Chemosphere 185 (2017) 227e236
Contents lists available at ScienceDirect
Chemosphere journal homepage: www.elsevier.com/locate/chemosphere
Temporal and spatial variation of polychlorinated biphenyls (PCBs) contamination in environmental compartments of highly polluted area in Central Russia Natalia Malina*, Elena A. Mazlova Department of Industrial Ecology, Gubkin Russian State University of Oil and Gas, Leninskiy pr-t 65k1, 119991 Moscow, Russian Federation
h i g h l i g h t s The problem of the Serpukhov City (Russia) extreme contamination was not yet solved. PCBs migrate in the upper soil layers of the highly contaminated site. Water transport pathway plays a crucial role in PCBs migration in the studied region. Heptachlorinated biphenyls were found only in close proximity to the pollution source.
a r t i c l e i n f o
a b s t r a c t
Article history: Received 10 March 2017 Received in revised form 29 June 2017 Accepted 30 June 2017 Available online 2 July 2017
This study highlights the fact that serious contamination from polychlorinated biphenyls (PCBs) still exists in Serpukhov City (Russia). The research help to determine the temporal (16- and 24-year periods) and spatial PCBs distribution in the environmental compartments of the studied region. Samples of soil, sediments, water and plants were analysed in order to establish their contamination levels. The most recent data on the Serpukhov City's soil contamination showed that the PCBs concentrations varies from 0.0009 to 1169 mg/kg depending on the sampling point and the distance from the pollution source. The temporal trends of the contamination distribution with the soil depth showed contamination migration in the upper soil layers of the highly polluted site. The high level of water pollution (11.5 mg/L) in the proximity to the contamination source and the sediments contamination (0.098e119 mg/kg) were determined, as well as the water migration pathways of the PCBs that were prevalent in the studied region. The PCB congener group (by the level of chlorination) analysis showed that heptachlorinated biphenyls were only found in the soils in close proximity to the contamination place, while biphenyls with Cl 6 were found in the soil samples downstream of the condenser plant and with Cl 5 in the soil samples upstream of the plant. The plant uptake of PCBs, even on the extremely contaminated site, was shown. In turn, this research present new knowledge necessary for the development of a contaminated territory remediation strategy. © 2017 Elsevier Ltd. All rights reserved.
Handling Editor: J. de Boer Keywords: Polychlorinated biphenyls Environmental distribution Migration pathway Condenser plant Environmental pollution
1. Introduction The problem of environmental pollution involving toxic organic compounds is becoming increasingly important given the growing industrial impact. Currently, while the production and use of many organic pollutants are restricted or prohibited, some of them can be still identified in environmental samples. PCBs are good examples
* Corresponding author. E-mail address:
[email protected] (N. Malina). http://dx.doi.org/10.1016/j.chemosphere.2017.06.137 0045-6535/© 2017 Elsevier Ltd. All rights reserved.
of substances that were banned in terms of industrial usage a few decades ago, but they are still present in environmental compartments of different regions (Wang et al., 2016; Ali et al., 2015; Colombo et al., 2005; Eremina et al., 2016). This is not surprising, due to the properties of PCBs: long half-life in the environment, lipophilicity and capability to strongly accumulate on organic matter and lipids. Entering the environment or the food chain at the level of organisms, PCBs accumulate at higher chain levels in concentrations that are too high. PCBs were widely used in industry for many decades, despite the harmful properties of these substances to environment and the
228
N. Malina, E.A. Mazlova / Chemosphere 185 (2017) 227e236
numerous ways they could enter the environment (Sua et al., 2017; Cetin, 2016; Wang et al., 2015). Spills of PCB-containing liquids resulted in these substances entering natural cycles. This led to the formation of highly contaminated territories in different regions worldwide: for instance, Portsmouth (Ohio, USA) (Bowman et al.) and Serpukhov City (Russia) (Khakimov et al., 1998). Given the high level of PCBs toxicity in these polluted areas, remedial action is urgently needed. However, the first remediation step for contaminated areas should be to identify the scale of damage and the contaminants’ migration pathways. Many authors have contributed to the process of temporal and spatial trend identification with regard to PCB distribution. Bi et al. (2002) have determined the scale of PCBs migration in a paddy field in the WenTai area of China, finding that, even after six years of monitoring, the concentrations of PCBs in the soil were far from reaching uniform distribution. Lin et al. (2006) have described the mechanisms of PCB migration by constructing a simulated environment. However, the fate of contaminants in the real environment differs significantly from a simulated environment, as the distribution mechanisms are more complex (influenced by weather conditions, wind diagram, land topography, soil type etc.). Therefore, the continuous monitoring and understanding the pollutant distribution are important issues for each contaminated area. The monitoring of PCB contamination in soil, water, plant and biological samples of the Serpukhov region has shown that extremely high pollution levels have been prevalent in this area since 1988 (Khakimov et al., 2003; Surnina, 1992). Researches (Surnina, 1993; Pleskachevskaya and Bobovnikova, 1992) have also shown that the “CVAR” capacitor plant was the source of environmental contamination, due its use of PCB-containing mixtures (“Sovol” until 1969 and trichlorobiphenyl from 1968 to 1988). Authors (Khakimov et al., 2006; Sevostyanov et al., 2010) have determined that, between 1991 and 2006, soils of all the city regions were contaminated with PCBs despite the withdrawal of these substances from the technological processes at the plant. The last study on Serpukhov City's contamination (Demin, 2013) showed that the environmental problem remains unsolved and that extremely polluted sites can be still found in the city. Demin, 2013 have reported a decrease in PCB contamination levels in the territories to the north of the plant, but extremely high contamination levels of 26% in the territories to the south of the plant, that is more than 100 times the maximum residue limit (MRL ¼ 0.06 mg/kg) (GN 2.1.7.2511e09). However, Demin, 2013 have only determined the total PCB concentration without any specification of the congener groups' content. It should also be noted that this analysis of total PCBs concentration did not provide a full insight into the migration and degradation mechanisms of analytes, as only the pollution levels were established. Therefore, the objectives of this current study were to determine the temporal change in PCBs concentration in the Serpukhov region, to identify the spatial partitioning of contaminants in environmental compartments within extremely polluted area, to characterize the PCB migration pathways, and to specify the areas of high influence in the studied region.
Individual PCB congeners and internal standards were obtained from Dr.Ehrenstorfer, “Sovol” from Labtech (Moscow, Russia), hexane (99.85%) and acetone (99.85%) from Komponent reaktiv (Moscow, Russia). Milli-Q water was obtained by purification and deionization of tap water immediately prior to use with a Seralpur PRO 90 CN (Seral, Germany). 2.2. Sampling location and collection The study was carried in Serpukhov City (Moscow region). Soil, sediment, natural water and vegetation samples were collected from various types of urban areas, depths and distances from the condenser plant. Special attention was paid to the environmental samples taken from the area of the Serpukhov condenser plant (Fig. 1). Samples were taken during the summer of 2015 in dry weather. Table 1 in the Supplementary materials shows the coordinates of the sampling points, the depth and the samples types. The certificated methods were used for environmental samples
Table 1 Structures and names of PCB congeners used as standards. IUPAC name
Congener number
2-Chlorobiphenyl
1
2,3-Dichlorobiphenyl
5
2,4,5-Trichlorobiphenyl
29
2,20 ,4,6Tetrachlorobiphenyl
50
2,20 ,3,4,50 Pentachlorobiphenyl
87
2,20 ,4,40 ,5,60 Hexachlorobiphenyl
154
2,20 ,3,40 ,5,6,60 Heptachlorobiphenyl
188
2. Materials and methods 2.1. Standards and reagents The seven individual PCB congeners (IUPAC 1, 5, 29, 50, 87, 154 and 188) were used for calibration and PCBs mixture “Sovol” (Arochlor analogue) for the method bias determination. The chemical structures and the names of seven PCB congeners used as standards are listed in Table 1. A mixture of phenanthrene-d10 and chrysene-d12 was used as internal standards.
Structure
N. Malina, E.A. Mazlova / Chemosphere 185 (2017) 227e236
229
Fig. 1. Sampling points location.
analysis: Russian State Measurement System (GOST), federal environmental regulations (PND F) and international standards (US EPA). Soil sampling was carried out in accordance with GOST 17.4.4.02e84. A combined soil sample was prepared by mixing five spot samples from each sampling site and weighted more than 1 kg. Sediment sampling was carried out in accordance with GOST 17.1.5.01e80. Sediments samples were collected using a rod bottom sampler. Soil and sediment samples were collected in black glass jars with ground stoppers, transported to the laboratory in the refrigerator and stored at 4 C until analysis. The samples of soil and sediment were kneaded in a mortar before analyzing, followed by removing big inclusions (plant roots, insects, rocks, glass, etc.) and sieved through a 2 mm mesh sieve. The samples were not dried in order to avoid volatile compounds loss, but were mixed with a drying agent before analysis (sample: diatomaceous earth 4:1 wt.) to increase the solvent-soil particles’ contact area. The general characteristics of soil samples are presented in Table 2 in the Supplementary materials. Water samples were taken in accordance with GOST 318612012. Water samples were taken from the surface layer of the water body in 2 L glass bottles with screw caps, then transported to the laboratory in a refrigerator and stored at 4 C until analysis. The extraction of analytes was carried out for a period of 24 h after sampling. Plant material was sampled in accordance with GOST 27262-87.
Spot vegetation samples were taken from each soil sample site. The sampled plant species depended on the sampling point and comprised the majority of the plant cover in each specific sampling point. The plant species collected from each sampling point are listed in Table 1 in the Supplementary materials. A combined vegetation sample was prepared by mixing five spot samples from each sampling site and weighted more than 1 kg. The ground (stems, leaves) and underground (roots) plant parts were sampled in the sterile packages. Samples were cleared out of soil, dried at room temperature for 48 h, homogenized and stored at 4 C in a glass jar prior to analysis. 2.3. Samples extraction The extraction of solid samples was performed by accelerated solvent extraction (ASE 150 Thermo Scientific Dionex ASE 150) in accordance with EPA method 3545A. The hexane/acetone (1:1 v/v) mixture was used as a solvent. The extraction conditions were as follows: extraction temperature 100 C, pressure 10e14 MPa, a static cycle time 5 min, the solvent volume for filling the cell 60%, nitrogen purge cell 60 s at 1 MPa, number of static cycles 2. The extracts were prepared for chromatographic analysis according to methods EPA 3600C and EPA 3665A. Extracts were placed in a separatory funnel (250 ml) and 5 ml mixture of sulphuric acid/water (1:1 v/v) was added. The mixture was stirred and
230
N. Malina, E.A. Mazlova / Chemosphere 185 (2017) 227e236
allowed to stand for 5e10 min until the layers separated. The acid layer was then discarded and the organic layer was further cleaned with 5 ml of sulphuric acid. The procedure was repeated until the sulphuric acid layer became colourless. The purified extract was then washed with the distilled water to neutral pH. Purified and washed organic extracts were filtered through anhydrous sodium sulphate and evaporated to 1 ml at 65 C in a nitrogen stream in the TurboVap LV system. The prepared extracts were placed in a 2 ml hermetically sealed vial and stored at 4 C until analysis. The extraction of water samples was carried out in accordance with PND F 14.1:2:3:4.204e04. An unfiltered water sample (100 ml) was placed in an Erlenmeyer flask (250 ml) and sodium chloride was added before saturation. Next, 10 ml of hexane was added to the flask, with the sample placed on a horizontal shaker and stirred for 10 min at 80 rpm. The emulsion then stood for phase separation in a separating funnel; the hexane layer was filtered through anhydrous sodium sulphate and evaporated to 1 ml at 65 C in a nitrogen stream in the TurboVap LV system. The prepared extracts was placed in a 2 ml hermetically sealed vial and stored at 4 C until analysis. 2.4. Instrumental analysis The extracts were brought up to room temperature before chromatographic analysis. Analysis was performed on a gas chromatograph with mass spectrometric detection Bruker SCION SQ and conducted under the conditions listed below: evaporator temperature 280 C and splitless sample input. The GC oven temperature program started from 100 C (2 min) to 200 C at 10 C/min (10 min) and to 310 C at 5 C/ min (5 min). Helium was used as a carrier gas (gas flow rate: 1 ml/ min). The injected sample volume was 0.001 ml. The mass spectrometer detector parameters were as follows: electron ionization (70 eV); mass range 50e550 amu; interface temperature 270 C; 10 spectra/s. The HP-5MS capillary column nonpolar phase (5% phenyl 95% metylsiloxane) (length 30 m, internal diameter 0.25 mm and stationary phase film thickness of 0.25 mm) was used for separation
purposes. The detection of the analysed substances was performed in SCAN mode. The EPA 680 method was used to identify PCB as congener groups (i.e., by the level of chlorination). This approach has been fully described by Gebhart et al. (1985), Hong and Bush (1991) and proven to be a useful, reliable and cost-effective tool in cases of high PCB contamination of environmental compartments (AlfordStevens et al., 1986, 1988). A concentration was measured for each PCB congener group using the seven representative PCBs as standards, while total PCB concentration in each sample extract was obtained by summing the congener group concentration. The seven individual PCB congeners were used as concentration calibration compounds (IUPAC 1, 5, 29, 50, 87, 154 and 188) and represented the appropriate congener group. The individual response factors (RFs) of these individual PCBs was most similar to the group mean RF. One isomer at each level of chlorination was used as the concentration calibration standard for all other isomers at that level of chlorination. The response factor was calculated for each PCB calibration congener and surrogate compounds relative to both internal standards (phenanthrene-d10 and chrysene-d12). To obtain laboratory accuracy and precision data, the samples with known amounts of analytes were extracted and analysed (the “Sovol” mixture was used). As no true values are known for the concentration of PCB congener groups in the “Sovol” mixture, the mean measured total PCB concentration was determined using this approach, indicating a method bias of 9%. Qualitative analysis was performed according to the intensity of three characteristic ions of PCB congeners with the use of NIST library. The quantitative analysis was implemented using the main ion peak area. Analysis of environmental samples was performed using standard methods, with all data subjected to strict quality control procedures. Fig. 2 shows the chromatogram fragment of a highly contaminated soil sample. Blank samples were analysed with every batch of environmental sample. Limits of detection (LODs) for PCB congeners were determined by a signal-to-noise ratio (S/N) of three. In addition, the
Fig. 2. Total ion current of PCBs in highly contaminated soil sample (fragment): 1,2,6-diCB; 3e5,7-11,14,22-triCB; 12,13,15e21,23-30,32 e tetraCB; 31, 33e35 - pentaCB.
Table 2 PCB congener group concentration in environmental compartments of the Serpukhov City (average ± standard deviation; n ¼ 3). No
Sampling point
Distance from plant, m Altitude, m Sample type
1
Plant
20
145
Soil, mg/kg
2
Street Condensatornaya, 8
170
135
Grass, mg/kg Soil, mg/kg
125
River Nara bank
789
125
5.1 River Nara
789
125
7
Street Vesenaya
820
150
6
Street Moscovskaya
3620
165
8
Street Khimica
4200
160
4
5
135
Soil, mg/kg
0e10 10e20 20e30 e 0e10 10e20 20e30 30e40 40e50 50e60 e e e e
0e20 20e40 Grass, mg/kg e Soil, mg/kg 0e10 10e20 20e30 30e40 Grass, mg/kg e Sediments, mg/kg e Water, mg/L e Bulrush, mg/kg e Soil, mg/kg 0e10 10e20 20e30 30e40 Loosestrife creeping, mg/kg e Soil, mg/kg 0e10 10e20 20e30 Soil, mg/kg 20e30
Di
Tri
Tetra
Penta
Hexa
Hepta
0.0009 ± 0.0001 0.0033 ± 0.0005 N/D 0.015 ± 0.002 0.21 ± 0.03 6.3 ± 0.4 0.48 ± 0.05 0.38 ± 0.04 0.93 ± 0.08 1.1 ± 0.2 1.21 ± 0.01 0.29 ± 0.02 31 ± 8 6.2 ± 0.8
0.0057 ± 0.0005 0.0059 ± 0.0004 0.0004 ± 0.0001 0.23 ± 0.01 79 ± 4 295 ± 22 41 ± 2 9.4 ± 0.8 7.1 ± 0.1 4±1 77 ± 2 2.9 ± 0.2 74 ± 12 4.3 ± 0.7
0.0053 ± 0.0001 0.0041 ± 0.0002 N/D 0.34 ± 0.01 53 ± 1 794 ± 35 24 ± 4 7.8 ± 0.3 8±3 2.8 ± 0.6 162 ± 9 15 ± 2 13 ± 4 1.0 ± 0.01
0.0005 ± 0.0001 N/D N/D N/D 1.9 ± 0.1 65 ± 12 1.17 ± 0.04 1.12 ± 0.08 2.8 ± 0.1 0.30 ± 0.05 19 ± 1 0.093 ± 0.002 1.1 ± 0.3 N/D
N/D N/D N/D N/D 0.091 ± 0.004 8.0 ± 0.6 0.10 ± 0.02 0.26 ± 0.02 0.022 ± 0.005 0.04 ± 0.01 2.7 ± 0.3 N/D 0.15 ± 0.04 N/D
N/D N/D N/D N/D 0.032 ± 0.002 0.97 ± 0.08 0.031 ± 0.004 0.052 ± 0.003 0.091 ± 0.001 0.041 ± 0.001 N/D N/D N/D N/D
0.42 ± 0.06 15 ± 2 0.117 ± 0.002 0.23 ± 0.03 0.0020 ± 0.0003 0.00006 ± 0.00001 N/D N/D 0.021 ± 0.004 N/D N/D 0.0047 ± 0.0002 0.0045 ± 0.0001 0.012 ± 0.002 0.013 ± 0.003 N/D 0.0077 ± 0.0008 0.04 ± 0.01 0.0062 ± 0.0009 0.031 ± 0.006
2.9 ± 0.7 77 ± 8 0.83 ± 0.03 0.71 ± 0.02 0.017 ± 0.001 0.0017 ± 0.0001 0.0009 ± 0.0001 0.085 ± 0.003 0.07 ± 0.02
3.1 ± 0.4 8.3 ± 0.3 0.96 ± 0.03 0.41 ± 0.04 0.004 ± 0.001 0.00028 ± 0.00004 N/D N/D 0.007 ± 0.001
0.14 ± 0.01 1.0 ± 0.1 N/D 0.035 ± 0.007 N/D N/D N/D 0.009 ± 0.001 N/D
N/D 0.05 ± 0.01 N/D 0.012 ± 0.002 N/D N/D N/D N/D N/D
N/D N/D N/D N/D N/D N/D N/D N/D N/D
0.046 ± 0.002 0.054 ± 0.009 0.06 ± 0.02 0.09 ± 0.02 0.03 ± 0.01 0.11 ± 0.01 0.068 ± 0.006 0.16 ± 0.03 0.07 ± 0.01 0.05 ± 0.01
0.055 ± 0.001 0.17 ± 0.04 0.05 ± 0.01 0.06 ± 0.01 0.06 ± 0.01 0.020 ± 0.001 0.052 ± 0.006 0.138 ± 0.007 0.041 ± 0.008 0.09 ± 0.03
N/D 0.0028 ± 0.0004 N/D N/D 0.0025 ± 0.0008 N/D N/D 0.0115 ± 0.0006 N/D 0.004 ± 0.001
N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D
N/D N/D N/D N/D N/D N/D N/D N/D N/D N/D
N. Malina, E.A. Mazlova / Chemosphere 185 (2017) 227e236
170 Creek Borovlyanka (between sampling points St. Condensatornaya 8 and 10) Street 170 Condensatornaya, 10
3
Grass, mg/kg Goutweed, mg/kg Sediments, mg/kg Water, mg/L
Depth, cm PCB concentration
231
232
N. Malina, E.A. Mazlova / Chemosphere 185 (2017) 227e236
precision and relative standard deviation (RSD) were assessed by carrying out triplicate parallel extraction experiments. 3. Results and discussions 3.1. Spatial trends in PCBs congener groups distribution in the Serpukhov city (Russia) The data on the PCBs congeners group (by the level of chlorination) concentration in the environmental samples, distance from the sampling points to the plant and altitude are presented in Table 2. In general, the PCB contamination composition of the studied territory is characterized by a predominance of di-, tri- and tetrachlorobiphenyls in soil and sediments samples. The highest contaminations were determined for the sampling points « Street Condensatornaya, 8» and «Street Condensatornaya, 10». The water samples from Borovlyanka Creek (located between sampling points « Street Condensatornaya, 8» and «Street Condensatornaya, 10») contained di-, tri- and tetrachlorinated biphenyls in high concentration. It was also determined that the sediment composition taken from the creek was identical to the soil sample and contained biphenyls with a chlorination level of up to 6. Interestingly, heptachlorinated biphenyls were only detected in the most contaminated soil samples and not found in other samples. The soil sampled close to the plant territory (sampling point « Plant») contained low PCBs concentration levels. This may be explained by the physical properties of the soil sample, namely, its sandy soil type, which has a low sorption capacity of organic compounds. The analysis of the sampling point « River Nara bank» in terms of its distance from the plant territory showed high PCBs concentration levels in the surface soil (0e10 cm) and PCBs with a chlorination level of up to 6. The concentration 23-fold exceeds the MPL. A general tendency with regard to PCB concentration reduction was established by the depth of the soil profile, regardless of the chlorine number in molecules. An analysis of sediments from the River Nara showed their contamination with low-chlorinated biphenyls in a concentration that was 1.5-fold higher than the MPL. PCB contamination in the river water was not detected. The soil samples from the «Street Vesenaya», «Street Moscovskaya», «Street Khimica » sampling points at a distance from the territory of the plant contained di-, tri-, tetra- and pentachlorinated biphenyls. Interestingly, the environmental samples did not contain hexa- and heptachlorinated biphenyls in contrast with the sampling points located in the vicinity of the plant, namely the «River Nara Bank», «Street Condensatornaya, 8» and «Street Condensatornaya, 10». 3.2. Temporal trends and dynamics of PCBs in soil The results of the PCB redistribution in the soils of Serpukhov City over time are presented in Table 3: 16-year period (sampling point « Street Condensatornaya, 8») and 24-year period (other sampling points). The PCB concentration in the soil layers of the «Street Сondensatornaya, 8» sampling point, at a depth of 0e10 and 10e20 cm, increased after 16 years. At the same time, the concentration of the deep soil layers of this sampling point decreased significantly. An increase in PCBs concentration in surface soils was also established at the «River Nara bank » sampling point, located downstream of the condenser plant. Due to the complexity of the real environment, the reasons for such trend can include diffusion, volatilization, root uptake, and the capillary motion of water (McKone, 2009). Wide-ranging,
continuous monitoring is necessary to identify all the mentioned processes. Nevertheless, the plant could have played a major role in € hne et al., 2009; the contaminants’ uptake and migration (Ko Düring and G€ ath, 2002), while the analysis of the vegetation contamination from the sampling points could highlight the role played by the plants in the contaminants redistribution (Table 2). The analysis of the vegetation samples showed that all of the plant species contained PCBs. The grass from the «Street Condensatornaya, 8» sampling site contained high levels of di-, tri-, tetra-, penta- and hexachlorinated biphenyls. A high level of PCB concentration was also detected in goutweed; however, biphenyls with the chlorination degree higher penta were not detected in these plants. The total PCB concentration in grass samples of this sampling point exceeded the levels found in goutweed, although goutweed is the major plant found in this sampling point. Interestingly, heptaclorobiphenyls were not found in the plants of the «Street Condensatornaya, 8» sampling site. The similarity between the PCB congener's profile of soil and plant samples in the highly contaminated sampling points proved the crucial role played by vegetation in PCB distribution in this environment. Interestingly, the level of grass contamination from the «Plant » sampling point exceeded the levels found in the soil samples at different depths and were more contaminated than the plant samples from the «River Nara bank» and the «Street Veseniaya » sampling points, where the soil contamination levels were higher. This proves the low sorption of PCBs in this type of soil («Plant » sampling point). Another trend in the PCB temporal partitioning of the studied region was observed in remote sampling points: PCB concentration in the surface soil (0e10 cm) of the «Street Moscovskaya » sampling point decreased by a factor of 1.6, while the PCB concentration in the soil layer at a depth of 10e20 cm increased by a factor of 2.1. Thus, there was a migration of PCBs to the deeper horizons at this sampling point. The increase in concentration was determined for all soil horizons at the «Street Vesenaya» and «Street Khimica » sampling points. Analysis of the PCBs’ temporal dynamics at the «Street Condensatornaya, 10» sampling site was not possible because of the absence of extremely high pollution, as detected in 1991. Comparison of the obtained data on Serpukhov soil contamination and the PCBs half-lives (Mackay et al., 2006; Sinkkonen and Paasivirta, 2000) allowed us to analyse the detoxification rates of the contaminated areas. The average half-life periods of tri- and tetrachlorinated biphenyls in soil are six years. Thus, the remaining PCB concentration in contaminated soils should be 1/8 and 1/16 of the initial content for 16 and 24 years, respectively. However, such a contamination decrease was not determined in the studied sampling sites. It should be noted that the half-life values are set for systems with the absence of contaminant intake. Apparently, the situation is different in Serpukhov City, which confirms the presence of a permanent source of PCB intake in the environment of the studied region that has led to an increase in contamination in some soil horizons and the urgent character of the region's contamination problem. 3.3. Investigation of PCBs migration pathway in highly contaminated environment The altitude and the location of the sampling points were taken into account to identify the PCBs' migration pathway in the environment around the Serpukhov City (Fig. 3). It was assumed that both water and atmospheric migration pathways could have influenced the pollutants’ distribution. The physical properties of the individual congeners groups, which determine the contamination behaviour in the environment, and the PCB congener group concentrations were considered in
Table 3 Temporal trend in migration of PCBs in soils of the Serpukhov region.
234
N. Malina, E.A. Mazlova / Chemosphere 185 (2017) 227e236
Fig. 3. Sampling point location on the topographic map of the Serpukhov region.
establishing the migration routes. While analysing the contaminants’ behaviour in the polluted area, PCBs were divided into two groups according to their physical properties: biphenyls with a chlorine atom 4 and > 4. Thus, low chlorinated biphenyls (chlorine atoms 4) actively participate in evaporation deposition processes and mostly migrate with water flows due to their higher evaporation rates and water solubility. The highly chlorinated biphenyls (chlorine atoms >4) are more likely to adsorb on organic matter due to their larger hydrophobicity and sorption coefficients, meaning that the prevailing transport of these congeners with air flows are sorbed to dust particles (Hansen, 1999 and with water flows on the suspended solids (Steuer et al., 1999; Hites and Eisenreich, 1987). It was considered that atmospheric pollutants’ migration mechanism influences the contamination of the sampling points located higher up from the condenser plant, while both atmospheric and water pollutants migration mechanisms influence the contamination of the sampling points located at a low level to the condenser plant (Wania and Mackay, 1996). The participation of PCB migration in the water system was proven by the analysis of
water and sediment samples from the Borovlyanka Creek (Table 2), flowing from the plant territory. As sampling points N 4, 5 and 6 (Fig. 3) are located higher than the plant, the only possible way that pollutants can enter the environment is migration due to air flows. The influence of two migration types has led to the accumulation of both low- and high-chlorinated biphenyls at the sampling points located at the lower level to the plant territory (sampling points N 2 and 3). The « River Nara bank » sampling point, which was the lowest sampling point, confirmed the influence of two PCB migration mechanisms at long distances. Comparison of the lowest and highest sampling points' soil contamination («River Nara Bank» and «Street Moscovskaya») allowed us to determine the contribution made by each migration mechanism in the PCBs’ distribution in the studied region (Fig. 4). The aqueous migration mechanism was found to prevail for lowand high-chlorinated biphenyls in the studied region: 69% and 91%, respectively. Therefore, PCBs with a number of chlorine atoms >4 are more subjected to water transport (both dissolved and adsorbed on suspended matter) (IARC Monographs, 2016). This leads to
Fig. 4. Contribution of atmospheric and water migration mechanisms in the PCBs distribution in soils of the Serpukhov city.
N. Malina, E.A. Mazlova / Chemosphere 185 (2017) 227e236
increased exposure to major water bodies in Serpukhov: Rivers Nara, Rivers Oka and Lake Pavlensky. In turn, the water bodies’ contamination results in the entry of PCBs into the food chains of the ecosystems and affects public health.
235
Appendix A. Supplementary data Supplementary data related to this article can be found at http:// dx.doi.org/10.1016/j.chemosphere.2017.06.137. References
4. Conclusion Extreme levels of PCB contamination were identified in the environmental samples from the area of Serpukhov City in closest proximity to the condenser plant (1169 mg/kg). It was shown that the situation regarding the studied region's contamination is critical, due to the high contamination of soil samples. PCB concentration in the soils of some of the sampling points, located even at a long distance from the condenser plant, 2e7 fold exceeds the MPL. The general trends of PCB congener migration in the soils of the studied region can be characterized thus: 1. Heptachlorinated biphenyls could only be found in close proximity to the pollution source («street Condensatornaya, 8»), due to the high sorption capacity of these congeners in the soil aggregates. 2. The atmospheric transport involves PCB congeners with a number of chlorine atoms 5. 3. The water migration mechanism involves PCB congeners with a number of chlorine atoms in the molecule 6. The temporal dynamics of PCB soils contamination showed different migration trends in the sampling points located in close proximity and at a distance from the condenser plant. It was found that the flow of contamination in soil of the «Street Condensatornaya, 8» sampling point was as follows: 0e10 and 10e20 cm soil concentration increased 4.8 and 4.3 fold, respectively, and decreased in the deeper soil layers within a 16-year period. The same tendency was estimated in soil of the «River Nara » sampling point within a 24-year period. The contaminants redistribution in soil of the sampling points, located at a distance from the condenser plant, depends on the sampling point. Therefore, decrease in the upper and increase in the deeper layers were estimated in the soil of the «Street Moscovskaya » sampling point, while increase in all layers was determined in the soil of the «Street Vesenaya» and «Street Khimica » sampling points within a 24-year period. In general, no significant degradation of contamination was observed in the studied region over time. The areas of high environmental risk in the studied region were identified. They include the southern and western territories of the plant and major water sources, such as the River Oka. Our study on Serpukhov City's environmental pollution shows the need to develop remediation technologies. Due to the high level of soil contamination, the first step involving any complex remediation technology must be the excavation of soils with high PCB concentrations and further ex-situ treatment. Establishing a longterm continuous monitoring network of the studied region is also important in order to identify other possible highly polluted areas, as well as to obtain more data on PCB migration and distribution in highly polluted areas.
Acknowledgements The research was carried out in the framework of the state contract N 5.844.2014/K. We wish to thank Ivan Eremin (Gubkin Russian University of Oil and Gas) for the help with the sample collection and transportation.
Alford-Stevens, Ann L., Bellar, Thomas A., Eichelberger, James W., Budde, William L., 1986. Accuracy and precision of determination of chlorinated pesticides and polychlorinated biphenyls with automated interpretation of mass spectrometric data. Anal. Chem. 58, 2022e2029. Alford-Stevens, Ann L., Eichelberger, James W., Budde, William L., 1988. Multilaboratory study of automated determination of polychlorinated biphenyls and chlorinated pesticides in water, soil and sediment by gas chromatography/mass spectrometry. Environ. Sci. Technol. 22, 304e312. Ali, Usman, Syed, Jabir Hussain, Mahmood, Adeel, Li, Jun, Zhang, Gan, Jones, Kevin C., Malik, Riffat Naseem, 2015. Influential role of black carbon in the soileair partitioning of polychlorinated biphenyls (PCBs) in the Indus River Basin, Pakistan. Chemosphere 134, 172e180. Bi, Xinhui, Chu, Shaogang, Meng, Qingyu, Xu, Xiaobai, 2002. Movement and retention of polychlorinated biphenyls in a paddy field of WenTai area in China. Agric. Ecosyst. Environ. 89, 241e252. Bowman O.J., Lopez D., Kruse N., Migliore E., reportPreliminary Assessment of Polychlorinated Biphenyl (PCBs) Congeners, Aroclors, Dioxins and Furans in the Sediment and Soil at the United States Department of Energy Portsmouth Gaseous Diffusion Plant, Piketon, Preliminary PCB Assessment Report, 106 p. Cetin, Banu, 2016. Investigation of PAHs, PCBs and PCNs in soils around a heavily industrialized area in Kocaeli, Turkey: concentrations, distributions, sources and toxicological effects. Sci. Total Environ. 560e561, 160e169. Colombo, J.C., Cappelletti, N., Barreda, A.N., Migoya, M.C., Skorupka, C.N., 2005. Vertical fluxes and accumulation of PCBs in coastal sediments of the Río de la Plata estuary, Argentina. Chemosphere 61 (9), 1345e1357. Demin, D.V., 2013. PCBs Contaminated Soils Remediation. PhD thesis, p. 138. €th, Stefan, 2002. Tillage effects on the accumulation of Düring, Rolf-Alexander, Ga polychlorinated biphenyls in biosolid-amended soils. J. Plant Nutr. Soil Sci. 165, 299e304. EPA 3600C «Cleanup» EPA 3665A «Sulfuric Acid, Permanganate Cleanup» EPA 680. Determination of Pesticides and PCBS in Water and Soil/sediments by Gas Chromatography, Mass Spectrometry. EPA method 3545A «Pressurized Fluid Extraction (PFE) » Eremina, Natalia, Paschke, Albrecht, Mazlova, Elena A., Schüürmann, Gerrit, 2016. Distribution of polychlorinated biphenyls, phthalic acid esters, polycyclic aromatic hydrocarbons and organochlorine substances in the Moscow River, Russia. Environ. Pollut. 210, 409e418. Gebhart, Judith E., Hayes, Timothy L., Alford-Stevens, Ann L., Budde, William L., 1985. Mass spectrometric determination of polychlorinated biphenyls as isomer groups. Anal. Chem. 57, 2458e2463. GN 2.1.7.2511-09 « Maximum Residue Limit of Chemical Substances in Soil» GOST 17.1.5.01e80 «Nature Protection. Hydrosphere. General Requirements for Sampling of Bottom Sediments of Water Objects for Their Pollution Analysis» GOST 17.4.4.02e84 «Nature Protection. Soils. Methods for Sampling and Preparation of Soils for Chemical, Bacteriological, Helmintological Analysis» GOST 27262e27287 «Vegetable Feeds. Sampling Methods» GOST 31861e32012 «Water. General Requirements for Sampling» Hansen, L.G., 1999. The Ortho Side of PCBs: Occurrence and Disposition. Kluwer Academic Publishers Boston, Boston. Hites, R.A., Eisenreich, S.J., Eisenreich, S.J., 1987. In: Sources and Fates of Aquatic Pollutants, Advances in Chemistry 216. American Chemical Society, Washington, DC. Chapter 13. Hong, Chia-Swee, Bush, Brian, 1991. A new calibration method for mass spectrometric determination of polychlorinated biphenyls. Anal. Lett. 24 (6), 1017e1034. http://dx.doi.org/10.1080/00032719108054371. IARC, 2016. Monographs on the Evaluation of Carcinogenic Risks to Humans Polychlorinated Biphenyls and Polybrominated Biphenyls, vol. 107, p. 502. Khakimov, F.I., Deeva, N.F., Il’ina, A.A., 1998. Ecological and Geochemical Characteristics of Industrial City Soils, Ecology and Soils: Selected Lectures of I-VII Russian Schools, pp. 182e205. Khakimov, F.I., Deeva, N.F., Il’ina, A.A., 2003. Serpukhov city soil pollution with PCBs. Eurasian Soil Sci. 4, 493e498. Khakimov, F.I., Deeva, N.F., Il’ina, A.A., 2006. Soils of industrial city: transformation and pollution. Ecol. Noospherology 17, 24e40. €hne, John Maximilian, Ko €hne, Sigrid, Sim Ko unekc, Jirka, 2009. A review of model applications for structured soils: b) Pesticide transport. J. Contam. Hydrol. 104 (1e4), 36. Lin, Yaw-Jian, Liu, Hsiang-Chao, Hseu, Zeng-Yei, Wu, Wan-Jheng, 2006. Study of transportation and distribution of PCBs using an ecologically simulated growth chamber. Chemosphere 64 (4), 565e573. Mackay, Donald, Shiu, Wan Ying, Ma, Kuo-Ching, Lee, Sum Chi, 2006. Handbook of Physical-chemical Properties and Environmental Fate for Organic Chemicals, second ed. Taylor & Francis Group, p. 919. McKone, Thomas E., 2009. In: Thibodeaux, L.J., Mackay, D. (Eds.), Mass Transport within Soils, Environmental Mass Transfer Handbook, p. 48. Chapter 8.
236
N. Malina, E.A. Mazlova / Chemosphere 185 (2017) 227e236
Pleskachevskaya, G.A., Bobovnikova, Ts.I., 1992. Hygienic assessment of environmental contamination with chlorinated biphenyls. Hyg. Sanitation 7e8, 16e19. PND F 14.1:2:3:4.204-04 «Quantitative Chemical Analysis of Water. Measurement of Organochloride Pesticides and Polychlorinated Biphenyls in Drinking, Natural and Wastewater by Gas-chromatographic Method» Sevostyanov, S.M., Deeva, N.F., Il’ina, A.A., Demin, D.V., Shulzhenko, Yu.V., 2010. Spatio-temporal aspects of polychlorinated biphenyls distribution in soil of Serpukhov city. Proc. Samara Sci. Cent. Russ. Acad. Sci. 12 (1e1), 201e204. Sinkkonen, Seija, Paasivirta, Jaakko, 2000. Degradation half-life times of PCDDs, PCDFs and PCBs for environmental fate modeling. Chemosphere 40 (9e11), 943e949. Steuer, Jeffrey S., Hall, David W., Fitzgerald, Sharon A., 1999. Distribution and Transport of Polychlorinated Biphenyls and Associated Particulates in the Hayton Millpond, South Branch Manitowoc River, 1993e95. U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 99e4101. Sua, Peng-hao, Lv, Bao-yi, Tomy, Gregg T., Xu, Jin-xiang, Tian, Wen, Hou, Chun-yan, Yin, Fang, Li, Yi-fan, Feng, Dao-lun, 2017. Occurrences, composition profiles and source identifications of polycyclic aromatic hydrocarbons (PAHs),
polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in ship ballast sediments. Chemosphere 168, 1422e1429. Surnina, N.N., 1992. Observation of the Atmosphere in the Places of Environmental Pollution with Polychlorinated Biphenyls, Pollution of Soils of the Soviet Union with Industrial Toxicants in 1991: Yearbook. Part 2, pp. 238e243. Surnina, N.N., 1993. Assessment of Air Pollution in Some Cities and Regions of the Russian Federation with Polychlorinated Biphenyls. PhD thesis, p. 203. Wang, Guoguang, Peng, Jialin, Yang, Dandan, Zhang, Dahai, Li, Xianguo, 2015. Current levels, composition profiles, source identification and potentially ecological risks of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in the surface sediments from Bohai Sea. Mar. Pollut. Bull. 101 (2), 834e844. Wang, Pu, Shang, Hongtao, Li, Honghua, Wang, Yawei, Li, Yingming, Zhang, Haidong, Zhang, Qinghua, Liang, Yong, Jiang, Guibin, 2016. PBDEs, PCBs and PCDD/Fs in the sediments from seven major river basins in China: occurrence, congener profile and spatial tendency. Chemosphere 144, 13e20. Wania, F., Mackay, D., 1996. Tracking the distribution of persistent organic pollutants. Environ. Sci. Technol. 30, 390e396.
