Feasibility Study of In-Well Vapor Stripping Using Airlift Pumping     

Haim Gvirtzman  Ori Gonen 《Ground Water Monitoring & Remediation》1995,15(4):155-162

This study tests the feasibility of an aquifer remediation concept proposed by Gvirtzman and Gorelick (1992) that involves the removal of volatile organic compounds (VOCs) dissolved in ground water. The principal is 10 inject air into a well, creating airlift pumping, which is used as a means of in-well vapor stripping. The partially treated water is diverted away from the well and infiltrates back to the water table, thus allowing remediation of a larger aquifer volume.
A remediation well prototype, constructed in a laboratory aquifer model, was used to demonstrate the processes involved. The removal rates of trichloroethylene, toluene, and chloroform were monitored using eight triple-level observation wells. The continuous decrease of VOC concentrations during the short-term experiment has yielded macroscopic evidence that the process offers some promise. It was found that the flow field in the saturated zone. involving the continuous water circulation between the pumping well and the recharging area, caused temporal and spatial variation in remediation efficiency.  相似文献   

Desertification in Northern Sinai in the eighteenth century     

Haim Tsoar 《Climatic change》1995,29(4):429-438

Several natural and anthropogenic phenomena in the northern Sinai sand sea and the northern Negev desert were caused by desiccation of the area during most of the 17^th and the 18^th century. The dry phase had been preceded by a wet period. It appears that the combination of several wet decades followed by a long period of desiccation was the cause of desertification processes in the area which then triggered the destruction of vegetation.There is some congruity between the wet period and the period of maximum sunspot activity, known as theMedieval Maximum, while the desiccation of the area which followed coincided approximately with the period of minimum solar activity, known as theMaunder Minimum.  相似文献   

The distribution of Autumnal Easterly Wind Spells Favoring Rapid spread of forest wildfires on Mount Carmel,Israel     

Haim Kutiel dr.  Pua Kutiel dr. 《GeoJournal》1991,23(2):147-152

Wildfires became a severeecological and financial problem in Israel during the last few years. A significant increase in the incidence of severe wildfires in natural shrublands and planted forests as arson was observed. On 19–20. 9. 89 a large wildfire ignited as an act of terrorism, devastated large parts of Mt. Carmel forests.Weather conditions during a wildfire have an important role in the determination of the rate of spread of the fire. This depends mainly on the availability of dry matter and the wind speed. Two factors that reach their optimum at the end of the summer in September and October during Sharav episodes. The distribution of easterly wind spells associated with Sharav events is considered. The results show that there is no climatic limitation to a spread of a wildfire of the same order of magnitude as the last one, every year.  相似文献   

Temporal segregation in co-existing Acomys species:the possible role of nest site     

A. Haim  F.M. Rozenfeld 《Journal of Arid Environments》1995,29(4)

The co-existence of two species of spiny mouse of the genus Acomys is possible due to temporal segregation. While the common spiny mouse A. cahirinus is nocturnal, the golden spiny mouse A. russatus is diurnal when occurring with the former. An attempt was made to investigate the role of nest site as an environmental resource for competition between these two species. Nine heterospecific pairs of mice of both the same or opposite sexes were tested using an observation pen with two nesting places attached to each side. Each pair tested was observed in the pen over a period of 48h. In eight out of the nine different pairs, A. cahirinus occupied the original nest site of A. russatus. The replacement was found to be not random. The results of this study show that A. cahirinus selects a preferred nest site and its vacated nest sites can be utilized by A. russatus.  相似文献   

Biased monitoring of fresh water-salt water mixing zone in coastal aquifers   总被引：2，自引：0，他引：2  

Shalev E  Lazar A  Wollman S  Kington S  Yechieli Y  Gvirtzman H 《Ground water》2009,47(1):49-56

In coastal aquifers, significant vertical hydraulic gradients are formed where fresh water and underlying salt water discharge together upward to the seafloor. Monitoring boreholes may act as "short circuits" along these vertical gradients, connecting between the higher and the lower hydraulic head zones. When a sea tide is introduced, the fluctuations of both the water table and the depth of the mixing zone are also biased due to this effect. This problem is intensified in places of long-screen monitoring boreholes, which are common in many places in the world. For example, all approximately 500 boreholes of the fresh water-salt water mixing zone in the coastal aquifer of Israel are installed with 10 to 50 m long screens. We present field measurements of these fluctuations, along with a three-dimensional numerical model. We find that the in-well fluctuation magnitude of the mixing zone is an order of magnitude larger than that in the porous media of the actual aquifer. The primary parameters that affect the magnitude of this bias are the anisotropy of the aquifer conductivity and the borehole hydraulic parameters. With no sea tide, borehole interference is higher for the anisotropic case because the vertical hydraulic gradients are high. When tides are introduced, the amplitude of the mixing zone fluctuation is higher for the isotropic case because the overall effective hydraulic conductivity is greater than the conductivity in the anisotropic case. In the aquifer, the fresh water-salt water mixing zone fluctuations are dampened, and tens of meters inland from the shoreline, the fluctuations are on the order of few centimeters.  相似文献   

Geological and pedological aspects of an Early-Paleolithic site: Revadim,Central Coastal Plain,Israel     

Gdaliahu Gvirtzman  Moshe Wieder  Ofer Marder  Hamudi Khalaily  Rivka Rabinovich  Hagai Ron 《Geoarchaeology》1999,14(2):101-126

An Early Paleolithic site was recently discovered within a sequence of paleosols in the Revadim Quarry, central coastal plain of Israel. The section is composed of three superimposed soils in a continuous sequence, but separated by two unconformity surfaces. The uppermost paleosol is a modern Dark Brown Grumusol (Vertisol), the middle is a Quartzic Gray Brown Soil (Haploxeralf), and the lower is a Red Hamra (Rhodoxeralf). Normal magnetic polarity was detected in the two lower soils, indicating that they are younger than the Brunhes–Matuyama boundary (<780 ka). A human occupation bed, enriched in secondary carbonate nodules, forms the lower part of the Quartzic Gray Brown Soil and overlies the Red Hamra. The living floor is located on top of the unconformity surface, separating the Red Hamra from the overlying Quartzic Gray Brown Soil. Middle to Late Acheulian handaxes, choppers, cores, and flake tools, including tools made by the Levallois technique, and man-laid flint pebbles were excavated in the human occupation bed. In addition, two elephant tusks, an elephant pelvis, an elephant tooth (Palaeoloxodon antiquus), tusk splinters, and bones of equid, suid, cervid, bovid, felid, and rodents were also collected. Based on well-documented nearby boreholes and on regional correlation, it appears that the underlying dune sands, the parent materials from which the Red Hamra developed, were deposited probably during a phase of high-stand sea level of Isotope Stage 9. The Red Hamra developed simultaneously with the human occupation of the site, probably during a phase of low-stand sea-level of Isotope Stage 8, before some 300–245 ka. The overlying dune sands, the parent materials from which the Quartzic Gray Brown Soil developed, were deposited probably during a phase of high-stand sea level of Isotope Stage 7. The climate prevailing in the area during Stage 8, as well as during the human habitation, was moist, with a dense vegetation cover of grassland and probably scattered trees. A small lake of trapped fresh water at a junction of two small tributaries of the Soreq River drainage system near the area occupied was available to hominids and animals. © 1999 John Wiley & Sons, Inc.  相似文献