An evaluation of the dissimilarity in heat and momentum transport through quadrant analysis for an unstable atmospheric surface layer flow

Environmental Fluid Mechanics - To elucidate the role of each fluid motion in the transport of momentum and heat fluxes in an unstable atmospheric surface layer (ASL) flow from single point...     

Biosorption kinetics of heavy metals by leaf biomass of Jatropha curcas in single and multi-metal system

Biosorption of Cu²⁺, Zn²⁺, and Cr⁶⁺ from aqueous solutions by leaf biomass of Jatropha curcas was investigated as a function of biomass concentration, initial metal ion concentration, contact time, and pH of the solution systematically. The aim of this study was to optimize biosorption process and find out a suitable kinetic model for the metal removal in single and multi-metal system. The experimental data were analyzed using two sorption kinetic models, viz., pseudo-first- and pseudo-second-order equations, to determine the best fit equation for the biosorption of metal ions Cu²⁺, Zn²⁺, and Cr⁶⁺ onto the leaf biomass of J. curcas in different metal systems. The experimental data fitted well the pseudo-second-order equation and provided the best correlation for the biosorption process. The findings of the present investigation revealed that J. curcas leaf biomass was an eco-friendly and cost-effective biosorbent for the removal of heavy metal ions from wastewater.     

Metal speciation studies in the aquifer sediments of Semria Ojhapatti,Bhojpur District,Bihar

The pollution of aquifer sediments by heavy metals has assumed serious concern due to their toxicity and accumulative behavior. Changes in environmental conditions can strongly influence the behavior of both essential and toxic elements by altering the forms in which they occur and therefore quantification of the different forms of metal is more meaningful than total metal concentrations. In this study, fractionation of metal ions in aquifer sediments of Semria Ojhapatti area, Bhojpur district, Bihar has been studied to determine the ecotoxic potential of metal ions. The investigations suggest that iron, copper, and arsenic have a tendency to remain associated in the following order residual > reducible > acid-soluble > oxidizable; manganese and zinc have tendency to be associated as residual > acid-soluble > reducible > oxidizable. The risk assessment code reveals that manganese and zinc occur in significant concentration in acid-soluble fraction and therefore comes under the high risk category and can easily enter the food chain. Most of the iron, copper, and arsenic occur as immobile fraction (i.e. residual) followed by its presence in reducible fraction and would pose threat to the water quality due to changing redox conditions. The metal enrichment factor in the study area shows moderate to significant metal enrichment in the aquifer sediments which may pose a real threat in near future. The geo-accumulation index of metals also shows that the metals lie in the range of strongly contaminated (for iron at shallow depths) to moderately contaminated to uncontaminated values.     

Bactericidal effects of adsorbent on Escherichia coli for use in disinfection of drinking water

A synergistic action of silver (Ag) and groundnut husk carbon was shown, which markedly enhanced inactivation of Escherichia coli. The purpose of this study was to assess the feasibility of using a silver-impregnated groundnut husk carbon adsorbent (AdSG) for drinking water disinfection and evaluate % disinfection of E. coli. The results showed that contact of bacterial cells with AdSG resulted in a transfer of Ag ion to the cell, as evidenced by bactericidal activity. It is also possible that Ag produced generation of reactive oxygen species in the cell that led to bactericidal activity of the adsorbent. Data indicated that AdSG was effective as a bactericidal agent and may prove to be economically beneficial in drinking water disinfection.     

Unravelling the turbulent structures of temperature variations during a gust front event: a case study

Environmental Fluid Mechanics - The simultaneous observations from a Doppler weather radar and an instrumented micrometeorological tower, offer an opportunity to dissect the effects of a gust front...     

Sex ratio manipulation and decreased growth of male offspring of undernourished golden hamsters (Mesocricetus auratus)

Summary The theory that female mammals in poor condition may increase individual fitness by skewing the sex ratio of their offspring toward daughters and by investing more resources in daughters than in sons was tested in hamsters. Newly mated experimental females were food-restricted during pregnancy and lactation (RR) or during lactation only (AR). Controls received food ad libitum. Maternal body weights were assessed daily from mating to 25 days postpartum. Litter survival (% litters with at least one pup surviving on any day), litter size, offspring sex ratios (=% males), and pup weights were monitored daily from birth (Day 1) to Day 25. All control and AR dams gave birth 16 days after mating. Gestation was extended by 1–3 days for 35.4% of RR dams. RR dams weighed significantly less at parturition than controls and AR females. During lactation, AR females showed the greatest weight loss and control females the least. AR weight loss exceeded that of RR females, possibly because the former maintained larger litters. Survival was highest for controls, intermediate for AR, and lowest for RR litters. Mean sex ratio at birth was significantly less for RR (40.7%) than for control (49.6%) and AR (48.8%) litters. RR sex ratio did not change significantly postnatally. Sex ratios of control and AR litters never differed statistically from 50%. Control male pups were significantly heavier than their sisters throughout the experiment. No significant gender differences were observed for AR pup weights after Day 2 postpartum. RR female offspring weighed more than their brothers throughout the experiment, and this difference was statistically significant immediately prior to the time that pups began to feed independently (Days 14–17). RR female pup weights were similar to, and sometimes significantly greater than, weights of control daughters during the period of postnatal maternal investment. Control males were always heavier than males from the other treatments. Patterns of weight gain by AR and RR males varied with age. We conclude that underfed female hamsters are able to adjust the sex ratio of offspring prenatally and parental investment postnatally to favor daughters.     

Phytostabilisation—A Sustainable Remediation Technique for Zinc in Soils

Two studies were conducted to determine a feasible and practical phytoremediation strategy for Zn-contaminated soils. The aim of the first study was to identify promising plant species capable of Zn remediation for the soils and climatic conditions of British Columbia. The purpose of the second study was to assess the effects of soil amendments in modifying the soil properties and providing the right conditions for the plants to immobilise Zn. Promising plants for phytostabilisation in the first study (Lolium perenne, Festuca rubra and Poa pratensis) were tested in the presence of soil amendments (lime, phosphate and compost, both individually and in combination) in the second study. The efficiency of treatments to stabilise Zn was based on Zn fractionation in the soil and on absorption and partitioning of Zn in plants. Maximum Zn immobilisation was achieved in the soil by a combination of lime, phosphate and compost, in conjunction with growth of P. pratensis.     

Biodegradation of Hexachlorocyclohexane by two species of Bacillus isolated from contaminated soil

Biodegradation of α, β, γ and δ hexachlorocyclohexane (HCH) isomers was studied in broth medium and soil microcosm by Bacillus circulans and Bacillus brevis isolated from contaminated soil. Degradation of α and γ isomers by both the bacterial isolates was higher than thermodynamically stable β and δ isomers. However, B. circulans was found more effective than B. brevis for β and δ isomers. Maximum rate of degradation was recorded at 150 mg/L followed by 100 and 50 mg/L. Soil microcosm study revealed maximum degradation of HCH isomers in the treatment containing natural soil, pesticide and bacterial inocula than the treatment having sterilised soil, pesticide and bacterial isolates. Chloride release was positively co-related with HCH degradation in broth medium as well as in soil microcosm, suggesting that B. circulans and B. brevis hold promising potential by having efficient enzyme(s) required for dechlorination of HCH from contaminated sites.