Kinetic and isotherm error optimization studies for adsorption of atrazine and imidacloprid on bark of Eucalyptus tereticornis L.

The aim of this study was to establish the bark of Eucalyptus tereticornis L. (EB) as a low cost bio-adsorbent for the removal of imidacloprid and atrazine from aqueous medium. The pseudo-first-order (PFO), pseudo-second-order (PSO), Elovich and intra-particle diffusion (IPD) models were used to describe the kinetic data and rate constants were evaluated. Adsorption data was analysed using ten 2-, 3- and 4-parameter models viz. Freundlich, Jovanovic, Langmuir, Temkin, Koble–Corrigan, Redlich–Peterson, Sips, Toth, Radke–Prausnitz, and Fritz-Schluender isotherms. Six error functions were used to compute the best fit single component isotherm parameters by nonlinear regression analysis. The results showed that the sorption of atrazine was better explained by PSO model, whereas the sorption of imidacloprid followed the PFO kinetic model. Isotherm model optimization analysis suggested that the Freundlich along with Koble–Corrigan, Toth and Fritz-Schluender were the best models to predict atrazine and imidacloprid adsorption onto EB. Error analysis suggested that minimization of chi-square (χ²) error function provided the best determination of optimum parameter sets for all the isotherms.     

Loss of crop yields in India due to surface ozone: an estimation based on a network of observations

Surface ozone is mainly produced by photochemical reactions involving various anthropogenic pollutants, whose emissions are increasing rapidly in India due to fast-growing anthropogenic activities. This study estimates the losses of wheat and rice crop yields using surface ozone observations from a group of 17 sites, for the first time, covering different parts of India. We used the mean ozone for 7 h during the day (M7) and accumulated ozone over a threshold of 40 ppbv (AOT40) metrics for the calculation of crop losses for the northern, eastern, western and southern regions of India. Our estimates show the highest annual loss of wheat (about 9 million ton) in the northern India, one of the most polluted regions in India, and that of rice (about 2.6 million ton) in the eastern region. The total all India annual loss of 4.0–14.2 million ton (4.2–15.0%) for wheat and 0.3–6.7 million ton (0.3–6.3%) for rice are estimated. The results show lower crop loss for rice than that of wheat mainly due to lower surface ozone levels during the cropping season after the Indian summer monsoon. These estimates based on a network of observation sites show lower losses than earlier estimates based on limited observations and much lower losses compared to global model estimates. However, these losses are slightly higher compared to a regional model estimate. Further, the results show large differences in the loss rates of both the two crops using the M7 and AOT40 metrics. This study also confirms that AOT40 cannot be fit with a linear relation over the Indian region and suggests for the need of new metrics that are based on factors suitable for this region.     

Analysis of soil characteristics of different land uses and metal bioaccumulation in wheat grown around rivers: possible human health risk assessment

The present study was conducted to determine the physico-chemical properties and heavy metal contents in soils under three land uses (agricultural, riverbank and roadside) from areas situated around rivers (Beas and Sutlej) in Punjab, India. Heavy metal contents in wheat samples (grain and fodder) growing in the area were also analyzed in order to find out potential human health risk through wheat consumption. The studied soils under the three land uses were found to be basic in nature with sandy texture, low soil organic matter and other soil nutrients. Comparatively higher amounts of soil nutrients were observed in soils under agricultural land use as compared to riverbank and roadside land uses. The amounts of heavy metals (Cr, Cu, Co and Pb) analyzed in soils were lower than the various national and international maximum permissible limits, but heavy metal contents observed in wheat fodder samples exceeded the maximum permissible limits for fodder. The soil-to-plant metal bioaccumulation factor was found to be highest for Cu (3.812 for soil–wheat grain and 1.874 for soil–wheat fodder), which showed the bioaccumulation of heavy metals from soils to crops, and the wheat straw-to-grain translocation factor was found to be highest for Co (4.375). The hazard index calculated to assess non-carcinogenic health risks was found above 1 for children, meaning that the wheat grains can pose health risks to children.     

Kinetics of degradation of carbendazim by B. subtilis strains: possibility of in situ detoxification

Food safety is a global concern due to the increased use of pesticides in agriculture. In grapes, carbendazim is one of the frequently detected fungicides. However, it is amenable to biodegradation. In this study, we aimed to assess the degradation of carbendazim by four Bacillus subtilis strains, which had earlier shown potential for biocontrol of grape diseases. In liquid medium, each of the four strains, namely, DR-39, CS-126, TL-171, and TS-204, could utilize carbendazim as the sole carbon source. The half-life was minimized from 8.4 days in the uninoculated spiked control to 4.0–6.2 days by the four strains. In Thompson Seedless sprayed with carbendazim at 1.0 g L^?1, the residue on grape berries in control was 0.44 mg kg^?1 after 25 days of application, whereas in grapes treated with the four B. subtilis strains, the residues had decreased to 0.02 mg kg^?1. The degradation kinetics showed low half-lives of 3.1 to 5.2 days in treated grapes as compared to 8.8 days in control. In inoculated soils, the half-lives were 5.9 to 7.6 days in autoclaved and 6.5 to 7.2 days in nonautoclaved soils as compared to 8.2 and 8.0 days in respective controls. The growth dynamics of these strains in all the three matrices was not affected by presence of carbendazim. Bacillus strains TS-204 and TL-171 showed higher degradation rate than the other two strains in all the three matrices and show promise for in situ biodegradation of carbendazim.     

A framework for assessing vulnerability of inland fisheries to impacts of climate variability in India

In recent years climate variability has threatened the sustainability of inland fisheries and dependent fishers in India. Systematic methodology to assess the vulnerability of the fisheries sector to climate variability is currently not available. Towards this end, the present work deals with the assessment of inland fisheries vulnerability to climate variations in 13 districts of West Bengal state in India. For this purpose, a composite vulnerability index (0.0–1.0) has been developed on the basis of functional relationships amongst sensitivity, exposure and adaptive capacity using 19 indicators related to inland fisheries. The data obtained reflected different spatial combinations of climate exposure, sensitivity and adaptive capacity among the districts. Five districts were highly vulnerable which was attributable to low adaptive capacity of the fishers which played an important role in altering the spatial pattern of vulnerability among the districts. Thus our research will provided an important basis for policy makers to develop appropriate adaptation strategies to minimize the risk of fisheries sector to climate variability.     

Contribution of individual components of a job cycle on overall severity of whole-body vibration exposure: a study in Indian mines

Drivers of earth-moving machines are exposed to whole-body vibration (WBV). In mining operations there can be a combination of relatively high magnitudes of vibration and long exposure times. Effective risk mitigation requires understanding of the main aspects of a task that pose a hazard to health. There are very few published studies of WBV exposure from India. This paper reports on a study that considered the contribution of the component phases of dumper operations, on the overall vibration exposure of the drivers. It shows that vibration magnitudes are relatively high, and that haulage tasks are the main contributor to the exposure. It is recommended that driver speed, haul road surfaces and vehicle maintenance/selection are optimized to ensure minimization of vibration. If this is not sufficient, operation times might need to be reduced in order to ensure that the health guidance caution zone from Standard No. ISO 2631-1:1997 is not exceeded.     

Ecotoxicological risk assessment of pentachlorophenol,an emerging DBP to plants: evaluation of oxidative stress and antioxidant responses

Environmental Science and Pollution Research - Chlorophenols are not only noticed in an effluvium of industries but also can emerge from the water treatment plants for domestic supply which poses a...     

Evaluation of RothC model using four Long Term Fertilizer Experiments in black soils, India

Carbon content in soils changes depending on the land use system, type of management practice and time. There is an increasing concern about the soil quality vis-à-vis organic carbon content in soils due to global warming and enhanced CO₂ concentration in the atmosphere. This has led to estimate carbon stock in soils at global and regional levels. The objective of the present study was to evaluate RothC model to estimate total organic carbon (TOC) changes under four long term fertilizer experimental sites representing sub-humid moist (Sarol and Nabibagh), sub-humid dry (Panjri) and semi-arid (Teligi) climate in India. The plant carbon input rate was calibrated using organic carbon and other soil parameters using RothC. The results showed that RothC could simulate changes in TOC in two contrasting eco-sites for surface soil layers. The root mean square error (RMSE) considered as modelling error ranged from 11.50 to 15.01, 4.70 to 11.60, 2.14 to 6.52 and 1.45 to 13.74 in the surface layers of Sarol, Nabibagh, Panjri, and Teligi sites, respectively. The simulation biases expressed by M (relative error) by Student‘t’ value for all the treatments at these sites were non-significant with two exceptions. Observed trends in TOC consist of an increase for all the four treatments in the sub-humid site of Sarol and Nabibagh; while manures alone or in combination increase TOC appreciably in Teligi and Panjri. TOC remained, however, almost similar over years for the control (no fertilizer or manure) and NPK treatments in all the four sites. Analysis of RothC output data showed that this model could be used as a tool to arrive at different threshold values of rainfall to influence decomposition rate modifier and thus to find out rate of organic carbon sequestration in various bioclimatic systems.     

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.