Chemical composition of waste burning organic aerosols at landfill and urban sites in Delhi

Journal Pre-proof Chemical Composition of Waste Burning Organic Aerosols at Landfill and Urban Sites in Delhi Rishu Agarwal, Kritika Shukla, Sudhanshu Kumar, Shankar G. Aggarwal, Kimitaka Kawamura PII:

S1309-1042(19)30515-X

DOI:

https://doi.org/10.1016/j.apr.2019.12.004

Reference:

APR 701

To appear in:

Atmospheric Pollution Research

Received Date: 25 August 2019 Revised Date:

4 December 2019

Accepted Date: 4 December 2019

Please cite this article as: Agarwal, R., Shukla, K., Kumar, S., Aggarwal, S.G., Kawamura, K., Chemical Composition of Waste Burning Organic Aerosols at Landfill and Urban Sites in Delhi, Atmospheric Pollution Research, https://doi.org/10.1016/j.apr.2019.12.004. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Turkish National Committee for Air Pollution Research and Control. Production and hosting by Elsevier B.V. All rights reserved.

1 2

Highlights: •

The organic chemical characteristics of waste burning aerosols from a landfill and an urban site of Delhi are studied

3 4

•

Fatty acids were found to be the most abundant class at both the sites

5

•

However, at urban site fatty acids and sugars were found to be contributing equally to the total organic compounds

6 7

•

and landfill site, respectively.

8 9 10

Levoglucosan and C18:0 fatty acid was found to be most abundant compounds at urban

•

Lignin and resin products, except 4-hydrobenzoic acid are first time reported to be released

from

open

waste

burning

activities

in

the

present

study.

11

Chemical Composition of Waste Burning Organic Aerosols at Landfill and Urban Sites in

12

Delhi

13

Rishu Agarwal1,2, Kritika Shukla1,2, Sudhanshu Kumar2,3, Shankar G. Aggarwal1,2*, Kimitaka

14

Kawamura4

15

1

16

Campus, Dr. K.S. Krishnan Marg, New Delhi, 110012

17

2

18

Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110012

19

3

now at Indian Institute of Technology (IIT), New Delhi 110016

20

4

Chubu Institute for Advanced Studies, Chubu University, 1200 Matsumato-cho, Kasugai 487-

21

850, Japan

22

*

Academy of Scientific & Innovative Research (AcSIR), CSIR-National Physical Laboratory

Gas Metrology, Environmental Sciences & Biomedical Metrology Division, CSIR-National

Correspondence

at

[email protected]

1

23

Abstract

24

Organic composition of total suspended particles collected from an open waste burning landfill

25

site and an urban site of Delhi, one of the most populated cities of Asia was studied. Among the

26

organic compounds detected, fatty acids were found to be the most abundant class of compounds

27

at both the sites, urban (16823 ng m-3) as well as landfill site (1218120 ng m-3). As a single

28

compound detected (on average), levoglucosan (2925 ng m-3) was found to be most abundant at

29

urban site, whereas C18:0 fatty acid (76090 ng m-3) dominated at the landfill site. Levoglucosan

30

contributed up to 87% of total identified sugars at urban and 86% at landfill site, suggesting

31

biomass burning to be one of the major contributors of sugar compounds, and a possible

32

influence of landfill waste burning on urban aerosols. CPI value for n-alkanes was close to unity

33

at both sites (0.81 at landfill and 1.27 at urban site) indicating the anthropogenic nature of the

34

aerosols. A predominance of tere-phthalic acid (42555 ng m-3) was found in aerosol samples

35

collected at landfill site because of plastic enriched waste burning activity. Except 4-

36

hydroxybenzoic acid, all other lignin and resin products are first time reported to be released by

37

open waste burning activities in the present study. We also found a strong positive correlation

38

between di-isobutyl phthalate and di-n-butyl phthalate at both urban (r2=0.94) and landfill site

39

(r2=0.86), suggesting them to be the commonly used plasticizers, and plastics to be a main

40

constituent of municipal waste. Since, the waste burning at landfill sites is a common practice

41

either to reduce waste heaps or be it a self-ignited burning leading to significant emissions, we

42

report the chemical composition of organic aerosols originating from such emissions. The

43

information presented in this paper may further be useful in estimating the contribution of

44

municipal waste burning aerosols on urban burden of particulate matter.

45

Keywords:

Organic

aerosols,

landfill,

municipal

2

waste

burning,

urban

aerosols

46

1. Introduction

47

Air pollution is one of the major causes of deteriorating environmental and human health

48

especially in the urban areas. The varied chemical composition of aerosols depends on the source

49

of emission which includes fuel burning, vehicular exhausts, power plants, open waste burning,

50

construction works, etc. in urban areas. Additionally, fuel combustion during household cooking

51

has also been reported as an important source of particulate emissions (Pervez et al., 2019). The

52

urban aerosols are considered to represent a mixture of aerosols comprising of emissions from

53

the different local sources and long-range transports also during unusual weather events. Open

54

waste burning is one of the important sources of toxic aerosols originating in a city environment.

55

Globally, the municipal solid waste generation has increased from 0.68 billion tons per year in

56

2002 (Hoornweg and Bhada-Tata, 2012) to 2.01 billion tons in 2016 and is projected to rise up to

57

3.40 billion tons per year by 2050 according to the World Bank (Kaza et al., 2018).

58

The common municipal waste management cycle and practices include collection, recycling,

59

composting, land filling/dumping, and incineration/burning (Weidinmyer et al., 2014). However,

60

either burnings of waste in open at small scales or dumping in the landfill site are the two most

61

usual and cheaper solutions used in the developing countries. An estimated 41% of the total

62

waste generated annually around the world is treated by open burning (Weidinmyer et al., 2014).

63

Only a small fraction of it is segregated and treated in incinerators or recycled. Controlled

64

burning (incineration) or waste to energy practices are common in developed countries as the

65

waste generated contains a large fraction of dry combustible materials such as paper. In

66

developing countries, the municipal waste generated contains more of wet organic waste which

67

makes it unsuitable for incineration. Since such facilities including proper segregation and waste

68

to energy are limited in developing countries, most of the waste finds its destination in landfill.

69

Non-availability of environment-friendly technologies and initiatives for disposal of waste is one

70

of the major causes of the rising landfill heaps in the urban areas. The urban waste has a greater

71

contribution from plastics/polyethenes, e-waste, packaging materials (juice and milk cartons),

72

styrofoam materials used in single-use cutlery, fabrics, metals, kitchen waste, garden waste,

73

papers, etc. Since this mixed waste contains combustible material, the waste at landfill sites often

74

catches fire easily unintentionally and sometimes are burn deliberately to reduce the waste heaps.

3

75

The waste materials like plastics and e-wastes on burning emit toxic and hazardous fumes which

76

could prove detrimental if inhaled in large quantities.

77

The open burning of waste leads to emission of various air pollutants such as greenhouse gases,

78

trace gases, particulate matter and other toxic compounds (Weidinmyer et al., 2014). The type of

79

emissions depends on the burning conditions such as temperature, environment, location and

80

mostly on the composition of waste that is being burnt. PM10, PM2.5 and organic carbon (OC)

81

emissions from open waste burning have been estimated to account for 24%, 29% and 43% of

82

the total anthropogenic emissions of PM10, PM2.5 and OC respectively per year globally

83

(Weidinmyer et al., 2014). Open waste burning has been reported as an evident source of PM2.5

84

and toxic metals in urban areas in various studies. In Mexico City, garbage burning contributes

85

3-30% of PM2.5 mass (Li et al., 2012). Hodzic et al. (2012) in another study on Mexico City

86

reported an elevation of 40-80% in organic aerosols emission levels during trash burning

87

activities and estimated a reduction in organic aerosols emission and PM2.5 levels by 2-40% and

88

1-15%, respectively on mitigation of such activities. Based on the observed concentrations of

89

metals such as tin (Sn) and antimony (Sb) (proposed tracers of municipal waste burning

90

emissions) and lead (Pb) isotopic ratios, Kumar et al. (2018) reported an influence of open waste

91

burning emissions on urban aerosols in the city of Delhi. In the same study, open waste burning

92

is suggested to be one of the sources of chromium (Cr) and Cr (VI) in urban aerosols. Total

93

carbon (TC) has also been reported as the most abundant component of PM2.5 (Bano et al., 2018)

94

and PM10-2.5 mass (Matawle et al., 2014) from municipal waste burning activities in the urban

95

city of Raipur (India). Owing to the presence of such toxic species, the particulate matter

96

emissions has been associated with several short term (aggravation of asthma, shortness of

97

breath, chest pains) and long-term (circulatory, respiratory and pulmonary diseases) health risks.

98

Spontaneous and auto ignition of fires besides deliberate burning of waste are a common

99

phenomenon at landfill sites possibly because of exothermic biological and chemical reactions

100

taking place in the degrading waste and presence of combustible materials. Due to the extent of

101

such emissions, open waste burning at landfill sites has been included in the emission inventories

102

recently (Weidenmyer et al., 2014, Gargava et al., 2014). Although some of the studies have

103

reported inorganic characteristics and specific metal tracers (Kumar et al., 2015; Kumar et al.,

104

2018) for the open waste burning, a limited number of studies have been carried out to 4

105

understand few of the organic characteristics (such as OC, EC and plastic burning tracers) (Bano

106

et al., 2018; Downard et al., 2015; Kawamura and Pavuluri, 2010; Simoneit et al., 2005) of the

107

aerosols generated from municipal waste burning at landfills. However, no significant data is

108

available for organic speciation of the particulate matter emitted from open burning of municipal

109

waste at landfill sites. The present study provides an account of chemical composition of the

110

organic aerosols generated at a landfill site in the metropolitan city Delhi due to waste burning

111

activities and an urban site. Here we report the chemical composition of aerosol types which is

112

based on a limited number of samples collected in different seasons. This information may be

113

important to estimate the contribution of open waste burning towards the burden of particulate

114

matter in urban areas.

115

2. Methodology

116

2.1 Sampling

117

TSP (Total Suspended Particulate Matter) samples were collected from two different locations,

118

i.e., a landfill site, and an urban site in Delhi. The landfill site samples were collected from the

119

Okhla landfill in Delhi. The waste disposal started in 1994 at this site. The landfill has

120

approximately 5.6 million tonnes of waste in place. The existing landfill covers a total of 54

121

acres, which is almost completely covered with waste. These samples accounted for source

122

specific aerosol samples of open waste burning. Sampling was carried out on prebaked (at 450˚

123

C for 6 hours) quartz filters (Pallflex 2500QAT-UP, 8 inch × 10 inch) using a high-volume

124

sampler (Vayubodhan Upkaran Pvt. Ltd.) at a flow rate of ̴ 1100 l min-1 at both the sites. At

125

Okhla landfill site, the sampler was placed downwind to the waste burning site and run on an

126

hourly duration during the daytime in October 2014 (n=7). The urban samples were collected at

127

the rooftop of CSIR-National Physical Laboratory (NPL) building in December 2011. The

128

samples at NPL site were collected on a 12-hourly basis, daytime starting from ̴7:00 to 19:00 and

129

nighttime from ̴ 19:00 to 7:00 (n=5).

130

2.2 Chemical Analyses

131

The samples were analyzed to study the source specific chemical composition of the aerosols.

132

OC, WSOC, n-alkanes, aromatic acids, fatty acids, SOA tracers, sugars, phthalates, polyacids,

133

sterols and lignin and resin products were determined in the samples. The organic carbon was 5

134

measured using the thermal optical method following the Interagency Monitoring of Protected

135

Visual Environments (IMPROVE) protocol. The carbonate carbon was assumed to be negligible.

136

A punch of 1.4 cm diameter from sample filter was placed in a quartz tube inside the thermal

137

desorption chamber of semi-continuous Carbon Analyzer (Sunset Laboratory Inc. Model 4L)

138

(Agarwal et al., 2010). The analytical errors (reproducibility) were estimated to be within 9% by

139

the analyses of different punch cuts (n=3) of the same filter samples.

140

For the determination of WSOC, a disc of 2 cm diameter was taken from sample filter and

141

extracted using ultrasonic bath for 30 min with 7 ml of Milli-Q water in a glass bottle. This was

142

followed by filtration using disc filters to remove particles from the extract. 0.1 ml of 2 M HCl

143

solution was added to 5 ml of the filtered extract. After purging for 10 min with ultrapure air (80

144

ml min-1), 100 µl of the solution was injected into the TOC analyzer (Shimadzu TOC-5000A)

145

(Agarwal et al., 2010). Duplicate analyses were performed to estimate analytical errors

146

(repeatability) and it was found to be within 6%.

147

For analysis of organic compounds, a filter aliquot of approximately 10 cm2 was extracted with

148

dichloromethane/methanol (2:1, v/v) thrice using ultrasonication bath for 30 min. The solvent

149

extracts were filtered through quartz wool, concentrated using rotary evaporator and blow dried

150

with pure nitrogen gas. The extracts were then reacted with 50 µl of N,O-bis

151

(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylsilyl chloride and 10 µl of pyridine

152

as catalyst at 70˚C for 3 h to derive trimethylsilyl derivatives. Field blank filters were treated the

153

similar way for quality assurance. The derivatized total extracts were analyzed using Gas

154

Chromatography-Mass Spectrometry (GC-MS) (HP GC 6890, MSD 5973) (Agarwal et al., 2010;

155

Fu et al., 2008). The GC separation was achieved on a DB-5MS fused silica capillary column

156

(30 m x 0.25 mm i.d., 0.5 mm film thickness). The mass spectrometer was operated on the

157

electron impact (EI) mode at 70 eV and scanned from 50 to 650 Da. Mass spectral data were

158

acquired and processed with the Chemstation software. Individual compounds were identified by

159

comparing mass spectra with those of literature and library data and authentic standards and by

160

interpretation of mass fragmentation patterns. The data reported in this study is corrected for

161

field blanks.

162

3. Results and Discussion

6

163

3.1 Mass, WSOC and OC Concentration

164

The mass concentration of particulate matter (TSP) during the sampling period at the urban site

165

ranged from 508-979 µg m-3 (average 724 µg m-3) and 1297-8242 µg m-3 (3780 µg m-3) at the

166

landfill site (Table 1). The mass concentration was much higher at the landfill site than at the

167

urban site as the landfill samples were collected in the vicinity of the open waste burning

168

emissions.

169

Organic carbon (OC) is a major constituent of the atmospheric aerosols and is emitted either

170

directly in particulate form or formed through gas-to-particle phase conversion in the atmosphere

171

(Timonen et al., 2008). Majority of the organic matter present in atmospheric aerosols is water-

172

soluble, typically accounting for 10-70% (Jalfrezzo, 2005). WSOC affects the ability of aerosols

173

to form cloud condensation nuclei which is important for the Earth’s radiative budget (Timonen

174

et al., 2008). At the landfill site, the OC concentration was found to be in the range of 418-6327

175

µg C m-3 (2538 µg C m-3), much higher than at the urban site (62-190 µg C m-3, average 141 µg

176

C m-3). OC contributed ̴ 62% and ̴ 19% to TSP mass at the landfill and urban site, respectively.

177

The concentration of WSOC ranged from 39.27-570 µg C m-3 (228.96 µg C m-3) at the landfill

178

site and 19.98-54.02 µg C m-3 (35.36 µg C m-3) at the urban site. The average mass concentration

179

ratios of WSOC and OC are 0.09 at landfill site and 0.26 at urban site. The WSOC/OC ratio has

180

been used to infer the extent of aging of aerosols in the atmosphere. Freshly emitted aerosols

181

exhibit lower WSOC/OC ratio whereas a higher ratio indicates substantial aging of the aerosols

182

suggesting long range transport or limited atmospheric mixing of aerosols as is evident by the

183

difference in the urban and landfill site aerosols in the present study. WSOC and OC showed a

184

strong linear relationship at the landfill site (r2=0.97), suggesting a common source whereas at

185

urban site they were found to be fairly correlated (r2=0.61), indicating influence of different

186

sources and atmospheric processing pathways (Aggarwal and Kawamura, 2009). The reported

187

WSOC/OC ratio at urban site in this study was found to be similar to that reported from other

188

Indian cities viz., Kanpur (0.21-0.65) (Ram et al., 2012) and Mumbai (0.36) (Aggarwal et al.,

189

2013), lower than that reported from Kathmandu (0.50) (Shakya et al., 2010), paddy and wheat

190

residue burning (0.52 and 0.60) in Patiala (Rajput et al., 2014) and urban aerosols of Helsinki

191

(0.54) (Timonen et al., 2007). The WSOC/OC ratio is first time being observed and reported for

7

192

the aerosols originating from open burning of mixed municipal waste at the landfill site in the

193

present study.

194

3.2 Organic Species

195

Nine categories of organic compounds were detected in the collected samples including sugars,

196

alkanes, phthalates, lignin products, fatty acids, sterols, polyacids, aromatic acids, and some

197

biogenic secondary organic aerosol tracer compounds. Concentration of total organic compounds

198

was found to be higher at the landfill site (2456250 ng m-3) than the urban site (50330 ng m-3).

199

Among the organic compounds detected, fatty acids are found to be the most abundant class of

200

compounds at both the sites; urban (16823 ng m-3) as well as landfill site (1218120 ng m-3)

201

similar to another study by Fu et al. (2009) in urban tropical Indian region where fatty acids and

202

phthalates were found to be the highest contributing compound class. However, similar studies

203

carried out in mountainous (Fu et al., 2008) and marine regions (Fu et al., 2013) have found

204

sugars to be the dominant compound class. At the urban site, fatty acids (33.43%) and sugars

205

(33.20%) contribute almost equally to the total organic compound concentration (Figure 1). As a

206

single compound detected (on average), levoglucosan (2925 ng m-3) was found to be most

207

abundant at urban site, whereas C18:0 fatty acid (76090 ng m-3) dominated at the landfill site. The

208

mass concentrations of all the detected compounds are given in Table 2.

209

Total organic compounds identified in the open waste burning aerosols from landfill site

210

accounted for 4.28-12.04% (average 9.45%) of OC similar to that observed in tropical Indian

211

aerosols (9.35%) by Fu et al. (2009) whereas at urban site it ranged from 3.26-5.79% (average

212

4.52%) much lower than that reported by Fu et al. (2009). As a class of compounds, fatty acids

213

have a major contribution towards OC at both the urban site (1.87%) and the landfill site (3.96%)

214

(Table 3). In case of WSOC, sugars contributed the most to WSOC at urban site (4.21%) and n-

215

alkanes at the landfill site (29.81%).

216 217

3.2.1 n-alkanes

218

The mass concentration of n-alkanes (C16-C36) varied widely among the open-waste burning

219

aerosols and urban aerosols. The variation indicates towards the different sources of contribution

220

to the poor air quality. Also, the distribution of n-alkanes is influenced and determined by the

221

relative contribution from biogenic and anthropogenic sources (Li et al., 2010). C16-C36 8

222

homologous n-alkanes were detected in the landfill site whereas C20-C36 homologues were

223

detected at urban site with a total of 637042 ng m-3 and 4283 ng m-3, respectively (Figure 2).

224

Overall, higher concentrations are reported at the landfill site clearly due to the open waste

225

burning activities. Low molecular weight odd numbered n-alkanes (C17-C23) were not detected at

226

either site. The even numbered low molecular weight n-alkanes (C16-C18) find its source in the

227

incomplete combustion of fossil fuels (Fu et al., 2010). However, the chemical characteristics

228

show the absence of petrogenic source signature n-alkanes at urban site which possibly is due to

229

the lesser vehicular activity around the site on sampling days. Also, n-alkanes lower than C20

230

with even carbon number predominance have been reported to be arising from microbial

231

activities (Li et al., 2010), which clearly explains the absence and presence of this range at urban

232

and landfill site, respectively. n-alkanes with even number predominance in the range of C16-C28

233

have been reported to be originating from refuse burning especially plastics (Fu et al., 2010;

234

Simoneit et al., 2005). The presence of these in high concentrations at landfill site confirms the

235

source to be refuse plastic burning at the site. The high molecular weight alkanes (C29-C33) with

236

odd numbered predominance and Cmax at C31 find its source in the higher plant waxes resulting

237

from abrasion of leaf epicuticular waxes (Fu et al., 2010; Kalaitzoglou et al., 2004; Simoneit et

238

al., 2004). Also, the decaying plant organic matter in soils can become airborne in windy

239

conditions and be transported by winds (Schefuß et al., 2003). Besides these high molecular

240

weight alkanes, the landfill site samples show an additional characteristic feature of presence of

241

C34-C36 alkanes in high concentrations as compared to the urban site. The long chain alkanes

242

from C34 to > C37 are attributed to high molecular weight paraffin wax, used to coat the inner

243

surfaces of food packagings; e.g. milk and juice cartons (Fu et al., 2010; Simoneit et al., 2004).

244

This evidently suggests the open burning of municipal waste in bulk to be the major source of n-

245

alkanes at landfill site aerosols. The presence of such alkanes in urban samples even in small

246

quantities indicates that urban aerosols are influenced with such open-burning practices in Delhi.

247

The Carbon Preference Index (CPI) is the ratio of odd-carbon to even-carbon number n-alkanes

248

used to identify their sources. n-alkanes with CPI greater than 5 are believed to have originated

249

from higher plant waxes whereas, the aerosols originating from anthropogenic sources have a

250

CPI of close to unity (Kang et al., 2016). In the present study, the CPI values of n-alkanes (C16-

251

C36) in urban (CPI=1.27) as well as landfill (CPI=0.81) site samples are close to unity, proving

252

the source to be anthropogenic. Similar CPI values have been observed in other studies such as 9

253

from tropical Indian aerosols of Chennai (1.56 for winter and 1.52 in summer) (Fu et al., 2010), a

254

range of 1.63-2.41 from areas around the coal-based power plants in western Greece

255

(Kalaitzoglou et al., 2004), 1.08 from urban atmosphere of Guangzhou city in China by Bi et al.

256

(2003) and 1.7 from Algiers metropolitan city (Yasssa et al., 2001). Yassaa et al. (2001) reported

257

a CPI value of 1.1 (C24-C32) from a site 50 m away from a landfill (Oued Smar) in Algiers which

258

is consistent with values determined in this study. CPI values reported in this study are much

259

lower than those observed in forest areas of Mt. Tai in Japan (4.42 in daytime and 4.63 in

260

nighttime) by Fu et al. (2008).

261

3.2.2 Aromatic acids

262

Four aromatic acids, i.e., benzoic acid and three phthalic acids (o-, m-, and p-isomers), were

263

detected in the urban aerosol samples (Figure 3). The total concentration of aromatic acids was

264

3934 ng m-3 at urban site and 308909 ng m-3 at landfill site. The concentration of benzoic acid

265

ranged from 9.7-26 ng m-3 at urban site and 71-5726 ng m-3 at landfill site. These values are

266

much higher to those reported in urban organic aerosol in tropical India (0.54±2.16 ng m−3 in

267

winter) (Fu et al., 2010). The relatively low concentrations of benzoic acid in comparison to total

268

phthalic acid in urban aerosols may be explained by their presence in gas phase rather in

269

particulate phase. Benzoic acid is proposed to be a primary pollutant from the exhaust of motor

270

vehicles (Kawamura and Kaplan, 1987; Kawamura et al., 2000; Rogge et al., 1993) and a

271

secondary product from photochemical degradation of aromatic hydrocarbons such as toluene

272

emitted by automobiles (Suh et al., 2003).

273

The concentration ranges of total phthalic acids were 3.84-1166 ng m-3 at urban and up to 67856

274

ng m-3 at landfill site. Their concentrations are higher than those reported from aircraft aerosols

275

over China (17±13 ng m-3 in summer) (Wang et al., 2007) and over the northwestern Pacific

276

(average 1.5 ng m-3) (Simoneit et al., 2004b). Some reported sources of phthalic acids in

277

atmospheric particles are the waste burning emissions, fossil fuel combustion (primary source)

278

and the secondary formation by oxidation of precursor species emitted during anthropogenic

279

activities (Kumar et al., 2015). Referring to previous studies (Fu et al., 2010; Jung et al., 2010;

280

Kawamura and Pavuluri, 2010; Kumar et al., 2015, Li et al., 2019), we have found

281

predominance of tere-phthalic acid (42555 ng m-3) in aerosol samples collected at landfill site

282

because of plastic enriched waste burning activity. However, such a feature of presence of tere10

283

phthalic acid was not observed at urban site (635 ng m-3). High abundances of tere-phthalic acid

284

have also been reported in ambient aerosols because of plastic-waste burnings and other

285

anthropogenic emissions (Fu et al., 2010; Kumar et al., 2015; Li et al., 2019; Mkoma and

286

Kawamura, 2013). The molecular distribution of phthalic acids was characterized by a

287

predominance of tere-phthalic acid followed by benzoic acid at landfill site, being similar to

288

those reported in the aircraft aerosols over China (Wang et al., 2007) and East China Sea

289

(Simoneit et al., 2004b). Phthalic acids have been proposed as SOA products that can be used as

290

a surrogate for the contributions of SOA to an ambient sample (Oliveira et al., 2007). In our

291

study, WSOC/OC ratios are higher in urban aerosols suggesting urban aerosols to be more

292

photochemically processed, which supports the secondary pathways for formation of phthalic

293

acids. Fu et al. (2008) showed strong negative correlation (r2=0.62) between phthalic acids and

294

phthalate esters in nighttime and no correlation was found in daytime (r2=0.10) organic aerosols

295

over Mt. Tai in North China. Contrast to this, in our study positive but weaker correlation was

296

found between phthalic acids and phthalate esters at urban site (r2=0.32), while no correlation

297

was found in landfill samples (r2=0.09). The weak or no correlation between these two

298

compounds indicates that they have different sources. Phthalate esters may be emitted by burning

299

of plastic materials at landfill site whereas phthalic acid may be produced by the photochemical

300

oxidation of aromatic hydrocarbons in the atmosphere.

301

3.2.3 Fatty Acids

302

A homologous series of saturated straight chain fatty acids (C12:0–C32:0) and unsaturated fatty

303

acids (C16:1, C18:1 and C22:1) were detected in the aerosol samples. Concentration ranges of total

304

fatty acids were 8.6-964 ng m-3 at urban site and up to 368992 ng m-3 at landfill site of Delhi.

305

Fatty acids with even carbon-number predominance were detected at urban site with a peak at

306

palmitic acid (C16:0) (Figure 4), indicating a significant emission of lipid class compounds from

307

biological sources (Lechevalier, 1977; Simoneit, 1988). A similar bimodal distribution has been

308

reported in continental (Simoneit and Mazurek, 1982; Wang and Kawamura, 2005) and marine

309

aerosols (Kawamura et al., 2003; Mochida et al., 2002). The high concentration of palmitic acid

310

at urban site is similar to that found in studies done in wet season of Tanzania, East Africa

311

(Mkoma and Kawamura, 2013) and in Guiyang city, Southwest China (Li et al., 2019). Similar

312

feature of even carbon number fatty acids was detected at landfill site, but odd carbon number

11

313

fatty acids were absent. However, the concentration of even carbon number fatty acids was much

314

higher than that at urban site.

315

The concentration ratios of lower molecular weight fatty acids (LFAs,
316

molecular weight fatty acids (HFAs, C20:0-C32:0) were 0.46±0.13 at urban site versus 29.1±17.7 at

317

landfill site. These values at landfill site are higher to those reported in Mt. Tai aerosols

318

(1.02±0.80) in Central East China (Fu et al., 2008) while urban site values are comparable. HFAs

319

are derived from terrestrial higher plant wax whereas LFAs have multiple sources such as

320

vascular plants, marine phytoplankton, microbes and kitchen emissions (Kolattukudy, 1976;

321

Rogge et al., 1991; Schauer et al., 2001). Some longer-chain fatty acids, heneicosanoic (C21:0),

322

tricosanoic acid (C23:0) nonacosanoic acid (C29:0) and dotriacontanoic (C32:0) acid which are

323

specific to terrestrial higher plants (Kawamura et al., 2003), were not detected at landfill site.

324

Thus, our results suggest that lower molecular weight fatty acids are emitted from vegetation and

325

household waste being dumped and burnt at landfill site.

326

Unsaturated fatty acids are derived from biogenic sources such as higher plants but in urban

327

environments, cooking, motor vehicles and biomass burning can also be the major anthropogenic

328

sources of these acids (Rogge et al., 1993). These acids degrade rapidly once emitted to the

329

atmosphere via photochemical oxidation of double bonds as they are more reactive towards OH,

330

NO3 radicals and ozone. Palmitoleic (C16:1), oleic (C18:1) and erucic (C22:1) acids were detected

331

only at urban site. The ratio of oleic acid to stearic acid (C18:1/C18:0) at urban site ranged from

332

0.2-1.02 (average 0.34) and at landfill site ranged from 0-1.4 (average 0.59) which are higher to

333

the ratios reported in urban aerosols of Chennai (0.04-0.35) during summer at nighttime (Fu et

334

al., 2010). C18:1 was often non-detectable at landfill site, indicating its quick degradation.

335

In the present study, the ratio of unsaturated fatty acids (C16:1+C18:1) to saturated fatty acids

336

(C16:0+C18:0) were 0.11±0.12 at urban site and 0.22±0.22 at landfill site which are lower than

337

those reported by Wang et al., (2006) in Chinese megacities (1.14±0.98 in winter versus

338

0.43±0.09 in summer), indicating the photooxidation of unsaturated fatty acids at urban as well

339

as landfill site. Though the aerosols at landfill site are freshly emitted, the absence of unsaturated

340

fatty acids can be attributed to their rapid oxidation accelerated by high temperature condition at

341

burning site.

342

3.2.4 Lignin and resin products 12

343

Three lignin products (4-hydroxybenzoic acid, vanillic and syringic acid) and one resin product

344

(dehydroabietic acid) were detected in the urban and landfill site samples. Concentration of

345

lignin and resin products ranged from 21.2-196 ng m-3 at urban site and up to1515 ng m-3 at

346

landfill site (Figure 5). These values are much higher to those reported in Chinese urban aerosols

347

(1.3-53 ng m-3 in summer) (Wang et al., 2006) and urban organic aerosol in tropical India

348

(19.3±11.2 ng m−3 in winter and 12.3±3.49 ng m-3 in summer) (Fu et al., 2010). The higher

349

concentration at landfill site is due to abundance of vegetation and household garbage in the

350

mixed waste dumped at the site. Dominant species among lignins was 4- Hydroxybenzoic acid

351

(100.10 ng m−3 at urban site and 811.21 ng m−3 at landfill site), indicating the burning of plastic

352

(Simoneit et al., 2005). Resin product (dehydroabietic acid) is the second dominant species at

353

landfill site which is produced by pyrolytic dehydration of abietic acid found abundantly in pine

354

resin. Thus, leading to its usage as more specific marker of biomass burning of pine trees

355

(Simoneit et al., 1993). Vanillic acid is a source specific tracer for conifers. Vanillic and syringic

356

acid are also detectable in pine wood smoke (Simoneit, 2002). These lignin and resin derived

357

organic acids have been reported in the continental aerosols (Fu et al., 2008) and in the smoke

358

particles from biomass burning (Simoneit, 2002). Except 4-Hydroxybenzoic acid, all other lignin

359

and resin products are first time reported to be released by open waste burning activities in the

360

present study.

361

3.2.5 Phthalate Esters

362

Phthalate esters are used as plasticizers in synthetic polymers and softener in polyvinylchloride.

363

They can be released in the atmosphere on being burned from the molecular matrix by

364

evaporation because they are chemically bonded to the polymer. Three phthalates were detected

365

in this study i.e., diisobutyl (DiBP), di-n-butyl (DnBP), and di-2-ethylhexyl (DEHP) phthalates.

366

The concentration of phthalates was 15.25-994.81 ng m-3 at urban and 200-42671 ng m-3 at

367

landfill site (Figure 6). Fu et al. (2008) also reported similar concentration of phthalates at Mt.

368

Tai, North China Plain (9.83-985 ng m-3 in summer). DEHP is reported highest at landfill site

369

(14195 ng m-3). It is one of the most common plasticizers used in plastic materials and in India

370

plastics form a major portion of the municipal solid wastes being disposed into open landfills.

371

Therefore, fresh aerosols at landfill site show abundance of DEHP because of plastic-waste

372

burnings. DiBP was the dominant species in this group at urban site followed by DEHP and

13

373

DnBP. Referring to previous study (Fu et al., 2008), and especially in this study, we found a

374

strong positive correlation between DiBP and DnBP at both urban (r2=0.94) and landfill site

375

(r2=0.86), suggesting that DiBP and DnBP are commonly used plasticizers in India and emitted

376

into the atmosphere in a similar way. However, the correlation coefficient at landfill site is much

377

higher than at urban site, suggesting that they may have different processes and lifetime in the

378

atmosphere.

379

3.2.6 Poly-acids

380

Two hydroxy acids (glyceric and malic acid) were detected from the urban and landfill sites. The

381

concentration of these polyacids was found to be higher at the urban site with a total of 1278.63

382

ng m-3 than the landfill site with a total of 881 ng m-3 (Figure 7). Glyceric acid is the most

383

abundant hydroxy acid in both the samples, urban as well as landfill with an average of 200 and

384

75 ng m-3 respectively which is many folds higher than that observed in other studies (Claeys et

385

al., 2004; Fu et al., 2010). The two acids alongwith tartaric acid have been reported as the

386

secondary photooxidation products of organic precursors (Fu et al., 2010). Also, diurnal patterns

387

have been observed by Claeys et al. (2004) and Fu et al. (2010) with higher concentrations

388

during daytime confirming photooxidation to be the major source. Since the landfill samples are

389

dominated by the fresh burning aerosols, these secondary compounds ought to be in smaller

390

concentrations, as is evident in our results. Malic acid and tartaric acid have also been reported

391

from Amazonian forest aerosols (Claeys et al., 2004). The presence of malic acid in urban

392

aerosols in appreciable concentrations could be due to the proximity of the sampling site to the

393

green area. Malic acid could be produced in the atmosphere through photooxidation of succinic

394

acid (Fu et al., 2010). Also, malic acid has been proposed to be a late product in photochemistry

395

of unsaturated fatty acids (Claeys et al., 2004).

396

3.2.7 Biogenic secondary organic aerosols tracers

397

2-methyl glyceric acid, three C5 alkene triols (cis-2-methyl-1,3,4-trihydroxy-1-butene, 3-methyl-

398

2,3,4-trihydroxy-1-butene

399

methyltetrols (2-methylthreitol and 2-methylerythritol) were detected in the present study with

400

an average of 489.88 ng m-3 at urban and 1042 ng m-3 at landfill site (Figure 8). The C5 triols

401

were found to be absent in the landfill site aerosols. These compounds are tracers for isoprene

402

and monoterpene oxidation products in the aerosols. Isoprene is reported to represent almost

and

trans-2-methyl-1,3,4-trihydroxy-1-butene)

14

and

two

2-

403

50% of all the biogenic non-methane hydrocarbons worldwide (Guenther et al., 1995) and its

404

global emission is estimated to be 400-600 Tg C (Guenther et al., 2006). It is a biogenic VOC

405

released from vegetation and is highly unstable and susceptible owing to the C=C bond. It reacts

406

with oxidants (OH, O3 and NO3) present in atmosphere to form secondary organic aerosols

407

contributing to the organic loading in the atmosphere (Fu et al., 2010).

408

The two 2-methyltetrols were first time proposed as the condensable photooxidation products of

409

isoprene in atmosphere by Claeys et al. (2004). The concentration of 2-methylthreitol and 2-

410

methylerythritol ranged from 1.93-3.04 ng m-3 (average 1.88 ng m-3) and 5.12-6.87 ng m-3

411

(average 6.16 ng m-3) at the urban site respectively. In the landfill site samples 2-methylthreitol

412

was found in only one of the samples (1.71 ng m-3) whereas 2-methylerythritol was found with

413

an average of 8.29 ng m-3. These values are higher than those reported from Arctic ocean

414

aerosols (Fu et al., 2013) and urban aerosols (Fu et al., 2010) and lower than those reported from

415

Amazon forest area (Claeys et al., 2004). A strong correlation was found between the two

416

methyltetrols (r2=0.98) at the urban site, suggesting a similar pathway of formation. However, no

417

correlation was found between these two compounds at the landfill site.

418

The C5-alkene triols, which are also reported as photooxidation products of isoprene were

419

detected only in few of the samples of the urban aerosols and were absent in the landfill aerosols

420

suggesting the mechanisms of formation of these compounds to be absent at the sampling sites

421

and eliminating the waste burning to be a source of these compounds in the atmosphere, further

422

confirming the biogenic nature of these compounds. In earlier studies, methyltetrols and C5

423

alkene triols have been found in comparable concentrations and shown to follow a similar pattern

424

(Fu et al., 2010).

425

However, in the present study, no such pattern was observed. This can be explained by the fact

426

that despite being originating from one precursor (isoprene), the pathways of formation of these

427

two compound classes in the atmosphere are different.

428

It has been reported that the diepoxy derivates of isoprene can be converted into 2- methyltetrols

429

by acid-catalyzed hydrolysis reactions (Fu et al.,2010; Wang et al., 2005). C5 alkene triols are

430

formed through a set of rearrangement reactions of hydoxyperoxy radicals originating from

431

initial phase photooxidation of isoprene (Fu et al., 2010; Surrat et al., 2006). Methacrolein and

432

methyl-acreleic acid are two gas phase compounds resulting from the photooxidation of isoprene 15

433

which can further be oxidized leading to the formation of 2- methylglyceric acid (Claeys et al.,

434

2004, Fu et al., 2010).

435

2-Methylglyceric acid was found to be the most abundant SOA tracer of isoprene in the present

436

study with concentration ranging from 6.92-84.11 ng m-3 (average 21.92 ng m-3) and up to 22.49

437

ng m-3 (average 11.22 ng m-3) at the urban and landfill site, respectively. Its concentration was

438

higher than those of methyltetrols and C5 alkene triols suggesting probability of the vapour phase

439

reaction pathway to be dominant over the particulate phase reaction pathway of isoprene

440

degradation in atmosphere. Pinic, Pinonic and 3-Hydroxyglutaric acid are reported as the

441

oxidation products of monoterpenes (Fu et al., 2013) resulting from α/β-pinene oxidation. 3-

442

HGA was found to be the dominant species with an average concentration of 60.39 ng m-3 at

443

urban site and 75.45 ng m-3 at the landfill site. These are produced through the oxidation

444

reactions of pinene with ozone and OH radicals (Fu et al., 2010). Concentration of pinic acid was

445

found to be higher than the pinonic acid at urban site. However, pinic acid was not detected in

446

the landfill site samples.

447

3.2.8 Sterols

448

The presence of sterol compounds in the atmospheric aerosols has been related mainly to the

449

cooking activities and some have been reported to be source specific to biomass burning. The

450

total concentrations of sterols were 54945 ng m-3 at landfill site and 1756 ng m-3 at urban site.

451

Four sterol compounds, namely, cholesterol, ergosterol, stigmasterol and β-sitosterol were

452

detected in both sites’ aerosol samples. Of these four, β-sitosterol was found to be the dominant

453

species among others with an average of 5581 ng m-3 and 232 ng m-3 at landfill and urban site,

454

respectively (Figure 9). β-sitosterol and stigmasterol are found in leaves of terrestrial higher

455

plants and are emitted into atmosphere through their burning (Fu et al., 2010, Kawamura et al.,

456

2003). At landfill site β-sitosterol is present in much higher concentrations suggesting burning of

457

biomass to be the major cause. β-sitosterol is also produced during cooking activities as they are

458

present in plant oils (Fu et al., 2010). Cholesterol, reported to be a tracer for meat cooking and

459

marine organisms (Fu et al., 2010, Kawamura et al., 2003) was found to be the second most

460

abundant sterol compound at the landfill site. Ergosterol was found in higher concentrations at

461

landfill site (average 539 ng m-

16

462

3

) than urban site (average 47.4 ng m-3). It has been reported as a biomarker of fungal biomass in

463

atmospheric aerosols (Fu et al., 2010, Lau et al., 2006). The higher concentration of ergosterol

464

can be associated with the fungal decomposition of waste at the landfill site.

465

3.2.9 Sugars

466

Sugar compounds contribute to water-soluble organic carbon (WSOC) in aerosols and can be

467

used as tracers for primary biological aerosol particles (Aggarwal et al., 2013; Elbert et al., 2007;

468

Graham et al., 2003; Medeiros et al., 2006; Simoneit and Mazurek, 1982). Ten sugar compounds

469

(levoglucosan, arabitol, fructose, glucose, mannitol, inositol, sucrose, trehalose, glycerol and

470

erythritol) were detected in the aerosols at both the sites (Figure 10). The total concentration of

471

sugars was 16711 ng m-3 at urban site and 90141 ng m-3 at landfill site. Their concentrations are

472

several times higher than those reported in Chinese coastal urban aerosols (average 262 ng m-3 in

473

summer) (Wang et al., 2006). The higher concentrations at landfill site are consistent with those

474

of wax components such as n-alkanes and fatty acids.

475

In this study, levoglucosan was found to be one of the most abundant species among the

476

individually identified compounds with a concentration range of 1761- 4767 ng m−3 (average

477

2925 ng m−3) at urban and 103-22864 ng m−3 (average 11132 ng m−3) at landfill site, being much

478

higher than previous studies (Graham et al., 2002; Hoffer et al., 2006). These values are much

479

higher to those reported in Kolkata (75± 15 ng m-3) and Delhi aerosols (210 ±40 ng m-3)

480

(Chowdhury et al., 2007). Levoglucosan is formed during the pyrolysis of cellulose and has been

481

recognized as a tracer of biomass-burning (Simoneit et al., 1999). The higher concentration

482

reported at landfill site is due to the large amount of household and agricultural waste being

483

dumped and burnt in open. In present study, levoglucosan contribute up to 87% of total

484

identified sugars at urban site and 86% at landfill site which are comparable to the urban aerosols

485

collected from Chinese megacities (90%) (Wang et al., 2006). This suggests biomass burning to

486

be the major contributor of sugar compounds at both the sites.

487

Primary saccharides consist of glucose, fructose, inositol, sucrose, trehalose and reduced sugars

488

(sugar polyols) such as arabitol and mannitol. They are the tracers for resuspension of surface

489

soil and unpaved road dust, containing biological materials including pollen, fungi and bacteria

490

(Simoneit et al., 2004; Yttri et al., 2007). Their concentrations are higher in samples collected

491

from landfill site. Agricultural activities such as field burning of wheat straws contribute these 17

492

sugar compounds in the environment. The average concentration of primary saccharides

493

(fructose, glucose, inositol, sucrose, and trehalose) was 110.25 ± 65.41 ng m-3 at urban site,

494

being comparable to sugar polyols (arabitol and mannitol) (111.54 ± 55.98 ng m-3). In contrast,

495

the concentration of primary saccharides at landfill site was 221.13 ± 169.04 ng m-3, being lower

496

than sugar polyols (413.20 ± 49.53 ng m-3). These results suggest that sugar compounds mainly

497

originate from agricultural and household wastes being burnt in open.

498

4. Conclusion

499

Waste burning at dumping sites has grown to be one of the important sources of particulate

500

matter pollution in urban environments. Chemical composition of aerosols originating from

501

waste burning at a landfill site in Delhi were studied to outline the source specific species

502

qualitatively and quantitatively. In addition, chemical analysis was carried out on samples

503

collected from an urban area in Delhi to understand the extent and differences between the two

504

sites and the influence of open waste burning at landfill sites on the urban aerosols. The organic

505

compounds concentration detected at the landfill site (2456250 ng m-3) were several folds higher

506

in concentration than the urban site (50330 ng m-3). Also, the concentrations reported in this

507

study are significantly higher than that reported in previous studies from urban areas. The aerosol

508

chemical composition observed at the landfill site suggests a variety of waste being burned

509

leading to increased toxicity of the air for the persons working at these sites and in the nearby

510

regions. Fatty acids were found to be the most abundant class at both the sites. However, at urban

511

site fatty acids and sugars were found to be contributing equally to the total organic compounds.

512

Levoglucosan and C18:0 fatty acid was found to be most abundant compounds at urban and

513

landfill site, respectively. The WSOC/OC ratios observed suggested urban aerosols to be more

514

photochemically processed supporting the phenomenon of secondary pathways for formation of

515

phthalic acids. Lignin and resin products except 4-hydrobenzoic acid are first time reported to be

516

released from open waste burning activities in the present study.

517

The spontaneous fires occurring due to reasons such as high temperature resulting from

518

exothermic biological and chemical reactions and presence of combustible material are a

519

common sight at the landfill sites. The emissions originating from such fires are highly polluting

520

as the waste consists of a variety of materials which on burning at low temperatures emit toxic

521

species into the atmosphere. The present study is an attempt to report the chemical composition 18

522

of organic aerosols originating from open burning of landfill waste. The information presented

523

here may be important to estimate the role of waste burning aerosols in urban burden of

524

particulate matter.

525

Acknowledgement

526

RA thanks the University Grants Commission (UGC) for providing JRF fellowship (Ref No.

527

23196/(NET-DEC. 2015)). Director, CSIR-NPL is also acknowledged for providing necessary

528

facilities to carry out this work.

529

19

530

References

531 532 533 534 535

Agarwal, S., Aggarwal, S. G., Okuzawa, K., Kawamura, K., 2010. Size distributions of dicarboxylic acids, ketoacids, α-dicarbonyls, sugars, WSOC, OC, EC and inorganic ions in atmospheric particles over Northern Japan: implication for long-range transport of Siberian biomass burning and East Asian polluted aerosols. Atmospheric Chemistry and Physics. 10(13), 5839-5858.

536 537 538

Aggarwal, S. G., Kawamura, K., 2009. Carbonaceous and inorganic composition in longrange transported aerosols over northern Japan: Implication for aging of water-soluble organic fraction. Atmospheric Environment. 43(16), 2532-2540.

539 540 541 542

Aggarwal, S. G., Kawamura, K., Umarji, G. S., Tachibana, E., Patil, R. S., Gupta, P. K., 2013. Organic and inorganic markers and stable C-, N-isotopic compositions of tropical coastal aerosols from megacity Mumbai: sources of organic aerosols and atmospheric processing. Atmospheric Chemistry and Physics. 13(9), 4667-4680.

543 544 545 546

Bano, S., Pervez, S., Chow, J. C., Matawle, J. L., Watson, J. G., Sahu, R. K., Srivastava, A., Tiwari, S., Pervez Y. F., Deb, M. K. (2018). Coarse particle (PM10–2.5) source profiles for emissions from domestic cooking and industrial process in central India. Science of the Total Environment, 627, 1137-1145.

547 548 549

Bi, X., Sheng, G., Peng, P. A., Chen, Y., Zhang, Z., Fu, J., 2003. Distribution of particulateand vapor-phase n-alkanes and polycyclic aromatic hydrocarbons in urban atmosphere of Guangzhou, China. Atmospheric Environment. 37(2), 289-298.

550 551 552 553

Chowdhury, Z., Zheng, M., Schauer, J. J., Sheesley, R. J., Salmon, L. G., Cass, G. R., Russell, A. G., 2007. Speciation of ambient fine organic carbon particles and source apportionment of PM2.5 in Indian cities. Journal of Geophysical Research: Atmospheres. 112(D15).

554 555 556

Claeys, M., Graham, B., Vas, G., Wang, W., Vermeylen, R., Pashynska, V., Cafmeyer, J., Guyon, P., Maenhaut, W., 2004. Formation of secondary organic aerosols through photooxidation of isoprene. Science. 303(5661), 1173-1176.

557 558

Cogut, A., 2016. Open burning of waste: a global health disaster. R20 Regions of climate action.

559 560 561 562

Downard, J., Singh, A., Bullard, R., Jayarathne, T., Rathnayake, C. M., Simmons, D. L., Wels, B. R., Spak, S.N., Peters, T., Beardsley, D., Stanier, C. O., Stone, E. A., 2015. Uncontrolled combustion of shredded tires in a landfill–Part 1: Characterization of gaseous and particulate emissions. Atmospheric Environment. 104, 195-204.

563 564 565

Elbert, W., Taylor, P. E., Andreae, M. O., Pöschl, U., 2007. Contribution of fungi to primary biogenic aerosols in the atmosphere: wet and dry discharged spores, carbohydrates, and inorganic ions. Atmospheric Chemistry and Physics. 7(17), 4569-4588. 20

566 567 568

Fu, P. Q., Kawamura, K., Chen, J., Charriere, B., Sempere, R., 2013. Organic molecular composition of marine aerosols over the Arctic Ocean in summer: contributions of primary emission and secondary aerosol formation. Biogeosciences. 10(2), 653-667.

569 570 571 572

Fu, P. Q., Kawamura, K., Pavuluri, C. M., & Swaminathan, T., 2009. Molecular characterization of urban organic aerosol in tropical India: contributions of biomass/biofuel burning, plastic burning, and fossil fuel combustion. Atmospheric Chemistry & Physics Discussions, 9(5).

573 574 575 576

Fu, P. Q., Kawamura, K., Pavuluri, C. M., Swaminathan, T., Chen, J., 2010. Molecular characterization of urban organic aerosol in tropical India: contributions of primary emissions and secondary photooxidation. Atmospheric Chemistry and Physics. 10(6), 26632689.

577 578 579

Fu, P., Kawamura, K., Kanaya, Y., & Wang, Z., 2010. Contributions of biogenic volatile organic compounds to the formation of secondary organic aerosols over Mt. Tai, Central East China. Atmospheric Environment, 44(38), 4817-4826.

580 581 582 583

Fu, P., Kawamura, K., Okuzawa, K., Aggarwal, S. G., Wang, G., Kanaya, Y., Wang, Z., 2008. Organic molecular compositions and temporal variations of summertime mountain aerosols over Mt. Tai, North China Plain. Journal of Geophysical Research: Atmospheres. 113(D19).

584 585

Gargava, P., Chow, J. C., Watson, J. G., Lowenthal, D. H., 2014. Speciated PM 10 emission inventory for Delhi, India. Aerosol and Air Quality Research. 14(5), 1515-1526.

586 587 588 589

Graham, B., Guyon, P., Taylor, P. E., Artaxo, P., Maenhaut, W., Glovsky, M. M., ... Andreae, M. O., 2003. Organic compounds present in the natural Amazonian aerosol: Characterization by gas chromatography–mass spectrometry. Journal of Geophysical Research: Atmospheres. 108(D24).

590 591 592 593

Graham, B., Mayol‐Bracero, O. L., Guyon, P., Roberts, G. C., Decesari, S., Facchini, M. C., Artaxo, P., Maenhaut, W., Koll, P., Andreae, M. O., 2002. Water‐soluble organic compounds in biomass burning aerosols over Amazonia 1. Characterization by NMR and GC‐MS. Journal of Geophysical Research: Atmospheres. 107(D20), LBA-14.

594 595 596 597

Guenther, A., Hewitt, C. N., Erickson, D., Fall, R., Geron, C., Graedel, T., Harley, P., Klinger, L., Lerdau, M., McKay, W.A., Pierce, T., Sholes, B., Steinbrecher, R., Tallamraju, R., Taylor, J., Zimmerman, P., 1995. A global model of natural volatile organic compound emissions. Journal of Geophysical Research: Atmospheres. 100(D5), 8873-8892.

598 599 600

Guenther, A., Karl, T., Harley, P., Wiedinmyer, C., Palmer, P. I., Geron, C., 2006. Estimates of global terrestrial isoprene emissions using MEGAN (Model of Emissions of Gases and Aerosols from Nature. Atmospheric Chemistry and Physics. 6(11), 3181-3210.

21

601 602

Hodzic, A., Wiedinmyer, C., Salcedo, D., Jimenez, J. L., 2012. Impact of trash burning on air quality in Mexico City. Environmental science & technology. 46(9), 4950-4957.

603 604 605

Hoffer, A., Gelencsér, A., Blazso, M., Guyon, P., Artaxo, P., Andreae, M. O., 2006. Diel and seasonal variations in the chemical composition of biomass burning aerosol. Atmospheric Chemistry and Physics. 6(11), 3505-3515.

606 607 608

Hoornweg, D., Bhada-Tata, P., 2012. What a waste: A Global Review of Solid Waste Management, 15, 116 World Bank, Washington, DC. https://openknowledge.worldbank.org/handle/10986/17388 License: CC BY 3.0 IGO.

609 610 611

Jaffrezo, J. L., Aymoz, G., Delaval, C., Cozic, J., 2005. Seasonal variations of the watersoluble organic carbon mass fraction of aerosol in two valleys of the French Alps. Atmospheric Chemistry and Physics. 5(10), 2809-2821.

612 613 614 615

Jung, J., Tsatsral, B., Kim, Y. J., Kawamura, K., 2010. Organic and inorganic aerosol compositions in Ulaanbaatar, Mongolia, during the cold winter of 2007 to 2008: dicarboxylic acids, ketocarboxylic acids, and α‐dicarbonyls. Journal of Geophysical Research: Atmospheres. 115(D22).

616 617 618

Kalaitzoglou, M., Terzi, E., Samara, C., 2004. Patterns and sources of particle-phase aliphatic and polycyclic aromatic hydrocarbons in urban and rural sites of western Greece. Atmospheric Environment. 38(16), 2545-2560.

619 620 621

Kang, M., Fu, P., Aggarwal, S. G., Kumar, S., Zhao, Y., Sun, Y., Wang, Z., 2016. Size distributions of n-alkanes, fatty acids and fatty alcohols in springtime aerosols from New Delhi, India. Environmental pollution. 219, 957-966.

622 623 624

Kawamura, K., Kaplan, I. R., 1987. Motor exhaust emissions as a primary source for dicarboxylic acids in Los Angeles ambient air. Environmental Science & Technology. 21(1), 105-110.

625 626 627

Kawamura, K., & Pavuluri, C. M., 2010. New Directions: Need for better understanding of plastic waste burning as inferred from high abundance of terephthalic acid in South Asian aerosols. Atmospheric Environment. 44(39), 5320-5321.

628 629 630

Kawamura, K., Ishimura, Y., Yamazaki, K., 2003. Four years' observations of terrestrial lipid class compounds in marine aerosols from the western North Pacific. Global Biogeochemical Cycles. 17(1), 3-1.

631 632 633

Kawamura, K., Steinberg, S., Kaplan, I. R., 2000. Homologous series of C1–C10 monocarboxylic acids and C1–C6 carbonyls in Los Angeles air and motor vehicle exhausts. Atmospheric Environment. 34(24), 4175-4191.

22

634 635 636

Kaza, S., Yao, L., Bhada-Tata, P., Van Woerden, F., 2018. What a Waste 2.0: A Global Snapshot of Solid Waste Management to 2050. World Bank Publications. https://openknowledge.worldbank.org/handle/10986/30317 License: CC BY 3.0 IGO.

637 638

Kolattukudy, P. E., 1976. Chemistry and Biochemistry of Natural Waxes. Elsevier Scientific Pub. Co., Amsterdam.

639 640

Kumar, S., Aggarwal, S. G., Gupta, P. K., Kawamura, K., 2015. Investigation of the tracers for plastic-enriched waste burning aerosols. Atmospheric Environment. 108, 49-58.

641 642 643 644

Kumar, S., Aggarwal, S. G., Sarangi, B., Malherbe, J., Barre, J. P., Berail, S., Seby, F., Donard, O. F., 2018. Understanding the Influence of Open-waste Burning on Urban Aerosols using Metal Tracers and Lead Isotopic Composition. Aerosol and Air Quality Research. 18(9), 2433-2446.

645 646 647

Lau, A. P., Lee, A. K., Chan, C. K., Fang, M., 2006. Ergosterol as a biomarker for the quantification of the fungal biomass in atmospheric aerosols. Atmospheric Environment. 40(2), 249-259.

648 649 650

Lechevalier, M. P., De Bievre, C., Lechevalier, H., 1977. Chemotaxonomy of aerobic actinomycetes: phospholipid composition. Biochemical Systematics and Ecology. 5(4), 249260.

651 652

Li, G., Lei, W., Bei, N., Molina, L. T., 2012. Contribution of garbage burning to chloride and PM2.5 in Mexico City. Atmospheric Chemistry and Physics. 12(18), 8751-8761.

653 654 655

Li, W., Peng, Y., Bai, Z., 2010. Distributions and sources of n-alkanes in PM2.5 at urban, industrial and coastal sites in Tianjin, China. Journal of Environmental Sciences. 22(10), 1551-1557.

656 657 658 659

Li, X., Pavuluri, C. M., Yang, Z., He, N., Tachibana, E., Kawamura, K., & Fu, P. Q., 2019. Large contribution of fine carbonaceous aerosols from municipal waste burning inferred from distributions of diacids and fatty acids. Environmental Research Communications, 1(7), 071005.

660 661 662

Matawle, J., Pervez, S., Dewangan, S., Tiwari, S., Bisht, D. S., Pervez, Y. F., 2014. PM2.5 chemical source profiles of emissions resulting from industrial and domestic burning activities in India. Aerosol and Air Quality Research, 14, 2051-2066.

663 664 665

Medeiros, P. M., Conte, M. H., Weber, J. C., Simoneit, B. R., 2006. Sugars as source indicators of biogenic organic carbon in aerosols collected above the Howland Experimental Forest, Maine. Atmospheric Environment. 40(9), 1694-1705.

666 667

Mkoma, S. L., Kawamura, K., 2013. Molecular composition of dicarboxylic acids, ketocarboxylic acids, α-dicarbonyls and fatty acids in atmospheric aerosols from Tanzania,

23

668 669

East Africa during wet and dry seasons. Atmospheric Chemistry and Physics. 13(4), 22352251.

670 671 672

Mochida, M., Kitamori, Y., Kawamura, K., Nojiri, Y., Suzuki, K., 2002. Fatty acids in the marine atmosphere: Factors governing their concentrations and evaluation of organic films on sea‐salt particles. Journal of Geophysical Research: Atmospheres. 107(D17), AAC-1.

673 674 675

Oliveira, C., Pio, C., Alves, C., Evtyugina, M., Santos, P., Gonçalves, V., Harrad, S., 2007. Seasonal distribution of polar organic compounds in the urban atmosphere of two large cities from the North and South of Europe. Atmospheric Environment. 41(27), 5555-5570.

676 677 678 679

Pervez, S., Verma, M., Tiwari, S., Chakrabarty, R. K., Watson, J. G., Chow, J. C., Abhilash Panicker, S., Deb, M. K., Siddiqui, M. N., Pervez, Y. F., 2019. Household solid fuel burning emission characterization and activity levels in India. Science of The Total Environment, 654, 493-504.

680 681 682

Rajput, P., Sarin, M., Sharma, D., Singh, D., 2014. Characteristics and emission budget of carbonaceous species from post-harvest agricultural-waste burning in source region of the Indo-Gangetic Plain. Tellus B: Chemical and Physical Meteorology. 66(1).

683 684 685 686

Ram, K., Sarin, M. M., Tripathi, S. N., 2012. Temporal trends in atmospheric PM2.5, PM10, elemental carbon, organic carbon, water-soluble organic carbon, and optical properties: impact of biomass burning emissions in the Indo-Gangetic Plain. Environmental science & technology. 46(2), 686-695.

687 688 689

Rogge, W. F., Hildemann, L. M., Mazurek, M. A., Cass, G. R., Simoneit, B. R., 1993. Sources of fine organic aerosol. 2. Noncatalyst and catalyst-equipped automobiles and heavy-duty diesel trucks. Environmental science & technology. 27(4), 636-651.

690 691 692

Rogge, W. F., Hildemann, L. M., Mazurek, M. A., Cass, G. R., Simoneit, B. R., 1991. Sources of fine organic aerosol. 1. Charbroilers and meat cooking operations. Environmental Science & Technology. 25(6), 1112-1125.

693 694 695

Schauer, J. J., Kleeman, M. J., Cass, G. R., Simoneit, B. R., 2001. Measurement of emissions from air pollution sources. 3. C1− C29 organic compounds from fireplace combustion of wood. Environmental Science & Technology. 35(9), 1716-1728.

696 697 698

Schefuß, E., Ratmeyer, V., Stuut, J. B. W., Jansen, J. F., Damsté, J. S. S., 2003. Carbon isotope analyses of n-alkanes in dust from the lower atmosphere over the central eastern Atlantic. Geochimica et Cosmochimica Acta. 67(10), 1757-1767.

699 700 701

Shakya, K. M., Ziemba, L. D., Griffin, R. J., 2010. Characteristics and sources of carbonaceous, ionic, and isotopic species of wintertime atmospheric aerosols in Kathmandu Valley, Nepal. Aerosol Air Qual. Res. 10, 219-230.

24

702 703

Simoneit, B. R., 2002. Biomass burning—a review of organic tracers for smoke from incomplete combustion. Applied Geochemistry. 17(3), 129-162.

704 705 706

Simoneit, B. R., Mazurek, M. A., 1982. Organic matter of the troposphere—II. Natural background of biogenic lipid matter in aerosols over the rural western United States. Atmospheric Environment. 16(9), 2139-2159.

707 708

Simoneit, B. R., Cox, R. E., Standley, L. J., 1988. Organic matter of the troposphere—IV. Lipids in Harmattan aerosols of Nigeria. Atmospheric Environment. 22(5), 983-1004.

709 710 711 712

Simoneit, B. R., Elias, V. O., Kobayashi, M., Kawamura, K., Rushdi, A. I., Medeiros, P. M., Rogge, W. F., Didyk, B. M., 2004. Sugars dominant water-soluble organic compounds in soils and characterization as tracers in atmospheric particulate matter. Environmental Science & Technology. 38(22), 5939-5949.

713 714 715 716

Simoneit, B. R., Kobayashi, M., Mochida, M., Kawamura, K., Huebert, B. J., 2004b. Aerosol particles collected on aircraft flights over the northwestern Pacific region during the ACE‐ Asia campaign: Composition and major sources of the organic compounds. Journal of Geophysical Research: Atmospheres. 109(D19).

717 718 719

Simoneit, B. R., Medeiros, P. M., Didyk, B. M., 2005. Combustion products of plastics as indicators for refuse burning in the atmosphere. Environmental science & technology. 39(18), 6961-6970.

720 721 722 723

Simoneit, B. R., Rogge, W. F., Mazurek, M. A., Standley, L. J., Hildemann, L. M., Cass, G. R., 1993. Lignin pyrolysis products, lignans, and resin acids as specific tracers of plant classes in emissions from biomass combustion. Environmental science & technology. 27(12), 2533-2541.

724 725 726

Simoneit, B. R., Schauer, J. J., Nolte, C. G., Oros, D. R., Elias, V. O., Fraser, M. P., Rogge, W. F., Cass, G. R., 1999. Levoglucosan, a tracer for cellulose in biomass burning and atmospheric particles. Atmospheric Environment. 33(2), 173-182.

727 728 729 730

Surratt, J. D., Murphy, S. M., Kroll, J. H., Ng, N. L., Hildebrandt, L., Sorooshian, A., Szmigielski, R., Vermeylen, R., Maenhaut, W., Claeys, M., Flagan, R. C., Seinfeld, J. H., 2006. Chemical composition of secondary organic aerosol formed from the photooxidation of isoprene. The Journal of Physical Chemistry. 110(31), 9665-9690.

731 732 733

Timonen, H. J., Saarikoski, S. K., Aurela, M. A., Saarnio, K. M., Hillamo, R. E., 2008. Water-soluble organic carbon in urban aerosol: concentrations, size distributions and contribution to particulate matter. Boreal Environment Research. 13, 335-346.

734 735 736

Wang, G., Kawamura, K., 2005. Molecular characteristics of urban organic aerosols from Nanjing: A case study of a mega-city in China. Environmental Science & Technology. 39(19), 7430-7438.

25

737 738 739

Wang, G., Kawamura, K., Hatakeyama, S., Takami, A., Li, H., Wang, W., 2007. Aircraft measurement of organic aerosols over China. Environmental Science & Technology. 41(9), 3115-3120.

740 741 742

Wang, G., Kawamura, K., Lee, S., Ho, K., Cao, J., 2006. Molecular, seasonal, and spatial distributions of organic aerosols from fourteen Chinese cities. Environmental Science & Technology. 40(15), 4619-4625.

743 744 745 746 747 748

Wang, W., Kourtchev, I., Graham, B., Cafmeyer, J., Maenhaut, W., Claeys, M., 2005. Characterization of oxygenated derivatives of isoprene related to 2‐methyltetrols in Amazonian aerosols using trimethylsilylation and gas chromatography/ion trap mass spectrometry. Rapid Communications in Mass Spectrometry: An International Journal Devoted to the Rapid Dissemination of Up‐to‐the‐Minute Research in Mass Spectrometry. 19(10), 1343-1351.

749 750 751

Wiedinmyer, C., Yokelson, R. J., Gullett, B. K., 2014. Global emissions of trace gases, particulate matter, and hazardous air pollutants from open burning of domestic waste. Environmental Science & Technology. 48(16), 9523-9530.

752 753 754

Yassaa, N., Meklati, B. Y., Cecinato, A., Marino, F., 2001. Particulate n-alkanes, n-alkanoic acids and polycyclic aromatic hydrocarbons in the atmosphere of Algiers City Area. Atmospheric Environment. 35(10), 1843-1851.

755 756 757

Yttri, K. E., Dye, C., Kiss, G., 2007. Ambient aerosol concentrations of sugars and sugaralcohols at four different sites in Norway. Atmospheric Chemistry and Physics. 7(16), 42674279.

758

26

Table 1: Mass, OC and WSOC concentrations at the two sampling sites

759

Site

TSP (µg m-3)

WSOC (µgC m-3)

OC (µgC m-3)

WSOC/OC

OC/TSP

Urban (n=5)

724

35.36

141

0.26

0.19

Landfill

3780

229

2538

0.09

0.62

(n=7)

27

760 761

Table 2: Concentrations of organic compounds detected in aerosols over an urban and landfill site in Delhi, India (ng m-3). Compound I. Alkanes C16 C18 C20 C22 C24 C25 C26 C27 C28 C29 C30 C31 C32 C33 C34 C35 C36 Subtotal II. Aromatic Acids Benzoic Acid O-Phthalic Acid M-Phthalic Acid P-Phthalic Acid Subtotal III. Fatty Acids FA C 12:0 FA C 14:0 FA C 16:0 FA C 16:1 FA C 17:0 FA C 18:0 FA C 18:1 FA C 19:0 FA C 20:0

Urban site (n=5) Min Max

Average

Landfill site (n=7) Min Max

Average

n.d.* n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. 4283

n.d. n.d. 13.56 63.13 100.13 98.72 100.68 126.00 108.76 187.77 114.85 241.70 160.04 201.44 75.26 67.55 46.26

n.d. n.d. 5.18 22.60 51.24 52.98 56.09 70.59 60.83 106.88 54.19 126.77 66.48 93.18 41.34 28.52 19.74

n.d. n.d. n.d. 351.24 467.54 497.76 779.95 701.19 811.47 n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. 637042

1375 5980 7391 7639 8860 9895 13373 15303 16498 21446 20134 28831 17085 24925 20378 18023 19081

334.51 1642 2379 3125 3706 4074 5020 5694 6147 6605 6052 8941 6991 8514 7335 6885 7559

9.71 68.62 3.84 240.88 3934

25.86 239.66 15.51 1165.79

19.10 123.95 8.81 634.91

71.28 n.d. n.d. n.d. 308909

5726 374.83 208.38 67856

1259 186.04 129.84 42555

43.40 18.04 365.15 8.60 21.27 131.92 27.58 11.57 44.20

63.34 114.41 964.42 23.01 29.21 419.28 430.46 15.95 493.11

33.43 35.37 634.25 6.32 14.61 271.76 116.59 5.50 172.94

1420 n.d. 12726.36 n.d. n.d. 5481 n.d. n.d. 307.36

13704 15596 89622 4551 n.d. 368992 62058 n.d. 3874

6738 3564 52774 2153 n.d. 76090 19624 n.d. 1416

28

FA C 21:0 FA C 22:0 FA C 22:1 FA C 23:0 FA C 24:0 FA C 25:0 FA C 26:0 FA C 27:0 FA C 28:0 FA C 29:0 FA C 30:0 FA C 31:0 FA C 32:0 Subtotal IV. Lignin products Dehydroabietic acid Syringic acid Vanillic acid 4-hydroxybenzoic acid Total V. Phthalates Dimethyl Diethyl Di-Iso-Butyl Di-N-Butyl Di-(2-Ethylhexyl) Total VI. Polyacids Glyceric Acid DL-Malic Acid DL-Tartalic Acid Total VII. SOA Tracers Pinonic Acid Pinic Acid 3-HGA 2−Methylglycericacid 2-Methylthreitol

10.20 61.90 19.17 68.87 93.39 83.48 190.63 49.04 296.57 61.97 284.72 49.16 118.09 16823

20.27 145.61 308.99 91.15 214.53 136.30 484.94 676.08 527.96 79.89 443.20 78.82 266.95

11.53 90.90 119.68 49.65 142.19 85.58 316.93 193.27 409.84 71.14 351.92 47.95 183.30

n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. 1218120

n.d. 4329 14511 n.d. 3457 567.35 1780 379.77 1021 n.d. 880.32 n.d. n.d.

n.d. 1687 8119 n.d. 1057 81.05 389.82 54.25 145.83 n.d. 125.76 n.d. n.d.

21.23 21.24 24.74 n.d.

130.70 195.95 112.05 196.94

57.06 77.12 57.26 100.10

n.d. n.d. n.d. n.d.

812.38 331.84 267.92 1515

353.46 127.39 108.58 811.21

1458

9805

n.d. n.d. 128.12 15.25 105.73 3596

n.d. n.d. 994.81 58.45 509.29

n.d. n.d. 387.22 29.18 302.71

n.d. n.d. 2650 200 1727.13 135365

n.d. n.d. 11136 768.57 42671

n.d. n.d. 4763 379.23 14195

114.76 30.63 n.d. 1279

284.50 82.71 n.d.

199.56 56.16 n.d.

41.08 30.95 n.d. 881

130.07 98.6 n.d.

74.76 51.14 n.d.

3.44 8.14 22.68 6.92 1.93

7.05 14.72 102.81 84.11 3.04

3.26 4.57 60.39 21.92 1.88

n.d. n.d. n.d. n.d. n.d.

194.39 n.d. 149.62 22.49 1.71

53.65 n.d. 75.45 11.22 0.24

29

2-Methylerythritol cis-2-Methyl-1,3,4Trihydroxy-1-Butene 3-Methyl-2,3,4Trihydroxy-1-Butene Trans-2-Methyl1,3,4-Trihydroxy-1Butene Total VIII. Sterols Cholesterol Ergosterol Stigmasterol B-Sitosterol Total IX. Sugars Levoglucosan Arabitol Mannitol Α-Fructose Β-Fructose Α-Glucose Β-Glucose Inositol Sucrose Trehalose Erythritol Glycerol Total 762

*

5.12 0.24

6.87 0.94

4.71 0.24

n.d. n.d.

23.19 n.d.

8.29 n.d.

0.30

0.82

0.22

n.d.

n.d.

n.d.

0.97

2.90

0.77

n.d.

n.d.

n.d.

490

1042

10.30 n.d. 18.19 82.63 1757

59.43 237.15 75.30 578.29

31.68 47.43 39.71 232.47

n.d. n.d. n.d. n.d. 54945

2747 3775 1209 12863

1328 539.33 400.67 5581

1762 23.55 13.55 6.14 3.55 7.70 14.34 10.94 7.50 9.50 28.70 61.39 16711

4767 40.49 25.12 19.73 12.90 36.96 48.32 22.88 128.69 34.48 84.59 246.74

2925 30.23 14.39 11.28 7.01 20.78 29.52 15.24 46.03 24.49 51.21 166.74

102.64 n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. 21.49 63.39 90142

22864 147.90 171.94 42.79 50.89 55.46 104.27 45.77 146.61 90.81 839.71 4964.53

11132 54.02 64.03 19.61 16.89 14.93 23.20 23.28 83.06 40.16 269.85 1136.46

n.d.: not detected

30

763 764

Table 3: Percentage contribution of individual class of compounds to OC and WSOC at the two sampling sites Compound Class

765 766

Min

Urban Max

Alkanes Aromatic Acids Fatty Acids Lignin Products Phthalates Polyacids SOA Tracers Sterols Sugars

n.d.# 0.19 1.04 0.07 0.28 0.04 0.02 0.09 0.71

0.75 0.47 2.66 0.22 0.47 0.06 0.04 0.44 1.49

Alkanes Aromatic Acids Lignin Products Phthalates Polyacids SOA Tracers Sterols Sugars

n.d. 0.81 0.21 0.88 0.16 0.08 0.27 3.19

3.70 2.09 1.07 2.43 0.28 0.15 2.19 6.33

Average Min To OC 0.51 0.95 0.32 0.01 1.87 0.48 0.12 n.d. 0.35 0.15 0.05 n.d. 0.03 0.000 0.19 n.d. 1.08 n.d. To WSOC 2.04 8.56 1.22 0.08 0.50 0.00 1.42 1.69 0.20 0.00 0.11 0.00 0.84 0.00 4.21 0.01

Landfill Max Average 3.80 2.26 6.67 0.06 2.83 0.006 0.006 0.46 0.40

2.63 1.41 3.96 0.05 0.84 0.002 0.004 0.26 0.28

45.22 25.17 0.91 25.48 0.06 0.07 5.00 5.57

29.81 15.52 0.52 8.61 0.03 0.04 2.98 3.15

*All the quantified organic compounds were converted to carbon contents to calculate the OC and WSOC ratios. # n.d.: not detected

31

767

(a)

(b)

n-alkanes, 8.51 Aromatic acids, 7.82

Aromatic acids, 12.58

Sugars, 33.20 n-alkanes, 25.94 Fatty Acid, 49.59

Fatty Acid, 33.43

Sterols, 3.49 [CATEGORY NAME]*, [VALUE] Polyacids, 2.54

Sugars, 3.67 Sterols, 2.24 [CATEGORY Phthalates, Lignin NAME]*, [VALUE] products, [VALUE] Polyacids, 0.04 0.40

[CATEGORY Lignin NAME], products, 2.90 [VALUE]

*SOA tracers: Secondary Organic Aerosol tracers. Refer Table 2.

Figure 1: Percentage contribution of compound classes to total organic compounds at (a) urban site and (b) landfill site

32

768

Figure 2: Mass concentrations (ng m-3) of detected n-alkanes at landfill and urban site

33

769

Figure 3: Mass Concentrations (ng m-3) of aromatic acids detected in aerosols at landfill and urban sites.

34

770

Figure 4: Mass concentrations (ng m-3) of C12:0-C32:0 fatty acids reported in landfill and urban site aerosols

35

771

Figure 5: Mass concentrations (ng m-3) of lignin and resin products reported in landfill and urban site aerosols

36

772

Figure 6: Mass concentrations (ng m-3) of phthalate ester compounds detected in landfill and urban site aerosols

37

773

Figure 7: Mass concentrations (ng m-3) of polyacids detected in landfill and urban site aerosols

38

774

Figure 8: Mass concentrations (ng m-3) of biogenic SOA tracers detected in landfill and urban site aerosols

39

775

Figure 9: Mass concentrations (ng m-3) of sterol compounds detected in landfill and urban site aerosols

40

776

Figure 10: Mass concentrations (ng m-3) of sugar compounds detected in landfill and urban site aerosols

41

Highlights: •

The organic chemical characteristics of waste burning aerosols from a landfill and an urban site of Delhi are studied

•

Fatty acids were found to be the most abundant class at both the sites

•

However, at urban site fatty acids and sugars were found to be contributing equally to the total organic compounds

•

Levoglucosan and C18:0 fatty acid was found to be most abundant compounds at urban and landfill site, respectively.

•

Lignin and resin products, except 4-hydrobenzoic acid are first time reported to be released from open waste burning activities in the present study.

Declaration of interest statement

All authors have only academic purpose and interest to publish this work. All are involved equally in all the work from sampling, analysis and writing the work.