Using temperature effect on seepage variations as proxy for phenological processes of basin‐scale vegetation communities     

Jiansheng Cao  Changming Liu  Wanjun Zhang  Shumin Han 《水文研究》2013,27(3):360-366

The identification of vegetation community growth season is critical for measuring the response of ecosystems to climate change. In this study, vegetation community growth season is measured via fixed‐point monitoring of dynamic short‐time processes of rock‐fissure seepage in the Taihang Mountain Region (TMR). The hydrometeorological data used in the study are obtained from tipping‐bucket flowmeters and automated weather stations in the region. Significant differences are noted in daily rock‐fissure seepage for different growth seasons. The study shows that during growth seasons, seepage processes in the TMR study area vary with air temperature. Although seepage in the region gradually decreases from 06:20 to 17:00 h, it increases from 18:00 to 06:00 h. Analysis shows a significant (R² > 0.8) negative correlation between seepage and air temperature during growth seasons. For nongrowth seasons, however, seepage processes exhibit near‐harmonic variations with air temperature. Also, although seepage during nongrowth seasons gradually increases from 02:30 to 12:30 h, it gradually decreases from 13:30 to 02:20 h. A significant (R² > 0.8) positive correlation also exists between seepage and air temperature during nongrowth seasons. During seasonal crop rotations, however, significant disorders and inconsistencies occur in the seepage processes in the study area. The observed seasonal variations in daily rock‐fissure seepages could lay the scientific basis for the adapting trends in crop growth seasons to climate change. Information on this process is critical for crop production and food security for the millions of people in China and beyond. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

应用广义S变换频谱分解技术识别松辽盆地三肇凹陷泉头组三-四段的河道砂体   总被引：3，自引：0，他引：3       下载免费PDF全文

宋永忠  张尔华  沈加刚  陈树民  高静怀  李昂 《地质科学》2009,44(2):534-544

松辽盆地三肇凹陷东部地区泉头组三-四段储层以河道砂岩为主,具有单层厚度薄、横向变化快等特点.本文将基于广义S变换的频谱分解技术应用于厚度为1～5 m的河道砂体的识别,取得了良好的效果.据此编制了研究区的河道砂体预测图,经钻井验证,证明它是对薄层河道砂体有较强识别能力的有效技术.  相似文献   

塔里木盆地古城地区鹰山组白云岩稀土元素地球化学特征及成因   总被引：1，自引：0，他引：1  

郭春涛  李如一  陈树民 《吉林大学学报(地球科学版)》2018,48(4):1121-1134

白云岩成因一直是地质学研究的热点领域。塔里木盆地塔东低隆起古城低凸起中—下奥陶统鹰山组发育厚层白云岩。为研究这些白云岩的成因,在岩心、薄片观测基础上,按照晶体粒度大小将白云岩分为泥晶白云岩、粉晶白云岩、细晶白云岩、中晶白云岩、粗晶白云岩,并对各类白云岩及缝洞充填物进行了稀土元素地球化学特征的研究。结果表明,各类白云岩及缝洞充填物稀土元素NASC配分模式分为6种类型：δCe弱正异常δEu正异常型、δCe负异常δEu强正异常型、δCe强负异常型、微右倾型、微左倾型和平坦型。分析上述6种白云岩及缝洞充填物的成因为：前2种类型形成于两期热液或不同演化阶段的同一期热液环境;第3种类型形成于蒸发泵模式;第4和第5种形成于两种性质不同的埋藏白云化流体;第6种则由渗透回流作用形成。古城地区鹰山组白云岩的成因非常复杂,成因模式多样,包括蒸发泵模式、渗透回流模式、埋藏白云化模式、热液白云化模式4种。  相似文献   

波浪水槽中振动格栅湍流特征的实验研究     

马洪余  戴德君  乔方利  蒋暑民 《海洋学报》2017,39(12):12-19

在波浪水槽中采用格栅振动的方式产生湍流,研究振动格栅产生湍流的特征。本文开展了4类实验,调节测量点到格栅平均位置的距离、格栅振动频率、振动冲程,采用ADV测量水体中单点的脉动速度。实验结果显示,湍流强度在一定范围内随离格栅距离的增大而逐渐减小,随着振动频率的增大而呈幂指数增大,随着振动冲程的增大而呈幂指数增大。同时还比较了两个不同格栅产生湍流的不同。结果显示,在波浪水槽中,振动格栅产生湍流的强度还与格栅的长度尺寸有关,这与在水箱中振动格栅产生湍流的特征不同。  相似文献   

海门一次F1级龙卷的多普勒天气雷达特征分析   总被引：4，自引：4，他引：0  

林应  陈铁  张树民  缪燕  严晓庆 《气象科学》2012,32(S1):126-133

用多普勒天气雷达、常规观测和地面加密观测资料对2011年7月13日发生在江苏南通海门市树勋镇的龙卷风过程进行了详细分析。得出:较长时间的不稳定层结的存在,较低的抬升凝结高度,较强的水平和垂直风切变以及地面干线的存在为龙卷风的发生发展提供很好的动力条件;底层冷空气的切入,较强的风切变易使单体发展更加旺盛。强回波中心高度和垂直积分液态含水量的下降,径向速度风场中气旋性涡旋的迅速发展是对龙卷风提前警戒的很好指标。龙卷风进行过程中,此系统为低位质心的对流系统,产生的天气是龙卷,伴随大风,与冰雹的高位质心对流系统有明显的区别。中气旋高度,最大切变高度的骤降,中气旋尺度的急剧收缩预示着龙卷的发生,为我们今后的龙卷风预警提供有利的参考。  相似文献   

一种基于欧拉角序列变换的影像外方位元素解算方法     

王书民  张爱武  胡少兴  孟宪刚  杨凌波 《测绘通报》2012,(2):11-13,108

IMU/DGPS组合导航定位可以获取传感器精确姿态位置数据,在低空遥感监测中具有重要应用。但是POS系统并不能直接输出影像的外方位元素,需要经过多次转换才能用于影像校正。针对不同POS系统输出航偏、俯仰、横滚角的轴序的不同,详细推导POS数据依据欧拉角序列进行余弦变换求解影像外方位元素的一般过程,并对ω-ψ-κ和Yaw-Pitch-Roll欧拉角序列作重要说明,且以NovAtel SPAN-CPT接收机为例证明该方法的正确性。  相似文献   

Kinetics of Hydrothermal Reactions of Minerals in Near-critical and Supercritical Water   总被引：9，自引：1，他引：8  

ZHANG Ronghu  HU Shumin  ZHANG XuetongOpen Research Laboratory of Geochemical Kinetics  Chinese Academyof Geological Sciences  Baiwanzhuang Ro  Beijing 《《地质学报》英文版》2000,74(2):400-405

This work presents new experimental results on the kinetics of mineral dissolution in near-critical and supercritical water in a temperature range (T) from 25 to 400℃ and a constant pressure of 23 MPa. Kinetic experiments were carried out by using a flow reactor (packed bed reactor) of an open system. The dissolution rates of albite and magnetite were measured under these experimental conditions. Na, Al and Si release rates for albite dissolution in water were measured as a function of the temperature and flow velocity in the reaction system. The maximum release rates of Na, AI and Si of albite dissolution in the hydrothermal flow systems under different flow velocities were always obtained at 300℃, that is to say, the maximum albite dissolution rates in the flow systems, regardless of different flow rates, were repeatedly measured at 300℃. Results indicate a wide fluctuation in albite dissolution rates occurring close to the critical point of water. The dissolution rates increased when the temperatu  相似文献   

金伯利岩体上中梯装置ρ_s异常的性态研究     

宁淑敏  潘玉玲  魏文博 《地质科技情报》1993,(Z1)

简要介绍了边界单元法的计算原理,以直立圆柱、圆台、蘑菇状模型模拟不同形态的金伯利岩体,用边界单元法对上述模型的中梯装置ρ_3异常进行了正演计算。着重对正演计算结果进行分析,总结出不同条件下ρ_3曲线的性态特征,所得规律有利于进一步改善中梯装置电阻率法在勘查金伯利岩中的应用效果。  相似文献   

Experimental Observation of the Ore-Forming Fluid NaCl-H_2O System in the Earth Interior   总被引：3，自引：1，他引：2  

ZHANG Ronghua  HU Shumin Open Research Laboratory of Geochemical Kinetics  Chinese Academy of Geological Sciences  Baiwanzhuang Ro  Beijing  China 《《地质学报》英文版》1999,73(1):47-64

The NaCl-H_2O binary system is a major component of solutions coexisting with ores. Observation ofsaturated solutions of NaCl-H_2O by using the method of hydrothermal diamond anvil cell (HDAC) is a new approach tothe study of ore-forming fluids. The salinities of NaCl-H_2O solutions in experimental observation are in a range of 32-55%. The observed temperature range is 25℃-850℃, and the pressure range 1 atm-10 kb. In this temperature-pressure range, the supercritical single phase, two phases (L,V) close to the critical state and two-phased (L+V) immis-cible region were observed. And for the salinity of 35% the two phase L+V immiscible region of NaCl-H_2O solutionwas observed in a range of 253-720℃. Another temperature range, 400-817℃, was observed for the immiscible two-phased region of 50% salinity solution. In the high-temperature part of the two-phased immiscible region, the phase na-ture is very unstable. A "critical phenomenon" was observed when the heating path was very close to the critical state.It is possible to observe a 'critical phenomenon': an "explosion" occurred almost constantly at the interface between theliquid and vapour and the interface is rather obscure. A continuous transition between phases L and V could be foundin the immiscible L+V phase while heating continuously. Moreover, as the NaCl-H_2O solution was separated into liq-uid and vapour phases, static charges surrounding each vapour bubble could be seen, and these bubbles were attractedtogether by the static charges to form a special solution structure. Besides, critical states of different salinities of NaCl-H_2O were observed in order to study the properties of the fluids occurring in the rocks in the earth interior, the origin ofore-bearing fluids and the significance of supercritical fluid with respect to the ore formation. The comparison of the sa-linity data of the fluid inclusions in the minerals of ore deposits with observations of NaCl-H_2O under HDAC in theconditions of high temperatures and pressures, combined with further thermodynamic analysis of ore-formation condi-tions would explain in depth the factors determining the ore formation.  相似文献   

A case study of the influx of upper mantle fluids into the crust   总被引：2，自引：0，他引：2  

Ronghua Zhang  Shumin Hu 《Journal of Volcanology and Geothermal Research》2002,118(3-4)

Geochemical and geophysical investigations in the Bohai Gulf and adjacent areas, China, indicate that uplift of the high-conductivity layer in the lithosphere coincides with the area of high heat flow. In this area are distributed abundant oil and gas fields in a Tertiary fault basin and also large quantities of basaltic rocks. Gas fields, mostly CO₂ bearing, occur at the basin margins, where a widespread alkaline olivine basalt has high contents of gold. Geochemical prospecting of the surface (soil and soil gas) in the area indicates that there is an anomaly zone of large-scale gold mineralization, and large gold deposits have been found in this area. Isotopic study demonstrates that CO₂ in the volcanic rocks and in the CO₂-bearing gas deposits are all derived from the mantle. Experiments show that Au- and CO₂-bearing hydrothermal fluids separated into vapor phase and liquid phases respectively due to a reduction of pressure and temperature over the temperature range from 250 to 290°C and at 22 M Pa. Au appears in the vapor phase rich in CO₂. That proves that it is possible that CO₂-bearing aqueous fluids (in gas phase) can carry gold and transport it from deeper parts of lithosphere to the surface.  相似文献