Removal of chrome dye from aqueous solutions by fly ash

The ability of fly ash to remove Omega Chrome Red ME (a chrome dye, mostly used in textile industries) from water has been studied. It has been found that low adsorbate concentration, small particle size of adsorbent, low temperature, and acidic pH of the medium favor the removal of chrome dye from aqueous solutions. The dynamics of adsorbate transport from bulk to the solid phase has been studied at different temperatures in light of the adsorption of dye on the outer surface as well as diffusion within the pores of fly ash. The applicability of Langmuir isotherm suggests the formation of monolayer coverage of dye molecules on the outer interface of adsorbent. The thermodynamics of chrome dye-fly ash system indicates spontaneous and exothermic nature of the process. The pronounced removal of chrome dye in the acidic range may be due to the association of dye anions with the positively charged surface of the adsorbent.     

Traditional seed management and genetic diversity in barley varieties in high-hill agro-ecosystems of Nepal

Chawali and Lekali are two common farmer’s barley varieties or landraces in Jumla, Nepal (2,240–3,000 m) with small to bold grains and wide adaptation from irrigated low lands to high hills. This study was undertaken to test whether features of the traditional seed system can significantly influence the diversity of a crop and its conservation on-farm. In Jumla (high-hill), the barley seed system is completely informal and is mainly from farmer to farmer. In the present study, the seed flows and the pattern of genetic diversity in barley were investigated to detect differences between the two varieties and test the divergence among populations of each variety These data suggested that Chawali, the more common variety, was less subject to homogenising gene flow between farms than was Lekali. A total of 128 farming households were surveyed for seed supply information and 128 populations for each landrace from two villages: Kartikswami and Talium were collected for SSR diversity analysis. Some 92 SSRs were screened in an initial sample of 20 barley populations of both landraces and 2 improved varieties (LG-51 and Soluwa). Of the 81 SSRs that consistently amplified, only 15 SSRs (19%) were polymorphic with gene diversity values ranging from 0.09 to 0.71. A medium to low diversity was detected among the landrace populations of barley varieties. Chawali populations were less polymorphic within ecological groups, and more divergent between than were Lekail populations. This result accords with Chawali having a more conservative local seed system.     

Use of wollastonite for the treatment of Cu(II) rich effluents

The adsorption technique using wollastonite has been applied for the removal of Cu(II) from aqueous solutions. The low concentration, high temperature and alkaline pH favor the removal of Cu(II). The Langmuir isotherm was used to represent the equilibrium data at different temperatures. The apparent heat of adsorption has been found to be 5.926 Cal mol^?1. The uptake of Cu(II) is diffusion controlled and the mass transfer coefficient is 3.6 × 10^?5 cm s^?1. The maximum removal of Cu(II) in alkaline medium has been explained on the basis of the uptake of hydrolyzed adsorbate species by the active surface sites of adsorbent.     

Nutrient contents of the leaves of the fodder tree Artocarpus Lakoocha Roxb

Artocarpus lakoocha Roxb. of the Moraceae family is cultivated in Nepal as a fodder tree. The crude protein, crude fibre and mineral contents of the fodder tree leaves were investigated during the lopping season from November 1980 to March 1982 at 800 m, 1200 m and 1550 m in eastern Nepal. The crude protein content varied from 122 to 131 g/kg DM and the crude fibre content, which seemed to remain generally low during the lopping season, varied from 171 to 202 g/kg DM. P, K, Mg, S, Mn, Fe, Cu, Zn and B concentrations in the leaves were found to be at levels which would meet the dietary requirements of cattle performing better than those found in Nepal.     

Modeling shallow water table evaporation in irrigated regions

Groundwater discharge through evaporation due to a shallow water table can be an important component of a regional scale water balance. Modeling this phenomenon in irrigated regions where soil moisture varies on short time scales is most accurately accomplished using variably saturated modeling codes. However, the computational demands of these models limit their application to field scale problems. The MODFLOW groundwater modeling code is applicable to regional scale problems and it has an evapotranspiration package that can be used to estimate this form of discharge, however, the use of time-invariant parameters in this module result in evaporation rates that are a function of water table depth only. This paper presents a calibration and validation of the previously developed MOD-HMS model code using lysimeter data. The model is then used to illustrate the dependence of bare soil evaporation rates on water table depth and soil moisture conditions. Finally, an approach for estimating the time varying parameters for the MODFLOW evapotranspiration package using a 1-D variably saturated MOD-HMS model is presented.     

Monocyclic Aromatic Hydrocarbons in Kathmandu During the Winter Season

Mixing ratios of seven monocyclic aromatic hydrocarbons, as well as NO₂, SO₂ and O₃, were measured by long path differential optical absorption spectroscopy (DOAS) at a suburban site in Kathmandu, Nepal, during Jan.–Feb. 2003. The results showed average benzene (3.9?±?1.8 ppbv), toluene (13.3?±?7.1 ppbv), and sum of xylene isomers (42.2?±?15.7 ppbv) mixing ratios in Kathmandu. The xylenes concentrations were higher than in the large cities that have been studied. The observed ratio of toluene to benzene (2.9?±?1.8) reflected the small fraction of vehicles with catalytic converters in the Kathamndu. Analysis of the late afternoon time series of aromatics, NO _x , and wind data indicated that road traffic was one of the main sources of aromatics in the urban air. In addition, the correlations between aromatics, SO₂, NO _x , and PM₁₀ during the night strongly suggested that fossil and biomass fuel burning made an important contribution to air pollution in the Kathmandu valley. Aromatic pollution was further strengthened by daily recurring stable meteorological conditions and the surrounding topography. The chemical reaction of aromatics with free radicals during the daytime could also be deduced. High ratios of phenol/benzene and para-cresol/toluene could not be explained by chemical processes, and suggested direct emission of phenol and para-cresol in the Kathmandu atmosphere.