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121.
The resources sector in Australia makes a major contribution to the national economy, and underpins employment and population in the mining and mineral processing towns. For those towns, rapid growth in employment can generate particular pressures in local housing markets because of the relatively large size of the industry and the small housing stocks involved. Through a case study of Gladstone, the study provides a dynamic five-step population and housing model, to estimate short to medium term mining impacts of major resource developments. The model includes both the direct and indirect labour force generated by new resource sector developments and their flow-on effects on population increases. Sensitivity testing has allowed for different levels of resource development, employment multipliers and labour inflows. Three different approaches have then been applied to predict the housing price impacts of the expected population growth.  相似文献   
122.
The present study examines the natural radioactivity in some sedimentary rocks and their associated environmental impacts at Wadi Naseib area. Exposure rate (ER), dose rate (DR), radium equivalent activity (Ra(eq)), external hazard index (H(ex)), internal hazard index (H(in)) and radioactivity level index (I(gamma)) were calculated. Wadi Naseib area is covered with sedimentary rocks of early to late Paleozoic age. These rocks are classified into two types: mineralized and non-mineralized sediments. The radiometric investigations revealed that uranium and thorium contents reached up to 710 and 520 ppm, respectively, in the mineralized rocks. This was attributed to the presence of some secondary uranium minerals. All sediments had low values of eTh and K content. The exposure and dose rates exceeded public permissible values in the mineralized sediments. Exposure and dose rates were within the safety range for workers and the public in the non-mineralized sediments. The expected environmental impacts may be low due to the limited occurrence of U-mineralization and corresponding areas for radiation exposure. Some precautions and recommendations were suggested to avoid any possible environmental impacts from areas and/or raw materials of high intensity of natural radiation sources.  相似文献   
123.
124.
The incineration of solid waste produces large quantities of bottom and fly ash. Landfilling has been the primary mode of disposal of these waste materials. Shortage in landfill space and the high cost of treatment have, however, prompted the search for alternative uses of these waste materials. This study presents an experimental program that was conducted to determine the engineering properties of incinerator ash mixes for use as construction materials. Incinerator ash mixes were tested as received and around optimum compacted conditions. Compaction curves, shear strength, and permeability values of fly ash, bottom ash, and their various blends were investigated. Bottom ash tends to achieve maximum dry density at much lower water content than does fly ash. The mixes displayed a change in their cohesion and friction angle values when one of the two mix components was altered or as a result of the addition of water. The permeability of bottom ash is quite comparable to that of sand. The permeability of fly ash lies in the range of those values obtained for silts and clays. A 100% bottom ash compacted at the optimum water content has a lower density value and yields a higher friction angle and cohesion values than most construction fills. This would encourage the use of bottom ash as a fill or embankment material because free drainage of water will prevent the buildup of pore water pressures.  相似文献   
125.
The coastal seawater of Mediterranean of Alexandria receives large amount of discharged waters containing industrial wastes, sewage, and agricultural and domestic drainage. Fluoride and some parameters were( chemical and physical) determined. The data gave indication that the content and the amount of the discharged water largely affect the chemical composition of the coastal water. Stepwise regression analysis was highly significant and the model was very fruitful, where the observed and calculated values were mostly concordant. This may indicated that there was a relation between fluoride content in cosslal seawater and its content in the discharged water.  相似文献   
126.
Selenium and nano-selenium in plant nutrition   总被引:1,自引:0,他引:1  
Selenium (Se) is a naturally occurring metalloid element which occurs nearly in all environments. Se is considered as a finite and non-renewable resource on the Earth. The common sources of Se in earth’s crust occur in association with sulfide minerals such as metal selenide, whereas it is rarely found in elemental form (Se0). While there is no evidence of Se need for higher plants, several reports show that when Se added at low concentrations, Se exerts beneficial effects on plant growth. Se may act as quasi-essential micronutrient through altering different physiological and biochemical traits. Thus, plants vary considerably in their physiological and biochemical response to Se. This review focusses on the physiological importance of Se forms as well as different Se fertilizers for higher plants, especially plant growth, uptake, transport, and metabolism.  相似文献   
127.
This paper reports the biosynthesis of nanoscale zero-valent iron (nZVI) using the extracts of Shirazi thyme leaf (Th-nZVI) and pistachio green hulls (P-nZVI). Scanning electron microscopy verified the successful synthesis of the poorly crystalline nZVI with a spherical shape and diameter in the range of 40–70 nm. According to X-ray diffraction and Fourier transform infrared spectroscope analyses, the synthesised nZVI were composed of iron oxides nanoparticles and ployphenol obtained from Shirazi thyme leaf and pistachio green hulls extracts acting as both reducing and capping agents. The phosphorus removal efficiency of Th-nZVI and P-nZVI increased with time and reached equilibrium at about 4 and 2h, respectively. Sorption of phosphorus on both sorbents was observed to be pH-dependent with maximum phosphorus removal occurring in the pH range of 2–5. Langmuir, Freundlich, Redlich–Peterson, and Temkin models were used to describe phosphorus sorption at pH 5 and maximum sorption capacity for Th-nZVI and P-nZVI was about 40.52 and 29.33?mg?g?1, respectively. Correlation coefficient (R2) and standard errors of estimate showed that the Elovich model was better than other models at describing the kinetic data. These results suggested that the synthesised nZVI with Shirazi thyme leaf and pistachio green hulls extracts could be employed as an efficient sorbent for the remediation of phosphorus from contaminated water sources.  相似文献   
128.
Sea water and fish tissue samples were collected from nine sampling stations from the Great Bitter and El Temsah lakes in the Suez Canal and analysed for polycyclic aromatic hydrocarbon (PAH). The compositions of PAH determined in the dissolved fraction of sea water were measured in order to use them as chemical markers for identifying different sources of PAH pollution in this region. PAHs determined in fish tissues were measured for comparison with human health standards as consumption. The total mean PAHs concentrations in the sea water samples ranged from 0.28 to 39.57 μg l?1 with an overall mean of 10.78 and 12.38 μg l?1 for El Temsah and Bitter Lakes water, respectively. Total PAHs fractions recorded in muscle tissues of all different Osteicthyes fishes collected from Great Bitter lakes ranged from 5.8 to 218.5 μg g?1 with an overall mean of 57.98 μg g?1 during all seasons. However, they ranged from 68 to 623 μg g?1 with an overall mean of 87.69 μg g?1 recorded in El Temsah lake during four seasons (2003–2004). Benzo(a)pyrene was the most dominant PAHs found in the sea water samples from both lakes with an average concentration of 3.8 μ g l?1. Dibenzo(a,h)anthracene (DBA) was the most dominant PAHs recorded in fish samples. A maximum of 533 μg g?1 of DBA was recorded in Dahbana sp. collected from Bitter lakes during January 2004. However, a maximum of 68.7 μ g g?1 was recorded in Liza carinata species collected from El Temsah lake during July, 2004. The simultaneous occurrence of isomer ratios PHE/ANT<10 for all stations indicated that the major PAH input to water was from combustion of fossil fuel (pyrolytic source). The average ratios were 1.21 and 12.9 during winter (January 2004) and 4.3 and 8.63 during spring (April 2004) for all water samples of Great Bitter lakes and El Temsah lake, respectively. In addition, the present data demonstrate that PAHs from fossil fuel sources (MW<178) were the least significant source of PAHs in this region.  相似文献   
129.
Studies on genetic connectivity are essential for the design of management strategies for coral reef fisheries. In this study we used a mitochondrial DNA marker to investigate population structure of the reef-associated parrotfish, Scarus ghobban, from four countries, Kenya, Mauritius, Seychelles and Tanzania, in the western Indian Ocean. We obtained nucleotide sequences of the mitochondrial control region for 117 individuals. Measures of haplotype diversity were relatively high. Pairwise population differentiation (F ST) was low, but not always non-significant. Analysis of molecular variance (AMOVA) showed genetic differentiation between groups, when the data was partitioned into two groups consisting of samples from Mauritius and Tanzania in one group, and samples from Kenya and Seychelles in another group. Direction of gene flow was estimated using a Bayesian approach. Migration was sometimes asymmetric or directional, coinciding with the flow of major oceanic and coastal currents in the region. Mismatch distributions, based on the observed number of differences among haplotype pairs, produced a unimodal distribution, indicative of recent demographic expansion. Phylogenetic analyses revealed three clades without any geographic structure, suggesting recent migration between historically isolated lineages. We reconstructed the historical demography of S. ghobban and examined it in the context of Pleistocene climate stages and changes in relative sea level. Overall, these results showed that populations of S. ghobban are genetically diverse and have relatively high gene flow, with some genetic structuring in the western Indian Ocean.  相似文献   
130.
Abstract: A discharge rating is a relationship between stage and discharge at a specific point in a river stream or lake outlet structure. Rating curves are useful for interpolating and perhaps extrapolating flow measurements and for use directly in storage routing models. However, rating data and stations are limited. A generalized nondimensional mathematical expression that describes the rating relation of depth and discharge has been developed and tested against observations from 46 stations in West‐Central Florida. Three approaches were tested in sequence to select the best fit. The proposed model is a log‐linear equation with zero intercept and a slope that fits more than 50% of the stations were analyzed. The model is normalized by the depth and discharge values at 10% exceedance from data published by the U.S. Geological Survey. For ungauged applications, Q10 and d10 were derived from a relationship shown to be reasonably well correlated to the watershed drainage area. The average relative error for this parameter set shows that for the flow range up to the Q10 discharge, better than 30% agreement with the USGS rating data can be expected for about 50% of the stations. Further analysis is required to determine why so many stations exhibit such similar behavior and to identify the criteria or parameters governing the differences.  相似文献   
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