农业土地利用对岩溶地下水影响研究综述   总被引：4，自引：4，他引：0  

贾亚男 《中国岩溶》2003,22(4):306-312

地球表层系统最突出的景观标志是土地利用/土地覆被。人类通过土地利用改变天然土地覆被从而对脆弱敏感的岩溶水文系统产生了重大的影响。文章着重从农业土地利用出发综述了当前农业土地利用对岩溶水影响的研究。农业土地利用对岩溶地下水的影响主要围绕着水质和水量两个核心从以下几个方面展开:天然植被的清除,农业灌溉和排水,农业集约化所带来的化肥杀虫剂等的使用以及污染物质在岩溶含水层中的运移和影响。在此基础上作者从研究内容,理论方法和建立模型等方面都提出了自己的想法和建议。   相似文献   

OBSERVATION OF THE GAS RADON AND RADON IN GROUNDWATER AT PANJIN Ⅰ WELL     

WANG Ya-nan  LIU Jian-guang  ZHANG Wei-dong  DONG Yan-tao  XIAN Shu-dong 《东北地震研究》2008,24(3)

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刚性桩复合地基水平承载力特性     

屠毓敏  俞亚南 《岩土力学》2007,28(11):2329-2332

利用三维非线性弹性有限元方法,研究了刚性桩复合地基在不同垂直荷载作用下的水平承载力特性,分析了不同褥垫层厚度及其地基土的性质对复合地基水平受力特性的影响,得出了水平荷载作用下桩身弯矩和挠度的分布规律。研究表 明,垂直荷载的大小改变了复合地基水平荷载作用下的破坏模式,直接影响着其水平承载力;适当的垫层厚度可降低桩所分担的水平荷载,有利于桩身的安全。  相似文献   

冀南綦村斑状石英二长岩角闪石环带结构及其地质意义     

范琳琳  卢静  张聚全  金雅楠  白富生  唐玉莹  秦超 《矿物岩石地球化学通报》2021,40(4):903-913

为阐释岩浆两阶段演化过程及其与铁成矿的关系,对邯邢铁矿区斑状石英二长岩中角闪石斑晶环带结构进行了成因矿物学研究.通过角闪石温度计、压力计、氧逸度计和湿度计的计算,发现岩浆在14km深处岩浆房内经过多次岩浆混合过程,其后演化的岩浆侵位到1.9 km的深度.岩浆房的温度为935～964℃,氧逸度为△NNO+0.27～△NN...  相似文献   

Three types of 2-degree field compensating atmospheric dispersion correctors for prime focus     

Xu Wen-li  Wang Ya-nan 《Chinese Astronomy and Astrophysics》1993,17(4):464-472

Three types of prime focus correctors for Chinese 2.16m telescope are introduced in this paper. Each corrector has a 2 degree field and can be used to compensate the atmospheric dispersion of 6″. All the three correctors have excellent image quality and the angles between the principal rays and the optical axes are quite small. There is no special technological difficulty in their fabrication. These designs can not only be used in the 2.16m telescope but also be applied to other large telescopes.  相似文献   

孤岛油田南区馆1+2砂层组细分对比标志特征   总被引：1，自引：0，他引：1  

乐大发  陈清华  张福利 《地球科学与环境学报》2011,33(1):84-88

基于沉积学和储层地质学理论,以孤岛油田南区馆1+2砂层组高弯曲流河沉积为例,充分利用密井网条件下的测井资料,研究储层细分对比中的标志类型、特征、分布及其应用。首先,介绍了馆1+2砂层组的测井响应、地震反射等宏观特征;接着,利用感应电导率曲线、自然电位曲线的响应特征寻找细分对比标志;然后,将选取的标志联合使用得到孤岛油田南区馆1+2砂层组的顶面构造图。结果表明:研究区缺少全区性标志,但存在局部性标志;局部性标志有泥岩类、砂岩类、"钙质尖"类、砂泥组合类等4类;泥岩类标志表现出高感应电导率特点,砂岩类标志表现为低电阻率,自然电位曲线呈"箱形"或小型的"钟形","钙质尖"类标志表现为高电阻、高微电阻、低声波时差,低自然电位值的尖锋,砂泥组合类标志表现为感应曲线特征的可对比性强;泥岩类和砂岩类标志分布面积较大,呈局部连片状;"钙质尖"类和砂泥组合类标志分布面积较小,呈条带状;上述4类标志在平面上的叠合分布完全覆盖研究区。总之,充分利用好局部性标志,同样能够很好地进行类似地区的储层细分对比。  相似文献   

A COMPARISON AND EVALUATION OF TWO CENTENNIAL-SCALE SEA SURFACE TEMPERATURE DATASETS IN THE CHINA SEAS AND THEIR ADJACENT SEA AREAS     

王庆元  李琰  李清泉  王亚男 《热带气象学报(英文版)》2018,24(4):448-456

Two reconstructed sea surface temperature(SST) datasets(HadISST1 and COBE SST2) with centennial-scale are compared on the SST climate change over the China Seas and their adjacent sea areas. Two independent datasets show consistency in statistically significant trends, with a warming trend of 0.07—0.08 ℃ per decade from 1890 to2013. However, in shorter epochs(such as 1961—2013 and 1981—2013), HadISST1 exhibits stronger warming rates than those of COBE SST2. Both datasets experienced a sudden decrease in the global hiatus period(1998—2013), but the cooling rate of HadISST1 is lower than that of COBE SST2. These differences are possibly caused by the different observations sources which are incorporated to fill with data-sparse regions since 1982. Different data sources may lead to higher values in HadISST1 from 1981 to 2013 than that in COBE SST2. Meanwhile, the different data sources and bias adjustment before the World War II may also cause the large divergence between COBE SST2 and HadISST1,leading to lower SST from 1891 to 1930. These findings illustrate that the long-term linear trends are broadly similar in the centennial-scale in the China Seas using different datasets. However, there are large uncertainties in the estimate of warming or cooling tendency in the shorter epochs, because there are different data sources, different bias adjustment and interpolation method in different datasets.  相似文献   

中国北方草地植物群落碳、氮元素组成空间变化及其与土壤地球化学变化的关系   总被引：5，自引：1，他引：4  

程建中  李心清  刘钟龄  胡璐  黄代宽 《地球化学》2008,37(3):265-274

碳、氮元素是土壤中的关键元素.在我国黄土高原北部-宁夏中东部处于荒漠化初期阶段的草地中,土壤的碳、氮元素组成出现了异乎寻常的特征,即相对于碳含量,氮含量异常偏低.认识造成这一现象的原因对我国北方草地的保护和重建具有重要意义.植被的输入是土壤中碳、氮元素组成的最为重要的控制因素之一.为认识植被碳、氮含量的空间变化对上述现象产生的贡献,对包括草地碳、氮异常区在内的区域进行了沿线植物群落的化学组成研究.结果表明:1.植物群落平均碳含量约为40%～50%,不同植物群落类型碳含量以苦豆子、达乌里胡子枝群落最高(44.225%),蛛丝蓬、骆驼蓬群落最低(35.516%).绝大多数植物群落平均氮含量约为2%～4%,不同植物群落类型含氮量以猪毛菜、星状角果藜群落最高(4.482%),蛛丝蓬群落最低(1.356%);2.植物群落生物量空间分布与对应降雨量变化趋势一致,说明降雨量是限制群落地理分布的关键因子;3.植物群落与土壤C/N比值随纬度呈现不一致的变化规律,相关分析表明,两者呈现统计学上的显著负相关关系,相关系数为:r=-0.392(P＜0.05,n=32).上述结果表明,在研究地区荒漠化初期阶段的草地中,植被输入不是引起该区域土壤C/N异常升高的原因.  相似文献   

利用GPS可降水量校正MODIS近红外水汽数据   总被引：1，自引：0，他引：1  

方圣辉  毕创  乐源  裴鉴 《测绘科学》2016,41(9):38-41

针对MODIS近红外水汽产品精度不足以及地基GPS技术解算的大气可降水量地理分布不连续的问题,提出一种利用地基GPS可降水量来校正MODIS水汽产品从而得到区域性连续分布的高精度可降水量的方法。利用GAMIT软件和地基GPS数据解算出IGS站点的大气水含量,建立GPS可降水量与MODIS近红外水汽产品的回归分析模型得到最终的校正结果。通过与实测气象站数据对比分析可知,所提方法有效地结合了MODIS和地基GPS两种遥感水汽技术的优点,能够得到高精度、地理分布连续的大气可降水量,研究结果可为实时天气预报、气候监测等工作提供参考。  相似文献   

Morphological Evolution and Its Response to the Navigational Improvements in the North Passage,Yangtze Estuary     

刘杰  陈吉余  徐志扬  乐嘉海 《中国海洋工程》2007,21(4):611-624

By use of bathymetric chart,recent change of the riverbed in the North Passage of the Yangtze Estuary has been studied in this paper.The main channel of the upper,middle and lower(section)in the North Passage has been successively eroded and its groin field significantly deposited.At the same time,sediment has been deposited on the entrance region.Erosion and deposition had responded rapidly to the construction of the regulation engineering.There was about one year duration of lagging between erosion in the deep channel and the construction of the regulation engineering.The siltation lag of time in the groin field varied with the initial depth,but the average deposited thickness was about 0.5 m per year.Volumetric analysis demonstrates that there is a increasing trend of siltation in the North Passage after 2002,because of the difference in duration and quantity between erosion in the deep channel and deposition in the groin field.The water volume of the North Passage was reduced by ≈9%(280 million m3)between 2002 and 2006.Sediment budget reveals that the main sediment deposited in the North Passage takes its source from the river and the ocean.The decreasing water volume was attributable to shoaling in the groin field.Its triggering factors for increased sedimentation are the navigational improvements(jetties and groins)after 1998,which altered the passage boundary and destroyed the equilibrium state on the average ebb and flood sediment fluxes.The establishment of a stable estuary is attributed to a reduction in depth of the groin field.The forecast on the sediment deposition quantity and continuous infilling time in the groin system is about 325×106m3 and 6～7 years,respectively.  相似文献