Investigation of Impacts of Mining and Transportation Activities on Ambient Air Quality of Dhanbad City

The present study was intended to emphasize the assessment of ambient air quality of Dhanbad city with respect to PM10, PM2.5, SO2 and NOX concentrations, in order to investigate the impact of mining and transportation activities. From the monitoring and analysis at four selected monitoring stations during winter and summer seasons, significant spatial variation in pollutant (PM10, PM2.5, SO2 and NOX) concentrations is quite evident. The concentrations of PM10 were observed highest in mining area (at Dhansar PS; 291 μg/m3), whereas the PM2.5 the concentrations were observed higher along traffic routes (especially, at Bank More; 218 μg/m 3). Higher concentratios of PM10 in mining area indicates the substantial impact of dust emanated from mining and associated activities on air quality. Whereas, the higher PM2.5 concentration along the transportation routes shows the influence of transportation activities on the airshed of the area. The significant seasonal variation in pollution levels is also apparent, as the concentrations of every pollutant were observed higher during the winter, than the summer season, at all sites. The mean concentration levels of PM10 and PM2.5 were observed 267 μg/m 3, 173 μg/m3 and 234 μg/m3, 108 μg/m3 during winter and summer seasons, respectively. From the calculated values of air quality index, it is evident that Dhansar PS and Bank More are most polluted sites and PM10 is the most alarming pollutant in the area under investigation. key words: Air quality, AQI, PM10, PM2.5, summer, winter. Air pollution is a major concern before scientific communities and policy makers all over the world, especially in developing countries. With the rapid growth in population, urbanization, industrialization and economic growth, there is a steady surge in demand of mining and energy sectors. This puts a substantial pressure on the environmental regime, particularly on the ambient air. The mining and energy industries are the foremost sectors responsible for the severe deterioration in air quality besides their significant contribution to the economic development. At present, energy is chiefly produced by fossil fuels (coal, petroleum oil and natural gas)1. Among these, coal is the most abundantly present and cheapest source of energy2. Jharia coal-field (JCF) located in Dhanbad, is one of the most important and the most exploited coal-field of India because of available metallurgical grade coal reserves. Jharia coal-field is subjected to intensive mining activities and accounts for 30% of the total Indian coal production3. The mining and associated activities deteriorate the ambient air quality through the emissions of particulate matters (PM), sulfur dioxide (SO2) and nitrogen dioxide (NO2) 4. This coal field is also of great concern because of the mine fires, spread over an area of approximately 1023 JENA et al., Curr. World Environ., Vol. 10(3), 1022-1028 (2015) 18 km2 4. Besides mining and energy sector, another most important activity, deteriorating air quality is vehicular transportation. Vehicular (Paved/unpaved) transportation is known to contribute a considerable load of particulate matter (PM10 and PM2.5) 5, 6, 7, 8, 9, 10,11, oxides of nitrogen (NOX) 12. Particulate matters are pollutants of major concern because of its diverse nature (size and composition) and complexity of sources. The particulate matters carry toxic pollutants such as heavy metals13 and toxic organic compounds. Metals associated with respirable particles have been shown to increase lung and cardiopulmonary injuries in humans14. Particulate matters also reduce visibility and adversely affect surrounding flora and fauna15, 16. The huge impacts of min ing and transportation activities on the ambient air quality obligates the assessment pollution levels in this area. Further, this area (Dhanbad) is declared as a critically polluted area and ranked 13th among 88 industrial areas, with a score of 78.60 out of 100 by Central Pollution Control Board (CPCB) in consultation with the Ministry of Environment and Forests, Government of India17. The objective of the study was to investigate the scenario of air pollution in mining and urban areas of Dhanbad in order to assess the impact of the dominant anthropogenic activities (mining and transportation) on ambient air quality. For the assessment, the monitoring was done during winter and summer seasons at four selected monitoring stations with respect to PM10, PM2.5, SO2 and NOX. Based on the observed concentration of pollutants, air quality index (AQI) values were also estimated for better understanding and interpretation of the pollution levels. Study area Dhanbad is the third largest city in Jharkhand State and is known as the coal capital of India. It lies between 23°37’3" N to 24°4’ N latitude and between 86°6’30" E to 86°50’ E longitude, having an mean elevation of 222 m. Dhanbad is situated in the subtropical climatic zone and and experiences a cool winter and hot summer season. The temperature varies approximately between 11°C to 22°C during winter and 25°C to 45°C during summer season. This region receives heavy rainfall (approximately 1300 mm) annually. Open-cast coal mines, coal washeries, coke oven plants, mine fires as well as transportation (mining and non-mining) activities are the major sources of air pollution in this city. For the purpose of systematic ambient air quality monitoring, four (4) representative monitoring stations were selected in the study as per the siting criteria provided by IS: 5182 Part XIV18. The details of monitoring stations are presented in Table 1 and Figure 1. Among the four stations, Dhansar P.S. represents a mining area and Bank More, Shramik Chowk and ISM Gate represent traffic routes. Bank More and Shramik Chowk are traffic junctions (dominated by the heavy load of vehicular traffic) and also commercial as well as residential areas. ISM Gate is a institutional as well as residential area (dominated by moderate loads of vehicular traffic).