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对内蒙、河北等地新近发现的壶穴进行详细的计量及采样分析 ,并参考国内外相关研究资料 ,认为本区壶穴是非冰成的风化风蚀穴。它的发育受到风、温度、降水、湿度、生物、地貌及岩体的结构构造等多种因子的控制。其中风化 ,尤其是盐风化等化学风化 ,是其主要控制因子 ,而风不仅加速风化 ,进行风蚀 ,并不断把风化物搬运走。作者综观国内外各类壶穴 ,并结合自己的研究成果 ,对壶穴的成因进行了类型划分 ,这些成因皆反映了特定的环境背景。本区古人类文化相当发达 ,壶穴正是在夏家店文化年代跨度内达到了相对稳定 ,气候环境、地貌过程、文化类型三者存在很好的响应互动关系。 相似文献
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We evaluated injuries to Spartina alterniflora by debris items common to North Carolina coastal waters as a function of debris type (wire blue crab pots, vehicle tires, and anthropogenic wood) and deployment duration, and monitored S. alterniflora recovery following debris removal. Injuries sustained by S. alterniflora and subsequent recovery, varied considerably between debris types. Differences were likely due to dissimilarities in the structure and composition of debris. Tires caused an immediate (within 3 weeks) and long-term impact to S. alterniflora; tire footprints remained devoid of vegetation 14 months post-removal. Conversely, crab pot impacts were not as abrupt and recovery was short-term (<10 months). We suggest that removal programs specifically target habitats that are susceptible to negative impacts (e.g., salt marsh) and prone to debris accumulation. Management would benefit from the inclusion of habitat information in removal databases. 相似文献
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Fabien Magri Ulf Bayer Christoph Jahnke V. Clausnitzer H. J. Diersch J. Fuhrman P. Möller A. Pekdeger M. Tesmer H. J. Voigt 《International Journal of Earth Sciences》2005,94(5-6):1056-1069
In several areas of the North German Basin, saline water comes close to, or even reaches the surface. Available data from
wells indicate that brine stratification is under unstable conditions in the deeper underground. In order to analyse the possible
transport mechanisms, 3D thermohaline simulations have been carried out for two different scenarios. The 3D regional model
(230×330 km) indicates that salty water is driven to the surface by hydrostatical forces from the surrounding highlands. In
addition, a smaller scale model (10×10 km) has been constructed with a grid resolution accounting for possible convective
flow. The results indicate that convective flow may play a dominant role in areas with minor topography. In summary, the complex
pattern of near surface occurrences of saline water probably results from the interaction of hydrostatic and thermal forces. 相似文献
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