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1.
A. Gelencsér A. Hoffer G. Kiss E. Tombácz R. Kurdi L. Bencze 《Journal of Atmospheric Chemistry》2003,45(1):25-33
Current climate models seem to underestimate the flux of solar energy absorbed by the global troposphere. All of these models are constrained with the assumption that cloud droplets consist of pure water. Here we demonstrate in a simple laboratory experiment that aromatic hydroxy-acids which are found in continental fine aerosol can react with hydroxyl radicals under typical conditions prevalent in cloud water influenced by biomass burning. The reactions yield colored organic species which do absorb solar radiation. We also suggest that the products of such reactions may be humic-like substances whose presence in continental aerosol has been confirmed but their source mechanisms are still much sought after. We also attempt to give a first order estimate of the enhancement of water absorption at a visible wavelength under atmospheric conditions. 相似文献
2.
Artificial groundwater recharge to a semi-arid basin: case study of Mujib aquifer,Jordan 总被引:1,自引:1,他引:0
Mujib watershed is an important groundwater basin which is considered a major source for drinking and irrigation water in
Jordan. Increased dependence on groundwater needs improved aquifer management with respect to understanding deeply recharge
and discharge issues, planning rates withdrawal, and facing water quality problems arising from industrial and agricultural
contamination. The efficient management of this source depends on reliable estimates of the recharge to groundwater and is
needed in order to protect Mujib basin from depletion. Artificial groundwater recharge was investigated in this study as one
of the important options to face water scarcity and to improve groundwater storage in the aquifer. A groundwater model based
on the MODFLOW program, calibrated under both steady- and unsteady-state conditions, was used to investigate different groundwater
management scenarios that aim at protecting the Mujib basin. The scenarios include variations of abstraction levels combined
with different artificial groundwater recharge quantities. The possibilities of artificial groundwater recharge from existing
and proposed dams as well as reclaimed municipal wastewater were investigated. Artificial recharge options considered in this
study are mainly through injecting water directly to the aquifer and through infiltration from reservoir. Three scenarios
were performed to predict the aquifer system response under different artificial recharge options (low, moderate, and high)
which then compared with no action (recharge) scenario. The best scenario that provides a good recovery for the groundwater
table and that can be feasible is founded to be by reducing current abstraction rates by 20% and implementing the moderate
artificial recharge rates of 26 million(M)m3/year. The model constructed in this study helps decision makers and planners in selecting optimum management schemes suitable
for such arid and semi-arid regions. 相似文献
3.
Milad Kurdi Ardeshir Hezarkhani Taymour Eslamkish 《Environmental Earth Sciences》2014,72(9):3243-3249
This paper focuses on the Qareh Sou Basin in Golestan Province, Iran. Golestan Province is the third largest cereal producer in Iran and water scarcity and salinity are major problems in this area. This study attempts to facilitate the comprehension of system behavior with respect to water quality issues and hydro-geochemical coefficients within the Qareh Sou Basin. This study was carried out during the year 2010. Various parameters, such as pH, EC, chloride, sulfate, bicarbonate, sodium, potassium, calcium and magnesium have been determined for evaluation purposes. Then, Ca/Mg, Na/Cl, Mg/(Ca + Mg), Ca/HCO3, (Ca + Mg)–(HCO3 + SO4), (Na + K)–Cl, (Ca + Mg + Na + K)–Cl, HCO3 + SO4, Ca + Mg and chloro-alkaline indices (CAI) were calculated. Results show that cation exchange probably is an important factor in the hydrochemistry and silicate mineral weathering. Also, CAI-1 plot against CAI-2 demonstrates that most of samples have positive values which suggest normal ion exchange in the system. The carbonic acid is the main agent of calcite, limestone and dolomite weathering which occurs in some stations. According to Chadha’s diagram, the type of water is determined as Ca–Mg–HCO3. 相似文献
4.
Saed Khayat Peter Möller Stefan Geyer Amer Marei Christian Siebert Fayez Abu Hilo 《Environmental Geology》2009,57(8):1739-1751
The spatial and temporal changes of the composition of the groundwater from the springs along the Wadi Qilt stream running
from the Jerusalem–Ramallah Mountains towards the Jericho Plain is studied during the hydrological year 2006/2007. The residence
time and the intensity of recharge play an important role in controlling the chemical composition of spring water which mainly
depends on distance from the main recharge area. A very important factor is the oxidation of organics derived from sewage
and garbage resulting in variable dissolved CO2 and associated HCO3
− concentration. High CO2 yields lower pH values and thus under-saturation with respect to calcite and dolomite. Low CO2 concentrations result in over-saturation. Only at the beginning and at the end of the rainy season calcite saturation is
achieved. The degradation of dissolved organic matter is a major source for increasing water hardness. Besides dissolution
of carbonates dissolved species such as nitrate, chloride, and sulfate are leached from soil and aquifer rocks together with
only small amounts of Mg. Mg not only originates from carbonates but also from Mg–Cl waters are leached from aquifer rocks.
Leaching of Mg–Cl brines is particularly high at the beginning of the winter season and lowest at its end. Two zones of recharge
are distinguishable. Zone 1 represented by Ein Fara and Ein Qilt is fed directly through the infiltration of meteoric water
and surface runoff from the mountains along the eastern mountain slopes with little groundwater residence time and high flow
rate. The second zone is near the western border of Jericho at the foothills, which is mainly fed by the under-groundwater
flow from the eastern slopes with low surface infiltration rate. This zone shows higher groundwater residence time and slower
flow rate than zone 1. Groundwater residence time and the flow rate within the aquifer systems are controlled by the geological
structure of the aquifer, the amount of active recharge to the aquifer, and the recharge mechanism. The results of this study
may be useful in increasing the efficiency of freshwater exploitation in the region. Some precautions, however, should be
taken in future plans of artificial recharge of the aquifers or surface-water harvesting in the Wadi. Because of evaporation
and associated groundwater deterioration, the runoff water should be artificially infiltrated in zones of Wadis with high
storage capacity of aquifers. Natural infiltration along the Wadis lead to evaporation losses and less quality of groundwater. 相似文献
5.
Drought analysis in Jordan under current and future climates 总被引:2,自引:0,他引:2
Mohammed I. Al-Qinna Nezar A. Hammouri Mutewekil M. Obeidat Fayez Y. Ahmad 《Climatic change》2011,106(3):421-440
Droughts have adverse socioeconomic, agricultural, and environmental impacts that can be reduced by assessing and forecasting
drought behavior. The paper presents detailed analyses of both meteorological and vegetative droughts over the period from
1970 to 2005. Standardized Precipitation Index (SPI) and Normalized Difference Vegetation Index (NDVI) have been used to quantify
drought according to severity, magnitude and spatial distribution at the Hashemite Kingdom of Jordan. Results suggest that
the country faced during the past 35 years frequent non-uniform drought periods in an irregular repetitive manner. Drought
severity, magnitudes and life span increased with time from normal to extreme levels especially at last decade reaching magnitudes
of more than 4. Generated NDVI maps spatial analyses estimate crop-area percentage damage due to severe and extremely severe
drought events occurred during October, December, and February of 2000 to be about 10%, 45%, and 30%, respectively. In response
to drought spatial extent, the paper suggest the presence of two drought types, local drought acting on one or more geographical
climatic parts and national drought, of less common but more severe, that extend over the whole country. Droughts in Jordan
act intensively during January, February and March and tend to shift position with time by alternative migrations from southern
desert parts to northern desert parts and from the eastern desert parts to highlands and Jordan Rift Valley (JRV) at the west.
The paper also investigates the potential use of Global Climate Model’s (GCM) to forecast future drought events from 2010
till 2040. Tukey HSD test indicates that ECHAM5OM GCM is capable to predicted rainfall variation at the country and suggests
future droughts to become more intensive at the northern and southern desserts with 15% rainfall reduction factor, followed
by 10% reduction at the JRV, and 5% at the highlands. 相似文献
6.
This article suggests a new approach to automatic building footprint modeling using exclusively airborne LiDAR data. The first part of the suggested approach is the filtering of the building point cloud using the bias of the Z‐coordinate histogram. This operation aims to detect the points of roof class from the building point cloud. Hence, eight rules for histogram interpretation are suggested. The second part of the suggested approach is the roof modeling algorithm. It starts by detecting the roof planes and calculating their adjacency matrix. Hence, the roof plane boundaries are classified into four categories: (1) outer boundary; (2) inner plane boundaries; (3) roof detail boundaries; and (4) boundaries related to the missing planes. Finally, the junction relationships of roof plane boundaries are analyzed for detecting the roof vertices. With regard to the resulting accuracy quantification, the average values of the correctness and the completeness indices are employed in both approaches. In the filtering algorithm, their values are respectively equal to 97.5 and 98.6%, whereas they are equal to 94.0 and 94.0% in the modeling approach. These results reflect the high efficacy of the suggested approach. 相似文献
7.
Two stratigraphic sections of the Hamam Formation (Bathonian Stage, Middle Jurassic) exposed in the western part of Wadi Zarqa region, northwestern Jordan, are described and interpreted on the basis of palynoflora and facies analysis in order to reconstruct their depositional environments and sequence stratigraphic framework, which not discussed before. Five facies associations have been identified in the Hamam Formation characterized by a mixed carbonate–siliciclastic ramp setting, ranging from incised fluvial valley fill facies, beach foreshore restricted inner ramp to high-energy shoals and mid-ramp settings. The palynoflora includes well-preserved miospore assemblages which are recorded only from the incised fluvial valley fill facies for the first time and yielded 64 miospore species belonging to 40 genera. Most of these taxa are long-ranging and have been reported from Jurassic and Cretaceous rocks worldwide, except Callialasporites dampieri, Murospora florida, Granulatisporites jurassicus, Piceites expositus, Pityosporites parvisaccatus, Leptolepidites verrucatus, and Protopinus scanicus which have short ranges in the Middle Jurassic. Furthermore, these rocks are rich in shallow-marine Neo-Tethys macro-invertebrates supporting a Bathonian age. Two third-order depositional sequences bounded by three regional unconformities at the Bajocian–Bathonian and Bathonian–Callovian stage boundaries as well as within the Bathonian are defined based upon facies characteristics and stratal geometries. A regional correlation of sequence boundaries of similar age indicates that they are eustatic in origin. 相似文献
8.
Fayez Ahmad Sherif Farouk Mohamed W. Abd El-Moghny 《Proceedings of the Geologists' Association. Geologists' Association》2014
Facies analyses and a sequence stratigraphical framework with regional correlation of the upper Campanian phosphate province are presented, based on three main sections located in Egypt (Gebel Duwi and Abu Tartur sections) and north Jordan (Umm Qais section). Fifteen facies types were grouped into: phosphate (FT1–5), carbonate (FT6–11) and siliciclastic (FT12–15) facies associations. The main component of phosphate rocks is pellets in situ and common reworked biogenic debris, especially in the upper phosphate beds (e.g. fish teeth and bones), which along with abundant Thalassinoides burrows suggests that the skeletal material was the main source for phosphates in Egypt; in contrast the common authigenic phosphatic grains (pristine) in Jordan reflect an upwelling regime. Based on age assignment as well as stratigraphical position, the phosphorite beds show great similarity that may suggests a similar origin and proximity during the period of deposition of the Duwi Formation of the Red Sea coast of Egypt and its equivalent, the Al-Hisa Phosphorite Formation in Jordan, which represents an early transgressive system tract of a depositional sequence. On the Abu Tartur plateau, the presence of sandy pyritic phosphatic grainstone (FT1) and glauconitic quartz arenite (FT12) in the middle part of the studied section, along with the absence of chert facies (FT14), reflects a more shallow marine depositional environment with increased fluvial sediment supply compared to those along the Red Sea coast and north Jordan. 相似文献
9.
We present simple analytical solutions for the unsteady advection–dispersion equations describing the pollutant concentration C(x, t) in one dimension. The solutions are obtained by using Laplace transformation technique. In this study we divided the river into two regions x ≤ 0 and x≥0 and the origin at x = 0. The variation of C(x, t) with the time t from t = 0 up to t → ∞ (the steady state case) is taken into account in our study. The special case for which the dispersion coefficient D = 0 is studied in detail. The parameters controlling the pollutant concentration along the river are determined. 相似文献
10.
Modeling of groundwater flow for Mujib aquifer, Jordan 总被引:4,自引:0,他引:4
Jordan is an arid country with very limited water resources. Groundwater is the main source for its water supply. Mujib aquifer
is located in the central part of Jordan and is a major source of drinking water for Amman, Madaba and Karak cities. High
abstraction rates from Mujib aquifer during the previous years lead to a major decline in water levels and deterioration in
groundwater quality. Therefore, proper groundwater management of Mujib aquifer is necessary; and groundwater flow modeling
is essential for proper management. For this purpose, Modflow was used to build a groundwater flow model to simulate the behavior
of the flow system under different stresses. The model was calibrated for steady state condition by matching observed and
simulated initial head counter lines. Drawdown data for the period 1985–1995 were used to calibrate the transient model by
matching simulated drawdown with the observed one. Then, the transient model was validated by using drawdown data for the
period 1996–2002. The results of the calibrated model showed that the horizontal hydraulic conductivity of the B2/A7 aquifer
ranges between 0.001 and 40m/d. Calibrated specific yield ranges from 0.0001 to 0.15. The water balance for the steady state
condition of Mujib aquifer indicated that the total annual direct recharge is 20.4 × 106m3, the total annual inflow is 13.0 × 106 m3, springs discharge is 15.3 × 106 m3, and total annual outflow is 18.7 × 106 m3. Different scenarios were considered to predict aquifer system response under different conditions. The results of the sensitivity
analysis show that the model is highly sensitive to horizontal hydraulic conductivity and anisotropy and with lower level
to the recharge rates. Also the model is sensitive to specific yield 相似文献