The chemical analysis of 59 water wells in Meshkinshar area, Ardabil province NW of IRAN has been evaluated to determine the
hydrogeochemical processes and ion concentration background in the region. The dominated hydrochemical types are Na–SO4, Ca–HCO3, Na–HCO3 and Na–Cl in the whole area. Based on the total hardness, the groundwater is soft. According to electrical conductivity and
sodium adsorption ratio, the most dominant classes are C1–S1, C2–S1 and C3–S1. The major ion concentrations are below the
acceptable level for drinking water. The groundwater salinity hazard is medium to high but the Na hazard is low to medium
and in regard of irrigation water the quality is low to medium. So the drainage system is necessary to avoid the increase
of toxic salt concentrations. 相似文献
A new closure and a modified detrainment for the simplified Arakawa–Schubert (SAS) cumulus parameterization scheme are proposed. In the modified convective scheme which is named as King Abdulaziz University (KAU) scheme, the closure depends on both the buoyancy force and the environment mean relative humidity. A lateral entrainment rate varying with environment relative humidity is proposed and tends to suppress convection in a dry atmosphere. The detrainment rate also varies with environment relative humidity. The KAU scheme has been tested in a single column model (SCM) and implemented in a coupled global climate model (CGCM). Increased coupling between environment and clouds in the KAU scheme results in improved sensitivity of the depth and strength of convection to environmental humidity compared to the original SAS scheme. The new scheme improves precipitation simulation with better representations of moisture and temperature especially during suppressed convection periods. The KAU scheme implemented in the Seoul National University (SNU) CGCM shows improved precipitation over the tropics. The simulated precipitation pattern over the Arabian Peninsula and Northeast African region is also improved.
This study proposes a landscape metrics-based method for model performance evaluation of land change simulation models. To quantify model performance at both landscape and class levels, a set of composition- and configuration-based metrics including number of patches, class area, landscape shape index, mean patch area and mean Euclidean nearest neighbour distance were employed. These landscape metrics provided detailed information on simulation success of a cellular automata-Markov chain (CA-Markov) model standpoint of spatial arrangement of the simulated map versus the corresponding reference layer. As a measure of model simulation success, mean relative error (MRE) of the metrics was calculated. At both landscape and class levels, the MRE values were accounted for 22.73 and 10.2%, respectively, which are further categorised into qualitative measurements of model simulation performance for simple and quick comparison of the results. Findings of the present study depict a hierarchical and multi spatial level assessment of model performance. 相似文献
GeoJournal - Landslides are natural destructive phenomena that can cause great damage to property and life loss. One of the fundamental proceedings to reduce the possible damage is identifying... 相似文献
The concentrations of n-alkanes, unresolved complex mixture (UCM), petroleum molecular markers, other tracers of cooking and burning emissions, and
natural background in atmospheric particles and roadside dust particles were measured at eight locations in the city center
and the suburbs of Kuala Lumpur, Malaysia. Atmospheric particles were collected using high-volume filtration (PM-10, GFF)
over 24 h average periods. Road dusts were swept up, dried and sieved. Both types of samples were extracted with dichloromethane/methanol
mixture (3:1 v/v) by ultrasonic agitation. The extracts were then fractionated by column chromatography and the alkanes subjected
to gas chromatography–mass spectrometry (GC–MS). Total extracts were also analyzed directly by GC–MS after silylation. The
molecular distributions of compounds as well as diagnostic geochemical ratios were determined in order to identify the sources
of the organic compounds. Samples collected from a rural area and lubricating oils were also analyzed for comparisons. Anthropogenic
and biogenic sources such as vehicular emissions, waxes of higher plants, food cooking operations, and biomass and domestic
refuse burning processes contributed to the organic matter content of atmospheric and to lesser extent, roadside dust particles. 相似文献
The Ba2+ ion adsorption isotherms on β-MnO2 were of the Langmuir type. The endothermic heat of adsorption (40 kJ mol?1) is ascribed to entropy contributions associated with the ion-exchange mechanism. The Ba2+ ion adsorption density was higher at pH 10 than that at pH 7, due to the more negative surface charge at the higher pH. Ba2+ ions were found to reverse the sign of the ζ potential of the MnO2 particles.More oleate was adsorbed by β-MnO2 in the presence of Ba2+ ions than in their absence. The oleate adsorption isotherms on Ba2+-activated MnO2 were of the Freundlich type and indicated an exothermic process. Hallimond flotation recovery of Ba2+-activated MnO2 was higher at pH 10 than at pH 7, although less oleate was adsorbed at the higher pH. At pH 7, Mn2+-activation led to higher recoveries than Ba2+-activation. It seems that the attraction between the surface and the activator plays an important rôle in determining the flotation recovery. 相似文献
Water samples for chemical analyses were collected in January 2012. A total of 72 samples of groundwater were collected from 72 boreholes in the Midyan Basin, northwestern Saudi Arabia. Samples were collected in polyethylene bottles and preserved and the used analytical techniques were in accordance with the standard methods from American public health association. Geochemical analyses of the groundwater samples from Midyan Basin reveal the concentration of fluoride (F) between 0.98 and 2.1 mg/l. Other parameters, e.g, pH, EC, TDS, HCO3, SO4, NO3, Cl, K, Na, Mg, and Ca have been found in a variable proportion. Among them, the concentration of EC, HCO3, K, Na and Mg is higher than the permissible limits. According to thermodynamical considerations, most of the analysed samples are graded under-saturated with respect to calcite and fluoride, while saturation has been observed in some samples. The under-saturation could probably be attributed to low concentration of calcite and fluoride in the studied wells. Fluoride concentration shows weak positive correlation with EC, TDS, Na, Cl, and SO4. Factors controlling the concentration of fluoride (F) in the studied samples are the area climate, water chemistry and the presence of accessory minerals in the rocks through which groundwater is circulating, besides the anthropogenic activities in the area. 相似文献
Lush Hyrcanian mixed temperate forests are globally important ecosystems with considerable ecological and economic values and high variety of ecosystem services (ES). In this study, an ES-based approach is adopted to develop a spatial conservation framework for Gorganrood Watershed, northeastern Iran. In doing so, the integrated valuation of ecosystem services and trade-offs modeling tool was implemented to spatially quantify a collection of five ES including soil retention, habitat quality (as a proxy for biodiversity), water yield, food supply and carbon storage. These services were integrated into a single layer based on the Total Ecosystem Services (TES) index. By performing correlation analyses, the type and the strength of relationships between ES, TES index values and different land features were analyzed to reveal which land-use categories at what locations are more capable to provide bundles of ES. Accordingly, Hyrcanian mixed temperate forests in the southern sub-watersheds of the area were detected to have higher potential for simultaneous provisioning of multiple ES. In addition, we show that biodiversity hotspots and provision of other ES are highly correlated and thus that conservation of one group can be beneficial for the other. Our findings are particularly applicable in areas where complex network of land-uses and limited resources are major barriers against effective conservation of Hyrcanian mixed temperate forests. 相似文献
Gold production in South Africa is projected to continue its decline in future, and prospects for discovery of new high-grade deposits are limited. Many of the mining companies have resorted to mining and processing low-grade and complex gold ores. Such ores are technically challenging to process, which results in low recovery rates, excessive reagent consumption and high operating costs when compared to free-milling gold ores. In the Witwatersrand mines, options of blending low-grade gold ores with high-grade ores exist. Although it is well known that most of the Witwatersrand gold ores are highly amenable to gold cyanidation, not much is known on the leachability of blended ores, especially the effects of mineralogical and metallurgical variability between different gold ores. In this study, we apply a geometallurgical approach to investigate mineralogical and metallurgical factors that influence the leaching of blended ores in a set of bottle shaker and reactor column tests. Three gold-bearing conglomerate units, so-called reefs, i.e., Carbon Leader Reef, Ventersdorp Contact Reef and the Black Reef, all in the Carletonville goldfield, were sampled. The ores were prepared using a terminator jaw crusher followed by vertical spindle pulverizer (20 kg aliquot) and high-pressure grinding rolls (80 kg aliquot). Mineralogical analysis was conducted using a range of complementary tools such as optical microscopy, QEMSCAN and micro–XCT. The results show that Witwatersrand gold ores are amenable to the process of ore blending. Some of the ores, however, contain impervious inert gangue and reactive ore minerals. Leach solution can only access gold locked in impervious gangue minerals through HPGR-induced pores and/or cracks. The optimum ore blending ratio of the bottle shaker experiments (p80?=???75 μm) comprises 60% Carbon Leader Reef, 20% Ventersdorp Contact Reef and 20% Black Reef and yields 92% recovered Au over a leach period of 40 h. Blended ores with high carbonaceous material (>?1 wt% carbonaceous material, (Black Reef?=?36–60%) yield lower recoveries of 60–69% Au). Ore leaching at the mixed-bed reactor column (??75 μm and ??5.6/+?4 mm) yields about 70% over a leach period of two weeks. We therefore suggest that the feasibility of ore blending is strongly controlled by the mineralogy of the constituent ores and that a mixed-bed reactor may be a viable alternative method for leaching of the low-grade Witwatersrand gold ores. Material from certain reefs, such as the Black Reef, has synergistic/antagonistic (nonadditive) blending effects. The overall implication of this study is that ore blending ratios, effects of comminution on mineral liberation, an association of gold with other minerals, and gold adsorption behavior will greatly inform future technology choices in the area of geometallurgy.
