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201.
Sattam Almadani Hussain Alfaifi Abdullah Al-Amri Mohamed Fnais Elkhedr Ibrahim Kamal Abdelrahman Mohammed Shehata Faisal Zaidi 《Arabian Journal of Geosciences》2017,10(6):139
This study was carried out in the Alwadeen area of Khamis Mushayt district of southwestern Saudi Arabia to evaluate the hydrochemical characteristics of the shallow hard rock aquifers. These hard rock aquifers mostly comprise granites and contain significant quantities of groundwater that complement the available groundwater from the unconsolidated alluvial sediments in the nearby wadis. The field investigation indicates two main fracture sets which intersect each other and are oriented in the west-northwest and east-west directions. The granitic rocks in the area are intruded by coarse-grained and quartz-rich monzogranite and pegmatite veins. Hydrogeologically, the fracture systems are important since they facilitate the groundwater storage and assume the transmissive function during times of groundwater abstraction. Given the fact that groundwater in the fractured rock aquifers generally occurs at shallow depths, it may be exposed to contamination from surface and/or near-surface sources, and it is therefore important to evaluate its quality. To this end, a hydrochemical analysis was carried out on six groundwater samples collected from the area. The hydrochemistry revealed that the groundwater is fairly fresh, and facies analysis reveals mixed Na-Cl and Ca-Mg-Cl-SO4 types. Overall, the results reveal that the groundwater is saturated with calcite and dolomite, but unsaturated with gypsum and halite. The degree of salinity increases in the direction of the groundwater flow due to increased rock-water interaction. 相似文献
202.
In Meghalaya, northeast India, the local people have the tradition of managing forest resources since early ages. The management practice varies and there are forests with high degree of protection, where no extraction (sacred forests) is allowed. There are also forests with moderate- level of protection and -extraction (reserved forests) as well as forests with low level of protection and open extraction (village forests). The present study was conducted to understand the impact of this traditional management system on the level of human disturbance, and on community composition and structure of the forests in Khasi hills of Meghalaya. The result revealed that disturbance index was low, whereas species richness, density and basal cover were significantly high in forests with high degree of protection (sacred forest) than those with low protection (reserved and village forest). Majority of endemic and threatened plant species were restricted to sacred forests as compared to the other forest types. Though these practices have ensured the sustainable use of forest resources by the local people but due to increased human- pressure and -disturbances, more effective conservation strategies need to be undertaken. Therefore, providing alternatives for fuel Received: 28 July 2016 Revised: 1 October 2016 Accepted: 15 December 2016 wood to local people, environmental education, encouraging afforestation and developmental activities involving local communities are recommended. 相似文献
203.
Factors Influencing the Atmospheric Depositional Fluxes of Stable Pb, 210Pb, and 7Be into Chesapeake Bay 总被引:3,自引:0,他引:3
Guebuem Kim N. Hussain J. R. Scudlark T. M. Church 《Journal of Atmospheric Chemistry》2000,36(1):65-79
Atmospheric depositional fluxes of 7Be and210Pb (bulk) and stable Pb (wet) were measuredsimultaneously for one year (from September 1995–August 1996) atStillpond, Maryland on the uppereastern shore of the Chesapeake Bay. The annual total(bulk) depositional fluxes of 210Pb and 7Bewere 0.78 and 13 dpm cm-2, respectively, andagree well with other previously reported results atnearby locations such as Norfolk, VA and Lewes, DE. The wet depositional flux of stable Pb (58 ng cm-2 yr-1)was also similar to thatmeasured at other Chesapeake sites during 1990–1991(55 ng cm-2 yr-1, for both Wye and Elms,Maryland). This suggests that a constant Pb flux hasbeen reached since the mandatory use of unleadedgasoline was instituted. The concentrations of7Be, 210Pb, and to a lesser extent stable Pbwere diluted exponentially by precipitation, based onconcentrations versus precipitation plots. Due tohigher enrichment of 210Pb in the lowertroposphere, the dilution effect was largest on210Pb (i.e., controlled mainly by below-cloudscavenging processes), and thus its depositional fluxincrease is negligible as precipitation amountincreases. A good correlation between the amount ofprecipitation and total depositional flux of 7Beand stable Pb, which are more enriched in the uppertroposphere, suggests that precipitation amount isimportant in controlling their fluxes (i.e.,controlled by both below-cloud scavenging and in-cloudcondensation processes). Based on 7Be versus210Pb plots, it appears that 7Be, relativeto 210Pb, is less efficiently scavenged bysnowfall. Our results suggest that in addition toprecipitation amounts, marine air-mass transport orsnowfall may be important factors in controlling theseasonal variability of the fallout fluxes of tracemetals in coastal areas. 相似文献
204.
Syed Nadeem Hussain Bokhari Thomas C. Meisel 《Geostandards and Geoanalytical Research》2017,41(2):181-195
This work provides a measurement procedure for the complete digestion of rock samples containing refractory minerals such as zircon and chromite. Their dissolution by wet acid digestion is often incomplete but, although providing complete digestions, alkali fusion techniques can result in solutions with a high blank and total dissolved solid content. It was established by the systematic study with reference material trachyandesite MTA‐1 that a 1:6 sample to sodium peroxide (Na2O2) ratio is conservative for the complete digestion and recovery of all the analytes especially those contained in zircon. The sample decomposition time was 120 min for the zircon‐bearing rhyolite reference material MRH‐1. Complete digestion of chromite was obtained in the harzburgite RM MUH‐1. The sample solutions were stable for at least 1 year. Accurate measurements of SiO2, Al2O3, TiO2, P2O5 and K2O could be made with ICP‐MS by not discarding the supernatant of the sinter solution and by using geological reference materials for external calibration. HF digestions are slow, not universal, and may form new mineral/phases that are insoluble under high temperature conditions. The validated sample decomposition procedure combined with ICP‐MS presents an alternative to the use of HF in routine analysis of difficult to digest geological materials. 相似文献
205.
S. T. Hussain Ph.D. A. Siddiqa 《International Journal of Environmental Science and Technology》2011,8(2):351-362
Pure titanate nanotubes and titanate nanotubes doped with iron (III) and chromium (III) were fabricated by the hydrothermal treatment in methanol and sodium hydroxide mixture. The fabricated nano tubes have high surface area, high aspect ratio, consisted of very good surface morphology and high metals dispersion. The morphology, crysralline phase, composition were characterized by powdered X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Barrett-Joyner-Halenda methods and X-ray photoelectron spectroscopy. The results showed that nanotubes possess anatase phase and are composed up of 8–12 nm in diameter and 360–400 nm in length. The band gap of the titanium dioxide nanotubes was determined using transformed diffuse reflectance spectroscopy according to the Kubelka-Munk theory, showed pronounced band gap decrease on doped titanium dioxide nanotubes. The photocatalytic activity of doped nanotubes were evaluated in terms of degradation of phenol and photoreduction of carbon dioxide into methanol and ethanol under Ultra violet and Infra red irradiation. It was found that with iron (III) and chromium (III) doped titanium dioxide nanotubes exhibited much higher photocatalytic activity than undoped titanate nanotubes. 相似文献
206.
S.M. Naqvi T. Hanumanth Rao R. Natrajan K. Satyanarayana V. Divakara Rao S.M. Hussain 《Precambrian Research》1977,4(4):361-386
The Chitradurga base metal sulfide deposit is associated with eugeosynclinal metabasalts (~ 2.5 b.y.) and banded pyritiferous cherts. The pre-tectonic character of the deposit and meta-volcanics is indicated by their deformational textures, structures and radioactive age data. The mineral assemblages of these ores are similar to the Zn-Cu type of massive sulfide deposits associated with Archean—Early Precambrian eugeosynclinal metavolcanics in other shield areas. The deposit has a rather high concentration of Co; microprobe data indicate that most of it is found as cobaltite and linnaeite and that it is inhomogenously distributed in these minerals. Very strong sympathetic correlation between Co and Cu, and the simultaneous increase of both of these elements with depth has been found. The geochemistry of the Chitradurga ores and metabasalts, especially their Zn:Cu:Pb and Pb:Zn ratios, suggests that the base metal sulfide content is probably genetically related to the basaltic flows. It appears that the Chitradurga deposit belongs to the ‘massive volcanogenic’ Cu-rich class of sulfide deposits. The metal content of the ores appears to have been supplied by rapidly degassing highly undifferentiated protomantle along with the basaltic magma. 相似文献
207.
208.
Surface soil and sediment samples were collected from the surroundings of the Ittehad Chemical Industries Kalashah Kaku industrial
zone to assess residual level of 19 organochlorine pesticides (OCPs) and identify their sources. DDTs and HCHs were most prevalent
OCPs and general pattern of contamination followed the order: ∑DDT > ∑HCH > dicofol > endrin > heptachlor > dieldrin > endosulfan
II. Total measured concentrations of HCHs (6.38–121.71 ng/g) and DDTs (759.65–1811.98 ng/g) were greater in the soil samples
collected from fodder/rice fields irrigated with the factory effluents and in the surrounding of waste disposal site. Ratios
of β to γ-HCH highlighted an old mixed source of technical HCH and lindane in surface soils. Predominance of p,p′-DDT and p,p′-DDE among isomers and metabolites showed that large quantity of technical grade DDT is still present in the surrounding
surface soils. Six soil samples were categorized as heavy polluted soils (class III category of DDT > 1,000 ng/g), two soil
samples into less polluted soil between class I and II (50–500 ng/g) and 28 soil samples as non-polluted (<50 ng/g) according
to environmental quality standards for surface soils. Six soil samples were categorized as less polluted between class I and
II of HCHs (50–500 ng/g). Greater concentration of DDTs and HCHs above quality guideline poses potential exposure risk to
biological organisms, safety of agricultural products and human health in the surrounding of the Ittehad Chemical Industries. 相似文献
209.
G. D. Racca A. Marini L. Stagnaro J. van Dooren L. di Napoli B. H. Foing R. Lumb J. Volp J. Brinkmann R. Grünagel D. Estublier E. Tremolizzo M. McKay O. Camino J. Schoemaekers M. Hechler M. Khan P. Rathsman G. Andersson K. Anflo S. Berge P. Bodin A. Edfors A. Hussain J. Kugelberg N. Larsson B. Ljung L. Meijer A. Mrtsell T. Nordebck S. Persson F. Sjberg 《Planetary and Space Science》2002,50(14-15)
SMART-1 is the first of the Small Missions for Advanced Research in Technology of the ESA Horizons 2000 scientific programme. The SMART-1 mission is dedicated to testing of new technologies for future cornerstone missions, using Solar-Electric Primary Propulsion (SEPP) in Deep Space. The chosen mission planetary target is the Moon. The target orbit will be polar with the pericentre close to the South-Pole. The pericentre altitude lies between 300 and 2000 km, while the apocentre will extend to about 10,000 km. During the cruise phase, before reaching the Moon, the spacecraft thrusting profile allows extended periods for cruise science. The SMART-1 spacecraft will be launched in the spring of 2003 as an auxiliary passenger on an Ariane 5 and placed into a Geostationary Transfer Orbit (GTO). The expected launch mass is about 370 kg, including 19 kg of payload. The selected type of SEPP is a Hall-effect thruster called PPS-1350. The thruster is used to spiral out of the GTO and for all orbit maneuvers including lunar capture and descent. The trajectory has been optimised by inserting coast arcs and the presence of the Moon's gravitational field is exploited in multiple weak gravity assists.The Development Phase started in October 1999 and is expected to be concluded by a Flight Acceptance Review in January 2003. The short development time for this high technology spacecraft requires a concerted effort by industry, science institutes and ESA centres. This paper describes the mission and the project development status both from a technical and programmatic standpoint. 相似文献
210.
Nur Hussain S.M. Shahriar Ahmed Amena Muzaffar Shumi 《Singapore journal of tropical geography》2023,44(3):438-458
Urban Heat Island (UHI) refers to a phenomenon whereby urban areas experience higher temperatures compared to the surrounding areas. Remote sensing-based Land Surface Temperature (LST) measurements can be utilized to measure UHI. This study emphasized on geostatistical remote sensing-based hot spot analysis () of UHI in Dhaka, Bangladesh as a way of examining the influences of Land Use Land Cover (LULC) on UHI from 1991 to 2015. Landsat 5 and 7 satellite-based remote sensing indices were used to explore LULC, UHI and environmental footprints during the study period. The Urban Compactness Ratio (CoR) was used to calculate the urban form and augmented characteristics. The Surface Urban Heat Island (SUHI) intensity (ΔT) was also used to explore the effects of UHI on the surrounding marginal area. Based on our investigations into LULC, we discovered that around 71.34 per cent of water bodies and 71.82 percent of vegetation cover decreased from 1991 to 2015 in Dhaka city. Contrastingly, according to CoR readings, 174.13 km2 of urban areas expanded by 249.77 per cent. Our hot spot analysis also revealed that there was a 93.73 per cent increase in hot concentration zones. Furthermore, the average temperature of the study area had increased by 3.26°C. We hope that the methods and results of this study can contribute to further research on urban climate. 相似文献