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111.
In this study, organic pollutants in sandy soils are detected using a time domain relectrometry (TDR) probe system and eigendecomposition technique. As a demonstration, four types of organic fluids (motor oil, diesel oil, methanol and ethanol) were examined. Samples were prepared with different combinations of deionized water and organic fluid contents. For each experiment, reflected signals were captured by an oscilloscope, and their characteristics were identified using eigendecomposition technique. Autoregressive modeling and singular value decomposition methods were utilized for calculating the eigenvalues. The most significant eigenvalues were then identified based on their relative magnitude. Experimental results indicated that the presented system is sensitive to both water and pore fluid organic contents. For saturated conditions, signature curves were determined for identification of organic and/or water contents in soil pore fluids. 相似文献
112.
Tian C Zhang Mohamed F Dahab Germana S Nunes Cong Hu Rao Surampalli 《Water environment research》2007,79(11):2343-2351
In this study, several columns of different lengths were filled with composite soils sampled from the field at corresponding depths and then loaded intermittently with influent of a high phosphorus concentration to evaluate phosphorus fate and transport in soil. The results indicate that the height of the mass transfer zone, solvent pore velocity, and soil's life expectancy for phosphorus removal increased with depth, while the retained phosphorus per kilogram of soil and the linear adsorption equilibrium coefficient, R, decreased with depth. An equation was developed to link liquid-phase phosphorus with solvent traveling time and soil depth. The results of X-ray diffraction and washout tests indicate that calcium-phosphorus precipitation and/or crystal growth occurred in the columns. The new protocol is useful for evaluation of phosphorus fate and transport in other subsurface systems, because it allows flexible adjustments in hydraulic loadings, feed solution, and sampling schemes. 相似文献
113.
Mohamed E. I. Badawy Mostafa S. Mahmoud Marium M. Khattab 《Journal of environmental science and health. Part. B》2020,55(6):517-524
AbstractThe current study estimated the dissipation rates of abamectin, chlorfenapyr and pyridaben acaricides in pods of green beans (Phaseolus vulgaris L.) under field conditions in Egypt. Pesticides were extracted and cleaned-up by QuEChERS method and were analyzed by HPLC. The dissipation of these acaricides followed the first order kinetics model with half-life (t1/2) values 1.00, 3.50 and 1.50?days for abamectin, chlorfenapyr and pyridaben, respectively. The lowest residues, at different time intervals of field application rate of each pesticide, were observed with abamectin followed by pyridaben and then chlorfenapyr. Pre-harvest intervals (PHIs) were 10.00, 13.50 and 6.00?days for abamectin, chlorfenapyr and pyridaben, respectively and were below the established European maximum residue limits (EU MRLs) 10–14, 14–21 and 7–10?days after application, respectively. If the fresh pods will be consumed after harvest, it is expected that the presence of these pesticides in the food will have a negative impact on human health. Therefore, the elimination of the residues of these harmful pesticides must be carried out. 相似文献
114.
Waled M. El-Senousy Adel Abdel-Moneim Mahmoud Abdel-Latif Mohamed H. EL-Hefnawy Rehab G. Khalil 《Food and environmental virology》2018,10(1):89-98
This study proposed to detect the enterovirus (EV) infection in children with type 1 diabetes mellitus (T1D) and to assess the role of insufficiently treated water and sewage as sources of viral spreading. Three hundred and eighty-two serum specimens of children with T1D, one hundred serum specimens of children who did not suffer from T1D as control, and forty-eight water and sewage samples were screened for EV RNA using nested RT-PCR. The number of genome copies and infectious units of EVs in raw and treated sewage and water samples were investigated using real-time (RT)-PCR and plaque assay, respectively. T1D markers [Fasting blood glucose (FBG), HbA1c, and C-peptide], in addition to anti-Coxsackie A & B viruses (CVs A & B) IgG, were measured in control, T1D-negative EV (T1D–EV?), and T1D-positive EV (T1D–EV+) children specimens. The prevalence of EV genome was significantly higher in diabetic children (26.2%, 100 out of 382) than the control children (0%, 0 out of 100). FBG and HbA1c in T1D–EV? and T1D–EV+ children specimens were significantly higher than those in the control group, while c-peptide in T1D–EV? and T1D–EV+ children specimens was significantly lower than that in the control (n = 100; p < 0.001). Positivity of anti-CVs A & B IgG was 70.7, 6.7, and 22.9% in T1D–EV+, T1D–EV?, and control children specimens, respectively. The prevalence of EV genome in drinking water and treated sewage samples was 25 and 33.3%, respectively. The prevalence of EV infectious units in drinking water and treated sewage samples was 8.5 and 25%, respectively. Quantification assays were performed to assess the capabilities of both wastewater treatment plants (WWTPs) and water treatment plants (WTPs) to remove EV. The reduction of EV genome in Zenin WWTP ranged from 2 to 4 log10, while the reduction of EV infectious units ranged from 1 to 4 log10. The reduction of EV genome in El-Giza WTP ranged from 1 to 3 log10, while the reduction of EV infectious units ranged from 1 to 2 log10. This capability of reduction did not prevent the appearance of infectious EV in treated sewage and drinking water. Plaque purification was performed for isolation of separate EV isolates from treated and untreated water and sewage samples. Characterization of the EV amplicons by RT-PCR followed by sequencing of these isolates revealed high homology (97%) with human coxsackievirus B4 (CV B4) in 60% of the isolates, while the rest of the isolates belonged to poliovirus type 1 and type 2 vaccine strains. On the other hand, characterization of the EV amplicons by RT-PCR followed by sequencing for T1D–EV+ children specimens indicated that all samples contained CV B4 with the same sequence characterized in the environmental samples. CV B4-contaminated drinking water or treated sewage may play a role as a causative agent of T1D in children. 相似文献
115.
116.
Fouad FadhilAl-Qaim Zainab Haider Muss Ali Yuzir Jalifah Latip Mohamed Rozali Othman 《环境科学学报(英文版)》2018,30(12):134-146
Prazosin (PRZ) and levonorgestrel (LNG) are widely used as an anti-disease drugs due to their biological activity in the human body. The frequent detection of these compounds in water samples requires alternative technologies for the removal of both compounds. After electrochemical degradation of PRZ and LNG, the parent compounds could be completely removed after treatment, but the identification and characterization of by-products are necessary as well. In this study, the effects of NaCl concentration and applied voltage were investigated during the electrochemical degradation process. The results revealed that the increase of NaCl concentration and applied voltage could promote the generation of hypochlorite OCl? and then enhance the degradation of PRZ and LNG. After initial study, 6 V and 0.2 g NaCl were selected for further experiments (96% and 99% removal of PRZ and LNG after 40 min, respectively). Energy consumption was also evaluated and calculated for PRZ and LNG at 3, 6 and 8 V. Solid phase extraction (SPE) method plays an important role in enhancing the detection limit of by-products. Furthermore, characterization and identification of chlorinated and non-chlorinated by-products were conducted using an accurate liquid chromatography-time of flight/mass spectrometry LC-TOF/MS instrument. The monitoring of products during the electrochemical degradation process was performed at 6 V and 0.2 g NaCl in a 50 mL solution. The results indicated that two chlorinated products were formed during the electrochemical process. The toxicity of by-products toward E. coli bacteria was investigated at 37°C and 20 hr incubation time. 相似文献
117.
Jihene Ghedira Jamel Jebali Zied Bouraoui Mohamed Banni Lassaad Chouba Hamadi Boussetta 《环境科学学报(英文版)》2009,21(10)
The acute effects of commercial formulation of chlorpyrifos-ethyl (Dursban(r)) and the secondary treated industrial/urban effluent (STIUE) exposure on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities in hepatopancreas and gills of Mediterranean crab Carcinus maenas were investigated. After 2 d of exposure to chlorpyriphos-ethyl, the AChE activity was inhibited in both organs at concentrations of 3.12 and 7.82 μg/L, whereas the BuChE was inhibited only at higher concentration 7.82 μg/L of commercial preparation Dursban(r). The exposure of crabs to Dursban(r) (3.12 μg/L) showed a significant decrement of AChE activity at 24 and 48 h, whereas the BuChE was inhibited only after 24 h and no inhibition for both enzymes was observed after 72 h. Moreover, a significant repression of AChE activity was observed in both organs of C. maenas exposed to 5% of STIUE. Our experiments indicated that the measurement of AChE activity in gills and hepatopancreas of C. meanas would be useful biomarker of organophosphorous (OP) and of neurotoxic effects of STIUE in Tunisia. 相似文献
118.
Evans Obura Charles A. O. Midega Daniel Masiga John A. Pickett Mohamed Hassan Shinsaku Koji Zeyaur R. Khan 《Die Naturwissenschaften》2009,96(10):1169-1176
Napier grass (Pennisetum purpureum) is the most important fodder crop in smallholder dairy production systems in East Africa, characterized by small zero-grazing units. It is also an important trap crop used in the management of cereal stemborers in maize in the region. However, production of Napier grass in the region is severely constrained by Napier stunt disease. The etiology of the disease is known to be a phytoplasma, 16SrXI strain. However, the putative insect vector was yet unknown. We sampled and identified five leafhopper and three planthopper species associated with Napier grass and used them as candidates in pathogen transmission experiments. Polymerase chain reaction (PCR), based on the highly conserved 16S gene, primed by P1/P6-R16F2n/R16R2 nested primer sets was used to diagnose phytoplasma on test plants and insects, before and after transmission experiments. Healthy plants were exposed for 60 days to insects that had fed on diseased plants and acquired phytoplasma. The plants were then incubated for another 30 days. Nested PCR analyses showed that 58.3% of plants exposed to Recilia banda Kramer (Hemiptera: Cicadellidae) were positive for phytoplasma and developed characteristic stunt disease symptoms while 60% of R. banda insect samples were similarly phytoplasma positive. We compared the nucleotide sequences of the phytoplasma isolated from R. banda, Napier grass on which these insects were fed, and Napier grass infected by R. banda, and found them to be virtually identical. The results confirm that R. banda transmits Napier stunt phytoplasma in western Kenya, and may be the key vector of Napier stunt disease in this region. 相似文献
119.
Multi‐strainer model concept for conjunctive pumping of saline and non‐saline groundwater from coastal aquifers
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The current paper discusses the multi‐strainer technique developed to augment usable water by the combined use of saline and non‐saline aquifers in locations where a freshwater aquifer is underlain or overlain by a saline water aquifer. The multi‐strainer technique evaluates design criteria for the formulation of multi‐strainer schemes to supply water at an acceptable salinity limit by combined use of the saline and non‐saline aquifers. The design ratio of discharges can be maintained by adjusting the strainers’ lengths in the saline and non‐saline aquifers. The multi‐strainer scheme has been applied in the coastal aquifers of Bangladesh and found to be effective at lowering the water salinity concentrations to acceptable levels, thus increasing the availability of water for sustainable use. The multi‐strainer scheme should be designed based on the thickness of the aquifer layers to be screened, the salinity concentrations of the screened layers, and the level of salinity concentration to be maintained. 相似文献
120.
An outbreak of scurvy in Somali refugee camps* 总被引:1,自引:0,他引:1
Between June and October 1982, an outbreak of scurvy occurred in the refugee camps of Somalia. An epidemiologic investigation eventually detected more than 2,000 cases. The outbreak came at a time when the relief programme had been well established and the general health status of the refugees had otherwise stabilized. We report on 72 of the cases. Joint pain of the lower extremities and gingivitis were prominent features in the majority. Hemorrhagic phenomena were not observed and no deaths occurred. The outbreak primarily affected the poorer refugees who were unable to purchase locally available Vitamin C-containing foods. This outbreak demonstrates the vulnerability of a large population of displaced persons who are dependent on imported relief supplies for survival. 相似文献