Assessing the spatial variation of cropping intensity using multi-temporal Sentinel-2 data by rule-based classification

Environment, Development and Sustainability - The present study was conducted to analyze cropping intensity of four blocks (Mogra-Chinsurah, Polba-Dadpur, Singur and Haripal) of the Gangetic...     

Lead induced changes in antioxidant metabolism of horsegram (Macrotyloma uniflorum (Lam.) Verdc.) and bengalgram (Cicer arietinum L.)

One-month old horsegram (Macrotyloma uniflorum (Lam.) Verdc. cv VZM1) and bengalgram (Cicer arietinum L. cv Annogiri) were exposed to different regimes of lead stress as Pb(NO3)2 at 0, 200, 500 and 800 ppm concentrations. The extent of oxidative damage as the rate of lipid peroxidation, antioxidative response and the accumulation of lead in roots and shoots of both plants were evaluated after 12 days of lead stress. Lead (Pb) treated plants showed increased levels of lipid peroxidation as evidenced from the increased malondialdehyde content coupled with the increase in the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione reductase (GR), glutathione S-transferase (GST) compared to control (untreated) plants. Lead stress caused significant changes in the activity of antioxidative enzymes. The effect of lead was found to be concentration dependent. Higher concentration of lead (800 ppm) resulted 2- to 3-fold increase in SOD, catalase and peroxidase activities, 3- to 5-fold increase in GR activity and 3- to 4-fold increase in GST activity in roots and leaves of both horsegram and bengalgram plants. Lead stress caused a significant increase in the rate of peroxidation as showed in the levels of malondialdehyde content in roots and leaves of both plant species. Horsegram registered lower Pb accumulation than bengalgram, however localization of Pb was greater in roots than leaves in both plants. In general, lipid peroxide levels and antioxidative enzyme activities were higher in horsegram than bengalgram and also more in roots than leaves which best concordance with the lead contents of both the plants and organs. These results suggest that Pb toxicity causes oxidative stress in plants and the antioxidative enzymes SOD, CAT, POD, GR, GST could play a pivotal role against oxidative injury.     

Acceleration of catalase and peroxidase activities in Lemna minor L. and Allium cepa L. in response to low levels of aquatic mercury

The purpose of this study was to assess certain physiological responses of Lemna minor L. (duckweed) and Allium cepa L. (onion) to aquatic mercury at low concentrations. Following a 96-h exposure of plants to nutrient medium contaminated with known levels of mercuric chloride (HgCl(2)), 0.001 to 4 mg litre(-1) (0.0007 to 2.95 mg Hg litre(-1)) or methyl mercuric chloride (MeHgCl(2)), 0.0001 to 0.1 mg litre(-1) (0.0007 to 0.07 mg Hg litre(-1)), the physiological endpoints measured were the growth of fronds (Lemna minor) or roots (Allium cepa), and catalase and peroxidase activities in both plant assays. The EC(50) for HgCl(2) on the basis of the growth curve of Lemna minor was found to be 2.1 mg litre(-1). HgCl(2) and MeHgCl(2) were lethal to L. minor at concentrations of 4 and 0.01 mg litre(-1), respectively. The range of low concentrations that accelerated growth as well as enzymic activities in L. minor was 0.004 to 0.04 mg litre(-1) for HgCl(2) and 0.001 mg litre(-1) for MeHgCl(2). HgCl(2) and MeHgCl(2) induced maximum enzymic activity in Lemna fronds at concentrations of 0.008 and 0.0005 mg litre(-1), respectively. In Allium roots, catalase activity was accelerated at all the concentrations of HgCl(2) (0.001-2 mg litre(-1)) and MeHgCl(2) (0.0001-0.1 mg litre(-1)) tested. The activity of peroxidase was, however, accelerated by HgCl(2) at concentration range 0.01-1.0 mg litre(-1), or by MeHgCl(2) at 0.001 mg litre(-1). The concentrations of HgCl(2) and MeHgCl(2) that induced the highest enzymic activity in Allium roots were 0.05 mg litre(-1) and 0.001 mg litre(-1), respectively.     

Semi-analytical study on environmental dispersion of settling particles in a width-independent wetland flow

Environmental Fluid Mechanics - Predicting the evolution of environmental dispersion of settling particles in wetland flows has a wide range of applications in ecological engineering. In the...     

Physico-chemical and bacteriological investigation on the River Torsa of North Bengal

A few physico-chemical and bacteriological parameters on certain locations of the river Torsa was studied. The major characteristics of Torsa river water were high alkalinity, high concentration of free ammonia with respect to albuminoid ammonia and the presence of bacteria of fecal origin. Marked seasonal variations of the parameters were also observed.