Emission sources, Characteristics and risk assessment of particulate bound Polycyclic Aromatic Hydrocarbons (PAHs) from trac sites

Atmospheric PM2.5 size particulate-associated Polycyclic Aromatic Hydrocarbons (PAHs) were analyzed from December 2018 to May 2019 over three trac sites of Chota Nagpur Plateau (CNP) of India were analyzed to study their temporal and seasonal variations. Over the last few decades, CNP becomes a hotspot of air pollution due to trac and anthropogenic activities. The PM2.5 concentration was higher than the value given by the National Ambient Air Quality (NAAQ) standard value. The results show the total average concentration of PAHs was found 141.48±22.86, 163.80 ±30.43, and 171.60±26.23 ng/m3 over site (Adityapur) ADP, (Sakchi) SKI, and Mango (MGO), respectively. The PM2.5 total average concentration was found 67.91± 14.04, 79.70± 13.53, and 103.20± 21.77µg/m3 over site ADP, SKI, and MGO, respectively. Diagnostic ratio analysis reveals that the source of PM2.5 associated with PAHs was petrogenic, pyrogenic, coal combustion, and vehicular emission. Backward trajectories model and re count data were also used for air parcel movement up to height 4500 m above the earth’s surface. The trac campaign has provided a rare opportunity for the CNP region for the collection of more air pollution baseline data, which could be helpful in the formulation of air pollution reduction policies in the future


Introduction
Last few decades, air pollution becomes a major problem on the global platform. Particulate matter size less than 2.5 µm (PM 2.5 ) linked Polycyclic Aromatic Hydrocarbons (PAHs) becomes an excessive danger to human health as a consequence of its teratogenic, mutagenic, and carcinogenic properties (Kumar et al., 2020a). Due to the smaller particulate size, it cannot be trapped by the upper part of the respiratory tract and can penetrate the lungs (Thomas, 2013). Particulate having great adsorbing ability by providing a large surface area, where various toxic substances can deposit, including PAHs (Jermann et al., 1989).
PAHs are persistent carbon-based combinations poised of two or additional aromatic rings fused (Yang et al., 2010; International Agency for Research on Cancer (IARC), 1984(IARC), , 1983Boeuf et al., 2016;Kumar et al., 2020a). Based on molecular weight, PAHs categories into two classes, Low molecular weight PAHs including two-three rings fused, exist in the vaporous stage, and high molecular weight PAHs, including over four aromatic rings, occur in the particulate stage (Chrysikou and Samara 2009;Baek et al., 1991). In emerging countries like India, It is essential to identify air pollution due to tra c emissions. High highway tra c ow is one of the most signi cant homes of particulate-associated PAHs emission (Yin et al., 2010). The particulate bound PAHs in tra c emission source including, diesel and gasoline exhaust, fuel evaporation, brake pads wear and disc brake, spillage of fuel and lube oil, drains and road outward materials, re-suspension of highway dust, separating, abridgment (Lawrence et al., 2013; particulate-bound PAH emissions in the urban atmosphere (Jang et al., 2013). Apart from these coals, wood, and biomass burning, industrial emission, like anthropogenic activities, are also responsible for particulate-bound PAHs in the tra c zone (Zhang et al., 2008). Long-distance transport is also accountable for particulate-bound PAHs in the tra c zone (Ravindra et al., 2008). Anthropogenic activities are responsible for particulate emission. Biological activities, including forest re and volcanic eruption, are also accountable for particulate-bound PAHs in the atmosphere (Kumar et al., 2020a;Xu et al., 2006;Baek et al., 1991).
Jamshedpur is an economic megacity in the Chota Nagpur Plateau (CNP) region provoked by heavy air e uence (Kumar et al., 2020b). The present study, identify of PAH were conducted from December 2018 to May 2019. The samples were collected by mini volume sampler to assess PM2.5 bound PAH concentrations temporal deviations and understand probable source ranges of PAH using diagnostic ratio (DR) models. Furthermore, we also consider the spatial and periodic features of PM2.5 associated PAHs. These study potential implications will be to make a more robust air quality management plan of the city and recognize source-speci c effects of particulate matter on human health. The key objective was to expand better empathetic compound characteristics, seasonal disparity, probable causes, and human health hazard calculation due to particulate bound PAHs at Jamshedpur city tra c area.

Study area
Measurements of PM2.5 bound PAHs have been performed over three sites Adityapur (ADP), Mango (MGO), and Sakchi (SKI). The site selection was made in such a way that to cover the overall scenario and the small-vehicle, signi cant vehicle movement during the study area ( Figure 1). The tra c site is located in Jamshedpur city, the central region of CNP India longitude and latitude (22 0 80' N and 86 0 20' E). This town is bordered by luxurious green Dalma peaks covering 209 km 2 at the Chota Nagpur Plateau (CNP). There are tropical dry and wet weather and climate over this study area. Conferring to the registration of 2011, Jamshedpur whole habitat is about 1.3 million, with 6400 persons per km 2 density of populace (Census 2011). Total 8 33,983 registered vehicles are running in Jamshedpur, East Singhbhum district of Jharkhand state of India (https://vahan.parivahan.gov.in). Jamshedpur is one of the decent organized and biggest industrial Cities of CNP. More than one thousand industries are running under the Adityapur Industrial Development Authority (AIDA). Due to many industries such as chemical plants, paint industry, steel industry, plastic industry, etc., emission of large amounts of air pollutants. The transportation of goods and industrial products to other states leads to a high load on Jamshedpur tra c. Tra c emission is also responsible for the PAHs emission in the environment.

Sampling procedure
The ambient PM 2.5 sample monitoring was performed from selected locations in CNP on the seasonal event. A total of 48 samples were collected throughout the winter and summer from December 2018-May 2019. The sampling was done by a mini volume sampler (Envirotech Model type APM 550) functioning at a ow rate of 16.5 L/m 3 . During the campaign 47 mm PTFE lter (Merck, Catalog no-PM2547050) was used to accumulate particulate-phase PAHs. Pre-digested lters were weighed thrice to get accurate weight before sampling. Loaded lter with particulate matter are also weighed thrice after sampling to decide the exact mass of the particulate by a lone pan-top packing numerical weight machine (VWR, Model no: VWR1611-2263: with Weighing chamber L×W×H: 162×171×225 mm). Background impurity was checked by expending functioning blanks (unexposed lters) treated concurrently with eld samples. Furthermore, the lter is kept in aluminum foil and packed well, and preserved in a culture box. Before the investigation, these samples were retained in a fridge at under 4 0 C for conservation.

Sample analysis
Analysis of lter containing PM 2.5 associated 16 USEPA Priority PAHs including Napthelene (NAP), Acenaphthylene (Acy), Chrysene (Chr), Benzo Chrysene-D12 (CAS Number -1719-03-5). After that, the extracted solution volume was reduced by the rotatory evaporator. The extracts were puri ed using sodium sulfate -silica gel column (glass column of 30cm long and 3cm diameter). The target solutions were eluted with 10 ml dichloromethane (DCM) and hexane solvent (1:1v/v). The further puri ed excerpt was reduced up to 1-2 ml by again rotatory evaporator. The PAHs were recognized by the Gas Chromatography attached by the Flame Ionization Detector (GC-FID, Agilent-7890B) furnished with capillary pillar HP-5MS (30 m × 0.32 mm × 0.25 µm) with a seven-inch cage. In a split less manner, 1 µl of every sample was inserted. Nitrogen gas was used as a transferor gas with a ow rate of 2 ml min -1 . The oven temperature was initiated at 60 0 C for 3 min and improved up to 320 0 C at the rate of 5 0 C min -1 and hold for 20 min. The peak area of individual bands and retention factor, the 16 USEPA signi cance PAHs concentrations were quanti ed. Recoveries of PAH complexes were above 75%. The laboratory eld test and blanks blank test has performed for samples were revealed and examined in the identical technique as eld test sample investigation, and the PAH compound was not perceived in blank samples. The sample and blank solutions were then transferred into 50 mL vials, labeled, and stored in the refrigerator before analysis.

Quality control
The deuterated labeled PAHs; Pyrene-D10, Anthracene-D10, Phenanthrene-D10, Naphthalene-D8, and Chrysene-D12 were used for the recovery studies, and the recoveries were 98 ± 13%, 82 ± 14%, 92 ± 13%, 38 ± 12%, and 103 ± 12%, respectively. The method detection limits (MDLs) were examined using the laboratory blanks and 8 eld blanks spiked with the known number of targeted PAHs standards. The MDLs were calculated as the mean concentration of target compounds in eld blanks in addition to the blanks standard deviance three times. The limit of quanti cations (LOQs) was designed as ten times the standard deviation. Field blank analysis was used to eliminate the error during the sampling campaign.
The LOD and LOQ value was in the array of 0.01-0.05 and 0.04-0.20 µg/l correspondingly. The concentration was less than the detection limit considered as (<DL).

Results And Discussion
3.1 Spatial-temporal variations of PM 5 associated PAHs The detail of the seasonal concentration of PAHs and PM 2.5 given in Table 1 Calculated PM 2.5 linked PAHs in the winter season was found more remarkable than other seasons because of the primary source of emission, such as domestic cooking or heating emission, vehicular emission, etc. Additionally, the concentration was high because of the reduction of atmospheric dispersion of particulate and PAHs concentration sorption on particulate bound PAHs due to a decrease in air temperature (Ravindra et al., 2008). Furthermore, particulate-bound PAH concentration is generally found less in the warm period because of less emission from primary sources. Metrological conditions like higher temperature and wind allow them to dispersion with higher mixing height, favoring the pollutant in gas phase portioning and photodegradation of PM 2.5 associated PAHs. A similar seasonal variation has been designated in earlier work (Chrysikou and Samara, 2009;Gianelle et al., 2013).

Diagnostic Ratio Analysis
Diagnostic ratios of PAHs were used to deliver reliable evidence on PAH's emission cause in the atmosphere. The ratio of Ant/(Ant+Phe), Flua/(Flua+Pyr), Flua/Pyr, Phen/Ant IcP/(IcP+B(ghi)P), and BaP/B(ghi)P were used to determine the seasonal cause of emission of particulate linked PAHs. The value of Ant/(Ant+Phe) ratio is less than 0.1 directed petrogenic source and signi cance upper than the 0.1 indicated pyrogenic source over all the three tra c sites (Pies et al., 2008). The ratio of Flua/(Flua+Pyr) less than 0.1 directed petrogenic/ unburned petroleum source, the value found between 0.4-0.5, the source is fossil fuel burning if value found higher than 0.5 the source identi ed as coal & biomass burning (Yunker et al., 2002;De La Torre-Roche et al., 2009). The ratio of Flua/Pyr less than 0.1 directed, petrogenic cause, and larger than 1 indicated fossil fuel combustion cause (Sicre et al., 1987). The ratio of Phen/ Ant less than 10 indicated the pyrogenic source, and higher than 10 directed coal combustion was the predominant source. The ratio of BaP/B(ghi)P and IcP/(Icp+B(ghi)P) was an indicator for tra c and non -tra c emission sources of PAHs over all the site (Hussain et al. 2015). The PAHs ratio over three tra c sites ADP, SKI, and MGO, plotted in Figure 4, indicating the petrogenic, Pyrogenic, coal burning, and vehicular discharge was the chief source of emission of PAHs over the study site in both cold and warm seasons of CNP.

Backward Trajectories
The backward trajectories model was used for improved perception of contamination affected by air particulates transported by air or discharged by the resident basis causes. Proportions of height coordinates with respect 7-day isentropic back trajectory was investigated for full run time 168 h up to altitude level of 500 m with Meteorological Data Explorer (METEX, http://db.cger.nies.go.jp/metex/trajectory.html) in winter and summer season as shown in Figure 5. At various heights up to 4500 m beyond the ground, back trajectory analysis has been examined to elucidate aerosol possessions changeability linked with airborne particulate matter in the whole atmospheric outline on a seasonal basis. Winter season trajectories show that most of the Indo-Gangetic plain (IGP) mass is from the central Asia region. Summer season trajectories show that the aerosol mass loading form mainly originated from CNP. Some assembly was loaded from the Bengal region, south and south-Eastern part of the country.
Fire counts data were also incorporated in the backward trajectory model by the Moderate Resolution Imaging Spectroradiometer (MODIS) from the National Aeronautics and Space Administration (NASA) satellite was used to assess dynamic combustion over India during the study period. The uni ed re count data are accessible at https://earthdata.nasa.gov/earth-observation-data/near-real-time/ rms.

Health Risk Assessment
The adverse effect of the introduction of particulate-linked PAHs on human health is calculated by the equivalent toxicity concentration (TEQ) equation (Yu et al., 2008;Yang et al., 2007). TEQ expression represents the sum of assessed carcinogenic risk quali ed to BaP for entirely PAHs having carcinogenic potential, which can be assessed by multiplying the concentration of every PAHs carcinogenic and toxicity equivalence factor (TEF) value given by Nisbet and Lagoy (1992) (Peng et al., 2011;USEPA., 1991;Chen and Liao., 2006). ILCR was considered by assessing the corresponding lifetime average daily dose (LADD) of PAHs by allowing in two age group, children (age 6 years) and adult (age 70 years), having Inhalation rate (IR) air inhalation rate of 10 m 3 /day for children and 20 m 3 /day for an adult (Soltani et al., 2015). The Exposure frequencies (EF) were considered 365 days/year for both children and adults (Kumar et al., 2013). Bodyweight of child and adult were considered 18 kg for child and 60 kg for adults (ICMR., 2009), and the averaging time (AT) for hazards was 70 years. Exposure duration was considered as 24 years (USEPA., 2011). The following equation was used to calculate LADD and ILCR.

ILCR = LADD × CSF (Cancer Oral Slope Factor)
Cs is the quantity of PAHs renewed concentration grounded on TEQ assessment in airborne particulate (ng/m 3 ). In the present study, CSF symbolizes the inhalation cancer slope factor (3.85 mg kg -1 day -1 ) (Peng et al., 2011). The LADD value and ILCR value were calculated, and the values of the details are presented in Table 3. Auxiliary, the Excess Life Time Cancer Risk (ELCR) was assessed by the sum of ILCR for Adult and ILCR value for the child overall study site. The ELCR value over ADP, SKI, and MGO sites was found 13.89 × 10 -6 , 16.17 × 10 -6, and 16.49 ×10 -6 respectively. The ELCR value lies in the tolerable limit 10-6-10-4 given by USEPA (USEPA. 1989). The outcome presented that the risk level was tolerable over ADP, SKI, and MGO tra c sites.

Conclusion
In the present study, PM 2.5 associated PAHs were examined in three CNP tra c sites in the cold and warm seasons. The total average concentration of PAHs was found 141.48±22.86, 163.80 ±30.43, and 171.60±26.23 ng/m 3 over area ADP, SKI, and MGO, respectively. The PM 2.5 total average concentration was found 67.91± 14.04, 79.70± 13.53, and 103.20± 21.77µg/m 3 over site ADP, SKI, and MGO, respectively. The concentration of PM 2.5 was found upper than the NAAQ standards value of 40 µg/m 3 over the three study sites in together (cold and warm) season. The concentration of PM 2.5 linked PAHs was found upper in the cold season than the warm season. Diagnostic ratio analysis reveals that the source of PM 2.5 allied PAHs was petrogenic, pyrogenic, coal combustion, and vehicular emission was the principal cause of emission of PAHs. Backward trajectories model and re count data were also used for air parcel movement up to height 4500 m above the earth's surface. The health threat due to the introduction of PM 2.5 linked PAHs was analyzed. BaP and DBahA were the highest contributors to carcinogenicity. BaP contributes 35.72, 38.11, and 39.54 % carcinogenicity over the PAHs samples tra c site, respectively. DBahA contributed 50.52, 47.82, and 45.25 % carcinogenicity over ADP, SKI, and MGO sites, respectively. LADD and ILCR value was also calculated for all the study site. The ELCR value over ADP, SKI, and MGO site was found 13.89 × 10 -6 , 16.17 × 10 -6, and 16.49 × 10 -6, respectively. The obtained data represent an exclusive contribution to the complex assessment of human exposure to PAHs in tra c sites, with the background of mid and heavy tra c zones. Figure 1 Three tra c sampling site of Adityapur (ADP), Sakchi (SKI), and Manno (MGO) area of East India. Note: The designations employed and the presentation of the material on this map do not imply the expression of any opinion whatsoever on the part of Research Square concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. This map has been provided by the authors.