Science of the Total Environment 586 (2017) 107–114
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Persistent Organic Pollutants (POPs) in the atmosphere of three Chilean cities using passive air samplers Karla Pozo a,b,c,d,⁎, Germán Oyola e, Victor H. Estellano d, Tom Harner f, Anny Rudolph a, Petra Prybilova c, Petr Kukucka c, Ondrej Audi c, Jana Klánová c, America Metzdorff a,d, Silvano Focardi d a
Universidad Católica de la Santísima Concepción, Facultad de Ciencias, Concepción, Chile Universidad Católica de la Santísima Concepción, Centro de Investigación en Biodiversidad y Ambientes Sustentables (CIBAS), Concepción, Chile Masaryk University, Faculty of Science, Research Center for Toxic Compounds in the Environment (RECETOX), Brno, Czech Republic d Universitá degli Studi di Siena, Dipartimento Scienze ﬁsiche, della Terra e dell'ambiente, Siena, Italy e Ministery of the Environment (MMA), Air Quality Division and Climate change, Santiago, Chile f Air Quality Processes Research Section, Environment and Climate Change Canada, Toronto, ON, Canada b c
H I G H L I G H T S
G R A P H I C A L
A B S T R A C T
• Passive air samplers were used to assess POPs in three major cities of Chile • OCPs, PCBs, and PBDEs (ﬂame retardants) were detected at all cities • POPs levels were similar in the 3 cities but higher than background/rural sites • PBDEs were similar compared to other cities around the world using PUF-PAS methods • The new data support the reporting for the GRULAC region under the SC on POPs.
a r t i c l e
i n f o
Article history: Received 22 June 2016 Received in revised form 8 November 2016 Accepted 9 November 2016 Available online 4 January 2017 Editor: Adrian Covaci Keywords: Urban atmosphere POPs PBDEs PAS-PUF
a b s t r a c t In this study passive air samplers containing polyurethane foam (PUF) disks were deployed in three cities across Chile; Santiago (STG) (n = 5, sampling sites), Concepciόn (CON) (n = 6) and Temuco (TEM) (n = 6) from 2008 to 2009. Polychlorinated biphenyls (PCBs) (7 indicator congeners), chlorinated pesticides hexachlorocyclohexanes (HCHs), dichlorodiphenyl trichloroethanes (DDTs) and ﬂame retardants such as polybrominated diphenyl ethers (PBDEs) were determined by gas chromatography coupled mass spectrometry (GC/MS). A sampling rate (R) typical of urban sites (4 m3/day) was used to estimate the atmospheric concentrations of individual compounds. PCB concentrations in the air (pg/m3) ranged from ~1–10 (TEM), ~1–40 (STG) and 4–30 (CON). Higher molecular weight PCBs (PCB-153, −180) were detected at industrial sites (in Concepción). The HCHs showed a prevalence of γ-HCH across all sites, indicative of inputs from the use of lindane but a limited use of technical HCHs in Chile. DDTs were detected with a prevalence of p,p′-DDE accounting for ~50% of the total DDTs. PBDE concentrations in air (pg/m3) ranged from 1 to 55 (STG), 0.5 to 20 (CON) and from 0.4 to 10 (TEM), and were generally similar to those reported for many other urban areas globally. The pattern of PBDEs was different
⁎ Corresponding author at: Universidad Católica de la Santísima Concepción, Facultad de Ciencias, Concepción, Chile. E-mail addresses: [email protected]
, [email protected]
http://dx.doi.org/10.1016/j.scitotenv.2016.11.054 0048-9697/© 2016 Elsevier B.V. All rights reserved.
K. Pozo et al. / Science of the Total Environment 586 (2017) 107–114
among the three cities; however, PBDE-209 was dominant at most of the sites. These results represent one of the few assessments of air concentrations of POPs across different urban areas within the same country. These data will support Chilean commitments as a signatory to the Stockholm Convention on POPs and for reporting as a member country of the Group of Latin America and Caribbean Countries (GRULAC) region. © 2016 Elsevier B.V. All rights reserved.
1. Introduction Persistent Organic Pollutants (POPs) such as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and brominated ﬂame retardants (polybrominated diphenyl ethers (PBDEs)) are environmental contaminants of international concern because it has been demonstrated that they cause adverse effects to humans and the environment. These compounds have been restricted under the Stockholm Convention (SC) on POPs (Stockholm Convention, 2015), to which all South American countries are parties. Chile signed the SC in May 2003 and ratiﬁed it in 2005, and accordingly it is also a part of the Group of Latin America and Caribbean Countries (GRULAC) region. Urban areas in Chile are highly populated zones and usually host industrial settlements where chemicals are emitted in the atmosphere, transported, and subsequently, partially deposited on the surface. Consequently, human exposure represents a key risk associated with anthropogenic activities and urban/industrial development. In Chile, the air monitoring programs, under the Ministry of the Environment measure compounds such as CO, Pb, NO2, PM10, PM2.5, O3, SO2. To date however, there has been no comprehensive monitoring or research program for POPs and other priority air contaminants to address the mechanisms of transport and partitioning, and their ultimate fate (including human exposure pathways). This lack of information is at least partially explained by the high costs of air monitoring programs, which rely on active air sampling and incur large associated infrastructure and equipment costs. During the last 10 years passive air sampling has been developed as a cost-effective approach to characterize the atmospheric distribution of persistent POPs on a local, regional and global scale (Pozo et al., 2009; Klánová et al., 2009; Bogdal et al., 2013; Lee et al., 2016). Importantly, Chile has not yet established legally enforceable environmental standards for atmospheric pollutants. PCBs are a class of synthetic organic chemicals. Since the 1930s PCBs were heavily used for a variety of industrial processes principally because of their chemical stability. PCBs are considered immuno-toxic and have been proven to adversely impact reproduction processes. In Chile, PCBs were used intensively over the past 50 years; their main commercial sources were principally in electrical equipment as dielectric oils (e.g. in transformers). Chile carried out a national inventory of PCBs in 2004 and determined that the total volume present in the country reached 569,547 L of dielectric oil, of which 57% was in use. Additionally, the PCBs inventory for other uses determined that in Chile from 2002 to 2008, nearly 38,820 metric tons of products were imported and suspected of containing PCBs (Pozo et al., 2012, 2013). In 2009, new PCB data was incorporated in the Chilean PCB inventory mainly from the transportation and in particular for the rail transportation sectors. Other relevant information arising from the last PCB inventory was the amount of PCB removed showing 2007 as the year with the highest amount of PCB eliminated, attributed mainly to CODELCO (copper mining company) elimination strategies (Diagnóstico regional, 2013). Organochlorine pesticides have been used in Chile since the 1940s, mainly in agriculture. Of primary note, Hexachlorocyclohexane (HCH) was used in Chile as a commercial insecticide in two formulations; technical HCH and lindane, consisting of N95% γ-HCH isomer. Lindane was banned for agricultural use in Chile in 1998 but was still used until 2007 in public health and pharmaceutical preparations for the treatment of pediculosis and scabies/mange in humans and animals (PAN, 2008).
DDT, another compound investigated, has been widely used in South America since the 1940s, primarily to control insects that are vectors for diseases, such as malaria, dengue fever, and typhus. DDT continues to be the most produced and used POPs listed under the Stockholm Convention (Stockholm Convention, 2015) with exemptions for use in public health for disease vector control. Although Chile has not been affected by tropical diseases, DDT was used in agriculture until 1980s when the Servicio Agricola y Ganadero (SAG) of Chile (English deﬁnition: Chilean Agricultural Service) prohibited its importation, fabrication, sales, distribution and use. Flame retardants are a group of chemicals intended to slow the rate of ignition and retard the propagation of combustion in a wide variety of commercial and industrial products. The polybrominated diphenyl ethers (PBDEs) are found in a variety of consumer products, including TVs, toasters, mattresses and drapes. In recent years, the PBDEs have generated international concern over their widespread distribution in the environment, their potential to bioaccumulate in humans and wildlife, and suspected adverse human health effects (Stockholm Convention, 2015). Commercial production of PBDEs began in Germany in the 1970s (Besis and Samara, 2012). PBDEs are not manufactured in Chile, but Chile has imported commercial mixtures which were used in various intermediate and ﬁnished products; such as appliances, furniture inter alia. The main commercial mixtures used worldwide are the penta-, octa- and deca-PBDE. PBDEs have high octanol-water partition coefﬁcient (Kow) values; and therefore, they have been shown to accumulate in fatty tissue and bio-magnify with tropic level throughout the food chain (Ikonomou et al., 2002). Due to their toxicity and persistence, industrial production is restricted under the Stockholm Convention (Stockholm Convention, 2015). In Chile, previous studies have documented atmospheric contamination by POPs using different sampling techniques; conventional procedures rely principally on active air sampling (Cereceda-Balic et al., 2012; Díaz-Robles et al., 2014). In the last decade passive air samplers have contributed to research on POPs resulting in spatial monitoring studies and some cases long term networks (Jaward et al., 2004; Klánová and Harner, 2013; Pozo et al., 2009; Bogdal et al., 2013). In Chile, several studies have used PUF disk passive air sampling (PAS) to measure POPs (Pozo et al., 2004; Pozo et al., 2012; Pozo et al., 2015); however, there is still no comprehensive assessment of POPs in Chile to date which includes information on atmospheric transport, fate, ecosystem and human exposure and effects. The main objectives of this study are i) to assess the spatial distribution and seasonal variations of POPs in the Chilean atmosphere, with an emphasis on urban areas; ii) to provide new information that aids in risk management and Chilean and international regulatory reporting; and iii) to demonstrate the effectiveness of PUF disk samplers as monitoring and research tools for the determination of airborne concentrations of POPs and other emerging air contaminants.
2. Material and methods 2.1. Study area Polyurethane foam (PUF) disks were deployed in three cities in Chile across a range of sampling sites with different geographical and climatic conditions, and characterized by different predominate anthropogenic activities (Urban (UR), Rural (RU) and Industrial (IN) sites) from 2008
K. Pozo et al. / Science of the Total Environment 586 (2017) 107–114
to 2009 – see Fig. S1. The cities investigated in this study represent the largest cities in Chile: Santiago (STG, largest city of Chile, 7,314,176 inhabitants as reported by INE: Instituto National de Estadisticas; English translation: National Institute for Statistics) (n = 5, sampling sites; one Industrial site (Quilicura = STG1) and three urban sites (UR) (La Reina (CENMA) = STG2, San Ramon = STG3, Maipu = STG4 and one rural (RU) site (El Monte = STG5), Concepciόn (CON, second largest city in Chile) (n = 6 and included RU site (Penco = CON1), one urban site (Concepción downtown = CON2), four industrial sites (Coronel = CON3, Masisa = CON4, Indura = CON5, and Libertad = CON6), Temuco (TEM, the ﬁfth largest city) (n = 6 and considered two RU sites (Diego Portales = TEM1, Cerro Ñielol = TEM2) and four UR sites (Padre Las Casas = TEM3, Temuco down town = TEM4, Museo Ferroviario = TEM5, and Las Encinas = TEM6). Details for each city and sampling site are given in (Tables S1–S6). Sampling periods corresponded to Period 1: April–August (2008), Period 2: August–December (2008), Period 3: January–April (2009), Period 4: April–August (2009) (Tables S2, S4, S6). Sampling was carried out simultaneously at all sites throughout the study.
2.2. Sampling and sample preparation PUF disks were prepared as described in literature previously see: Pozo et al., 2009, Pozo et al., 2012. During exposure, PUF disks (14 cm diameter; 1.35 cm thick; surface area, 365 cm2; mass, 4.40 g; volume, 207 cm3; density, 0.0213 g/cm3; PacWill Environmental, Stoney Creek, ON) were housed inside a stainless steel chamber, deployed at their respective sites and exposed to the atmosphere for the entire period of measurement. The chamber consisted of two stainless steel domes with external diameters of 30 cm and 20 cm. Prior to extraction, PUF disks were spiked with a recovery standard consisting of 13C PCB-105, d8 DDT and d10 Phenanthrene (99%, Cambridge Isotope Laboratory) and extracted by Soxhlet for 24 h using petroleum ether. Liquid extracts were concentrated by rotary evaporation and blown down to 1 mL under nitrogen gas. Further details pertaining to the sampling and extraction procedure are reported elsewhere (Pozo et al., 2009; Pozo et al., 2012). The concentrated extract was split to 2 aliquots, 1/10 for PAHs analysis, and 9/10 for chlorinated (PCBs, OCPs) and brominated compound (PBDEs) analysis. Clean-up of the PCBs, OCPs and PBDE aliquot was performed on a modiﬁed silica column, 25 mm i.d. (3 g silica + 20 g 44% H2SO4 silica + 10 g 22% H2SO4 silica + 6 g silica + 10 g Na2SO4). The column was prewashed with 80 mL n-hexane and then was loaded with the respective concentrated extract and eluted with 150 mL n-hexane. The solvent volume was reduced in a TurboVap II concentrator unit and transferred into GC conical vials prior to the addition of analytical recovery standards.
2.4. Quality assurance/quality control (QA/QC) Method recoveries for target compounds were previously assessed for these analyses and were shown to be for the most part N 70%. Sample-speciﬁc surrogate recoveries for 13C PCB-105, d8 DDT and d10 Phenanthrene were used as they covered a wide range of volatilities with average percent recoveries of 80 ± 10, 75 ± 10, and 85 ± 5, respectively. Blank levels were assessed for 4 ﬁeld blanks and 4 laboratory blanks (solvent blanks). Field blanks were below detection concentrations for all screened compounds; accordingly no blank corrections were required. Method detection limits (MDL) in air samples were deﬁned as the average blank (n = 8) plus three standard deviations (SD). The instrumental detection limits were determined by assessing the injection amount that corresponds to a signal-to-noise value of 3:1. When target compounds were not detected in blanks, 1/2 of the instrumental detection limit (IDL) was substituted for the MDL (Table 1). 2.5. Statistical analysis Statistical analysis, including box and whisker plots (Fig. 3) and oneway Analysis of Variance (ANOVA) (SM, Table S8), were performed using R Studio (with R version 3.2.4, www.rstudio.com), and by using the library ggplot2 for the box and whisker plots. The performance of the one-way ANOVA was done using the function of R aov (formula, data = NULL) (https://stat.ethz.ch/R-manual/R-devel/library/stats/ html/aov.html). For the ANOVA analysis, the total composition of PCBs, HCHs and DDTs as related to the seasonal variation were assessed. 2.6. Deriving concentrations in air The method for estimating the concentration of chemicals in the air using PUF disk passive air sampling (PUF-PAS) has been reported previously e.g. Pozo et al., 2004; Gouin et al., 2005; Harner et al., 2013, Estellano et al., 2012; Bohlin et al., 2014. Brieﬂy, the concentration in the air of each target chemical was derived using the amount accumulated on the PUF disk (ng/sampler) during the entire deployment period, divided by the effective air sample volume (Vair, m3), which was estimated for each chemical and sample using the template provided by the GAPS Network (Harner, 2014). This template considers the full uptake proﬁle as described by Shoeib and Harner (2002), and comprises a linear and plateau phase. The plateau phase is relevant for the more volatile compounds such as α-HCH that may come to equilibrium with the PUF disk during the deployment period resulting in reduced Vair values as compared to less volatile compounds. We used the recommended default value for the sampling rate, R, of 4 m3/d, which is based on previous calibration studies of the PUF-PAS devices (Gouin et al., 2005; Pozo et al., 2009; He and Balasubramanian, 2010; Harner et al., 2014). Additional details about the calibration of PUF-PAS are presented elsewhere (e.g., Gouin et al., 2005; Pozo et al., 2004, 2006, 2009; Klánová et al., 2008; Harner et al., 2013, 2014; Bohlin et al., 2014).
2.3. Chemical analysis 3. Results and discussion The ﬁnal extracts were analyzed for PCBs (7 indicator congeners: PCB-28, -52, -105, -110, -118, -153, -180), Organochlorine pesticides (OCPs), Hexachlorocyclohexanes (HCH) (α-, b-, γ-, d-, e-), DDTs (p,p′DDE, o,p′-DDE, p,p′-DDD, o,p′-DDD, p,p′-DDT, o,p′-DDT) and 10 PBDE congeners (BDE-28, -47, -66, -99, -100, -85, -154, -153, -183, -209). PCB/OCPs were quantiﬁed using a GC–MS instrument (HP 6890 – HP 5975) with a J&W Scientiﬁc fused silica column DB-5MS (5% Ph) in electron ionization mode for OCPs and PCBs. Details of GC–MS conditions are reported in Pribylova et al., 2012. The PBDE analyses were performed by GC-High Resolution Mass Spectrometry (GC-HRMS) on a 7890A GC instrument (Agilent, USA) equipped with a RTX-1614 column (15 m × 0.25 mm × 0.10 μm) (Restek, USA) coupled to an AutoSpec Premier HRMS (Waters, Micromass, UK) (Pozo et al., 2015).
Concentrations of POPs in air during the four periods of sampling in 2008 to 2009 are presented in Table 1 and Figs. 1–3. A series of box and whisker plots are used to illustrate seasonal variations of targeted chemicals (Fig. 3). The results for each group of chemicals are presented and discussed below. 3.1. PCBs In general, PCB concentrations in air (pg/m3) were in the range of ~ 1–36 (~ 10 ± 9) (Table 1): ∑7PCBs (pg/m3) ranged from ~ 1–40 (13 ± 10) (STG), from 4 to 30 (12 ± 8) (CON) and from ~ 1–10 (3 ± 4) (TEM) (Tables S8–S13, Fig. S2).
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Table 1 Arithmetic mean, geometric mean ± standard deviation of POPs in three cities of Chile, during four sampling periods. ∑HCH
STG CON TEM
AM, GM ± SD 7.1, 6.6 ± 3.4 5.2, 3.5 ± 5.1 5.7, 3.7 ± 5.1
AM, GM ± SD 6.6, 6.2 ± 2.8 9.4, 3.5 ± 15.1 8.2, 5.0 ± 7.9
AM, GM ± SD 9.8, 7.9 ± 8.1 14.4, 12.8 ± 7.7 3.6, 2.4 ± 3.0
AM, GM ± SD 5.0, 2.9 ± 6.1 0.7, 0.6 ± 0.4 0.9, 0.7 ± 0.4
AM, GM ± SD 6.1, 4.0 ± 5.5 2.2, 1.1 ± 2.0 2.4, 0.3 ± 4.4
Period 2 STG CON TEM
4.0, 3.4 ± 2.2 8.1, 5.2 ± 7.9 4.0, 2.3 ± 5.3
3.7, 3.7 ± 0.6 10.4, 4.6 ± 16.5 4.6, 2.5 ± 4.4
6.1, 4.7 ± 4.2 16.2, 12.9 ± 12.2 4.2, 2.0 ± 5.1
1.3, 1.2 ± 0.7 4.5, 3.3 ± 4.7 1.6, 0.7 ± 2.6
11.1, 3.1 ± 12.6 1.5, 1.1 ± 1.1 6.8, 0.6 ± 13.9
Period 3 STG CON
9.4, 8.4 ± 5.8 7.4, 6.9 ± 2.6
6.2, 5.2 ± 5.0 6.1, 5.4 ± 3.0
16.1, 12.6 ± 13.8 9.4, 8.5 ± 4.6
1.7, 1.4 ± 1.2 0.6, 0.6 ± 0.2
19.3, 7.6 ± 24.0 1.3, 1.0 ± 0.8
Period 4 STG CON Rangea AM,GM
9.8, 8.6 ± 6.1 5.7, 4.0 ± 4.5 0.8–22 6.7, 4.7 ± 5.2
6.4, 5.5 ± 4.2 6.9, 3.4 ± 9.4 0.3–44 7.1, 4.2 ± 8.7
16.9, 14.1 ± 11.1 11.9, 9.8 ± 7.4 0.4–36 11, 7.4 ± 9
1.4, 1.4 ± 0.5 1.5, 1.4 ± 0.5 0.2–14 1.9, 1.2 ± 2.6
4.5, 3.2 ± 3.7 6.0, 2.9 ± 7.7 0.02–53 5.6, 1.6 ± 10.1
Range of four periods (maximum-minimum); arithmetic mean and geometric mean ± standard deviation of four periods.
The highest PCB levels were detected at Quilicura (STG1) in STG, Libertad (CON6) in CON and Temuco center (TEM4) in TEM. When comparing our results with previous studies in Chile using passive sampling, we observed that the range of PCB levels in the urban air is similar to that at other locations in Latin American countries with the exception of the sampling sites at CON, where the industrial sites showed the highest concentrations (and the urban and rural sites showed similar levels) (Table S7). However, in a wider context, PCB levels in the Chilean urban air are generally lower in comparison with other urban areas of the world (Pozo et al., 2009). As expected, the highest PCB levels were detected at industrial and urban sites followed by rural areas (industrial N urban N rural) CON (CON6 site) N STG (STG1) N TEM (TEM4). In particular, high levels of PCBs were measured at the industrial site of Libertad (CON6) in the city of Concepción (Table S8); these high values are likely related to the intensive industrial activities in Concepción, such as integrated steel and coke production and activities in the industrial areas of Hualpén, San Pedro, Talcahuano, and Coronel; these sites are located ~ 5, ~ 7, ~ 12 and ~ 30 km from Concepción respectively (Pozo et al., 2012). Individual PCB congener patterns were different for the three cities (Fig. 1). Concepción had a greater proportion of the higher molecular weight PCB congeners. This combined with the higher levels of PCBs in Concepción, when compared to Santiago and Temuco, suggests a greater contribution from fresh emissions of technical PCBs that were captured at sampling sites in Concepción arising from potential industrial sources that have been discussed above. Across the three cities, the predominant PCB congeners were PCB-28 followed by -52. However, STG and TEM showed a different abundance of individual PCBs characterized by lower chlorinated PCBs i.e., PCB-28 (26%), PCB-52 (18%), and PCB-101 (15%). While, at Concepción, the higher chlorinated PCBs (PCB-138, -153, -180) accounted for 24% of the total [∑7PCB] (Fig. 1). Potential PCB sources at Santiago and Temuco are likely related to evaporation from urban surfaces and illegal disposal sites, while at Concepción the different PCB ﬁngerprint is likely inﬂuenced by the heavy industrial activities of the area. For instance, Concepción contains large industries including steel making and associated activities, in particular in the industrial area of Talcahuano (within 15 km of Concepciόn). PCBs are prohibited in Chile by Circular N° 2C/152 (1982) by the Ministerio de salud (MINSAL) (Ministry of Health). The
law is enforced by National Customs Service that regulates the import of PCBs as well as other toxic or hazardous substances. Under the PNUMA/FMNA project, additional information related to PCBs has been obtained recently through the “Regional diagnosis of PCBs management in the sector of Chile mining”. In this report, it was estimated that Regions II, VIII, and the Metropolitan Region have the highest amount of declared oils containing PCBs in use and stored throughout the country (Diagnóstico regional, 2013).
3.2. Organochlorine pesticides (OCPs) 3.2.1. HCHs (hexachlorocyclohexane: α- and γ-HCH) HCHs have been used in Chile since the early 1950s as a commercial insecticide in two formulations - technical HCHs and lindane. Technical HCHs is a mixture of several isomers of which α–HCH comprises 60– 70% and γ–HCH comprises 10–12% (Li et al., 2000), while lindane consists almost entirely of γ–HCH (Shen et al., 2004). In this study, ΣHCH concentrations were low at the studied cities ranging from ~ 1– 22 pg/m3 (Table 1). In particular, α-HCHs concentrations (pg/m3) in the air ﬂuctuated between 0.1 and 1 at Santiago, 0.1–0.6 at Concepción, and 0.1–1.5 at Temuco (Table S9). These results are generally lower, by a factor of 10 to 100, than those reported for urban areas in other Latin American countries and in selected studies around the world (Table S7). γ-HCH the main component of lindane was banned for agricultural use in Chile in 1998 but was still used in public health and pharmaceutical preparations for the treatment of sanitary and domestic diseases in humans and animals. In 2007, the Chilean Department of Health (MINSAL) prohibited its import, production, distribution, and commercialization (Pozo et al., 2012). The γ-HCH concentrations (pg/m3) ranged from 1 to ~ 20 at STG, 1 to ~ 22 at CON, and 1 to ~ 15 at TEM (Table S9), and showed similar concentrations at the three cities. These higher concentrations were recorded in the urban sites STG3 and STG2 (19 and 17 pg/m3), CON2 (22 pg/m3) and TEM4 (14 pg/m3) and are likely related to its utilization in public gardens or as secondary pharmaceutical treatment for human domestic diseases. Exemptions for such uses are allowed under the SC on POPs (Stockholm Convention, 2015) due to the low quantities employed in these applications. γ-HCH accounted for more than ~90% of the total HCHs composition at STG and CON and ~80% at TEM. This range of concentrations is similar
Fig. 1. Percent (%) composition of ∑7PCBs, HCHs, DDTs and the four major isomers of PBDEs during the four sampling periods in Santiago, Concepción and Temuco, Chile at rural, urban, and industrial sites.
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Fig. 2. Concentrations (pg/m3) of PBDEs in air in the Chilean cities of Santiago, Concepción and Temuco, over 4 sampling periods, during 2008–2009.
to values detected in previous studies in Chile and in other areas of Latin America as well as in other areas of the world (Table S7). The relative abundance of HCH isomers is expressed as α/γ-HCH. The α/γ-HCH ratio for technical HCHs mixture ranges from 4 to 7 (Shen et al., 2004). In this study, α/γ ratio of ~ 0.2 was observed at most sites, with the exception of Temuco where values of ~ 0.2–0.5 were detected. This low ratio reﬂects the prevalence of γ-HCH and the ongoing use of lindane (Fig. 1) (Pozo et al., 2012).
3.2.2. DDT (dichlorodiphenyltrichloroethane) Of the six DDT isomers analyzed for in this study, p,p′-DDT and p,p′DDE were the most frequently detected. ∑ DDTs (DDT + DDE)
concentrations (pg/m3) in the air ranged from 2 to 15 at STG, 1–30 at CON and 0.3–15 at Temuco (Table 1). In general, the highest levels were detected at the industrial and urban sites i.e., at Quilicura (STG1) in STG in central Concepción (CON2) and at Centro Temuco (TEM4). p,p′-DDE was the most abundant isomer and accounted for ~ 50% of the total DDTs, with the exception of central Concepción site (CON2) which showed a prevalence of p,p′-DDT (70% of DDTs (Fig. 1)). Comparing our results with other studies around the world, we observed that DDT levels were higher by a factor of 2–4 than the values found by Bogdal et al. (2013), at background sites across Latin American countries (b 1–4 pg/m) and by Estellano et al. (2008) in the Bolivian Andes. However, these values were similar to those reported in other studied areas i.e., Buenos Aires province in Argentina, b 0.1 to 20 (Tombesi et al., 2014); Cape Grim, Australia, f b BDL to 10; Stórhöfði, Iceland, b0.1 to 30; and in Barrow, Alaska, b0.1 to 20 (Pozo et al., 2009). Substantially higher levels of DDTs were reported in agricultural regions in India (Pozo et al., 2011), the Paciﬁc Islands as well as Africa (Bogdal et al., 2013) (Table S7). DDT was prohibited in Chile 30 years ago (1984); therefore its current levels may reﬂect unauthorized use of old stocks. To address this statement we assessed the relative abundance of parent DDT to its metabolite DDE, which has previously been established as a metric to distinguish “fresh inputs” (i.e. DDE/DDT b 1) from “aged signatures” (i.e. DDE/DDT N 1). In this study DDE/DDT ratios ranged from 2 up to 20 at Santiago and Temuco, suggesting that the DDT present in the atmosphere at the sampling sites originated from an ‘aged’ source of contamination. Interestingly, this ratio was much lower at Concepción, ﬂuctuating between ~2 to 5, with the exception of CON2 (Concepciόn central) showing a DDE/DDT ratio b 1, and suggesting a potential recent use of DDT. CON2 is located only 200 m from the Parque Ecuador which is a large tourist green area (with an area of 1 km), and is characterized by several native species of forest trees. In addition, chlorinated
Fig. 3. Box and whisker plots of the concentrations in air (pg/m3) of ∑7PCBs, ∑-47,-99,-100 PBDEs ∑HCHs, and DDTs in Santiago, Concepción and Temuco, over 4 sampling periods, from 2008 to 2009. The median is represented as a horizontal line in the boxes. The upper and lower extremities of the boxes indicate the 3th and 2th quartile, respectively. At either end of the boxes, the whiskers indicate the 1st and 99th percentile, and the circles (with the names of the speciﬁc sites) are the outliers that are N1.5 times the interquartile range.
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pesticides have been widely used in the central part of Chile (Biobío region) because of intensive industry (paper mills) and forestry activities (Pinus radiata and Eucalyptus plantations). Since DDT is prohibited in Chile, to identify other potential sources of DDTs we assessed the inﬂuence of the insecticide dicofol (Qiu et al., 2005; Li et al., 2014; Eng et al., 2016). Dicofol is a non-systemic organochlorine acaricide used in food, feed, and cash crops, including cotton, fruits, vines, ornamentals and vegetables. Dicofol is usually synthesized from technical DDT (Li et al., 2014), and DDT impurities in dicofol can represent a signiﬁcant current source of DDT to the environment. In technical dicofol, the o,p′-DDT/p,p′-DDT ratio ranges from 3 to 7 (Qiu et al., 2005) and this ratio can be tested against environmental data to assess potential DDT inputs from dicofol use. However, there is evidence of thermal degradation of p,p'Cl-DDT to p,p′-DDE (Qiu et al., 2005), leading to an increase in ambient concentrations of p,p′-DDE. In Chile, dicofol has been widely used in the wine industry, and is classiﬁed as Group IV, “unlikely to present acute hazard”; however, the WHO classiﬁed it as Group III, “slightly hazardous” (SAG, 2007). In 2007, there were 36,000 kg/L of dicofol sold in Chile (SAG, 2007). The o,p′-DDT/p,p′-DDT ratios calculated in Santiago and Concepción ranged from 0.6–2 (1.0 ± 0.3) and 0.5–1.2 (0.8 ± 0.2), respectively, suggesting a minimal inﬂuence of dicofol (Tables S10–S12). Interestingly, the rural site of STG5, that showed the highest values of the o,p′-DDT/p,p′-DDT ratio, also showed very high values of p,p′-DDE/p,p′-DDT ratios (11–19), suggesting some dicofol inﬂuence at this rural site. Moreover, at Temuco there was a prevalence of o,p′-DDT (~13%) with a o,p′-DDT/p,p′-DDT ratio of 0.6–8 suggesting some inputs from dicofol use in this area. This ﬁnding is also supported by the high p,p′-DDE/p,p′-DDT ratio (2−21).
3.3. PBDEs concentrations in air PBDE concentrations in air ranged from 1 to 55 pg/m3 at Santiago, from 0.5 to 20 pg/m3 at Concepción and from 0.4 to 10 pg/m3 at Temuco (Table 1, S13 and Fig. 2). The highest PBDEs levels were detected at the industrial sites at Quilicura (STG1) (~30 pg/m3, with one value as high as ~ 50 pg/m3), in Santiago, Indura (CON5) in Concepción (~ 20 pg/m3), and at the urban site of Temuco-Centro (TEM4) (Table S13 and Fig. 2). Comparing these results with other studies, we observe that PBDE levels in Chilean cities are similar to other areas of the world using similar sampling techniques (Table S14). Jaward et al., 2004 reported levels at European locations (0.5–250 pg/m3) with highest levels in the urban centers in mainland Europe: Milan, Bilthoven (Netherlands), Geneva, Athens, and Seville. PBDE levels detected in this study are similar to those reported in remote/background sites in Europe with values of approximately 0.5–10 pg/m3 (Iceland, Ireland, Norway, and Sweden) (Halse et al., 2011). Recently, Estellano et al. (2012) also detected relatively low levels of PBDEs (0.3–5 pg/m3) in Tuscany, Italy. We observed that urban and industrial sites showed similar patterns with a prevalence of PBDE-209, followed by PBDE-47 and PBDE-99 (Fig. 2). More speciﬁcally: in Santiago, the PBDE pattern composition was dominated by PBDE-209 accounting for 64% ± 23%, followed by PBDE47 accounting for 17% ± 12% and PBDE-99 with 10% ± 6% and the other with minor percentages (b 10%); at Concepción the composition was dominated by PBDE-209 accounting for 47% ± 26%, followed by PBDE-47 with 21% ± 10%, PBDE-99 with 20% ± 13%; and at Temuco by PBDE-209 (42% ± 37%) followed by PBDE-47 (27% ± 20%) and PBDE-99 (17% ± 13%) and minor percentages for the other isomers. In contrast, at rural sites PBDE-47 was dominant and accounted for 29% ± 7%, followed by PBDE-209 (29% ± 19%) and by PBDE-99 (24% ± 13%) (Fig. 2). The greater abundance of PBDE-47 as opposed to PBDE-209 at rural sites may reﬂect the greater atmospheric transport potential of the more volatile PBDE-47, whereas PBDE-209 is associated entirely with particles, and will tend to deposit closer to their respective sources (i.e. urban areas) (Besis and Samara, 2012).
The potential sources of PBDE in these Chilean cities are not well established. Since PBDEs are not manufactured in Chile, their presence is likely associated with their use as commercial mixtures in various intermediate processes, like ﬂame retardants and ﬁnished products- appliances, furniture, car seats, and a variety of electrical and electronic components. Landﬁlls and recycling facilities that contain PBDE-treated materials and electronic components are likely to be important emissions sources to the atmosphere (Besis and Samara, 2012). In Chile, it is estimated that approximately 176 k of electronic equipment waste is generated annually, with a generated rate per inhabitant of about 9.9 kg (Baldé et al., 2015). However, in recent years, Chile's Ministry of the Environment and private sector groups, such as “Chile Recicla” among others, have undertaken initiatives to promote integrated waste management. On April 04, 2016, the Chilean parliament approved a law for recycling that aimed at reducing the emission of waste residues of PBDEs in the environment. 3.4. Seasonal patterns The seasonal variation for all targeted chemicals is illustrated using a series of box and whisker plots (Fig. 3). The differences between the sampling periods did not show any comparable trend among the three cities. One-way ANOVA analysis indicated that none of the seasonal variations were signiﬁcant (p b 0.05) (Table S15). Seasonal differences are expected at the sampling sites due to changes in interannual seasonal conditions and their impact on emissions and air transport of the target chemicals. These meteorological inﬂuences will vary between the three cities due to differences in their local geography/topography and other factors such as human activity and the distance of sampling sites from coastal and agricultural areas. In order to assess seasonal concentrations, we recommended that air monitoring be carried out for extended periods (e.g. many years through long term studies to identify the time series of chemicals in the atmosphere) to capture several seasonal cycles. It may also be desirable to use shorter sampling periods e.g. 2–3 months, and/or to match the deployment periods of the passive samplers with the timing of the seasons at the individual sampling sites. In summary, this is the ﬁrst study that concurrently characterized the chemical composition of air samples in major urban areas of Chile. Large variability in the concentrations in air of targeted compounds was associated with emission sources (e.g. predominant industrial activities) and also the geographic and meteorological inﬂuences that were unique for each city and even among sites within the urban catchment. To better understand the impact of these factors more comprehensive and long term studies (e.g. more sites, shorter sampling periods) would be required. In addition, this information on the levels of POPs in major urban areas may be useful to initiate assessment of the inﬂuence of air pollution on the human population, in particular in highly populated sites throughout Chile. Overall, we observed that levels of PCBs were low in comparison to other studies carried out at sites in other geographic locations outside of Chile and Latin America. PBDE concentrations were higher in urban areas, in particular at STG, while organochlorine pesticides were more predominant at Concepción and Temuco, with dicofol identiﬁed as a potential new source of DDT in the central-southern regions of Chile. Acknowledgements The authors thank project Fondecyt 1161673 (PI: Karla Pozo) in Chile. This research was also supported by the National Sustainability Programme of the Czech Ministry of Education, Youth and Sports (LO1214) and the RECETOX Research Infrastructure (LM2015051). The authors thank Dr. Luis Diaz and Pablo Etcharren (Universidad Católica de Temuco) and Prof. Raul Morales and Patricio Jara (Universidad de Chile) for the logistical support provided during the sampling campaign.
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