Physiological and metabolic effect of mercury accumulation in higher plants system

Heavy metals, lead (Pb) and mercury (Hg) are non-essential elements. Plants absorb these metals from soil, water and air through their roots and leaves. Heavy metals are the major environmental pollutants, which spread to soil through the use of pesticides, herbicides and micronutrient fertilizers, industrial effluents, decay of junk materials and sewage sludge, vehicular emissions, re-suspended road dust, diesel generator sets and coal-based thermal power plants. Sewage and sludge have contributed to heavy metal contamination of peri-urban lands and vegetable crops. The present review focuses on the effects of various concentrations of Hg on growth of young and mature seedlings as well as on nitrate reductase activity and nitrate assimilation in intact and excised seedling, especially the mechanism underlying nitrate reductase regulation by this heavy metal. Evidence indicates that mercury exerts significant adverse effects on the physiological activity of plants.     

Effect of complete and skeleton photoperiods in baya weaver, Ploceus philippinus

A study was performed to investigate the effects of complete and skeleton photoperiods on gonadal stimulation in baya weaver, Ploceus philippinus. In August 2003, five groups of acclimatized birds (n = 7 each) were exposed to 6L: 13D: 1L: 4D, 6L: 6D: 1L: 11D, 11L: 13D and 13L: 11D. Birds were refractory and their exposure to 6L:13D:1L:4D, 6L:6D:1L:11D, 11L:13D and 13L:11D did not evoke any response. This clearly indicates that the birds were insensitive to the stimulatory effects of these photoperiods and perceived them as short days. An attempt was made to test the responsivity by subjecting all these groups to long day exposure after 16 weeks of experiment. Under 16L: 8D, birds did not show a response during the first 4 weeks of exposure (week 16 to week 20), but thereafter there was a significant photoinduction except 11L:13D (week 24), but the rate and magnitude was different. Until the end of the experiment (32 weeks), all groups of birds had maximum testicular volume except 11L:13D. Birds pre-exposed to 6L:13D:1L:4D, 6L:6D:1L:11D, 11L:13D and 13L:11D responded to 16L:8D, which suggests that these photoperiods helped the birds in recovering their photosensitivity. The results from this experiment indicate that baya weaver interprets a light period depending when the light falls relative to its endogenous circadian system.     

Multivariate statistical techniques for the evaluation of spatial and temporal variations in water quality of the Mahanadi river–estuarine system (India) – a case study

Spatial and temporal distributions of water quality using multivariate statistical techniques for the evaluation of nutrients (NO₂-N, NO₃-N, NH₄-N, PO₄-P, SiO₄-Si, total N, total P) in relation to some physico-chemical features (DO, BOD, TSS, TDS, SO₄²⁻, Cl⁻) were studied for 31 different stations of the Mahanadi river–estuarine system in the eastern part of India. The seasonal nutrient variations (except SiO₄-Si) exhibit higher values during monsoon season in unpolluted stations and the reverse trends for polluted stations, which are related to agricultural run-off and regional anthropogenic activities respectively. Silicate shows a well defined pattern of distribution with a higher concentration during the monsoon, which is slightly removed from the estuarine water of Mahanadi during the pre-monsoon season. The results of R-mode factor analyses revealed that anthropogenic contributions are responsible for the increase in nutrients and the decrease in DO and pH levels of the water. The magnitude of BOD with respect to total N and P demonstrates the intensity of organic pollution in the system. The removal of silicate in the saline system is clearly visible through factor analysis and the different mode of association of TSS is reflected seasonally. The relationships among the stations are highlighted by cluster analysis, represented in dendograms to categorize different levels of contamination.     

Measuring ammonia concentrations and emissions from agricultural land and liquid surfaces: a review

Aerial ammonia concentrations (Cg) are measured using acid scrubbers, filter packs, denuders, or optical methods. Using Cg and wind speed or airflow rate, ammonia emission rate or flux can be directly estimated using enclosures or micrometeorological methods. Using nitrogen (N) recovery is not recommended, mainly because the different gaseous N components cannot be separated. Although low cost and replicable, chambers modify environmental conditions and are suitable only for comparing treatments. Wind tunnels do not modify environmental conditions as much as chambers, but they may not be appropriate for determining ammonia fluxes; however, they can be used to compare emissions and test models. Larger wind tunnels that also simulate natural wind profiles may be more useful for comparing treatments than micrometeorological methods because the latter require larger plots and are, thus, difficult to replicate. For determining absolute ammonia flux, the micrometeorological methods are the most suitable because they are nonintrusive. For use with micrometeorological methods, both the passive denuders and optical methods give comparable accuracies, although the latter give real-time Cg but at a higher cost. The passive denuder is wind weighted and also costs less than forced-air Cg measurement methods, but it requires calibration. When ammonia contamination during sample preparation and handling is a concern and separating the gas-phase ammonia and aerosol ammonium is not required, the scrubber is preferred over the passive denuder. The photothermal interferometer, because of its low detection limit and robustness, may hold potential for use in agriculture, but it requires evaluation. With its simpler theoretical basis and fewer restrictions, the integrated horizontal flux (IHF) method is preferable over other micrometeorological methods, particularly for lagoons, where berms and land-lagoon boundaries modify wind flow and flux gradients. With uniform wind flow, the ZINST method requiring measurement at one predetermined height may perform comparably to the IHF method but at a lower cost.     

Charismatic leadership and follower effects

On the basis of the current theories of charismatic leadership, several possible follower effects were identified. It is hypothesized that followers of charismatic leaders could be distinguished by their greater reverence, trust, and satisfaction with their leader and by a heightened sense of collective identity, perceived group task performance, and feelings of empowerment. Using the Conger–Kanungo charismatic leadership scale and measures of the hypothesized follower effects, an empirical study was conducted on a sample of 252 managers using structural equation modelling. The results show a strong relationship between follower reverence and charismatic leadership. Follower trust and satisfaction, however, are mediated through leader reverence. Followers' sense of collective identity and perceived group task performance are affected by charismatic leadership. Feelings of empowerment are mediated through the followers' sense of collective identity and perceived group task performance. Copyright © 2000 John Wiley & Sons, Ltd.     

Thermo-mechanical Characterization of New Natural Cellulose Fiber from Zmioculus Zamiifolia

Journal of Polymers and the Environment - The environmental impact on pollution has attracted the use of natural cellulose fibers as a replacement for synthetic materials due its ecofriendly nature...     

Occupational health hazards and wide spectrum of genetic damage by the organic solvent fumes at the workplace: A critical appraisal

Environmental Science and Pollution Research - Long-term exposure to organic solvents is known to affect human health posing serious occupational hazards. Organic solvents are genotoxic, and they...     

Assessing site suitability potential for soil and water conservation structures by using modified micro-watershed prioritization method: geomorphometric and geomatic approach

Environment, Development and Sustainability - Efficiency of soil water conservation (SWC) structure depends on its precise locations as well as its success in reducing surface runoff, soil erosion...