中国历史时期干旱区湿地及其人─地系统动力学的初步研究

本文用历史观点，初步探讨了我国干旱区湿地与人─地系统动力学机制。研究表明，虽然干旱区气候及其干暖化发展与湿地发生学相悖，但也不乏湿地分布．干旱区湿地一直处在衰退过程之中，其原因总的来说是区域性人—地系统动力学负效应综合作用的结果。     

Angular momentum of Arctic Ocean tides

Oceanic tidal angular momentum (OTAM) is calculated for the four major tides of the Arctic Ocean, based on the tidal elevations and current velocities from a recent two-dimensional numerical hydrodynamic model. The presented OTAM tables are meant to be complementary to other modeling studies that use satellite altimetry (which cannot observe Arctic Ocean tides because of ice cover and limited satellite inclinations). Although the Arctic Ocean's influence on earth rotation is, as may be expected, relatively small, the rapid advancement of the subject now calls for such small contributions to be explicitly accounted for. Received: 22 January 1996; Accepted: 5 December 1996     

中国华北地区壳内低速高导层（体）成因模式的探讨

依据高温高压下华北地区地壳主要岩石的物理性质－波速，电性测定的结果，提出了华北地区低速高导层可能的成因模式以及不同模式的适应范围。认为；碳酸盐岩在深部一定温度，压力和氧逸度条件下碳的析出会导致高导层体的出现；深部韧性剪切带组成矿物的定向排列，可使岩石的波速，电生产生各向异性行为，导致低速高导层的产生；绿片岩相和角闪岩相石中含水矿物的脱水作用会导致上，中地壳岩石物理力学性质的突变，这可能是该地区低速     

Long-term benthic population changes (1920–1930s-present) in the Barents and Kara Seas

Bottom sediment was analysed, via grab, trawl and underwater photography in 1991–1992 in the Barents, White, Kara, Norwegian and Greenland Seas, and the large scale features of macrobenthos distribution are described. The maps of alpha-diversity, biomass and trophic zone distribution on the investigated shelf are presented. Statistical assessment of the bottom community structure changes during the last 60–70 years for the Barents Sea area is presented. It is shown that on regional and transregional levels the researched communities are of natural undisturbed character and that the revealed changes may be both the result of natural processes or sampling errors. Local disturbances of benthos composition and structure, supposedly caused by man, are found to be rare not far from the Novaya Zemlya and Murman coasts.     

Metamorphic evolution of the High Himalayan Crystallines in SE Zanskar, India

ABSTRACT The High Himalayan Crystallines (HHC) of SE Zanskar consist of biotite paragneisses, of orthogneisses that derive from early-Palaeozoic granitoids, of minor metabasics and of post-metamorphic leucogranites of Miocene age. Two main metamorphic events have been documented in the HHC. The first event occurred at P= 12.0 ± 0.5 kbar and T= 750 ± 50° C in rare metabasics intruded by early-Palaeozoic granitoids. In the biotite paragneisses, thermobarometric estimates of the first event point to comparable T at P 4–5 kbar lower. The first event is followed by a pervasive syn-tectonic crystallization characterized by lower P and T. On the basis of the cooling ages of the metamorphic minerals and on the geological evidence, the second event is referred to the Tertiary Himalayan crystallization. Further petrological and geochronological studies are necessary to prove whether a few mineral relics ascribed to the first event define a polyphase Himalayan evolution or if they record the incomplete obliteration of an older history during the Himalayan event. The HHC of SE Zanskar show a decrease in metamorphic grade from the middle structural levels upward, close to the Kade unit, and downward, close to the Lesser Himalaya (from sillimanite-K-feldspar-biotite-bearing assemblages to kyanite-staurolite-muscovite-bearing assemblages). This metamorphic zonation is probably a consequence of the polyphase history of intracontinental thrusts and of the tectonic emplacement of hot crustal slabs within shallower and colder thrust sheets at relatively late stages of the continental collision between India and Eurasia.     

Geothermal observations in east Liaoning and haicheng seismic area

We have obtained altogether heat flux data of 23 drill holes including 2 observational holes of thermal flow in the Haicheng seismic area. These data show roughly thermal structure of the crust in eastern Liaoning and in the Haicheng seismic area. The results indicate that there is higher value of heat flow in the belt north by east from Liaoyang to Xiongyue, the average thermal flux being 8.29× 10⁻²J/m²·s (2.0 hfu). The average thermal fulx in the Haicheng seismic area is 9.22×10²J/m²·s (2.2 hfu). Comparing with other known geophysical data of the Haicheng seismic area, we give a geophysical section of comprehensive interpretation. We suppose the low-velocity layer in the lower crust of the Haicheng seismic area is a result from intrusion of large-scale uper mantle substance. High temperature and low velocity mean that the layer has the nature of plastic mechanics. The focal region of the Haicheng earthquake is situated right in the upper part of that plastic layer. Obviously, this result is significant for studying the seismogenic process of the Haicheng earthquake and other intra-plate earthquakes. We attempt to emphasize that observation of heat flow is necessary for earthquake study. Gu Haoding did the actual writing.     

Spectroscopic measurements of atmospheric carbon monoxide and methane. 1: latitudinal distribution

The results of spectroscopic total column measurements of CO and CH₄ at different points of the Northern and Southern Hemispheres in 1970–1985, are reported. Seasonal cycles of CO are evident for all the sites. The Northern Hemispheric long-term positive trend of CO seems to be 1.5–2% per year. In the Southern Hemisphere, temporal increasing was not detected and a possible upper limit for it is about 0.6% per year. Methane concentration in the Northern Hemisphere increases at a rate of 1.2% per year.     

Concentrations of atmospheric constituents observed at Alert,Canada, in relation to air trajectories and synoptic systems

A meteorological analysis is presented for environmental data set obtained from the Canadian Arctic haze study, which is part of AGASP-II. Results of the study indicated that atmospheric carbon dioxide (CO₂), methane (CH₄), sulphate (SO₄ ⁼), ozone (O₃) and other air pollutants observed at Alert, N.W.T. underwent periodical fluctuations. It was found that high concentrations of these atmospheric constituents were associated with a deep (1430–2074 m) inversion and with a major anticyclone. In contrast, relatively low values of these constituents were associated with a cyclonic disturbance near Alert. High concentrations of these constituents occurred with air trajectories coming from the N-W direction, while low values occurred with S trajectories. In addition, examinations of satellite imagery with other meteorological data suggested that volcanic inputs of ash and gases from Augustine Island, Alaska were negligible for the observed high values of these constituents at the ground level at Alert.     

Elemental composition of particulate material sampled from the Arctic haze aerosol

Thirty-six aerosol filter samples collected in tropospheric Arctic haze layers, in the stratosphere, and in the marine boundary layer during the 1983 Arctic Gas and Aerosol Sampling Program were analyzed for trace elements using instrumental neutron activation analysis. Average crustal dust concentrations were 540 ng/m³ and 330 ng/m³ for samples collected in Arctic haze over the North American and Norwegian Arctic, respectively. An average marine salt concentration of 120 ng/m³ was obtained for haze samples collected above the marine boundary layer on both sides of the Arctic.Meteorological and wind trajectory information were used to identify specific haze transport pathways, which brought relatively unmixed aerosol from the central Soviet Union into the AGASP sampling areas. Results from individual filters collected within these transport zones are discussed, with emphasis on certain trace metal ratos which have been proposed by other researchers as discriminators of aerosols from different source regions. Our aircraft-collected data are compared with previously-collected ground-based measurements, and show reasonably good agreement for most tracer elements and ratios. Specifically, we have determined the As/Sb ratio tracer, named by other researchers as the most effective elemental discriminator of aerosol from the central Soviet Union, to be approximately 5–6. This relatively high tracer value is consistent with previous ground-based findings. A significantly lower V/Sb ratio was observed throughout this study, possibly indicating a change in the source signature.     

Analytical electron microscope studies of size-segregated particles collected during AGASP-II,flights 201–203

Cascade impactor samples were collected over the Alaskan Arctic during the first three research flights of AGASP-II. These samples were analyzed using analytical electron microscopy to determine the morphology, mineralogy and elemental composition of individual particles. For analytical considerations, a typical impactor sample was run for approximately 20 min, thus giving excellent time resolution of discrete events.Samples collected during flights 201 and 202 consisted of stratospheric aerosol and lower-altitude haze samples. Stratospheric samples were characterized by moderate loadings of H₂SO₄ droplets with relatively few particles of other types. Samples collected in tropospheric haze layers generally exhibited light-to-moderate particle loadings. H₂SO₄ was again the most prevalent species, with crustal and anthropogenic particles also observed. One sample taken over south-central Alaska near the end of flight 203 showed high concentrations of solid crustal particles, with relatively little associated H₂SO₄. Giant particles larger than 5 m were occasionally observed in this aerosol. The composition of this material closely matches that of bulk ash from the Mt. Augustine volcano, which erupted 9–13 days before collection of this sample. This brings forth the possibility that pockets of ash-rich aerosol existed over parts of south and central Alska during the AGASP-II field mission. There is no evidence that these volcanic aerosols were present in the AGASP study area north of the Brooks Range.