Padma S. Rao

Emission, speciation, and evaluation of impacts of non-methane volatile organic compounds from open dump site

Surface emission from Dhapa, the only garbage disposal ground in Kolkata, is a matter of concern to the local environment and also fuels the issues of occupational and environmental health. Surface emission of the Dhapa landfill site was studied using a flux chamber measurement for nonmethane volatile organic compounds (NMVOCs). Eighteen noncarbonyl volatile organic compounds (VOCs) and 14 carbonyl VOCs, including suspected and known carcinogens, were found in appreciable concentrations. The concentrations of the target species in the flux chamber were found to be significantly higher for most of the species in summer than winter. Surface emission rate of landfill gas was estimated by using two different approaches to assess the applicability for an open landfill site. It was found that the emissions predicted using the model Land GEM version 3.02 is one to two orders less than the emission rate calculated from flux chamber measurement for the target species. Tropospheric ozone formation has a serious impact for NMVOC emission. The total ozone-forming potential (OFP) of the Dhapa dumping ground considering all target NMVOCs was estimated to be 4.9E+04 and 1.2E+05 g/day in winter and summer, respectively. Also, it was found that carbonyl VOCs play a more important role than noncarbonyl VOCs for tropospheric ozone formation. Cumulative cancer risk estimated for all the carcinogenic species was found to be 2792 for 1 million population, while the total noncancer hazard index (HI) was estimated to be 246 for the occupational exposure to different compounds from surface emission to the dump-site workers at Dhapa. Implications: This paper describes the real-time surface emission of NMVOCs from an open municipal solid waste (MSW) dump site studied using a flux chamber. Our study findings indicate that while planning for new landfill site in tropical meteorology, real-time emission data must be considered, rather than relying on modeled data. The formation of tropospheric ozone from emitted NMVOC has also been studied. Our result shows how an open landfill site acts as a source and adds to the tropospheric ozone for the airshed of a metropolitan city.

Effects of unregulated anthropogenic activities on mixing ratios of volatile organic air pollutants—A case study

During the months of October to November, many important festivals are celebrated in India. Celebration of these festivals are marked by extensive use of fireworks or pyrotechnics, bonfire, incense burning, open air community cooking, and temporary eateries using crude fuel such as coal, wood, kerosene, cow dung, burning of raw/semiwood, and coconut shells. The present study deals with the influence of these unregulated anthropogenic activities on ambient mixing level of volatile organic compounds (VOCs), especially some carbonyl compounds. The study was undertaken in the metropolitan city of Kolkata, India, with very high population density, which is even higher during festival period. The average total carbonyl level at different sites in Kolkata varied from 134.8 to 516.5 μg m−3 in pre-festival season, whereas in post-festival season the same varied from 252.2 to 589.3 μg m−3. Formaldehyde to acetaldehyde ratio altered from 0.62 in pre-festival season to 1.78 in post-festival season. Diurnal variation also altered, indicating variation in source composition of carbonyls. The total ozone forming potential calculated for all 14 carbonyls in pre-festival season increased by 35% in post-festival season. The effect of anthropogenic activities typical to the event of Diwali night characterized by intense execution of pyrotechnics resulted in significantly high level of carbonyl VOCs. Principal component analysis study for the event of Diwali shows clear contribution of the event on certain carbonyl VOCs. The results indicate elevated primary emissions of these pollutants and also their effect on formation of secondary pollutants. The study emphasizes the need of generating awareness among the communities in society as well as need for regulations to minimize the emissions and related hazards to the extent possible. Implications: Altered anthropogenic activities typical of festival season including extensive use of pyrotechnics affect ambient level of volatile organic compounds, especially some carbonyls. Such activities have considerable effect on interspecies ratio and diurnal variation. They also affect formation of secondary pollutants such as tropospheric ozone. Principal component analysis (PCA) study shows clear contribution of the pyrotechnics execution on certain carbonyl VOCs. The findings emphasize the need of generating awareness in society and need for regulations to minimize the emissions.

Prediction of remotely sensed cloud related parameters over an inland urban city of India: a neuro-computing approach

ABSTRACT Artificial neural network (ANN) is a mathematical model useful for forecasting on the any type of available data. This tool is not only useful in environment but also covers wide ranges of applicability. Utilizing this model, a study was carried out in an inland area of Nagpur for forecasting satellite-derived cloud parameters. Nine ANN architects are developed based on five pollutant parameter (aerosol optical depth, RSPM, SPM, SO2, NOx), meteorological and some cloud parameter. The models are used to simulate concentration of pollutants as well as the forecast and validation of cloud top temperature, cloud ice water path and cloud liquid water path during different seasons (winter, pre-monsoon and post-monsoon). Models based on back-propagation neural network were tested using the collected data of study area. The ANN models were trained using gradient descent algorithms to check the robustness and adaptability of the models. ANN models based on both satellite and ground-based data variables demonstrate the best performance and are skilled at resolving patterns of pollutant dispersion to the atmosphere during 2006–2013 for Nagpur city.

Environmental impact of plantations in and around the petroleum refinery: a case study

Plantation or green belt (GB) grown around the factories and industrial premises improves the condition of land, mitigates air pollution (as the plants serve as a sink for pollutants and check the flow of dust, etc.), and reduces the level of noise pollution. The software developed by NEERI for the determination of the optimal width of GB in and around an industry is based on the pollution attenuation coefficient of selected plant species of deciduous trees existing in the region. The assessment of the impact of these plantations/green belts of 500-m width in and around a petroleum refinery in the west coast of India is evaluated for reducing/managing various waste generated, and it is observed that the overall efficiency is more than 60%.