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Particle size distributions of currently used pesticides in ambient air of an agricultural Mediterranean area
Atmospheric Environment 95 (2014) 29e35
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Atmospheric Environment journal homepage: www.elsevier.com/locate/atmosenv
Particle size distributions of currently used pesticides in ambient air of an agricultural Mediterranean area a, d, *, Amalia Mun ~ oz b, d, Esther Borra s b, d, Teresa Vera b, d, Clara Coscolla a, c, d denas b, d, Vicent Yusa Milagros Ro a
Public Health Laboratory of Valencia-FISABIO, 21, Avenida Catalunya, 46020 Valencia, Spain neo (CEAM), 14, Charles Robert Darwin, P. Tec. Paterna, 46980 Valencia, Spain n Centro de Estudios Ambientales del Mediterra Fundacio ~ oz, Dr. Moliner 50, 46100 Burjassot, Spain Analytical Chemistry Department, University of Valencia, Edifici Jeroni Mun d Atmospheric Pesticide Research Group of Valencia, Spain b c
h i g h l i g h t s Particle size distribution of pesticides in Mediterranean agriculture was studied. Pesticides accumulated in the ultrafine-fine and coarse particle size fractions. The total concentrations in the particulate phase ranged from 3.5 to 383.1 pg m3.
a r t i c l e i n f o
a b s t r a c t
Article history: Received 11 February 2014 Received in revised form 5 June 2014 Accepted 10 June 2014 Available online 10 June 2014
This work presents first data on the particle size distribution of 16 pesticides currently used in Mediterranean agriculture in the atmosphere. Particulate matter air samples were collected using a cascade impactor distributed into four size fractions in a rural site of Valencia Region, during July to September in 2012 and from May to July in 2013. A total of 16 pesticides were detected, including six fungicides, seven insecticides and three herbicides. The total concentrations in the particulate phase (TSP: Total Suspended Particulate) ranged from 3.5 to 383.1 pg m3. Most of the pesticides (such as carbendazim, tebuconazole, chlorpyrifos-ethyl and chlorpyrifos-methyl) were accumulated in the ultrafine-fine (<1 mm) and coarse (2.5e10 mm) particle size fractions. Others like omethoate, dimethoate and malathion were presented only in the ultrafine-fine size fraction (<1 mm). Finally, diuron, diphenylamine and terbuthylazinedesethyl-2-OH also show a bimodal distribution but mainly in the coarse size fractions. © 2014 Elsevier Ltd. All rights reserved.
Keywords: Pesticide Size distribution Atmospheric concentrations
1. Introduction The particle size distribution affects the particulate matter's transport in air, the dry or wet deposition from the atmosphere onto natural surfaces and the deposition in the human lungs. So, information about the particle size distribution of organic compounds is vital in order to estimate their inputs into the ecosystems and the human health (Wu et al., 2006; Chrysikou et al., 2009) . Small particles penetrate in the respiratory system, and cause direct health impact (Chrysikou and Samara, 2009). Therefore, particle size distribution of organic pollutants such as n-alkanes, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polychlorinated
* Corresponding author. Public Health Laboratory of Valencia-FISABIO, 21, Avenida Catalunya, 46020 Valencia, Spain. E-mail address: [email protected] (C. Coscoll a). http://dx.doi.org/10.1016/j.atmosenv.2014.06.022 1352-2310/© 2014 Elsevier Ltd. All rights reserved.
dibenzo-p-dioxins, dibenzofurans and metals has been repeatedly studied in several areas around the world (Bi et al., 2005; Allen et al., 1996; Duan et al., 2007; Chrysikou et al., 2009; Oh et al., 2002; Chao et al., 2003; Zereini et al., 2005). However, to our knowledge, only one study have been published related with par ticle size distribution of currently used pesticides (CUPs) (Coscolla et al., 2013a). Semivolatile organic compounds (SVOCs) can be bound to particles with different particle size distribution. Particles can be divided roughly into modes. The nucleation (or nuclei) mode comprises particles with diameters up to 0.01 mm. The Aitken mode spans the size range from about 0.01 mm to 0.1 mm diameter. These two modes account for the preponderance of particles by number; because of their small size, these particles rarely account for more than a few percent of the total mass of airborne particles. The accumulation mode, extending from 0.1 to 2.5 mm, usually accounts
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et al. / Atmospheric Environment 95 (2014) 29e35 C. Coscolla
for most of the aerosol surface area and a substantial part of the aerosol mass. The accumulation mode is so named because particle removal mechanisms are least efficient in this regime, causing particles to accumulate there. The coarse mode, from >2.5 mm in diameter, is formed by mechanical processes and usually consists of human-made and natural dust particles. Coarse particles have sufficiently large sedimentation velocities that they settle out of the atmosphere in a reasonable short time (Seinfeld and Pandis, 2006). Fig. 1 a shows the emission sources throughout CUPs can reach the atmosphere and the processes that permit their distribution in the different particle size fractions. There are three different emission sources during or after pesticide application in agricultural practices. Firstly, “spray drift” occurs during its application. A fraction of the dosage e 20e30% (Van de Berg et al., 1999) e applied to the target area could be deposited onto the adjacent non-target areas and another fraction can be lost in the atmosphere (Hilz and Vermeer, 2013). Secondly, volatilization is a post-application emission from soil and plants. It can happen some days or weeks after application (Bedos et al., 2002a). Thirdly, wind erosion of soil particles containing sorbed pesticides represent further significant pesticide input into the troposphere for several days or weeks after application (Voutsas et al., 2005). In addition, processes (see Fig. 1b) throughout pesticides are distributed in the three particle size fraction such as ultrafine, fine and coarse basically depend on the
following factors: the primary emission, the gas to particle distribution (G/P distribution) of the pesticide and the particle transformation by different pathways (Bedos et al., 2002b; Voutsas et al., 2005). Transformation in size occurs by different routes. Growth of particles can correspond to an increase of the mean particle size or shifting of parts of the distribution to larger sizes. Pesticides accumulated in ultrafine can shift to fine size fraction. Small pesticide particles and gaseous pesticides originate from emission sources (primary emissions) can be accumulated in ultrafine fraction. They can growth by coagulation or vapour condensation and then move to be associated in the fine particle size fraction (Venkataraman and Friedlander, 1994). Moreover, pesticides accumulated in the fine size fraction can shift to the coarse fraction. Freshly emitted pesticides can be adsorbed mainly to fine aerosol and they can become associated with coarse particles by volatilization from fine particles followed by condensation onto coarse particles (Bi et al., 2005; Duan et al., 2007). Research concerning the size distribution of particle-bound organochlorine pesticides (OCPs) in the atmosphere of Thessaloniki (Greece) has shown strong accumulation in the submicron size fraction. OCPs are known to be toxic to humans and many organisms, and are considered widespread environmental contaminants (Chrysikou and Samara, 2009). Moreover, currently used pesticides
Fig. 1. Sources and processes involved in the distribution of pesticides in the particle size fractions (G/P distribution ¼ gas to particle distribution).
et al. / Atmospheric Environment 95 (2014) 29e35 C. Coscolla
(CUPs) are the newly pesticides which are nowadays applied in the agricultural practices and are approved by EU regulations (CEU, 1991). In a recent previous study, we presented first data on the particle size distributions of current-used pesticides. This study was focused on pesticides applied to arable crops in an agricultural Continental area. In that study, most pesticides were accumulated in the fine particle size fraction (Coscoll a et al., 2013a). The main objective of this work is to study the size particle distribution of different currently used pesticides in the ambient air of an agricultural Mediterranean region. To our knowledge, this study represents the first investigation for particle size distribution of CUPs applied to Mediterranean agriculture. 2. Experimental 2.1. Pesticide selection Eighty-two pesticides and metabolites were studied which were all CUPs. CUPs approved by the EU regulations were applied mainly into citrus crops but also in other crops in the surrounded area during the sampling period. Pesticide selection was based mainly on pesticide amount applied in the region. Tables SD-1.1 and SD-1.2 show some characteristics of the studied pesticides. 2.2. Sampling and site characterization Sampling was undertaken at one sampling site located in Valencia Region, Spain. The station was placed in a rural area in the centre of the Valencia region, approximately 1 km from the city of Alzira (0 270 _2800 W, 39 090 _0000 N). Alzira has 42,543 inhabitants and is situated 43 km from Valencia city. It has in its vicinity many citrus groves such as orange trees. Samples were collected about 3 m above ground level. A Gravimetric Impactor was used for the measurement of atmospheric aerosols size distribution. DLPI Impactor (Dekati, Tampere, Finland) is a 4-stage cascade impactor and it measures gravimetric particle size distribution. Size fractions were as follows: <1 mm, 2.5e1 mm, 10e2.5 mm and >10 mm. Particles were collected on 25 and 47-mm-diameter glass fibre filters (GFFs) during one week with an average flow rate of 30 L min1. The total volume collected was around 300 m3 (see Table SD-2). A total of 16 samples were collected, randomly during weekdays. Samples were collected from July to September in 2012 (8 weeks) and from May to July in 2013 (8 weeks). These sampling weeks are the most relevant period for pesticide application. Prior to exposition, filters were baked for 24 h at 130 C to eliminate organics. To determine the weight of particulate matter (PM) accumulated during one-week exposition of filters, a Metter Toledo MX5 microbalance from (Bedford, MA, USA) was used. Filters were previously conditioned according to European standard sampling regulations (EN 12341:1998), at temperature 20 ± 1 C and at relative humidity 50 ± 5 C for at least 48 h, and then weighed. PM for each size fraction was measured weighting each filter after one week of exposure. TSP (Total Suspended Particulate) was calculated as the sum of the four size fractions. 2.3. Sample analysis The experimental work of this study was based on methods previously published. In short, pesticides were extracted from filters using ethyl acetate and microwave assisted extraction (MAE) and were subsequently detected using an LCeMS/MS system consisting of a high performance liquid chromatograph (HPLC) and TSQ , CA, USA). Electrospray Quantum Ultra mass spectrometer (San Jose ionization (ESI) and selected reaction monitoring mode (SRM) were
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et al., 2009). The transitions and used for all analytes (Coscolla limits of quantification for these analytes can be found in Table SD3. In the case of GCeMS/MS amenable pesticides, the method includes extraction of PM10-bound pesticides by microwave-assisted extraction (MAE) followed by gel-permeation chromatography (GPC) clean-up and determination by GCeMS/MS. Chromatographic analyses were performed on a Trace GC Ultra and Triplus autosampler coupled to a triple quadrupole mass spectrometer , CA, USA). The from Thermo-Finningan (TSQ Quantum GC, San Jose mass spectrometer was operated in electron impact mode (EI). Selected reaction monitoring mode (SRM) was used for all analytes et al., 2011). Table SD-4 shows some selected GCeMS/MS (Coscolla parameters and the limits of quantification for each pesticide. 2.4. Quality control protocol Each set of samples was analysed using quality assurance protocols. In order to determine the possibility of background pollution, blank filters were routinely deployed in the field to determine any contamination during sample handling. No pesticides were detected (
Table 1 Concentration (mean ± SD)a of particle-bound pesticides during the sampling period (2012e2013). Pesticides
Carbendazim Terbuthylazine Metalaxyl Tebuconazole Omethoate Terbuthylazine desethyl-2-OH Dimethoate Diuron Diphenylamine Chlorpyrifos-e Chlorpyrifos-m Trifluralin Folpet Malathion Penconazole Diazinon
Total concentration Total concentration PM 10 concentration 2012 (pg m3) 2013 (pg m3) 2010 (pg m3) (N ¼ 8)
(N ¼ 8)
138 ± 7 39 ± 5 4 32 ± 8 e 383 ± 190
75 23 e e 6 129
e 53 ± 12 104 ± 13 24 ± 3 e e e e 3.54 e
4 82 e 141 35 27 39 10 16 22
± 11 ±3
±2 ± 18 ±1 ±4 ± ± ± ± ± ± ±
33 1 1 1 5 1 1
(N ¼ 232)b,c 59.7 118.1 39.1 10 141.2 48.9 45.1 e 6.1 14.5 7.3 e 45.6 13.8 e 20.8
PM Total Suspended Particulate ¼ 10e19 mm m3. N ¼ Number of total samples. PM: Particulate matter. a The mean concentration was calculated from samples with concentration above LOQ. b Hart et al., 2012. c Coscoll a et al., 2013a,b.
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particulate phase. Nine pesticides were found during the sampling period in 2012 (see Table 1). Fungicides (carbendazim, metalaxyl, tebuconazole, diphenylamine and penconazole) were presented in concentrations ranging from 3.54 to 138 pg m3. Insecticides (diphenylamine and chlorpyrifos-e) were detected with total concentrations of 104 pg m3 and 24 pg m3, respectively. Herbicides (diuron and terbuthylazine and its metabolites) presented concentrations from 39 to 383 pg m3. Except for diphenylamine, these CUPs were authorized for the treatment of different crops mainly citrus groves by the European Union. In the case of diphenylamine, its presence could be linked with an illegal use. Most of the detected pesticides presented a high volatility (>101 Pa). Other pesticides such as carbendazim, diuron and tebuconazole have medium volatility (103e105 Pa). They also have atmospheric life (DT50) of few hours (Tables SD-1.1 and 1.2). The levels of pesticides in the atmosphere depend not only on its volatility or its atmospheric half-life, but also on their usage and the et al., conditions of the applications in the studied area (Coscolla 2010). SVOCs can be distributed between the gas and particulate phases (G/P) in the atmosphere. This distribution has been described according to different models. The octanoleair partitioning coefficient (Koa) has been proposed (Finizio et al., 1997; Harner and Bidleman, 1998; Sofuoglu et al., 2004) as a good descriptor of the absorption of SOCs to aerosols, and consequently it seems a useful predictor for the G/P partitioning of some organic pollutants. Following this theoretical model, some detected pesticides such as carbendazim, diuron and tebuconazole (Koa >10) are expected to be found mainly in the particle phase in a percentage higher than 50%. The other detected pesticides should be present mainly in the gaseous phase; the model predicts the partition for these CUPs in the particle phase ranging from 1 to 49%. Consequently, the detection of pesticides in the particulate phase for these pesticides in our study could be linked with their high usage in the studied area, and to the fact that sampling coincides to the application period of pesticides. Fungicides (metalaxyl and penconazole) were applied extensively for the treatment of different crops during the sampling period in Alzira site. Metalaxyl was used for the treatment of citrus fruit (Phytophthora spp.), vineyards (Plasmopara vitícola) and different vegetables such as potatoes, cauliflower, lettuce and peppers (Mildiu, Bremia lactucae and Phytophthora capsici). Chlorpyrifos-e insecticide is a broad-spectrum pesticide used in Valencia Region to treat different pests in almost all crops, mainly citrus fruit. Terbuthylazine herbicide is used on citrus, olive trees and fruit treatments in the area. Table 1 also presents a total number of 13 compounds detected during the sampling period in 2013. Carbendazim, terbuthylazine and its metabolite, diuron, chlorpyrifos-e and penconazole were observed during two-year study. Only diuron (82 pg m3), penconazole (16 pg m3) and chlorpyrifos-e (141 pg m3) presented lower concentrations in 2013. Five insecticides (omethoate, dimethoate, chlorpyrifos-m, malathion and diazinon), one fungicide (folpet) and one herbicide (trifluralin) were detected only during year 2013. Insecticides were presented in concentrations ranging from 4 to 35 pg m3. The fungicide was detected with total concentration of 39 pg m3. The unique herbicide detected this year was found with 27 pg m3. Except for omethoate, trifluralin and diazinon, these CUPs were authorized for the treatment of different crops mainly citrus groves by the European Union. In the case of omethoate, it is important to note that it has been banned in the European Union since 2003. Its detection is not probably related with an illegal use, but due to the fact that omethoate is a transformation product from dimethoate (Avino et al., 2011). The atmospheric oxidation of dimethoate is
likely that leads to the formation of the corresponding oxon (omethoate) similarly to the reaction channel of degradation of ~ oz et al., 2011a). Trifluralin and diazinon chlorpyrifos methyl (Mun are currently banned in the European Union, and taking into account that the atmospheric lifetime in gas-phase of these compounds are 15 min and 4 h respectively (Le Person et al., 2007; ~ oz et al., 2011b) it is suggested a possible illegal use of these Mun pesticides. All pesticides detected only in year 2013 also presented a high volatility (>101 Pa), except for folpet (2.1 102 Pa), which have medium volatility. They also have atmospheric life (DT50) of few hours (Tables SD-1.1 and 1.2). Following the theoretical model proposed by Harner and Bidleman (1998), omethoate (Koa ¼ 11) is expected to be found mainly in the particle phase in a high percentage (91%). However, the other detected pesticides (dimethoate, chlorpyrifos-m, trifluralin, folpet, malathion and diazinon) should be present mainly in the gaseous phase. The model predicts the partition for these CUPs in the particle phase ranging from 1 to 13%. Consequently, the detection of pesticides in the particulate phase for these pesticides in our study could be linked with their high usage in the studied area, and to the fact that sampling coincides to the application period of pesticides. Dimethoate is applied extensively in citrus fruit and olives. This insecticide is used against the olive fly (Bactrocera oleae) and is also used on citrus fruit plagued with aphids (Aphis sp., Toxoptera aurantii) in Alzira site. Chlorpyrifos-m and malathion are used in citrus fruit, fruit and grape in the studied area. Trifluralin is a herbicide used on soil prior to emergence of the desired plant to control annual grasses and broad-leaved weeds. Folpet is applied to the treatment of fruits and grapes. Diazinon is an organophosphate insecticide that was applied in the studied region for pest treatment of citrus fruit (Planococcus citri, Ectomyelois ceratoniae, Cryptoblabes gnidiella and ants), stone, and nugget fruits (Quadraspidiotus perniciosus). Two previous studies in the same sampling site (Alzira station) et al., 2013b; Hart et al., 2012) detected during 2010 (Coscolla similar pesticides as the present study, but samples were collected from January to December 2010. PM10 samples were collected using a high volume sampler and the sampling flow was 30 m3 h1 for 24 h, giving a total volume of filtered air around 720 m3. No temporal variations in pesticide air concentrations were observed for some pesticides such as diazinon, folpet and malathion. However, some differences during this period 2010e2013 should be stressed. A slight decline in the levels has been observed in the present study for pesticides such as terbuthylazine, metalaxyl, dimethoate and omethoate. On the other hand, for tebuconazole, diphenylamine and chlorpyrifos-m a slight increase has been observed. 3.2. Size distribution concentration using cascade-impactor The aerodynamic diameter (a.d.) of aerosol particles span over four orders of magnitude, from a few nanometres to around 100 mm. From the point of view of health effects, the size categories are defined as: ultrafine particles, smaller than about 0.1 mm in a.d; fine particles, smaller than 1 mm a.d; and coarse particles larger than 1 mm a.d. (Health Effects Institute, 2002). Out of the 82 pesticides studied in the different particle size fractions, only sixteen pesticides were detected at least in one sample (see Table 2). The particle size distribution of some of these pesticides is presented in Fig. 2. Three types of distribution were found as follows: unimodal ultrafine-fine (UFeF), bimodal (UFeF/ coarse) and mainly bimodal coarse distribution. A usual approach for studying the distribution of pollutants in the different size fractions is to use normalized histograms representing dC/dlogDp vs. Dp, where dC is the concentration of
et al. / Atmospheric Environment 95 (2014) 29e35 C. Coscolla
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Table 2 Concentration (mean ± SD)a,b and frequency of detection of particle-bound pesticides in ultrafine, fine and coarse size ranges during the sampling period (2012e2013). Pesticides
Size fraction <1 mm (PM: 6e10 mm m3)
Carbendazim Terbuthylazine Tebuconazole Omethoate Dimethoate Diuron Diphenylamine Chlorpiryfos-e Chlorpiryfos-m Penconazole Trifluralin Folpet Malathion Diazinon Terbuthylazine desethyl-2-OH Metalaxyl
1e2.5 mm (PM: 2e5 mm m3)
2.5e10 mm (PM: 2e3 mm m3)
>10 mm (PM: up 1 mm m3)
Concentration (pg m3)
Frequency of detection (%)
Concentration (pg m3)
Frequency of detection (%)
Concentration (pg m3)
Frequency of detection (%)
Concentration (pg m3)
Frequency of detection (%)
28 ± 18 13 ± 10 16 ± 11 5±2 4±1 17 ± 12 38 ± 26 50 ± 49 9±1 6±3 0 10 ± 1 10 ± 5 11 221 ± 220 4
94 75 25 19 12 19 12 81 25 12 e 37 25 6 44 6
13 ± 8 5±4 0 0 0 19 ± 17 13 ± 12 15 ± 13 9±1 0 8 10 0 11 55 ± 30 e
56 50 6 e e 19 12 69 12 e 6 6 e 6 12 e
15 ± 10 8±6 9±6 0 0 25 ± 2 35 16 ± 12 8±1 0 9±1 9 0 0 e e
50 56 12 e e 31 6 56 12 e 12 6 e e e e
9±5 7±5 0 0 0 18 ± 9 17 ± 16 12 ± 11 9 8 10 10 0 0 52 ± 50 e
25 44 e e e 31 12 62 6 12 6 6 e e 12 e
PM: Particulate matter. PMTotal Suspended Particulate ¼ 10e19 mm m3. a Number of total samples: 16. b The mean concentration and frequency of detection was calculated from samples with concentration above LOQ.
pesticides in each size fraction; and Dp is the aerodynamic diameter (Chrysikou et al., 2009). Omethoate, dimethoate and malathion presented an unimodal distribution in the ultrafine-fine size fraction (<1 mm). On the other hand, carbendazim, tebuconazole, chlorpyrifos-e and chlorpyrifosm presented a basically bimodal pesticide size distribution with peaks on the ultrafine-fine (<1 mm) and coarse (2.5e10 mm) fractions. However, diuron, diphenylamine and terbuthylazinedesethyl-2-OH also shows a bimodal distribution but in the coarse size fraction (2.5e10 and >10 mm) (see Fig. 2). The presence of some pesticides in the ultrafine-fine fraction (carbendazim, tebuconazole, chlorpyrifos-e, chlorpyrifos-m, omethoate, dimethoate, malathion) could be mainly linked to freshly emitted pesticides as primary ultrafine aerosols, and vapour condensation in this fraction. Mechanisms which contribute to pesticides distributed in particle fine size fraction, as is the case of these pesticides, are primary emissions as fine aerosols, adsorption of gas emitted pesticides to fine particles present in the atmosphere (higher surface area) and coagulation of ultrafine to fine particles. Size particles affects both their lifetime in the atmosphere and their physical and chemical properties. Because of this greater total surface area and their porosity the pesticides emitted as gas tend to be adsorbed mainly on them. Another factor that needs to be considered to explain pesticide size distribution is the residence time of particles in the atmosphere, that range from few days to few weeks. Particles are eventually removed from the atmosphere by dry and wet deposition. These processes are less efficient for particles in the 0.05e2 mm and 0.1e1 mm size range for dry and wet deposition, respectively (Seinfeld and Pandis, 2006). Diuron, diphenylamine and terbuthylazine-desethyl-2-OH were found in higher concentrations in the coarse fraction (2.5e10 and >10 mm). Wind erosion could introduce coarse particles (with pesticides adsorbed to them) in the troposphere. It is important to mention, that these pesticides are herbicides applied directly to the soil and in post-harvest storage. Other contribution to the coarse fraction is shifting of pesticides from fine to coarse particles. All of the detected pesticides are applied locally for the treatment of different crops in the area such as citrus fruit and fruit trees.
Following with the distribution of CUPs in ultrafine, fine and coarse fractions, Coscoll a et al. (2013a) also studied the particle size distribution of others CUPs in Centre region (France). Ambient air samples were also collected using a cascade impactor which distributes particles into four size fractions. Most pesticides were also accumulated in the fine (0.1e1 mm) particle size fraction such as cyprodinil, pendimethalin, fenpropidin, fenpropimorph and spiroxamine. Other pesticides such as acetochlor and metolachlor presented a bimodal distribution with maximum concentrations in the ultrafine (0.03e0.1 mm)-coarse (1e10 mm) and in the ultrafinefine size ranges, respectively. No pesticides were detected in the size fraction >10 mm. To the best of our knowledge, no other studies related with the particle size distribution of CUPs have been published. However, previous works have studied the size distribution of legacy or persistent pesticides in the ambient air. Chrysikou et al. (2009) collected size-segregated samples of urban particulate matter (<0.95, 0.95e1.5, 1.5e3.0, 3.0e7.5, >7.5 mm) in Thessaloniki (Greece), in order to study the size distribution of organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and aliphatic hydrocarbons. Unimodal normalized distributions, predominant at 0.95e1.5 mm size range, were also found for most organic compounds.
4. Conclusions Particle size distribution of currently used pesticides was investigated in a rural area of Spain. Most of the pesticides such as carbendazim, tebuconazole, chlorpyrifos-e and chlorpyrifos-m were accumulated in the ultrafine-fine (<1 mm) and coarse (2.5e10 mm) particle size fractions. However, diuron, diphenylamine and terbuthylazine-desethyl-2-OH also show a bimodal distribution but in the coarse size fraction (2.5e10 and >10 mm). Others like omethoate, dimethoate and malathion presented an unimodal distribution only in the ultrafine-fine size fraction (<1 mm). To the best of our knowledge, this is the first study about the size distribution of CUPs applied to Mediterranean crops.
Fig. 2. Particle size distribution of pesticides collected in Alzira site during all sampling period (2012e2013), plotted as normalized histogram approach (dC/dlogDp) versus Dp (Dp ¼ aerodynamic diameter, mm) (N ¼ 16).
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Acknowledgements Authors acknowledge to Arancha Rochina and Esther Escobedo for their help in sample preparation and analytical determination. They also thanks to Eva Villoldo for the sampling collection. n CEAM is partly supported by Generalitat Valenciana. Fundacio Appendix A. Supplementary data Supplementary data related to this article can be found at http:// dx.doi.org/10.1016/j.atmosenv.2014.06.022. References Allen, J.O., Dookeran, N.M., Smith, K.A., Sarofim, A.F., Taghizadeh, K., Lafleur, A., 1996. Measurement of polycyclic aromatic hydrocarbons associated with size segregated atmospheric aerosols in Massachusetts. Environ. Sci. Technol. 30, 1023e1031. Avino, P., Cinelli, G., Notardonato, I., Russo, M.V., 2011. Investigation on the behaviour of pesticides in the atmosphere. Aerosol Air Qual. Res. 11, 783e790. Bedos, C., Cellier, P., Calvet, R., Barriuso, E., Gabrielle, B., 2002a. Mass transfer of pesticides into the atmosphere by volatilization from soils and plants: overview. Agronomie 22, 21e33. Bedos, C., Rousseau-Djabri, M.F., Flura, D., Masson, S., Barriuso, E., Cellier, P., 2002b. Rate of pesticide volatilization from soil: an experimental approach. Atmos. Environ. 36, 5917e5925. Bi, X., Sheng, G., Peng, P., Chen, Y., Fu, J., 2005. Size distribution of n-alkanes and polycyclic aromatic hydrocarbons (PAHs) in urban and rural atmospheres of Guangzhou, China. Atmos. Environ. 39 (3), 477e487. CEU (Council of the European Union), 1991. Council Directive of 15 July 1991, 91/ 414/ECC, Concerning the Placing of Plant Protection Products on the Market, OJ L 230, 19-8-1991, pp. 1e32. Chao, M.R., Hu, C.W., Ma, H.W., Chang-Chien, G.P., Lee, W.J., Chang, L.W., Wu, K.Y., 2003. Size distribution of particle-bound polychlorinated dibenzo-p-dioxins and dibenzofurans in the ambient air of a municipal incinerator. Atmos. Environ. 37, 4945e4954. Chrysikou, L.P., Gemenetzis, P.G., Samara, C.A., 2009. Wintertime size distribution of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in the urban environment: street- vs rooftoplevel measurements. Atmos. Environ. 43, 290e300. Chrysikou, L.P., Samara, C.A., 2009. Seasonal variation of the size distribution of urban particulate matter and associated organic pollutants in the ambient air. Atmos. Environ. 43, 4557e4569. , C., Yusa , V., Beser, M.I., Pastor, A., 2009. Multi-residue analysis of 30 Coscolla currently used pesticides in fine airborne particulate matter (PM 2.5) by microwave-assisted extraction and liquid chromatography-tandem mass spectrometry. J. Chromatogr. A 1216, 8817e8827. , C., Colin, P., Yahyaoui, A., Petrique, O., Yusa , V., Mellouki, A., Pastor, A., 2010. Coscolla Occurrence of currently used pesticides in ambient air of Centre region (France). Atmos. Environ. 44, 3915e3925. , C., Castillo, M., Pastor, A., Yus Coscolla a, V., 2011. Determination of 40 currently used pesticides in airborne particulate matter (PM 10) by microwave-assisted
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extraction and gas chromatography coupled to triple quadrupole mass spectrometry. Anal. Chim. Acta 693, 72e81. Coscoll a, C., Yahyaoui, A., Colin, P., Robin, C., Martinon, L., Val, S., Baeza-Squiban, A., , V., 2013a. Particle size distributions of currently used pesMellouki, A., Yusa ticides in a rural atmosphere of France. Atmos. Environ. 81, 32e38. Coscoll a, C., Hart, E., Pastor, A., Yus a, V., 2013b. LC-MS characterization of contemporary pesticides in PM10 of Valencia Region, Spain. Atmos. Environ. 77, 394e403. Duan, J., Xi, B., Tan, J., Sheng, G., Fu, J., 2007. Seasonal variation on size distribution and concentration of PAHs in Guangzhou city, China. Chemosphere 67, 614e622. Finizio, A., Mackay, D., Bidleman, T., Harner, T., 1997. Octanol-air partition coefficient as a predictor of partitioning of semi-volatile organic chemicals to aerosols. Atmos. Environ. 31 (15), 2289e2296. Harner, T., Bidleman, T.F., 1998. Octanol-air partition coefficient for describing particle/gas partitioning of aromatic compounds in urban air. Environ. Sci. Technol. 32, 1494e1502. , C., Pastor, A., Yus Hart, E., Coscolla a, V., 2012. GCeMS characterization of contemporary pesticides in PM10 of Valencia Region, Spain. Atmos. Environ. 62, 118e129. Health Effects Institute, 2002. Understanding the health effects of components of the particulate matter mix; progress and next steps. HEI Perspect., 3e5. Hilz, E., Vermeer, A.W.P., 2013. Spray drift review: the extent to which a formulation can contribute to spray drift reduction. Crop Prot. 44, 75e83. ~ oz, A., Borra s, E., Martin-Reviejo, M., Wirtz, K., 2007. Le Person, A., Mellouki, A., Mun Trifluralin: photolysis under sunlight conditions and reaction with OH.radicals. Chemosphere 67, 376e383. ~ oz, A., Vera, T., Sidebottom, H., Mellouki, A., Borr denas, M., Mun as, E., Ro zquez, M., 2011a. Studies on the atmospheric degradation of Clemente, E., Va chlorpyrifos-methyl. Environ. Sci. Technol. 45, 1880e1886. ~ oz, A., Le Person, A., Le Calve , A., Mellouki, A., Borra s, E., Dae €le, V., Vera, T., Mun 2011b. Studies on atmospheric degradation of diazinon in the EUPHORE simulation chamber. Chemosphere 85, 724e730. Oh, J.E., Chang, Y.S., Kim, E.J., Lee, D.W., 2002. Distribution of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in different sizes of airborne particles. Atmos. Environ. 36, 5109e5117. Seinfeld, J.H., Pandis, S.N., 2006. Atmospheric Chemistry and Physics “From Air Pollution to Climate Change”, second ed. Wiley-Interscience Publication. Sofuoglu, A., Cetin, E., Bozacioglu, S.S., Sener, G.D., Odabasi, M., 2004. Short-term variation in ambient concentrations and gas/particle partitioning of organochlorine pesticides in Izmir, Turkey. Atmos. Environ. 38, 4483e4493. Van de Berg, F., Kubiak, R., Benjey, W.G., Majewski, M.S., Yates, G.L., Reeves, J.H., Smelt, J.H., Van Der Liden, A.M., 1999. Emission of pesticides into the Air. Water Air Soil. Pollut. 115, 195e218. Venkataraman, C., Friedlander, S.K., 1994. Size distribution of polycyclic aromatic hydrocarbons and elemental carbon. 2. Ambient measurements and effects of atmospheric processes. Environ. Sci. Technol. 28, 563e572. Voutsas, E., Vavva, C., Magoulas, K., Tassios, D., 2005. Estimation of the volatilization of organic compounds from soil surfaces. Chemosphere 58, 751e758. Wu, S.P., Tao, S., Liu, W.X., 2006. Particle size distributions of polycyclic aromatic hydrocarbons in rural and urban atmosphere of Tianjin, China. Chemosphere 62, 357e367. Zereini, F., Alt, F., Messerschmidt, J., Wiseman, C., Feldman, I., von Bohlen, A., Muller, J., Liebl, K., Püttmann, W., 2005. Concentration and distribution of heavy metals in urban airborne particulate matter in Frankfurt am Main. Ger. Environ. Sci. Technol. 39, 2983e2989.
Contents lists available at ScienceDirect
Atmospheric Environment journal homepage: www.elsevier.com/locate/atmosenv
Particle size distributions of currently used pesticides in ambient air of an agricultural Mediterranean area a, d, *, Amalia Mun ~ oz b, d, Esther Borra s b, d, Teresa Vera b, d, Clara Coscolla a, c, d denas b, d, Vicent Yusa Milagros Ro a
Public Health Laboratory of Valencia-FISABIO, 21, Avenida Catalunya, 46020 Valencia, Spain neo (CEAM), 14, Charles Robert Darwin, P. Tec. Paterna, 46980 Valencia, Spain n Centro de Estudios Ambientales del Mediterra Fundacio ~ oz, Dr. Moliner 50, 46100 Burjassot, Spain Analytical Chemistry Department, University of Valencia, Edifici Jeroni Mun d Atmospheric Pesticide Research Group of Valencia, Spain b c
h i g h l i g h t s Particle size distribution of pesticides in Mediterranean agriculture was studied. Pesticides accumulated in the ultrafine-fine and coarse particle size fractions. The total concentrations in the particulate phase ranged from 3.5 to 383.1 pg m3.
a r t i c l e i n f o
a b s t r a c t
Article history: Received 11 February 2014 Received in revised form 5 June 2014 Accepted 10 June 2014 Available online 10 June 2014
This work presents first data on the particle size distribution of 16 pesticides currently used in Mediterranean agriculture in the atmosphere. Particulate matter air samples were collected using a cascade impactor distributed into four size fractions in a rural site of Valencia Region, during July to September in 2012 and from May to July in 2013. A total of 16 pesticides were detected, including six fungicides, seven insecticides and three herbicides. The total concentrations in the particulate phase (TSP: Total Suspended Particulate) ranged from 3.5 to 383.1 pg m3. Most of the pesticides (such as carbendazim, tebuconazole, chlorpyrifos-ethyl and chlorpyrifos-methyl) were accumulated in the ultrafine-fine (<1 mm) and coarse (2.5e10 mm) particle size fractions. Others like omethoate, dimethoate and malathion were presented only in the ultrafine-fine size fraction (<1 mm). Finally, diuron, diphenylamine and terbuthylazinedesethyl-2-OH also show a bimodal distribution but mainly in the coarse size fractions. © 2014 Elsevier Ltd. All rights reserved.
Keywords: Pesticide Size distribution Atmospheric concentrations
1. Introduction The particle size distribution affects the particulate matter's transport in air, the dry or wet deposition from the atmosphere onto natural surfaces and the deposition in the human lungs. So, information about the particle size distribution of organic compounds is vital in order to estimate their inputs into the ecosystems and the human health (Wu et al., 2006; Chrysikou et al., 2009) . Small particles penetrate in the respiratory system, and cause direct health impact (Chrysikou and Samara, 2009). Therefore, particle size distribution of organic pollutants such as n-alkanes, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polychlorinated
* Corresponding author. Public Health Laboratory of Valencia-FISABIO, 21, Avenida Catalunya, 46020 Valencia, Spain. E-mail address: [email protected] (C. Coscoll a). http://dx.doi.org/10.1016/j.atmosenv.2014.06.022 1352-2310/© 2014 Elsevier Ltd. All rights reserved.
dibenzo-p-dioxins, dibenzofurans and metals has been repeatedly studied in several areas around the world (Bi et al., 2005; Allen et al., 1996; Duan et al., 2007; Chrysikou et al., 2009; Oh et al., 2002; Chao et al., 2003; Zereini et al., 2005). However, to our knowledge, only one study have been published related with par ticle size distribution of currently used pesticides (CUPs) (Coscolla et al., 2013a). Semivolatile organic compounds (SVOCs) can be bound to particles with different particle size distribution. Particles can be divided roughly into modes. The nucleation (or nuclei) mode comprises particles with diameters up to 0.01 mm. The Aitken mode spans the size range from about 0.01 mm to 0.1 mm diameter. These two modes account for the preponderance of particles by number; because of their small size, these particles rarely account for more than a few percent of the total mass of airborne particles. The accumulation mode, extending from 0.1 to 2.5 mm, usually accounts
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et al. / Atmospheric Environment 95 (2014) 29e35 C. Coscolla
for most of the aerosol surface area and a substantial part of the aerosol mass. The accumulation mode is so named because particle removal mechanisms are least efficient in this regime, causing particles to accumulate there. The coarse mode, from >2.5 mm in diameter, is formed by mechanical processes and usually consists of human-made and natural dust particles. Coarse particles have sufficiently large sedimentation velocities that they settle out of the atmosphere in a reasonable short time (Seinfeld and Pandis, 2006). Fig. 1 a shows the emission sources throughout CUPs can reach the atmosphere and the processes that permit their distribution in the different particle size fractions. There are three different emission sources during or after pesticide application in agricultural practices. Firstly, “spray drift” occurs during its application. A fraction of the dosage e 20e30% (Van de Berg et al., 1999) e applied to the target area could be deposited onto the adjacent non-target areas and another fraction can be lost in the atmosphere (Hilz and Vermeer, 2013). Secondly, volatilization is a post-application emission from soil and plants. It can happen some days or weeks after application (Bedos et al., 2002a). Thirdly, wind erosion of soil particles containing sorbed pesticides represent further significant pesticide input into the troposphere for several days or weeks after application (Voutsas et al., 2005). In addition, processes (see Fig. 1b) throughout pesticides are distributed in the three particle size fraction such as ultrafine, fine and coarse basically depend on the
following factors: the primary emission, the gas to particle distribution (G/P distribution) of the pesticide and the particle transformation by different pathways (Bedos et al., 2002b; Voutsas et al., 2005). Transformation in size occurs by different routes. Growth of particles can correspond to an increase of the mean particle size or shifting of parts of the distribution to larger sizes. Pesticides accumulated in ultrafine can shift to fine size fraction. Small pesticide particles and gaseous pesticides originate from emission sources (primary emissions) can be accumulated in ultrafine fraction. They can growth by coagulation or vapour condensation and then move to be associated in the fine particle size fraction (Venkataraman and Friedlander, 1994). Moreover, pesticides accumulated in the fine size fraction can shift to the coarse fraction. Freshly emitted pesticides can be adsorbed mainly to fine aerosol and they can become associated with coarse particles by volatilization from fine particles followed by condensation onto coarse particles (Bi et al., 2005; Duan et al., 2007). Research concerning the size distribution of particle-bound organochlorine pesticides (OCPs) in the atmosphere of Thessaloniki (Greece) has shown strong accumulation in the submicron size fraction. OCPs are known to be toxic to humans and many organisms, and are considered widespread environmental contaminants (Chrysikou and Samara, 2009). Moreover, currently used pesticides
Fig. 1. Sources and processes involved in the distribution of pesticides in the particle size fractions (G/P distribution ¼ gas to particle distribution).
et al. / Atmospheric Environment 95 (2014) 29e35 C. Coscolla
(CUPs) are the newly pesticides which are nowadays applied in the agricultural practices and are approved by EU regulations (CEU, 1991). In a recent previous study, we presented first data on the particle size distributions of current-used pesticides. This study was focused on pesticides applied to arable crops in an agricultural Continental area. In that study, most pesticides were accumulated in the fine particle size fraction (Coscoll a et al., 2013a). The main objective of this work is to study the size particle distribution of different currently used pesticides in the ambient air of an agricultural Mediterranean region. To our knowledge, this study represents the first investigation for particle size distribution of CUPs applied to Mediterranean agriculture. 2. Experimental 2.1. Pesticide selection Eighty-two pesticides and metabolites were studied which were all CUPs. CUPs approved by the EU regulations were applied mainly into citrus crops but also in other crops in the surrounded area during the sampling period. Pesticide selection was based mainly on pesticide amount applied in the region. Tables SD-1.1 and SD-1.2 show some characteristics of the studied pesticides. 2.2. Sampling and site characterization Sampling was undertaken at one sampling site located in Valencia Region, Spain. The station was placed in a rural area in the centre of the Valencia region, approximately 1 km from the city of Alzira (0 270 _2800 W, 39 090 _0000 N). Alzira has 42,543 inhabitants and is situated 43 km from Valencia city. It has in its vicinity many citrus groves such as orange trees. Samples were collected about 3 m above ground level. A Gravimetric Impactor was used for the measurement of atmospheric aerosols size distribution. DLPI Impactor (Dekati, Tampere, Finland) is a 4-stage cascade impactor and it measures gravimetric particle size distribution. Size fractions were as follows: <1 mm, 2.5e1 mm, 10e2.5 mm and >10 mm. Particles were collected on 25 and 47-mm-diameter glass fibre filters (GFFs) during one week with an average flow rate of 30 L min1. The total volume collected was around 300 m3 (see Table SD-2). A total of 16 samples were collected, randomly during weekdays. Samples were collected from July to September in 2012 (8 weeks) and from May to July in 2013 (8 weeks). These sampling weeks are the most relevant period for pesticide application. Prior to exposition, filters were baked for 24 h at 130 C to eliminate organics. To determine the weight of particulate matter (PM) accumulated during one-week exposition of filters, a Metter Toledo MX5 microbalance from (Bedford, MA, USA) was used. Filters were previously conditioned according to European standard sampling regulations (EN 12341:1998), at temperature 20 ± 1 C and at relative humidity 50 ± 5 C for at least 48 h, and then weighed. PM for each size fraction was measured weighting each filter after one week of exposure. TSP (Total Suspended Particulate) was calculated as the sum of the four size fractions. 2.3. Sample analysis The experimental work of this study was based on methods previously published. In short, pesticides were extracted from filters using ethyl acetate and microwave assisted extraction (MAE) and were subsequently detected using an LCeMS/MS system consisting of a high performance liquid chromatograph (HPLC) and TSQ , CA, USA). Electrospray Quantum Ultra mass spectrometer (San Jose ionization (ESI) and selected reaction monitoring mode (SRM) were
31
et al., 2009). The transitions and used for all analytes (Coscolla limits of quantification for these analytes can be found in Table SD3. In the case of GCeMS/MS amenable pesticides, the method includes extraction of PM10-bound pesticides by microwave-assisted extraction (MAE) followed by gel-permeation chromatography (GPC) clean-up and determination by GCeMS/MS. Chromatographic analyses were performed on a Trace GC Ultra and Triplus autosampler coupled to a triple quadrupole mass spectrometer , CA, USA). The from Thermo-Finningan (TSQ Quantum GC, San Jose mass spectrometer was operated in electron impact mode (EI). Selected reaction monitoring mode (SRM) was used for all analytes et al., 2011). Table SD-4 shows some selected GCeMS/MS (Coscolla parameters and the limits of quantification for each pesticide. 2.4. Quality control protocol Each set of samples was analysed using quality assurance protocols. In order to determine the possibility of background pollution, blank filters were routinely deployed in the field to determine any contamination during sample handling. No pesticides were detected (
Table 1 Concentration (mean ± SD)a of particle-bound pesticides during the sampling period (2012e2013). Pesticides
Carbendazim Terbuthylazine Metalaxyl Tebuconazole Omethoate Terbuthylazine desethyl-2-OH Dimethoate Diuron Diphenylamine Chlorpyrifos-e Chlorpyrifos-m Trifluralin Folpet Malathion Penconazole Diazinon
Total concentration Total concentration PM 10 concentration 2012 (pg m3) 2013 (pg m3) 2010 (pg m3) (N ¼ 8)
(N ¼ 8)
138 ± 7 39 ± 5 4 32 ± 8 e 383 ± 190
75 23 e e 6 129
e 53 ± 12 104 ± 13 24 ± 3 e e e e 3.54 e
4 82 e 141 35 27 39 10 16 22
± 11 ±3
±2 ± 18 ±1 ±4 ± ± ± ± ± ± ±
33 1 1 1 5 1 1
(N ¼ 232)b,c 59.7 118.1 39.1 10 141.2 48.9 45.1 e 6.1 14.5 7.3 e 45.6 13.8 e 20.8
PM Total Suspended Particulate ¼ 10e19 mm m3. N ¼ Number of total samples. PM: Particulate matter. a The mean concentration was calculated from samples with concentration above LOQ. b Hart et al., 2012. c Coscoll a et al., 2013a,b.
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particulate phase. Nine pesticides were found during the sampling period in 2012 (see Table 1). Fungicides (carbendazim, metalaxyl, tebuconazole, diphenylamine and penconazole) were presented in concentrations ranging from 3.54 to 138 pg m3. Insecticides (diphenylamine and chlorpyrifos-e) were detected with total concentrations of 104 pg m3 and 24 pg m3, respectively. Herbicides (diuron and terbuthylazine and its metabolites) presented concentrations from 39 to 383 pg m3. Except for diphenylamine, these CUPs were authorized for the treatment of different crops mainly citrus groves by the European Union. In the case of diphenylamine, its presence could be linked with an illegal use. Most of the detected pesticides presented a high volatility (>101 Pa). Other pesticides such as carbendazim, diuron and tebuconazole have medium volatility (103e105 Pa). They also have atmospheric life (DT50) of few hours (Tables SD-1.1 and 1.2). The levels of pesticides in the atmosphere depend not only on its volatility or its atmospheric half-life, but also on their usage and the et al., conditions of the applications in the studied area (Coscolla 2010). SVOCs can be distributed between the gas and particulate phases (G/P) in the atmosphere. This distribution has been described according to different models. The octanoleair partitioning coefficient (Koa) has been proposed (Finizio et al., 1997; Harner and Bidleman, 1998; Sofuoglu et al., 2004) as a good descriptor of the absorption of SOCs to aerosols, and consequently it seems a useful predictor for the G/P partitioning of some organic pollutants. Following this theoretical model, some detected pesticides such as carbendazim, diuron and tebuconazole (Koa >10) are expected to be found mainly in the particle phase in a percentage higher than 50%. The other detected pesticides should be present mainly in the gaseous phase; the model predicts the partition for these CUPs in the particle phase ranging from 1 to 49%. Consequently, the detection of pesticides in the particulate phase for these pesticides in our study could be linked with their high usage in the studied area, and to the fact that sampling coincides to the application period of pesticides. Fungicides (metalaxyl and penconazole) were applied extensively for the treatment of different crops during the sampling period in Alzira site. Metalaxyl was used for the treatment of citrus fruit (Phytophthora spp.), vineyards (Plasmopara vitícola) and different vegetables such as potatoes, cauliflower, lettuce and peppers (Mildiu, Bremia lactucae and Phytophthora capsici). Chlorpyrifos-e insecticide is a broad-spectrum pesticide used in Valencia Region to treat different pests in almost all crops, mainly citrus fruit. Terbuthylazine herbicide is used on citrus, olive trees and fruit treatments in the area. Table 1 also presents a total number of 13 compounds detected during the sampling period in 2013. Carbendazim, terbuthylazine and its metabolite, diuron, chlorpyrifos-e and penconazole were observed during two-year study. Only diuron (82 pg m3), penconazole (16 pg m3) and chlorpyrifos-e (141 pg m3) presented lower concentrations in 2013. Five insecticides (omethoate, dimethoate, chlorpyrifos-m, malathion and diazinon), one fungicide (folpet) and one herbicide (trifluralin) were detected only during year 2013. Insecticides were presented in concentrations ranging from 4 to 35 pg m3. The fungicide was detected with total concentration of 39 pg m3. The unique herbicide detected this year was found with 27 pg m3. Except for omethoate, trifluralin and diazinon, these CUPs were authorized for the treatment of different crops mainly citrus groves by the European Union. In the case of omethoate, it is important to note that it has been banned in the European Union since 2003. Its detection is not probably related with an illegal use, but due to the fact that omethoate is a transformation product from dimethoate (Avino et al., 2011). The atmospheric oxidation of dimethoate is
likely that leads to the formation of the corresponding oxon (omethoate) similarly to the reaction channel of degradation of ~ oz et al., 2011a). Trifluralin and diazinon chlorpyrifos methyl (Mun are currently banned in the European Union, and taking into account that the atmospheric lifetime in gas-phase of these compounds are 15 min and 4 h respectively (Le Person et al., 2007; ~ oz et al., 2011b) it is suggested a possible illegal use of these Mun pesticides. All pesticides detected only in year 2013 also presented a high volatility (>101 Pa), except for folpet (2.1 102 Pa), which have medium volatility. They also have atmospheric life (DT50) of few hours (Tables SD-1.1 and 1.2). Following the theoretical model proposed by Harner and Bidleman (1998), omethoate (Koa ¼ 11) is expected to be found mainly in the particle phase in a high percentage (91%). However, the other detected pesticides (dimethoate, chlorpyrifos-m, trifluralin, folpet, malathion and diazinon) should be present mainly in the gaseous phase. The model predicts the partition for these CUPs in the particle phase ranging from 1 to 13%. Consequently, the detection of pesticides in the particulate phase for these pesticides in our study could be linked with their high usage in the studied area, and to the fact that sampling coincides to the application period of pesticides. Dimethoate is applied extensively in citrus fruit and olives. This insecticide is used against the olive fly (Bactrocera oleae) and is also used on citrus fruit plagued with aphids (Aphis sp., Toxoptera aurantii) in Alzira site. Chlorpyrifos-m and malathion are used in citrus fruit, fruit and grape in the studied area. Trifluralin is a herbicide used on soil prior to emergence of the desired plant to control annual grasses and broad-leaved weeds. Folpet is applied to the treatment of fruits and grapes. Diazinon is an organophosphate insecticide that was applied in the studied region for pest treatment of citrus fruit (Planococcus citri, Ectomyelois ceratoniae, Cryptoblabes gnidiella and ants), stone, and nugget fruits (Quadraspidiotus perniciosus). Two previous studies in the same sampling site (Alzira station) et al., 2013b; Hart et al., 2012) detected during 2010 (Coscolla similar pesticides as the present study, but samples were collected from January to December 2010. PM10 samples were collected using a high volume sampler and the sampling flow was 30 m3 h1 for 24 h, giving a total volume of filtered air around 720 m3. No temporal variations in pesticide air concentrations were observed for some pesticides such as diazinon, folpet and malathion. However, some differences during this period 2010e2013 should be stressed. A slight decline in the levels has been observed in the present study for pesticides such as terbuthylazine, metalaxyl, dimethoate and omethoate. On the other hand, for tebuconazole, diphenylamine and chlorpyrifos-m a slight increase has been observed. 3.2. Size distribution concentration using cascade-impactor The aerodynamic diameter (a.d.) of aerosol particles span over four orders of magnitude, from a few nanometres to around 100 mm. From the point of view of health effects, the size categories are defined as: ultrafine particles, smaller than about 0.1 mm in a.d; fine particles, smaller than 1 mm a.d; and coarse particles larger than 1 mm a.d. (Health Effects Institute, 2002). Out of the 82 pesticides studied in the different particle size fractions, only sixteen pesticides were detected at least in one sample (see Table 2). The particle size distribution of some of these pesticides is presented in Fig. 2. Three types of distribution were found as follows: unimodal ultrafine-fine (UFeF), bimodal (UFeF/ coarse) and mainly bimodal coarse distribution. A usual approach for studying the distribution of pollutants in the different size fractions is to use normalized histograms representing dC/dlogDp vs. Dp, where dC is the concentration of
et al. / Atmospheric Environment 95 (2014) 29e35 C. Coscolla
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Table 2 Concentration (mean ± SD)a,b and frequency of detection of particle-bound pesticides in ultrafine, fine and coarse size ranges during the sampling period (2012e2013). Pesticides
Size fraction <1 mm (PM: 6e10 mm m3)
Carbendazim Terbuthylazine Tebuconazole Omethoate Dimethoate Diuron Diphenylamine Chlorpiryfos-e Chlorpiryfos-m Penconazole Trifluralin Folpet Malathion Diazinon Terbuthylazine desethyl-2-OH Metalaxyl
1e2.5 mm (PM: 2e5 mm m3)
2.5e10 mm (PM: 2e3 mm m3)
>10 mm (PM: up 1 mm m3)
Concentration (pg m3)
Frequency of detection (%)
Concentration (pg m3)
Frequency of detection (%)
Concentration (pg m3)
Frequency of detection (%)
Concentration (pg m3)
Frequency of detection (%)
28 ± 18 13 ± 10 16 ± 11 5±2 4±1 17 ± 12 38 ± 26 50 ± 49 9±1 6±3 0 10 ± 1 10 ± 5 11 221 ± 220 4
94 75 25 19 12 19 12 81 25 12 e 37 25 6 44 6
13 ± 8 5±4 0 0 0 19 ± 17 13 ± 12 15 ± 13 9±1 0 8 10 0 11 55 ± 30 e
56 50 6 e e 19 12 69 12 e 6 6 e 6 12 e
15 ± 10 8±6 9±6 0 0 25 ± 2 35 16 ± 12 8±1 0 9±1 9 0 0 e e
50 56 12 e e 31 6 56 12 e 12 6 e e e e
9±5 7±5 0 0 0 18 ± 9 17 ± 16 12 ± 11 9 8 10 10 0 0 52 ± 50 e
25 44 e e e 31 12 62 6 12 6 6 e e 12 e
PM: Particulate matter. PMTotal Suspended Particulate ¼ 10e19 mm m3. a Number of total samples: 16. b The mean concentration and frequency of detection was calculated from samples with concentration above LOQ.
pesticides in each size fraction; and Dp is the aerodynamic diameter (Chrysikou et al., 2009). Omethoate, dimethoate and malathion presented an unimodal distribution in the ultrafine-fine size fraction (<1 mm). On the other hand, carbendazim, tebuconazole, chlorpyrifos-e and chlorpyrifosm presented a basically bimodal pesticide size distribution with peaks on the ultrafine-fine (<1 mm) and coarse (2.5e10 mm) fractions. However, diuron, diphenylamine and terbuthylazinedesethyl-2-OH also shows a bimodal distribution but in the coarse size fraction (2.5e10 and >10 mm) (see Fig. 2). The presence of some pesticides in the ultrafine-fine fraction (carbendazim, tebuconazole, chlorpyrifos-e, chlorpyrifos-m, omethoate, dimethoate, malathion) could be mainly linked to freshly emitted pesticides as primary ultrafine aerosols, and vapour condensation in this fraction. Mechanisms which contribute to pesticides distributed in particle fine size fraction, as is the case of these pesticides, are primary emissions as fine aerosols, adsorption of gas emitted pesticides to fine particles present in the atmosphere (higher surface area) and coagulation of ultrafine to fine particles. Size particles affects both their lifetime in the atmosphere and their physical and chemical properties. Because of this greater total surface area and their porosity the pesticides emitted as gas tend to be adsorbed mainly on them. Another factor that needs to be considered to explain pesticide size distribution is the residence time of particles in the atmosphere, that range from few days to few weeks. Particles are eventually removed from the atmosphere by dry and wet deposition. These processes are less efficient for particles in the 0.05e2 mm and 0.1e1 mm size range for dry and wet deposition, respectively (Seinfeld and Pandis, 2006). Diuron, diphenylamine and terbuthylazine-desethyl-2-OH were found in higher concentrations in the coarse fraction (2.5e10 and >10 mm). Wind erosion could introduce coarse particles (with pesticides adsorbed to them) in the troposphere. It is important to mention, that these pesticides are herbicides applied directly to the soil and in post-harvest storage. Other contribution to the coarse fraction is shifting of pesticides from fine to coarse particles. All of the detected pesticides are applied locally for the treatment of different crops in the area such as citrus fruit and fruit trees.
Following with the distribution of CUPs in ultrafine, fine and coarse fractions, Coscoll a et al. (2013a) also studied the particle size distribution of others CUPs in Centre region (France). Ambient air samples were also collected using a cascade impactor which distributes particles into four size fractions. Most pesticides were also accumulated in the fine (0.1e1 mm) particle size fraction such as cyprodinil, pendimethalin, fenpropidin, fenpropimorph and spiroxamine. Other pesticides such as acetochlor and metolachlor presented a bimodal distribution with maximum concentrations in the ultrafine (0.03e0.1 mm)-coarse (1e10 mm) and in the ultrafinefine size ranges, respectively. No pesticides were detected in the size fraction >10 mm. To the best of our knowledge, no other studies related with the particle size distribution of CUPs have been published. However, previous works have studied the size distribution of legacy or persistent pesticides in the ambient air. Chrysikou et al. (2009) collected size-segregated samples of urban particulate matter (<0.95, 0.95e1.5, 1.5e3.0, 3.0e7.5, >7.5 mm) in Thessaloniki (Greece), in order to study the size distribution of organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and aliphatic hydrocarbons. Unimodal normalized distributions, predominant at 0.95e1.5 mm size range, were also found for most organic compounds.
4. Conclusions Particle size distribution of currently used pesticides was investigated in a rural area of Spain. Most of the pesticides such as carbendazim, tebuconazole, chlorpyrifos-e and chlorpyrifos-m were accumulated in the ultrafine-fine (<1 mm) and coarse (2.5e10 mm) particle size fractions. However, diuron, diphenylamine and terbuthylazine-desethyl-2-OH also show a bimodal distribution but in the coarse size fraction (2.5e10 and >10 mm). Others like omethoate, dimethoate and malathion presented an unimodal distribution only in the ultrafine-fine size fraction (<1 mm). To the best of our knowledge, this is the first study about the size distribution of CUPs applied to Mediterranean crops.
Fig. 2. Particle size distribution of pesticides collected in Alzira site during all sampling period (2012e2013), plotted as normalized histogram approach (dC/dlogDp) versus Dp (Dp ¼ aerodynamic diameter, mm) (N ¼ 16).
et al. / Atmospheric Environment 95 (2014) 29e35 C. Coscolla
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