湖陆风效应为主导的地面弱风预报方法

对博斯腾湖东南陆地风场数据进行计算,结合湖陆风效应初步建立夏半年各月风场日变化模型,得出风场日变化的4个典型时段。结果表明,区域测站一致性系数和风场有较好的对应关系,一致性系数小于50说明风向不稳定且风速较小,一致性系数大于80说明风向趋于稳定且风速一般较大,弱风时段主要出现在日出日落前后,且具有2h左右的持续时间。该方法为该地区弱风时段预报提供了思路,在稳定的高压脊形势下效果尤为明显。     

Stable isotope geochemistry of dissolved chloride in relation to hydrogeology of the strongly exploited Quaternary aquifers,North China Plain

Deep Quaternary groundwater is the main source for industrial, domestic, and agricultural water supply in the North China Plain (NCP). There is currently a regional decline of groundwater levels, deterioration of water quality and environmental geological problems induced by increasing exploitation of the NCP Quaternary aquifer system. To trace sources and transport processes of dissolved Cl⁻ in a regional aquifer system and to reveal hydrogeological characteristics of Quaternary complexes, δ³⁷Cl, δ¹⁸O and δD, and chemical compositions (including F⁻, Cl⁻, Br⁻) of the deep groundwater sampled from the northern flow system of the NCP were measured along the west–east groundwater flow paths. The measured δ³⁷Cl values decreased from 0.39‰ to −2.22‰ (SMOC) along the groundwater flow direction, with increasing Cl⁻ concentrations. Marine aerosol input via rainfall is the main source of Cl⁻ in the deep groundwater near the recharge areas, and subsequent evaporation/evapotranspiration appears to be responsible for Cl⁻ accumulation. Mixing of recharge water with water of high-Cl⁻ and low-δ³⁷Cl accounts for the pattern of δ³⁷Cl and Cl⁻ concentration observed in Aquifer-3 along the west–east transect. The water with high-Cl and low-δ³⁷Cl is likely from pore water released from compacted clays induced by over-exploitation of deep groundwater, suggesting that clay is a dominant subsurface source of Cl⁻ for groundwater where a regional depression cone is present in the Quaternary aquifers. The groundwater of Aquifer-4 in the Huang-Hua depression is potentially mixed with an upward flux of Cl⁻ from the Neogene aquifer through subvertical faults. Diffusion and ion filtration are two mechanisms invoked to explain the highly negative δ³⁷Cl data for groundwater of Aquifer-4 in the Yanshan–Haixing areas, which provides new insight into solute migration and the hydraulic relationship in the strongly exploited groundwater system. This study using the conservative solute Cl⁻ provides additional important information for further investigations of the geochemistry of a wide range of reactive solutes in the Quaternary aquifer system, so guiding water resource management.     

Earthquake activity in mainland China, 2003： The heaviest damage caused since 1977

The earthquake activity and damage in mainland China in 2003 are reviewed. There were 27 earthquakes with a magnitude of over 5.0, resulting in 319 people killed and 7147 people injured. The total economic loss of over 560 million US dollars represents the highest figure for mainland China since 1977, and it is comparable to the total loss during one decade in the 1980‘s. For the first time China International Search and Rescue(CISAR) teams were dispatched to disaster areas in China, Algeria and lran.