Lead Levels in the Airborne Dust Particulates of an Urban City of Central India

LEAD LEVELS IN THE AIRBORNE DUST PARTICULATES OF ANURBAN CITY OF CENTRAL INDIA

MANISHA THAKUR and MANAS KANTI DEB∗School of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur-492 010, M.P. India

(∗ author for correspondence, e-mail: [email protected])

(Received 18 August 1998; accepted 26 April 1999)

Abstract. The dust fall-out rate, distribution pattern and concentration of lead in the particulatefall-out matters in urban Raipur city covering an area of 160 km2 during one hydrological yeari.e. November 1996–June 1997, has been described. The entire city has been divided into 6 zonescomprising of industrial, commercial, residential and heavy traffic areas. A monthly collection andanalysis of dust fall-out rate between 3.0(±0.1) and 91.3(±1.2) metric tonnes km−2 month−1 wereobserved at all 6 sampling sites. The total annual flux of lead in the fall-out of the city at differentzones is in the range 0.0065–0.4304 kg km−2 yr−1. The results show that dust fall-out and the leadlevels both are at higher magnitudes in winter and autumn. These large levels of air pollutants havealso been correlated with some meteorological parameters like relative humidity and temperature,and strong positive correlations have been observed.

Keywords: airborne dust particulates, distribution pattern, fall-out analysis, flux, lead

1. Introduction

The occurrence of lead in the dust fall of the urban atmosphere is considerablyincreased as a result of the use of tetraethyl lead as antiknock agent in the com-bustion of vehicular fuel and through industrial processes, such as lead and nonferrous metal, smelters, incineration and combustion of residential fuels (Nriageeand Davidson, 1986; Gilliet al., 1988). However, in Europe and in some other partsof the world, lead is mostly replaced by other antiknock agents.

Lead is a well documented metal toxicant, exposure of which leads to manyfatal diseases, including the dysfunction of renal blood and neurological systems(Mittal, 1995). Lead enters the body through the lungs and accumulates in bonesand various tissues. However, the amount of lead which enters by the food chain,via soil, vegetation, and water via percolation of soluble lead into ground water,are more important for the health-risk point of view (Daviset al., 1997).

Airborne particulates have become one of the major threats to living beings andtherefore, several studies are reported from all parts of the world on many differentaspects of airborne metal pollutants (Migonet al., 1991; Duceet al., 1982; Baeyenset al., 1990). Many of these studies are based on the sampling and analysis in thevicinity of dust emitting sources (Müezzinogluet al., 1990, 1994). High heavymetal contamination around the Aliaga industrial site in Turkey, especially near

Environmental Monitoring and Assessment62: 305–316, 2000.© 2000Kluwer Academic Publishers. Printed in the Netherlands.

306 M. THAKUR AND M. KANTI DEB

the iron smelters and steel mills, have been reported to be due to heavy industrialactivities (Bayramet al., 1997). Seth and Pandey (1983) have reported the dust fall-out rate and lead content, in the vicinity of a steel plant, in the range 60.4–836.2metric tonnes km−2 month−1 and 119.3–301.6 mg kg−1, respectively. Investiga-tions on metal concentrations, in particulate matter in the ambient air of a steel city,Rourkela in eastern India, have shown the existence of tremendous contaminationin air (Tiwari and Chowdhury, 1993). The possible cause of lead contamination inthe airborne particulates of urban Valencia city in Spain have reported car traffic asa main source and sulphur dioxide as subsidiary source (Mañeset al., 1991). Theconcentrations of atmospheric Pb, in urban and non-urban atmospheres of Won Jucity (Korea), and its temporal and geographical distribution characteristics, havebeen studied in detail (Kim and Song, 1997). However, a database on concentra-tion, flux, fluctuations and distribution trends of lead at different representative sitesof a given urban area is of particular relevance to any future planning towards theimprovement and control of air quality.

In this article we have studied the month wise dust fall-out rate, concentrationof lead in the fall-out, its seasonal variation and dispersion pattern at 6 differentrepresentative sites, including industrial, commercial, residential and heavy trafficarea of the urban Raipur city of central India. The particulate fall-out rate andlead levels have been correlated with various meteorological parameters such astemperature, % humidity (relative), rain fall, etc.

2. Materials and Methods

2.1. STUDY AREA

Raipur (21◦14′ N, 81◦38′ E), the premier city of Chhattisgarh region of centralIndia (Figure 1), with an urban population of approximately 0.6 million, is literallysandwiched between two industrial complexes on its eastern and western outskirts.The western complex, at a distance of≈30 km, has at it’s nucleus the Bhilai SteelPlant and the Jamul Cement Factory as well as allied industries producing chemicalfertilizers and merchandise out of iron and steel. The eastern complex has a mixednature, including industries that extract oil from forest and farm products, or thosewho manufacture electrical goods, iron, steel, aluminium and copper. There arealso a few cement factories at Siltara, at an distance of≈15 km, and at Mandher,at an distance of≈30 km. The study area is the municipal corporation area of≈160 km2.

2.2. SAMPLING SITES

Depending upon the meteorological conditions and anthropogenic activities, theentire area under study, has been divided into 6 zones (Figure 1) as described below.

LEAD LEVELS IN THE AIRBORNE DUST PARTICULATES OF AN URBAN CITY 307

Figure 1.Geographical map of urban Raipur city in central India showing different sampling loca-tions and the yearly wind-rose pattern of the city, indicating % frequency of wind along with windvelocity.


Site #1: Birgaon is an industrial area, situated approximately 15–17 km from thecentre of the city i.e. Jaistambh, in a north-east direction of the city. Thisarea comprises an enormous number of big and small-scale agro-forest,iron, oil, etc. based factories and industries. There are houses for thefactory workers and other people who surround this site.

Site #2: Shankar nagaris a well planned residential area with a moderate pop-ulation, along with a few official government buildings and residences,located at abouth 6–7 km from Jaistambh in the east.

Site #3: Gudhiyari is an old and densely populated area of the city, situated at anaerial distance of abouth 7–8 km from Jaistambh in the north-west direc-tion. It comprises a wholesale market of essential household commodities.Residential buildings and houses in this part of the city are haphazardlyconstructed. Slums have also developed fast in this area.

Site #4: Ravishankar universityis situated in the south-west direction of the city ata distance of 6–7 km on the Great-Eastern national highway. The area en-circles approximately 200 acres of land. It is the largest centre for highereducation of this region of central India.

Site #5: Tikrapara, at a distance of about 8–9 km from Jaistambh in the south, is adensely populated slum area, with unplanned housing patterns. This areais adjacent to Vivekanand Sarovar, the largest water tank of the city.

Site #6: Jaistambhcan be regarded as the centre of the city. This particular areaexperiences heavy loads of traffic. Several thousands of motor vehiclespass daily through this square. There are a few multi-story buildings hereand this site is also densely populated.

2.3. SAMPLE COLLECTION AND DUST FALL MEASUREMENT

The dust fall measurements were carried out in accordance with the practice laiddown in previous literature (NEERI Report, 1981). The dust collection glass jarsused were cylindrical in shape with a diameter of 15 cm and a height of 45 cm. Inall, six sampling sites were selected in the study area. In each sampling site, fourseparate samplers were placed in different directions at a radial distance of 50 m forthe most precise sampling. All values obtained at a particular sampling site were,thus, the average of 4 samplings. Distilled water was placed in each of the collectorsto prevent sample loss by blowing air. Then the collectors were placed in positionin guard-frames at 5–15 m above the ground level, depending the obstructions inindividual sites (NAPRC Report, 1962). The jars were inspected every week, andwere replaced by fresh collection jars after a duration of 30 days. The pre- andpost-monsoon month measurements were made of dust fall rate and concentrationand flux of lead for a whole hydrological period in each sampling site.

The dust fall rate was calculated for each site using the following equation(Kikuo, 1977):

R= 1.273(W/D2)× (30/N)× 104


where,

R = dust fall rate (metric tonne (mt) km−2 month−1);

W = the total weight of dust fall-out in the collecting container (g);

D = the diameter of the dust collecting container (cm);

N = the number of days of collection of sample.

2.4. SAMPLE PREPARATION AND ANALYSIS OF LEAD

The dried particulate fall-out sample (0.1–0.5 g) was taken in a 50-mL beakerand leached with cold and concentrated HNO3 acid (2–4 mL). The residue afterfiltration was washed with dilute (1:10) HNO3 acid (3 mL) and then digested at60 ◦C with concentrated HCl:HNO3 (3:1) mixture (5 mL). The digested residuewas filtered and the filtrate was combined with the leachate and diluted to a knownvolume (25 mL) in a volumetric flask (GBC Manual, 1989).

Then, aliquots of these diluted samples were taken for analysing by atomicabsorption spectrometer (model GBC-AA 932). The wavelength, slit width, lampcurrent and fuel selected for Pb determination were, respectively, 217.0 nm, 0.1 nm,4 mA and C2H2 with air support. Appropriate dilutions were made in case ofsamples with higher lead levels. A calibration curve was prepared using differentconcentrations of Pb. Three repetitive measurements of each sample were takenand the values obtained for Pb concentrations, these three measurements were thenaveraged.

3. Results and Discussion

3.1. ANNUAL FLUX AND RATE OF DUST FALL-OUT

The total annual flux of airborne dust particulate has been calculated on the basis ofmonth wise measurements of dust fall rate at different sites of the urban city duringNovember 1996–June 1997. Figure 2 shows the monthly variation of dust fall-outrate in mt km−2 month−1 at different sampling locations of urban Raipur city. Themonthly dust fall rate were found to be in the range 3.0(±0.1)–91.3(±1.2) mt km−2

month−1 for all six sampling sites during the whole hydrological year. The lowestrate was at site 3 in December and the highest at site 1 in February. The monthwise variation of dust fall-out rate, mt km−2 month−1, for 8 sampling months atdifferent sampling sites as mean (n=4, for 4 samples obtained from all individualsites) dust fall rate were observed to be in the range 38.8(±0.6)–91.3(±1.2) insite 1, 7.0(±0.1)–42.0(±0.2) in site 2, 3.0(±0.1)–39.0(±0.2) in site 3, 5.5(±0.2)–54.6(±0.3) in site 4, 12.0(±0.2)–55.0(±0.7) in site 5 and 15.0(±0.1)–39.4(±0.4)in site 6. On the basis of observed month wise dust fall rate, for the present study,the highest total flux was calculated to be for site 1 with an amount of 893.1 mt


Figure 2.Monthly variation of dust fall-out rate and concentration of Pb at different representativesites of Raipur city.


km−2 yr−1. The values of annual flux in the other sites,viz. 2, 3, 4, 5 and 6, were251.7, 262.8, 375.9, 355.9 and 340.9 mt km−2 yr−1, respectively. Thus, on anaverage, the whole urban part of the city encircling an area of 160 km2 receivesa huge amount of 6.6× 104 mt airborne dust fall-out annually.

The highest value of observed dust fall was in the industrial area i.e. at site 1.The values of total flux obtained from sites 2, 3 and 5 were quite comparable. Thedifference between the sites 1, 4 and 6 were considerably large. Thus, observed datahave confirmed that particulate contributions from industrial plants and vehicularemissions are quite significant. As a consequence, air quality of all these sites, alsothe whole city, has been deteriorating.

3.2. LEAD LEVELS IN AIRBORNE DUST FALL-OUT

The analyses on month wise and site wise lead concentration inµg g−1, averagesite wise concentration of Pb inµg g−1 and annual site wise flux of Pb inµgkm−2 yr−1, at different sites for the whole study period, have been carried out.Figure 2 shows the monthly change in the Pb concentration in ppm orµg g−1

at various sampling sites during pre- and post-monsoon periods of Raipur city.The month wise variation of flux of lead in the airborne dust particulates, inµgg−1 dust, for 8 sampling months at different sampling sites as mean (n=5, for5 determinations of a single sample by AAS) lead concentration were observedto be in the range 38.8(±0.6)–91.3(±1.2) in site 1, 7.0(±0.1)–42.0(±0.2) in site2, 3.0(±0.1)–39.0(±0.2) in site 3, 5.5(±0.2)–54.6(±0.3) in site 4, 12.0(±0.2)–55.0(±0.7) in site 5 and 15.0(±0.1)–39.4(±0.4) in site 6. The concentration of leadat site 1 (industrial area) ranges between 0.100–0.792µg g−1 and at site 6 (heavytraffic zone) it ranges between 0.109–0.718µg g−1 dust fall. These are higher thanthe Pb concentrations found in commercial and residential sitesviz. 2,3,4 and 5.The Pb concentrations for other sites were in the range 0.001–0.098µg g−1 at site2, 0.032–0.148µg g−1 at site 3, 0.079–0.255µg g−1 at site 4 and 0.022–0.180µgg−1 of airborne dust particulates at site 5. Thus, on an average, the concentra-tion of Pb in the different sites was found to be 0.482±0.013µg g−1 in site 1,0.026±0.003µg g−1 in site 2, 0.081±0.006µg g−1 in site 3, 0.139±0.006µg g−1

in site 4, 0.087±0.006µg g−1 in site 5 and 0.353±0.005µg g−1 in site 6. Due to themaximum precipitation of airborne particulates, as well as highest concentrationof Pb in industrial areas, the flux of Pb is also maximum in this zone. The nexthighest flux of Pb is in heavy traffic areas. Site 2, Shankar nagar, receives the leastquantum of Pb and therefore this area is the least polluted. The amount of lead fallin all other sites is more or less the same. Thus, on an average, the whole urbanpart of the city, encircling an area of 160 km2, receives an alarming amount of17.6 kg Pb, annually. The maximum concentration of Pb in almost all stations wasobserved during winter and autumn (January–March). As a whole, the percentageconcentration of Pb in the total annual dust fall of the urban city is calculated to


Figure 3.Monthly variation of meteorological parametersviz. temperature, wind velocity, humidityand rainfall of the study area during one hydrological year.

be 2.67×10−5%. The occurrence of lead levels was found in different areas in thisorder: industrial> heavy traffic> commercial> residential.

3.3. SEASONAL VARIATION OF AIRBORNE DUST FALL AND

METEOROLOGICAL FACTORS

A systematic study of meteorological parameters has been carried out. Figure 3shows the graph of monthly variation of the meteorological parametersviz. temper-ature, wind velocity, humidity and rainfall of the study area during one hydrologicalyear. The city has an extreme climate, the monthly average day temperature variesfrom a minimum of 23.9◦C in winter (January) to a maximum of 42.4◦C in sum-mer (May). The minimum temperature recorded in a day is 4.5◦C in January and


the maximum temperature recorded in May is 47.5◦C. The annual rainfall recordedis about 1264 mm. In summer, the monthly average relative humidity (RH) lowersdown to 40.5% (May). Annually it ranges between 40.5 (May)–90% (Novemberand January). The monthly average wind speed varies from 1.4 (November) to 8.0km hr−1 (June). The right inset-picture of Figure 1 shows the wind-rose pattern ofthe city, indicating the maximum frequency in the total number of days in a year,along with the variation in wind velocity. The predominant wind direction (PWD)is, thus, north-east (NE) (17%) and south-west (SW) (14%). The percentage ofcalm has been noted on 32% of the days of the year.

The correlation coefficient values (r) of dust fall rate (DFR) and lead concentra-tion (LC) in dust fall, at different sampling locations with various meteorologicalparameters, have been calculated, and in some cases strong correlations have beenobserved. The ‘r’ value of ‘DFR’ at different locations with temperature (T), windvelocity (WV), % relative humidity (%RH) and rain-fall (RF) are shown in par-enthesis (rT, site 1 = 0.72, rT, site 2 = 0.27, rT, site 3 = 0.44, rT, site 4 = 0.35, rT, site 5 =0.10, rT, site 6= 0.37; rWV, site 1= 0.98, rWV, site 2= 0.22, rWV, site 3= 0.50, rWV, site 4=0.39, rWV, site 5 = 0.10, rWV, site 6 = 0.48; rRH, site 1 = 0.50, rRH, site 2 = 0.34, rRH, site 3

= 0.60, rRH, site 4 = 0.58, rRH, site 5 = 0.14, rRH, site 6 = 0.42; rRF, site 1 = 0.81, rRF, site 2

= 0.31, rRF, site 3 = 0.10, rRF, site 4 = 0.12, rRF, site 5 = 0.11, rRF, site 6 = 0.59). Again,the ‘r’ value of ‘LC’ at different locations with the meteorological parameters areshown in parenthesis (rT, site 1= 0.14, rT, site 2= 0.68, rT, site 3= 0.53, rT, site 4= 0.63,rT, site 5 = 0.51, rT, site 6 = 0.10; rWV, site 1 = 0.37, rWV, site 2 = 0.81, rWV, site 3 = 0.70,rWV, site 4 = 0.65, rWV, site 5 = 0.20, rWV, site 6 = 0.29; rRH, site 1 = 0.17, rRH, site 2 =0.58, rRH, site 3= 0.30, rRH, site 4 = 0.35, rRH, site 5= 0.86, rRH, site 6 = 0.12; rRF, site 1=0.34, rRF, site 2 = 0.30, rRF, site 3 = 0.70, rRF, site 4 = 0.60, rRF, site 5 = 0.40, rRF, site 6 =0.54). Thus, from the data above, it may be inferred that the meteorological factorsplay an important role in the deposition of dust fall and the flux of lead in allsampling sites, except in a few cases.

A positive correlation of lead concentration with %RH is observed. RH is lower-ed slowly from winter to summer. In a similar manner, seasonal variation of humid-ity bears significant positive correlation with dust fall rate. A monthly average valueof wind velocity 1.9–2.5 km h−1 (during January to March) shows maximum leadfall-out in all sites except site 2. It is clear that sampling site 2, Shankar nagar, isthe least polluted area. The most polluted area (maximum concentration of Pb) aresite 1 and 6viz. Birgaon, the industrial area and Jaistambh, the heavy traffic area.This is because of the industrial activities in Birgaon and the vehicular emissionsand traffic load in Jaistambh. Due to rigorous increases in wind velocity in summer,the particulate fall-out do not settle down and, hence, tend to be dispersed in theatmosphere for a longer time or are dragged away by wind, which is evident fromthe observed results.

It is observed from the results that site 1, the industrial area, shows positive cor-relation with rain fall but no significant relationship with humidity and temperature,because of the local emission source.


It is clear from the obtained results that the sampling sites 1, 5 and 6 showmaximum concentration of particulate pollutants. Figure 1 indicates that sites 1and 6 are at a down wind direction. These sites are situated at north-west (NW)and south-east (SE) directions, respectively. Sites 2, 3 and 5 (NE, SW) show highestupward wind direction. The Birgaon, the industrial site, had the positive effect ofthe favourable wind direction and the locally situated emission source, resultingin a higher value of dry deposition. Jaistambh too had its local emission source asautomobile exhausts, etc. But the high values at Tikrapara (in SE direction) may bedue to anthropogenic or other extraneous reasons. The present study indicates thatdispersion of pollutants also depends on wind direction.

The rate of dust fall-out has also been found to be affected by extraneous contri-bution resulting from local factors like dense population, road traffic, etc., resultingin some anomalies in the observed results. It is quite clear (Figures 2 and 3) thatthe rate of dust fall-out in almost all sites is higher with lower temperature, andthe dust fall rate and lead concentration is the highest between January and March,except in Shankar nagar, site 2.

4. Conclusion

From the present study on the airborne dust fall-out and lead levels, the followingsignificant points can be inferred.

1. The urban part of the city receives a significant amount of the dust fall-outin the range 3.0(±0.1)–91.3(±1.2) mt km−2 monthly, for all sampling sitesduring the whole hydrological year. The maximum quantum of airborne partic-ulates is in the industrial area and the minimum in the residential area. The city,thus, receives a huge annual flux of 6.6×104 mt airborne dust particulates.

2. The lead concentration in dust fall-out was found to be in the range 0.001–0.718µg Pb g−1 of airborne dust fall-out for all 6 selected sites during thecourse of study. Thus, the annual flux of Pb in the urban city is an alarmingamount of 17.6 kg.

3. The meteorological parametersviz. temperature, relative humidity, wind velo-city and wind direction, have shown positive correlation with the quantum ofdust fall in a particular site as well as in a particular season. The maximumfall-out was observed at lower temperatures, higher relative humidity, lowervelocity of wind and across the wind direction.

4. The distribution trend of airborne dust fall-out in the city was found to be inthe following order: industrial area> heavy traffic area> commercial area>residential area.

5. The maximum concentration of lead in the airborne particulates of industrialareas could be due to its source as emission through stacks of Cu and Pb etc.bearing alloy industries and other industries. The higher lead levels in the


particulates of heavy traffic area is quite obvious and is due to the vehicularemission, apart from the other contributing sources. Anthropogenic activities,wind velocity and wind directions are the major contributing sources of dustfall-out and lead in the dry deposition in all other sites.

Acknowledgements

This study was supported by a Grant from the Madhya Pradesh Council of Scienceand Technology, MAPCOST, Bhopal under the project code Env. Sci. 56/95. Theauthors also acknowledge the valuable guidance and help rendered by Meteorolo-gical Department of Agriculture College, Raipur, Dr. M.P. Gupta, School of Studiesin Geography, Pt. Ravishankar Shukla University, Raipur and Prof. M.C. Gupta,Director, National Environmental Engineering Research Institute, NEERI, Nagpur,India.

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Lead Levels in the Airborne Dust Particulates of an Urban City of Central India