A study of thirteen geothermal springs located in the geothermal field of Guelma, northeastern Algeria, was conducted. Samples were collected during the period between January 2014 and February 2016. Geochemical processes responsible for the chemical composition of thermal and mineralized water were evaluated. The hydrochemical analysis shows that the thermal waters are characterized by the presence of two different chemical facies, the first type SO4–Ca in the east, west and south of Guelma, the second type HCO3–Ca in the south. This analysis also attributed to sodium, chlorides, and sulfates to an evaporitic terrigenous origin by the molar ratio Sr2+/Ca2+. The thermal spring waters from Guelma geothermal system have a meteoric origin, and all samples are immature with strong mixing between hot and shallow waters with 19–38.5% rate of mixing. The silica geothermometer shows that these thermal waters have a temperature varying from 84 to 122 °C and that the water came from a depth of 2100–3000 m through a fault system that limits the pull-apart basin of Guelma. Potential environmental effluent from thermal spas could pollute in both the irrigation and drinking waters, and which imposes danger on the health of the inhabitants of the region.
We construct a U-N secular canonical planetary theory of the third order with respect to planetary masses. The Hori-Lie procedure is adopted to solve the problem. Expansions have been carried out by hand, neglecting powers higher than the second with respect to the eccentricity-inclination. We take into account the principal as well as the indirect part of the planetary disturbing function. The theory is expressed in terms of the Poincaré canonical variables, referring to the Jacobi-Radau set of origins. We assume that the 1:2 U-N critical terms and its multiples are the only periodic terms. 相似文献
We generalize our results of a second order Jupiter-Saturn planetary theory to be applicable for the case of the four major planets.We use the Von Zeipel method and we neglect powers higher than the third with respect to the eccentricities and sines of the inclinations in our expansions. We consider the critical terms as the only periodic terms. 相似文献
The earliest gravity measurements in Egypt were carried out by the Anglo-Egyptian Oil Company using Holweck-Lejay pendulum in the period 1937–1940.The measurement comprised few stations (about 41) in restricted areas along both the Western and Eastern coasts of the Gulf of Suez.During the period 1950–1951 Prof. G. Woolard made 21 gravimetric measurements in Egypt as a part of the world-wide gravity base net. Thi was refeered to Potsdam absolute value which was considered as the World Gravity Datum.In 1974, a new world-wide gravity net was published (I.G.S.N.71) which introduced a new concept for the world gravity reference datum, and consequently has replaced the Potsdam System. Since then, it was recommended that a national gravimetric network of base stations in Egypt on the basis of the I.G.S.N.-71 be established within the frame of establishing a gravity map of Egypt.In the period from January 1975, The General Petroleum Company carried out 624 gravity observations throughout the country. These measurements have been combined with the I.G.S.N.-71 values to form 65 gravity base points which in turn from the N.G.S.B.N. (Fig. 1). 相似文献
The Grombalia aquifer (NE Tunisia) is an example of an important source of water supply for regional and national development, where the weak controls over abstraction, fertilizer application and waste disposal, coupled with limited knowledge of aquifer dynamics, is causing aquifer over-exploitation and water quality degradation. Assessing the key role of groundwater in water-resources security is therefore of paramount importance to support new actions to preserve water quality and quantity in the long-run. This study presents one of the first investigations targeted at a complete assessment of aquifer dynamics in the Grombalia aquifer. A multi-tracer hydrogeochemical and isotopic (δ2H, δ18O and 3H) approach was used to study the influence of seasonal variation on piezometric levels, chemical and isotopic compositions, and groundwater recharge. A total of 116 samples were collected from private wells and boreholes during three periods in a 1 year monitoring campaign (February–March 2014, September 2014 and February 2015). Results revealed the overall unsuitability of groundwater for drinking and irrigation purposes (NO3?>?50 mg/L in 51% of the wells; EC >1,000 μS/cm in 99% of the wells). Isotopic balance coupled to piezometric investigation indicated the contribution of the shallow aquifer to deep groundwater recharge. The study also revealed the weakness of ‘business as usual’ management practices, highlighting possible solutions to tackle water-related challenges in the Grombalia region, where climate change, population growth and intensive agricultural activities have generated a large gap between demand and available water reserves, hence becoming a possible driver for social insecurity. 相似文献
Statics are an effective approach to correct for complex velocity variations in the near surface, but so far, to a large extent, a general and robust automatic static correction method is still lacking. In this paper, we propose a novel two‐phase automatic static correction method, which is capable of handling both primary wave statics (PP statics) and converted‐wave statics (S‐wave statics). Our method is purely data driven, and it aims at maximizing stacking power in the target zone of the stack image. Low‐frequency components of the data are analysed first using an advanced genetic algorithm to estimate seed statics and the time structure for an event of interest, and then the original full‐band data are further aligned via the back‐and‐forth coordinate descent method using the seed statics as initial values and the time structure for event alignment guidance. We apply our new method to two field datasets, i.e., one for 2D PP static correction and the other for 3D S‐wave static correction. 相似文献
This paper reveals the contingent aspect associated with the actualization of a neoliberal space. The paper examines the material, institutional, and economic conditions necessary for a neoliberal agenda to transform its urban policy objectives into a material reality. The study follows changes in housing conditions in Santa Monica, California from 1990 to 2008. During this period, the confluence of three sets of events led to the actualization of a neoliberal space. First, housing damage from the 1994 Northridge earthquake removed “dead capital” from the housing sector. Second, subsequent administrative actions at the local level and more importantly deregulation legislation at the state level eliminated rent control regulations and created market incentives that favored upscale development. Finally, the state’s economic recovery generated a substantial flow of private investments into the real estate market. These combined factors led not only to the dismantling of affordable housing in Santa Monica, but also to the erosion of residents’ and local authorities’ ability to manage housing choices and, consequently, to a historic restructuring of Santa Monica’s physical and social space. These changes had a disproportionately and negative effect on low-income and minority renters. 相似文献
As in many other semi-arid regions, the Plio-quaternary aquifer of the eastern coast of Cap Bon peninsula (NE Tunisia) shows
a parallel increase in overexploitation and mineralization of groundwater resources and so the water quality is deteriorating.
Different methods using geochemistry (ions Na+, Cl−, Ca2+, Mg2+, Br−) and stable isotopes (18O, 2H) are compared with the hydrodynamic information for identifying the main processes involved in the increase of salinization.
Along the coast, intrusion of seawater resulting from groundwater overexploitation is identified, but is not the only cause
of qualitative degradation: the development of irrigation that induces soil leaching and transfer of fertilizers to groundwater
over the whole aquifer extent is another major reason for the increase in salinization. A total of 48 groundwater wells were
sampled to obtain additional information on the hydrochemical characteristics of the groundwater defined in previous studies. 相似文献
Climate aridity and intensive exploitation due to uncontrolled pumping for irrigation have caused a drastic decrease in the piezometric level of the shallow aquifer of Chougafiya plain, central Tunisia, and have seriously degraded groundwater quality. According to the hydrochemical data (Cl?, SO42?, NO3?, HCO3?, Br?, Na+, Mg2+, K+, Ca2+, Sr2+) and the stable isotopes (18O and 2H content), groundwater salinization in the investigated aquifer is caused by four main processes: (1) evaporite dissolution (2) cation exchange reactions (3) evaporation processes and (4) mixing with Sabkhas salt water causing salinity to increase in the central and southern parts of the basin. The radiogenic (3H) isotope data provided insight into the presence of significant contemporaneous recharge waters in the western part of the shallow aquifer. The movement of the tritiated water may have occurred according to the general flow path (NW–SE). When tritium was used in conjunction with the stable isotopes and chloride, the mixing process could be clearly identified, especially in the central part of the study area. 相似文献