Chemical Characteristics of Aerosols and Trace Gas

Chemical characteristics of aerosols and trace gasdistribution over North and Central India

Khem Singh & D. P. Singh & C. K. Dixit &Nahar Singh & C. Sharma & S. Sahai &Arvind K. Jha & Z. H. Khan & Prabhat K. Gupta

Received: 6 January 2011 /Accepted: 27 July 2011# Springer Science+Business Media B.V. 2011

Abstract A field campaign on aerosol chemicalproperties and trace gases measurements was carriedout along the Delhi–Hyderabad–Delhi road corridor(spanning about 3,200 km) in India, during February1–29, 2004. Aerosol particles were collected onquartz and cellulose filters using high volume(PM10) sampler at various locations along the route(i.e., urban, semi-urban, rural, and forest areas) andhave been characterized for major cations (Na+, Ca2+,Mg2+, K+, and NH4

+), anions (Cl−, NO3−, and SO4

2−),and heavy metals (Cu, Cd, Fe, Zn, Mn, and Pb).Simultaneously, we measured NO2 and SO2 gases.These species show large spatial and temporalvariations. The ambient PM10 concentration has beenobserved to be the highest (55±4 μg m−3) near semi-urban areas followed by forest areas (48±2 μg m−3)and in rural areas (44±22 μg m−3). The concen-trations of NOx (NO2+NO) and SO2 ranged from 16to 69 μg m−3 and 4 to 11 μg m−3, respectively.Among anions, NO3

− and SO42− are the major

constituents of PM10. The urban and semi-urban sites

showed enhanced concentrations of Fe, Zn, Mn, Cd,and Pb. This study provide information about atmo-spheric concentrations of various species in thenorthern to central India, which may be importantfor policy makers to better understand the air qualityof the region.

Keywords PM10. Cations . Anion . NOx and SO2

.

Heavymetals

Introduction

Aerosol particles of different sizes and compositionplay an important role in the control of manyatmospheric processes, e.g., cloud formation, visibility,solar radiation transfer (Bodhaine 1983; Pueschal et al.1986; Shaw 1987), deposition of different compounds,acidification of rain, smog, fog, etc., which affect theclimate, water, and human health (Dockery et al.1993). Airborne particles with an aerodynamic diam-eter of <10 μm (PM10 or respirable suspendedparticulate matter) are considered as inhalable particlesand have been found to be widely associated withrespiratory health problems in human. Gases andparticulate matter, both contribute to deterioration ofair quality (Parmar et al. 2001). Water-soluble ioniccompounds contribute more to fine aerosol, indicatingmore health-related risk (Bencs et al. 2008). Aerosolsare largely spread over long regions (Chan et al. 1997;Wakamatsu et al. 1996) because fine aerosols are

Environ Monit AssessDOI 10.1007/s10661-011-2284-3

K. Singh :D. P. Singh : C. K. Dixit :N. Singh :C. Sharma : S. Sahai :A. K. Jha : P. K. Gupta (*)National Physical Laboratory-CSIR,Dr. K. S. Krishnan Marg,New Delhi 110012, Indiae-mail: [email protected]

Z. H. KhanDepartment of Physics, Jamia Millia Islamia,New Delhi 110025, India

lighter in mass and remain suspended in air for severaldays (Wojicik and Chang 1997). Gas-phase SO2 andNO2 released into the environment due to natural oranthropogenic processes are oxidized mainly to partic-ulate phase, sulfate, and nitrate, respectively, and alsosuch trace gases pose health-related problems (Dockeryet al. 1993). Secondary aerosols are considered to bevery important when atmospheric nutrient loading of awater body is considered (Horemans et al. 2009).Acidic aerosols can react with gaseous ammonia (NH3)to form ammonia salts (Koutrakis et al. 1988), whichhave impact on atmospheric processes and humanhealth (Vincent 1989).

In this paper, we present the results of a fieldcampaign funded by Indian Space Research Organi-sation to study the atmospheric compositions alongthe Delhi–Hyderabad-Delhi road corridor route(Northern and Central India) during the periodFebruary 1–29, 2004. The latitudinal and longitudinalcoverage for this campaign was from 17.3o to 28.6oNand 77.2o to 78.2oE, respectively, and the routecovered several diverse ecosystems like urban (U),semi-urban (SU), rural (R), and forest (F) areas. Theresults of this case study, i.e., chemical character-izations of aerosols and trace gases for variouslocations along the Delhi–Hyderabad–Delhi roadcorridor in India can be useful for policy maker tobetter understand the air quality issues.

Methodology

Sampling sites

Samplings were done at different sites representingdiverse ecosystems (Fig. 1) along Delhi–Hyderabad–Delhi road (National Highway), which covers nearly3,200 km and passes through five States, i.e., UttarPradesh, Rajasthan, Madhya Pradesh, Maharashtra,and Andhra Pradesh (Table 1). All sampling locations(11 sites) were about 200 to 500 m away from thehighway (wind direction was from site to road side) toavoid traffic influence. Among these sites, Hyderabadand Nagpur are big cities (urban areas) with popula-tion of 3.69 million and 4.05 million, respectively(2001 census). Kosi site lies about 2 km away upwindthe highway. Dholpur is in the arid regions ofRajasthan, whereas Khajuraho represents a semi-urban environment, and Orchha site is surrounded

by the thick Teak (tall Asian tree) forest. Sampling atSagar site was done about 15 km away from the maincity, which is situated on the foothills of Vidhyanchalmountain ranges and Jabalpur site surrounded by hillsand some villages within the radius of 12 km.Agricultural fields surrounded the Nirmal site. Kuraisite is situated in the south of Jabalpur and was about4 km inside the forest. Sampling site in Nagpur waslocated inside the campus of National Environmentaland Engineering Research Institute (NEERI), which isnear to the residential area. Sugarcane trash burningactivities was observed at Ramampeth (rural site).Shadnagar–Hyderabad (Hyd) site is located 80 kmtowards the south of Hyderabad, where the measure-ment was made round the clock (i.e., 0600–1800–0600 hours) continuously for 5 days, i.e., fromFebruary 16–21, 2004. There was a fire event onFebruary 19, 2004 in the city area and is consideredas an episodic event day. Meteorological parameters(Fig. 2), i.e., average ambient temperature, pressure,and wind speed and direction, for each sampling siteswere recorded from in situ measurements, and alsotaken from the Indian Metrological Department for oneor two locations where we missed the recording ofmeteorological data. Relative humidity was observed tobe low at most of the sites.

Aerosol and trace gas sampling and chemicalcharacterization

Aerosol samples were collected on pre-heated, pre-weighed, and desiccated Whatman Quartz micro-fiber(QM-A) and Cellulose Whatman 41 filter papers (size,203×254 mm) at various sites using a high volumesampler (Model: HVS/R, Netel Chromatographs), whichcan collect particles <10 μm (PM10) at a flow rate of1.0±0.2 m3 min−1. Sampling duration varied from 4 to6 h at all sites except measurement made at Hydbecause of the logistic arrangement. Gas-phase NOx

(NO+NO2), NO2, and SO2 were collected by passingambient air at a flow rate of about 1 Lmin−1 throughthe glass impingers placed in sequence containingsodium arsenite (0.008 M), sodium hydroxide (0.1 M)solution (Jacob and Hocheisser 1958), and potassiumtetra-chloromercurate solution (0.04 M; West andGaeke 1956), respectively, and determined by thecolorimetric method by an UV–visible spectrophotom-eter. Further, for NO2 sampling, ambient air was passedvia chromic acid (CrO3) trap to oxidize ambient NO

Environ Monit Assess

into NO2 (Levaggi et al. 1974). NO is calculated as adifference between NOx and NO2.

Each aerosol loaded filter was folded in half face toface and preserved. Filters were equilibrated indesiccators for 48 h before weighing and chemicalanalysis. The mass of aerosols collected was obtained

gravimetrically using a micro-electronic balance(OHAUS, Model: GA 200D; range max, 110 g;accuracy, 0.1 μg). Chemical characterization ofaerosols has been done for cations and anions ofwater-soluble aerosol components, and acid solubletrace heavy metals.

Fig. 1 Sampling sites along the Delhi–Hyderabad–Delhi road corridor route

Table 1 Description of the sampling sites

Sampling site Period Latitude/longitude Ecosystem type Meteorological conditions observed during sampling

Chhatha/Kosi Kalan 2 Feb 27°49′N–77°25′E SU Clear atmosphere, medium wind

Orchha 4 Feb 24°18′N–77°37′E F River basin, stony area, moderate wind

Sanuda/Sagar 7 Feb 23°53′N–78°54′E R Stony soil, clear sky, medium winds

Tikaria/Jabalpur 9 Feb 23°22′N–80°04′E R Vegetation, clear sky, slow wind with dust

Pipertutha/Kurai 11 Feb 21°46′N–79°31′E F Inside forest, clear sky, slow wind

Bussapur/Nirmal 14 Feb 18°57′N–78°23′E R Clear sky, wind with sand particles

Shadnagar/Hyderabad 16–21 Feb 17°1.7′N–78°11.3′E SU Clear sky, normal winds

Ramampetha 22 Feb 18°07′N–78°27′E R Sugarcane trash burning, clear sky, medium wind

Nagpura 23 Feb 21°07′N–79°04′E U Thick vegetation and buildings

Achnar/Khajurahoa 27 Feb 24°52′N–79°56′E SU Hilly area

Sagarpada/Dholpura 29 Feb 26°40′N–77°54′E SU Near Chambal river, arid area

U urban, SU semi-urban, R rural, F foresta Indicates return journey sites


Water-soluble chemical species

Water-soluble aerosol components from filter cut areaof 25 cm2 were extracted with 20 ml deionized waterfor 30 min by ultrasonication (model: Elma, Transonic700/H). The extracted volume, after filtration throughWhatman 41 cellulose filters, was made up to 50 mlwith deionized water and kept in pre-washed polyeth-ylene bottles after little addition of thymol (Gillet et al.1992; Granat et al. 1992) as preservative and stored inrefrigerator. Major cations, i.e., Na+, Ca2+, Mg2+, andK+, in the extract were analyzed by flame atomicabsorption spectrophotometer (FAAS, Analytik JenaVario, Germany), whereas Cl−, NO3

−, and SO42− were

analyzed by ion chromatography (Dionex 761) withMETROSEP column of size 3.0×150 mm. Ammonium(NH4

+) was determined before adding thymol, byindophenol blue method (Weatherburn 1967) using

a UV–VIS Spectrophotometer (Model Lambda 3b,Perkin Elmer). The quality assurance in determina-tion for various species as above was done by usingcertified reference materials or Bhartiya NirdeshakDravyas of National Physical Laboratory, India andNational Institute of Standards and Technology,USA traceable standards.

The extraction of trace heavy metals was donefrom each filter sample cut area of 25 cm2 (includingfilter blank), with 20 ml of 5% HNO3 solutionultrasonically for 2 h (Ho et al. 2003) and filteredthrough Whatman 41 cellulose filters, diluted to 50 mlwith deionized water and stored in polyethylenebottles in the refrigerator until their chemical analysis.FAAS was used to determine Fe, Zn, and Mn, whileCu, Cd, Al, and Pb were analyzed using graphitefurnace atomic absorption spectrophotometer (GFAAS,Analytik Jena, Germany).

0

50

Tem

pera

ture

0 C

0

50

100

Hum

idit

y%

0

200

400

Win

d D

ir,

degr

ee

0

2

4

6W

ind

spee

d,

m s

-1

755

760

765

Del

hi

Kos

i

Dho

lpur

Kha

jura

ho

Orc

hha

Saga

r

Jaba

lpur

Kur

ai

Nir

mal

Ram

ampe

th

Hdy

Hdy

Hdy

Hdy

Hdy

Location

Pre

ssur

e, m

mH

g

Fig. 2 Average meteorolog-ical parameters withstandard deviation atsampling sites


Results and discussion

The spatial variation of PM10 mass concentrations ofaerosols at each sampling site are discussed elsewhere(Gupta et al. 2007) and was found to be in the rangeof 27 to 75 μg m−3. It has been found that PM10

loadings of different ecosystems are 54±5 μg m−3 forurban areas, 48±2 μg m−3 for forest areas, and 44±22 μg m−3 for rural areas, respectively. The PM10

levels at Nagpur and Hyderabad were 40 and51 μg m−3, respectively, which are comparativelylower than the values observed earlier at these sites, i.e.,79 and 73 μg m−3, respectively (NEERI 2000).

Major ionic species

Figure 3a, b, c shows spatial variation in theconcentrations of the major cations, anions, and heavymetals in PM10 aerosol samples from differentlocations. Figure 4 shows that the ratio of total solubleions species (cations + anions) to PM10 is higher atSagar (85%) than that of other sites. The ratio of sea saltfraction (Na++Cl−) to total soluble ions species variesfrom 13% to 72% with the maximum value found atJabalpur. Whereas Na+ and Cl− were found to be in therange of 0.13 to 1.69 and 1.16 to 13.10 μg m−3,respectively, and the range of molar ratio of Na+/Cl− isfrom 0.02 to 0.65. The other species are SO4

2− (16% to83%) with the maximum at Hyderabad, whereas NO3

−

(13% to 31%), followed by NH4+, Cl−, Ca2+, and Mg2+

having the maximum at Ramampeth. It has been foundthat anions concentrations (Cl−, SO4

2−, and NO3−) are

higher at semi-urban sites (Kosi, Cl− 13.1 μg m−3 andHyderabad, SO4

2− 10 μg m−3) as compared to ruralsites, i.e., Sagar, Jabalpur, Nirmal, and Ramampeth(Fig. 3a). Among these, Sagar site has a higher totalionic concentration value of 27.3 μg m−3, which showsdominance of industrial sources. Cl− has been found tobe higher at Kosi and lower at Nirmal (1.2 μg m−3),indicating dominance of industrial sources at Kosi,which has an industrial area with large industries thatare in function. The Cl− value at Hyderabad andNagpur has been observed to be 2.6 and 1.4 μg m−3,respectively, which are much lower than 11.1 and10.8 μg m−3, respectively, observed in a previous studyduring February 1996 (NEERI 2000). SO4

2− concen-tration varies from 2.7 to 10 μg m−3 with the maximumconcentration of 10 μg m−3 observed at Hyderabad.NO3

− is also one of the major constituents of the urban

atmospheric aerosols (Hidy et al. 1975). Particulatenitrate is largely produced through the photo-oxidationof NO2, derived from combustion of fossil fuels (Logan1983). In Nagpur, it accounts for only a small portion ofthe PM10 mass concentrations (3%). The variationobserved for NO3

− in the PM10 is from 1.2 to6.8 μg m−3 with the minimum at Khajuraho(1.4 μg m−3) and the maximum at Hyderabad(6.8 μg m−3; Fig. 3a). The concentration of NO3

− atNagpur (1.2 μg m−3) was lower than the reportedvalues in a previous study (2.8 μg m−3) in February1996 (NEERI 2000), whereas the value at Hyderabad indaytime (6.8 μg m−3) was found to be higher than theearlier reported values, i.e., 1.55 μg m−3 (NEERI 2000).

Na+, Ca2+, and Mg2+ that originated from naturalsources, like sea salts, were found to be dominantlydistributed in aerosols (Khare et al. 2004). Figure 3bshows that the concentration of Ca2+ has been foundto be the highest at Sagar and minimum at Jabalpur,while Mg2+ has been observed to be higher atRamampeth and lowest at Kurai. The higher valueof Ca2+ and Mg2+ can be due to sea salt andsuspension of local soil dust (Horemans et al. 2009).The value of K+ has been observed to be the maximumat Ramampeth and minimum at Orchha, which may bedue to sugarcane trash burning at farming site, thoughthe value of PM10 is higher at Orchha as compared toRamampeth, indicating the greater contribution ofnatural sources at Orchha. The biomass burningcontributes to enhanced the concentration of K+

(Echalar et al. 1995; Cooper 1980; Kleinman et al.1979). NH4

+ concentration was found to be0.09 μg m−3 at Dholpur and 0.01 μg m−3 at Nagpur.

Heavy metals

The concentrations of heavy metals in the PM10

aerosol samples collected at different sites are shownin Fig. 3c. Al is normally used as the crustal indicatorelement and the enrichment factor (EFcrust) is calcu-lated according to following equation (Chester et al.2000),

EFcrust ¼ Cxp=CAl

� �= Cxc=CAlcð Þ;

Where Cxp and CAl are the concentrations of anelement x and Al, respectively, in aerosol, and Cxc andCAlc are their concentrations in an average crustalmaterial (Murthy et al. 1982). By convention, an


arbitrary EFcrust value of <10 indicates that a tracemetal in aerosol has a significant crustal sourcetermed as non-enriched elements and EFcrust>10 isconsidered to indicate a non-crustal source, termed asthe anomalously enriched elements (AEEs; Peirson etal. 1974; Fig. 5).

At Dholpur, higher concentrations of Fe (2.29×103 ng m−3), Zn (1.45×103 ng m−3), Mn (0.26×103 ng m−3), and Pb (0.02×103 ng m−3) have beenobserved, whereas at Kosi, Cd (0.31×103 ng m−3) andat Nagpur, Cu (0.14×103 ng m−3) showed the highestconcentrations (Fig. 3c). The lowest concentration of

0

3

6

9

12

15

Kos

i

Dho

lpur

Kha

jura

ho

Orc

hha

Saga

r

Jaba

lpur

Nir

mal

Kur

ai

Nag

pur

Ram

ampe

th

Hyd

Day

Hyd

Nig

ht

Hyd

Epi

sodi

c

LocationC

once

ntra

tion

,µg

m -3

C

once

ntra

tion

,µg

m -3

Cl NO3 SO4

0.00.51.01.52.02.53.03.54.0

Kos

i

Dho

lpur

Kha

jura

ho

Orc

hha

Saga

r

Jaba

lpur

Nir

mal

Kur

ai

Nag

pur

Ram

ampe

th

Hyd

Day

Hyd

Nig

ht

Hyd

Epi

sodi

c E

vent

Location

Na Ca Mg K NH4

050

100150200250300350

Kos

i

Dho

lpur

Kha

jura

ho

Orc

hha

Saga

r

Jaba

lpur

Nir

mal

Kur

ai

Nag

pur

Ram

ampe

th

Hyd

Day

Hyd

Nig

htH

ydE

piso

dic

Location

Mn,

Cu,

Cd,

Pb,

Al

(ng

m-3

)

200

700

1200

1700

2200

2700

Fe,

Zn

(ng

m-3 )

Mn Cu Cd Pb Al Fe Zn

a

b

c

Fig. 3 Spatial variation in aanions, b cations, and cmetals concentration atdifferent sampling sites


Al, Fe, Mn, Cu, Zn, Cd, and Pb has been observed atall the rural sites. No significantly higher value ofEFcrust for Pb was observed at any sites Fig. 5.

Ionic enrichment factor

To indicate the extent of the contribution of sourcesother than sea salts to the particulate concentration ofthe ion, EF has been calculated by considering Na+

from sea water (Duce et al. 1983). It can be seen fromTable 2 that for most of the ions, EFs are higher at allthe sites, except at Ramampeth and Hyderabad, whichshow comparatively lower values of Cl−. Anthropo-genic activities and crustal sources may be responsiblefor higher EFs. At all the sites, a significant fraction ofCa2+ and Fe may also be emitted from anthropogenicactivities such as industries, fossil fuel combustion, etc.(CUPS 1981–1982; CUPS 1987). The heterogeneousreactions of gaseous SO2 and HNO3 might have alsocontributed in the observed values. The SO4

2− andNO3

− may be attributed to form from gaseous absorp-tion of SO2 and HNO3 on preexisting particles byheterogeneous reaction. We have observed a goodcorrelation (r2=0.77) between SO4

2− and SO42−+SO2,

which suggest that SO42− may have been largely

produced by secondary processes. Similarly, NO3− is

also suggested to form through secondary processes.However, in our case the correlation between NO3

− andNO3

−+NOx is poor (r2=0.03), which possibly due to

evaporation losses of NO3− during atmospheric high

humidity conditions. An increase in the air temperaturemay lead to the biodegradation of ammonium saltspresent and the low humidity may result in NH3

emissions in the gas phase. The transformation ofNH3 into particulate NH4Cl and NH4NO3 increaseswith decreases in temperature (Allen et al. 1989; Tanakaet al. 1987). The concentration of NH4

+ has been foundto be higher at Dholpur, Nirmal, and Hyderabad. Fromthis study, it is observed that a decrease in airtemperature results in an increase in the concentrationof particulate NH4

+.NH4

+ particles in the atmosphere are believed to beexisted largely as (NH4)2SO4 and NH4NO3. Both arehygroscopic in nature; however, evaporation losses ofNH4NO3 particles are reported widely. In our study, theNH4

+ show good correlation with NO3− (r2=0.59) and

non-sea salt (nss) SO42− (r2=0.50). When considering

the variation of NH4+, the contribution of NH4Cl in

addition to (NH4)2SO4 and NH4NO3 should be takeninto the account. NH4Cl can be formed at lowtemperature by the reaction of NH3 and HCl (Pio andHarrison 1987) as per the following equation.

NH3 gasð Þ þ HCl gasð Þ ¼ NH4Cl particleð Þ

The maximum amount of NH4Cl can be estimatedby excess of Cl− after determining the amount of seasalt Cl−. The excess value of Cl− (denoted as ΔCl−)

0

10

20

30

40

50

60

70

80

90

Kos

i

Dho

lpur

Kha

jura

ho

Orc

hha

Saga

r

Jaba

lpur

Nir

mal

Kur

ai

Nag

pur

Ram

ampe

th

Hyd

Day

Hyd

Nig

ht

Hyd

E

piso

dic

Solu

ble

ions

fra

ctio

n in

PM

10, %

Location

Na+ClNO3SO4Ca+Mg+K+NH4Total soluble ions

Fig. 4 Spatial variation infraction of major ions withrespect to PM10


beyond the values of the sea salt in aerosols werecalculated using Na+ concentration as an indicator ofsea salt. ΔCl− (= Clobs

− − Clsea−, where Clobs

− andClsea

− denote the observed and sea salt ratio of Cl−

concentration in PM10 aerosols, respectively) is auseful indicator to find out anthropogenic and sea saltcontributions. The positive value of ΔCl− in most of

the sites reveals that contribution may be primarilydue to anthropogenic sources, whereas the negativevalue shows dominance of the sea salt contribution.

Some fractions of the emitted SO2, through theheterogeneous reactions, are oxidized to sulfateaerosols (Cheng et al. 2000). Using Na+ as a tracerof sea salt, excess sulfate (nss SO4

2−) was calculatedas below (Millero and Sohn 1992).

nss SO42� ¼ SO4

2� � 0:251Naþ

The factor of 0.251 is the average molar ratio ofSO4

2− to Na+ in bulk sea water. More than 90% of thesulfate observed in the PM10 is nss SO4

2− at all thesites (Fig. 6). It is found that the SO4

2− concentrationat the semi-urban site is larger than the rural andforest sites except at Sagar and Nirmal, which arerural sites. The formation of secondary SO4

2− can beexplained by calculating the fs value, which is themole fraction of nss SO4

2− in total sulfur oxides, andis determined by

fs ¼ nss SO42�= SO2 þ SO4

2��

As mentioned by Ohta and Okita (1990), fs>0.1suggests the occurrence of SO4

2− formation in theatmosphere. At all the sites, the values of fs exceed0.1 with the maximum values observed at Dholpurand Hyderabad (Fig. 6). The higher value of SO4

2− at

Table 2 Ionic enrichment factors with respect to Na fordifferent sampling sites

Location Enrichment Factor

Cl− SO42− Ca2+ K+ Mg2+

Kosi 15.9 54.9 16.6 15.6 2.9

Dholpur 23.9 169.5 66.4 108.2 12.6

Khajuraho 1.9 7.3 4.5 1.6 0.7

Orchha 3.3 14.6 3.4 1.8 1.0

Sagar 3.7 17.1 28.9 2.0 0.5

Jabalpur 8.5 19.5 3.7 3.2 1.4

Nirmal 5.1 221.6 20.7 18.3 8.8

Kurai 9.0 48.7 6.9 7.7 2.0

Nagpur 5.8 142.7 41.5 115.8 6.4

Ramampeth 0.9 5.3 14.1 43.8 1.3

Hyd Day 1.2 24.0 15.1 18.0 0.7

Hyd Night 1.8 32.8 20.3 23.2 1.1

Hyd Episodic 1.0 26.2 14.1 38.9 0.9

0

10

20

30

40

50

60

70

Kos

i

Dho

lpur

Kha

jura

ho

Orc

hha

Saga

r

Jaba

lpur

Nir

mal

Kur

ai

Nag

pur

Ram

ampe

t

Hyd

Day

Hyd

Nig

ht

Hyd

Epi

sodi

c

Location

EF c

rust

Cu Fe Zn Mn Cd PbFig. 5 Enrichment factorindicating crustal andnon-crustal source forheavy metals


0

2

4

6

8

10

12

Kos

i

Dho

lpur

Kha

jura

ho

Orc

hha

Saga

r

Jaba

lpur

Nir

mal

Kur

ai

Nag

pur

Ram

ampe

th

Hyd

Day

Hyd

Nig

ht

Hyd

Epi

sodi

c

Location

nss

SO42-

,µg

m-3

0.0

0.1

0.2

0.3

0.4

0.5

0.6

fs

nss SO4 fs

Fig. 6 Secondary SO42−

(fs) and excess sulfate(SO4

2− excess) concentra-tion variation at differentsampling sites

--K

osi

Dho

lpur

Kha

jura

hoO

rchh

aSa

gar

Jaba

lpur

Nir

mal

Kur

aiN

agpu

rR

amam

peth

Hyd

Day

Hyd

Nig

htH

yd E

piso

dic

0.000.050.100.150.200.25

Location

SO42-

/PM

10

0.40.60.81.01.21.4

SO42-

/ SO

2

0.00

0.01

0.02

0.03

0.04

Ca2+

/ P

M 10

01020304050

Ca2+

/ SO

42-

Fig. 7 Ratios of aCa2+/SO4

2−, b Ca2+/PM10,c SO4

2−/SO2, andd SO4

2−/PM10


all site may be explained with the movements ofdiesel vehicles during sampling periods or long rangetransport of sulfur can also be possible reason (Bencset al. 2008).

SO42−–PM10–Ca

2− correlation

SO42− to Ca2+ (Fig. 7) ratio ranged from 0.02 to 0.08

with exception at Sagar (0.16) and Ramampeth (0.29).High correlations (r2=0.58–0.78) were observedamong crustal elements (Al, Ca2+, Fe, and Mg2+) atall sites. However, elemental species related to anthro-pogenic sources, such as Pb and Zn, are found to beaccumulated in PM10 particles. The Ca2+ concentra-tions at Sagar have been observed to be 1.23 μg m−3.Ca2+ to PM10 ratio is found to be lower at all locationsother than Sagar and Ramampeth.

SO2–SO42−–PM10 correlation

SO2 is oxidized to SO42− and accounted for particu-

late sulfate (Novakov et al. 1974). Figure 7 shows thecomparative ratio of SO4

2− to SO2 for variouslocations of this study. According to Ohta and Okita(1990) SO4

2− originates only from primary sources, iffs<0.1, whereas SO4

2− is substantially formed by

photochemical oxidation, in the smaller size fractions(Horemans et al. 2009). SO4

2− to PM10 ratio iscomparable at most of the locations. The ratio ofSO4

2−/SO2 at different locations varies from 0.50 to1.39. The possible reason for the lower ratio at Kuraiand Jabalpur site includes lower levels of PM10 andSO2, which possibly represents the equilibriumbackground concentration at which appreciable con-version of SO2 may not take place as in the case ofother sites. SO4

2− levels at Dholpur (Near Agra city)have been found to be comparable to values observedearlier at nearby Agra (14.67 μg m−3; Kulshrestha etal. 1995).

Trace gases

Figure 8 shows the variation of short lived trace gases,e.g., NO, NO2, NOx, and SO2, observed at differentsites. The nitrogen oxides (NOx) concentrations atdifferent sites varied from 15.9 to 69.2 μg m−3 withlowest value at Nirmal (15.9 μg m−3) and the highest atNagpur (69.2 μg m−3). The concentration of NO2

observed at Nagpur (63.6 μg m−3) was higher than theearlier reported value (8 μg m−3; NEERI 2000), but forHyderabad, the concentration of NO2 (19.4 μg m−3)showed similarity with previously reported value

0

10

20

30

40

50

60

70

80

Kos

i

Dho

lpur

Kha

jura

ho

Orc

ha

Saga

r

Jaba

lpur

Nir

mal

Kur

ai

Nag

pur

Ram

ampe

th

Hyd

erab

ad

Hyd

Fir

e E

vent

Location

NO

x, N

O2

& N

O

Con

cent

rati

on, µ

g m

-3

0

2

4

6

8

10

12

SO2

µg

m-3

NOx NO2 NO SO2Fig. 8 Spatial variations intrace gases concentrationsat different sites


(20 μg m−3; NEERI 2000). The NO showed variationsfrom 0.1 to 5.6 μg m−3 at Sagar and Nagpur,respectively. SO2 concentrations at different sitesvaried from 3.9 to 11 μg m−3 with lowest value atRamampeth and the highest at Sagar.

Conclusions

An intensive ground-based measurement campaignfor the study of ambient aerosols and trace gases wasperformed in February 1–29, 2004 along the Delhi–Hyderabad road corridor covering urban, rural, andforest sites. At some places industrial sources alsoseem to contribute to the aerosol loading. Aerosolchemical composition data shows large spatial andtemporal variations in concentrations of various ionicand metal species. SO4

2− and NO3− are the major

constituents of PM10. SO42− levels correlate positively

with SO2, PM10, and Ca2+.The non-sea salt sulfate fractions in PM10 are

over 90% of the total sulfate at most of the sites. Theurban and semi-urban sites show evidence ofenhanced concentrations of Fe, Zn, Mn, Cd, andPb. In contrast, the rural sites have lower concen-trations of trace metal. Trace metal concentrationvaried at the urban (Nagpur), semi-urban (Kosi andDholpur), and rural sites. Aerosol chemical compo-sition expressed on the basis of the EFcrust indicates acrustal source. There is a general “uniformity ofcomposition” of the AEEs for Zn and Fe in aerosols,whereas Mn, Cu, Cd, and Pb are non-enrichedelements. NOx and SO2 show the variation from 16to 69 and 4 to 11 μg m−3, respectively, for differentsites. These background measurements may providebetter understanding about the nature and sources ofaerosols in rural and urban sites to undertakeappropriate policy measure for improvement of theambient air quality.

Acknowledgments Authors wish to thank Director NPL andlate Dr. A. P. Mitra for guidance and continuous encourage-ments. Authors thank the funding support of ISRO-GBP. Theauthors are also thankful to Dr. R. Sridharan, Dr. C.B.S. Dutt,and Dr. Shyam Lal for the organizational support during thefield campaign. The authors are thankful to Dr. Shankar G.Aggarwal, scientist, NPL, New Delhi for his editorial support.Thanks are also to the Director CRRI and Dr. A. Shukla ofCRRI Delhi for providing meteorological data of campaignroute.

References

Allen, A. G., Harrison, R. M., & Erisman, J. W. (1989). Fieldmeasurements of the dissociation of ammonium nitrate andammonium chloride aerosols. Atmospheric Environment, 23,1591–1599.

Bencs, L., Ravindra, K., De Hoog, J., Rasoazanany, E. O.,Deutsch, F., Bleux, N., et al. (2008). Mass and ioniccomposition of atmospheric fine particles over Belgiumand their relation with gaseous air pollutants. Journal ofEnvironmental Monitoring, 10, 1148–1157.

Bodhaine, B. A. (1983). Aerosol measurement at four backgroundsites. Journal of Geophysical Research, 88, 10753–10768.

Chan, Y. C., Simpson, R. W., Metainsh, G. H., Vowels, P. D.,Cohen, D. D., & Bailey, G. M. (1997). Characterization ofchemical species in PM2.5 and PM10 aerosols in Brisbane,Australia. Atmospheric Environment, 31, 3773–3785.

Cheng, Z. L., Lam, K. S., Chan, L. Y., Wang, T., & Cheng, K.K. (2000). Chemical characteristics of aerosols at coastalstation in Hong-Kong. I. Seasonal variation of major ions,halogens and mineral dust between 1995–1996. Atmo-spheric Environment, 34, 2771–2783.

Chester, R., Nimmo, M., Fones, G. R., Keyse, S., & Zhang, Z.(2000). Trace metal chemistry of particulate aerosols fromthe UK mainland coastal rim of the NE Irish Sea.Atmospheric Environment, 34, 949–958.

Cooper, J. A. (1980). Environmental impact of residential woodcombustion emissions and its implications. Journal of theAir Pollution Control Association, 8, 855–861.

Control of Urban Pollution Series (1981–1982). Inventory andassessment of pollution emission in and around Agra-Mathura region (Abridged). CUPS 7: Central PollutionControl Board, New Delhi, India.

Control of Urban Pollution Series (1987). Status of air Qualityin Agra region. CUPS 15: 192–0. Central PollutionControl Board, New Delhi, India.

Dockery, D. W., Pope, C. A., Xu, X., Spengler, J. D., Ware, J.H., Fay, M. E., et al. (1993). An association between airpollution and mortality in six US cities. The New EnglandJournal of Medicine, 329, 1753–1759.

Duce, R. A., Arimoto, R., Ray, B. J., Unni, C. K., & Harder, P.J. (1983). Atmospheric trace elements at Enewetak Atoll:1. Concentrations, sources, and temporal variability.Journal of Geophysical Research, 88(C9), 5321–5342.

Echalar, F., Gaudichet, A., Cachier, H., & Artaxo, P. (1995).Aerosol emissions by tropical forest and savannah biomassburning: characteristic trace elements and fluxes. Geo-physical Research Letters, 22, 3039–3042.

Gillet, R.W., Ayers, G.P., Ginting, N., Selleck, P., Hooper, M. &Trapper, N. (1992). Measurement of sulphur and nitrogendeposition at four sites in an area of Western Java. In Proc.2nd CAAP/IGAC/IGBPWorkshop, Bombay, 29 September–2 October.

Gupta, P. K., Khem, S., Dixit, C. K., Nahar, S., Sharma, C.,Sahai, S., et al. (2007). Spatial distribution in aerosol massand size characteristics between Delhi and Hyderabadduring land campaign in February. Indian Journal ofRadio & Space Physics, 36, 576–581.

Granat, L., Suksomsankh, K., Simachaya, S., Tabucanon, M. &Rodhe, H. (1992). Acid rain in Thailand—results from


daily precipitation chemistry measurements at two sites. InProc. 2nd CAAP/IGAC/IGBP Workshop, Bombay, 29September–2 October.

Hidy, G. M., Appel, B. R., Charlson, D. H., Smith, T. B., Suder,H., Wesdowki, J. J., et al. (1975). Summary of theCalifornia aerosol characterization experiment. Journal ofAir Pollution Control Assessment, 25, 1106–1114.

Ho, K. F., Lee, S. C., Chak, K., Chan, Yuc, J. C., Choud, J. C.,et al. (2003). Characterization of chemical species inPM2.5 and PM10 aerosols in Hong Kong. AtmosphericEnvironment, 37, 31–39.

Horemans, B., Krata, A., Buczynska, A. J., Dirtu, A. C., Meel,K., Van Grieken, R., et al. (2009). Major ionic species insize-segregated aerosols and associated gaseous pollutantsat a coastal site on the Belgian North Sea. Journal ofEnvironmental Monitoring, 11, 670–677.

Jacob, J. B., & Hocheisser, S. (1958). Continuous sampling andultra micro determination of Nitrogen Dioxide in Air.Analytical Chemistry, 30, 426–428.

Khare, P., Goel, A., Patel, D., & Behari, J. (2004). Chemicalcharacterisation of rainwater at a developing urban habitatof Northern India. Atmospheric Research, 69, 135–145.

Kleinman, M. T., Tomezyk, C., Leaderer, B. P., & Tanner, R. L.(1979). Inorganic nitrogen compounds in New York city.Air Annals of the New York Academy of Science, 322,115–123.

Koutrakis, P., Wolfson, J. M., & Spengler, J. D. (1988). Animproved method for measuring aerosol strong acidity:Results from a nine-month study in St Louis, Missouri andKingston, Tennessee. Atmospheric Environment, 22A,157–162.

Kulshrestha, U. C., Saxena, A., Kumar, N., Kumari, K. M., &Srivastava, S. S. (1995). Mass size distribution of aerosolsat a suburban site of Agra. Indian Journal of Radio andSpace Physics, 24, 178–183.

Levaggi, D. A., Kothny, E. L., Belsky, T., de Vera, E., &Mueller, P. K. (1974). Quantitative analysis of nitrogenoxides in presence of nitrogen dioxides at ambientconcentrations. Environmental Science and Technology,8, 347.

Logan, J. A. (1983). Nitrogen oxides in the troposphere: globaland regional budgets. Journal of Geophysical Research,88, 10785–10807.

Millero, F. J., & Sohn, M. L. (1992). Chemical oceanography.Boca Raton, FL: CRC. 531.

Murthy, R.S., Hirekerur, L.R., Deshpande, S.B., & RaoVenkata, B.V. (1982). Benchmark Soils of India, 105–374.

National Environmental Engineering Research Institute(NEERI), Nagpur (2000). Ambient air quality status forten cities for India. No. 8 (1995 & 1996).

Novakov, T., Chang, S. G., & Hanker, A. B. (1974). Sulfates aspollution particles: catalytic formation on carbon (soot)particles. Science, 186, 259–261.

Ohta, S., & Okita, T. (1990). A Chemical Characterisation ofatmospheric aerosols in Sapporo. Summary of the Californiaaerosol characterization experiment. Atmospheric Environ-ment, 24A, 1409–1416.

Parmar, R. S., Satsangi, G. S., Kumari, M., Lakhani, A.,Srivastava, S. S., & Prakash, S. (2001). Study of sizedistribution of atmospheric aerosol at Agra. AtmosphericEnvironment, 35, 693–702.

Peirson, D. H., Cawse, P. A., & Cambry, R. S. (1974).Chemical uniformity of airborne particulate material, anda maritime effect. Nature, 25, 675–679.

Pio, C. A., & Harrison, R. M. (1987). The equilibrium ofammonium chloride aerosol with gaseous hydrochlorideacid and ammonia under tropospheric conditions. Atmo-spheric Environment, 21A, 1243–1246.

Pueschal, R. F., Van Valin, C. C., Castillo, R. C., & Gonor, E.(1986). Aerosols in polluted versus non polluted air masses:Long range transport and effect on clouds. Journal ofClimate and Applied Meteorology, 25, 1928–1917.

Shaw, R.W. (1987). Air pollution by particles. ScientificAmerican,255, 96–103.

Tanaka, S., Komazaki, Y., Yamagata, K., & Hasimato, Y. (1987).Behaviour of ammonium chloride and ammonium nitrate inthe atmosphere. Nippon Kagaku Kaishu. 2338–2343.

Vincent, J. H. (1989). Aerosols: their generation, behaviour andapplication: (Proceedings of the Third Annual Conferenceof The Aerosol Society, March 1989). The AerosolSociety, London. Journal of Aerosol Science, 20(5), 625.

Wakamatsu, S., Utsunomiya, A., Han, J. S., Mori, A., Uno, I., &Uehara, K. (1996). Seasonal variation in atmospheric aerosolsconcentration covering northern Kyushes, Japan and Seoul,Korea. Atmospheric Environment, 30, 2343–2354.

Weatherburn, M. W. (1967). Phenol hypochlorite reaction fordetermination of ammonia. Analytical Chemistry, 39, 971–974.

West, P. W., & Gaeke, C. C. (1956). Fixation of sulphur dioxideas sulfitomercurate III and subsequent colorimetric deter-mination. Analytical Chemistry, 28, 1816–1819.

Wojicik, G. S., & Chang, J. S. (1997). A re-evaluation of sulfurbudgets, lifetimes, and scavenging ratios for Eastern NorthAmerica. Journal of atmospheric Chemistry, 26, 109–145.


Chemical Characteristics of Aerosols and Trace Gas

Documents

Transcript of Chemical Characteristics of Aerosols and Trace Gas