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).

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 energy 2 .
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 production 3 .The mining and associated activities deteriorate the ambient air quality through the emissions of particulate matters (PM), sulfur dioxide (SO 2 ) and nitrogen dioxide (NO 2 ) 4 .This coal field is also of great concern because of the mine fires, spread over an area of approximately 18 km 2 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 (PM 10 and PM 2.5 ) 5,6,7,8,9,10,11 , oxides of nitrogen (NO X ) 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 metals 13 and toxic organic compounds.Metals associated with respirable particles have been shown to increase lung and cardiopulmonary injuries in humans 14 .Particulate matters also reduce visibility and adversely affect surrounding flora and fauna 15,16 .
T h e h u g e i m p a c t s o f m i n i n g a n d 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 13 th 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 India 17 .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 PM 10 , PM 2.5 , SO 2 and NO X .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 XIV 18 .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).

MeThoDoloGy
The study was conducted during Winter (January-February) and Summer seasons (April-May) in the year 2015, with respect to PM 10 , PM 2.5 , SO 2 and NO X .The samples were collected on 24 hourly basis at 4 different locations once a week.Ambient samples of PM 10 were collected by resipirable dust sampler (Envirotech APM 460 NL) (flow rate of 1.1 m 3 min -1 ) on Whatman glass fiber filters and PM 2.5 samples were collected by fine particulate sampler (Envirotech APM 550 MFC) (flow rate 16.7LPM) on PTEF filter papers.The samples of SO 2 and NO X were collected by thermo-electrically cooled gaseous samplers (Envirotech APM 411 TE) through wet chemical method.SO 2 , present in the ambient air is absorbed (flow rate 0.4 LPM) in a of solution 0.04 M potassium tetrachloromercurate (K 2 HgCl 4 ) to form non-volatile dichlorosulfitomercurate (HgCl 2 SO 3 ) and analyzed by following the improved West and Gaeke method 19 .The NO X concentration in ambient air, was determined by absorbing the NO X by a solution of 0.4% sodium hydroxide (NaOH) and 0.1% sodium arsenite (NaAsO 2 -) with a flow rate 0.5 LPM to form sodium nitrite (NaNO 2 ) and analyzed by following the modified Jacob and Hochheiser method 20 .

reSulTS AnD DISCuSSIon
The concentration levels of PM 10 , PM 2.5, SO 2 and NO X at four selected monitoring locations during winter and summer seasons is presented  2. The results reveal a significant variation in pollutant concentrations (PM 10 , PM 2.5 , SO 2 and NO X ) in mining area and along traffic routes.The PM 10 concentrations were observed highest in the mining area (at Dhansar PS) during the study period (291 µg/m 3 during winter and 281 µg/m 3 during summer), followed by traffic routes (Bank More, Shramik Chowk and ISM Gate).The concentration levels of PM 10 were found exceeding the NAAQS by the factor of 2.9, 2.9, 2. Unlike PM 10 , the concentrations of PM 2.5 were observed higher along the traffic routes (highest at Bank More; 218 µg/m 3 during winter and 119 µg/m 3 during summer), followed by mining area (Dhansar PS).The PM 2.5 concentrations were found to be exceeding the NAAQS (60 µg/ m 3 ) 21 by the factor of 3.7, 3.4, 2.3 and 2.2 at Bank More, Shramik Chowk, ISM Gate and Dhansar PS, respectively during winter season.While, during the summer season, the PM 2.5 concentration were observed to be 2.0, 1.8, 1.8 and 1.6 times higher than NAAQS at Bank More, Shramik Chowk, ISM Gate and Dhansar PS, respectively.The exceedance of PM 2.5 at the monitoring locations is attributed to the substantial influence of vehicular emissions at the sites.Because, fine particles are primarily generated from fossil fuel combustion processes and vehicular emission is its leading source in the urban areas.The elevated concentrations of PM 10 and PM 2.5 , indicates a significant impact of mining and transportation activities on the ambient air quality of the area under consideration.
The seasonal variation in concentration of pollutants under consideration (PM 10 , PM 2.5, SO 2 and NO X ) is also quite evident.The concentrations of each pollutant was observed higher during the winter, than the summer season, at all sites.Higher concentration during winter is attributed to the prevalence of anti-cyclonic conditions, characterized by calm or light winds and limited mixing depth due to a stable or inversion of atmospheric lapse rate 22 .The respective mean concentrations of PM 10 and PM 2.5 in the study area were observed 267 µg/m 3 , 173 µg/ m 3 during winter and 234 µg/m 3 , 108 µg/m 3 during summer.Whereas, the mean concentration levels of SO 2 and NO X were observed 40 µg/m 3 , 66 µg/m 3 and 28 µg/m 3 , 56 µg/m 3 during winter and summer seasons, respectively.Similar trends of seasonal variation in particulate matter concentrations were also observed in different areas of India such as Jharia Coalfield 23 , around Dhanbad city 24 , around Dhanbad city 4 , Sambalpur region 22 and Raniganj-Asansol area 25 .
For better understanding and interpretation of the pollution levels as well as to identify the levels of health concern, air quality index (AQI) was calculated and selected monitoring stations were categorized accordingly on the seasonal basis.The indexing was done by following the Indian National Air Quality Index (INAQI) 26 .The calculated AQI for each monitoring station is depicted in Table 3.The AQI values with respect to PM 10 were found poorly polluted at Dhansar PS as well as Bank More and were found moderately polluted at ISM Gate, during both seasons.Whereas, Shramik Chowk was observed poorly polluted during winter and moderately polluted during the summer season.The air quality status with respect to PM 2.5 was observed moderately polluted at all monitoring stations during both seasons.While, with respect to SO 2 and NO X , the air quality status was found satisfactory and good.The observed AQI values and the respective categories illustrate that Dhansar PS and Bank More are the most polluted sites and PM 10 is the most alarming pollutant.

ConCluSIonS
The aim of this study was to investigate the ambient air quality of Dhanbad city with respect to PM 10 , PM 2.5 , SO 2 and NO X monitored at four representative locations.The spatial and seasonal variations in pollutant concentrations were quite significant, which may be caused by diversity among emission sources and prevailing meteorological conditions.From the observation, PM 10 and PM 2.5 were found as major pollutants to be concerned, because, the concentration levels of PM 10 as well as PM 2.5 at all monitoring stations exceeded the NAAQS (2009) annual permissible limit.The concentration of SO 2 was observed highest at Dhansar PS (73 µg/m 3 ), whereas NO X concentration was observed highest at Bank More (92 µg/m 3 ), which may be attributed to mine fire and vehicular emissions, respectively.Air quality index (AQI) was also calculated by following the National Air Quality Index (NAQI CPCB, 2014).The air quality index revealed that, the airshed of the area is moderately to poorly polluted with respect to PM 10 and PM 2.5 , while good to satisfactory with respect to SO 2 and NO X .From the careful observation of the AQI values and its respective categories, Dhansar PS and Bank More are found most polluted sites and PM 10 is identified as the most alarming pollutant in the area under investigation.Based on the observations, the study portrays the need of detailed time series study of pollutant concentrations, source apportionment study of particulate pollutants (to understand the source profile) and study on dispersion characteristics of the airshed in the future.

7 and 2 . 2 (
100 µg/m 3 ) 21 at Dhansar PS, Bank More, Shramik Chowk and ISM Gate, respectively during winter season.While, during the summer season the PM 10 concentrations were observed 2.8, 2.5, 2.4 and 1.7 times higher than the NAAQS at the respective sites.The higher concentration of PM 10 at Dhansar PS is attributed to dust emanated from closely situated open cast coal mines and extensive movement of small and heavy duty vehicles (mining as well as nonmining).Whereas, vehicular emissions (especially resuspension of settled dust particles) are the prime source of elevated concentrations of PM 10 at Bank More and Shramik Chowk.Shramik Chowk and Bank More are the two busiest traffic junctions in Dhanbad city.The heavy movement of vehicles and restricted ventilation condition (due to closely surrounding buildings) makes the site seriously polluted.

Table 3 : Spatial variation in air quality index (AQI) with respect to PM 10 , PM 2.5 , So 2 and no X during winter and summer seasons
Orange: Poorly polluted, Violet: Moderately polluted Light green: Satisfactory, Green: Good in Table