极光粒子沉降研究:谱形式及其在极区大气中的传输

分析了近年来南极地区极光沉降粒子的卫星、火箭、地面观测和研究结果,分别给出了极光椭圆区、极盖区、南大西洋异常区和极尖／极隙区粒子沉降的形式来源和特点。并根据磁尾研究的新进展,提出极光粒子沉降谱存在另外两种形式谱：（１）κ分布谱;（２）κ分布加上一个或多个脉冲谱,这两种谱来源于磁尾中性片区（绝热区非绝热区）。南极不同的区域,极光粒子有不同的沉降特点。这些沉降对极区电离层产生极大的影响。根据带电粒子在磁化大气中运动的Ｆｏｋｋｅｒ Ｐｌａｎｋ 方程,利用带电粒子在大气中传输的电离理论,导出极光粒子谱在极区大气中传播的解析表达式,对各种极光粒子谱在极区中的演化规律加以分析,并以此来解释在南极地区探测到的不同高度的极光电子谱的演化     

不同栽杉代数土壤抗蚀性的变化

采用标准地定位研究方法对杂木林及１代,２代,３代和４代杉木人工林土壤颗粒,土壤团聚体组成进行比较分析,结果表明：杂木要受人为干扰少,土壤颗粒及土壤团聚体组成较好,抗蚀性最好;但１代,２代,３代和４代分别是在杂木林及前１代林的采伐迹地上经再度干扰建立起来的,土壤结构破坏率加大,土壤团聚体稳定性减小,因而随着杉木林取代杂木林及杉木连栽代数增加,土壤抗蚀性减弱。     

海水中碳酸根与固体粒子的相互作用

本文研究了海水中碳酸根在固体粒子上的吸附。碳酸根在各种因素颗粒物上的吸附程度上大小顺序为：赤铁矿〉δ－ＭｎＯ２〉水锰矿〉ＳｉＯ２,最大吸附量可达到约２ｍｇＣ／ｇ吸附剂,且最大吸附值均在天然海水ｐＨ（ｐＨ８）左右。在低ＰＨ时,碳酸根对ＮａＣｌ介质中砷酸根的吸附没有影响,在高ｐＨ时,则降低了砷酸根在固体颗粒物上的吸附量,因此碳酸根的存在对其他阴离子的吸附会产生竞争作用。     

A new approach to the Nd residence time in the ocean: the role of atmospheric inputs

Concentrations of rare earth elements (REE) and Nd isotopic ratios were analyzed for seawater, filtered suspension and sediment trap samples collected in the tropical Atlantic Ocean (EUMELI program, EUtrophic, MEsotrophic and oLIgotrophic sites, 20°N, 18°–21°W). This is the first REE/Nd dataset on solution and different-sized particles collected at the same site. We present direct evidence of the Nd isotopic exchange between particulate lithogenic fraction and seawater without significant mass transfer. This exchange is probably one of the main factors that simultaneously constrains the Nd concentration and isotopic ratio budget. We propose a new approach to estimate the residence time of Nd in the ocean (τ_Nd) based on isotopic exchange: 200 yr < τ_Nd< 1000 yr. The exchange requires a partial dissolution of lithogenic Nd. We estimate that the fraction of soluble Nd proportion in atmospheric dust is of the order of 20% based on the isotopic ratios. We suggest that the partial dissolution of atmospheric fallout is probably one of the main REE sources of the ocean.     

Observation of Filterable Bromine Variabilities During Arctic Tropospheric Ozone Depletion Events in High (1hour) Time Resolution

The halogen ions Br^- and Cl^- together with NO₃ ^-, SO₄ ⁼, MSA^- (methane sulfonate), Na⁺ and NH₄ ⁺ were analysed by ion chromatography in extracts of more than 800 aerosol cellulose filter samples taken at Ny Ålesund, Svalbard (79°N, 12°E) in spring 1996 (March 27 - May 16) within the European Union project ARCTOC (Arctic Tropospheric Ozone Chemistry). Anticorrelated variations between f-Br (filterable bromine, i.e. water soluble bromine species that can be collected by aerosol filters) and ozone within the arctic troposphere were evaluated at a resolution of 1 or 2 hours for periods with depleted ozone and 4 hours at normal ozone. A mean f-Br concentration of 11 ng m^-3 (0.14 nmol m^-3) was observed for the whole campaign, while maximum concentrations of 80 ng m^-3 (1 nmol m^-3) were detected during two total O₃-depletion events (O₃ drop to mixing ratios below the detection limit of < 2 ppb). Anticorrelation between f-Br and O₃ was also seen during minor O₃-depletion episodes (sudden drop in O₃ by at least 10 ppb, but O₃ still exceeding the detection limit) and even for ozone variations near its background level (40-50 ppb). A time lag of about 10 hours between the change of ozone and of f-Br concentrations could only be found during a total ozone depletion event, when f-Br reached its maximum values several hours after ozone was totally destroyed. Bromine oxide (BrO) concentrations, measured by DOAS (Differential Optical Absorption Spectroscopy), and f-Br showed a coincident variability during almost the entire campaign (except in the case of total O₃-loss). Frequently enhanced anthropogenic nitrate and sulphate concentrations were observed during O₃-depletion periods. At O₃ concentrations < 10 ppb sulphate and nitrate exceed their typical mean level by 54% and 77%, respectively. This may indicate a possible connection between acidity and halogen release.     

Testing electric field models using ring current ion energy spectra from the Equator-S ion composition (ESIC) instrument

During the main and early recovery phase of a geomagnetic storm on February 18, 1998, the Equator-S ion composition instrument (ESIC) observed spectral features which typically represent the differences in loss along the drift path in the energy range (5–15 keV/e) where the drift changes from being E × B dominated to being gradient and curvature drift dominated. We compare the expected energy spectra modeled using a Volland-Stern electric field and a Weimer electric field, assuming charge exchange along the drift path, with the observed energy spectra for H⁺ and O⁺. We find that using the Weimer electric field gives much better agreement with the spectral features, and with the observed losses. Neither model, however, accurately predicts the energies of the observed minima.     

相对湿度对大气气溶胶粒子短波辐射特性的影响

利用Mie散射原理和重庆实测气溶胶资料,详细计算了边界层内单个气溶胶粒子的光学特性参量,气溶胶粒子群体的散射、吸收、消光系数及不对称因子、散射比、光学厚度;进而采用二流近似和累加法计算了边界层内太阳短波辐射增温率。目的在于研究相对湿度对以上各特性参量的影响。结果表明,相对湿度在65%～95%之间变化时,对气溶胶粒子群体光学特性参数和太阳增温率的影响在量级上可与气溶胶粒子浓度成倍变化的影响相比拟。     

Microanalysis of Fe3+/ΣFe in oxide and silicate minerals by investigation of electron energy-loss near-edge structures (ELNES) at the Fe M 2,3 edge

The Fe M _2,3-edge spectra of solid solutions of garnets (almandine-skiagite Fe₃(Al_1–xFe_x)₂[SiO₄]₃ and andradite-skiagite (Fe_1–xCa_x)₃Fe₂[SiO₄]₃), pyroxenes (acmite-hedenbergite (Ca_1–xNa_x)(Fe²⁺ _1−xFe³⁺ _x)Si₂O₆), and spinels (magnetite-hercynite Fe(Al_1–xFe_x)₂O₄) have been measured using the technique of parallel electron energy-loss spectroscopy (EELS) conducted in a transmission electron microscope (TEM). The Fe M _2,3 electron energy-loss near-edge structures (ELNES) of the minerals exhibit a characteristic peak located at 4.2 eV and 2.2 eV for trivalent and divalent iron, respectively, prior to the main maximum at about 57 eV. The intensity and energy of the pre-edge feature varies depending on Fe³⁺/ΣFe. We demonstrate a new quantitative method to extract the ferrous/ferric ratio in minerals. A systematic relationship between Fe³⁺/ΣFe and the integral intensity ratio of the main maximum and the pre-edge peak of the Fe M _2,3 edge is observed. Since the partial cross sections of the Fe M _2,3 edges are some orders of magnitude higher than those of the Fe L _2,3 edges, the Fe M _2,3 edges are interesting for valence-specific imaging of Fe. The possibility of iron valence-specific imaging is illustrated by Fe M _2,3-ELNES investigations with high lateral resolution from a sample of ilmenite containing hematite exsolution lamellae that shows different edge shapes consistent with variations in the Fe³⁺/ΣFe ratio over distances on the order of 100 nm. Received: 14 April 1998 / Revised, accepted: 8 March 1999     

浙江新昌地幔岩捕虏体中的硫化物包裹体初步研究

浙江新昌一带晚第三纪碱性玄武岩中地幔岩（二辉橄榄岩）捕虏体内存在大量硫化物熔体包裹体。电子探针分析表明,硫化物相成分主要为镍黄铁矿,次为磁共铁矿。硫化物包裹体的Ｎｉ／Ｆｅ值与寄主地幔岩的橄榄石含量呈正相关。同一包裹体的硫化物相成分不均一,自中心至边缘硫化物的Ｎｉ／Ｆｅ、（Ｆｅ＋Ｎｉ）／Ｓ值和Ｎｉ呈均呈增加趋势。通过与中国汉诺坝、德国ＷｅｓｔＥｉｆｅｌ东欧Ｎｏｇｒａｄ－Ｇｏｍｏｒ地区资料的综合分析,     

POLAR spacecraft observations of helium ion angular anisotropy in the Earth’s radiation belts

New observations of energetic helium ion fluxes in the Earth’s radiation belts have been obtained with the CAMMICE/HIT instrument on the ISTP/GGS POLAR spacecraft during the extended geomagnetically low activity period April through October 1996. POLAR executes a high inclination trajectory that crosses over both polar cap regions and passes over the geomagnetic equator in the heart of the radiation belts. The latter attribute makes possible direct observations of nearly the full equatorial helium ion pitch angle distributions in the heart of the Earth’s radiation belt region. Additionally, the spacecraft often re-encounters the same geomagnetic flux tube at a substantially off-equatorial location within a few tens of minutes prior to or after the equatorial crossing. This makes both the equatorial pitch angle distribution and an expanded view of the local off-equatorial pitch angle distribution observable. The orbit of POLAR also permitted observations to be made in conjugate magnetic local time sectors over the course of the same day, and this afforded direct comparison of observations on diametrically opposite locations in the Earth’s radiation belt region at closely spaced times. Results from four helium ion data channels covering ion kinetic energies from 520 to 8200 KeV show that the distributions display trapped particle characteristics with angular flux peaks for equatorially mirroring particles as one might reasonably expect. However, the helium ion pitch angle distributions generally flattened out for equatorial pitch angles below about 45°. Significant and systematic helium ion anisotropy difference at conjugate magnetic local time were also observed, and we report quiet time azimuthal variations of the anisotropy index.