Nutrient-limited toxin production and the dynamics of two phytoplankton in culture media: A mathematical model

In this paper we have proposed and analyzed a simple mathematical model consisting of four variables, viz., nutrient concentration, toxin producing phytoplankton (TPP), non-toxic phytoplankton (NTP), and toxin concentration. Limitation in the concentration of the extracellular nutrient has been incorporated as an environmental stress condition for the plankton population, and the liberation of toxic chemicals has been described by a monotonic function of extracellular nutrient. The model is analyzed and simulated to reproduce the experimental findings of Graneli and Johansson [Graneli, E., Johansson, N., 2003. Increase in the production of allelopathic Prymnesium parvum cells grown under N- or P-deficient conditions. Harmful Algae 2, 135–145]. The robustness of the numerical experiments are tested by a formal parameter sensitivity analysis. As the first theoretical model consistent with the experiment of Graneli and Johansson (2003), our results demonstrate that, when nutrient-deficient conditions are favorable for the TPP population to release toxic chemicals, the TPP species control the bloom of other phytoplankton species which are non-toxic. Consistent with the observations made by Graneli and Johansson (2003), our model overcomes the limitation of not incorporating the effect of nutrient-limited toxic production in several other models developed on plankton dynamics.     

Food selectivity and reproductive biology of small indigenous fish Indian river shad,Gudusia chapra (Hamilton, 1822) in a large tropical reservoir

Environmental Science and Pollution Research - Assessment of life history strategies of economically important small indigenous fishes (SIF) which are rich in nutritive values is essential and...     

Environmental quality in India: Application of environmental Kuznets curve and Sustainable Human Development Index

This study explores the trend of selected air pollutants, carbon dioxide (CO₂), nitrogen dioxide NO₂), sulfur dioxide (SO₂) and particulate matter 10 microns in diameter (PM₁₀) in India. Environmental Kuznets curves (EKC), which show the association of the economy and pollution, are fitted for selected Indian states to understand whether EKC in India fits well with the inverted “U” shape. We observed that CO₂ and PM₁₀ are steadily increasing in India. The states of Kerala and Punjab follow the inverted “U” shape of EKC, while Bihar, Uttar Pradesh, West Bengal, and Maharashtra may take decades to reduce pollutants. A new Sustainable Human Development Index calculated in this paper indicates a diverse picture of Indian states, especially in regard to environmental parameters. The government needs to implement stringent, state‐specific laws and regulations to assist in curbing air pollutants. The time has also come to represent the rankings of states in terms of an environmentally inclusive development index.     

Arsenic bioaccumulation in rice and edible plants and subsequent transmission through food chain in Bengal basin: a review of the perspectives for environmental health

Arsenic (As) is a metalloid that poses serious environmental threats due to its behemoth toxicity and wide abundance. The use of arsenic-contaminated groundwater for irrigation purpose in crop fields elevates arsenic concentration in surface soil and in the plants. In many arsenic-affected countries, including Bangladesh and India, rice is reported to be one of the major sources of arsenic contamination. Rice is much more efficient at accumulating arsenic into the grains than other staple cereal crops. Rice is generally grown in submerged flooded condition, where arsenic bioavailability is high in soil. As arsenic species are phytotoxic, they can also affect the overall production of rice, and can reduce the economic growth of a country. Once the foodstuffs are contaminated with arsenic, this local problem can gain further significance and may become a global problem, as many food products are exported to other countries. Large-scale use of rainwater in irrigation systems, bioremediation by arsenic-resistant organisms and hyperaccumulating plants, and the aerobic cultivation of rice are some possible ways to reduce the extent of bioaccumulation in rice. Investigation on a complete food chain is urgently needed in the arsenic-contaminated zones, which should be our priority in future researches.     

Biohythane production from organic wastes: present state of art

The economy of an industrialized country is greatly dependent on fossil fuels. However, these nonrenewable sources of energy are nearing the brink of extinction. Moreover, the reliance on these fuels has led to increased levels of pollution which have caused serious adverse impacts on the environment. Hydrogen has emerged as a promising alternative since it does not produce CO₂ during combustion and also has the highest calorific value. The biohythane process comprises of biohydrogen production followed by biomethanation. Biological H₂ production has an edge over its chemical counterpart mainly because it is environmentally benign. Maximization of gaseous energy recovery could be achieved by integrating dark fermentative hydrogen production followed by biomethanation. Intensive research work has already been carried out on the advancement of biohydrogen production processes, such as the development of suitable microbial consortium (mesophiles or thermophiles), genetically modified microorganism, improvement of the reactor designs, use of different solid matrices for the immobilization of whole cells, and development of two-stage process for higher rate of H₂ production. Scale-up studies of the dark fermentation process was successfully carried out in 20- and 800-L reactors. However, the total gaseous energy recovery for two stage process was found to be 53.6 %. From single-stage H₂ production, gaseous energy recovery was only 28 %. Thus, two-stage systems not only help in improving gaseous energy recovery but also can make biohythane (mixture of H₂ and CH₄) concept commercially feasible.     

Utilization of Arachis hypogaea hull,an agricultural waste for the production of activated carbons to remove phenol from aqueous solutions

Arachis hypogaea hulls, an agricultural waste, were used to prepare activated carbon by chemical activation with zinc chloride under four different activation atmospheres. The most important parameter in chemical activation was found to be the chemical ratio (activating agent/precursor). Carbonization temperature and time are the other two important variables, which had significant effect on the pore structure of carbon. The maximum Brunquer-Emmett-Teller (BET) surface area and micropore volume of the activated carbon was found to be 418 m²/g and 0.28 cm³/g, respectively. The activated carbon developed shows substantial capability to adsorb phenol from aqueous solutions. The kinetic data were fitted to the models of intraparticle diffusion, pseudo-second-order, and Lagergren, and followed more closely the pseudo-second-order chemisorption model. The isotherm equilibrium data were well fitted by the Langmuir and Freundlich models. Solution pH has significant effect on adsorption and the maximum uptake of phenol was reported at pH 3.5.     

Regulation of autophagy in rat hepatocytes treated in vitro with low concentration of mercury

Several proteins are implicated in the regulation of autophagy in cells under various physiological and pathological conditions. Recently it was found that in vitro initiation of autophagy in 5 μM mercuric chloride (HgCl₂) treated rat hepatocytes occurred within 30 min of incubation. The aim of this study was to monitor the autophagy–ubiquitination link to determine the regulatory mechanisms underlying autophagy at a concentration of 5 μM HgCl₂. Autophagic cell death was evidenced by the presence of LC3B positive hepatocytes throughout the incubation period of 4 hr. Autophagosome maturation occurred following 1 hr of metal treatment accompanied by an enhanced expression of several regulatory proteins such as p62, Keap1, and caspase-8, which drive the hepatocytes toward autophagy. In addition, the rate of increase in down-regulation in a p38 expression was significantly higher than that of extracellular signal-regulated kinase (ERK) at 1 hr incubation, followed by a significant decline in the p38 level at 2 and 4 hr following metal treatment. In contrast, the expression of ERK remained higher than that of p38 at 2 and 4 hr. Data indicate that intracellular activation of the major regulatory proteins such as LC3B, caspase-8, Keap1, p62, ERK, and p38 modulates autophagy through ubiquitination in rat hepatocytes exposed to low concentrations of Hg.     

Joint protected area management: a proposal for the management of Sanctuaries and National Parks in India

SUMMARY

With the aim of evaluating the biotic pressure on a protected area, Kuldiha Sanctuary in Orissa, India was taken as a case study. In the 19 villages lying within a 1 km radius of the Sanctuary, there are 9814 people with 19% literacy. Tribals constitute 73.3% of the population. Some 7507 head loaders collect firewood from the Sanctuary every day. In addition, 37 297 cattle enter the forest for grazing. Consequently alienating the people depending on the Sanctuary in the management and conservation of wild flora and fauna is not only futile but also detrimental to the socio-cultural-economic fabric of the ecosystem of the people. In this study, involvement of the local community in the protection and management of the Sanctuary and National Park is proposed and methods of implementation, funding and a legal framework are discussed.     

Performance and validation of a coupled parallel ADCIRC–SWAN model for THANE cyclone in the Bay of Bengal

An accurate prediction of near-shore sea-state is imperative during extreme events such as cyclones required in an operational centre. The mutual interaction between physical processes such as tides, waves and currents determine the physical environment for any coastal region, and hence the need of a parallelized coupled wave and hydrodynamic model. The present study is an application of various state-of-art models such as WRF, WAM, SWAN and ADCIRC used to couple and simulate a severe cyclonic storm Thane that developed in the Bay of Bengal during December 2011. The coupled model (ADCIRC–SWAN) was run in a parallel mode on a flexible unstructured mesh. Thane had its landfall on 30 December, 2011 between Cuddalore and Pondicherry where in-situ observations were available to validate model performance. Comprehensive experiment on the impact of meteorological forcing parameters with two forecasted tracks derived from WRF model, and JTWC best track on the overall performance of coupled model was assessed. Further an extensive validation experiment was performed for significant wave heights and surface currents during Thane event. The significant wave heights measured along satellite tracks by three satellites viz; ENVISAT, JASON-1 and JASON-2, as well in-situ near-shore buoy observation off Pondicherry was used for comparison with model results. In addition, qualitative validation was performed for model computed currents with HF Radar Observation off Cuddalore during Thane event. The importance of WRF atmospheric model during cyclones and its robustness in the coupled model performance is highlighted. This study signifies the importance of coupled parallel ADCIRC–SWAN model for operational needs during extreme events in the North Indian Ocean.     

CO2 emissions reduction from the power system in India

The power system in India accounts for nearly one-third of CO₂ emissions of the country as a whole. A comparison of some of the technical options to reduce CO₂ emissions is presented in this paper. A linear programming framework is used to simulate the integrated optimal operation of the three regional grids, and it is shown that such operations lead to lower fuel costs and to lower CO₂ emissions. The same framework is used to see how a rise in thermal efficiency translates into a CO₂ emissions reduction. Reduced fuel requirements also lead to reductions in other pollutants ie SO₂, NO_x and fly ash. The reductions in CO₂ emissions and other pollutants are at far lower cost in the case of integrated optimal operations as compared to reductions due to gas fuelled generation or thermal efficiency improvements. However, thermal efficiency improvements under optimal integrated operations result in much higher reductions in operating costs, coal consumption and total emissions of all pollutants.