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.     

Forces dictating colloidal interactions between viruses and soil

The fate and transport of viruses in soil and aquatic environments were studied with respect to the different forces involved in the process of sorption of these viruses on soil particles. In accordance with the classical DLVO theory, we have calculated the repulsive electrostatic forces and the attractive van der Waals forces. Bacteriophages have been used as model sorbates, while different clays have been used as model sorbents. The equations used for the determination of the change in free energy for the process (deltaG) takes into consideration the roughness of the sorbent surfaces. Results indicate that attractive van der Waals forces predominate the process of sorption of the selected bacteriophages on clays.     

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.     

Effect of vermicomposting on calcium,sulphur and some heavy metal content of different biodegradable organic wastes under liming and microbial inoculation

A study was conducted to evaluate the changes in total calcium and sulphur and some heavy metal (Zn, Cu, and Pb) concentration of different organic wastes affected by liming and microorganism inoculation. Vermicomposting was an effective technology for disposal of organic substrates like municipal solid wastes (MSW), possessing comparatively higher concentration of heavy metals. The addition of lime in initial organic substrates significantly (P ≤ 0.05) increased total calcium and total sulphur content of vermicomposts. Inoculation of microorganisms significantly (P ≤ 0.05) reduced the heavy metal content of final products as compared to control. Fungal strains were comparatively more effective in detoxification of heavy metals than B. polymyxa.     

Sustainable approach for the treatment of poultry manure and starchy wastewater by integrating dark fermentation and microalgal cultivation

Journal of Material Cycles and Waste Management - Dwindling fossil fuels, and the rise in energy demand have urged us to explore alternative renewable energy forms. An integrated process of dark...     

Increasing bioavailability of phosphorus from fly ash through vermicomposting

Due to the environmental problems created by large-scale fly ash generation throughout the world, efforts are being made to recycle these materials. An important component of the recycling effort is using fly ash to improve low-fertility soils. Because availability of many nutrients is very low in fly ash, available ranges of such nutrients must be improved to increase the effectiveness of fly ash as a soil amendment. In the present study, we assessed the possibility of increasing P bioavailability in fly ash through vermicomposting in a yard experiment. Fly ash was mixed with organic matter in the form of cow (Bos taurus) dung at 1:3, 1:1, and 3:1 ratios and incubated with and without epigeic earthworm (Eisenia fetida) for 50 d. The concentration of phosphate-solubilizing bacteria (PSB) was found to increase many fold in the earthworm-treated series of fly ash and organic matter combinations compared with the series without earthworm. This helped to transform considerable amounts of insoluble P from fly ash into more soluble forms and thus resulted in increased bioavailability of the nutrients in the vermicomposted series. Among different combinations of fly ash and organic matter, P availability in fly ash due to vermicomposting was significantly higher in the 1:1 fly ash to cow dung treatment compared with the other treatments.     

Comparative study on the effect of chemicals on Alternaria blight in Indian mustard--a multi-location study in India

High severity of Altemaria blight disease is a major constraint in production of rapeseed-mustard in India. The aim of this study was to investigate the suppressive potential of chemicals viz., zinc sulphate, borax, sulphur, potash and calcium sulphate, aqueous extracts viz., Eucalyptus globosus (50 g l-1) leaf extract and garlic (Allium sativum) bulb (20 g l-1) extract, cow urine and bio-agents Trichoderma harzianum, Pseudomonas fluorescence in comparison with the recommended chemical fungicide (mancozeb), against foliar disease Alternaria blight of Indian mustard [Brassica juncea (L.) Czern. and Coss] under five different geographical locations of India. Mancozeb recorded the lowest mean severity (leaf: 33.1%; pod: 26.3%) of Alternaria blight with efficacy of garlic bulb extract alone (leaf = 34.4%; pod = 27.3%) or in combination with cow urine (leaf = 34.2%; pod = 28.6%) being statistically at par with the recommended chemical fungicide. Chemicals also proved effective in reducing Alternaria blight severity on leaves and pods of Indian mustard (leaf = 36.3-37.9%; pod = 27.5-30.1%). The effective treatments besides providing significant reduction in disease severity also enabled increase in dry seed yield of the crop (mancozeb = 2052 kg ha-1; garlic = 2006 kg ha-1; control = 1561 kg ha-1).     

Low concentration of HgCl2 drives rat hepatocytes to autophagy/apoptosis/necroptosis in a time-dependent manner

Mercury (Hg) is known to produce hepatotoxicity driving cells towards apoptosis. It was recently reported that low concentrations of Hg (5 μM) initiate autophagy in vitro within 30 min of incubation modulated by several autophagy-related gene proteins, and co-regulators through ubiquitination. The present study aimed to elucidate in vitro mode of cytotoxic responses including programed cell death in 5-μM Hg-treated rat hepatocytes. Autophagy proceeded from 30 min to 4 hr mediated by crosstalk between specific regulating factors of cell-death-signaling mechanisms. It was noted that after 4-hr incubation with 5 μM HgCl₂, cells were driven towards apoptosis followed by necroptosis within 6.5 hr. Receptor-interacting serine-threonine protein 3 (RIP3) and caspase-8 played a significant role in interlinking function. The positive role of caspase-8 with RIP3 significantly triggered caspase-3 via extrinsic apoptotic pathway. A shift from apoptosis to necroptosis occurred after 6 hr via tumor necrosis factor α-RIP3-caspase-8 pathway. No alteration in caspase-3 expression and presence of high-mobility group box 1 protein in nucleus indicated absence of apoptosis and necrosis in rat hepatocytes between 6.5 and 8 hr. Data indicated that cellular homeostasis is regulated by modulating different proteins and driving hepatocytes through autophagy to apoptosis to necroptosis in a time-dependent manner.     

Effect of mercury and methyl parathion on the ovaries of Labeo rohita (Ham)

Adult pre-spawning fish Labeo rohita were sublethally (1/5th 96h LC50) exposed to mercuric chloride and metacid-50 (methyl parathion). Accumulation of mercury and methyl parathion was studied and it was found that pre-spawning ovary appears as a potent organ for deposition of both the pollutants. RNA/DNA ratio of the control and treated fish were studied. It was found that the signifcant decrease in RNA/DNA ratio occurs after 9 and 30 days of exposure for mercury and 30 days for methyl parathion. Fluorescence microscopic studies by acridine orange staining method were also performed to show how much it is related to biochemical alterations. In some cases loss of metachromasia is correlated with the fall in RNA/DNA ratio. Some other abnormalities like fall in stage II: stage I oocyte ratio and necrosis was also observed.     

Photo-Fenton degradation of dichloromethane for gas phase treatment

A continuous photo-Fenton process has been used for the degradation of gaseous dichloromethane (DCM). By absorbing gaseous DCM into a reactive Fenton mixture, the scrubbing and degradation processes could be completed in the one reactor. Operating with a Dark Fenton solution did not result in removal of DCM any better than simply using MilliQ water. This was because the Fe(II) quickly converted to Fe(III) but was unable to regenerate. After a short time, the Fenton process was no longer operating and the DCM quickly accumulated in the reaction solution, preventing further accumulation due to a decreasing concentration gradient in the reactive solution. However, by using UV light and increasing the retention time from 20 to 50 s, there was sufficient time for the reactive solution to regenerate and continuous operation could achieve at least 65% removal of DCM from the gaseous phase at ambient temperature.