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在巢湖杭埠河流域中的古湖盆中心——三河圩区获取28.6 m长的湖相岩芯（SZK1507孔）,利用AMS14C测年技术建立可靠的地层年代序列,通过对SZK1507孔738 cm以上段湖相沉积物平均粒径、磁化率、总氮（TN）、总有机碳（TOC）及C/N的综合分析,高分辨率重建了巢湖杭埠河流域全新世以来的古环境演变过程.结果表明,本区域的环境变化过程可以分为4个阶段,阶段Ⅰ（约10050—9700 cal.a B.P.）与阶段Ⅲ（约9250—5300 cal.a B.P.）气候较为湿润,巢湖水位较高,平均粒径、磁化率值较低,TN、TOC、C/N也偏低;阶段Ⅱ（约9700—9250 cal.a B.P.）与阶段Ⅳ（约5300 cal.a B.P.以来）气候干燥,巢湖水量减少,水位降低,平均粒径、磁化率值、TN、TOC、C/N均较高.一些全球范围内显著发生的气候突变事件在SZK1507孔沉积记录中也有体现,如9.3、8.2和4.2 ka B.P.事件等.将巢湖杭埠河流域10000 cal.a B.P.以来的平均粒径、磁化率、TN、TOC、C/N沉积记录与全新世以来的北纬30°夏季太阳辐射量、太阳黑子数、火山喷发对大气中硫酸盐含量贡献率等进行对比,发现巢湖杭埠河流域全新世气候突变事件主要受控于北半球夏季太阳辐射量变化、太阳活动以及火山活动等因素,并与它们之间复杂的响应机制有关. 相似文献
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为查明合肥市地下空间开发地质环境影响因素,评价该市地下空间开发地质环境的适宜性,通过研究地质环境条件,选取工程地质条件、水文地质条件、地壳稳定性、地面及地下空间条件4个要素作为地下空间开发地质环境适宜性评价因子。在单因子地下空间开发适宜性评价的基础上,利用层次分析法确定权重,以MAPGIS为平台,运用模糊数学综合评价方法对合肥市地面以下40 m深度内的地下空间开发地质环境适宜性进行竖向分层评价。结果表明:合肥市地面以下40 m深度内的地下空间开发地质环境适宜性划分为适宜区、较适宜区、适宜性差区3个等级;0～-5 m空间域适宜区、较适宜区面积占70.2%;-5～-15 m空间域适宜区、较适宜区面积占81.8%;-15～-40 m空间域适宜区、较适宜区面积占92.2%。合肥市具有较好的地下空间资源,这些潜在的地下空间资源可为城市可持续发展提供保障。 相似文献
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Wu Li Sun Xiaoling Sun Wei Zhu Cheng Zhu Tongxin Lu Shuguang Zhou Hui Guo Qingchun Guan Houchun Xie Wei Ke Rui Lin Guiping 《地理学报(英文版)》2020,30(9):1451-1466
Based on archaeological surveys of Neolithic cultural development and GIS spatial analysis,this study reproduced the main characteristics of temporal distribution and settlement selection of the sites from the Neolithic Age in Anhui and identified a relationship between environmental evolution and human activity.The results show that altitude,slope direction,and slope gradient were consistent among the settlements at different stages of the Neolithic Age in Anhui,and the sites were mostly distributed in hilly and plain areas on southeast-or south-facing slopes of low gradients close to rivers.We determined that early Neolithic Age(9.0–7.0 ka BP) sites were scattered in small numbers and likely had little cultural exchange with communities of other provinces.The environmental characteristics of various regions in Anhui indicated that the climate was warm and humid with extensive water distribution.The sites of the mid Neolithic Age(7.0–5.0 ka BP) increased rapidly with wide distribution.They were mainly distributed in the plain area north of the Huaihe River and the southwestern areas of Anhui.In the mid Neolithic Age,the warm and humid climate gradually dried,and our ancestors slowly developed cultural exchanges.The largest number of sites existed during the late Neolithic Age(5.0–4.0 ka BP),and were distributed throughout the province.During this period,the overall climate was relatively dry,but humans could still obtain water and other resources through migration.The relatively benign climate facilitated cultural interaction and exchange,which increased during this time,and the Wanjiang culture matured.We also determined that as early civilization evolved,cultures in different regions responded differently to environmental changes.In humid subtropical regions,especially in low-lying plains and areas beside lakes,rivers,and coastal areas,the relatively dry climate in the late period of the middle Holocene,prefaced by a period of high humidity,was conducive to the development of human culture.The evidence from the Neolithic settlements in Anhui therefore reflects this subtropical man-land relationship between cultural development and environmental conditions. 相似文献
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Local cubic law (LCL) is one of the most commonly applied physical laws for flow in single fractures (SF) and fractured media. The foundation of LCL is Darcian flow. This experimental study examines if LCL is valid for flow in a single rough fracture and how the fracture roughness and Reynolds number (Re) affect flow. Similar to the Moody diagram for flow in pipes, a diagram for flow in a single rough fracture has been generated to relate the friction coefficient with Re and the roughness. Under the experimental condition of this study, flow appears to be substantially different from Darcian flow. The flow law of q ∝ enJm appears to be valid for describing the flow scheme where q, e, and J are the unit width flux, the average aperture, and the hydraulic gradient. The value of the power index m is found to be around 0·83 ～ 0·98, less than what has been used in Darcian flow (m = 1). The power index n is around 11·2 and 13·0, much greater than the n value used in the LCL (n = 3), and it increases with the average velocity. The Moody type of diagram shows that the friction factor for flow in SFs is influenced by Re and the roughness. It decreases with Re when Re is small, and becomes less sensitive to Re when Re is large enough. It also increases with the roughness. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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通过对毗邻中国南北地理分界线的第四系标准孔岩芯进行粒度和地球化学研究，探讨了淮北平原中更新世以来的古气候变化和沉积环境变迁。研究表明淮北平原中更新世气候在暖湿与干冷(温凉）频繁交替中总体经历了从暖湿趋于干冷，与中国东部季风区北部的温带季风气候变化趋势属同相位演变，而与受控于亚热带季风气候的长江中下游及淮河源区古气候演变模式总体呈反相位。晚更新世，气候总体经历了干冷(即温干—严寒—干冷）、温湿、转向干冷，却表现出与以长江中下游及淮河源区气候演化格局更相似，而与中国北方气候总体上由暖湿向干旱化转变步调不一致。进入全新世，淮北平原与中国南北方气候均回暖，降水相应增多。涡河流域GBK1标准孔区域沉积环境总体上经历了中更新世早中期从半深湖演化到浅湖、滨湖，到晚期湖泊快速收缩直至消失，演化为泛滥平原或河流；晚更新世以来主要为河流和泛滥平原。淮北平原区域气候变化总体上对全球变化有着积极的响应，或许因其地处中国南北地理分界线边缘，致使其气候又具区域独特性。 相似文献
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