نتایج جستجو برای: impact of vadose zone

تعداد نتایج: 21202281  

2003
Robert W. Smith Yoshiko Fujita Donna M. Cosgrove

Radionuclide and metal contaminants such as Sr are present beneath U.S. Department of Energy (DOE) lands in both the groundwater (e.g., 100-N area at Hanford, WA) and vadose zone (e.g., Idaho Nuclear Technology and Engineering Center at the Idaho National Engineering and Environmental Laboratory). In situ containment and stabilization of these contaminants is a cost-effective treatment strategy...

2016
Junyu Zhou Baojing Gu William H. Schlesinger Xiaotang Ju

Soil nitrate is important for crop growth, but it can also leach to groundwater causing nitrate contamination, a threat to human health. Here, we report a significant accumulation of soil nitrate in Chinese semi-humid croplands based upon more than 7000 samples from 141 sites collected from 1994 to 2015. In the 0-4 meters depth of soil, total nitrate accumulation reaches 453 ± 39, 749 ± 75, 119...

Journal: :Journal of contaminant hydrology 2004
Timothy J Kneafsey James R Hunt

Many non-aqueous phase liquids (NAPLs) are expected to spread at the air-water interface, particularly under non-equilibrium conditions. In the vadose zone, this spreading should increase the surface area for mass transfer and the efficiency of volatile NAPL recovery by soil vapor extraction (SVE). Observations of spreading on water wet surfaces led to a conceptual model of oil spreading vertic...

2004
Lawrence C. Davis Larry E. Erickson

Methyl tert-butyl ether (MTBE) has been the focus of much attention because it is used in large amounts and was reportedly relatively recalcitrant to bioremediation or natural attenuation. Beginning with a few papers a decade ago, evidence has been presented that, in fact, under suitable conditions it is amenable to bioremediation. Many species from widely disparate microbial genera are able to...

Ali Naderifar Gelareh Reyhani, Heydar Ali Kashkuli Narges Zohrabi,

Ground water is regarded as an important source of sweet water because it has less pollution potential and it has high reserve capacity compared with surface water. Therefore, it I necessary to prevent pollution from ground water, considering management of ground water resources in line with quantitative management of water resources. In this research the potential vulnerability of ground water...

2003
James E. Saiers John J. Lenhart

[1] Contaminant migration through the vadose zone may be influenced by the presence of mineral colloids that are mobilized during infiltration events. In this work, we report model calculations and experimental data on the role of pore water ionic strength in the transport of silica colloids through water-saturated and unsaturated porous media. The transport model solves the advection-dispersio...

پایان نامه :دانشگاه آزاد اسلامی - دانشگاه آزاد اسلامی واحد گرمسار - دانشکده علوم انسانی 1392

the purpose of this study was to investigate the effect of task repetition on accuracy of iranian efl learners ’speaking ability. in order to achieve this purpose, a null hypothesis was developed: there is no statistically significant difference between accuracy speaking ability in iranian efl learners by use of task repetition. ; of course i should mention that, beside this null hypothesis, an...

A Abdeh Kolahchi F Farokhian M Karimzadeh,

Nowadays the study of regional groundwater resources, because of draught ,their optimal exploitation,and reducing their pollution is a vital matter. A proper way to prevent the pollution of undergroundwaters is to locate vulnerable spots and to conduct an efficient exploitation of the ground. Using thepresent models is very essential to locate and study about vulnerable spots. For this study, G...

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