黔西南Au-As-Hg-Tl矿化区毒害金属元素的水地球化学

研究了黔西南典型Ａｕ－Ａｓ－Ｈｇ－Ｔｌ矿化区内毒害金属元素在采矿活动和自然状态影响下的水地球化学特征及其环境效应。结果表明,已开采的Ｈｇ－Ｔｌ矿区地下水和地表水中均有很高的毒害金属元素,煤采区地下水中亦表现出类似的特征,而Ｈｇ－Ｔｌ矿区外围地下水中金属元素保持在较低的水平。Ｈｇ－Ｔｌ矿区地素水中Ａｓ和Ｔｌ的分布模式表明,其含量的变化受矿区地下水排泄和尾矿淋滤作用的控制。在尚未开采的金矿区,浅层地下     

A new approach for reconstructing glacier variability based on lake sediments recording input from more than one glacier

We explore the possibility of building a continuous glacier reconstruction by analyzing the integrated sedimentary response of a large (440 km²) glacierized catchment in western Norway, as recorded in the downstream lake Nerfloen (N61°56’, E6°52’). A multi-proxy numerical analysis demonstrates that it is possible to distinguish a glacier component in the ~ 8000-yr-long record, based on distinct changes in grain size, geochemistry, and magnetic composition. Principal Component Analysis (PCA) reveals a strong common signal in the 15 investigated sedimentary parameters, with the first principal component explaining 77% of the total variability. This signal is interpreted to reflect glacier activity in the upstream catchment, an interpretation that is independently tested through a mineral magnetic provenance analysis of catchment samples. Minimum glacier input is indicated between 6700–5700 cal yr BP, probably reflecting a situation when most glaciers in the catchment had melted away, whereas the highest glacier activity is observed around 600 and 200 cal yr BP. During the local Neoglacial interval (~ 4200 cal yr BP until present), five individual periods of significantly reduced glacier extent are identified at ~ 3400, 3000–2700, 2100–2000, 1700–1500, and ~ 900 cal yr BP.     

人为强迫和自然强迫对近年来对流层顶高度变化的贡献

观测表明,自1979年以来对流层顶（平流层与对流层之间的界限）高度增加了数百米。在气候模式实验中,等量的增加也是显而易见的。气候模式实验表明,人为因素导致臭氧和均匀混合温室气体的变化,对1979-1999年对流层顶高度增加的影响占所有因素的80％。臭氧对平流层的冷却作用和均匀混合的温室气体对对流层的加热作用,使对流层顶高度增加。     

East Asian winter monsoon: results from eight AMIP models

 This study evaluates simulations of the East Asian winter monsoon in eight GCMs that participated in the Atmospheric Model Intercomparison Project (AMIP). In addition to validating the mean state of the winter monsoon, the cold surge and its transient properties, which includes the frequency, intensity, preferred propagation tracks, and the evolution patterns of the surges, are examined. GCM simulated temporal distribution of the Siberian high and cold surges is also discussed. Finally, the forcing of the cold surges on the tropical surface wind and convection, along with their interannual variation is analyzed. The mean state of the winter monsoon is generally portrayed well in most of the models. These include the climatological position of the Siberian high, the 200 hPa divergent center, and the large-scale wind patterns at the surface and the 200 hPa. Models display a wide range of skill in simulating the cold surge and its transient properties. In some of the models, the simulated cold surge trajectory, intensity, frequency, propagation patterns and source regions are in general agreement with those from the observed. While in others, the models cannot adequately capture these observed characteristics. The temporal distribution of the Siberian high and cold surges were realistically reproduced in most GCMs. Most models were able to simulate the effect of the cold surges on the tropical surface wind, although a few models unrealistically generated subtropical southerly wind in the mid-winter. The relationship between cold surges and the tropical convection was not satisfactorily simulated in most models. The common discrepancies in the winter monsoon simulation can be attributed to many factors. In some models, the reason is directly related to the improper location of the large-scale convective center near the western Pacific. The satisfactory simulations of the monsoon circulation and the cold surges are partly due to the topographical characteristics of the East Asian continent, i.e., the Tibetan Plateau to the west and the oceans to the east. The correct simulation of the interannual variation of the surface wind near the South China Sea (SCS) and the maritime continent is a demanding task for most of the models. This will require adequate simulations of many aspects, including tropical convection, the Siberian cold dome, the extratropical-tropical linkage, and the air-sea interaction. The discrepancies noted here furnish a guide for the continuing improvement of the winter monsoon simulations. Improved simulations will lead to an adequate delineation of the surface wind and convection near the maritime continent, which is essential for portraying the winter monsoon forcing in a coupled model. Received: 10 March 1997/Accepted: 4 June 1997     

Characteristics of over-water surface stress during strex

Surface stress values obtained from the NOAA Ship OCEANOGRAPHER during STREX indicate that wind speed and stability dependent bulk derived stress values are two to three times too low in surface pre-frontal, pre-trough and pre-ridge regions of transiting synoptic systems. The measured stress values were based on calculations of turbulent kinetic energy dissipation rates using hot film measured velocity variances. Bulk stress values obtained with wind speed (neutral drag coefficient) and stability dependencies in the Large and Pond derivation agreed very well with the measured values in other regions of the synoptic systems. In situ wave information was not adequate to relate differences to coupled vector wind and wave fields. However, analyses and interpretation of wind and stability effects suggest that wind wave interaction was the reason for the observed sub-synoptic (mesoscale) stress enhancements.     

Temporally varying ethylene emission on Jupiter

Ethylene (C₂H₄) emission has been measured in the poles and equator of Jupiter. The 949 cm⁻¹ spectra were recorded with a high resolution spectrometer at the McMath-Pierce telescope at Kitt Peak in October-November 1998 and at the Infrared Telescope Facility at Mauna Kea in June 2000. C₂H₄ is an important product of methane chemistry in the outer planets. Knowledge of its abundance can help discriminate among the various proposed sets of CH₄ photolysis branching ratios at Ly-α, and determine the relative importance of the reaction pathways that produce C₂H₂ and C₂H₆. In the equatorial region the C₂H₄ emission is weak, and we were only able to detect it at high air-mass, near the limb. We derive a peak equatorial molar abundance of C₂H₄ of 4.5×¹⁰⁻⁷-1.7×¹⁰⁻⁶ near 2.2×¹⁰⁻³ mbar, with a total column of 5.7×¹⁰¹⁴-2.2×¹⁰¹⁵ molecules cm⁻² above 10 mbar depending upon choice of thermal profile. We observed enhanced C₂H₄ emission from the poles in the regions where auroras are seen in X-ray, UV, and near infrared images. In 2000 we measured a short-term change in the distribution of polar C₂H₄ emission; the emission in the north IR auroral “hot spot” decreased by a factor of three over a two-day interval. This transient behavior and the sensitivity of C₂H₄ emission to temperature changes near its contribution peak at 5-10 microbar suggests that the polar enhancement is primarily a thermal effect coupled with vertical transport. Comparing our observations from Kitt Peak and Mauna Kea shows that the C₂H₄ emission of the northern non-“hot spot” auroral regions did not change over the three-year period while that in the southern polar regions decreased.