نتایج جستجو برای: soil attenuation

تعداد نتایج: 229138  

Journal: :Journal of environmental quality 2012
Wendan Xiao Yibin Zhang Tingqiang Li Bao Chen Huan Wang Zhenli He Xiaoe Yang

The toxicity of chromium (Cr) to biota is related to its chemical forms and consequently to the redox conditions of soils. Hexavalent Cr[Cr(VI)] may undergo natural attenuation through reduction processes. In this study, the reduction kinetics of Cr(VI) in seven soils and its relationships with soil properties were investigated with laboratory incubation experiments. The results indicate that t...

Journal: :Quarterly Journal of Engineering Geology and Hydrogeology 2017

Journal: :iranian journal of nuclear medicine 2003
abbas takavar mohammad eftekhari davood beiki mohsen saghari n mostaghim

spect detects γ-rays from administered radiopharmaceutical within the patient body. γ-rays pass through different tissues before reaching detectors and are attenuated. attenuation can cause artifacts; therefore different methods are used to minimize attenuation effects. in our study efficacy of chang method was evaluated for attenuation purpose, using a custom made heart phantom. due to differe...

Journal: :Land 2023

Molar diffusion mechanism is generally considered to be the main physical process of gas transport at soil–atmosphere interface. However, advection in porous medium can considerably affect soil transport. Barometric pressure fluctuations caused by pumps one factors that affects mechanism. Most existing studies are overly focused on construction complex mathematical models and cannot exclude oth...

2004
J. Mansell J. E. Drewes

The objective of this study was to determine the primary removal mechanisms of endocrine disruptors such as steroidal hormones present in reclaimed water, specifically 17β-estradiol, estriol, and testosterone, during groundwater recharge via soil aquifer treatment (SAT). Steroidal hormones were quantified using enzyme-linked immunosorbent assays. Bench-scale studies and laboratory-scale soil co...

2016
Tao Han Zhipeng Zhao Mark Bartlam Yingying Wang

Remediation of soils contaminated with petroleum is a challenging task. Four different bioremediation strategies, including natural attenuation, biochar amendment, phytoremediation with ryegrass, and a combination of biochar and ryegrass, were investigated with greenhouse pot experiments over a 90-day period. The results showed that planting ryegrass in soil can significantly improve the remova...

2007
Claudio A. Spadotto Marcus B. Matallo Marco A.F. Gomes Luiz C. Luchini Antonio L. Cerdeira

Differences on response of mathematical models on herbicide leaching in the environment can occur due to the models and their limitations, mainly when using soil lysimeters. Tebuthiuron is a herbicide used in sugarcane crop and is applied in the recharge area of the Guarany aquifer in Brazil, one of the largest in the world. This study was conducted to compare the leaching potential of the herb...

2014
Xiaopeng Song Zeming Jian Guojun Zhang Mengran Liu Nan Guo Wendong Zhang

According to the demands of current pipeline detection systems, the above-ground marker (AGM) system based on sound detection principle has been a major development trend in pipeline technology. A novel MEMS acoustic vector sensor for AGM systems which has advantages of high sensitivity, high signal-to-noise ratio (SNR), and good low frequency performance has been put forward. Firstly, it is pr...

2007
John L. Rayner Ian Snape James L. Walworth Paul McA. Harvey Susan H. Ferguson

Natural attenuation of petroleum hydrocarbons in polar and subpolar soils is limited by low nutrients, low temperatures, and water availability. This study investigated three sites contaminated with diesel fuel and the use of aeration to remediate one of the sites at sub-Antarctic Macquarie Island. These sites were of differing ages and had different soil–water regimes. The most recent spill (N...

Journal: :iranian journal of nuclear medicine 2008
maryam naji seyed rasoul zakavi mohsen hajizadeh mehdi momennezhad

introduction: attenuation correction is a useful process for improving myocardial perfusion spect and is dependent on activity and distribution of attenuation coefficients in the body (attenuation map). attenuation artifacts are a common problem in myocardial perfusion spect. the aim of this study was to compare the effect of attenuation correction using different attenuation maps and different...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید