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111.
平顶山矿区矿井突(涌)水水源判别模式   总被引:18,自引:1,他引:17  
对在平顶山矿区所采集的地下水样品进行了多元统计分析,以识别一些来源不清的样品归属,建立该区突(涌)水水源判别模型。选择水中6大离子为变量,对37个水样进行了Q型聚类分析和阳离子三角形分析;以聚类分析所得的结果为基础,应用判别分析方法建立了该矿区寒武系灰岩水、薄层灰岩水(L2)和砂岩水3类判别模型,并应用马氏距离作F检验和归属概率“检验”,结果表明所建立的判别模型是有效的。  相似文献   
112.
The profile of temperature gradient versus depth (T-log) has been found to be very useful for correlation with electrical resistivity log (E-log) in coal-bearing formations. A positive correlation between electrical resistivity and thermal resistivity is observed in coal sections whereas a negative correlation is found in sandstone/shale beds, thus helping in coal prospect evaluation. T logs have been used to correct the location of coal bed which had apparently been misinterpreted by the E-log. Hole to hole correlation of T-log and E-log is found to be excellent and it is observed that thermal resistivity characteristics of given formations remain fairly uniform. A rough estimation of coal grade is possible from the detailed study of the T-logs. Abrupt changes of temperature gradient as also its reversals have been observed in burnt coal sections.  相似文献   
113.
The headwaters of mountainous, discontinuous permafrost regions in north‐eastern Mongolia are important water resources for the semi‐arid country, but little is known about hydrological processes there. Run‐off generation on south‐facing slopes, which are devoid of permafrost, has so far been neglected and is totally unknown for areas that have been affected by recent forest fires. To fill this knowledge gap, the present study applied artificial tracers on a steppe‐vegetated south‐facing and on two north‐facing slopes, burned and unburned. Combined sprinkling and dye tracer experiments were used to visualize processes of infiltration and water fluxes in the unsaturated zone. On the unburned north‐facing slope, rapid and widespread infiltration through a wet organic layer was observed down to the permafrost. On the burned profile, rapid infiltration occurred through a combusted organic and underlying mineral layer. Stained water seeped out at the bottom of both profiles suggesting a general tendency to subsurface stormflow (SSF). Ongoing SSF could directly be studied 24 h after a high‐intensity rainfall event on a 55‐m hillslope section in the burned forest. Measurements of water temperature proved the role of the permafrost layer as a base horizon for SSF. Repeated tracer injections allowed direct insights into SSF dynamics: A first injection suggested rather slow dispersive subsurface flow paths; whereas 18 h later, a second injection traced a more preferential flow system with 20 times quicker flow velocities. We speculate that these pronounced SSF dynamics are limited to burned slopes where a thermally insulating organic layer is absent. On three south‐facing soil profiles, the applied tracer remained in the uppermost 5 cm of a silt‐rich mineral soil horizon. No signs of preferential infiltration could be found, which suggested reduced biological activity under a harsh, dry and cold climate. Instead, direct observations, distributed tracers and charcoal samples provided evidence for the occurrence of overland flow. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
114.
Early Pleistocene vegetation in upland southeastern Australia included diverse rainforests and sclerophyll forests, which alternated on precessional timescales. The nature and timing of transitions between these biomes, and the role of fire in maintaining or driving transitions between them, are uncertain. Here we present a high‐resolution pollen record from Stony Creek Basin, a small Early Pleistocene palaeolake in southeastern Australia. The pollen record documents a pattern of vegetation change, over ca. 10 ka at ca. 1590–1600 ka, between sclerophyll forests, dominated by Eucalyptus, Callitris (Cupressaceae) or Casuarinaceae, and rainforests dominated by either angiosperms or conifers of the family Podocarpaceae. Transitions between these biomes typically occurred within ca. 1–2 ka. The associated charcoal record suggests that greatest biomass combustion occurred when local vegetation was dominated by Eucalyptus, and the least biomass combustion occurred when local vegetation was dominated by Podocarpaceae. However, local fires burnt in both sclerophyll and angiosperm‐dominated rainforest vegetation, at least once every several centuries. Fire was very rare (less than about one fire per millennium) only when the local vegetation was rainforest dominated by Podocarpaceae. This suggests that fire was an irregular presence in both sclerophyll‐ and angiosperm‐dominated rainforest biomes during the late Neogene, though was largely absent in Podocarpaceae‐dominated rainforests. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   
115.
Accelerated runoff and erosion commonly occur following forest fires due to combustion of protective forest floor material, which results in bare soil being exposed to overland flow and raindrop impact, as well as water repellent soil conditions. After the 2000 Valley Complex Fires in the Bitterroot National Forest of west‐central Montana, four sets of six hillslope plots were established to measure first‐year post‐wildfire erosion rates on steep slopes (greater than 50%) that had burned with high severity. Silt fences were installed at the base of each plot to trap eroded sediment from a contributing area of 100 m2. Rain gauges were installed to correlate rain event characteristics to the event sediment yield. After each sediment‐producing rain event, the collected sediment was removed from the silt fence and weighed on site, and a sub‐sample taken to determine dry weight, particle size distribution, organic matter content, and nutrient content of the eroded material. Rainfall intensity was the only significant factor in determining post‐fire erosion rates from individual storm events. Short duration, high intensity thunderstorms with a maximum 10‐min rainfall intensity of 75 mm h?1 caused the highest erosion rates (greater than 20 t ha?1). Long duration, low intensity rains produced little erosion (less than 0·01 t ha?1). Total C and N in the collected sediment varied directly with the organic matter; because the collected sediment was mostly mineral soil, the C and N content was small. Minimal amounts of Mg, Ca, and K were detected in the eroded sediments. The mean annual erosion rate predicted by Disturbed WEPP (Water Erosion Prediction Project) was 15% less than the mean annual erosion rate measured, which is within the accuracy range of the model. Published in 2007 by John Wiley & Sons, Ltd.  相似文献   
116.
117.
玉山煤矿含煤地层为吴家坪组,可采煤层2层,具有中灰、中等挥发分、高硫分、低磷分、特低—低氯,低砷、高氟,中高发热量的煤质特征,煤类丰富,呈条带状分布。通过对区内沉积环境和煤的变质作用2个方面的分析,阐述了形成煤层高硫、中灰特征的影响因素,解释了煤类分带现象,并指出了主要煤质指标的变化规律。  相似文献   
118.
应用地面磁法圈定煤田火区边界   总被引:4,自引:1,他引:3  
陈敏  邵伟 《物探与化探》2010,34(1):89-92
针对煤层自燃区自燃边界确定问题,通过对比分析陕北某地实测地面高精度磁场特征与钻孔勘探结果,认为采用ΔT垂向一阶导数方法能够 有效地圈定煤层自燃边界。  相似文献   
119.
煤矿开采对地下水的影响及其脆弱性评价   总被引:2,自引:0,他引:2  
张伟 《地下水》2010,32(1):13-14
在我国由于煤矿的大量开采,地下水资源的数量和质量受到严重影响,并且破坏了水的动态平衡和生态环境。一方面分析了采矿对地下水的破坏,另一方面通过对地下水的脆弱性评价警示人们在开发利用煤炭资源的同时对地下水资源采取有效的防治保护措施。  相似文献   
120.
Here, we present two high-resolution records of macroscopic charcoal from high-elevation lake sites in the Sierra Nevada, California, and evaluate the synchroneity of fire response for east- and west-side subalpine forests during the past 9200 yr. Charcoal influx was low between 11,200 and 8000 cal yr BP when vegetation consisted of sparse Pinus-dominated forest and montane chaparral shrubs. High charcoal influx after ∼ 8000 cal yr BP marks the arrival of Tsuga mertensiana and Abies magnifica, and a higher-than-present treeline that persisted into the mid-Holocene. Coeval decreases in fire episode frequency coincide with neoglacial advances and lower treeline in the Sierra Nevada after 3800 cal yr BP. Independent fire response occurs between 9200 and 5000 cal yr BP, and significant synchrony at 100- to 1000-yr timescales emerges between 5000 cal yr BP and the present, especially during the last 2500 yr. Indistinguishable fire-return interval distributions and synchronous fires show that climatic control of fire became increasingly important during the late Holocene. Fires after 1200 cal yr BP are often synchronous and corroborate with inferred droughts. Holocene fire activity in the high Sierra Nevada is driven by changes in climate linked to insolation and appears to be sensitive to the dynamics of the El Niño-Southern Oscillation.  相似文献   
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