K. V. George

PM10 in the ambient air of Chandrapur coal mine and its comparison with other environments

This study compares the ambient air particulate matter (PM10) data of 15 different coal mine environments. For most of these mine environments, the monitoring was carried out by different researchers using respirable dust sampler (RDS) that separates PM10 by centrifugal inertial separation. At two sites — Padmapur and Ghugus (Chandrapur, Maharashtra, India) — mass inertial impaction-based sampler was used for PM10 monitoring. It is observed that the spatiotemporal average value of ambient air PM10 monitored using mass inertial impactor reports relatively higher values (240–372 μg/m3) compared to those monitored using RDS (<227 μg/m3). In order to realize the severity of mine area pollution, it is compared with PM10 values found in an urban area (Delhi, India). It is found that PM10 values in Delhi (using mass inertial impactor) are much higher (300–400 μg/m3) than those reported for the mine environment. The data seems to indicate that the mine environment is relatively cleaner than urban air and therefore raises doubt about the appropriateness of using either mass impactor or RDS for PM10 sampling.

SIMULATING WATER MOVEMENT AND ITS UPTAKE BY PLANT ROOTS IN UNSATURATED ZONES

Existing mathematical models that simulate water movement and contaminant transport in unsaturated zone do not take into account the water uptake by plant crop roots resulting in an error in the prediction of water flux and, thereby, contaminant concentration. Moreover the application of these models is often limited due to the lack of easily accessible and representative soil hydraulic properties, like moisture retention characteristic and unsaturated hydraulic conductivity. In this study, a mathematical model is developed for simulating water movement in unsaturated zones by integrating the one‐dimensional transient unsaturated water flow equation (Richards equation) with a root water extraction term (sink), and also incorporates pedo‐transfer functions (PTF) for estimating soil hydraulic properties. The governing non‐linear partial differential equation is solved numerically by the implicit finite difference method using Picards iterative technique, the formulation has been illustrated by a characteristic example.

Evaluation of coarse and fine particles in diverse Indian environments

The estimates of airborne fine particle (PM2.5) concentrations are possible through rigorous empirical correlations based on the monitored PM10 data. However, such correlations change depending on the nature of sources in diverse ambient environments and, therefore, have to be environment specific. Studies presenting such correlations are limited but needed, especially for those areas, where PM2.5 is not routinely monitored. Moreover, there are a number of studies focusing on urban environments but very limited for coal mines and coastal areas. The aim of this study is to comprehensively analyze the concentrations of both PM10 and PM2.5 and develop empirical correlations between them. Data from 26 different sites spread over three distinct environments, which are a relatively clean coastal area, two coal mining areas, and a highly urbanized area in Delhi were used for the study. Distributions of PM in the 0.43–10-μm size range were measured using eight-stage cascade impactors. Regression analysis was used to estimate the percentage of PM2.5 in PM10 across distinct environments for source identification. Relatively low percentage of PM2.5 concentrations (21, 28, and 32%) in PM10 were found in clean coastal and two mining areas, respectively. Percentage of PM2.5 concentrations in PM10 in the highly urbanized area of Delhi was 51%, indicating a presence of a much higher percentage of fine particles due to vehicular combustion in Delhi. The findings of this work are important in estimating concentrations of much harmful fine particles from coarse particles across distinct environments. The results are also useful in source identification of particulates as differences in the percentage of PM2.5 concentrations in PM10 can be attributed to characteristics of sources in the diverse ambient environments.

Study for reclamation of land occupied by solar evaporation pond at UCIL, Bhopal, India

Solar Evaporation Ponds (SEP) were used by Union Carbide India Limited (UCIL), Bhopal for storage of wastewater containing high concentrations of inorganic chemicals especially chlorides. Area occupied by the SEPs had to be recovered due to closure of the plant. A prerequisite to the reclamation of the SEP area is a study of adjoining soil and groundwater, which may be contaminated due to possible leakage in the pond. Surface soil, subsurface soil and groundwater samples were collected and analysed. The electrical conductivity method was employed inside the pond to test for leak in the geo-membrane liner. This was further confirmed by physically checking the liners. Based on the wet period, total rainfall and evaporation rate of the region, drying of remaining wastewater by spreading in dry ponds followed by pond dismantling was scheduled.