Role of competition in phytoplankton population for the occurrence and control of plankton bloom in the presence of environmental fluctuations

Termination of harmful algal blooms (HABs) and coexistence of phytoplankton–zooplankton populations are of great importance to human health, ecosystem, environment, tourism and fisheries. In this paper, we propose a three component model consisting of non-toxic phytoplankton (NTP), toxin producing phytoplankton (TPP) and zooplankton (Z). The growth of zooplankton species is assume to reduce due to toxic chemicals released by TPP population. We have extended the model proposed by Chattopadhyay et al. [Chattopadhyay, J., Sarkar, R.R., Pal, S., 2004. Mathematical modelling of harmful algal blooms supported by experimental findings. Ecol. Comp. 1, 225–235] by including competition terms between TPP and NTP. We observe the effect of competition factors both in the presence and absence of the environmental fluctuation. From our field as well as model analysis we observe that competition helps in the coexistence of the species, but if the effect of competition is very high on the TPP population, it results in planktonic bloom. It is shown that the coexistence equilibrium loses its stability when the competition coefficient crosses a critical value and resulting Hopf-bifurcation around the positive equilibrium depicting oscillations phenomena of the populations.     

Effect of noise exposure (85 dB ) on testicular adrenocortical steroidogenic key enzymes, acid and alkaline phosphatase activities of sex organs in mature albino rats

ＩｎｔｒｏｄｕｃｔｉｏｎＦｏｒｌａｓｔｔｗｏｄｅｃａｄｅｓ,ａｗａｖｅｏｆｔｈｅｅｘｐｅｒｉｍｅｎｔａｌｃｏｎｓｃｉｏｕｓｎｅｓｓｉｓｂｅｉｎｇｄｅｖｅｌｏｐｅｄｉｎｄｅｖｅｌｏｐｉｎｇｃｏｕｎｔｒｉｅｓｉｎｃｌｕｄｉｎｇＩｎｄｉａ.Ｍｏｄｅｒｎｔｅｃｈｎｏｌｏｇｙｈａｖｅｂｅｅｎｃｒｅａｔｅｄｅｎｖｉｒｏｎｍｅｎｔａｌｐｏｌｌｕｔａｎｔ,ｏｆｗｈｉｃｈｎｏｉｓｅｉｓｃｏｎｓｉｄｅｒｅｄａｓｔｈｅｗｏｒｓｔｅｎｅｍｙｏｆｈｕｍａｎｈｅａｌｔｈａｎｄａｃｕｒｓｅｏｆｏｕｒｓｏｃｉｅｔｙ .Ｎｏｉｓｅｉ…     

Monitoring waste metal pollution at Ganga Estuary via the East Calcutta Wetland areas

East Calcutta Wetlands, a Ramsar site, receives a huge amount of the city’s composite industrial effluent (～600 million liters per day) throughout the year. The waste-element-contaminated water flows down through a major storm water flow (SWF) canal into the wetland for nearly 40 km farther eastward and is finally discharged into Kultigong river that flows through the eastern limit of the wetland and that in turn unites with river Ganga. Elemental load in water and bottom sediment at selected sites of the SWF canal was assessed by proton-induced X-ray emission and atomic absorption spectroscopy techniques. Gradual decrease in concentration levels of elements was observed in both water and bottom sediments of SWF canal up to its site of confluence at Kultigong, indicating natural remediation processes taking place along the canal up to the confluence at Ganga estuary. Any further conversion of this wetland area should be prevented to get the benefit from this no-cost natural cleanup process in connection to pollution prevention.     

Transformation of nitrogen during vermicomposting of fly ash.

In view of environmental problems generated by large-scale production of fly ash, increasing attention is now being paid to the recycling fly ash as a source of plant nutrients in agriculture. However, the low amount of nitrogen in such materials forms a major constraint for such application. In the present study, the possibility of improving the N status in mixtures of fly ash and organic matter was investigated by adopting vermicomposting technology. Different combinations of fly ash and cow (Bos taurus) dung; namely fly ash alone, cow dung alone and fly ash + cow dung at 1:1, 1:3 and 3:1 ratios were incubated with and without epigeic earthworms (Eisenia fetida) for 50 days. The occurrence of N in different bio-available forms; namely easily mineralizable, NH4+ and NO3- tended to increase considerably in the series treated with earthworms. This behaviour was attributed primarily to increased microbiological activity in the vermicomposted samples and also to a considerable rise in the concentration of nitrogen-fixing bacteria in this series. Among the three combinations of vermicomposted fly ash and cow dung, the 1:1 mixture appeared to exhibit the highest availability of nitrogen.     

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.     

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.     

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.     

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.     

Studies on soil parameters of sediments from the River Ganga phosphorus mobilization,interactions with sediment and the phosphorus cycle

Large quantities of sediment are transported by the River Ganga (The Ganges) particularly In its deltaic region. Attempts have been made to study the physicochemical parameters of the bottom sediments of the River Ganga at various depths at Kamarhati and along the banks of the River Ganga in the lower deltaic region. The results give vital information regarding the pollution load carried by the river and the enrichment of its sediments with nutrients such as P, N and other substances such as C and S (as sulphates). The mobilization of the P, N, C and S (as sulphates) in the sediments is compared with their natural abundance. The enrichment of the river beds with P, the interaction of the sediment and the characteristics of the sediments are ascertained. Some aspects of the phosphorus cycle and its importance are also discussed. The recycling and reuse of sediments for agricultural purposes have been proposed in order to restore ecological imbalances due to nutrient loss.Mrs M. Chattopadhyay (née Ray) and D. Mukherjee are both post-doctorate ex-senior research scholars within the Department of Chemistry, Kalyani University, where Professor S.C. Lahiri was until recently head of department. Mr S.K. Bhattacharya is director of the Ganga Action Plan Sector, Calcutta Metropolitan Development Authority, Unnayan Bhavan (1st floor), Salt Lake, Calcutta 700 091, India. The information given in this paper is supplementary to that provided by certain of the same authors inThe Environmentalist 13(3), 199–210.