Assessment of Ambient Air Quality at Joda Iron Ore Mines, Jharkhand (India)

Opencast mining is the major source of air pollution in respect of fines and dust. Maintenance of energy demand, opencast mining is required at a phenomenal rate. The natural resources like land, water, air are heavily affected by exploration, excavation and mineral processes. The use of explosives creates airborne pressure variations (air blast). Particulate matter (Dust) of various sizes, gas is the major air pollutant from mining. The study aimed to assess the impact of mining and mining processes on ambient air quality in Joda iron ore mines, which comes under OMQ Noamundi, TATA Steel Ltd., West Singhbhum, and Jharkhand covering an area of 6.708 sq. km. It is a mechanized open cast mine, and its production capacity is 6.00 million tons per annum. Samples were collected from four sampling points by residential and sensitive zone to analyse the PM10, PM2.5, SPM, SO2, and NOX on 24 hourly bases twice in a week. The concentration of PM10, PM2.5, SPM, SO2 and NOX varies between 59.0-27.0 μg/m3, 39.0-9.5 μg/m3, 183-109 μg/m3, 9.9-8.0 μg/m3 and 10.2-8.2 μg/m3 respectively. Due to the presence of pollution control equipment and techniques as sprinklers, dry fog system, and dust extractor, etc., air pollutants are within the permissible limit of National Ambient Air quality standards (2009). Dust was the single largest air pollutant observed in the study area.


INTRODUCTION
Extraction of non renewable resources can be termed as mining. The mineral industry in India is reckoned not only as an essential backbone of a contributor to the country's GDP and foreign trade, but it is also one of the major sectors that engage a large of employment of the country's working population [1]. Mining activity is either surface mining or sub-surface (underground) mining. The mining life cycle during the temporary use of the land appear divided into many phases. The perturbation of the environment starts with the extraction of these resources by the mining industry units.
After the extraction and mechanical preparations, the iron ores are transported to the users with conveyor dump track belts and train sets. Both the loading and discharge threatens, and during the transportation, the environment is decayed because of [2], [3] the dispersal of powder at handling, under the effect of air currents, water and the forces that interfere during transportation.
The surface mining influences the environment up to a complex level. It also influences the further modification of the environment and results in deterioration of the health conditions of the inhabitants of the industrial regions and the reincorporation occurs within the economic circuit of the degraded lands. Geomorphological structure of the occupied land gets modified due to surface exploitation which also makes cultivation impossible for an extended period. The mining constructions and installations that often constitute the cause of the hydrographic changes of the surrounding lands and are sometimes pollution sources of the atmosphere and waters. The most severe effect of the mining exploitation is the elimination of the economic circuit of more geographical areas, and the reduction of the production capacity of some limit lands [4], [5].

FRAMEWORK OF RESEARCH METHODOLOGY Study Area
The study area was Joda iron ore mines, OMQ, Noamundi, TATA Steel Ltd, West Singhbhum, and Jharkhand. Joda east lease block, covering an area of 6.708 sq. Km. It is a mechanized open cast mine with an annual production capacity of 6.00 million tonnes. 4 type of principal that is hematic ores dominant in this area, i.e., hard ore, soft ore, friable flaky ore and blue dust.

Geology
The formation containing iron ore deposits belongs to the late Archean iron ore series. These deposits have been molded under marine conditions. The origin of iron seems to be weathering of continental rocks under reducing atmospheric conditions which were prevalent during the early Archean age. It consists of an undulating surface with steep to a gentle slope and reddish yellow to the chocolate colour soil. Reserve forest exits in the area.

Metrological Condition
The dry tropical climate of the area has four seasons during the year. During summer months temperature goes up to 47 0 C and in winter it falls to as low as 10 0 C. Annual mean maximum temperature is 33.2 0 C and minimum temperatures is 20.5 0 C. During the winter season the wind speed (km/h) and its direction were monitored to find out the maximum impact of air qualities. In all the directions average values were also calculated for three significant ranges. It was observed during the study that the prevailing wind direction at that time was northwest.

Mining Activities or Sources
Several mining activities or sources are considered to study the emission estimation in open cast mining. These activities or sources may be categorized as a point, line, and area sources. Different mining activities as drilling, loading and unloading, handling and different sources like haul road, transport road, exposed pit surface, overburden dumps, stockyards and workshops are considered for the present study.

Air pollution control equipment and prevention techniques
The mechanized open cast mines results in more environmental pollution as they are becoming, broader, deeper and more capital intensive. Continuing efforts have been made to improve ambient air quality condition upon the open cast mining activities. A management strategy and other mitigative measures as green belt designs were framed for effective control of air pollution at source, and for sensitive areas [6].
Some pollution prevention measures and techniques were employed which are mobile water sprinkler, fixed water sprinkler, dry fog system at the primary crusher, dust extractor at the primary crusher, wet drilling, the addition of dust suppressant in sprinkling water, wet processing of iron ore and transportation by conveyors.
Samples for PM 10 , PM 2.5 , SPM, SO 2, and NO X were collected, preserved,

RESULT AND DISCUSSIONS
The ambient air quality is reduced due to natural phenomena and anthropogenic activities. Gases such as CO, SO 2 , NO x , H 2 S, etc. these pollutants are continually formed into the atmosphere through natural activities such as volcanic eruptions, sunshine, and vegetation decay and forest fire. Presences of air pollutants, present in the atmosphere affect the men and his environment by disturbing the dynamic equilibrium of atmosphere. The collected and analyzed data from ambient air of Joda iron ore mines are given below in Table 1.

Suspension Powders
More and more suspension powders concentration was found at different locations as at excavation area, at devastation on the conveyor belt, at the devastation from one to another, belt of auto transportation, at the platforms of iron ore loading in the train wagon. Dust is being produced through a number of mechanisms [7] which cause damage of lung tissues, tissues, black lung disease, poor visibility, increased maintenance cost which lowers the productivity [8].

Variation in Particulate Matter PM 10
The Fig. 1 shows the maximum and minimum concentrations were found to be 59.0 µg/m 3 and 27.0 µg/m 3 at mining area and near residential housing respectively.

Figure 1: Concentration level of PM 10 at monitoring sites.
An average level of concentration at different sites as primary crusher, mining area, electrical substation and near the residential house were 48.8, 49.1, 36.38 and 33.0 µg/m 3 respectively as shown in Fig. 1. At all points, the concentration of PM 10 were under the permissible limit due to the presence of pollution prevention techniques. Fig. 2 shows variation in average concentration of PM 2.5 as 27.9, 28.5, 17.13, and 13.3 µg/m 3 at the primary crusher, mining area, and electrical substation and near residential housing respectively. The maximum concentration of PM 2.5 was found to be 39 µg/m 3 at mining site which was under the permissible limit. PM 2.5 concentration was under the desirable limit due to the application of water sprinkles, conveyor system, wet drilling and dust extractor.

Variation in Suspended Particulate Matter (SPM)
The maximum concentration of SPM at mining area found to be 183 µg/m 3 due to the vehicular movement for transportation of ores, drilling, blasting, excavation of ores. The concentration of SPM was under permissible limit due to the application of pollution prevention equipment as mobile sprinkles, fixed sprinkles wet drilling conveyor system for transportation of ore. Average concentrations of SPM at the primary crusher, mining area, electrical substation, near the residential house were 167, 169, 134, and 121 µg/m 3 respectively as shown in Fig. 3.

Gaseous Pollutants
The impact brought over the air was produced by [6], [9] the gaseous SO 2 and NOx which is the result of transportation and the operation of heaping of the sterile material and with the internal combustion of the user equipment. The acoustic emissions with different origins, provided by the technological machine or by the means of transportation.

Trends of SO 2
Average concentrations of SO 2 vary as 9.43, 9.51, 9.74, 9.0, and 8.38 µg/m 3 at the primary crusher, mining area, electrical substation and residential housing respectively as shown in Fig. 4. The maximum concentration of SO 2 occurs at mining area was found to be 9.9 µg/m 3 due to mining process as drilling, blasting, excavation, vehicular pollution of dumpers. Sources of SO 2 emission at primary crusher were vehicular movement, crushing of boulders and at electrical substation, the only source was vehicular pollution.

CONCLUSIONS
The extraction and exploration from the mining of iron ores affect the quality of the areal area. The quality of air was affected by the suspension, sedimentary powder and gases resulted from the extraction activity, transportation, and deposition of the iron ore. In Joda iron ore mines the maximum concentration of PM 10 , PM 2.5 , SPM, SO 2 , and NOx ranges between 39-59 µg/m 3 , 17 -39 µg/m 3 , 131-183 µg/m 3 , 8.7-9.9 µg/m 3 and 8.9 -10.2 µg/m 3 respectively. These values of all parameters are under the permissible limit of National Ambient Air quality standards (2009) as PM 10 -100 µg/m 3 , PM 2.5 -60 µg/m 3 , SPM-500 µg/m 3 , SO 2 -80 µg/m 3 , and NOx-80 µg/m 3 . The adoption of some tools and techniques efficiently reduces the negative impact that the mines have over its environment.