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PAHs in India | Polycyclic Aromatic Hydrocarbon | Factor Analysis

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ARTICLE IN PRESS Chemosphere xxx (2006) xxx–xxx www.elsevier.com/locate/chemosphere Polycyclic aromatic hydrocarbons (PAHs) concentrations and related carcinogenic potencies in soil at a semi-arid region of India Amit Masih, Ajay Taneja * School of Chemical Sciences, Department of Chemistry, St. Johns College, Agra, Uttar Pradesh 282 002, India Received 10 August 2005; received in revised form 7 December 2005; accepted 25 January 2006 Abstract A study of polycyclic aromatic hydrocarbons in su
  Polycyclic aromatic hydrocarbons (PAHs) concentrations andrelated carcinogenic potencies in soil at a semi-arid region of India Amit Masih, Ajay Taneja * School of Chemical Sciences, Department of Chemistry, St. Johns College, Agra, Uttar Pradesh 282 002, India Received 10 August 2005; received in revised form 7 December 2005; accepted 25 January 2006 Abstract A study of polycyclic aromatic hydrocarbons in surface soil was conducted at selected locations in Agra (semi-arid region of India) fora span of one year in order to ascertain the contamination levels. The concentrations of PAH were measured at four locations in the cityof Agra, which covers industrial, residential, roadside and agricultural areas. The samples were extracted with hexane by ultrasonic agi-tation. The extracts were then fractioned on a silica-gel column and the aromatic fraction was subjected to HPLC. The average concen-tration of total PAH in all samples was 12.1 l g g À 1 and the range was from 3.1 l g g À 1 to 28.5 l g g À 1 . The maximum concentrations of PAHs were found to be in winter season. The concentration of PAH decreased in the order chrysene > benzo( b )fluoranthene > fluoranth-ene. Factor analysis suggests that the mixed signature of all the sources are intermediate between vehicular and combustion activities. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: HPLC; Polycyclic aromatic hydrocarbon; Semi-arid region; Surface soil 1. Introduction Polycyclic aromatic hydrocarbons (PAHs) are chemicalscontaining two or more fused benzene rings in a linear,angular or cluster arrangement. PAH contain only carbonand hydrogen. They are usually generated under inefficientcombustion conditions, such as insufficient oxygen (Soren-sen, 1994; Nam et al., 2003) by primary natural sourceswhich are forest fires and volcanic activity, but most of the PAHs released into the environment arise from anthro-pogenic sources such as burning of fossil fuels, petroleumrefinery, industrial processes, as a constituent of coal tarand motor vehicle exhaust. The lighter PAH (2–3 rings),which are generally not carcinogenic, are mostly found inthe gas phase while the heavier ones are mainly associatedwith airborne particles. Heavier PAH (with more thanthree rings) are rapidly attached to existing particles, usu-ally soot particles, by adsorption or condensation uponcooling of fuel gas (Kamens et al., 1995). The environmen-tal occurrence of PAHs has been associated with adverseeffects on public health (Grimmer et al., 1983; Yanget al., 1991; Rost and Loibner, 2002). Persistent organicpollutants (POPs) are transported in the atmosphere atover short and long distances in both gaseous and particu-late forms. Although some POPs are released slowly intothe atmosphere (Harner et al., 1995), these omnipresentcompounds are subject to redistribution and transforma-tion processes (Reilley et al., 1996; Massei and Ollivon,2004). Atmospheric deposition constitutes the main inputof semi-volatile organic compounds to soil (Tremoladaet al., 1996). Once entered in the soil they accumulate inhorizons rich in organic matter where they are likely tobe retained for many years due to their persistence andhydrophobicity (Krauss et al., 2000). Consequently, soilsare an important reservoir for these compounds (Ockendenet al., 2003) and exchanges between soils and the atmo-sphere is a widely studied process (Bidleman and McCon-nell, 1995; Wania and Mackay, 1996). With the increase 0045-6535/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.doi:10.1016/j.chemosphere.2006.01.062 * Corresponding author. Tel.: +91 562 2800882. E-mail address: ataneja5@hotmail.com(A. Taneja). www.elsevier.com/locate/chemosphere Chemosphere xxx (2006) xxx–xxx ARTICLE IN PRESS  in fossil fuel combustion, resulting from the industrialexpansion, traffic and population growth, over last few dec-ades, the atmospheric concentrations of PAH in Asiancountries are expected to be high. Thus it is important toacquire information about this environmental compart-ment and its role in micro pollutant cycle.In India, few studies have reported ambient PAH con-centration in Ahmedabad (Raiyani and Shah, 1993), Mum-bai (Sahu et al., 2001), Delhi (Kannan and Kapoor, 2004). To our knowledge there has been a shortage of soil PAHstudies. Since PAHs are one of the most serious pollutantsbecause of their carcinogenicity and mutagenicity (IARC,1983; Yang et al., 1991; Massei and Ollivon, 2004) whichhave drawn attention of the scientific community, it isimportant to determine the amounts of PAHs in soil astheir concentration in soil correlates significantly with thecorresponding levels in air (Vogt et al., 1987; Nam et al.,2003; Massei and Ollivon, 2004) and is a good indicatorof the surrounding air pollution and the proximity of sources. The aim of this study was to determine soil con-tamination by PAHs and to identify sources based on vari-ations in PAHs profiles between the sites as well as to assessthe carcinogenic potencies related to PAHs. 2. Materials and methods  2.1. Regional site description Agra, the city of Taj Mahal (27 ° 10 0 N 78 ° 02 0 E) is locatedin the north central part of India about 200 kms South of Delhi in the Indian state of Uttar Pradesh. Agra is consid-ered as a semi-arid zone as two third of its boundary aresurrounded by the Thar desert of Rajasthan. Three high-ways are crossing the city. The climate during summer ishot and dry with temperature ranging from 32 ° C to48 ° C. In winter the temperature ranges from 5.5 ° C to30.5 ° C. The down ward wind is south–south-east i.e.SSE 29% and north-east i.e. NE 6% in summers and it iswest–north-west i.e. WNW 9.4% and north–north-westi.e. NNW 11.8% in winters. The atmospheric pollutionload is high because of the down ward wind; pollutantsmay be transported to the different areas mainly from anoil refinery situated in Mathura (50 kms from the centerof Agra City). Agra has 1271000 of population. 386635vehicles are registered and 32030 generator sets are used.It has been indicated earlier that in Agra, 60% pollutionis due to vehicles (CPCB,Amar Ujala, 2005). St. John’sCollege, which is situated in the heart of Agra city, is con-sidered as a roadside area. It lies by the side of a road thatcarries a maximum traffic density of about 10 5 vehicles perday, which results in production of smoke, and total sus-pended particulate matter by engine idling and gearchanges. Nunhai has being considered as an industrial zonebecause large number of diesel generator sets plants, ironprocessing and tanning industries are there. Towards thenorth is located Dayalbagh which is exclusively agricul-tural area. The Taj trapezium (area surrounding the TajMahal 10400 $ km 2 ) located to the south of the site is con-sidered to be a residential area, which is totally a green belt.  2.2. Sample collection For the purpose of sample collection Agra city wasdivided into four parts based on industrial, roadside, agri-cultural and residential locations. Samples were collectedwith the help of an auger from 0 to 6 cm of topsoil. A totalof 319 soil samples were collected (80 from each location)for analysis. The collected samples were sieved through20-mesh sieve and stored in polybags in a refrigerator.  2.3. Extraction and analysis of PAHs Twenty gram of soil sample was extracted for 45 minwith hexane (30 ml) in an ultrasonic bath extractor. Theextract was decanted at the rate of 3300 rpm in a decanter( Supelco ) and then passed through silica-gel column for thepurification (EPA, 1994). The obtained extract was evapo-rated by a flow of nitrogen and redissolved in 1 ml of Ace-tonitrile. The extract was analysed for PAH’s by using theHPLC with UV visible detector ( Shimadzu LC-10AD ). Theanalytical column was of 250 mm length and 4.6 mm i.d;packed with totally porous spherical RP-18 material (Par-ticle size 5 l m) preceded by a guard column (10 mm longand 4.6 mm i.d.). Acetonitrile–water mixture (70:30) wasused as mobile phase at a flow rate of 1.5 ml min À 1 . Sam-ples of 100 l l (0.1 ml) were injected into the columnthrough the sample loop. For the detection of compoundsUV detector was set at 254 nm for analysis. The data wasprocessed with a CR7A chromatopac data processor.Standards were obtained individually (as the solids) frompolyscience Chemical Company, USA. The followingcompounds were quantified: naphthalene, acenaphthene,acenaphthylene, fluorene, phenanthrene, anthracene, fluo-ranthene, pyrene, benzo( a )anthracene, chrysene, benzo( b )fluoranthene, benzo( k  )fluoranthene benzo( a )pyrene andbenzo(  ghi  )perylene. All these compounds are on theUSEPA priority pollutants list. The procedure describedabove has been checked for recovery efficiencies usingspiked PAH standards. Recoveries range between 30%and 70%, with the lower values corresponds to the lowermolecular weight PAH compounds. Presented data are cor-rected accordingly with the means of triplicate analyses.Replicated analyses give an error between ±10% and±20% for PAH in soils. 3. Results and discussion 3.1. PAHs in soil particles The average and standard deviation of individual PAHconcentrations measured insoils atthevarious sitesarepre-sented inTable 1. The total PAH (t-PAH) concentrationswere 13.72, 12.98, 9.37 and 6.73 l g g À 1 at industrial, road-side, residential and agricultural sites respectively. The 2 A. Masih, A. Taneja / Chemosphere xxx (2006) xxx–xxx ARTICLE IN PRESS  mean concentration of t-PAH was 12.14 l g g À 1 for all sitestogether. The industrial sites had the highest total PAHconcentration followed by roadside, residential and agricul-tural site. High concentrations at industrial site can be duetothe location ofthe site, which is well knownfor generatormanufacturing, tanning and iron casting industries. Con-centrations at roadside may result from the proximity of the busy road, which has very intense automobile trafficabout 10 5 vehicles per day.Trapido (1999)estimatedPAH content at agricultural site about 0.10 l g g À 1 whichwas considered as background value for PAH. Observedvalue(6.70 l g g À 1 )ofPAHatagriculturalsiteishigherthanthe background levels may be due to the atmospheric trans-port ofPAH fromsourcestoremote sites. These results alsoindicate that PAH concentration are strongly linked to theland use of the site. The trends of the concentrations of themajor PAH found in present study were chrysene > fluo-ranthene > benzo( b )fluoranthene at industrial site, chry-sene > benzo( b )fluoranthene > fluoranthene at roadsideand chrysene > benzo( b )fluoranthene > naphthalene at res-idential and agricultural sites. In all the sites chrysene andbenzo( b )fluoranthene were the predominant compounds.This might be due to industrial-oil burning, wood combus-tion and emission coming from diesel powered vehicles(Ravindra et al., 2001).Table 2shows a worldwide comparison of PAH concen-tration with the present study. The PAH concentration insoil of industrial (13.72 l g g À 1 ) and roadside (12.98 l g g À 1 )areaofAgraislessthantheconcentrationfoundinAustria/Germany (79.00/16.00 l g g À 1 ) and USA (58.60 l g g À 1 ),respectively, whereas residential (9.37 l g g À 1 ) and agricul-tural (6.73 l g g À 1 ) sites concentrations of PAH were foundto be higher than in UK (4.20 l g g À 1 ) and Germany(1.90 l g g À 1 ), respectively. As evident from theTable 2theconcentrations measured insoils ofvarious sitesatAgra(industrial, roadside, residential and agricultural) showmuch difference between each other. In the present data,contamination in the urban industrial area appears to betwo times higher than in agricultural areas; similar resultshave been reported in earlier studies (Tremolada et al.,1996; Wagrowski and Hites, 1997).Fig. 1shows the relative contribution of 2-, 3-, 4-, 5-,and 6-ring PAHs in the soils of different locations investi-gated in this study. The average percentage of t-PAH basedon the rings were 9.15% (2 ring), 23.1% (3 ring), 47% (4ring), 13.4% (5 ring), and 7.15% (6 ring). TheFig. 1alsoillustrates that 4-ring and 3-ring PAHs were found to be Table 1Mean concentration with SD of PAHs at different locations of Agra ( l g g À 1 )PAHs Industrial Roadside Residential AgriculturalMean ± SD Mean ± SD Mean ± SD Mean ± SDNAP 1.18 ± 1.11 1.07 ± 1.84 0.90 ± 1.16 0.69 ± 0.77ACY 0.62 ± 0.54 0.47 ± 0.62 0.33 ± 0.57 0.42 ± 0.61ACE + FLU 1.06 ± 1.72 0.97 ± 1.88 0.82 ± 1.20 0.63 ± 0.60PHE 0.43 ± 0.51 0.32 ± 0.37 0.47 ± 0.66 0.14 ± 0.31ANT 1.29 ± 1.12 1.02 ± 0.66 0.57 ± 0.39 0.36 ± 0.21FLT 1.72 ± 1.02 1.29 ± 1.17 0.89 ± 1.11 0.58 ± 0.32PYR ND 1.23 ± 1.41 ND NDB( a )A 0.81 ± 1.06 0.56 ± 0.45 0.45 ± 0.31 0.26 ± 0.21CHR 4.07 ± 2.26 3.19 ± 2.36 3.03 ± 2.91 2.19 ± 2.18B( b )F 1.53 ± 1.47 1.32 ± 1.20 1.27 ± 1.41 0.92 ± 1.42B( k  )F ND 0.30 ± 0.83 ND NDB( a )P ND 0.39 ± 0.36 ND NDB(  ghi  )P 1.01 ± 1.09 0.85 ± 0.72 0.64 ± 0.79 0.54 ± 0.43Total 13.72 ± 11.90 12.98 ± 13.87 9.37 ± 10.46 6.73 ± 7.12NAP—Naphthalene, ACY—Acenapthylene, ACE—Acenapthene, FLU—Fluorene, PHE—Phenanthrene, ANT—Anthracene, FLT—Fluoranthene,PYR—pyrene, B( a )A—Benzo( a )fluoranthene, CHY—Chrysene, B( b )F—Benzo( b )fluoranthene, B( k  )F—Benzo( k  )fluoranthene, B( a )P—Benzo( a )pyrene,B(  ghi  )P—Benzo(  ghi  )perylene.Table 2Soil PAH concentrations compiled from literature dataStudy area PAHconcentration( l g g À 1 )Numberof PAHReference Agricultural (rural) Brazil 0.096 20Wilcke et al. (1999a)UK 0.19 12Wild and Jones (1995)Germany 1.90 06Tebaay et al. (1993)India 6.7 11 Present study Residential (urban) Bangkok 0.38 20Wilcke and Muller (1999b)Brazil 0.39 20Wilcke et al. (1999a)Germany 1.80 06Tebaay et al. (1993)UK 4.20 12Wild and Jones (1995)India 9.3 11 Present study Roadside (urban) Australia 3.30 14Yang et al. (1991)USA 58.68 14Rogge et al. (1993)India 12.9 14 Present study Industrial (urban) UK 4.50 12Wild and Jones (1995)Germany 16.00 06Tebaay et al. (1993)Austria 79.00 18Weiss et al. (1994)India 13.7 11 Present study A. Masih, A. Taneja / Chemosphere xxx (2006) xxx–xxx 3 ARTICLE IN PRESS  dominant in the soils of Agra region having 47% and 23.1%of the t-PAH whereas 5-ring compounds including ben-zo( a )pyrene (considered to be most carcinogenic com-pound) contributes only 13.4% of the t-PAH. 3.2. Seasonal variation The climate of Agra can be broadly classified into threeseasons, winter (November–February), summer (March– June) and monsoon (July–October).Table 4summarizesthe seasonally averaged concentrations of all measuredPAH in soil at four sites of Agra; i.e. industrial, roadside,residential and agricultural. The concentrations of PAHin winter, summer and monsoon are dominating in indus-trial area i.e. 20.45, 13.43 and 7.28 l g g À 1 , respectively,whereas the lowest concentrations of PAH are formed tobe in agricultural area i.e. 10.18, 6.21 and 3.80 l g g À 1 ,respectively. The concentrations of PAH in roadside as wellas residential sites were found to be 17.07 and 13.04 l g g À 1 in winter, 12.12 and 9.25 l g g À 1 in summer and 9.75 and5.82 l g g À 1 in monsoon. The differences in PAH concentra-tion in soil is due to the characteristics of individual sites.Although the trend of seasonal variation of all PAH atall the sites is similar in nature i.e. maximum concentrationof PAH were found to be in winter followed by summerand monsoon seasons. This trend can be easily visualizedinFig. 2. Differences in concentration of PAH in soil canbe explained with the different meteorological conditionsof these seasons. Temperature of soil is a very importantfactor in determining the leachability or mobility of soilPAH. In this region, summer is generally characterizedby high temperature ranging from 35 ° C to 47 ° C. Theleaching concentration of PAH at present site increaseswith increasing temperature as biodegradation and volatil-ity accompanied by rising temperature (Kim and Osako,2003), resulting the lower PAH in the summer than in win-ter season. In contrast, in the winter season at low temper-ature microbial breakdown of PAH is decreased resultingthe higher concentration of PAH at this season. While dur-ing the months of monsoon season the region is generallyexperienced with the frequent rain showers and washouteffects of pollutants. In addition to dry deposition, wetdeposition (rain) of PAH may also occur at soil surfacein this season and should have resulted in higher soilPAH concentration. In contrast, the concentration of soilPAH was observed to be lower in monsoon. Lower concen-tration of PAH during the monsoon season in this regioncan be explained due to the percolation of PAH into theinner depth of the soil. Although, percolation of PAHdepends on several factors like PAH molecular structure,water solubility, Henry’s constant, mode of transport andflow rate. The total PAH ratios of winter and Monsoon(W/M) seasons varied from 1.8 to 2.8 with the maximum(W/M) ratios observed for industrial followed by agricul-ture, residential and roadside. Lower (W/M) ratios of PAH at roadside soil may be due to the high vehicularemissions and the continuous deposition of PAH on road-side at all seasons. 3.3. Factor analysis A varimax rotated factor analysis was performed toidentify the main sources influencing the PAH concentra-tion at the sampling sites. In this statistical method a setof multiple inter correlated variables is replaced by smallnumber of independent variables (factors) by orthogonaltransformations (rotations). This is achieved by diagnosingthe correlation matrix of the variable i.e. by computingtheir Eigen values and Eigen vectors. Factor loadingsobtained after the rotation called varimax rotation givesthe correlation between the variables and the factors. Eachvariable was also evaluated for its KMO value (KeiserMayer Olvin), which gives sampling adequacy, and datawas included in the matrix only if it had Eigen valuesgreater than one. The varimax procedure was adoptedfor rotation of the factor matrix to transfer the initialmatrix into one that was easier to interpret. In the present Table 3Mean, range and TEFs of PAHs with BAP exposure at Agra ( l g g À 1 )PAHs Mean Range TEFs a BAP exposure NAP 0.96 0.27–2.06 0.001 0.00096ACY 0.46 0.09–1.56 0.001 0.00046ACE + FLU 0.87 0.10–1.90 0.001 0.00087PHE 0.34 0.06–0.96 0.001 0.00034ANT 0.81 0.10–1.88 0.01 0.0081FLT 1.12 0.38–2.98 0.001 0.00112PYR 1.23 0.49–3.07 0.001 0.00123B( a )A 0.52 0.12–1.61 0.1 0.052CHR 3.12 0.99–6.44 0.01 0.0312B( b )F 1.26 0.34–2.64 0.1 0.126B( k  )F 0.30 0.04–0.71 0.1 0.030B( a )P 0.39 0.07–0.94 1 0.39B(  ghi  )P 0.76 0.14–1.79 0.01 0.0076Total 12.14 3.19–28.54 1.33 0.65 a TEFs compiled byTsai and Shih (2004).Fig. 1. Distribution of PAHs in the soil of different locations of Agra.4 A. Masih, A. Taneja / Chemosphere xxx (2006) xxx–xxx ARTICLE IN PRESS
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