Environmental pollution of soil with PAHs in energy producing plants zone

Environmental pollution of soil with PAHs in energy producing

plants zone

Svetlana Sushkova

⁎

, Tatiana Minkina

, Irina Deryabkina

, Vishnu Rajput

, Elena Antonenko

,

Olga Nazarenko

, Brijesh Kumar Yadav

, Erdogan Hakki

, Dinesh Mohan

a

Southern Federal University, Rostov-on-Don, Russia

b

Federal State Budgetary Institution of the Central Agrochemical Service“Rostovskyi”, ROSTOV Region, Rassvet Village, Russia

c

Indian Institute of Technology Roorkee, Roorkee, India

d

Selcuk University, Konya, Turkey

e_{School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India}

H I G H L I G H T S

• Soils of technogenic emission zone pol-luted by PAHs

• The levels and spatial distribution of PAHs were investigated.

• Total 16 PAHs content was studied for soils affected by energy producing plants.

• The content of higher molecular PAHs in soils increased under technogenic emis-sion.

• The PAHs concentrations rate in moni-toring sites depended on soil properties.

G R A P H I C A L A B S T R A C T

a b s t r a c t

a r t i c l e i n f o

Article history: Received 1 February 2018

Received in revised form 22 September 2018 Accepted 6 November 2018

Available online 7 November 2018

Polycyclic aromatic hydrocarbons (PAHs) are widely distributed environmental toxicants primarily formed dur-ing the incomplete combustion of organic materials (for example, coal, oil, gasoline and wood). Power energy plants are the main sources of organic contaminants including PAHs. The purpose of the present research was to study the Novocherkassk Electric Power Station (NEPS) emission effects of PAHs accumulation in soils. The re-gional levels, types (groups) and spatial distribution of 16 priority PAHs were investigated. The monitoring sites were located on fallow lands of the 20 km around NEPS. PAHs extraction from collected soil samples was per-formed using the ecologically clean express-method of subcritical water extraction. The total PAHs content grad-ually increased in soil of the studied territories during 2016–2017 due to an increase in contaminants emission. Accordingly 16 priority PAHs were determined in the soil samples collected from the sites located to the north-west from NEPS in direction of predominant winds. The 5-km zone situated in direction of predominant winds was highly subjected to PAHs contamination, with maximal accumulation at a distance of 1.6 km from the source. The ratio of high- and low-molecular weight PAHs content in soils of monitoring sites was taken as an index of environmental soil contamination. The high-molecular weight PAHs concentration prevailed in monitoring sites soils situated in direction of predominant winds from NEPS, while the concentration of low-molecular

Keywords:

Low-molecular weight PAHs High-molecular weight PAHs Environmental pollution Concentration rate PAHs monitoring Electric power station

⁎ Corresponding author at: 344090 Stachki prospect, 194/1, Rostov-on-Don, Russia. E-mail address:snsushkova@sfedu.ru(S. Sushkova).

https://doi.org/10.1016/j.scitotenv.2018.11.080

0048-9697/© 2018 Elsevier B.V. All rights reserved.

Contents lists available atScienceDirect

Science of the Total Environment

weight PAHs prevailed in the monitoring sites soils situated around NEPS. Soil properties also influenced PAHs accumulation. Polyarenes content in Haplic Chernozems and Haplic Chernozems (Stagnic) was higher versus Fluvisols. This study provides the understanding and model the fate of PAHs in regional technogenic landscape. © 2018 Elsevier B.V. All rights reserved.

1. Introduction

The regular monitoring of environmental toxicants accumulation and migration in the soil is very significant in soil science. Environment improvement of contaminated conditions is only possible after long-term monitoring studies. These studies are needed to identify contami-nation sources, nature, composition, mechanisms and diversity of trans-formation and accumulation of toxic compounds in the investigated biogeocenosis (Cristale et al., 2012; Tobiszewski and Namiesnik, 2012). One of the most effective ways for the technogenic contaminated territories remediation is possible by carrying out a large-scale and long-term monitoring and studying the speci_{ficity of contaminants} sorption and accumulation (Antizar-Ladislao et al., 2006;Augusto et al., 2013;T. Minkina et al., 2013;T.M. Minkina et al., 2013;Oros et al., 2007).

Polycyclic aromatic hydrocarbons (PAHs) belong to the one of the most significant groups of hydrophobic organic compounds affecting all living organism mutagenicity and carcinogenity ( Maliszewska-Kordybach et al., 2013;Tsibart and Gennadiev, 2013). Worldwide, 16 to 32 PAHs compounds are subject to mandatory control having a legis-lative regulation and depend on toxicants carcinogenicity, mutagenicity and toxicity (GOST 17.4.1.02.-83, 2004;GOST 14.4.3.06-86, 1986;Jian, 2004;Wenzl et al., 2006). These toxicants have been enumerated as the most priority toxicants by the US EPA as well as EU. PAHs mostly enter the environment from anthropogenic sources including fuel and organic compounds burning (Pereira et al., 2013).

The EU Thematic Strategy for Soil Protection (COM, 2006) defines the most affective threats to the soil ecosystem as a soil pollution con-ducing the direct and mediated risk for most of the soil functions (hab-itat, retention and production) (Maliszewska-Kordybach et al., 2008). PAHs pollution is caused by their persistence and hydrophobicity in en-vironmental objects especially with soil contamination due to the com-plex structure of the soil matrix (Antizar-Ladislao et al., 2006). The PAHs sorption and accumulation in soil mostly depend on soil matrix, PAHs physicochemical properties (Tsibart and Gennadiev, 2013). Soil organic matter is the main factor determining the PAHs sorption in soil (Gabov et al., 2010;Gennadiev and Tsibart, 2013;Maliszewska-Kordybach et al., 2010).

PAHs environmental contamination studies have been carried out by scientists of many countries for decades. Analysis of the number of publications devoted to investigations of ecological conditions in technogenic polluted region during PAHs contamination allowed to es-tablish the features of PAHs sorption mechanisms and research of effec-tive remediation methods (Callén et al., 2013;Pereira et al., 2013;Singh et al., 2013;Sushkova et al., 2015;Witter et al., 2014;Xing-hong' et al., 2006;Yam and Leung, 2013;Zhu et al., 2015). The PAHs presence in soils is caused by an increase in environmental pollution level. The most effective sources of PAHs environmental contamination include the power industry enterprises, and especially powerful thermal enter-prises (Witter et al., 2014;Yam and Leung, 2013). Agricultural produc-tion quality directly effects on human's exposure that caused a high actuality of PAHs accumulation by soils (Sosa et al., 2017). An enhanced understanding of the interrelated problems is important to prevent the risks associated with contamination of affected soils.

Novocherkassk Electric Power Station (NEPS) is one of the greatest thermal power enterprises in the European territory and Russia. It be-longs to I hazard class according the Russian law and it started officially in 1965 and actively working till to date. At present, the plant includes eight power blocks. Nine new blocks are under construction. The plant

is producing energy using the processing of organic raw materials. Coal is the major fuel type using at enterprise, so the electricity is pro-ducing through burning low quality coal. Main emissions are entering the environment through the chimneystacks. First of them has a height 185 m. Three other stacks are 250 m in height. NEPS belongs to the dom-inant contamination sources in the Southern Region in Russia, especially in Novocherkassk city. The enterprise provides a dominant contribution to the environmental contamination of the studied region. Rostov Re-gion is one of the main agricultural area in Russia. The land using regime in the studied area is mostly agricultural lands producing the next pop-ular agricultural crop as spring barley, winter wheat, sunflower, beans and others. As a result of the NEPS ash collectors' improvement, started in 2000, the share of the gas in total fuel volume since 2004 wasN40%. This contribution led to a decrease in the atmospheric total solid emis-sions volume up to 54 thousand tons per year. The total volume of atmo-spheric total solid emissions increased up to 83–101 thousand tons until 2011 (The ecological bulletin…,(Anon., 2012)). In 2016 and 2017 the total volume of NEPS emissions consisted 218–245 thousand tons, respectively.

The main composition of NEPS solid emissions include ash, nitrogen oxides, sulfurous oxide, carbon black (N30 tons year−1_{), iron oxide} (N5 tons year−1_{) vanadium pentoxide (N8 tons year}−1_{), chromic} anhy-dride (~0.1 tons year−1), and hydrogenfluoride (7 kg year−1_{). Up to 85%} ash of the solid emissions is retained from the enterprise (Gennadiev and Tsibart, 2013). It is estimated that about 10% of the total annual NEPS emissions are PAHs (Sushkova et al., 2015). It is well established that PAHs content in the ash can reach 60% (Gabov et al., 2010).

The territory of NEPS effect is under the current and previous studies (T. Minkina et al., 2013;T.M. Minkina et al., 2013;Sushkova et al., 2017). Atmospheric technogenic emissions of NEPS caused a high level of con-tamination of soils and plants by heavy metals as well as benzo[a] pyrene. The NEPS technogenic emissions contributed to high level accu-mulation of Cd2+_{, Cr}

T, Cu2+, Mn2+, Ni2+, Pb2+and Zn2+by the Poaceae and Asteraceae family's plants (Chaplygin et al., 2018). Soil and plant contamination by anthropogenic emissions from NEPS promoted the decrease in crop quality. Thus, soil and plant monitoring research re-ceives a special attention. Pb2+_{, Cd}2+_{, Cr}

T, and Ni2+contamination of soils and plants is growing near the power plant. The NEPS emissions af-fected the soil biological activity (Minnikova et al., 2017). It was shown the 5-km zone situated through the predominant wind direction from the enterprise was mostly contaminant by benzo[a]pyrene, a main marker of PAHs contamination. In the present investigation, 16 individ-ual PAHs concentration for studied territory of NEPS during 2016–2017 is presented. The aim of this research was to define the PAHs in the soil as well as the examination of the relationships by the emission factor parameters and natural conditions (soil properties). Previously, similar regional studies were not conducted.

2. Methodology

2.1. The study site characterization and soil sampling

The soils within the NEPS impact zone were the main target.Fig. 1

shows satellite images of the impact zone and the location of monitoring sites. The sites were located at the different distances around the NEPS (1–20 km) and coincided with air sampling sites of Novocherkassk city for governmental ecological monitoring (Belousova, 2001). Monitoring sites 1, 2, 3, 5, 6, 7, 11, 12 are found 1–3 km to the northeast, southwest, northwest, north and southeast from the electric power station; sites 8,

9, and 10 are located 5, 10, and 15 km to the northwest from the electric power plant in accordance with the wind rose controlling the distribu-tion of atmospheric emissions (Table 1). This zone stretches directly from the contamination source and crosses the residential areas of Krivyanskyi village and Novocherkassk city. Fallow land sites were taken as the monitoring sites.

Soil samples were collected annually in May or June during 2016–17. The samples were collected by layers, i.e., from the depth of 0–20 cm every year. The 5 samples were selected from every monitoring site by an envelope method for preparation of composite soil sample. Soils samples were processed for the chemical analysis following the State standards for soil sampling and sample preparation GOST 17.4.4.02-83 (GOST 17.4.1.02.-83, 2004) andGOST (State Standard) 17.4.4.02-84 (1984)requirements. The sampling was carried out by using a sterile metal spoon to the sterilized sampling bottle and transported to the lab-oratory in a cooler at temperature 4 °C. Samples were saved at perma-nent temperature in dark conditions until analysis for prediction of photochemical destruction of low-molecular weight PAHs. The data provided in the results was measured using the standard determination methods and same sample preparation procedure.

2.2. Soil properties and PAHs determination

Chemical and physics soil analyses were conducted using the air-dry soil samples stored in a room conditions (temperature 25 °C). All plant residues, root fragments, rocks larger 2 mm had been removed from soil

samples. The physicochemical properties were determined according to Methodological guidelines for the integrated soil fertility monitoring of agricultural lands(Anon., 2003). The particle-size distribution was stud-ied in the samples by Kachinskii method (Field and Laboratory_…,(Anon., 2001)). The organic carbon content in soils was determined by the Tyurin method (Arinushkina, 1970); pH in water extract (for the soil: water ratio equal to 1: 2.5), potentiometricallyGOST (State Standard) 26205-84 (1996); the cation exchange capacity (CEC) and the content of exchangeable bases Ca2+_{and Mg}2+_{by the Shaimukhametov method} (Shaimukhametov, 1993).

All PAHs analysis has been carried out no later than 1 month after sample collection. Using of modern PAHs analysis techniques allowed to absence of photo destruction and chemical oxidation of studied PAHs in soil samples to provide the high-quality results (ISO 13877-2005, 2005; EPA 8310). To identify the patterns of PAHs accumulation, it is necessary to select the effective environmentally friendly express-methods for determination of the toxicants in the soils. The develop-ment and application of alternative environdevelop-mentally green express-methods of PAHs extraction from soils is an urgent need in thefield of soil-ecological monitoring, restoration and protection of the environ-ment. The main factors in the determination of PAHs accumulation in soil is the use of ecologically clean methods for PAHs extraction. Extrac-tion by subcritical water is a method using the distilled water as an or-ganic compounds solvent at temperature range 100–374 °C (the critical point of water is 221 bar and 374 °C) and a pressure higher the saturated vapor pressure. This method has been used repeatedly for extraction of

Fig. 1. Monitoring sites in energy producing plants zone.

Table 1

Monitoring sites and their designations comprising the distance (in km), direction from the-NEPS, and soil type.

No. Designation Soil type No. Designation Soil

Sites located through the predominant wind direction from NEPS Sites located around NEPS

5 1.2nw Haplic Chernozem 1 1ne Haplic Chernozem

4 1.6nw Haplic Chernozem 7 1.5n Haplic Chernozem

8 5nw Fluvisols 6 2n Fluvisols

9 15nw Haplic Chernozem 3 2.7sw Fluvisols

10 20nw Haplic Chernozem 2 3sw Haplic Chernozems (Stagnic)

– – – 11 1.7se Haplic Chernozem

pollutants from environmental objects as soils and coals (Hawthorne et al., 2000), and for PAHs extraction from soils and food objects. Sub-critical water is of interest as an effective express method for extracting priority PAHs from contaminated soils, and also as an effective method for remediation of industrial contaminated areas by destruction of PAHs in contaminated soils (Chen et al., 2014;Islam et al., 2015).

A new subcritical water extraction method was used for PAHs deter-mination in the soil samples (Sushkova et al., 2014, 2016). The subcrit-ical water extraction method consists of the following steps: 1) the air-dry soil samples grounded in the porcelain mortar and sieved using 1 mm sieve; 2) in the extraction cartridge, 1 g soil sample and 8 mL double-distilled water were taken; 3) subcritical water extraction of polycyclic aromatic hydrocarbons from soil was accomplished in a stainless steel cartridge and closed by screw-on caps from both ends; 4) the extraction cartridge device holding soil sample with water was oven heated for 30 min (Lekar et al., 2013).

Subcritical water extraction was carried out at optimum extraction conditions (250°С, 55–60 atm and 30 min) (Galkin and Lunin, 2005;

Sushkova et al., 2015). The suspension was cooled and_{filtered using} Whatman no. 1 washed using 2 mL of double-distilled water. The oper-ation was repeated 2 to 3 times until clearfiltrate extract was obtained. The solution was 3-times re-extracted using 5 mL n‑hexane. The re-extraction was carried out by mixing it for 15 min followed by passing through a separatory funnel (ISO 13877-2005, 2005). Hexane extracts thus received were mixed andfiltered through anhydrous Na2SO4, after evaporated to dryness in a pear-shapedflask using rotary vacuum evaporator at 40 °С of water bath. The received extract was dissolved in 1 mL acetonitrile by carrying out 30 min shaking.

The PAHs concentration in the extracts was quantified using HPLC (Model 1260, Agilent Technologies, USA, 2014) with ultraviolet and fluorescence detection following the ISO 13877 requirements (ISO 13877-2005, 2005) and Agilent Application Solution_{“Analysis of PAHs} in soil according to EPA 8310 method with UV andfluorescence detec-tion” (EPA 8310, 2011) for HPLC determination and quantification. The PAHs peak on chromatograms was recognized by comparing reten-tion time to that of analytical standard samples. The PAHs detecreten-tion and quantification limit were calculated using calibration curves prepared taking standard solutions. A calibration standards chromatograms data were checked after analysis of every six samples for drift in retention time correction within a run. For the developed methods of the target PAHs extracting in the soil, it was estimated a random component of the measurement error, which for the concentration range of 2–200 μg kg−1_{was 3.5–14%.}

HPLC grade acetonitrile (99.9%, analytical grade), anhydrous Na2SO4, n‑hexane (99%, analytical grade), ethanol (96%, analytical grade), potas-sium hydrate (98%, analytical grade), and NaOH (97%, analytical grade), were used in the analysis. A total 16 priority PAHs standards in acetoni-trile with 200μg/cm3

concentration (Priority pollutant PAHs (in aceto-nitrile) NIST® SRM® 1647f) was used to prepare total PAHs standard solutions for HPLC analyses. For every target PAH, individual standard was used for determination: Naphthalene solution 200μg mL−1_(CAS Number 91-20-3, Beilstein Registry Number 7822574, MDL number MFCD00001742, PubChem Substance ID 329798455), Biphenyl solution 2000μg mL−1_{(CAS Number 92-52-4; 48161 SUPELCO), Anthracene} so-lution 200μg mL−1_{(CAS Number 120-12-7, Empirical Formula (Hill} No-tation) C14H10, Molecular Weight 178.23, Beilstein Registry Number 1905429, MDL number MFCD00001240, PubChem Substance ID 24872170), Acenaphthene solution 200_{μg mL}−1(CAS Number 83-32-9, Empirical Formula (Hill Notation) C12H10, Molecular Weight 154.21, Beilstein Registry Number 386081, MDL number MFCD00003807, PubChem Substance ID 24872166EC, Number 200-659-6), Acenaphthyl-ene certified reference material, TraceCERT® (CAS Number 208-96-8, Empirical Formula (Hill Notation) C12H8, Molecular Weight 152.19, Beilstein Registry Number 774092, MDL number MFCD00003806, PubChem Substance ID 329770136EC, Number 205-917-1), Fluorene so-lution 5000μg mL−1_{(CAS Number 86-73-7, Beilstein Registry Number}

3562815, MDL number MFCD00001111, PubChem Substance ID 24864952), Phenanthrene analytical standard, for environmental analysis (CAS Number 85-01-8, Empirical Formula (Hill Notation) C14H10, Molecular Weight 178.2, Beilstein Registry Number 1905428, MDL number MFCD00001168, PubChem Substance ID 24872118EC, Num-ber 201-581-5), Benzo(a)anthracene solution certi_{fied reference} material, 1000μg mL−1_{(CAS Number 56-55-3, Empirical Formula} (Hill Notation) C18H12, Molecular Weight 228.29, Beilstein Registry Number 1909298, MDL number MFCD00003599, PubChem Sub-stance ID 329755927), Pyrene solution certified reference material, 100μg mL−1_{(CAS Number 129-00-0, Empirical Formula (Hill} Nota-tion) C16H10, Molecular Weight 202.25, Beilstein Registry Number 1307225, MDL number MFCD00004136, PubChem Substance ID 57652921EC, Number 204-927-3), Fluoranthene 5000 μg mL−1 (CAS Number 206-44-0, Beilstein Registry Number 1907918, MDL number MFCD00001184, PubChem Substance ID 24864911), Chrys-ene analytical standard (CAS Number 218-01-9, Empirical Formula (Hill Notation) C18H12, Molecular Weight 228.29, Beilstein Registry Number 1909297, MDL number MFCD00003698, PubChem Sub-stance ID 329757387EC, Number 205-923-4), Benzo[a]pyrene solu-tion certified reference material, 200 μg mL−1_{(CAS Number} 50-32-8; Beilstein Registry Number 1911333; EC Number 200-028-5; MDL number MFCD00003602; PubChem Substance ID 24872109), Benzo(b)fluoranthene solution 200 μg mL−1_{(CAS Number} 205-99-2, Empirical Formula (Hill Notation) C20H1205-99-2, Molecular Weight 252.31, MDL number MFCD00010582, PubChem Substance ID 24871998, EC Number 205-911-9), Benzo(k)fluoranthene certified reference material, 200μg mL−1_{(CAS Number 207-08-9, Empirical} Formula (Hill Notation) C20H12, Molecular Weight 252.31, Beilstein Registry Number 1873745, MDL number MFCD00046287, PubChem Substance ID 329747589EC, Number 205-916-6), Benzo(g,h,i) perylene certi_{fied reference material, 200 μg mL}−1from 861,291 SUPELCO PAH Mix 3, certified reference material, in methylene chlo-ride: methanol (1:1) (varied) (CAS Number 191-24-2, Empirical For-mula (Hill Notation) C22H12, Molecular Weight 276.33, Beilstein Registry Number 1913029, MDL number MFCD00004135, PubChem Substance ID 24872193EC, Number 200-838-9), Dibenz(a,h)an-thracene analytical standard, 200μg mL−1_{(CAS Number 53-70-3,} Em-pirical Formula (Hill Notation) C22H14, Molecular Weight 278.35, Beilstein Registry Number 1912416, MDL number MFCD00003708, PubChem Substance ID 24872126EC, Number 200-181-8), purchased from the Sigma-Aldrich (Merch) was used as the internal analytical standard.

The efficiency of target PAHs extraction from soils was calculated using a spike matrix (Procedure of Measurements, 2008). The fresh and air-dried soil samples (1 g) were placed into a round-bottom flask. BaP standard solution prepared in acetonitrile was added to give the target PAHs concentrations of 2, 4, 6, 8, 16 or 32μkg kg−1_{. Solvent} was evaporated for 30 min under ambient conditions in a fume hood. PAHs-spiked soil samples were incubated at 4 °C for 24 h. The samples were then analyzed using the subcritical extraction method described above followed by HPLC analysis.

PAHs concentrations in soil samples (A,μg kg−1_{) were calculated as} follows:

A¼ k SI Cst V= Sð st mÞ

where Sstand SIare the respective areas of target PAHs peaks in chromatograms of standard and sample solutions, respectively; Cstis the target PAHs concentration in standard solution (μg mL−1_{); k is the} coefficient of target PAHs recovery from a sample; V is the acetonitrile extract volume used for HPLC (mL); and m is the sample mass (g).

Data handling and statistical analyses were carried out using STATISTICA 11.0 and Sigma-Plot 12.5. The total PAHs value means aver-age from 3 analytic replications. Statistical significance of the differences

among means was calculated using least significant difference (LSD) test. Differences were considered not significant at values of P N 0.05. 3. Results

3.1. Soil physicochemical properties

The major part of the territory in the impact zone of the NEPS is occu-pied by ordinary calcareous chernozems (Haplic Chernozems) (IUSS Working Group WRB, 2015); in addition, meadow-chernozemic soils (Haplic Chernozems (Stagnic)) and alluvial soils (Fluvisols) are distin-guished within the Tuzlov Rivernfloodplain (Table 2). Chernozems and meadow-chernozemic soils have deep humus horizons (70–100 cm), relatively high organic matter (2.2–2.9%) and the cation exchange capac-ity (CEC) (31.2–47.6 cmol+_kg−1_{) with a high exchangeable calcium} content (76_{–90% of the sum of exchangeable cations), and neutral to} weakly alkaline pH (7.3–7.7) in water extract. Based on particle-size dis-tribution, soils are classified as heavy loamy and light clayey formed on calcareous loess-like deposits with physical clay content 33_{–67% and} clay content 13–37%. The alluvial soils are specified by a coarser texture, less thick humus horizon (40–60 cm); CEC (10.6 cmol(+)/kg) with a rel-atively high exchangeable calcium content (84% of the sum of exchange-able cations) and low organic matter (up to 1.8%).

3.2. PAHs content

The study of PAHs content in 20 cm soil layer of monitoring sites lo-cated in the zone of NEPS aerotechnogenic impact showed intensive ac-cumulation of polyarenes in 2016 that increased in 2017. The 16 priority PAHs total concentration in 20 cm soil layer of monitoring sites in NS di-rection of predominant winds from NEPS was 1196,9 ± 17,0–1000,0 ± 17,0_{μg kg}−1in 2016 to 1514,1 ± 12,1_{–1196,9 ± 17,0 μg kg}−1in 2017 (Fig. 2A). A similar trend was observed at monitoring sites located in other directions from the source of emissions. The 16 priority PAHs total concentration was 580,8 ± 6,6μg kg−1_{in soil for monitoring} sites around NEPS in 2016 (Fig. 2B). It was observed the increase of PAHs total concentration for this sites up to 946,3 ± 7,4μg kg−1_{in 2017.} The data on PAHs total concentrations in 20 cm soil layer of mon-itoring sites around NEPS in 2016 and 2017 is provided atFig. 2B. The level of total PAHs concentrations varied from 383,3 ± 11,6μg kg−1 up to 842,5 ± 8,4μg kg−1_{in 2016 and from 600,3 ± 11,0μg kg}−1_up to 1135,2 ± 13,4_{μg kg}−1. The total PAHs content in monitoring site no. 5 (1,2 km w) was the highest for all sites around NEPS from 863,5μg kg−1_{up to 2168,0μg kg}−1_{that connected mostly on} loca-tion. Site no. 5 (1,2 km w) situated most close to the NEPS, but it is less affected compare to site no. 4 (1,6 km nw) caused by predomi-nant winds direction out of this site.

The data on PAHs composition in soil of monitoring sites in direction of predominant winds from NEPS in 2016 and 2017 is provided at

Figs. 3 and 4, respectively. It was found the content of high-molecular weight PAHs such as phenantrene, benzo[a]pyrene, pyrene, benzo(b)

fluoranthene and fluoranthene prevailed to low-molecular weight PAHs: naphthalene, biphenyl, anthracene, acenaphthene, acenaphthyl-ene,_{fluorene. The same data was found for monitoring sites around} NEPS (Figs. 5, 6).

4. Discussion

It was shown the PAHs accumulation in the soils of monitoring sites in direction of predominant winds depends mostly on distance to NEPS. The most affected monitoring site was no. 4 (1,6 km sw) with maximum PAHs concentration in 2017– 2352,9 ± 15,9 μg kg−1_{and in 2016} -1958,61 ± 23,0μg kg−1_{(Fig. 2А). A sharp increase of total PAHs content} in the soil of the monitoring site no. 8 (5,0 nw) from 1080,8 ± 12,1 μg kg−1_{in 2016 up to 1484,9 ± 16,9μg kg}−1_{in 2017 shows the territory} of environmental pollution from NEPS emissions reaches 5,0 km in the predominant wind direction. Dynamics of PAHs total concentration in 20 cm soil layer of monitoring sites showed the PAHs content decrease in site no. 9 (15,0 km nw) 760,7 ± 8,6μg kg−1_{in 2016 and 1091,0 ±} 10,4μg kg−1_{in 2017 and nearly the same contamination level of site} no 10 (20,0 km nw) 987,6 ± 11,7μg kg−1_{in 2016 and 1127,8 ± 16,2} μg kg−1_{in 2017 (Fig. 2). Thus, the most affected were sites no. 4} (1,6 km nw) and 8 (15,0 km nw).

At the same time, an increase in total PAHs accumulation including benzo[a]pyrene content was noticed in soils at a distance of 20 km (site no.10) from state district power station connected with a site prox-imity to the highway. This plot is located at 400 m from the highway, within a V-shaped area between two highways. Vehicle exhausts con-taminate by PAHs the soil at different wind directions (Hybholt et al., 2011).

Total content of high-molecular weight PAHs site no. 4 (1,6 km sw) reached up to 1240,7 ± 12,4μg kg−1_{in 2016 (Fig. 3) and 1627,9 ±} 18,7_{μg kg}−1in 2017 (Fig. 4) that showed a gradual increase of high-molecular weight PAHs during 2 years of monitoring. Low-high-molecular weight PAHs content was 717,9 ± 6,4μg kg−1_{in 2016 (Fig. 3) and} 725,3 ± 9,6μg kg−1_{in 2017 (Fig. 4). This tendency of high-molecular} weight PAHs content increasing and decreasing of low-molecular weight PAHs established the most prevalent way of PAHs input into the soil is technogenic emission by emitting ash residues from annealed coal from a thermal power plant. Also, as in previous years of benzo[a] pyrene content monitoring in the studied soils (Sushkova et al., 2014), the maximum PAHs accumulation is at the monitoring stations closest to the emission source in prevailing wind direction in the terrain. A sharp increase in PAHs content in the soil of the monitoring site no. 4 (1,6 nw) versus site no. 8 (5,0 nw) from 37% up to 45%, indicated the ter-ritory of the densest smoke plume containing maximum pollutant was about 5 km in the north-west direction, and the maximum deposition is taken place at a distance of about 1.6 km and decreased at a distance of 15 km from 62% to 54%.

The main pollution trend due to NEPS emissions were identified as the soil impact zone based on benzo[a]pyrene content reported in soils during 2008–2012 (Sushkova et al., 2014). Data analysis of

Table 2

Properties of NEPS emissions zone soils.

Monitoring sites no. Soil Physicalсlay (particle b0,01 mm), % Clay (particleb0,001 mm), % Corg, % pH CaCO3, % CEC, cmol (+)/kg

1 Haplic Chernozems 52 27 2,5 7,6 0,5 35,0

2 Calcaric Fluvic Arenosol 7 3 1,8 7,5 0,4 10,9

3 Haplic Chernozems (Stagnic) 67 37 2,7 7,3 0,2 44,8

4 Haplic Chernozems 55 29 2,7 7,5 0,7 31,2

5 Haplic Chernozems 53 27 2,5 7,5 1,0 35,7

6 Haplic Chernozems (Stagnic) 55 30 2,4 7,7 0,8 32,4

7 Haplic Chernozems 51 27 2,4 7,6 0,7 31,3

8 Haplic Chernozems (Stagnic) 60 32 2,9 7,4 0,4 47,6

9 Haplic Chernozems 52 30 2,4 7,6 0,6 31,4

10 Haplic Chernozems 53 28 2,7 7,6 0,5 36,0

11 Haplic Chernozems 33 15 2,2 7,5 0,6 38,7

Fig. 2. Dynamic of PAHs total concentration in 20 cm soil layer of monitoring sites (A) in direction of predominant winds from NEPS, (B) around NEPS in 2016–2017. Note: The meaning of the hanging bars is the average means standard deviation between three replications.

Fig. 3. PAHs concentrations in 20 cm soil layer of monitoring sites in direction of predominant winds from NEPS in 2016. Note: The meaning of the hanging bars is the average means standard deviation between three replications.

previous years established a number of compounds in soils which are widely varied. This is common worldwide (Cachada et al., 2014). Varia-tion in the BaP absolute values in soils adjacent to NPS during long-term period can serve as an index of different load of the NEPS, which worked at various power plants during the observations recorded in many years (Lipatov et al., 2015). Benzo[a]pyrene accumulation in the investigated steppe ecosystem occurred as a result of NEPS solid emission precipita-tion in the neighborhood and was dependent on the prevailing wind di-rection and soil properties (T. Minkina et al., 2013;T.M. Minkina et al., 2013). Similar benzo[a]pyrene accumulation trend (Figs. 3–6) was re-ported in NEPS affected zone during 2002–2012 (Sushkova et al., 2017), 2015 (Sushkova et al., 2018) and 2016–2017. Spatial variation in the benzo[a]pyrene content to a distance of 2 km northwards from

the Southern Sakhalin Power Plant revealed afivefold increase in benzo[a]pyrene content versus background. Similar studies of industrial enterprises territory on the priority PAHs accumulation in soils were re-ported (Callén et al., 2013;Gabov and Beznosikov, 2014;Tsibart and Gennadiev, 2013).

The benzo[a]pyrene accumulation in 20 cm soil layer has been re-corded in affected zone. These soils were collected from the territory where plots No. 4, 5, 8, 9, and 10 (Table 1) are located.

PAHs group composition in soils exposed to NEPS emissions has been established in 2016 (Figs. 3, 5) and 2017 (Figs. 4, 6). Mostly 3–5 ringed polyarenes including phenanthrene, pyrene, andfluoranthene prevailed in soils of studied territory in 2016 (Figs. 3, 5) and 2017 (Figs. 4, 6). Moreover, the high correlation coefficients were established

Fig. 4. PAHs concentrations in 20 cm soil layer of monitoring sites in direction of predominant winds from NEPS in 2017. Note: The meaning of the hanging bars is the average means standard deviation between three replications.

Fig. 5. PAHs concentrations in 20 cm soil layer of monitoring sites around NEPS in 2016. Note: The meaning of the hanging bars is the average means standard deviation between three replications.

between concentrations in the soils of monitoring sites located along the line of the prevailing direction of the wind rose, 0,91–0,83, respec-tively. It is caused by high level of anthropogenically contributed PAHs in the soils of studied territories. Consequently, PAHs accumulation in soils of studied territory depends on the impact of technogenic emis-sions of NEPS, as well as regional atmospheric pollution and PAHs input with atmospheric precipitation, are related to the receipt of PAHs from aerotechnogenic emissions of the enterprise (kindly revise). Significant annual fluctuations of PAHs concentrations in soil indi-cated the predominant role of PAHs microbial decomposition in the en-tire soil layer (Bacosa et al., 2013). Although PAHs photooxidation on the soil surface cannot be excluded (Bacosa et al., 2015), however, its contribution to the decomposition process is apparently minimal due to the screening of molecules adsorbed by soil and soot particles. It is well known that PAHs are persistent pollutants. Microorganisms are not able to use 4–5-nuclear PAHs as the carbon and energy sole source. Nevertheless, microbial degradation of high-molecular weight PAHs oc-curs under co-oxidative conditions in presence of microorganisms uti-lizing 2–3 nuclear PAHs, usually accumulated in contaminated soils as a result of soil micro_{flora adaptation (}Bacosa and Inoue, 2015). The abil-ity to accelerate the PAHs decomposition in the most contaminated soils has been explained by the accelerated adaptation of microorganisms in a selective factor presence (Bacosa et al., 2013). The decrease in rate of PAHs concentration in the insignificantly contaminated soils may be due to their low availability to biodestructors, This may be due to the strong adsorption by soil humus or pyrogenic particles (Gennadiev and Tsibart, 2013). However, the absence of a noticeable PAHs accumu-lation in soil, in spite of the continued soot deposition inflow in the NEPS impact zone, may also support the decomposition of the pollutant.

Soil enzymes dependence from PAHs contamination of soil was studied in 2015 (Sushkova et al., 2018). A very close dependence was recorded between PAHs concentration and biological activity parame-ters in the monitoring plots situated through the predominant winds. Dehydrogenases level in soils of monitoring plots in 2015 had a high positive correlation with biphenyl, acenaphthene and negative correla-tion with anthracene content. It means 2-rings low-molecular weight PAHs degraded in soils by dehydrogenase oxidation. This is one of the main enzymes increased in stressful organic contamination conditions using PAHs for metabolic oxidation process. Low-molecular weight PAHs are the most suitable substratum for enzyme activity, could be an easy power source for dehydrogenases in chernozem soil. Anthracene

concentration in studied soils doesn't exceed 21,2 ± 0,4μg kg−1_{, thus,} there is a probability of negative influence at dehydrogenase activity (Sushkova et al., 2018).

The PAHs concentrations rate in the sites located around NEPS de-pend more on soil properties versus location with respect to NEPS (Table 2,Figs. 5, 6). PAHs accumulation in soils was due to its low mobil-ity in zonal Haplic Chernozems and mostly Haplic Chernozems (Stagnic). This may be due to its low water solubility, high lipophilic properties and elevated absorption capacity by soil organics, the content of which is the maximal in thefine soil fraction and depends on the con-tent offine particles. In less humified light-textured soil, monitoring site 3 (2,7 km se) Fluvisols PAHs migration intensified noticeably. For exam-ple, total PAHs level in the nearest two sites 3 (2,7 km se) Fluvisols and 2 (3,0 km sw) Haplic Chernozems (Stagnic) differs mainly because of their soil types difference. Soil of monitoring site 3 (2,7 km se) pre-sented by Fluvisols (low-humus silty clayeyflood-plain meadow cher-nozemic soil on alluvial deposits) with physical clay content 67% that caused heavy clay granulometry absorbing PAHs molecules and lead to high accumulation level of this toxicants (Table 2). The PAHs concen-trations in Fluvisols were less compare to Haplic Chernozems (Stagnic) up to 13–40%. It is caused by low PAHs mobility and high accumulation rate in Haplic Chernozems (Stagnic) compare to sandy structure of Fluvisols allows to migrate PAHs through the soil profile (Figs. 4, 5) (Sushkova et al., 2017). The data obtained agreed with the results of in-vestigations showed the influence of soil particle-size distribution on the PAHs migration in natural and technogenic landscapes (Gabov et al., 2010;Gennadiev and Tsibart, 2013).

5. Conclusions

The toxic emission from the NEPS was one of the main factors of envi-ronmental pollution and PAHs accumulation in soils of the studied region. Soil properties were also the important factor for PAHs accumulation in studied region. For thefirst time, a total sixteen PAHs content was studied for 2 years for soils located in the NEPS zone. High-molecular weight PAHs concentration exceeded the low-molecular weight PAHs concentration at all monitoring sites located in direction of predominant winds from energy plant. Low-molecular PAHs concentration exceeded high-molecular weight PAHs concentration at monitoring sites situated around NEPS. It could be caused as high-molecular weight PAHs emissions, as strong biodegradation potential of the studied soils. A gradual PAHs

Fig. 6. PAHs concentrations in 20 cm soil layer of monitoring sites around NEPS in 2017. Note: The meaning of the hanging bars is the average means standard deviation between three replications.

increase in soils of the studied territories from 2016 to 2017 explained the increase in contaminants emission. Despite the environmental conserva-tion measures undertaken at the electric power staconserva-tion, the NEPS emis-sion into the atmosphere still exerts the strong effect on the ecological conditions in the adjacent areas. The territory of the densest smoke plume containing maximum PAHs concentration was about 5 km in the north-west predominant wind direction, and the maximum deposition was occurred at a distance of about 1.6 km and decreases at a distance of 15 km from 62% up to 54% in 2016 and 2017, respectively. The key var-iables affecting the PAHs accumulation in soils were the regional contam-inants emission and soil properties.

Acknowledgements

This research was supported by projects of Ministry of Education and Science of Russia, no. 5.948.2017/PCh, Russian Foundation for Basic Research, no. 16-35-60051, 16-05-00617a, Grant of the President of Russian Federation, no. MK-3476.2017.5, Leading Scientific School no. SSch-3464.2018.11. Analytical work was carried out on the equipment of Centers for collective use of Southern Federal University“High Tech-nology”, “Biotechnology, Biomedical and Environmental Monitoring”. References

Anon, 2001.In: Shein, E.V. (Ed.), Field and Laboratory Analysis of Physical Properties and Regimes of Soils: Methodological Guide. Moscow State Univ., Moscow.

Anon, 2003.Methodological Guidelines for the Integrated Monitoring of Soil Fertility of Agricultural Lands (Moscow 24 pp. [in Russian]).

Anon, 2012.The Ecological Bulletin of the Don“On the State of the Environment and Nat-ural Resources of the Rostov Region in 2011”. Rostov-on-Don: Rostov Region Admin-istration, Committee for Environmental Protection and Natural Resources (359 pp. [in Russian]).

Antizar-Ladislao, B., Lopez-Real, J., Beck, A., 2006. Degradation of polycyclic aromatic hydro-carbons (PAHs) in an aged coal tar contaminated soil under in-vessel composting con-ditions. Environ. Pollut. 141 (3), 459–468.https://doi.org/10.1016/j.envpol.2005.08.066. Arinushkina, E.V., 1970.Manual on the Chemical Analysis of Soils. Moscow State Univ,

Moscow (in Russian).

Augusto, S., Pereira, M., Máguas, C., Branquinho, C., 2013. PAHs for regulatory purposes. A step towards the use of biomonitors as estimators of atmospheric. Chemosphere 92, 626–632.https://doi.org/10.1016/j.chemosphere.2013.03.068.

Bacosa, H.P., Inoue, C., 2015. Polycyclic aromatic hydrocarbons (PAHs) biodegradation po-tential and diversity of microbial consortia enriched from tsunami sediments in Miyagi, Japan. J. Hazard. Mater. 283, 689–697.https://doi.org/10.1016/j.jhazmat.2014.09.068. Bacosa, H.P., Suto, K., Inoue, C., 2013. Degradation potential and microbial community structure of heavy oil-enriched microbial consortia from mangrove sediments in Okinawa, Japan. J. Environ. Sci. Health A 48, 835–846.https://doi.org/10.1080/ 10934529.2013.761476.

Bacosa, H.P., Erdner, D.L., Liu, Z., 2015. Differentiating the roles of photooxidation and bio-degradation in the weathering of light Louisiana sweet crude oil in surface water from the Deepwater horizon site. Mar. Pollut. Bull. 95, 265–272.https://doi.org/ 10.1016/j.marpolbul.2015.04.005.

Belousova, N.V., 2001.Ecology of Novocherkassk: Problems and Solutions. North Caucasus Scientific Center, Rostov-on-Don (395 pp.).

Cachada, A., Pereira, R., da Silva, E., Duarte, A., 2014. The prediction of PAHs bioavailability in soils using chemical methods: state of the art and future challenges. Sci. Total En-viron. 472, 463–480.https://doi.org/10.1016/j.scitotenv.2013.11.038.

Callén, M., López, J., Iturmendi, A., Mastral, A., 2013. Nature and sources of particle associated polycyclic aromatic hydrocarbons (PAH) in the atmospheric environment of an urban area. Environ. Pollut. 183, 166–174.https://doi.org/10.1016/j.envpol.2012.11.009. Chaplygin, V., Minkina, T., Mandzhieva, S., Burachevskaya, M., Sushkova, S., Antonenko, E.,

Kumacheva, V., Shipkova, G., 2018. The effect of technogenic emissions on the heavy metals accumulation by herbaceous plants. Environ. Monit. Assess. 190, 124–129.

https://doi.org/10.1007/s10661-018-6489-6.

Chen, H., Zhai, Y., Xu, B., 2014. Fate and risk assessment of heavy metals in residue from co-liquefaction of Camellia oleifera cake and sewage sludge in supercritical ethanol. Bioresour. Technol. 167, 578–581.https://doi.org/10.1016/j.biortech.2014.06.048. COM, 2006.Communication From the Commission of the Council, the European

Parlia-ment, the European Economic and Social Committee and the Committee of the Re-gions. Thematic Strategy for Soil Protection, 231final, 22 September 2006, Brussels.

Cristale, J., Silva, F., Guilherme, J., Rodrigues Marchi, M., 2012. Influence of sugarcane burning on indoor/outdoor PAH air pollution in Brazil. Environ. Pollut. 169, 210–216.https://doi.org/10.1016/j.envpol.2012.03.045.

EPA 8310, 2011.Agilent Application Solution“Analysis of PAHs in Soil According to EPA 8310 Method With UV and Fluorescence Detection”. Agilent Technologies, Inc. (Pub-lished in USA, Publication Number 5990-8414EN).

Gabov, D., Beznosikov, V., Kondratenok, B., 2010. Polycyclic aromatic hydrocarbons in the soils of technogenic landscapes. Geochem. Int. 48 (6), 569–579.https://doi.org/ 10.1134/S0016702910060042.

Gabov, D.V., Beznosikov, V.A., 2014. Polycyclic aromatic hydrocarbons in tundra soils of the Komi Republic. Eurasian Soil Sci. 47 (1), 18–25.https://doi.org/10.1134/ S1064229313110033.

Galkin,А., Lunin, V., 2005.Water in sub- and supercritical conditions is a universalfluid for implementation of chemical reactions. Success Chem. 74 (1), 24–40.

Gennadiev, A., Tsibart, A., 2013. Pyrogenic polycyclic aromatic hydrocarbons in soils of re-served and anthropogenically modified areas: factors and features of accumulation. Eurasian Soil Sci. 46 (1), 28–36.https://doi.org/10.1134/S106422931301002X. GOST (State Standard) 17.4.4.02-84, 1984.Nature Protection. Soils. Methods for Sampling

and Preparation of Soil for Chemical, Bacteriological, and Helminthological Analysis. Izd. Standartov, Moscow, p. 1984 (in Russian).

GOST (State Standard) 26205-84, 1996.Soils. Determination of Mobile Forms of Phospho-rus and Potassium by Machigin in Method Modified by CINAO, 1984. Izd. Standartov, Moscow (in Russian).

GOST 14.4.3.06-86, 1986.Nature Protection. Soils. General Requirements for the Classifi-cation of Soils in Accordance With the Impact of Chemical Pollutants on Them. Russian State Standard Publishing House (in Russian).

GOST 17.4.1.02.-83, 2004.State standard (Russian Federation State standard specifica-tion) Conservation. Soils. Classification of Chemicals for Pollution Control. Standards Publishing House Moscow (in Russian).

Hawthorne, S.B., Lagadec, A.J.M., Kalderis, D., Lilke, A.V., Miller, D.J., 2000.Pilot-scale de-struction of TNT, RDX, and HMX on contaminated soils using subcritical water. Envi-ron. Sci. Technol. 34, 3224–3228.

Hybholt, T.K., Aamand, J., Johnsen, A.R., 2011. Quantification of centimeter-scale spatial vari-ation in PAH, glucose and benzoic acid mineralizvari-ation and soil organic matter in road-side soil. Environ. Pollut. 159, 1085–1091.https://doi.org/10.1016/j.envpol.2011.02.028. Islam, M.N., Jung, H.-Y., Park, J.-H., 2015. Subcritical water treatment of explosive and heavy metals co-contaminated soil: removal of the explosive, and immobilization and risk assessment of heavy metals. J. Environ. Manag. 163, 262–269.https://doi. org/10.1016/j.jenvman.2015.08.007.

ISO 13877-2005, 2005.Soil Quality-Determination of Polynuclear Aromatic Hydrocarbons - Method Using High-performance Liquid Chromatography.

IUSS Working Group WRB, 2015.World Reference Base for Soil Resources 2014, Update 2015 International Soil Classification System for Naming Soils and Creating Legends for Soil Maps. World Soil Resources Reports No. 106. FAO, Rome.

Jian, Y., 2004. Photomutagenicity of 16 polycyclic aromatic hydrocarbons from the US EPA priority pollutant list. Mutat. Res. 557, 99–108.https://doi.org/10.1016/j. mrgentox.2003.10.004.

Lekar, A., Borisenko, S., Vetrova, E., 2013. Extraction of quercetin from Polygonum hydropiper L. by subcritical water. Am. J. Agric. Biol. Sci. 9 (1), 1–5.https://doi.org/ 10.3844/ajabssp.2014.1.5.

Lipatov, D.N., Shcheglov, A.I., Manakhov, D.V., Zavgorodnyaya, Y.A., Brekhov, P.T., 2015. Spatial variation of benzo[a]pyrene and agrozem properties in the vicinity of the Yuzhno-Sakhalinsk thermal power plant. Eurasian Soil Sci. 48 (5), 547–554.https:// doi.org/10.1134/S1064229315030084.

Maliszewska-Kordybach, B., Smreczak, B., Klimkowicz-Pawlas, A., Terelak, H., 2008. Monitoring of the total content of polycyclic aromatic hydrocarbons (PAHs) in ar-able soils in Poland Henryk. Chemosphere 73, 1284–1291.https://doi.org/ 10.1016/j.chemosphere.2008.07.009.

Maliszewska-Kordybach, B., Klimkowicz-Pawlas, A., Smreczak, B., Stuczyński, T., 2010. Re-lationship between soil concentrations of PAHs and their regional emission indices. Water Air Soil Pollut. 213, 319–330.https://doi.org/10.1007/s11270-010-0387-z. Maliszewska-Kordybach, B., Smreczak, B., Klimkowicz-Pawlas, A., 2013. The levels and

composition of persistent organic pollutants in alluvial agriculture soils affected by flooding. Environ. Monit. Assess. 185 (12), 9935–9948.https://doi.org/10.1007/ s10661-013-3303-3.

Minkina, T., Sushkova, S., Mandzhieva, S., 2013a. Monitoring researches of the benzo[a] pyrene content in soils under the influence of the technogenic zone. Middle East. J. Sci. Res. 17 (1), 44–49.https://doi.org/10.5829/idosi.mejsr.2013.17.01.11241. Minkina, T.M., Motuzova, G.V., Mandzhieva, S.S., Nazarenko, O.G., Burachevskaya, M.V.,

Antonenko, M., 2013b. Fractional and group composition of the Mn, Cr, Ni, and Cd сompounds in the soils of technogenic landscapes in the impact zone of the Novocherkassk Power Station. Eurasian Soil Sci. 46 (4), 375–385.https://doi.org/ 10.1134/S1064229313040108.

Minnikova, T.V., Denisova, T.V., Mandzhieva, S.S., Kolesnikov, S.I., Minkina, T.M., Chaplygin, V.A., Burachevskaya, M.V., Sushkova, S.N., Bauer, T.V., 2017. Assessing the effect of heavy metals from the Novocherkassk power plant emissions on the bi-ological activity of soils in the adjacent areas. J. Geochem. Explor. 174, 70–78.https:// doi.org/10.1016/j.gexplo.2016.06.007.

Oros, D., Ross, J., Spies, R., Mumley, T., 2007. Polycyclic aromatic hydrocarbon (PAH) con-tamination in San Francisco Bay: a 10-year retrospective of monitoring in an urbanized estuary. Environ. Res. 105, 101–118.https://doi.org/10.1016/j.envres.2006.10.007. Pereira, T., Laiana, S., Rocha, J., Broto, F., Comellas, L., Salvadori, D., Vargas, V., 2013.

Toxicogenetic monitoring in urban cities exposed to different airborne contaminants. Ecotoxicol. Environ. Saf. 90, 174–182.https://doi.org/10.1016/j.ecoenv.2012.12.029. Procedure of measurements of benzo[a]pyrene content in soils, sediments, and sludges

by highly effective liquid chromatography method. Certificate 27-08, Moscow, 56 p., (in Russian).

Shaimukhametov, M.Sh., 1993.Determination of consumed Ca and Mg in chernozems. Pochvovedenie 12, 105–111.

Singh, D., Gadi, R., Mandal, T., Saud, T., Saxena, M., Sharma, S., 2013. Emissions estimates of PAH from biomass fuels used in rural sector of Indo-Gangetic Plains of India. Atmos. Environ. 68, 120–126.https://doi.org/10.1016/j.atmosenv.2012.11.042. Sosa, B.S., Porta, A., Lerner, J.E.C., Noriega, R.B., Massolo, L., 2017. Human health risk due to

variations in PM10-PM2.5 and associated PAHs levels. Atmos. Environ. 160, 27–35.

Sushkova, S., Vasilyeva, G., Minkina, T., Mandzhieva, S., Tjurina, I., Kolesnikov, S., Kizilkaya, R., Askin, T., 2014. New method for benzo[a]pyrene analysis in plant material using subcritical water extraction. J. Geochem. Explor. 144 (Part B), 267–272.https://doi. org/10.1016/j.gexplo.2014.02.01.

Sushkova, S., Minkina, T., Mandzhieva, S., 2015. Approbation of express-method for benzo [a]pyrene extraction from soils in the technogenic emission zone territories. Eur. J. Soil Sci. 4 (1), 15–21.https://doi.org/10.18393/ejss.48158.

Sushkova, S.N., Minkina, T.M., Mandzhieva, S., Vasilyeva, G., Borisenlo, N., Turina, I., Bolotova, O., Varduni, T., Kizilkaya, R., 2016. New alternative method of benzo[a] pyrene extraction from soils and its approbation in soil under technogenic pressure. J. Soils Sediments 16 (4), 1323–1329.https://doi.org/10.1007/s11368-015-1104-8. Sushkova, S., Minkina, T., Turina, I., Mandzhieva, S., Bauer, T., Kizilkaya, R., 2017. Monitoring

of benzo[a]pyrene content in soils under the effect of long-term technogenic pollution. J. Geochem. Explor. 174, 100–106.https://doi.org/10.1016/j.gexplo.2016.02.009. Sushkova, S., Minkina, T., Deryabkina (Turina), I., Mandzhieva, S., Zamulina, I., Bauer, T.,

Vasilyeva, G., Antonenko, E., Rajput, V., 2018. Influence of PAHs contamination on soil ecological status. J. Soils Sediments 18 (6), 2368–2378.https://doi.org/10.1016/ j.gexplo.2016.02.009.

Tobiszewski, M., Namiesnik, J., 2012. PAH diagnostic ratios for the identification of pollu-tion emission sources. Environ. Pollut. 162, 110–119.https://doi.org/10.1016/j. envpol.2011.10.025.

Tsibart, A., Gennadiev, A., 2013. Polycyclic aromatic hydrocarbons in soils: sources, behav-ior, and indication significance. Eurasian Soil Sci. 46 (7), 728–741.https://doi.org/ 10.1134/S1064229313070090.

Wenzl, T., Simon, R., Anklam, E., Kleiner, J., 2006. Analytical methods for polycyclic aro-matic hydrocarbons (PAHs) in food and the environment needed for new food legis-lation in the European Union. Trends Anal. Chem. 25 (7), 716–725.https://doi.org/ 10.1016/j.trac.2006.05.010.

Witter, A., Nguyen, M., Baidar, S., Sak, P., 2014. Coal-tar-based sealcoated pavement: a major PAH source to urban stream sediments. Environ. Pollut. 185, 59–68.https:// doi.org/10.1016/j.envpol.2013.10.015.

Xing-hong', L., Ma, L.-l., Li, X.-f., Fu, X., Cheng, H.-x., Xu, X.-b., 2006. Polycyclic aromatic hy-drocarbon in urban soil from Beijing, China. J. Environ. Sci. 18 (5), 944–950.https:// doi.org/10.1016/S1001-0742(06)60019-3.

Yam, R., Leung, W., 2013. Emissions trading in Hong Kong and the Pearl River Delta region —a modeling approach to trade decisions in Hong Kong's electricity industry. Environ. Sci. Pol. 31, 1–12.https://doi.org/10.1016/j.envsci.2013.03.010.

Zhu, Y., Yang, L., Yuan, Q., Yan, C., Dong, C., Meng, C., Sui, X., Yao, L., Yang, F., Lu, Y., Wang, W., 2015. Airborne particulate polycyclic aromatic hydrocarbon (PAH) pollution in a background site in the North China Plain: concentration, size distribution, toxicity and sources. Sci. Total Environ. 466–467, 357–368. https://doi.org/10.1016/j. scitotenv.2013.07.030.