930 research outputs found
Aquifer Characterization and Quantitative Assessment of Over Exploitation of the Shallow Aquifer in AI Maqam AI Saad Area, The Eastern Region, Abu Dhabi Emirate
Al Maqam-AI Saad area is located to the west of Al Ain city on Al Ain-Abu Dhabi Highway. This area was chosen to be studied because of the rapid decline of the water levels in the shallow aquifer as a result of continuous heavy withdrawal of the Ground water. In 1990-1991, the area was recognized as one of the major ground Water depressions in the Eastern Region where more than 40 meters of draw down Were noted in the center of depression. The objective of this study is to determine the Hydraulic status of the aquifer by means of characterization and to carry out a Quantitative assessment of the shallow aquifer in the study area.The characterization of the aquifer was conducted in order to assess the hydraulic conductivity in the area by means of re-analysis of previously conducted pumping tests.
Pumping tests conducted in the area by the Ground-water Research Program (GWRP)were reanalyzed using Aquifer Test Software. The results of the reanalysis are displayed in maps of transmissivity and hydraulic conductivity. The hydraulic conductivity in the area is small and ranges from 1 to 5 meters per day with increasing trend from east to west. This range of values is consistent with the heterogeneous lithology of the Aquifer that ranges from well sorted to poorly sorted gravel interblended with clay stone, silt lone, shale, and limestone. In addition to the pumping tests analysis,geological information and ground-water salinity distribution maps were also taken into on Ideation in the aquifer characterization and hence in the aquifer assessment.
The quantitative assessment was done by means of numerical modeling. The United State Geological Survey (USGS) ground-water model MODFLOW, was used to emulate the water level decline in the area and to show that the aquifer storage is being rapidly depleted. The model was calibrated to steady-state conditions by changing aquifer hydraulic properties and boundary conditions until the simulated water levels matched predevelopment \ after levels (before 1980). A transient calibration was achieved by reasonably matching the water levels produced from the transient simulation by those observed in the years 1990 and 1995.By 1997 most of the shallow aquifer in Al Saad area (the center of the cone of Depression) became dry; in addition, a new intensive agricultural development was initiated in the south and southwest of Al Saad area. Therefore a post-audit wasPerformed to the model in order to account for the new developments. The post-audit
Was calibrated to the water levels of 2003 in which a reasonable matching was obtained Between the simulated and the actual and water levels.Predictive model simulations for 2005 and 2015 were produced under the assumption That 2003 pumping rates would continue to the year 2015. The simulations indicated that By the year 2005, some wells will dry out and by 2015 a large portion of the shallow Aquifer in the study area will be dry. The model indicated that there are many Uncertainties in the available data and more data are needed in order to produce more3ensltJ e and refined model. This model can be used as a guide for future data collection activities and management tool for the water resources in the area provided that the uncertainties are taken into consideration.The main conclusion of this study is that the large drawdown occurs due to Combination of three factors: heavy ground-water extractions, little recharge, and low Conductivity. Thus, the following recommendations can be made in order to alleviate the exploitation of aquifer: Limit the abstraction rate by prioritizing its uses, regulate ground-water use, monitor and assess ground-water conditions, enhance the replenishment of ground water by developing the ground-water recharge facilities,
and minimize contamination of fresh water aquifer
AQUIFER CHARACTERIZATION AND QUANTITATIVE ASSESSMENT OF OVER EXPLOITATION OF THE SHALLOW AQUIFER IN AL MAQAM AL SAAD AREA, THE EASTERN REGION, ABU DHABI EMIRATE
Al Maqam-AI Saad area is located to the west of Al Ain city on Al Ain-Abu Dhabi Highway. This area was chosen to be studied because of the rapid decline of the water levels in the shallow aquifer as a result of continuous heavy withdrawal of the ground water. In 1990-1991, the area was recognized as one of the major ground water depressions in the Eastern Region where more than 40 meters of draw down were noted in the center of depression. The objective of this study is to determine the hydraulic status of the aquifer by means of characterization and to carry out a quantitative assessment of the shallow aquifer in the study area. The characterization of the aquifer was conducted in order to assess the hydraulic conductivity in the area by means of re-analysis of previously conducted pumping tests. Pumping tests conducted in the area by the Ground-water Research Program (GWRP) were reanalyzed using Aquifer Test Software. The results of the reanalysis are displayed in maps of transmissivity and hydraulic conductivity. The hydraulic conductivity in the area is small and ranges from 1 to 5 meters per day wi th increasing trend from east to west. This range of va lues is consistent wi th the heterogeneous lithology of the aquifer that ranges from well sorted to poorly sorted gravel interbedded with clay 2 stone, silt lOne, shale, and limestone. In addition to the pumpmg tests analysis, geologIcal informatIon and ground-water salinity distribution maps were also taken into con IderaLIon in the aquifer characterization and hence in the aquifer assessment. The quantitatJVe as es ment was done by means of numerical modeling. The United State Geological Survey (USGS) ground-water model MODFLOW, was used to imulate th water level decline in the area and to show that the aquifer storage is being rapidly depleted. The model was calibrated to steady-state conditions by changing aquifer hydraulic properties and boundary conditions until the simulated water levels matched predevelopment \ ater levels (before 1980). A transient calibration was achieved by reasonably matching the water levels produced from the transient simulation by those observed in the years 1990 and 1995. By 1997 most of the shallow aquifer in Al Saad area (the center of the cone of depression) became dry; in addition, a new intensive agricultural development was initiated in the south and southwest of Al Saad area. Therefore a post-audit was performed to the model in order to account for the new developments. The post-audit was calibrated to the water levels of 2003 in which a reasonable matching was obtained between the simulated and the actual and water levels. Predictive model simulations for 2005 and 2015 were produced under the assumption that 2003 pumping rates would continue to the year 2015. The simulations indicated that by the year 2005 some wells will dry out and by 2015 a large portion of the shallow aquifer in the study area will be dry. The model indicated that there are many uncertainties in the available data and more data are needed in order to produce more 3 ensltJ e and refined model. This model can be used as a guide for future data collectIOn acti 1lle and a a management tool for the water resources in the area provIded that the uncertainties are taken into consideration. The main conclusion of this study is that the large drawdown
occurs due to combmatlon of three factors: hea y ground-water extractions, little recharge, and low conducti vity. Thus, the fo11o\ ing recommendations can be made in order to alleviate the exploitation of aquifer: Limit the abstraction rate by prioritizing its uses, regulate ground-water use, monitor and assess ground-water conditions, enhance the replenishment of ground water by developing the ground-water recharge facilities, and minimize contamination of fresh water aquifer
Aquifer Characterization and Quantitative Assessment of Over Exploitation of the Shallow Aquifer in AI Maqam AI Saad Area the Eastern Region, Abu Dhabi Emirate
Al Maqam-AI Saad area is located to the west of Al Ain city on Al Ain-Abu Dhabi
Highway. This area was chosen to be studied because of the rapid decline of the
water level in the shallow aquifer as a result of continuous heavy withdrawal of the
ground water. In 1990-1991, the area was recognized as one of the major ground
water depressions in the Eastern Region where more than 40 meters of draw down
were noted in the center of depression . The objective of this study is to determine the
hydraulic status of the aquifer by means of characterization and to carry out a
quantitative assessment of the shallow aquifer in the study area.
The characterization of the aquifer was conducted in order to assess the hydraulic
conductivity in the area by means of re-analysis of previously conducted pumping tests.
Pumping tests conducted in the area by the Ground-water Research Program (GWRP)
were reanalyzed using Aquifer Test Software. The results of the reanalysis are displayed
in maps of transmissivity and hydraulic conductivity. The hydraulic conductivity in the
area is small and ranges from 1 to 5 meters per day with increasing trend from east to
west. This range of values is consistent with the heterogeneous lithology of the
aquifer that ranges from well sorted to poorly sorted gravel inter bedded with clay
\u27)
stone, siltstones, shale, and limestone. In addition to the pumping tests analysis,
geological intonation and ground-water salinity distribution maps were also taken into
Consideration In the aquifer characterization and hence in the aquifer as assessmen
Heavy metals uptake by Asian swamp eel, Monopterus albus from paddy fields of Kelantan, Peninsular Malaysia: preliminary study
Swamp eel, Monopterus albus is one of the common fish in paddy fields, thus it is suitable to be a bio-monitor for heavy metals pollution studies in paddy fields. This study was conducted to assess heavy metals levels in swamp eels collected from paddy fields in Kelantan, Malaysia. The results showed zinc [Zn (86.40 µg/g dry weight)] was the highest accumulated metal in the kidney, liver, bone, gill, muscle and skin. Among the selected organs, gill had the highest concentrations of lead (Pb), cadmium (Cd) and nickel (Ni) whereas muscle showed the lowest total metal accumulation of Zn, Pb, copper (Cu), Cd and Ni. Based on the Malaysian Food Regulation, the levels of Zn and Cu in edible parts (muscle and skin) were within the safety limits. However, Cd, Pb and Ni exceeded the permissible limits. By comparing with the maximum level intake (MLI), Pb, Ni and Cd in edible parts can still be consumed. This investigation indicated that M. albus from paddy fields of Kelantan are safe for human consumption with little precaution
Copper and zinc speciation in soils from paddy cultivation areas in Kelantan, Malaysia.
The purpose of this study was to investigate the present concentration of copper (Cu) and zinc (Zn), and factors controlling the bioavailability of metals in paddy cultivation soils collected from Kelantan. Cu and Zn levels in soil samples were extracted by using the sequential extraction procedures, which are namely easily or freely, leachable and exchangeable (EFLE), acid-reducible, oxidisable-organic and resistant fractions. The highest concentration of Cu was found in the oxidisable-organic fraction (19.77±1.89 µg/g) for March, while the resistant fraction (18.29±0.87 µg/g) was the highest in April. In contrast, Zn concentration was the highest in the resistant fraction for both months. Statistically, Cu and Zn results showed a non-significant difference among these two months in the fraction of paddy soil studied. These results indicate a low bioavailability of Cu and Zn in the paddy cultivation soils. Therefore, the anthropogenic-based Cu and Zn in the paddy cultivation areas of Kelantan are expected to originate from applications of chemical fertilizers and pesticide, not from the lithogenic sources
Geofractionation of heavy metals and application of indices for pollution prediction in paddy field soil of Tumpat, Malaysia
The present study investigates the concentration of Pb, Cd, Ni, Zn, and Cu in the paddy field soils collected from Tumpat, Kelantan. Soil samples were treated with sequential extraction to distinguish the anthropogenic and lithogenic origin of Pb, Cd, Ni, Zn, and Cu. ELFE and oxidizable-organic fractions were detected as the lowest accumulation of Pb, Cd, Ni, Zn, and Cu. Therefore, all the heavy metals examined were concentrated, particularly in resistant fraction, indicating that those heavy metals occurred and accumulated in an unavailable form. The utilization of agrochemical fertilizers and pesticides might not elevate the levels of heavy metals in the paddy field soils. In comparison, the enrichment factor and geoaccumulation index for Pb, Cd, Ni, Zn, and Cu suggest that these heavy metals have the potential to cause environmental risk, although they present abundance in resistant fraction. Therefore, a complete study should be conducted based on the paddy cycle, which in turn could provide a clear picture of heavy metals distribution in the paddy field soils
Health risk from Cu and Zn contamination through consumption of paddy eel, Monopterus albus
The main objective in this study is to determine Cu and Zn concentration in edible tissues (skin and muscle) of paddy eels, Monopterus albus. The collection of M. albus samples was based on four paddy seasons (plowing, seedling, growing and harvesting). A total of 163 individuals of M. albus were collected. Edible tissues were dissected, digested and analyzed using an atomic absorption spectrometer (AAS) for metal concentration. Results showed bioaccumulation of Cu and Zn in skin was higher than in muscle tissues. Comparison with the Malaysian Food Regulation showed Cu and Zn concentrations in muscle and skin tissues were within the permissible limits. The estimation of chemical doses was calculated in order to evaluate the health risk of Malaysian population via the consumption of M. albus. Result showed Cu and Zn levels were low in muscle and skin tissues, thus suggesting edible tissues of M. albus are safe for consumption
Influence of Kenaf (KNF) Loading on Processing Torque and Water Absorption Properties of KNF-Filled Linear Low-Density Polyethylene/Poly (vinyl alcohol) (LLDPE/PVA) Composites
AbstractThe KNF-filled linear low-density polyethylene composites were prepared by using an internal mixer (Thermo Haake Polydrive) at 150°C and 50rpm rotor speed. The composites were mixed with different KNF loading, i.e., 10, 20, 30 and 40 phr. The effects of KNF loading on processing torque and water absorption of the composites were investigated. The results indicated that stabilization torque and water absorption were increased with increasing KNF loading. Composites with higher KNF loading demonstrate higher equilibrium water absorption
Introduction to the Workshop
Public health administrators are forced to consider efficiency as a criterion in their choice of preventive programs because of the numerous programs to choose from, restricted budgets, and declining caries experience in children. Interest in cost effectiveness in dental prevention has risen considerably since the initial conference on this issue at the University of Michigan in 1978. This article introduces the goals of the workshop, the nature of the work groups, and the data they will use.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66042/1/j.1752-7325.1989.tb02083.x.pd
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