Palaeomagnetism and K—Ar ages of Lower Ordovician and Upper Silurian—Lower Devonian rocks from north-west Argentina

Summary. In this paper we present palaeomagnetic data from 87 hand samples collected in a sequence of tuffs and shales (Surf Formation) of Llanvirnian age, exposed in north-western Argentina (27° 47' S, 68° 06' W). After cleaning, the majority of samples showed reversed polarity and yielded a palaeomagnetic pole at 5.9° E, 8.5° S (α₉₅= 5.9°). They also showed reversals of declination and inclination at the top of the sequence, which we have associated with geomagnetic excursions. Whole rock K—Ar age de-terminations suggest an age older than 416 ± 25 Myr for the Suri rocks. The predominant reversed stable remanence of these rocks is consistent with the reversed polarity reported for Early Llanvirnian rocks from USSR. The palaeomagnetic pole for the Suri Formation is consistent with the interpretation that Gondwana was a single unit in Early Palaeozoic times.
Palaeomagnetic data from 27 hand samples collected from 10 igneous units of Late Silurian—Early Devonian age (Ñuñorco Formation), exposed in the same area, are also given. The majority of the igneous units showed reversed polarity after cleaning. The positions of VGP's for the Ñuñorco igneous units are scattered and they are not used for geodynamic interpretations. Whole rock K—Ar age determinations suggest ages of 416 ± 25 and 360 ± 10 Myr for two igneous units of the Ñuñorco Formation.     

A study on nano－ and microdiatoms in the intertidal zones of Zhongshan Station，Antarctica

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Rock magnetic properties of recent soils from northeastern Bulgaria

In this paper, basic rock magnetic studies of Holocene loess-soil samples from northeastern Bulgaria are reported. The sites are related to the Danube river and located at different distances southwards, thus representing various pedogenic conditions. The study is primarily aimed at determining the main magnetic carrier(s) and their physical characteristics (grain-size distribution, magnetic enhancement, etc.). Oxyhydroxides, maghemite and titanomagnetites of various oxidation degrees are assumed to be the main ferromagnetic minerals present. Our results suggest that the uppermost part of recent soil profiles is rich in stable, near-single-domain (SD) particles, while the illuvial horizons are characterized by a gradual decrease in grain sizes, from highly viscous to a true superparamagnetic (SP) domain state. The properties of samples from carbonate-rich horizons of recent soils are basically controlled by detrital minerals, while those from sites with more intensive pedogenesis and especially grey forest soils are influenced by strongly magnetic minerals formed ' in situ '.     

The separation and identification of phytoplankton pigments from the adjacent waters of Great Wall Station，Antarctica

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临夏盆地三千万年来沉积物粒度特征及其构造意义*

本文通过对临夏盆地长达30m.y.的连续沉积(临夏群)共计779个样品的粒度特征分析,划分出七大完整的沉积旋回。粒度曲线明显地表示出青藏高原的强烈隆升始于距今3.4Ma前。该文还初步确定出青藏高原地区两次夷平过程最终结束的年代。     

NCEP/NCAR 再分析资料在珠穆朗玛峰 -念青唐古拉山脉气象研究中的可信性

由于珠穆朗玛峰- 念青唐古拉山脉极高山区特殊的自然环境, 这一带的气象观测资料极其匮乏。2003 年在青藏高原南部念青唐古拉山脉(30^o24'44.3"N, 90^o34'13.1"E, 5850 m a.s. l.) 建立了自动气象站; 2005 年在珠穆朗玛峰北坡垭口(28^o01'0.95"N, 86^o57'48.4"E, 6523 m a.s.l.) 建立了自动气象站。利用这两自动气象站的观测资料与NCEP/NCAR 再分析资料进行对比, 检验NCEP/NCAR 再分析数据在喜马拉雅山脉-青藏高原南部一带的可行性。研究结果表明, NCEP/NCAR 再分析资料能够较好地反映气压和气温的天气尺度的变化。但是, 再分析的气压和气温值系统性低于相应观测值, 而且, 某种程度上, 低估了实际的变化幅度; 再分析天气事件, 在珠穆朗玛峰地区, 超前于实际观测一日发生, 而在念青唐古拉地区, 基本上是与观测事件同一日发生。由于受相似大气环流的影响, 珠峰和念青两者之间的观测资料、再分析资料都高度相关。     

闽江口潮汐盐沼湿地土壤碳氮磷的空间变化

以闽江口区最大的鳝鱼滩潮汐盐沼湿地为研究对象,选择远、近潮沟区2个不同潮水水淹地段设置样线,采集3种优势植物芦苇(Phragmites australis)、咸草(Cyperus malac-censisvar.bervifolius)和藨草(Scirpus triqueter)下18个土壤剖面分层样品,分析土壤中DOC、TN和TP等含量和储量的空间分布规律及土壤物理特征对其的影响。结果表明:远、近潮沟区3种植物下土壤表层(0~10 cm)TN浓度范围为0.24~1.91g kg-1,TP为0.21~1.34 g kg-1,DOC为13.68~93.73 mg kg-1,无论是近潮沟区还是远潮沟区,芦苇和咸草下土壤DOC、TN和TP含量十分接近,且均大于藨草下土壤DOC、TN含量,藨草下土壤TN和TP含量和储量在近潮沟区均明显大于远潮沟区,而芦苇和咸草下土壤TN和TP含量在远、近潮沟区差距不大;土壤DOC、TN和TP含量与土壤粒径、容重和含水量呈显著相关,盐度对土壤中NH4+-N和NO3--N含量影响显著,与NH4+-N为正相关关系,与NO3--N为负相关关系。     

北极Barrow地区几种冻原植物的花粉形态

本文研究了北极巴罗 (Barrow)地区 1 2种冻原植物的花粉形态 ,它们的形状有球形、近球形、扁球形茧形和四合体型 ,其萌发孔有三孔沟、三沟、二合沟以及散孔等类型。花粉具辐射对称和两侧对称两种类型。这些花粉的植物体是北极冻原地区常见的植物 ,分属于 1 2个科 ,除 3种为小灌木外 ,大多数为多年生或一年生草本植物。这些冻原植物花粉形态的研究为恢复北极地区古植被和古气候的研究 ,提供了有价值的对比资料和依据。     

西藏山南地区沉错湖泊与径流水化学特征及主控因素初探

选取枪勇冰川径流-卡鲁雄曲（河）-沉错（湖）为研究区域,开展高原湖泊及其补给河流与冰川径流的水化学特征研究,并探讨影响主离子组成的主控因素。结果表明：夏季湖水主要离子呈均匀混合状态,pH值、电导率、TDS及优势阴阳离子在整个湖泊空间上变化不显著;总体上,从上游冰川融水径流、河水至下游湖泊,离子浓度呈现上升趋势;融水径流及河水的水化学类型主要受岩石风化作用控制,表现为SO₄^2--Ca²⁺-Mg²⁺类型;沉错湖水的水化学类型主要受蒸发结晶作用控制,表现为SO₄^2--Na⁺-Ca²⁺类型,在蒸发作用下Ca²⁺逐渐沉淀析出,Na⁺浓度不断升高而成为绝对优势阳离子。     

Spatial variability of phytoplankton, nutrients and new production estimates in the waters around Svalbard

Phytoplankton dynamics and carbon input into Arctic and sub-Arctic ecosystems were investigated around Svalbard, in summer 1991. Phytoplankton biomass, species composition and dissolved nutrient concentrations were analysed from water samples collected along seven transects. Phytoplankton biomass was low especially to the north (Chlorophyll-a mean 0.3 pg 1- '), where flagellates dominated the communities and only ice-diatoms were present. To the west, the phytoplankton composition was representative of a summer Atlantic community, in a post-bloom state. Zooplankton grazing, mainly by copepods, appeared to be the main control on biomass to the west and north of Svalbard.
In the Barents Sea (east of Svalbard), an ice edge bloom was observed (Chlorophyll-a max. 6.8 pgl-') and the ice edge receded at a rate of approximately 1 1 km day-'. The phytoplankton community was represented by marginal ice species, especially Phaeocystis poucherii and Chaeroceros socialis. South of the ice edge, Deep Chlorophyll Maxima (DCM) were observed, as surface waters became progressively nutrient-depleted. In these surface waters, the phytoplankton were predominantly auto- and heterotrophic flagellates.
Carbon production measurements revealed high net production (new and regenerated) to the north of the Barents Sea Polar Front (BSPF); it was especially high at the receding ice edge (reaching 1.44gC m-'day-'). To the south, a low level of production was maintained, mainly through regenerative processes.     

Modeling synthetic aperture radar (SAR) scattering from a seasonally varying snow-covered sea ice volume at 5.3 and 9.25 GHz

A series of sensitivity analyses using dielectric, mixture and microwave scattering models is presented. Data from the Seasonal Sea Ice Monitoring and Modeling Site (SIMMS) in 1990 and 1991 are used to initialize the models. The objective of the research is to investigate the role of various geophysical and electrical properties in specifying the total relative scattering cross section (ρ') of snow covered first-year sea ice during the spring period.
The seasonal transition period from the Winter SAR scattering season to Early Melt was shown to signal a transition in dielectric properties which caused the snow volume to become a factor in the microwave scattering process. The effect of the thermal insulation of a snow cover on sea ice was shown to be significant for both ε' and ε'. Higher atmospheric temperatures caused proportionally greater changes in the dielectric properties of the sea ice at the base of the snow cover. Model ρ⁰ was computed for a range of sensor, sensor-earth geometry, and geophysical properties. In the Winter season the surface roughness terms (o_hand L) were shown to have a significant impact on ρ⁰ when the ice surface was the primary scattering mechanism. Once the snow cover began to warm and water was available in a liquid phase, the ice surface became masked because of the decrease in microwave penetration depths. During this period the water volume variable dominated ρ⁰, both from its impact on ρ_v⁰, and due to its control over the dielectric mismatch created at the air/snow interface.     

基于作物空间分配模型的东北三省春玉米时空分布特征

利用1980-2010 年东北三省分县玉米播种面积与产量统计、耕地分布、农业灌溉分布以及作物适宜性分布等多源数据,结合基于交叉信息熵原理的作物空间分配模型（Spatial Production Allocation Model,SPAM）,在5'×5'的像元尺度模拟了春玉米种植面积与产量的时空分布,并重点分析了两者在纬向、经向,以及高程上的时空变化规律。结果显示：（1）玉米种植面积在2000 年前向北扩展至北纬44°~48°间,2000 年后在中南部出现大规模发展（北纬42°~44°）,并进一步向东扩展至东经123°~127°间,同时还表现为向低海拔（高程100 m以下）和较高海拔（高程200~350 m）扩展的态势;（2）单产在纬向上的增加区主要集中在北纬42°~48°,经向上的单产增加则相对均匀,高程上单产提升区主要集中在海拔350 m以下。（3）像元内玉米种植比例整体上由中低种植比例为主逐步演变为中高比例占据主体,并且中高种植比例像元对应的玉米单产水平整体上较高,反映了市场经济驱动下的玉米种植集聚化和规模化的发展趋势。     

Distribution of Chemical Constituents in Superimposed Ice from Austre Brøggerbreen, Spitsbergen

10 m and 2.3 m ice cores were obtained on Austre Brøggerbreen, Spitsbergen in Svalbard (78°53 ' N, 11°56 ' E, 450 m a.s.l.) in September 1994 and in March 1995, respectively. Stratigraphy, bulk density, pH, electrical conductivity, and major ions were obtained from the core samples.
The chemical effect of meltwater percolation through snow/ice is examined. Good correlation between Cl⁻ and Na⁺ was obtained. The ratio of Cl⁻ to Na⁺ was 1.14 which was nearly the same value as in bulk sea water. However, the variation of Cl⁻/Na⁺ shows that higher ratio occured in the bubble-free ice. Furthermore the Cl⁻ ions remain in higher concentration than SO ₄ ²⁻ or Na⁺ ions.     

新疆鸟类新纪录——白腹鹞(Circus spilonotus)

白腹鹞(Circus spilonotus)又叫东方泽鵟,在阿勒泰地区布尔津县(47°46'N, 86°49'E)有多次记录,现确定为新疆新纪录种(或亚种)。但是,在2015年5~7月繁殖期观察,发现它可能与雌性白头鹞(Circus aeruginosus)杂交。两者无论是在形态与行为,还是在地理分布隔离方面,都存在疑团,其分类地位值得商榷。     

干旱对大豆叶片葫芦巴碱含量和渗透调节的影响

以两个抗旱性不同的大豆品种绥农14号和黑农38号为研究材料,研究了土壤干旱胁迫下大豆叶片葫芦巴碱含量的变化和渗透调节能力。结果表明,土壤干旱下两个大豆品种叶片水势、渗透势和压力势降低,且绥农14号叶片的压力势在干旱胁迫下明显高于黑农38号。干旱胁迫下两个大豆品种的渗透调节能力提高。在0~8 d 干旱期间,叶片的葫芦巴碱含量增加较快,脯氨酸含量增加较慢;在8~12 d干旱期间,叶片中葫芦巴碱含量下降,而脯氨酸含量迅速增加。因此,葫芦巴碱在轻度干旱下可能起到渗透调节物质的作用,在严重干旱下该作用减弱。     

泰国的工业化及其区域政策

80年代以来,泰国经济的腾飞得益于它的工业化发展,但随之也出现了一系列的负面效应,特别是泰国首都曼谷为此面临许多十分棘手的问题。曼谷与泰国其他地区之间地区差异的不断扩大,迫使泰国政府不能不重新确立区域发展政策,但收效甚微。泰国的这些发展历程,无论成功与否,我们都可以从中得到一些经验和教训。     

西藏自治区农牧民素质对收入的影响

文章以西藏自治区为研究背景,在抽样调查的基础上综合分析西藏农牧民文化、身体和心理素质状况,结果显示西藏农牧民素质偏低是限制剩余劳动力转移、制约区域经济发展的主要因素;农牧民素质与收入水平正相关;政府针对教育和科技的投入对增加农牧民收入贡献和边际效益都较大;具有较高素质的农牧民是当地的富裕典型;西藏自治区增加农牧民收入、发展农村经济、提高农牧民生活水平、妥善解决“三农”问题的关键是提高农牧民素质。针对这一情况,文章以生态经济理论为指导提出了旨在提高农牧民素质的对策,包括加大教育投入、稳定农村科技队伍、引进科技人员、对劳动力进行短期培训等措施。     

晚白垩世以来黄山地区隆升机制研究*

文中确定了黄山三级古剥蚀面的年龄,得到了自晚白垩世以来黄山地区三次隆升的幅度。其隆升的序次与周边板块作用阶段有较好的对应关系。同时论证了黄山慈光阁U形谷实际上是发育于早第三纪当时古侵蚀基准面上的壮年期河谷。     

我国客货流时空演化及其与经济发展的空间关联分析

基于标准差椭圆和地理加权回归方法,对2000—2015年我国交通客货流时空演化特征及其与经济发展的空间关联性进行测度。结果表明:(1)受国际国内市场环境的影响,客货流标准差椭圆呈现明显的"东西往返"移动轨迹,核心区持续快速发展一段时间后出现疲软态势,转入中低速常态化发展模式,整体发展趋于均衡。(2)沿海和全国客货流标准差椭圆呈现相近的运动轨迹,呈现空间一体化发展格局。扩大内需、培育人们消费能力成为客货流发展的关键。(3)客货流与经济发展的空间关联呈现明显的空间差异,经济基础发展相对较好的城市凭借周边地区的依附作用,关联度相对较高,而发展相对有限的城市则相反。     

中国典型山地温冰川水化学空间分布特征与近期冰川动态

从我国玉龙雪玉典型温水王白水１号冰川不同区段表面融水,新近积雪和冰川初给河水采样分析结果表明,雪线以下降水中的稳定同位素的离子含量比雪线以下为高,低海拔河水比高海拨融水的氧同浓度为低,可能在来源上存在着差异,这种分布特征说明本温冰川区局部大气环流情况高度而不同,有可能存在季气候区所特有的“降水量效应”或“季节性效应”。冰川不同水体内离子浓度变化说明,冰川融水与地壳表面接触时间越久,其中的可融性离了