The coal is contaminated with toxic metals at the trace levels. They are released into the environment during mining, handling and burning of coal. The Korba basin has one of the largest coal exploitation areas in the country. In this work, contamination and sources of toxic metals i.e. Hg and Pb in the air, soil and sediment of the Korba basin, India are described. The concentration of Hg and Pb in the ambient air was ranged from 7.4 - 29 and 7.0 - 585 ng/m
3 with mean value of 18 ± 4 and 129 ± 104 ng/m
3 in the winter season. The mean concentration of Hg in the soil and sediment was 0.22 ± 0.03 and 0.44 ± 0.08 mg/kg, respectively. The higher concentration of Pb in the environmental samples was observed.
Lead Mercury Aerosol Soil Sediment1. Introduction
Heavy metals i.e. Pb and Hg are highly toxic to the developing brain and nervous system [1] -[2] . Coal is a naturally occurring combustible fuel containing the toxic metals at trace levels [3] -[5] . They are emitted from the thermal power plant stacks in both gaseous and particulate forms by retaining some fractions in the ash residues [6] -[8] . They are persistent in the environment, could enter bodies through the oral route and prove a great threat to people, especially those living in the vicinity of these thermal power plants. The contamination of environment with the Pb and Hg in various parts of the World was reported [9] -[45] . In the present work, contamination, enrichment and sources of Pb and Hg in the environment of the Korba basin, India are described.
2. Methods and Materials2.1. Study Area
The Korba basin (22˚21'N, 82˚40'E) has largest coal deposit in the country extending over ≈530 km2. Several open and underground coal mines are in operation with production of >10,000 MT/Yr coal. They are consumed by the thermal power plants running in the basin for production of electricity (40,000 MW) by pouring effluents into the environment. The population (≈0.5 million) of the basin is exposed severely with particulate and fly ash pollution. The increased prevalence rate of air and water borne diseases in human and domestic animals was observed.
2.2. Sample Collection and Meteorological Analysis
The sampling network for collection of particulate matters (PM), soil and sediment is shown in Figure 1. The Lata Envirotech air sampler was used for the collection of the coarse particulate matters (PM10). The PM10 was collected over the quartz filer paper (47-mm, Whatmann) at flow rate of 16 lit/min. The sampler was run for duration of 24 hr at the 1st floor of the building (≥3 m above the ground level). Ten samples were collected from 10 different locations of the Korba basin during period: December, 2012-February, 2013.
Representation of sampling locations
The Anderson sampler (1531-107B-G289X) with eight stages: PM10.0-9.0, PM9.0-5.8, PM5.8-4.7, PM4.7-3.3, PM3.3-2.1, PM2.1-1.1, PM1.1-0.7 and PM0.7 was used for the collection of respirable particulate matters in the segregation forms. The sampler was run for 72 hr at four locations in January, 2013. The mass of dried loaded and blank filters were weighted out.
The surface soil (0 - 10 cm) samples from 30 locations of the basin were collected in January, 2013 [46] . The pond sediment was sampled from 26 locations of the basin in January, 2013 [47] . They were dried, crushed and sieved out particles of ≤0.1 mm sizes. The meteorological parameters i.e. ambient temperature (T), humidity (H), wind speed (WS) and wind direction (WD) were measured during the sampling period.
2.3. Analysis
The weighed amount of the sample was digested with acids by the microwave probe by using prescribed procedure. The Pb and Hg contents were analyzed by the Varian GF-AAS and CV-AAS techniques. The elemental or black carbon (BC or EC) and organic carbon (OC) were analyzed by the thermal and titration methods [48] . The pH value of soil and sediment extracts was determined, by shaking the soil or sediment sample in a 1:2 volume ratio with the deionized water.
3. Results and Discussion
The atmosphere of Korba basin is dusty due to huge emission of coal and ash particulates. The meteorology of the studied area during the winter period (2012-13) is summarized in Table 1. The value of T, H and WS was ranged from 8˚C - 30˚C, 24% - 93% and 3 - 8 k/hr, respectively during the studied period. The air mass flow was varied from E to S with domination in the SE direction.
3.1. Distribution of PM in ambient air
The distribution of the PM in the ambient air is summarized in Table 2. Extremely high concentration of PM10 in ambient air during the winter period was observed, ranging from 196 - 775 µg/m3 with mean value of 390 ± 137 µg/m3. The highest concentration of the PM10 was observed at location No. 2 due to input of the thermal power plant (TPP) effluents. The segregation chromatogram of the PM10 at four locations is summarized in Figure 2. The mean (n = 4) relative concentration of PM10.0-9.0, PM9.0-5.8, PM5.8-4.7, PM4.7-3.3, PM3.3-2.1, PM2.1-1.1, PM1.1-0.7 and PM0.7 in the air was 17, 14, 9, 9, 15, 19, 12 and 6%, respectively. At least, 52% ± 14% PM lie in the fine and ultrafine modes (≤3.3 µm). The concentration of respirable PM in the air was found to be too much higher than recommended limit of 50 µg/m3 [49] .
Meteorology of the studied area
S. No.
Sampling location
Sampling date
Temperature (T) ˚C
Humidity (H), %
WS km/hr
WD
Min
Max
Min
Max
1
Korba city
26-12-2012
8
25
32
61
4
E
2
ITI colony
27-12-2012
11
27.5
54.5
77
4.5
SE
3
CSEB colony
01-01-2013
17.5
27.5
65
92
4.5
E
4
Manikpur
02-01-2013
10.5
24
27
47
8
SE
5
BALCO
05-01-2013
8.5
23.5
35
69
3
SW
6
Kusmunda
06-01-2013
14.5
29.5
40
65
3.5
NW
7
Niharika
08-01-2013
14
26.5
33
55.5
4
SE
8
Darri
09-01-2013
15
27
28
47.5
4
SE
9
Mudapar
13-01-2013
8
26
24
49
4
SE
10
Banki
14-01-2013
30
30
35
57
4
SE
E = East, S = South, W = West, N = North.
Segregation of PM<sub>10</sub> in ambient air of Korba
Concentration of EC, Pb and Hg in ambient air and PM
S. No.
PM10, µg/m3
EC concentration
Pb concentration
Hg concentration
Ambient air, µg/m3
PM, %
Ambient air, ng/m3
PM, mg/kg
Ambient air, ng/m3
PM, mg/kg
1
315
26
8.2
101
320
18.8
59.7
2
775
68
8.8
585
755
18.0
23.3
3
196
16
8.2
109
556
7.4
37.7
4
226
18
7.9
83
368
17.2
76.2
5
209
16
7.5
59
280
15.0
71.8
6
319
19
6.1
7.0
22
17.0
53.3
7
283
22
7.7
71
252
24.3
86.1
8
666
46
6.9
21
31
17.4
26.1
9
666
53
8.0
193
290
29.0
43.5
10
251
18
7.2
60
240
11.7
46.7
3.2. Distribution of Hg in Air, Soil and Sediment
Mercury is a highly mobile metal, being liquid at room temperature, and behaves like organic compounds. The concentration of the Hg (n = 10) in the air (associated to PM10) was ranged from 7.4 - 29 ng/m3 with mean value of 18 ± 4 ng/m3, Table 2. Its concentration in the PM10 (n = 10) was ranged from 23 - 86 mg/kg with mean value of 52 ± 13 mg/kg, Table 2. The higher concentration of Hg was observed in the studied area as compared to other regions of the World (i.e. Canada, China, Korea, Mexico, Taiwan, Thailand and Vietnam), may be due to huge coal burnings [11] -[15] .
All the soil and sediment were composed of micrometer-scale grains with nano-scale structure. They were colored, ranging from whitish (W) to black (B) due to deposition of the fly ash and black carbon, Table 3 and Table 4. The mean pH value of the soil and sediment extracts were found to be slightly acidic, »6.6 due to presence of high content of chloride and sulfate ions. The concentration of Hg in the soils (n = 30) was ranged from 0.11 - 0.39 mg/kg with the mean value of 0.22 ± 0.03 mg/kg. The concentration of Hg in the soil of studied area was found to be comparable to the contents reported in other regions of the World (i.e. China, Greece, Iran, Poland, USA) [16] -[20] .
At least 2-folds higher concentration of Hg in the sediment was observed and may be due to its highly mobile nature. The concentration of Hg in the sediments (n = 26) was ranged from 0.12 - 0.82 mg/kg with the mean value of 0.44 ± 0.08 mg/kg. Extremely high concentration of Hg in the sediment of Hong Kong and Mumbai, maximum up to in the 0.855 - 2.66 mg/kg was reported [21] -[22] . The Hg loading in the sediments of Amazonian basin, Brazil, China, and Poland was ranged from 55 - 386 µg/kg [23] -[28] .
Distribution of Pb and Hg in soil
ReferencesBernhoft, R.A. (2012) Mercury Toxicity and Treatment: A Review of the Literature. Journal of Environmental and Public Health, 2012, 1-10. http://dx.doi.org/10.1155/2012/460508Murata, K., Iwata, T., Dakeishi, M. and Karita, K. (2009) Lead Toxicity: Does the Critical Level of Lead Resulting in Adverse Effects Differ between Adults and Children? Journal of Occupational Health, 51, 1-12. http://dx.doi.org/10.1539/joh.K8003Yudovich, Y.E. and Ketris, M.P. (2005) Mercury in Coal: A Review Part 2. Coal Use and Environmental Problems. International Journal of Coal Geology, 62, 135-165. http://dx.doi.org/10.1016/j.coal.2004.11.003Patra, K.C., Rautray, T.R., Tripathy, B.B. and Nayak, P. (2012) Elemental Analysis of Coal and Coal ASH by PIXE Technique. Applied Radiation and Isotopes, 70, 612-616. http://dx.doi.org/10.1016/j.apradiso.2011.12.013Bhangare, R.C., Ajmal, P.Y., Sahu, S.K., Pandit, G.G. and Puranik, V.D. (2011) Distribution of Trace Elements in Coal and Combustion Residues from Five Thermal Power Plants in India. International Journal of Coal Geology, 86, 349-356. http://dx.doi.org/10.1016/j.coal.2011.03.008Soni, D.K., Chakrabarti, S.P. and Aggarwal, A.L. (2000) Heavy Metal Emission from Thermal Power Plants and its Implication on Vegetative Environment—A Case Study. Environmental Stress: Indication, Mitigation and Eco-Conservation, 153-164. http://dx.doi.org/10.1007/978-94-015-9532-2_14Labus, K. (1995) Heavy-Metal Emissions from Coal Combustion in Southwestern Poland. Energy, 20, 1115-1119. http://dx.doi.org/10.1016/0360-5442(95)00062-LMeij, R. and Winkel, H. (2007) The Emissions of Heavy Metals and Persistent Organic Pollutants from Modern Coal-Fired Power Stations. Atmospheric Environment, 41, 9262-9272. http://dx.doi.org/10.1016/j.atmosenv.2007.04.042Lu, J.Y. and Schroeder, W.H. (1999) Sampling and Determination of Particulate Mercury in Ambient Air: A Review. Water Air and Soil Pollution, 112, 279-295.Keegan, T.J., Farago, M.E., Thornton, I., Hong, B., Colvile, R.N., Pesch, B., Jakubis, P. and Nieuwenhuijsen, M.J. (2006) Dispersion of As and Selected Heavy Metals around a Coal-Burning Power Station in Central Slovakia. Science of the Total Environment, 358, 61-71.Schleicher, N.J., Schäfer, J., Blanc, G., Chen, Y., Chai, F., Cen, K. and Norra, S. (2015) Atmospheric Particulate Mercury in the Megacity Beijing: Spatio-Temporal Variations and Source Apportionment. Atmospheric Environment, 109, 251-261. http://dx.doi.org/10.1016/j.atmosenv.2015.03.018Sheu, G.R., Lin, N.H., Lee, C.T., Wang, J.L., Chuang, M.T., Wang, S.H., Chi, K.H. and Ou-Yang, C.F. (2013) Distribution of Atmospheric Mercury in Northern Southeast Asia and South China Sea during Dongsha Experiment. Atmospheric Environment, 78, 174-183. http://dx.doi.org/10.1016/j.atmosenv.2012.07.002Cairns, E., Tharumakulasingam, K., Athar, M., Yousaf, M., Cheng, I., Huang, Y., Lu, J. and Yap, D. (2011) Source, Concentration, and Distribution of Elemental Mercury in the Atmosphere in Toronto, Canada. Evironmental Pollution, 159, 2003-2008. http://dx.doi.org/10.1016/j.envpol.2010.12.006Ruelas-Inzunza, J., Delgado-Alvarez, C., Frías-Espericueta, M. and Páez-Osuna, F. (2013) Mercury in the Atmospheric and Coastal Environments of Mexico. Reviews of Environmental Contamination and Toxicology, 226, 65-99. http://dx.doi.org/10.1007/978-1-4614-6898-1_3Kim, P.R., Han, Y.J., Holsen, T.M. and Yi, S.M. (2012) Atmospheric Particulate Mercury: Concentrations and Size Distributions. Atmospheric Environment, 61, 94-102. http://dx.doi.org/10.1016/j.atmosenv.2012.07.014Rodriguez Martin, J.A., Nanos, N., Grigoratos, T., Carbonell, G. and Samara, C. (2014) Local Deposition of Mercury in Topsoils around Coal-Fired Power Plants: Is It Always True? Environmental Science and Pollution Research International, 21, 10205-10214. http://dx.doi.org/10.1007/s11356-014-2873-0Liang, Y., Yuan, D., Lu, M., Gong, Z., Liu, X. and Zhang, Z. (2009) Distribution Characteristics of Total Mercury and Methylmercury in the Topsoil and Dust of Xiamen, China. Journal of Environmental Sciences, 21, 1400-1408. http://dx.doi.org/10.1016/S1001-0742(08)62432-8Solgi, E., Esmaili-Sari, A. and Riyahi-Bakhtiari, A. (2014) Spatial Distribution of Mercury in the Surface Soils of the Urban Areas, Arak, Iran. Bulletin of Environmental Contamination and Toxicology, 93, 710-715. http://dx.doi.org/10.1007/s00128-014-1408-1Gray, J.E., Theodorakos, P.M., Fey, D.L. and Krabbenhoft, D.P. (2015) Mercury Concentrations and Distribution in Soil, Water, Mine Waste Leachates, and Air in and around Mercury Mines in the Big Bend Region, Texas, USA. Environmental Geochemistry and Health, 37, 35-48. http://dx.doi.org/10.1007/s10653-014-9628-1Dabkowska-Naskret, H. and Rózański, S.Z. (2007) Mercury Content in Garden Soils of Urban Agglomeration. Global NEST Journal, 9, 237-241.Shi, J.B., Ip, C.C.M., Tang, C.W.Y., Zhang, G., Wu, R.S.S. and Li, X.D. (2007) Spatial and Temporal Variations of Mercury in Sediments from Victoria Harbour, Hong Kong. Marine Pollution Bulletin, 54, 480-485. http://dx.doi.org/10.1016/j.marpolbul.2006.11.016Ram, A., Rokade, M.A. and Zingde, M.D. (2009) Mercury Enrichment in Sediments of Amba Estuary. Indian Journal of Marine Sciences, 38, 89-96.Boszke, L. and Kowalski, A. (2006) Spatial Distribution of Mercury in Bottom Sediments and Soils from Poznań, Poland. Polish Journal of Environmental Studies, 15, 211-218.Laperche, V., Hellal, J., Maury-Brachet, R., Joseph, B., Laporte, P., Breeze, D. and Blanchard, F. (2014) Regional Distribution of Mercury in Sediments of the Main Rivers of French Guiana (Amazonian Basin). Springer Plus, 3, 322. http://dx.doi.org/10.1186/2193-1801-3-322Shreadah, M.A. Ghani, S.A.A., Taha, A.A.E.S., Ahmed, M.M.A.E. and Hawash, H.B.I. (2012) Mercury and Methyl Mercury in Sediments of Northern Lakes-Egypt. Journal of Environmental Protection, 3, 254-261. http://dx.doi.org/10.4236/jep.2012.33032Shao, D., Liang, P., Kang, Y., Wang, H., Cheng, Z., Wu, S., Shi, J., Lo, S.C., Wang, W. and Wong, M.H. (2011) Mercury Species of Sediment and Fish in Freshwater Fish Ponds around the Pearl River Delta, PR China: Human Health Risk Assessment. Chemosphere, 83, 443-448. http://dx.doi.org/10.1016/j.chemosphere.2010.12.080Souza, V.A. and Wasserman, J.C. (2014) Mercury Distribution in Sediments of a Shallow Tropical Reservoir in Brazil. Geochimica Brasiliensis, 28, 149-160. http://dx.doi.org/10.5327/Z0102-9800201400020004Li, H.B., Yu, S., Li, G.L., Deng, H., Xu, B., Ding, J., Gao, J.B., Hong, Y.W. and Wong, M.H. (2013) Spatial Distribution and Historical Records of Mercury Sedimentation in Urban Lakes under Urbanization Impacts. Science of the Total Environment, 445-446, 117-125. http://dx.doi.org/10.1016/j.scitotenv.2012.12.041Chandra, S., Kulshrestha, M.J. and Singh, R. (2014) Temporal Variation and Concentration Weighted Trajectory Analysis of Lead in PM10 Aerosols at a Site in Central Delhi, India. International Journal of Atmospheric Sciences, 2014, Article ID: 323040.Chaudhari, P.R., Gupta, R., Gajghate, D.G. and Wate, S.R. (2012) Heavy Metal Pollution of Ambient Air in Nagpur City. Environmental Monitoring and Assessment, 184, 2487-2496. http://dx.doi.org/10.1007/s10661-011-2133-4Li, X., Zhang, Y., Tan, M., Liu, J., Bao, L., Zhang, G., Li, Y. and Iida, A. (2009) Atmospheric Lead Pollution in Fine Particulate Matter in Shanghai, China. Journal of Environmental Sciences, 21, 1118-1124. http://dx.doi.org/10.1016/S1001-0742(08)62390-6Melaku, S., Morris, V., Raghavan, D. and Hosten, C. (2008) Seasonal Variation of Heavy Metals in Ambient Air and Precipitation at a Single Site in Washington DC. Environmental Pollution, 155, 88-98. http://dx.doi.org/10.1016/j.envpol.2007.10.038Chiemeka I.U. ,et al. (2010)Air Aerosol Metal Constituent and Concentration at Okigwe, Nigeria International Journal of Physical Sciences 5, 283-286.Li, H.B., Yu, S., Li, G.L., Deng, H. and Luo, X.S. (2011) Contamination and Source Differentiation of Pb in Park Soils along an Urban-Rural Gradient in Shanghai. Environmental Pollution, 159, 3536-3544. http://dx.doi.org/10.1016/j.envpol.2011.08.013Ona, L.F., Alberto, A.M.P., Prudente, J.A. and Sigua, G.C. (2006) Levels of Lead in Urban Soils from Selected Cities in a Central Region of the Philippines. Environmental Science and Pollution Research, 13, 177-183. http://dx.doi.org/10.1065/espr2005.08.275Nabulo, G., Oryem-Origa, H. and Diamond, M. (2006) Assessment of Lead, Cadmium, and Zinc Contamination of Roadside Soils, Surface Films, and Vegetables in Kampala City, Uganda. Environmental Research, 101, 42-52. http://dx.doi.org/10.1016/j.envres.2005.12.016Brown, R.W., Gonzales, C., Hooper, M.J., Bayat, A.C., Fornerette, A.M., McBride, T.J., Longoria, T. and Mielke, H.W. (2008) Soil Lead (Pb) in Residential Transects through Lubbock, Texas: A Preliminary Assessment. Environmental Geochemistry and Health, 30, 541-547. http://dx.doi.org/10.1007/s10653-008-9180-yReeder, P. and Shapiro, L. (2003) Lead Contamination of Soils in Belize City, Belize, Central America. Journal of Environmental Science and Health Part A, 38, 2785-2805. http://dx.doi.org/10.1081/ESE-120025831Duzgoren-Aydin, N.S. (2007) Sources and Characteristics of Lead Pollution in the Urban Environment of Guangzhou. Science of the Total Environment, 385, 182-195. http://dx.doi.org/10.1016/j.scitotenv.2007.06.047Imperato, M., Adamo, P., Naimo, D., Arienzo, M., Stanzione, D. and Violante, P. (2003) Spatial Distribution of Heavy Metals in Urban Soils of Naples City (Italy). Environmental Pollution, 124, 247-256. http://dx.doi.org/10.1016/S0269-7491(02)00478-5Li, H.B., Yu, S., Li, G.L. and Deng, H. (2012) Lead Contamination and Source in Shanghai in the Past Century Using Dated Sediment Cores from Urban Park Lakes. Chemosphere, 88, 1161-1169. http://dx.doi.org/10.1016/j.chemosphere.2012.03.061Stamatis, N., Kamidis, N. and Sylaios, G. (2006) Sediment and Suspended Matter Lead Contamination in the Gulf of Kavala, Greece. Environmental Monitoring and Assessment, 115, 433-449. http://dx.doi.org/10.1007/s10661-006-7238-9Gale, N.L., Adams, C.D., Wixson, B.G., Loftin, K.A. and Huang, Y.W. (2004) Lead, Zinc, Copper, and Cadmium in Fish and Sediments from the Big River and Flat River Creek of Missouri’s Old Lead Belt. Environmental Geochemistry and Health, 26, 37-49. http://dx.doi.org/10.1023/B:EGAH.0000020935.89794.57Christophoridis, A., Stamatis, N. and Orfanidis, S. (2007) Sediment Heavy Metals of a Mediterranean Coastal Lagoon: Agiasma, Nestos Delta, Eastern Macedonia (Greece). Transitional Waters Bulletin, 4, 33-43.Abdel Ghani, S., El Zokm, G., Shobier, A., Othman, T. and Shreadah, M. (2013) Metal Pollution in Surface Sediments of Abu-Qir Bay and Eastern Harbour of Alexandria, Egypt. The Egyptian Journal of Aquatic Research, 39, 1-12. http://dx.doi.org/10.1016/j.ejar.2013.03.001Tan, K.H. (2005) Soil Sampling, Preparation and Analysis. 2nd Edition, CRC Press, Boca Raton.IAEA (2003) Collection and Preparation of Bottom Sediment Samples for Analysis of Radionuclides and Trace Elements. http://www-pub.iaea.org/MTCD/Publications/PDF/te_1360_web.pdfWalkley, A. and Black, I.A. (1934) An Examination of the Degtjareff Method for Determining Soil Organic Matter, and a Proposed Modification of the Chromic Acid Titration Method. Soil Science, 37, 29-38. http://dx.doi.org/10.1097/00010694-193401000-00003EPA (1996) Air Quality Criteria for Particulate Matter, Vol. III, EPA/600/P-95/001cF. http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=2832Rudnick, R.L. and Gao, S. (2003) Composition of the Continental Crust. In: Rudnick, R.L., Holland, H.D. and Turekian, K.K., Eds., Treatise on Geochemistry, Vol. 3, Elsevier-Pergamon, Oxford, 1-64. http://dx.doi.org/10.1016/b0-08-043751-6/03016-4