Seasonal and diurnal characteristics of carbonyls in the urban atmosphere of Changsha, a mountainous city in south-central China

Environmental Pollution 253 (2019) 259e267

Contents lists available at ScienceDirect

Environmental Pollution journal homepage: www.elsevier.com/locate/envpol

Seasonal and diurnal characteristics of carbonyls in the urban atmosphere of Changsha, a mountainous city in south-central China* Zhaohui Jiang*, Xuan Zheng, Haiqing Zhai, Yujiao Wang, Qiong Wang, Zhishu Yang School of Chemistry and Food Engineering, Changsha University of Science and Technology, Changsha, 410114, PR China

a r t i c l e i n f o

a b s t r a c t

Article history: Received 3 November 2018 Received in revised form 29 June 2019 Accepted 30 June 2019 Available online 3 July 2019

Seasonal and diurnal variations of carbonyl compounds were investigated in the ambient air of a mountainous city in China, from September 2014 to July 2015. The most abundant carbonyl compounds are formaldehyde, acetaldehyde and acetone, propionaldehyde and methacryladehyde (MACR), which were all measured in most samples. The average concentrations of formaldehyde, acetaldehyde, acetone, propionaldehyde and MACR in the atmosphere in Changsha were broken down into each season: 6.57, 3.29, 3.66, 0.67 and 0.54 mg/m3 respectively during Spring, 14.09, 8.28, 9.02, 1.28 and 0.6 mg/m3, respectively during Summer, 9.24, 5.48, 8.62, 0.73 and 0.62 mg/m3, respectively during Autumn, and 5.88, 4.84, 7.84, 0.87 and 0.26 mg/m3 respectively during Winter. And majority of the species had higher concentration during noon, showing photochemical oxidation and human activities played an important role in diurnal variation. The highest average C1/C2 (formaldehyde/acetaldehyde) ratio was observed in summer (2.10) compared to those (1.33e2.03) in other seasons, implying the photochemical activities had a positive effect on increasing the ratio of C1/C2. In this study, the monthly concentration of formaldehyde produced from isoprene accounts for 4.8%e39.1% of formaldehyde in ambient air. Strong correlation among some carbonyl compounds means that they came from the same sources. Photochemical reaction was the main source of carbonyl compounds in summer and vehicular exhaust (gasoline and diesel engines) in winter. Changsha is not a completely urbanized city and it is rich in vegetation of broadleaf evergreen shrubs. Both atmospheric photochemical reactions and anthropogenic sources, including vehicular exhaust and industrial processes, dominate the levels of carbonyls. The ILTCR and HQ values of formaldehyde and acetaldehyde are 1.23E-04 and 1.34E-05, 2.80E-01 and 1.86E-01, respectively. © 2019 Elsevier Ltd. All rights reserved.

Keywords: Carbonyls Urban atmosphere Photochemical activities Seasonal variation Changsha

1. Introduction Carbonyl compounds play an important role in chemical reactions occurring in the troposphere because they are usually the first stable intermediate in the photo-oxidation mechanism of organic compounds (Carlier P et al., 1986). At the same time, it is also an important environmental pollutant and the main component of photochemical smog (Possanzini M et al., 1996). Carbonyls are emitted from biogenic sources, atmospheric photochemical reactions and primary anthropogenic sources (Kean et al., 2001; Kim et al., 2008; Seco et al., 2007; Guo et al., 2009). Among them, biogenic sources include incomplete combustion architectural

* This paper has been recommended for acceptance by David Carpenter. * Corresponding author. E-mail addresses: [email protected], [email protected] (Z. Jiang).

https://doi.org/10.1016/j.envpol.2019.06.127 0269-7491/© 2019 Elsevier Ltd. All rights reserved.

decoration. Anthropogenic sources include human activities such as smoking, cooking and heating. Some carbonyl compounds are harmful to human health and cause irritation to the skin, eyes and respiratory system (Chen et al., 2016). A large number of published studies have examined formaldehyde and acetaldehyde. Risk assessment of these studies focus on indoor dwellings within European Union countries, indicating that carcinogenic risks are always higher than the acceptable risk (Karakitsios, S et al., 2014; Sarigiannis D.A et al., 2011). The concentration of carbonyl compounds in outdoor atmosphere is also inseparable from human health. In recent years, ambient levels and sources of carbonyl compounds have been receiving much attention. Some researchers have reported the seasonal and diurnal changes of carbonyls (Cheng et al., 2014; Guo et al., 2016; Jiang et al., 2016; Lü et al., 2010). At present, the investigation of atmospheric carbonyl compounds in urban areas of China mainly focuses on Guangzhou, Shanghai, Beijing, Xi'an (Lü et al., 2010; Feng et al., 2005; Pang and

260

Z. Jiang et al. / Environmental Pollution 253 (2019) 259e267

Mu., 2006; Xu et al., 2010; Dai et al., 2012). In recent years, with the rapid development of industrialization and urbanization, the air quality pollution has become a major concern in Changsha. The number of motor vehicles in Changsha has reached 2 million in 2015, and it has grown rapidly at a rate of more than 200,000 vehicles per year, according to Hunan Provincial Government Website. The main goals are to provide an important scientific basis for rational assessment of environmental and health effects of carbonyls and explore the main control strategies of carbonyls. 2. Material and methods 2.1. Study area Changsha is the capital city of Hunan province and the most important city in south-central China. The famous Yuelu Mountain is located in Changsha city. It is an important central city (11,819 square kilometers) and reaches of the Yangtze River with a population of 7.65 million people. The position of two sampling sites in Changsha was shown in Fig.1. The sampling performed was based on the method of US EPATO11, and the sampling Site 1 is in the 9th school building of Changsha University of Science and Technology, located at No.45, Chiling Road, Tianxin District, Changsha city, Hunan province, China. It is close to the main road of Furong South Road and Shuyuan South Road in Changsha. The No. 9 teaching building is located near the gate of the university and is about 100 m away from the road. There are a large number of residential buildings nearby. It is located in the downtown area of Changsha, so the sampling site is very representative. The sampling time is from 7:00 to 19:00 h (Beijing Time, BT) from September 2014 to July 2015 with 2 h for each sample and a total of 6 samples are collected every day. The semi-urban site (Site 2) is located at No.960, Wanjiali Nan Road, Yuhua District, Changsha City, Hunan Province, China. The sampling time is from 7:00 to 19:00 h (BT) from December 2014 to January 2015. 2.2. Carbonyl sampling and analysis This method had been used in my previous research (Jiang et al.,

2016). The sampling and analysis methods for carbonyls in the atmosphere mainly refer to the US EPA-TO11. The method is to use chromatographic pure acetonitrile (ACN) to recrystallize 2,4dinitrophenylhydrazine (DNPH) three times. Each sample cartridge was rinsed with 10 mL acetonitrile. Meanwhile, 300 mg of dried DNPH crystals and 3 drops of phosphoric acid are coated slowly in the sample cartridges. Before using the sample cartridges, we connected them in series, dried them in pure nitrogen (99.9999%), sealed them in aluminum foil bags and stored them in a refrigerator at 4
C. In our research, detection took place within 30 days after sampling. Sampling devices include flow meters, sampling pumps and ozone removal devices. The power source of sampling devices is the sampling pump (NMP830KNDC, KNF, Germany). We first checked the sampling system air tightness before sampling. Sampling flow range controlled at 0.9e1.1 L/min. The flow rate was measured at the beginning and the end of the sampling to calculate the sampling volume. After sampling, the silicone column was immediately covered with the lid in a foil bag and then returned to the lab for storage in the refrigerator. In addition, no air enters into the postprocessing of the blank samples and field blank samples. The field blank was treated identically to the samples except that no air was drawn through the cartridge. At each sample site, we collect two field samples with the spare column to evaluate the breakthrough. The derivative of carbonyls on the cartridges was slowly eluted by 5.0 mL acetonitrile and then detected by HPLC. The high performance liquid chromatograph (HPLC) analysis system consisting of a pump and an injection needle was connected to a diode array detector with a wavelength of 360 nm and was separated on a Unisol C18 column (5 mm, 4.6 mm  250 mm, Agela, China). The mobile phase was acetonitrile/water (77/23, V/V), the flow rate was 1 mL/min, and the injection volume was 20 mL every time. 2.3. Quality assurance and quality control This is based on the retention time and the peak area of the carbonyl compound qualitative and quantitative analysis. Excellent linearity (R2 > 0.999) was observed for the HPLC calibration of derivatives. Using two series of silica gel column to determine the adsorption efficiency, in the first Silica gel column we found more

Fig. 1. The position of two sampling sites in Changsha. (S1): Urban ambient site; (S2): Semi-urban ambient site.

Z. Jiang et al. / Environmental Pollution 253 (2019) 259e267

261

where, SF (mg/(kg$day)) is the cancer slope factor, taking from EPA (http://www.epa.gov/iris). Non-cancer risk was expressed as hazard quotient (HQ). The hazard quotient was calculated according to Eq. (3) (Zhang et al., 2012):

average concentration of 6.57, 3.66, 3.29 mg/m3, respectively in spring, 14.09, 9.02, 8.28 mg/m3, respectively in summer, 9.24, 8.62, 5.48 mg/m3, respectively in autumn, and 5.88, 7.84, 4.84 mg/m3 respectively in winter, which is in line with some research trends (Huang et al., 2009; Jiang et al., 2016). The concentration of carbonyl compounds is often affected by a number of factors, such as vehicular exhaust, combustion, metrological conditions, photochemical oxidation and photo degradation
n et al., 2007; Pang et al., 2009; removal (Moussa et al., 2006; Cero Pang and Lee., 2010; Guo et al., 2016). The order of the average total concentration of carbonyl groups from high to low is summer > spring > autumn > winter, and the trend of the same season
n et al., is similar to that of some studies (Pang and Mu., 2006; Cero 2007; Lü et al., 2010). It was noticed that concentration of formaldehyde was extremely high in summer. The total concentrations of carbonyls were 33.27 mg/m3 in summer and 19.69 mg/m3 in winter. It suggests that photochemical activity and temperature played an important role in the formation of carbonyls during the summer
n et al., 2007; Wang et al., 2010). However, the campaign (Cero highest concentration of MACR was in autumn. Some studies (Borbon et al., 2002; Cheng et al., 2014) claimed that local characteristics including field types and meteorological conditions have similar effects on the removal or emission of carbonyl compounds. The difference in research results in some regions potentially due to different meteorological factors. Wet sedimentation as one of the main ways to remove pollutants in the atmosphere. Strong light and hot weather in summer may be the causes of high concentration of carbonyls. The average diurnal variations of the formaldehyde, acetaldehyde and acetone in each season are shown in Fig. 2. The average concentration of formaldehyde was higher between 13:00 and 15:00 h (BT). In Nanning, the ambient acetaldehyde concentration is lower at noon and evening in spring, summer and autumn. (Guo et al., 2016). But in this study, concentration levels of acetaldehyde were higher between 13:00 and 15:00 h (BT) in spring and summer. This suggests automobile exhaust is also an important source of these carbonyls. Acetone concentration levels were higher between 11:00 and 15:00 h (BT) except in winter, which may be due to the presence of acetone in the atmosphere for a long time (Atkinson, 2000; Pang and Lee, 2010). Therefore, the source and sinks of different carbonyls were not seem to be identical (Lü et al., 2010).

HQ ¼ LEC=RfC

3.2. Source interpretation through correlations

than 98% carbonyl compounds. The content of carbonyl compounds in the field blank samples and experimental blank samples was in the same order of magnitude, indicating that they were not contaminated. The relative standard deviation (RSD) of all carbonyl compounds measured is not more than 5%. The limits of detection (LOD) were determined by 10 analyses at the minimum concentration working standard. For 120L sample volume and for various carbonyls, the LOD in this study was estimated to be within the range of 0.208e0.416 mg/m3. 2.4. Exposure and risk assessment In our study, the non-cancer hazard and integrated lifetime cancer risk (ILTCR) were estimated. The daily exposure (E) of an individual by intake process was calculated from Eq. (1) (Zhang et al., 2012):

E ¼ C  Ira  Eda =Bwa

Variable

description

E(mg/(kg$day))

Daily exposure

C (mg/m3)

Concentration of the pollutant

3

Value

Ira (m /hr)

Inhalation rate*, adult

0.83*

Eda (hr/day) Bwa (kg)

Exposure duration, adult Body weight, adult

24 65

* The value of inhalation rate (adult) is taken from US EPA (1997).

The ILTCR was calculated from Eq. (2) (Zhang et al., 2012):

ILTCR ¼ E  SF

(2)

(3)

where LEC and RfC are yearly average daily received concentration (mg/(kg$day)) and the reference concentration the (mg/(kg$day)), respectively. The RfC was taken from EPA (https://www.epa.gov/ iris) and OEHHA (http://www.arb.ca.gov/toxics/healthval/acute. pdf) (Zhang et al., 2012). 3. Results and discussion 3.1. Seasonal and diurnal variations Levels of formaldehyde, acetaldehyde, acetone, propionaldehyde and MACR, which were detected in most samples, collected at the urban site (S1) in Changsha from September 2014 to July 2015 are shown in Table 1. The meteorological parameters are necessary which were recorded as shown in Table 2. The temperature here varies greatly between summer and winter, more than 20
C. The summer relative humidity (74.8%) is higher than that in winter (53.4%) and the sunshine hours in summer were more than that of winter as well. The total concentration of five carbonyls ranged from 14.73 to 33.27 mg/m3. Formaldehyde, acetone and acetaldehyde were to be the most abundant carbonyl compounds, with the

The coefficient of determination of the concentration of carbonyls in the atmosphere can determine whether they are the same sources and sinks (Louis and Hanwant., 1986). The correlations of 5 carbonyl compounds in the four seasons were evaluated by linear regression analysis and the correlation coefficients are shown in Table 3. Overall analysis shows strong correlation between formaldehyde and acetaldehyde all year long, which implies that there are common sources and sinks. Formaldehyde and acetaldehyde may come from both automobile exhaust (gasoline and diesel engines) and the secondary production of photochemical reaction (Lü et al., 2010). The high concentration of acetone is attributed to the slow rate of photolysis in the atmosphere. As shown in Table 3, the total carbonyl compounds have good correlation in autumn and winter, except for acetaldehyde with MACR which suggest that vehicular exhaust was the main source in autumn and winter. This evidence is consistent with some previous studies (Ho et al., 2002; Dai et al., 2012). A study reported that the global mixture ratio of acetone is largely biogenic (Singh et al., 2000; Dai et al., 2012). In this study, acetone was strongly associated with formaldehyde, except in summer, indicating that acetone comes from both anthropogenic and biogenic emissions in spring, autumn and

262

Z. Jiang et al. / Environmental Pollution 253 (2019) 259e267

Table 1 Average concentration of the carbonyls, C1/C2 and C2/C3 in each season at the urban site (S1) in Changsha, China (mg/m3). Spring

Formaldehyde Acetaldehyde Acetone Propionaldehyde MACR Total C1/C2 C2/C3

Summer

Autumn

Winter

Average

Min

Max

Average

Min

Max

Average

Min

Max

Average

Min

Max

6.57 ± 2.14 3.29 ± 1.00 3.66 ± 1.10 0.67 ± 0.06 0.54 ± 0.13 14.73 ± 2.49 2.03 ± 0.38 5.76 ± 0.71

2.94 1.43 2.14 0.60 0.39 7.5

10.36 4.83 5.60 0.76 0.69 22.24

14.09 ± 5.15 8.28 ± 3.46 9.02 ± 6.42 1.28 ± 0.61 0.6 ± 0.56 33.27 ± 5.94 2.10 ± 0.97 8.67 ± 6.46

1.84 0.96 0.88 0.23 0.20 3.98

26.61 13.85 32.53 2.24 2.13 77.36

9.24 ± 3.22 5.48 ± 1.83 8.62 ± 2.00 0.73 ± 0.34 0.62 ± 0.34 24.69 ± 4.15 1.80 ± 0.70 9.51 ± 6.55

4.20 3.06 4.24 0.20 0.21 11.83

17.70 7.78 13.15 1.68 1.69 42

5.88 ± 1.81 4.84 ± 2.37 7.84 ± 3.33 0.87 ± 0.43 0.26 ± 0.05 19.69 ± 3.43 1.33 ± 0.43 6.47 ± 2.64

2.59 2.36 2.50 0.24 0.22 7.87

8.38 11.99 15.96 1.64 0.32 38.29

Table 2 Meteorological parameters in the sampling periods at the urban site (S1) in Changsha, China. Season

Date

Temperature range(
C)

RH(%)

Sunshine hours(h)

Weather

Spring Summer Autumn Winter

May 2015 JuneeJuly 2015 SeptembereNovember 2014 December 2014eJanuary2015

24e28 26e35 13e31 5e18

84.5 ± 0.7 74.8 ± 10.2 61.4 ± 14.1 53.4 ± 7.5

3.1 7 6.3 3.5

Sunny、Cloudy Sunny、Cloudy、Rain Sunny、Cloudy Sunny、Cloudy

winter. MACR was formed by the reaction of isoprene emissions with OH and O3, indicating that the acetaldehyde, acetone and MACR in the atmosphere of Changsha in summer are the same natural source. Except in spring, propionaldehyde correlated well with formaldehyde, acetaldehyde and acetone, showing that propionaldehyde and formaldehyde, acetaldehyde, and acetone have the same anthropogenic origin. The C1/C2 ratio is used to compare the results of carbonyl measurement studies at different places (Lü et al., 2010; Duan et al., 2012; Guo et al., 2016), which is generally 1e2 at urban area and about 10 in forests rural areas (Shepson and Hastie, 1991). The average C1/C2 ratio was 1.87 which is consistent with the results of the study in Guangzhou, China (1.81) (Feng et al., 2005) and Iran (Delikhoon et al., 2018). However, C1/C2 values exceeded 2 in spring and summer and much higher than that in winter, showing the positive effect of photochemical activities on improving C1/C2 ratio. A study (Ji et al., 2012) has shown that high molecular weight carbonyl compounds are more reactive and low molecular weight compounds are less reactive. High emissions occur when sunlight intensity and temperature are high and zero emission after sunset, indicating biogenic emission made great contribution to atmospheric formaldehyde during day time at the sample site. The results of the study are similar to those of Guangzhou (Lü et al., 2010). Acetaldehyde/propionaldehyde (C2/C3) has been used as another indicator of the anthropogenic source of aldehydes samples in the atmosphere, as propionaldehyde was believed to be related only to anthropogenic emissions (Ho et al., 2002). The average value of the C2/C3 ratio in this study was 8.42 ± 5.93 and higher than those heavy polluted cities like Taiwan (5.68, 2.91), Hong Kong (2.9), Beijing (6.29) (Wang et al., 2010; Cheng et al., 2014; Duan et al., 2012). This further proves the important contribution of natural factors to carbonyls. The daily variation of C1/C2 ratio (shown in Fig. 3) ranged between 1.30 and 3.08. The maximal value of 3.08 around 15:00 h (BT), when plant emissions of isoprene are highest under the strongest sun exposure and high temperatures, further indicating biogenic emission made great contribution to atmospheric formaldehyde during day time at the sampling site (Jiang et al., 2016). 3.3. Contribution of isoprene emitted from vegetable to atmospheric formaldehyde Isoprene (C5H8) is one of the most abundant biogenic VOCs

mainly produced by plants through photosynthesis, mostly from terrestrial regions. Once emitted, isoprene is quickly oxidized by atmospheric OH, and the oxidation reaction of isoprene is very complex which can produce many oxidation products, including formaldehyde (HCHO), methyl vinyl ketone (MVK), methacrolein (MACR), and numerous other oxygen-containing organics (Pang and Lee, 2010). Isoprene is one of the main biogenic VOCs in some Chinese cities (Song et al., 2007; Xie et al., 2008). There is a part of broad-leaf trees, shrubbery and lawn, and most of them are strong isoprene emitters (Pang et al., 2009). Assuming the yields of [MACR] and [MVK] produced by isoprene are 0.23 and 0.32, respectively (Atkinson, 1997). If we apply these values to the ubiquitous environmental conditions present in this measurement activity, we can obtain a rough estimate the amount of isoprene (Disoprene) that is reacted by the following equation. This method has been used in many studies (Stroud et al., 2001; Duane et al., 2002; Mu et al., 2007).

Disoprene ¼ 0:5½MACR=0:23 þ 0:5½MVK=0:32

(4)

Then, [HCHO]isoprene can be calculated by the following equation (5)

½HCHOisoprene ¼ f Disoprene ðf ¼ 0:63Þ

(5)

where f is the total fractional yield of formaldehyde from isoprene (0.63) as reported by Carter and Atkinson (1996). The relative importance of sources for atmospheric formaldehyde can be assessed by estimating the concentration of formaldehyde can be attributed to photo-oxidation of isoprene (Duane et al., 2002). In our study, MACR was measured in Changsha from May to November. MVK was not detected during the campaign possibly because the calibration standards (Supelco, USA) did not contain DNPH derivatives of MVK. Since the yield of MVK from isoprene was not determined, this equation can be written as follows:

Disoprene ¼ ½MACR=0:23

(6)

Formula (6) had been used in some previous studies (Duane et al., 2002; Mu et al., 2007; Xie et al., 2008; Pang et al., 2009; Pang and Lee, 2010). The diurnal variation of MACR, formaldehyde and temperature in Changsha is shown in Fig. 4. The similar trends among MACR, formaldehyde and air temperature indicated MACR mainly come from the photo-oxidation of isoprene released by

Z. Jiang et al. / Environmental Pollution 253 (2019) 259e267

Fig. 2. Average diurnal variations of carbonyls in each season at the urban site (S1) in Changsha, China. BT: Beijing Time.

263

264

Z. Jiang et al. / Environmental Pollution 253 (2019) 259e267

Table 3 Correlations of the carbonyls in each season at the urban site (S1) in Changsha, China (mg/m3). Season

Speices

Formaldehyde

Spring

Formaldehyde Acetaldehyde Acetone Propionaldehyde MACR Formaldehyde Acetaldehyde Acetone Propionaldehyde MACR Formaldehyde Acetaldehyde Acetone Propionaldehyde MACR Formaldehyde Acetaldehyde Acetone Propionaldehyde MACR

1.00 0.76a 0.71a 0.62 0.39 1.00 0.54a 0.15 0.25b 0.06 1.00 0.50a 0.31b 0.59a 0.13 1.00 0.73a 0.68a 0.65a 0.42

Summer

Autumn

Winter

a b

Acetaldehyde

Acetone

Propionaldehyde

MACR

1.00 0.84a 0.34 0.25

1.00 0.28 0.68

1.00 0.46

1.00

1.00 0.32a 0.68a 0.50a

1.00 0.53a 0.72a

1.00 0.70a

1.00

1.00 0.16 0.53a 0.18

1.00 0.54a 0.52a

1.00 0.09

1.00

1.00 0.67a 0.72a 0.07

1.00 0.56a 0.17

1.00 0.35

1.00

Correlation is significant at the 0.01 levels. Correlation is significant at the 0.05 levels.

Fig. 3. Daily concentration ratio variations of formaldehyde/acetaldehyde (C1/C2) measured on 18 October 2014, at urban site (S1), Changsha.

plants, and elevated by the increasing air temperature. The intensity of sunlight has a great influence on air temperature, so similar trends between concentrations of carbonyls and temperature illustrate the contribution of photochemical reactions to the atmospheric carbonyls. The amounts of formaldehyde produced by the oxidation of isoprene in mountainous city of Changsha were calculated and the results are listed in Table 4. From December 2014 to January 2015, most of the values of MACR were below the detection limit. In winter, the lower isoprene emission is due to leaf senescence, such as maple leaf. (Steinbrecher et al., 1997; Zhang et al., 2000; Pang and Lee, 2010). The monthly concentration of formaldehyde produced from isoprene accounts for 4.8%e39.1% of formaldehyde in ambient air. According to statistics from Hunan Forestry Bureau, the forest coverage rate in mountainous city of Changsha was 54.8% in 2014 and 2015. The vegetation of Changsha is dominated by subtropical broad-leaved evergreen forest, such as camphor tree. Isoprene emissions from plants contribute significantly to photo-oxidants in the urban atmosphere. The amount of isoprene emitted by plants also contributes significantly to formaldehyde concentrations in the atmosphere, ranging from 30

percent to 60 percent in May, June, July and August (Duane et al., 2002). The maximum contribution of isoprene is found between 14:00 and 16:00 in June 2015. It has to be noted that the above method is based on the crude assumption that MACR has a much longer photochemical life than isoprene (Carter and Atkinson, 1996; Atkinson, 1997). Although isoprene reacts with HO much faster than MACR, the photolysis rates of MACR and MVK are faster at noon in summer. In this case, the contribution of isoprene to HCHO may be higher than expected. 3.4. Comparison with other cities and risk assessment In this study, a comparison of the three major carbonyl concentrations with other cities is illustrated in Table 5. The levels of atmospheric carbonyls in Beijing (Pang and Mu, 2006), Shanghai (Huang et al., 2009), Guangzhou (Wang et al., 2007) and Kolkata (Dutta et al., 2009) are significantly higher than those reported in other cities. As observed in Table 5, carbonyls levels found in this study are similar to the reported of Guiyang (Pang and Lee, 2010) in winter and Iran in summer (Delikhoon et al., 2018). The average

Z. Jiang et al. / Environmental Pollution 253 (2019) 259e267

265

Fig. 4. Diurnal variations of MACR, formaldehyde and air temperature on 11 July,2015 in S1 in Changsha, China.

Table 4 Contribution of isoprene photo-oxidation to formaldehyde levels from September 2014 to July 2015 (mg/m3) in S1. The calculation is described in the text. Month

08:00e10:00 10:00e12:00 12:00e14:00 14:00e16:00 16:00e18:00 18:00e20:00 Monthly average Ambient HCHO Isoprene contribution Mean Mean Mean Mean Mean Mean

September,2014 October,2014 November,2014 December,2014 January,2015 May,2015 June,2015 July,2015

2.74 0.79 0.86 0.30 0.26 ND 4.05 0.88

1.97 1.53 0.71 0.36 0.29 0.62 3.67 1.01

1.34 2.08 0.67 ND ND 1.23 4.55 1.12

1.29 2.36 1.24 ND ND 1.81 5.20 2.63

1.18 2.44 1.44 0.25 ND 0.95 4.82 1.70

1.37 1.15 0.85 0.37 ND 0.53 4.52 1.62

1.65 1.73 0.96 0.32 0.28 1.03 4.47 1.49

9.69 10.92 6.04 6.67 5.35 6.57 11.43 11.80

17.0% 15.8% 15.9% 4.8% 5.2% 15.7% 39.1% 12.6%

Table 5 Comparisons of carbonyl concentrations to other area. (mg/m3). Locations

Formaldehyde

Acetaldehyde

Acetone

Sampling Time

Reference

Changsha, China (urban) Changsha, China (urban) Changsha, China (semi-urban) Beijing, China (urban) Guiyang, China (urban) Guangzhou, China (urban) Guangzhou, China (urban) Xi'an, China (urban) Xi'an, China (urban) Shanghai, China (urban) Hong Kong, China (urban) Monterrey, Mexico (urban) Kolkata, India (urban) Shiraz, Iran (urban)
ans, France (semi-urban) Orle Langmuir, Mexico (Forested zone)

14.09 5.88 6.28 14.8 4.8 10.5 15 5.57 7.92 19.4 5.74 7.99 23.93 15.07 3.78 2.3

8.28 4.84 4.25 10.2 5.7 8.5 10.7 12.0 3.7 15.9 1.80 14.58 18.67 8.40 1.87 1.0

9.02 7.84 9.57 16.6 5.1 e e 9.33 6.41 11.9 e e 9.97 e 4.75 1.2

JuneeJuly 2015 December 2014eJanuary 2015 December 2014eJanuary 2015 November 2004eOctober2005 December 2008eAugust 2009 December 2004eFebruary2005 JulyeSeptember 2004 January 2010 June 2009 2014e2015 2012 April 2012eMarch 2013 MarcheJune 2006 June 2017eJuly 2017 JuneeJuly 2011 1997

This work This work This work Pang and Mu (2006) Pang and Lee (2010) Wang et al. (2007) Wang et al. (2007) Dai et al. (2012) Dai et al. (2012) Huang et al. (2009) Cheng et al. (2014)
n-Breto
n et al. (2017) Cero Dutta et al. (2009) Delikhoon et al. (2018) Jiang et al. (2016) Villanueva-Fierro et al. (2004)

concentrations of carbonyl compounds in this study are lower than that in Shanghai (Huang et al., 2009), Beijing (Pang and Mu, 2006), even in foreign countries like Kolkata (Dutta et al., 2009). However, atmosphere carbonyl levels measured during this study are higher than those reported in Guiyang (Pang and Lee, 2010), Xi'an (Dai et al., 2012) and Hong Kong (Cheng et al., 2014), but significantly lower than the forest (Villanueva-Fierro et al., 2004) and semiurban (Jiang et al., 2016) atmosphere. Similar to this study, the high level of carbonyls at urban sites might be due to the

anthropogenic emissions like vehicular exhaust in Beijing (Pang and Mu, 2006) and Xi'an (Dai et al., 2012). In addition, this study sampled at Muyun Town located in semi-urban of Changsha from December 2014 to January 2015. The concentrations of the main carbonyls are much higher than that in semi-urban of France (Jiang et al., 2016), and close to the concentration levels in urban areas in Changsha. It shows that the semi-urban of Changsha is confronted with the same air pollution as the urban areas. The value of integrated lifetime cancer risk (ILTCR) and hazard

266

Z. Jiang et al. / Environmental Pollution 253 (2019) 259e267

quotient (HQ) were calculated according to the method in EPA. The ILTCR value of formaldehyde and acetaldehyde are 1.23E-04 and 1.34E-05. All of them exceeded the value of 1E-06, showing significant cancer risk (Dutta et al., 2009; Zhang et al., 2012). HQ exceeding one indicates unsafe risk (Baghani et al., 2019; Dehghani et al., 2018a,b,c; Delikhoon et al., 2018; Demirel et al., 2014; Durmusoglu et al., 2010; Hazrati et al., 2016a,b; Hazrati et al., 2015; Jalali et al., 2014; Li et al., 2014; Li et al., 2008; Moolla et al., 2015a,b; Tunsaringkarn et al., 2012). In our study, the HQ values of formaldehyde and acetaldehyde are 2.80E-01 and 1.86E-01. 4. Conclusions This study was the first to evaluates the environmental level and possible source of a series of carbonyl compounds in mountainous city of Changsha. Formaldehyde, acetaldehyde and acetone were the principal carbonyls. Seasonal variations of formaldehyde and acetaldehyde were significant, with maxima in summer time, possibly related to the large amount of vegetation in Changsha and intensive photochemical conditions. During the day, the highest concentration essentially appeared near the time points of 9:00, 13:00, and 19:00, which are peak hours of work, noon, and peak of off-duty. Good correlations between formaldehyde and acetaldehyde suggest that formaldehyde and acetaldehyde came from the same source. Except in spring, propionaldehyde correlated well with formaldehyde, acetaldehyde and acetone, showing that propionaldehyde and formaldehyde, acetaldehyde, and acetone have the same anthropogenic origin. There are Yuelu Mountain and many parks. Thus, Changsha is not a completely urbanized city and it is rich in vegetation. Both atmospheric photochemical reactions and anthropogenic sources dominate the levels of carbonyls. The dates of ILTCR was calculated, indicating there are cancer risk of formaldehyde and acetaldehyde. Conflicts of interest We declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted. Acknowledgments This work was supported by the National Natural Science Foundation of China (No. 21307008) and Changsha Science and Technology Project (No. K1403048-31). References Duan, J., Guo, S., Tan, J., Wang, S., Chai, F., 2012. Characteristics of atmospheric carbonyls during haze days in Beijing, China. Atmos. Res. 114, 17e27. Feng, Y., Wen, S., Chen, T., Wang, X., Lv, H., Bi, X., Sheng, G., Fu, J., 2005. Ambient levels of carbonyls and their sources in Guangzhou, China. Atmos. Environ. 39, 1789e1800. Ho, K.F., Lee, S.C., Louie, P.K., Zou, S.C., 2002. Seasonal variation of carbonyl compound concentrations in urban area of Hong Kong. Atmos. Environ. 36, 1259e1265. Ji, Y.M., Gao, Y.P., Li, G.Y., An, T.C., 2012. Theoretical study of the reaction mechanism and kinetics of low-molecular-weight atmospheric aldehydes (C1eC4) with NO2. Atmos. Environ. 54, 288e295. Atkinson, R., 1997. Gas-phase tropospheric chemistry of volatile organic compounds: a review. Atmos. Environ. 37, 197e219. Atkinson, R., 2000. Atmospheric chemistry of VOCs and NOx. Atmos. Environ. 34 (12e14), 2063e2101. Baghani, A.N., Sorooshian, A., Heydari, M., Sheikhi, R., Golbaz, S., Ashournejad, Q., Kermani, M., Golkhorshidi, F., Barkhordari, A., Jafari, A.J., Delikhoon, M., Shahsavani, A., 2019. A case study of BTEX characteristics and health effects by major point sources of pollution during winter in Iran. Environ. Pollut. 247, 607e617. Borbon, A., Locoge, N., Veillerot, M., Galloo, J.C., Guilermo, R., 2002. Characterisation of NMHCs in a French urban atmosphere: overview of the main sources. Sci.

Total Environ. 292, 177e191. Carlier, P., Hannachi, H., Mouvier, G., 1986. The chemistry of carbonyl compounds in the atmosphere. Atmos. Environ. 20, 2079e2099. Carter, W.P.L., Atkinson, R., 1996. Development and evaluation of a detailed mechanism for the atmospheric reactions of isoprene and NOx. Int. J. Chem. Kinet. 28, 497e530.
n, R.M., Cero
n, J.G., Muriel, M., 2007. Diurnal and seasonal trend in carbonyl Cero levels in a semi-urban coastal site in the Gulf of Campeche, Mexico. Atmos. Environ. 41, 63e71.
n-Breto
n, J.G., Cero
n-Breto
n, R.M., Kahl, J.D.W., Ramírez-Lara, E., AguilarCero
n, C.A., Montalvo-Romero, C., Mendoza-Dominguez, A., Muriel-García, M., Uca Ortínez-Alvarez, J.A., 2017. Carbonyls in the urban atmosphere of Monterrey, Mexico: sources, exposure, and health risk. Air Qual. Atmos. Health 10, 53e67. Chen, W.T., Shao, M., Ming, W., Lu, S.H., Liu, Y., Yuan, B., Yang, Y.D., Zeng, L.M., Chen, Z.M., Chang, C.C., Zhang, Q., Hu, M., 2016. Variation of ambient carbonyl levels in urban Beijing between 2005 and 2012. Atmos. Environ. 129, 105e113. Cheng, Y., Lee, S.C., Huang, Y., Ho, K.F., Ho, S.S.H., Yau, P.S., Louie, P.K.K., Zhang, R.J., 2014. Diurnal and seasonal trends of carbonyl compounds in roadside, urban, and suburban environment of Hong Kong. Atmos. Environ. 89, 43e51. Dai, W.T., Ho, S.S.H., Ho, K.F., Liu, W.D., Cao, J.J., Lee, S.C., 2012. Seasonal and diurnal variations of mono- and di-carbonyls in Xi'an, China. Atmos. Res. 113, 102e112. Dehghani, F., Golbabaei, F., Abolfazl Zakerian, S., Omidi, F., Mansournia, M.A., 2018a. Health risk assessment of exposure to volatile organic compounds (BTEX) in a painting unit of an automotive industry. Health Saf. Work 8, 55e64. Dehghani, M., Fazlzadeh, M., Sorooshian, A., Tabatabaee, H., Miri, M., Baghani, A., Delikhoon, M., Mahvi, A., Rashidi, M., 2018b. Characteristics and health effects of BTEX in a hot spot for urban pollution. Ecotoxicol. Environ. Saf. 155, 133. Dehghani, M., Fazlzadeh, M., Sorooshian, A., Tabatabaee, H.R., Miri, M., Baghani, A.N., Delikhoon, M., Mahvi, A.H., Rashidi, M., 2018c. Characteristics and health effects of BTEX in a hot spot for urban pollution. Ecotoxicol. Environ. Saf. 155, 133e143. Delikhoon, M., Fazlzadeh, M., Sorooshian, A., Baghani, A.N., Golaki, M., Ashournejad, Q., Barkhordari, A., 2018. Characteristics and health effects of formaldehyde and acetaldehyde in an urban area in Iran. Environmental Pollution 242, 938e951. € € Do €geroglu, T., Gaga, E.O., 2014. Personal exposure of primary Demirel, G., Ozden, O., school children to BTEX, NO2 and ozone in Eskisehir. Turkey: Relationship with indoor/outdoor concentrations and risk assessment. J.Sci. Total Environ. 473, 537e548. Duane, M., Poma, B., Rembges, D., Astorga, C., Larsen, B.R., 2002. Isoprene and its degradation products as strong ozone precursors in Insubria, Northern Italy. Atmos. Environ. 36, 3867e3879. Durmusoglu, E., Taspinar, F., Karademir, A.J., 2010. Health Risk Assessment of BTEX Emissions in the Landfill Environment. J. Hazard Mater. 176, 870e877. Dutta, C., Som, D., Chatterjee, A., Mukherjee, A.K., Jana, T.K., Sen, S., 2009. Mixing ratios of carbonyls and BTEX in ambient air of Kolkata, India and their associated health risk. Environ. Monit. Assess. 148, 97e107. Guo, S., Wen, S., Wang, X., Sheng, G., Fu, J., Hu, P., Yu, Y., 2009. Carbon isotope analysis for source identification of atmospheric formaldehyde and acetaldehyde in Dinghushan Biosphere Reserve in South China. Atmos. Environ. 43, 3489e3495. Guo, S.J., Chen, M., Tan, J.H., 2016. Seasonal and diurnal characteristics of atmospheric carbonyls in Nanning, China. Atmos. Res. 169, 46e53.
s: Hazrati, S., Rostami, R., Fazlzadeh, M., 2015. BTEX in Indoor Air of Waterpipe Cafe Levels and Factors Influencing Their Concentrations. J. Sci. Total Environ. 524, 347e353. Hazrati, S., Rostami, R., Farjaminezhad, M., Fazlzadeh, M., 2016a. Preliminary Assessment of BTEX Concentrations in Indoor Air of Residential Buildings and Atmospheric Ambient Air in Ardabil, Iran. J. Atmos. Environ. 132, 91e97. Hazrati, S., Rostami, R., Fazlzadeh, M., Pourfarzi, F., 2016b. Benzene, toluene, ethylbenzene and xylene concentrations in atmospheric ambient air of gasoline and CNG refueling stations. Air Quality, Atmosphere & Health 9, 403e409. Huang, J., Feng, Y.L., Xiong, B., Fu, J.M., Sheng, G.Y., 2009. Ambient levels of carbonyl compounds in Shanghai, China. Environ. Sci. 30, 2701e2706. Jalali, M., Jalali, S., Shafii Motlagh, M., Mardi, H., Negahban, S.A.R., Faraji Tomarkandi, V., Jahangiri, M., 2014. Health Risk Assessment of Occupational Exposure to BTEX Compounds in Petrol Refueling Stations in Mashhad. J. Neyshabur Univ. Med. Sci. 1, 19e27. €le, Ve
ronique, Mellouki, Abdelwahid, Mu, Y.J., 2016. Jiang, Z.H., Grosselin, Benoît, Dae Seasonal, diurnal and nocturnal variations of carbonyl compounds in the semi
ans, France. Environ. Sci. 40, 84e91. urban environment of Orle Karakitsios, S., Asikainen, A., Garden, C., Semple, S., Brouwere, K.D., Galea, K.S.,
nchez-Jime
nez, A., Gotti, A., Jantunen, M., Sarigiannis, D., 2014. Integrated Sa exposure for risk assessment in indoor environments based on a review of concentration data on airborne chemical pollutants in domestic environments in Europe. Indoor Built Environ. 24, 1110e1146. Kean, A.J., Grosjean, E., Grosjean, D., Harley, R.A., 2001. On-road measurement of car- bonyls in California light-duty vehicle emissions. Environ. Sci. Technol. 35, 4198e4204. Kim, K.H., Hong, Y.J., Pal, R., Jeon, E.C., Koo, Y.S., Sunwoo, Y., 2008. Investigation of carbonyl compounds in air from various industrial emission sources. Chemosphere 70, 807e820. Li, T.-T., Liu, Z.-R., Bai, Y.-H., 2008. Human Cancer Risk from the Inhalation of Formaldehyde in Different Indoor Environments in Guiyang City. J. Bull. Environ. Contam. Toxicol. 81, 200e204.

Z. Jiang et al. / Environmental Pollution 253 (2019) 259e267 Li, L., Li, H., Zhang, X., Wang, L., Xu, L., Wang, X., Yu, Y., Zhang, Y., Cao, G.J., 2014. Pollution Characteristics and Health Risk Assessment of Benzene Ho- mologues in Ambient Air in the Northeastern Urban Area of Beijing. J. Environ. Sci. 26, 214e223. Louis, J.S., Hanwant, B.S., 1986. Measurements of formaldehyde and acetaldehyde in the urban ambient air. Atmos. Environ. 20 (6), 1301e1304. Lü, H.X., Cai, Q.Y., Wen, S., Chi, Y.G., Guo, S.J., Sheng, G.Y., Fu, J.M., 2010. Seasonal and diurnal variations of carbonyl compounds in the urban atmosphere of Guangzhou, China. Sci. Total Environ. 408, 3523e3529. Moolla, R., Curtis, C.J., Knight, J., 2015a. Assessment of occupational exposure to BTEX compounds at a bus diesel-refueling bay: a case study in Johannesburg, South Africa. Sci. Total Environ. 537, 51e57. Moolla, R., Curtis, C.J., Knight, J., 2015b. Occupational exposure of diesel station workers to BTEX compounds at a bus depot. Int. J. Environ. Res. Publ. Health 12, 4101e4115. Moussa, S.G., El-Fadel, M., Saliba, N.A., 2006. Seasonal, diurnal and nocturnal behaviors of lower carbonyl compounds in the urban environment of Beirut, Lebanon. Atmos. Environ. 40, 2459e2468. Mu, Y.J., Pang, X.B., Quan, J.N., Zhang, X.S., 2007. Atmospheric carbonyl compounds in Chinese background area: a remote mountain of the Qinghai-Tibetan Plateau. J. Geophys. Res. 112, D22302. https://doi.org/10.1029/2006JD008211. Pang, X.B., Lee, X., 2010. Temporal variations of atmospheric carbonyls in urban ambient air and street canyons of a Mountainous city in Southwest China. Atmos. Environ. 44, 2098e2106. Pang, X.B., Mu, Y.J., 2006. Seasonal and diurnal variations of carbonyl compounds in Beijing ambient air. Atmos. Environ. 40, 6313e6320. Pang, X.B., Mu, Y.J., Zhang, Y., Lee, X., 2009. Contribution of isoprene to formaldehyde and ozone formation based on its oxidation products measurement in Beijing, China. Atmos. Environ. 43, 2142e2147. Possanzini, M., Di, P.V., Preticca, M., Fratarcangeli, R., Brocco, D., 1996. Measurements of lower carbonyls in Rome ambient air. Atmos. Environ. 30, 3757e3764. Sarigiannis, D.A., Karakitsios, S.P., Gotti, A., Liakos, I.L., Katsoyiannis, A., 2011. Exposure to major volatile organic compounds and carbonyls in European indoor environments and associated health risk. Environ. Int. 37, 743e765. Seco, R., Peneuelas, J., Filellaet, I., 2007. Short-chain oxygenated VOCs: emission and uptake by plants and atmospheric sources, sinks, and concentrations. Atmos. Environ. 41, 2477e2499. Shepson, P.B., Hastie, D.R., 1991. Atmospheric concentrations and temporal variations of C1~C3 carbonyl compounds at two rural sites in central Ontario. Atmos. Environ. 25, 2001e2005. Singh, H.B., Chen, Y., Tabazadeh, A., Fukui, T., Bey, I., Yantosca, R., Jacob, D., Arnold, F., Wohlfrom, K., Atlas, E., Flocke, F., Blake, D.N., Heikes, B., Snow, J., Talbot, R.,

267

Gregory, G., Sachse, G., Vay, S., Kondo, Y., 2000. Distribution and fate of select oxygenated organic species in the troposphere and lower stratosphere over the Atlantic. J. Geophys. Res. 105, 3795e3805. €dter, G., Fehsenfeld, U., Gabriel, R., Kolb, C., Steinbrecher, R., Ziegler, H., Eichsta €nwitz, R., Schürmann, W., 1997. Monoterpene and isoprene Rabong, R., Scho emission in Norway spruce forests. In: Slanina, S. (Ed.), Biosphere-Atmosphere Exchange of Pollutants and Trace Substances. Springer-Verlag, Berlin, pp. 352e365. Song, Y., Shao, M., Liu, Y., Lu, S., Kuster, W., Goldan, P., Xie, S., 2007. Source Apportionment of ambient volatile organic compounds in Beijing. Environ. Sci. Technol. 41, 4348e4353. Stroud, C.A., Roberts, J.M., Goldan, P.D., et al., 2001. Isoprene and its oxidation products, methacrolein and methylvinyl ketone, at an urban forested site during the 1999 Southern Oxidants Study. J. Geophys. Res. 106, 8035e8046. Tunsaringkarn, T., Siriwong, W., Rungsiyothin, A., Nopparatbundit, S., 2012. Occupational exposure of gasoline station workers to BTEX compounds in Bangkok, Thailand. Int. J. Occup. Environ. Med. 3. US EPA (US Environmental Protection Agency), 1999. Method TO-11 A. Determination of Formaldehyde in Ambient Air Using Adsorbent Cartridge Followed by High Performance Liquid Chromatography (HPLC). Active Sampling Methodology, Research Triangle Park, NC, USA. Villanueva-Fierro, I., Popp, C.J., Martin, R.S., 2004. Biogenic emissions and ambient concentrations of hydrocarbons carbonyl compounds and organic acids from ponderosa pine and cottonwood trees at rural and forested sites in Central New Mexico. Atmos. Environ. 38 (2), 249e260. Wang, B., Lee, S.C., Ho, K.F., 2007. Characteristics of carbonyls: concentrations and source strengths for indoor and outdoor residential microenvironments in China. Atmos. Environ. 41, 2851e2861. Wang, H.K., Huang, C.H., Chen, K.S., Peng, Y.P., Lai, C.H., 2010. Measurement and source characteristics of carbonyl compounds in the atmosphere in Kaohsiung city, Taiwan. J. Hazard Mater. 179, 1115e1121. Xie, X., Shao, M., Liu, Y., Lu, S., Chang, C.-C., Chen, Z.-M., 2008. Estimate of initial isoprene contribution to ozone formation potential in Beijing, China. Atmos. Environ. 42, 6000e6010. Xu, Z., Liu, J.F., Zhang, Y.J., Liang, P., Mu, Y.J., 2010. Ambient levels of atmospheric carbonyls in Beijing during the 2008 olympic games. J. Environ. Sci. 22, 1348e1356. Zhang, X., Mu, Y., Song, W., Zhuang, Y., 2000. Seasonal variations of isoprene emissions from deciduous trees. Atmos. Environ. 34, 3027e3032. Zhang, Y.J., Mu, Y.J., Liu, J.F., Mellouki, A., 2012. Levels, source and health risks of carbonyls and BTEX in the ambient air of Beijing, China. J. Environ. Sci. 24 (1), 124e130.