Environ Sci Pollut Res (2014) 21:8284–8293 DOI 10.1007/s11356-014-2825-8
RESEARCH ARTICLE
Soil concentrations and source apportionment of polybrominated diphenyl ethers (PBDEs) and trace elements around a heavily industrialized area in Kocaeli, Turkey Banu Cetin
Received: 20 January 2014 / Accepted: 21 March 2014 / Published online: 1 April 2014 # Springer-Verlag Berlin Heidelberg 2014
Abstract Air pollutants are transported by dry deposition, wet deposition, and gas exchange accumulated in soil. Therefore, soil is an important environmental medium reflecting the level and the spatial distribution of air pollutants such as polybrominated diphenyl ethers (PBDEs) and heavy metals. Soil concentrations of seven PBDE congeners and 21 trace elements were determined in a heavily industrialized region (Dilovasi) in Kocaeli, Turkey. At all sites, Σ7PBDE concentrations ranged from 0.70 to 203 with a mean value of 26.3 μg kg−1 (dry weight). The congener profiles and mass inventories of PBDEs and their interactions with soil organic matter (SOM) were also investigated. BDE-209 was the dominant congener at all sites, followed by BDE-99 and/or -47. The estimated inventory of PBDEs for the Dilovasi district was 310 kg. However, there are several additional industrial regions in Kocaeli city. Considering the total land area, the potential inventory would be much larger for this city. The relationship between the PBDE concentrations in soil and SOM content indicated that factors other than soil properties have a greater influence on soil concentrations. Crustal enrichment factors (EFs) were determined; correlation analysis and factor analysis (FA) were also applied to generated data set to identify and apportion the sources polluting the soil. Sn, Mn, Ca, As, Zn, Pb, and Cd had significantly high average EF values, indicating that their soil concentrations were mainly influenced by anthropogenic activities. In FA, six factors were extracted with a cumulative variance of 84.4 % and industrial Responsible editor: Leif Kronberg Electronic supplementary material The online version of this article (doi:10.1007/s11356-014-2825-8) contains supplementary material, which is available to authorized users. B. Cetin (*) Department of Environmental Engineering, Faculty of Engineering, Gebze Institute of Technology, Kocaeli, Turkey e-mail:
[email protected]
activities and traffic were found to be the main factors affecting the soil profile. Keywords PBDEs . Trace elements . Factor analysis . Enrichment factor . Mass inventory
Introduction Soil is one of the most important environmental reservoirs of persistent organic pollutants (POPs). It is also a natural buffer for the transportation of these pollutants in different environmental compartments. Transfer of POPs between air and natural surfaces such as soil, water, and vegetation occurs especially through diffusive exchange, dry particle, and wet deposition. Once deposited, POPs tend to accumulate in soil for various periods of time and subject to partitioning, degradation, and transport processes depending on their physical– chemical properties (Cetin and Odabasi 2007a). In previous studies, it is pointed out that soil is an important environmental medium reflecting the level and the spatial distribution of POPs (Cetin and Odabasi 2007a; Cetin et al. 2007; Bozlaker et al. 2008a, b; Odabasi et al. 2009) and heavy metals (Guvenc et al., 2003; Yay et al., 2008) emitted from stationary and/or mobile air pollutant sources. Considering the technical, physical, and economical limitations of air sampling such as high financial costs and logistical requirements (e.g., need for electricity, trained operators) at several sites, it is tempting to use soil sampling to evaluate the level and spatial variation of air pollution (Odabasi et al., 2010). In the literature, similar trends, congener patterns, and spatial distributions were observed in soil and air concentrations of POPs (Li et al., 2010; Bozlaker et al., 2008a; Cetin and Odabasi 2007a, b) and their soil concentrations were used to evaluate the effects of local sources contributing to the air pollution (Meng et al., 2011; Odabasi et al., 2010; Bozlaker et al., 2008a).
Environ Sci Pollut Res (2014) 21:8284–8293
Polybrominated diphenyl ethers (PBDEs) are ubiquitous environmental pollutants. There has been great interest in these POPs in the past decade because of their persistence and probable toxicity and carcinogenic/mutagenic human health effects. PBDEs are likely to partition to solids (i.e., sediment, soil, atmospheric particles) and they may bioaccumulate when they are released into the environment. The accumulation of PBDEs on solids is driven by their relatively low water solubilities and vapor pressures, and relatively large octanol–water and octanol–air partition coefficients. Trace metals have also been investigated intensively for many years because of their similarly adverse environmental effects. The major sources of trace elements are industrial activities, traffic, and fossil fuel combustion. Trace elements are also deposited and accumulated in soil. Dilovasi is located at northwest of Turkey and is the center of a highly industrialized area by the Marmara Sea shoreline. The area contains several factories working on various sectors such as iron and steel industry, and paint, glass, wood and chemical industries. Transport facilities have enhanced with two motorways, railway, and many seaports. As a result of these industrial activities near the residential areas and heavy traffic, air pollution is one of the major environmental problems of the region that threatens public health seriously. The objective of this study was to investigate the levels of PBDEs and trace elements in soil and their spatial variations in the heavily industrial region, Dilovasi, Kocaeli, and to assess their possible sources. Soil samples were analyzed for seven PBDE congeners (BDE-28, -47, -99, -100, -153, -154, and -209) and 21 elements (Al, As, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, Sn, Sr, V, Zn). Spatial distribution of soil concentrations, crustal enrichment factors (EFs), factor analysis (FA), and correlation analysis were applied to evaluate the sources of PBDEs and trace elements.
Materials and methods Soil sampling The study area, Dilovasi, is a district of Kocaeli and is located at northwest of Turkey. It is the most industrialized area by the Marmara Sea shoreline (Fig. 1). There are 185 companies working on 45 different sectors including mainly iron–steel, aluminum, chemicals, paint, and energy such as the coal-fired electric power plant in the Dilovasi-organized industrial zone, which is located at the center of a bowl-like topographic structure. There are also many transport facilities with two motorways, railway, and many seaports. The residential areas
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among these industrialization and heavy traffic boost the magnitude of the public health problem. Previous studies have suggested that cancer became the major cause of death in the region (Arslan et al., 2013). Therefore, the area is intensely under the influence of anthropogenic activities, which makes it difficult to classify the area as industrial or urban. Soil texture classes were sandy clay loams in the study area (Gokbulak and Ozcan 2008). The prevailing wind directions are north, northwestern, and northeastern in the area. Soil samples were collected at 49 different points in the study area on September 2010 (Fig. 1). Several sub-samples (at least five) were taken over each sampling point and were integrated for analysis. Approximately 1-kg samples were collected manually from the upper 10 cm of soil. Sample preparation and analysis Samples were sieved through a 0.5-mm mesh to remove large particles and organic debris. They were sealed with airtight plastic bags and stored at −4 °C. The moisture content of soil was determined by weighing 30-g samples before and after drying at 103 °C in an oven for 24 h, and organic matter content was determined by loss on ignition in a muffle furnace at 600 °C for 4 h. All results were reported on a dry-weight basis. For elemental analysis, 0.5 g of sieved soil samples were extracted with 12 mL of concentrated acid (HCl/ HNO3, 3:1) in a microwave digester. Then, the samples were diluted to 50 mL with deionized water. For PBDE analysis, 5 g of soil samples were soaked overnight with a mixture of 1:1 acetone/hexane and were ultrasonically extracted for 60 min. Prior to extraction, all samples and blanks were spiked with PBDE surrogate standards (BDE77 and C13-BDE-209) to monitor the analytical recovery efficiencies. The volume of extracts were reduced and transferred into hexane using a rotary evaporator and a high-purity N2 stream. After concentrating to 2 mL, samples were cleaned up and fractionated on an alumina– silicic acid column containing 3-g silicic acid (deactivated with 4.5 % deionized water) and 2-g alumina (deactivated with 6 % deionized water). The column was pre-washed with 20-mL DCM followed by 20-mL petroleum ether (PE). Then, the sample in 2-mL hexane was added to the column and PBDEs were eluted with 35-mL PE. The final extracts were solvent exchanged into hexane and were concentrated to 1 mL under a stream of N2. Samples were analyzed for PBDEs with an Agilent 6890 N gas chromatograph (GC) equipped with a mass selective detector (Agilent 5973 inert MSD) working at negative chemical ionization (NCI) mode. The capillary column was DB5ms (15 m, 0.25 mm, 0.1 μm). The carrier gas (helium) was used at the constant flow mode (1.8 mL min−1) with a linear velocity of 70 cm s−1 The initial oven temperature was held at
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Environ Sci Pollut Res (2014) 21:8284–8293
Fig. 1 Map of the study area showing the sampling points and spatial distribution of PBDEs
90 °C for 1 min, raised to 340 °C at 20 °C min−1, and held for 2 min. The injector, ion source, and quadrupole temperatures were 280, 230, and 150 °C, respectively. High-purity methane was the reagent gas. PBDEs were analyzed in selected ion monitoring mode (SIM). For BDE-209, the bromine ions at m/ z 488.5 and 486.5 and for 13C-BDE 209 ions at m/z 496.5 and 498.5 were monitored. Compounds were identified based on their retention times, target, and qualifier ions, and were quantified using the internal standard calibration procedure. Elements in soil samples were analyzed with inductively coupled plasma optical emission spectrometer (ICPOES; Perkin Elmer DV-2100). The ICP-OES was calibrated daily using a certified standard solution. The analysis of samples was performed only if the r2 of calibration curve was >0.99. A calibration check solution was prepared by another certificated solution and the calibration curves were checked just after the initial calibration and for every 15 samples. If the deviation was more than ±10 %, the instrument was recalibrated. Further details of sample preparation and instrumental analysis could be found elsewhere (Cetin and Odabasi 2007a, b; Cetin et al. 2007; Bozlaker et al. 2008a, b; Odabasi et al. 2009).
Quality control All samples were spiked with surrogate standards (BDE-77 and C13-BDE-209) prior to extraction in order to monitor analytical recovery efficiencies. Average recoveries of BDE77 and C13-BDE-209 were 79±12 and 100±29, respectively. Instrumental detection limits were determined from linear extrapolation, based on the lowest standard in calibration curve and using the area of a peak having a signal/noise ratio of 3. The quantifiable PBDE amounts were between 0.05 (BDE-28) and 0.35 pg (BDE-209) for 1-μl injection. Blanks were also analyzed. The limit of detection of the method (LOD, nanogram) was defined as the mean blank mass plus three standard deviations (LOD=mean blank value+3 SD). Plastic bags were also analyzed for PBDEs. No quantifiable amounts were found indicating that using the plastic bags for sample storage was not a problem. Instrumental detection limit was used for the compounds that were not detected in blanks. Average analyte amounts in blanks were generally
