Assessment of Environmental Water Demands (EWD) of Forests for Two Distinct Indian Ecosystems

Sustainable use of water and land resources requires that these scarce resources be appropriately allocated among various competing human activities. Worldwide, there is a realization now that sustainable river basin management should be accorded the highest priority, because it deals not only with technical, but also with ecological and socioeconomic aspects, and thus calls for a multidisciplinary and integrated approach. However, most of the policy and planning documents have either remained silent, or have made only implicit reference to the importance of environmental water demand (EWD) and its quantification. Therefore, in the light of its importance, a methodology has been evolved in this article for quantifying EWD for various forested areas in two distinctly different Indian river basins: Brahmani (humid zone) and Sabarmati (dry zone). The article analyzes and discusses EWD estimates at three different spatial levels: river basins, states, and districts within them, and finally presents a comparative analysis of all these results. Findings of the present study will be immensely useful in understanding various ecological issues connected with water resource projects and proposals in these river basins.     

Chromium toxicity in plants

Due to its wide industrial use, chromium is considered a serious environmental pollutant. Contamination of soil and water by chromium (Cr) is of recent concern. Toxicity of Cr to plants depends on its valence state: Cr(VI) is highly toxic and mobile whereas Cr(III) is less toxic. Since plants lack a specific transport system for Cr, it is taken up by carriers of essential ions such as sulfate or iron. Toxic effects of Cr on plant growth and development include alterations in the germination process as well as in the growth of roots, stems and leaves, which may affect total dry matter production and yield. Cr also causes deleterious effects on plant physiological processes such as photosynthesis, water relations and mineral nutrition. Metabolic alterations by Cr exposure have also been described in plants either by a direct effect on enzymes or other metabolites or by its ability to generate reactive oxygen species which may cause oxidative stress. The potential of plants with the capacity to accumulate or to stabilize Cr compounds for bioremediation of Cr contamination has gained interest in recent years.     

Using intra-flock association patterns to understand why birds participate in mixed-species foraging flocks in terrestrial habitats

Bird species are hypothesized to join mixed-species flocks (flocks hereon) either for direct foraging or anti-predation-related benefits. In this study, conducted in a tropical evergreen forest in the Western Ghats of India, we used intra-flock association patterns to generate a community-wide assessment of flocking benefits for different species. We assumed that individuals needed to be physically proximate to particular heterospecific individuals within flocks to obtain any direct foraging benefit (flushed prey, kleptoparasitism, copying foraging locations). Alternatively, for anti-predation benefits, physical proximity to particular heterospecifics is not required, i.e. just being in the flock vicinity can suffice. Therefore, we used choice of locations within flocks to infer whether individual species are obtaining direct foraging or anti-predation benefits. A small subset of the bird community (5/29 species), composed of all members of the sallying guild, showed non-random physical proximity to heterospecifics within flocks. All preferred associates were from non-sallying guilds, suggesting that the sallying species were likely obtaining direct foraging benefits either in the form of flushed or kleptoparasitized prey. The majority of the species (24/29) chose locations randomly with respect to heterospecifics within flocks and, thus, were likely obtaining antipredation benefits. In summary, our study indicates that direct foraging benefits are important for only a small proportion of species in flocks and that predation is likely to be the main driver of flocking for most participants. Our findings apart, our study provides methodological advances that might be useful in understanding asymmetric interactions in social groups of single and multiple species.     

Dissipation behavior of propargite--an acaricide residues in soil, apple (Malus pumila) and tea (Camellia sinensis)

Propargite, recently introduced in India, is an effective acaricide on a large number of crops most of which are consumed by human beings directly or after processing. Therefore, it has become important to check the dissipation behavior of propargite in edible raw commodities, processed products and in the environment. In the present study, dissipation of residue of this acaricide in soil, apple fruit and tea (green tea leaves, manufactured tea, infusion and spent leaves) was studied. Analysis was carried out using high performance-liquid chromatography with UV detection system. The dissipation rate was found to vary with the nature of studied crop/sample. In soil, half-life ranged from 43 to 45 days, while in plant matrices (tea and apple) it ranged 1.66-2.61 days. The percent transfer of propargite residue from manufactured tea to infusion was 23.60-40.00; however, 35.71-53.20% of the residues remained stuck to the spent leaves.     

N-doped mesoporous alumina for adsorption of carbon dioxide

N-doped mesoporous alumina has been synthesized using chitosan as the biopolymer template. The adsorbent has been thoroughly investigated for the adsorption of CO₂ from a simulated flue gas stream (15% CO₂ balanced with N₂) and compared with commercially available mesoporous alumina procured from SASOL, Germany. CO₂ adsorption was studied under different conditions of pre-treatment and adsorption temperature, inlet CO₂ concentration and in the presence of oxygen and moisture. The adsorption capacity was determined to be 29.4 mg CO₂/g of adsorbent at 55℃. This value was observed to be 4 times higher in comparison to that of commercial mesoporous alumina at a temperature of 55℃. Basicity of alumina surface coupled with the presence of nitrogen in template in synthesized sample is responsible for this enhanced CO₂ adsorption. Adsorption capacity for CO₂ was retained in the presence of oxygen; however moisture had a deteriorating effect on the adsorption capacity reducing it to nearly half the value.     

Stress in the workplace: a comparison of gender and occupations

Stressful incidents at work were examined using an open‐ended technique for three different occupations: clerical workers, university professors and sales associates. The study revealed both similarities and differences in stressors and coping techniques reported across occupations. Interpersonal conflict, work overload and time wasters were common across all occupations. Lack of control and work overload were reported as major stressors by the clerical group and interpersonal conflict as a major stressor by the academic and sales groups. Gender differences were also found. Copyright © 1999 John Wiley & Sons, Ltd.     

Biodegradation of anthracene and phenanthrene by bacteria isolated from oil-contaminated soil of Bangladesh

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants entering into the environment through natural and anthropogenic activities. Owing to their toxicity to various life forms including humans, detoxification of PAHs is crucial to reduce their effects on cells. In this study, we have isolated two bacteria capable of degrading two common PAHs, anthracene and phenanthrene, from contaminated soil samples by using selective enrichment culture supplemented with test PAHs as the sole source of carbon and energy. The isolated bacteria were identified and affiliated as Pseudomonas aeruginosa strain KD and Stenotrophomonas maltophilia strain RC based on their 16s rRNA gene sequences. The degradation of anthracene and phenanthrene was estimated indirectly by measuring the decolourisation extent of a redox indicator, 2, 6-dichlorophenolindophenol, incorporated into PAH-supplemented mineral salt media. In the case of anthracene, ≥90% decolourisation was recorded at 20 and 48 days for P. aeruginosa and S. Maltophilia, respectively. On the other hand, ≥94% decolourisation was recorded at 56 and 52 days for P. aeruginosa and S. maltophilia, respectively during the utilisation of phenanthrene.     

Cellular uptake and mutagenic potential of metal oxide nanoparticles in bacterial cells

Extensive production and consumption of nanomaterials such as ZnO and TiO₂ has increased their release and disposal into the environment. The accumulation of nanoparticles (NPs) in ecosystem is likely to pose threat to non-specific targets such as bacteria. The present study explored the effect of ZnO and TiO₂ NPs in a model bacterium, Salmonella typhimurium. The uptake of ZnO and TiO₂ bare NPs in nano range without agglomeration was observed in S. typhimurium. TEM analysis demonstrated the internalization and uniform distribution of NPs inside the cells. Flow cytometry data also demonstrates that both ZnO and TiO₂ NPs were significantly internalized in the S. typhimurium cells in a concentration dependent manner. A significant increase in uptake was observed in the S. typhimurium treated even with 8 and 80 ng mL⁻¹ of ZnO and TiO₂ NPs with S9 after 60 min, possibly the formation of micelles or protein coat facilitated entry of NPs. These NPs exhibited weak mutagenic potential in S. typhimurium strains TA98, TA1537 and Escherichia coli (WP2uvrA) of Ames test underscoring the possible carcinogenic potential similar to certain mutagenic chemicals. Our study reiterates the need for re-evaluating environmental toxicity of ZnO and TiO₂ NPs presumably considered safe in environment.     

Phytocapping: An alternative technique to reduce leachate and methane generation from municipal landfills

Avoiding percolation of water into refuse is the key function of landfill covers. ‘Phytocapping’ has been considered as an effective, economical and environment-friendly technique for landfill remediation. In this technique, trees are established on a layer of soil cap placed over the refuse. Soil cover acts as a ‘storage’ and trees act as ‘bio-pump and filters’. For effective functioning of this technique, it is critical that an ‘optimum’ depth of soil is placed over the refuse, and ‘suitable’ plant species are used as plant cover. Preliminary results of a phytocapping trial (using 21 tree species and two depths of soil layers) show that the established trees can remove more water than that received via rainfall and rainfall interception can reduce up to 20% of the rain reaching the soil in a 1.5 year old plantation. The study is also trialling an US numeric model ‘STOMP’ (Subsurface Transport over Multiple Phases), to calculate daily water balance, to identify suitable plant species and to optimise thickness of the soil cover to be used in phytocapping.