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《中国科学:地球科学》2015,(1)
为了探讨不同的变形机制对无烟煤化学结构的影响,从而深入研究构造煤的化学结构的改变与瓦斯突出之间的相互关系,本文采用沁水盆地南部晋城矿区的无烟煤进行了10组次高温高压实验,并且对实验前后样品进行了傅里叶变换红外光谱(FTIR)、激光拉曼光谱(Raman)和镜质组反射率(VR)的测试和分析.结果表明,除温度对煤化学结构影响较为明显外,应变速率对煤的化学结构也有明显影响.在较高应变速率(4×10~(-5) s~(-1))下,煤主要表现为脆性变形,样品发育具有明显位移的主破裂面,煤化学结构总体变化规律不明显;随着应变速率的降低,韧性变形作用渐趋增强,应变能不断积累,导致煤大分子结构发生晶内位错、滑移,缩合芳环数量和次生结构缺陷数量亦随之增加,脂族和醚键氧等官能团相继裂解析出,形成分子量更低的小分子,产生CO气体.此外,变形实验后样品的Ro,max值均明显大于变形前样品,暗示构造变形作用促进了煤的变质作用,同时镜质组反射率椭球(VRI)是反映构造变形作用类型的有效指标. 相似文献
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岩石圈黏度是大陆动力学研究中一个重要参数,但是岩石圈黏度,尤其是横向小尺度(<100 km)黏度结构的确定是一个挑战.本文根据电阻率和黏度与它们控制因素的相似关系,直接把一条跨过青藏高原东缘和四川龙门山断裂带的大地电磁(MT)探测的电阻率剖面转换成黏度结构作为输入,在GPS速度和地表地形数据的约束下,利用地球动力学数值模拟获得了该剖面的二维地壳/岩石圈黏度结构.本文推断的黏度与前人获得的区域尺度的黏度值一致,但揭示出了更多的细节.本文的黏度结构揭示出研究区域内的地壳/岩石圈黏度存在较大的空间变化范围(约5量级),黏度值分布在1.48×10^17~8.44×10^22 Pa·s之间;龙门山断裂带下的黏度存在强烈的小尺度横向变化,其中、下地壳的黏度分别为1.99×10^18~8.21×10^20 Pa·s(平均1.17×10^20 Pa·s)和4.09×10^19~7.08×10^20 Pa·s(平均1.77×10^20 Pa·s).基于该黏度结构的地球动力学模型表明驱动青藏高原中-下地壳物质流动的可能是热-化学浮力,以及上地壳和中-下地壳可能处于解耦状态.本文获得的黏度结构可以为龙门山断裂带地震成因和机制、岩石圈小尺度变形和构造应力状态的深入研究提供重要的帮助. 相似文献
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贵州草海湿地不同水位梯度土壤碳、氮、磷含量及其生态化学计量比分布特征 总被引：1，自引：0，他引：1
对贵州草海湿地4种水位梯度下(农田区、过渡区、浅水区和深水区)表层土壤(0~10 cm)碳、氮、磷含量及其生态化学计量比进行研究,以期揭示草海湿地不同水位梯度下土壤碳、氮、磷生态化学计量比的分布特征及其影响因素.结果表明:土壤总有机碳(TOC)、总氮(TN)及总磷(TP)含量在不同水位梯度之间均差异显著,由过渡区至深水区,土壤TOC及TN含量均呈递增趋势,而TP含量呈先降低后增加的趋势;农田区土壤TN含量显著高于浅水区,但深水区土壤TP含量显著低于农田区.不同水位梯度土壤碳氮比(C/N)、碳磷比(C/P)和氮磷比(N/P)也存在显著差异,由过渡区至深水区,土壤C/P和N/P均呈递增趋势,而C/N呈先增加后降低的趋势;与过渡区相比,农田区土壤C/N、C/P和N/P总体偏低.相关性分析表明:土壤C/N、C/P和N/P的空间分布与土壤TOC、TN、含水量等理化性质有关.可见,草海湿地水位变化对土壤TOC、TN和TP含量以及C/N、C/P及N/P的空间分布具有显著影响,且水位升高有利于增强土壤碳、氮、磷的固存潜力. 相似文献
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不同湿地植物对污水中氦磷去除的贡献 总被引：5，自引：0，他引：5
选择5种湿地植物(芦苇、东方香蒲、菖蒲、茭白、鸢尾)和1种喜湿灌木(蒿柳),研究重度富营养化水体中植物的生长特性和氮磷去除效果.研究发现,所选用的6种植物在实验池中均生长良好.稳定生长105d以后,各种植物的总生物量在424-1772g/m2之间,除了香蒲的地上地下生物量比(A/U)达到3.23外.其它的比值在0.63-1.49之间.6种植物地上部N和P浓度分别在13.12-28.83mg/g及1.55-3.77mg/g之间,地下部N和P浓度在7.76-15.60mg/g及1.70-2.71mg/s之间,大部分植物地上部N和P的浓度大于地下部.6种植物平均氮、磷积累量分别为20.60g/m2和3.08g/m2,其中地上部平均氮、磷积累量分别占66.60%和58.22%.不同植物筛选池对不同污染物的净化效果有差异,鸢尾池对TN的净化效果最好,芦苇池对TP的净化效果最好.植物的氮、磷积累量与浓度及生物量之间均存在显著相关. 相似文献
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2007年8月至2008年9月,对厦门两个淡水水体(芙蓉湖、厦大水库)的叶绿素浓度和遥感反射率(Rrs)进行了连续观测.在叶绿素浓度6-322mg/m3的范围,Rrs光谱出现显著的近红外反射峰,中心位置在700-710nm之间,较之通常的荧光峰中心(683nm)向长波方向偏离.该峰在厦大水库始终出现在700nm,但在芙蓉湖存在时间变化,随着叶绿素浓度的增加,由705红移到710nm.由此,仿MODIS荧光高度(FLH)的定义,定义该峰的高度(简写为REH),对于水库和美蓉湖中心波段分别确定为700和710nm.REH与叶绿素浓度呈现显著相关,美蓉湖REH=0.0161g(chl)-7.8×10-6(R2=0.79,n=41),水库REH=0.0001chl+0.0002(R2=0.74,n=32).可见对十高散射的淡水藻华水体,可以并且需要通过改进FLH的波段选择,基于更长波段处的近红外峰的高度探测叶绿素浓度. 相似文献
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本文使用国内首次搭载飞行的静电悬浮加速度计在轨数据与卫星姿态数据,对加速度计与卫星质心的相对位置进行了估计测量.文中分析得到,在卫星姿态机动时,加速度计的输入加速度主要来自于离心加速度及角加速度引入的线加速度.结合卫星姿态机动时陀螺仪的测量数据,使用最小二乘法对加速度计质心位置的三个分量进行了联合估计.结果表明:质心位置的估计精度达到约6 mm水平,主要受限于卫星平台条件和加速度计测量精度限制.利用本文方法对未来重力卫星任务进行了分析,若使用精度为1×10~(-10)m·s~(-2)加速度计以及2角秒分辨率的星敏感器,可将质心位置估计精度提高至4.6×10~(-6)m水平. 相似文献
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藏南沉错钻孔沉积物金属元素分布特征及其与粒度的关系 总被引：4，自引：1，他引：3
从沉积物磷的化学形态特征、沉积物-水界面的环境条件和水库的水文参数等角度探讨了山仔水库沉积物磷对上覆水体的磷浓度贡献,并从沉积物间隙水与水体垂向溶解性磷的浓度梯度估算对水体磷浓度的贡献大小．结果表明：山仔水库沉积物具有大的释放磷的潜力,沉积物间隙水和水体之间存在着明显的溶解性磷的浓度梯度,沉积物的溶解性磷释放通量在0．0420—0．167μg／（cm^2·d））之间,沉积物磷对水体营养贡献大小在0．7％-6％之间,其中秋冬季节沉积物磷对水体的贡献大于春夏季节,当外源减少时,沉积物磷负荷在一定时间内将成为水库营养状态的重要贡献因子。 相似文献
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橄榄石-尖晶石相转变流变学的实验研究 总被引：2，自引：0，他引：2
对(Mgx,Ni1-x)2GeO4系统中橄榄石-尖晶石两相混合物的流变性进行了实验研究.利用不同温压条件对混合物进行热压,得到的橄榄石和尖晶石的比例不同.温度为1 573K,试件的化学组成从x=0.95-0.70时,得到的两相材料从100%橄榄石到100%尖晶石.三轴压缩试件为圆柱状,直径8mm,两相混合物的平均颗粒尺寸为2.21-9.43μm.流变学试验在气体介质试验机中进行,围压为300MPa,温度为1 073-1 573K.试验分为常应力和常位移率两种,差应力σ1-σ3为45-320MPa,应变率在2.8×10-6-2.8×10-5s-1之间,将实验测得的混合物力学性质与两端材料的强度进行对比,发现两相多晶介质的强度介于两端材料的强度之间.当橄榄石到尖晶石的相变发生在变形过程中时,尖晶石比率的增加使得多晶材料的总体强度上升. 相似文献
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《国际泥沙研究》2014,(4)
正Director:Shangfu Kuang,China Vice-directors:Chunhong Hu,China Duihu Ning,China Guangquan Liu,China The International Research and Training Center on Erosion and Sedimentation(IRTCES)was jointly set up by the Government of China and UNESCO on July 21,1984.It aims at the promotion of international exchange of knowledge and cooperation in the studies of erosion and 相似文献
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《中国科学:地球科学(英文版)》2014,(3)
正SCIENCE CHINA Earth Sciences,an academic journal cosponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China,and published by Science China Press and Springer,is committed to publishing high-quality,original results in both basic and applied research. 相似文献
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Richard D. Hey 《地球表面变化过程与地形》1979,4(1):59-72
Feedback mechanisms, which operate upstream through drawdown and backwater effects and downstream through sediment discharge are responsible for channel evolution. By combining these mechanisms with channel processes it euables a dynamic process-response model to be developed to simulate the initial evolution of straight gravel-bed channels. When erosion commences on a land surface, sediment entrained in the headwater reach by hydraulic action is selectively transported, deposited and reworked. This produces a damped oscillation between degradation and aggradation as the channel and valley respond to spatial and temporal variations in sediment calibre and hydraulic conditions. The initial cut and fill phases are responsible for valley incision and floodplain development while secondary and subsequent activity can produce river terraces. Eventually sediment entrainment in the headwaters declines as slopes are reduced. Subsequent channel evolution is relatively insignificant because it is dependent on local weathering activity producing material that can be transported on declining slopes. Therefore landforms produced during the initial phase of development, when local weathering was non-limiting, dominate the landscape. 相似文献
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Based on relocating the Jiujiang-Ruichang earthquake sequence which occurred on November 26, 2005 in Jiangxi Province with the double-difference （DD） algorithm and master event technique, the paper discusses the focal mechanism of the main shock （MsS.7） and the probable seismo-tectonics. The precise relocation results indicate that the average horizontal error is 0.31kin in a EW direction and 0.40kin in a NS direction, and the average depth error is 0.48kin. The focal depths vary from 8kin to 14kin, with the predominant distribution at 10kin - 12kin. The epicenter of the main shock is relocated to be 29.69^oN, 115.74^oE and the focal depth is about 10.Skin. Combining the predominant distribution of the earthquake sequence, the focal mechanism of the main shock and the tectonic conditions of N-E- and NW-strike faults growth in the seismic region, we infer that the main shock of the earthquake sequence was caused by a NW striking buried fault in the Rnichang basin. The nature of seismic faults needs to be further explored. 相似文献
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《水文科学杂志》2013,58(6)
Abstract The western reservoirs represent the principal groundwater system in Morocco. Demographic, industrial and agricultural developments during the last decade have markedly altered groundwater quality. The Mamora coastal aquifer system is among the Atlantic systems which are most heavily threatened by pollution. Agricultural and industrial activities, and rapid urban growth contribute to the pollution of the groundwater. Contamination transport is facilitated by a high permeability of the aquifer formations. In order to assess the actual groundwater quality of the Mamora aquifer and to understand the influence of the factors generating the pollution, an extensive multidisciplinary research programme is in progress, with hydrochemistry and microbiology playing essential roles. The present paper concerns the spatial distribution of physico-chemical parameters in the groundwater, subjected to domestic, industrial and agricultural pollution. Fifty-seven samples were analysed for several parameters (Ca2+, Mg2+, Na+, K+, Cl?, SO4 2?, HCO3 ?, NO3 ?, pH, electrical conductivity and temperature). The microbiological analysis of 143 samples reveals the presence of four kinds of indicator bacteria in the groundwater resources: faecal Streptococci, faecal coliform, Escherichia coli and Clostridium. The physico-chemical results and bacteriological monitoring show that the nitrate and bacteria concentrations exceed the maximum admissible levels, notably around pumping stations in the sectors of Sidi Taibi, Sidi Ahmed Taleb and Aïn Sbaâ. Contamination is generated by uncontrolled anthropogenic activities and accentuated by the high intrinsic vulnerability of the aquifer system. Several parameters appeared to exceed admissibility standards. Measures are recommended to prevent groundwater pollution in the region. 相似文献
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K.-G. Malle 《洁净——土壤、空气、水》1992,20(4):196-204
Zinc in the Environment. In 1990 the world production of zinc ammounted to 7 Mio. metric tons. The main areas of application were: galvanization, alloys like brass and zinc metal. The content in the earth crust varies between 10–300 ppm zinc with a mean of 70 ppm. Uncontaminated surface waters contain less than 10 mg/m3 zinc. Apart from civilization air contains 1–10 ng zinc per m3. These background concentrations are exceeded by orders of magnitude in zinc deposit areas and where anthropogenic influences predominate. Accumulation can occur in sediments and sewage sludge. Molluscs and Algae also accumulate zinc. Zinc is essential for live. With normal food the zinc supply of man is just sufficient. Bioaccumulation of zinc towards man or chronic oversupply of man is not known. Zinc has no teratogenic or mutagenic effects, a suspicion on a carcinogenic effect proved wrong. In stockbreeding and plant cultivation a minimum supply of zinc is necessary. Plants are relatively less sensitive against higher soil contents of zinc. Considering the toxicological and ecotoxicological effects of zinc in the environment, the critical organismens are marine invertebratae like tubifex, daphnia, gammarus and algae. But normally only a minor part of the total zinc contest is biologically available, depending on salt content and pH of the waters. 相似文献