No abstract

Three meter field‐aligned irregularities (3 m FAIs) associated with medium‐scale traveling ionospheric disturbances (MSTIDs) that occurred on 5 February 2008 were observed by using the Chung‐Li 52 MHz coherent scatter radar. Interferometry measurements show that the plasma structures responsible for the 3 m FAI echoes are in a clumpy shape with a horizontal dimension of about 10–78 km in a height range of 220–300 km. In order to investigate the dynamic behaviors of the plasma irregularities at different scales in the bottomside of F region, the VHF radar echo structures from the 3 m FAIs combined with the 630 nm airglow images provided by the Yonaguni all‐sky imager are compared and analyzed. The results show that the radar echoes were located at the west edge of the depletion zones of the 630 nm airglow image of the MSTIDs. The bulk echo structures of the 3 m FAIs drifted eastward at a mean trace velocity of about 30 m/s that is in general agreement with the zonal trace velocity of the MSTIDs shown in the 630 nm airglow images. These results suggest that the observed F region 3 m FAIs for the present case can be regarded as the targets that are frozen in the local region of the MSTIDs. In addition, the radar‐observed 3 m FAI echo intensity and spectral width bear high correlations to the percentage variations of the 630 nm emission intensity. These results seem to suggest that through the nonlinear turbulence cascade process, the MSTID‐associated 3 m FAIs are very likely generated from the kilometer‐scale plasma irregularities with large amplitude excited by the gradient drift instability.

In this study, sodium montmorillonite was functionalized with SH, S and Si functional groups using four different soil modifiers, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane [BAT], 3,3 0tetrathiobis(propyl-triethoxysilane) [TP], thiodiglycol bis(3-aminocrotonate) [TDBA] and (3mercaptopropyl)trimethoxysilane [MPTMS], for the effective uptake of both organic and inorganic pollutants. The uptake of inorganic (Cu 2+ , Zn 2+ ) and organic [benzene, toluene, ethylbenzene and pxylene (BTEX)] pollutants was studied with individual as well as binary mixtures. Based on the experimental results, the soil modifier MPTMS best improved the sorption characteristics and, among two metal ions, Cu 2+ showed enhanced adsorption. Sorption of BTEX was not correlated with a single parameter and hence it differed for the different cases based on the organic matter content. The obtained log K OC and log K OM values of BTEX in this study for modified montmorillonite arecomparatively larger than those of unmodified montmorillonite or natural soil. Sorption carried out in the binary mixtures showed that there is no interaction between these pollutants and the presence of one did not retard the adsorption of another. The uptake phenomenon was influenced by various combined factors such as the nature, surface charge and surface area of the modified soils.