茅尾海入海河口池塘养殖污染状况遥感调查     

胡义强  杨骥  荆文龙  彭小燕  蓝文陆  彭梦微  张雨萌 《测绘通报》2022,(7):12

针对广西茅尾海入海河口池塘养殖污染问题,本文利用无人机多光谱遥感影像和实测水质数据,建立了反映水体营养状态的叶绿素a (Chl-a)、化学需氧量(COD)、悬浮物(SS)、总氮(TN)、总磷(TP)5种水质参数,反演光谱特征及遥感反演模型,并利用湖泊综合营养指数法对水体富营养化状态进行评价。研究结果表明:①Chl-a与蓝、近红外波段相关性显著,COD与红、红边波段相关性显著,SS与红边波段相关性显著,TN与近红外波段相关性显著,TP与蓝、绿波段相关性显著;②在建立的几种水质参数反演模型中,二次多项式函数反演模型综合效果最佳;③池塘养殖区水体富营养指数多集中在60～80,属于中度和重度富营养化程度,且近岸水体富营养化程度大多低于远岸。  相似文献   

Lithium Extraction from Carbonate-type Saline Lake by Utilizing of Geothermal Solar Pond in Tibet     

YU Jiangjiang  ZHENG Mianping  WU Qian  NIE Zhen  BU Lingzhong 《《地质学报》英文版》2014,88(Z1):389-390

正1 Introduction The geothermal solar pond is a kind of special solar pond.It is different from traditional solar pond,which high temperature geothermal water can be used to heat brine.When the salt in the brine reaches saturation temperature,it precipitate out and is separated from the brine.Compared with solar pond,the geothermal solar pond does not rely entirely on solar radiation as a heat  相似文献   

新疆西南天山拜什塔木地区苏维依组物源区及沉积环境探讨          下载免费PDF全文

唐小东  妥小双  米登江  秦海峰 《地质找矿论丛》2014,29(4):579-586

新疆西南天山拜什塔木地区的古近系渐新统苏维依组（E3s）是拜什塔木铜矿赋矿层位.文章通过对苏维依组的岩石化学、微量元素地球化学、稀土元素地球化学特征研究,认为其物源区环境为靠近活（被）动大陆边缘区;粒度分析表明沉积环境与海滨砂瀉湖砂、河流砂、沙丘砂等环境相近;盐度分析、氧化-还原分析、气候指数研究分析表明,苏维依组属于干热海退咸化湖相沉积.  相似文献   

基于科学知识图谱的水文化变迁研究方法探析简     

Xiong Yonglan  Zhang Zhiqiang  Wei Yongping  Liu Zhihui  Cheng Guodong 《地球科学进展》2014,29(1):92-103

Cultural transformation (including knowledge innovation, ideological emancipation and slogan publicity, etc.) is one of the most important drivers of changes in water management policies. Earlier studies into water culture were mainly based on qualitative methods. However, using only qualitative methods, it is difficult to reveal the stage characteristics of water culture evolution objectively and accurately. Mapping knowledge domains, a rising knowledge discovery method, can holistically reveal the sources of knowledge and the laws of its development. This paper is devoted to exploiting its potential as a quantitative method for researches targeting at water culture evolution. By extracting the key words related to water from People’s Daily, knowledge domains on water culture evolution in China during 1946 2012 are mapped and interpreted, based on which the water culture evolution is unveiled. By comparing the water culture evolution with changes in water policies, stages of water resource development and extreme hydrological events, it is found that there exist clear relationships. This convinces us that mapping knowledge domains could play an effective role in quantitative research on water culture evolution. Further steps towards better quantitative researches on water culture evolution using this method include the enhancement of the universality of newspapers, improvement on the accuracy of key words extraction, and increase in the precision of visualization analysis.  相似文献   

板块运动规律梳理及其源动力实验计算研究     

方曙 《大地测量与地球动力学》2021,41(6):551-560

洋中脊是大洋的胚胎,从洋中脊为地堑式中央裂谷的形态特征来看,大洋是拉张应力的产物,因此必须依据大陆漂移造成海底被动扩张这一结论来分析研究板块运动的动力源问题。大陆漂移的方向是有规律的,根据世界大洋年龄图等资料进行逆推,还原不同阶段的洋陆展布状态,可以看出,白垩纪以来南半球大陆分解向北运动、北半球大陆分解向南运动,大陆在向低纬度地区运动的过程中向西运动,这种大陆漂移的方向性特征与地球自转力作用的方向性特征完全吻合。根据模拟实验,在空心不锈钢球体的中高纬度表面吸附具有一定质量的磁扣并旋转不锈钢球体,当达到一定转速时,磁扣会向赤道漂移,同时向西漂移。同理,地球上的大陆高出大洋,当中高纬度的大陆自转离极力大于前方大洋阻力时,必然会造成大陆在大洋之上仰冲,也就是大陆在大洋之上漂移。根据离极力理论计算可知,中心在中纬度的大陆产生的离极力足以使前方大洋破裂屈服,从而发生指向赤道方向的逆冲运动;而向赤道运动的大陆因旋转半径变大会产生强烈的向西的同步力,造成大陆西侧大洋破裂并发生逆冲运动,从而向西漂移。板块运动的本质就是大陆挤压大洋造成洋壳破裂逆冲,陆壳于洋壳之上作仰冲运动,大陆前方的古大洋逐渐被俯冲消亡,最终与前方大陆碰撞造山合并成新的大陆;而由于大陆的前行造成其后的岩石圈普遍处于张裂状态,导致原大陆被拉张分解为2个或多个陆块,分裂的陆块之间沿洋中脊增长生长为新大洋。地球自转形成的地转力除造成板块运动外,还可能使岩石圈内部发生断裂,并在已有断裂上积累和释放势能,从而造成地震。  相似文献   

Puhimau Thermal Area: A Window into the Upper East Rift Zone of Volcano, Hawaii?     

K. A. McGee  A. J. Sutton  T. Elias  M. P. Doukas  T. M. Gerlach 《Pure and Applied Geophysics》2006,163(4):837-851

We report the results of two soil CO₂ efflux surveys by the closed chamber circulation method at the Puhimau thermal area in the upper East Rift Zone (ERZ) of volcano, Hawaii. The surveys were undertaken in 1996 and 1998 to constrain how much CO₂ might be reaching the ERZ after degassing beneath the summit caldera and whether the Puhimau thermal area might be a significant contributor to the overall CO₂ budget of . The area was revisited in 2001 to determine the effects of surface disturbance on efflux values by the collar emplacement technique utilized in the earlier surveys. Utilizing a cutoff value of 50 g m⁻² d⁻¹ for the surrounding forest background efflux, the CO₂ emission rates for the anomaly at Puhimau thermal area were 27 t d⁻¹ in 1996 and 17 t d⁻¹ in 1998. Water vapor was removed before analysis in all cases in order to obtain CO₂ values on a dry air basis and mitigate the effect of water vapor dilution on the measurements. It is clear that Puhimau thermal area is not a significant contributor to CO₂ output and that most of CO₂ (8500 t d⁻¹) is degassed at the summit, leaving only magma with its remaining stored volatiles, such as SO₂, for injection down the ERZ. Because of the low CO₂ emission rate and the presence of a shallow water table in the upper ERZ that effectively scrubs SO₂ and other acid gases, Puhimau thermal area currently does not appear to be generally well suited for observing temporal changes in degassing at .  相似文献   

Numerical theory of rotation of the deformable Earth with the two-layer fluid core. Part 2: Fitting to VLBI data     

G. A. Krasinsky  M. V. Vasilyev 《Celestial Mechanics and Dynamical Astronomy》2006,96(3-4):219-237

VLBI-based offsets of the Celestial Pole positions, as well as the variations of UT (series of Goddard Space Flight Center, 1984–2005) are processed applying the Earth’s rotation theory (ERA) 2005 constructed by the numerical integration of the differential equations of rotation of the deformable Earth. The equations were published earlier (Krasinsky 2006) as the first part of the work. The resulting weighted root mean square (WRMS) errors of the residuals , for the angles of nutation and precession are 0.136 and 0.129 mas, respectively. They are significantly less than the corresponding values 0.172 and 0.165 mas for the IAU 2000 model adopted as the international standard. In ERA 2005, the angles , are related to the inertial ecliptical frame J2000, the angle including the precessional secular motion. As the published observational data are theory-dependent being related to IAU 2000, a procedure to confront the numerical theory to the observed Celestial Pole offsets and UT variations is developed. Processing the VLBI data has shown that beside the well known 435-day FCN mode of the free core nutation, there exits a second mode, FICN, caused by the inner part of the fluid core, with the period of 420 day close to that of the FCN mode. Beatings between the two modes are responsible for the apparent damping and excitation of the free oscillations, and are implicitly modeled by ERA 2005. The nutational and precessional motions in ERA 2005 are proved to be mutually consistent but only in case the relativistic correction for the geodetic precession is applied. Otherwise, the overall WRMS error of the residuals would increase by 35%. Thus, the effect of the geodetic precession in the Earth rotation is confirmed experimentally. The other finding is the reliable estimation δ_c = 3.844 ± 0.028° of the phase lag δ_c of the tides in the fluid core. When processing the UT variations, a simple model of the elastic interaction between the mantle and fluid core at their common boundary made it possible to satisfactory describe the largest observed oscillations of UT with the period of 18.6 year, reducing the WRMS error of the UT residuals to the value 0.18 ms (after removing the secular, annual and semi-annual terms).  相似文献   

Audouin's gull chicks as bioindicators of mercury pollution at different breeding locations in the western Mediterranean     

Sanpera C  Moreno RO  Ruiz X  Jover L 《Marine pollution bulletin》2007,54(6):691-696

Mercury levels of Audouin's gull are amongst the highest for Mediterranean seabirds, and have been mainly attributed to its piscivorous habits in these naturally Hg rich waters. Moreover, two additional factors could enhance its mercury intake: the consumption of discarded fish (which attain higher concentrations) and/or feeding in areas receiving Hg anthropogenic inputs. In order to differentiate the relevance of both sources we analysed Hg and stable isotopes of chick feathers from different breeding locations in western Mediterranean: one in its northern part (Ebro Delta) and two southern (Chafarinas Isl. and Alborán Isl.). The results from stable isotopes indicate that consumption of discards is higher at Alborán Isl., followed by the Ebro Delta and Chafarinas Isl. Thus, the higher mercury levels found in the Ebro Delta cannot be explained uniquely by the contribution of discarded fish to diet, but local pollution caused by the river Ebro waters accounts for Hg differences observed.  相似文献   

BLLac天体ON231的光变周期研究     

徐云冰  张雄  李孝攀  董富通 《云南天文台台刊》2010,(4):283-289

从大量文献中收集了BLLac天体ON231光学B波段约100年的观测数据,在此基础上分析了光变周期。用两种不同的方法（Jurkevich方法和小波分析法）分析周期光变,发现其光变曲线中存在13．6±1．5及26．1年的周期。  相似文献   

Modelling the effect of temperature on unsaturated soil behaviour     

Matthieu Dumont  Said Taibi  Jean-Marie Fleureau  Nabil Abou Bekr  Abdelghani Saouab 《Comptes Rendus Geoscience》2010,342(12):892-900

A simple thermohydromechanical (THM) constitutive model for unsaturated soils is described. The effective stress concept is extended to unsaturated soils with the introduction of a capillary stress. This capillary stress is based on a microstructural model and calculated from attraction forces due to water menisci. The effect of desaturation and the thermal softening phenomenon are modelled with a minimal number of material parameters and based on existing models. THM process is qualitatively and quantitatively modelled by using experimental data and previous work to show the application of the model, including a drying path under mechanical stress with transition between saturated and unsaturated states, a heating path under constant suction and a deviatoric path with imposed suction and temperature. The results show that the present model can simulate the THM behaviour in unsaturated soils in a satisfactory way.  相似文献