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Mohammad Ali Taher Nezhat Jandaghi Hamid Fazelirad Hamid Ashkenani 《Environmental monitoring and assessment》2014,186(3):1987-1997
In the present work, a batch preconcentration technique using nanoclay with 5-(4-dimethylaminobenzylidene)rhodanine coupled with electrothermal atomic absorption spectrometry was developed for the separation and determination of trace amounts of palladium. In this method, the sample solution was stirred with nanoclay as an adsorbent. Then, adsorbed palladium was subsequently eluted with HCl in acetone (1.5 mol L?1) and, finally, this eluate was injected to electrothermal atomic absorption spectrometry. Under the optimum conditions, the limit of detection and linear dynamic range were found to be 2.6 and 10.0–133 ng L?1 (in original solution), respectively. Furthermore, the enrichment factor and relative standard deviation of seven replicate determinations were 148 and ±5.1 %, respectively. This suggested method is simple, selective and sensitive and can be applied to the extraction and determination of palladium in water, tea leaves, synthetic sample and certified reference material with satisfactory results. 相似文献
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Hoda I. El-Reefy Taher Sharshar Tarek Elnimr Hussein M. Badran 《Environmental monitoring and assessment》2010,169(1-4):273-284
The sediment compartment has the ability to trap large amounts of radionuclides and to indicate the radiological impact of pollution. The present work shows the results obtained related to the concentrations of 137Cs and natural radionuclides in sediment in the Burullus Lake, Egypt. The average values of 226Ra, 232Th, and 40K in the bottom sediments collected from the east of the Burullus Lake ranged from 10.3 to 21.8 Bq/kg, from 11.9 to 34.4 Bq/kg, and from 268 to 401 Bq/kg, respectively. The study has shown that 40K concentration is nearly uniform throughout the studied area while 226Ra and 232Th are more concentrated in the northeastern shore. Lake sediments showed contamination with 137Cs (2.7–15.9 Bq/kg). The 137Cs sediment activities indicated higher concentrations in the off-shore sites. Concentrations of all γ -ray emitting radionuclides except 40K in water samples were below the detection limits. The 40K sediment–water distribution coefficients of the near-shore samples were higher than the off-shore samples. 相似文献
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Mohadeseh Madadizadeh Mohammad Ali Taher Hamid Ashkenani 《Environmental monitoring and assessment》2013,185(5):4097-4105
The present research reports on the application of modified multiwalled carbon nanotubes as a new, easily prepared, and stable solid sorbent for the column preconcentration of ultra-trace amounts of cadmium in aqueous solution. Multiwalled carbon nanotubes were oxidized with concentrated HNO3 and modified with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol and then were used as a solid phase for the column preconcentration of Cd(II). Elution was carried out with 0.5 mol?L?1 HNO3. The amount of eluted Cd(II) was measured using electrothermal atomic absorption spectrometry. Various parameters such as pH, sample and eluent flow rate, eluent concentration, breakthrough volume, and interference of a great number of anions and cations on the retention of analyte on sorbent were studied. Under the optimized conditions, the calibration graph was linear in the range of 0.67 ng?L?1 to 5.0 μg?L?1 and the detection limit (3Sb, n?=?7) was 0.14 ng?L?1 in initial solution. A preconcentration factor of 300 and relative standard deviations of ±3.6 % for seven successive determinations of 3 ng of Cd(II) were achieved. The column preconcentration was successfully applied to the analysis of river water, waste water, and Persian Gulf water sample. 相似文献
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Groundwater-level trends and implications for sustainable water use in the Kabul Basin, Afghanistan 总被引:1,自引:0,他引:1
The Kabul Basin, which includes the city of Kabul, Afghanistan, with a population of approximately 4 million, has several Afghan, United States, and international military installations that depend on groundwater resources for a potable water supply. This study examined groundwater levels in the Kabul Basin from 2004 to 2012. Groundwater levels have increased slightly in rural areas of the Kabul Basin as a result of normal precipitation after the drought of the early 2000s. However, groundwater levels have decreased in the city of Kabul due to increasing water use in an area with limited recharge. The rate of groundwater-level decrease in the city is greater for the 2008–2012 period (1.5 meters per year (m/yr) on average) than for the 2004–2008 period (0–0.7 m/yr on average). The analysis, which is corroborated by groundwater-flow modeling and a non-governmental organization decision-support model, identified groundwater-level decreases and associated implications for groundwater sustainability in the city of Kabul. Military installations in the city of Kabul (the Central Kabul subbasin) are likely to face water management challenges resulting from long-term groundwater sustainability concerns, such as the potential drying of shallow water-supply wells. Installations in the northern part of the Kabul Basin may have fewer issues with long-term water sustainability. Groundwater-level monitoring and groundwater-flow simulation can be valuable tools for assessing groundwater management options to improve the sustainability of water resources in the Kabul Basin. 相似文献