, the concept of fault capability (the probability of significant surface displacement in the near future) is more useful than the generic and often misleading concept of fault activity. The example of the Pernicana fault, located in the north-eastern flank of the Mt. Etna volcano is used here to illustrate the damage which can be expected in an urbanised area from a capable fault, in this case characterized by 'aseismic creep along part of its length. Along this fault, buildings, roads and other essential lifelines are being affected by slow, left-lateral displacement. The Pernicana fault is only one of a set of structures in the area whose movement, either connected to seismicity or not, is producing severe damage. First identified at the end of the last century, this source of hazard is, nevertheless, still poorly considered by planners and technicians. In Italy fault creep is quite rare outside the Etna region, but fault capability associated with strong earthquakes is relatively frequent, based on historical and palaeoseismological data, and is a feature that should be taken into account for hazard reduction programs.     

Chemical Composition of the Primitive Mantle Source of Peridotite Inclusions at Mount Lianshan, Liuhe County,Jiangsu Province

This paper presents a study of the major and trace element compositions of fresh mantle-derived spinel lherzolite and harzburgite inclusions from Cenozoic alkaline basalt in Mount Lianshan and Mount Panshi, Liuhe County, Jiangsu Province. An estimation is made of the contents of the major elements and some of the trace elements in the primitive mantle source region of the area, from which the authors have obtained MgO/Al2O3= 7.86. The contents of MgO and Al2O3 are also obtained as 37.58% and 4.78% respectively based on the correlation of MgO-Al2O3. Then, the contents of various elements in the primitive mantle are calculated using their regression equations with MgO, and the compositor) of the primitive mantle, a basic issue in geochemistry study, is discussed on that basis.     

Regional metamorphism and the alteration response of selected Silurian to Devonian mineral systems in the Nymagee area,Central Lachlan Orogen,New South Wales: a HyLogger™ case study

The southern Cobar Superbasin includes the Mount Hope, Cobar and Rast troughs and adjacent Winduck, Mouramba and Kopyje shelves. These stratotectonic units host a range of mineral systems within deformed upper Silurian to Lower Devonian rocks. Despite the metallogenic importance of the terrane the regional metamorphic- and alteration-related mineral assemblages have not been systematically described until now. Here, we present a study using the HyLogger? spectral scanner to systematically map changes in both background and alteration-related mineralogy for 14 mineral systems across the Nymagee area. The study found that, with the exception of the late diagenetic zone assemblages associated with the Winduck Shelf, the mineral assemblages for zones away from mineralisation are consistent with uniform sub- to lowest-greenschist facies metamorphic conditions, with no evidence for a regional, thermal field gradient across the basin. By contrast, proximal to mineralisation, there are significant changes in alteration-related mineral abundances and species reflecting elevated fluid temperatures. For several zones, including Browns Reef, Great Central, Hera, May Day, Nymagee and Shuttleton, there is a systematic change in chlorite composition from Fe- and/or Fe–Mg-chlorites to more Mg-rich varieties towards mineralisation. In addition, talc was noted for May Day, Mineral Hill and Shuttleton. The change in chlorite composition suggests that these ore-forming fluids were undersaturated with respect to iron. Furthermore, although present in discrete zones, carbonate alteration is not a dominant alteration type. However, at Manuka and Blue Mountain, the mineralisation is associated with carbonate-rich (calcite, ankerite, dolomite) units that have been dolomitised (Mg alteration) but not all dolomite-rich zones are mineralised. For Mineral Hill, there are systematic changes to mineral species/chemistry with observed data consistent with Parkers Hill being proximal to the centre of a mineralising system. The G and H Lode area (Southern Ore Zone) is slightly more distal whereas the Pearse deposit may represent a zone more distal again.     

Rhenium–osmium systematics of the Mount Isa copper orebody and the Eastern Creek Volcanics,Queensland, Australia: implications for ore genesis

The syn-tectonic breccia-hosted Mount Isa Cu deposit in northwest Queensland is the largest sediment-hosted Cu deposit in Australia. Whole-rock samples of chalcopyrite-rich Cu ore form an isochron with a Re–Os age of 1,372 ± 41 Ma. This age is more than 100 Ma younger than the previously accepted age of Cu ore formation, an Ar–Ar mineral age for biotite separated from the host rocks within the alteration envelope to the Cu orebody. This discrepancy cannot be unequivocally resolved due to a lack of other absolute geochronological constraints for Cu mineralisation or the deformation event associated with Cu emplacement. The 1,372 ± 41 Ma date may reflect (a) the time of Cu deposition, (b) the time of a hydrothermal event that reset the Re–Os signature of the Cu ore or (c) mixing of the Re–Os isotope systematics between the host rocks and Cu-bearing fluids. However, a range of published Ar–Ar and Rb–Sr dates for potassic alteration associated with Cu mineralisation also records an event between 1,350 and 1,400 Ma and these are consistent with the 1,372 Ma Re–Os age. The 1.8 Ga Eastern Creek Volcanics are a series of tholeiitic basalts with a primary magmatic Cu enrichment which occur adjacent to the Mount Isa Cu deposit. The whole-rock Os isotopic signature of the Eastern Creek Volcanics ranges from mantle-like values for the upper Pickwick Member, to more radiogenic/crustal values for the lower Cromwell Member. The Re–Os isotope signature of the Cu ores overlaps with those calculated for the two volcanic members at 1,372 Ma; hence, the Os isotope data are supportive of the concept that the Os in the Cu ores was sourced from the Eastern Creek Volcanics. By inference, it is therefore postulated that the Eastern Creek Volcanics are the source of Cu in the Mount Isa deposit, as both Os and Cu are readily transported by oxidised hydrothermal fluids, such as those that are thought to have formed the Cu orebody. The Pickwick Member yields a Re–Os isochron age of 1,833 ± 51 Ma, which is within error of previously reported age constraints. The initial ¹⁸⁷Os/¹⁸⁸Os isotopic ratio of 0.114 ± 0.067 (γOs = −0.7) is slightly subchondritic, and together with other trace element geochemical constraints, is consistent with a subcontinental lithospheric mantle source. The Pickwick Member records a minimum age of ca. 1.95 Ga for melt depletion in the subcontinental lithospheric mantle beneath the Mount Isa Inlier prior to the extraction of the magmas which formed the Eastern Creek Volcanics. This corresponds with the end of subduction-related magmatism along the eastern margin of the Northern Australian Craton, which included the Mount Isa Inlier.     

Geological evolution of Mount Etna volcano (Italy) from earliest products until the first central volcanism (between 500 and 100 ka ago) inferred from geochronological and stratigraphic data

We present an updated geological evolution of Mount Etna volcano based on new ⁴⁰Ar/³⁹Ar age determinations and stratigraphic data integrating the previous K/Ar ages. Volcanism began at about 500 ka ago through submarine eruptions on the Gela–Catania Foredeep basin. About 300 ka ago fissure-type eruptions occurred on the ancient alluvial plain of the Simeto River forming a lava plateau. From about 220 ka ago the eruptive activity was localised mainly along the Ionian coast where fissure-type eruptions built a shield volcano. Between 129 and 126 ka ago volcanism shifted westward toward the central portion of the present volcano (Val Calanna–Moscarello area). Furthermore, scattered effusive eruptions on the southern periphery of Etna edifice occurred until about 121 ka ago. The stabilization of the plumbing system on the Valle del Bove area is marked by the building of two small polygenic edifices, Tarderia and Rocche volcanoes. Their eruptive activity was rather coeval ending 106 and 102 ka ago, respectively. During the investigated time-span volcanism in Etna region was controlled by a main E–W extensional tectonic related to the reactivation of Malta Escarpment fault system in eastern Sicily. Electronic supplementary material The online version of this article () contains supplementary material, which is available to authorized users. An erratum to this article can be found at     

泰山酸雨特征及影响因素分析

利用2006—2015年泰山气象站的降水pH、电导率、降水量和风向风速资料,统计分析了泰山酸雨特征和变化趋势,探讨了降水量和风向风速对酸雨的影响。结果表明,泰山降水年均pH变化范围为4.31～4.99,酸雨发生频率达到69.3%;pH随降水量的增加而趋于5.60（中性）;5月至次年1月的月均pH与月平均过程降水量的变化趋势一致;月均电导率与月平均过程降水量的变化趋势相反。泰山降水期间盛行西南风,在南风和东北风条件下,酸雨出现频率最高且酸性最强,这主要是风速风向因素和人为排放源分布共同导致的。近10 a泰山降水酸性程度有所减弱,酸雨频率明显下降,表明近年来酸雨污染情况有所改善,有利于保护泰山生态环境。