ATMOSPHERIC
ENVIRONMENT

PERGAMON

www.elsevier.com/locate/atmosenv

Internal-combustion engines especially jets are known to be important industrial sources of benz(a)pyrene (BaP) to the environment. Over 30 years, jet aircraft have been operating in the vicinity of the town Monchegorsk, situated far north of Russia (Kola peninsula, 68°N and 33°E). The jet aircrafts take off from the military aerodrome located 4 km from the town. The takeoff path is over the inhabited territory of the town. It has been determined that the content of BaP in the upper organic soil layer varied from 200 to 30 ppb along the main path of the takeoff. These concentrations of BaP are 40-6 times larger than background levels and are 10-1.5 times larger than the accepted threshold concentration. The polluted zone correlates with the trajectory of the plane takeoff. The concentration of BaP in the berries of Vaccinium Vitis-idaea and Empetrum Hermaphroditum seems to be independent of B(a)P concentration in soil. © 2000 Elsevier Science Ltd. All rights reserved.

Keywords: Benz(a)pyrene; PAH; Soil; Berry; Jet

1. Introduction

Polycyclic aromatic hydrocarbons (PAH) are known to be extremely dangerous as they are carcinogens and mutagens on one hand and are widely spread in the environment on the other (Shabad, 1973; Suess, 1976; Bjorseth and Rahmdahl, 1985; Nikolaou et al., 1984; Rovinsky et al., 1988; IARC, 1977,1983; Aamot et al, 1996; Golomb et al, 1997; Laflamme and Hires, 1978).

There are both natural and anthropogenic sources of PAH in the environment. The industrial processes for heat treatment of organic raw materials (coking and petrochemistry), ferrous and non-ferrous metallurgy, the combustion of organic matters, i.e. stoves, furnaces, internal-combustion engines and also burning dumps and incinerators are the anthropogenic sources of PAH. Jet and turbo-jets engines form zones with elevated concentrations PAH on aerodromes and in the areas around them (Shabad and Smirnov, 1969; Smirnov, 1970). Prairie and forest fires (Rovinsky et al, 1988), volcanoes (Ilnitsky et al, 1977; Florovskaya et al, 1978); some hydrothermal phenomenon and hydrocarbon anomalies of tectonic active zones (Florovskaya, 1975; Blumer, 1976) are known to be the main natural sources of RAH existing in the environment. Many PAH are known to be carcinogens and mutagens, but benz(a)pyrene (BaP) is considered to be the most carcinogenic. Only 1.2-5.6 dibenzo-anthracene, not so widely spread in the environment, has comparable harmful affect. Therefore, BaP is usually chosen as an indicator of environmental contamination by PAH. There is evidence to suggest that carcinogenic influence of BaP from the point of view of the development of lung cancer is equivalent to the influence of radioactivity. (Israel et al, 1992). The indicator role of BaP is also explained by the relative ease of its identification by clear spectra of low temperature (77 K) fluorescence (Shpolsky effect conditions) - (Nak-himovsky et al, 1989). BaP is accumulated from the ambient air by the soil and absorbed in the upper organic layer (Shabad, 1973; Jones et al., 1989; Gennadiev et al., 1997; Johnes, 1989a,b).

BaP is absorbed by plants via roots (Hancock et al, 1970; Slepyan, 1979; Thomas et al, 1984). Mosses and lichens actively accumulate BaP evidently directly from air (Carlberg et al, 1983). The accepted background BaP concentration in the soil is 1-5 ppb, in the plants — 1 ppb (Rovinsky et al, 1988). The accepted maximum tolerable concentrations of BaP in Russia are (Rovinsky et al, 1988): in soils - 20 ppb, in water - 0.005 ug/1, in urban air — 0.1 ug/100m3, in air in the proximity of industrial activity - 15 ug/100 m3.
The goal of the present study was to determine the level of the BaP in the soil and berries in the zone of the jet aircraft take off and to determine whether elevated levels can be attributed to jet activity.

2. The site

The region under investigation is the Kola peninsula, 68⁰N and 33⁰E. It includes the area of the town of Monchegorsk and its surroundings and the eastern and south-eastern territory of the Lapland Biosphere Reserve as well.

2.1. Climate

The climate of the region is maritime subarctic with a mean annual temperature of — 2⁰C. Winter is long (about 200 days) and cold: the average temperatures in January range from — 9⁰ to — 6⁰C. Summer is cool: the average temperatures in July range from + 7.5⁰ to + 10.5⁰. The number of days when the temperature is more than 5⁰C is 109-130. The annual precipitation ranges between 330 and 450 mm. The climate of the region is peculiar owing to two months of strong sunshine in summer (Yackovlev, 1961).

2.2. Vegetation

Coniferous forest dominates the vegetation in the region under investigation. The main species of trees are Pinus silvestris and Picea abies with some of Betula pubescens and Populus tremula. There are high bogs of sphagnum type, transitional mires of sedge fen type and cotton grass swamps in depressions (Payanskaya-Gvozdeva, 1990; Kats, 1971). Wild berry dwarf shrubs of Vaccinium vitis-idaea, Vaccinium myrtyllus, Empetrum hermaphroditum and Rubus chamaemorus are widely spread. Their fruits are edible and are widely consumed by the local population.

2.3. Soils

Forest soils of the region under investigation are of illivial humus-ferriferous podzol type that dominates the Kola peninsula. Its specific features are the developed forest litter (coarse humus organic layer) of 3-15 cm, rather shallow profile (30-60 cm) and clear differentiation of the soil layers. The soils are strongly acid, pH KC1 is 2.8-3.5 in the layer A0, hydrolytic acidity is 60-80 mg-equivalent/100 g, active aluminum is 5-8 mg-equivalent/100 g. The supply of coarse humus in the upper organic layer reaches 50-65% (Belov and Baranovskaya, 1969).

2.4. The source of BaP

The military aerodrome is situated 4 km from Monchegorsk. For the last 30 years the jet aircrafts have regularly taken off there. Main flight trajectories were situated over the area of the town. In addition, there are several stationary sources of BaP in Monchegorsk. These are coal and mazut boilers and smelting furnaces of the "Severonikel" smelter complex that use self-caking electrodes made of bitumen paste. The total emission of BaP by industrial sources of Monchegorsk is estimated at 50-60 kg per year (Reports, 1992-1998). The distance between "Severonikel" shops and the military aerodrome is about 6-7 km.

3. Materials and methods

3.1. Soil sampling

Soil samples were taken from the genetic horizon Ao - forest litter - by means of spade and knife advanced its entire depth from the surface to the mineral layer. Sample plots were made separately for every forest type within the urban territory (for example: town park, dispensary etc) and in the surroundings. Each total sample was prepared by mixing 5-7 taken from sites evenly distributed over the sample plot in the town area and three subsamples from the unpopulated territories. The samples were sorted manually: the roots, twigs and other external material were removed. After drying the samples at room temperature the content of PAH in the upper organic layer (A₀) has been carried out.

3.2. Berry sampling

Berry and soil samples were taken at the same forest localities but not at the same sample plots. Sampling was undertaken using a titanium scoop-comb (Rubus chamaemorus - by hands). The weight of each sample was about 300-500 g. The leaves and twigs were removed and samples dried at a temperature of 25-30⁰.

3.3. Procedure of PAH determination

PAH and BaP were extracted from the dried samples of soil and berries by hexan with the help of ultrasonic generator USDN-1. 2 ml of extract were frozen in an analytical cuvette at a temperature of liquid nitrogen (77 K) and afterwards they were irradiated by ultraviolet rays with wavelength 365 m. The spectrum of fluorescence of BaP has been recorded by spectrograph ISP-51 (Guide... 1989a, p.579).
The total error of BaP determination in the soils and berries did not exceed 20%. The limit of detection of BaP was 1 x 10 ppb.

Determination of the other PAH was also conducted by the method of high-performance liquid chromatography (HPLC). The obtained extract was concentrated by a factor of 10-15 by boiling down with a preliminary separation by the method of laminated chromatography on "Sillufol" plates or on an unfixed bed of aluminium oxide. 0.2 ml of extract was placed on the start line of the plate and it was treated by vapors of mixture of benzene and hexane. The zone containing PAH was identified by ultraviolet light and then it was washed by benzene. Benzene extract was concentrated by evaporation to the stage of wet salts and then it was dissolved by n-hexan and aceto-nitrite for the following analysis by the method of HPLC with direct phase column chromatography or with inversed phase CI8 (Alexeyeva and Teplitskaya, 1981; Guide... 1989b, p. 647).

4. Results

4.1. BaP in soils

The position of sample plots with their levels of accumulation of BaP in the layer A0 are shown in Table 1 and Fig. 1. BaP content in the soils remote from any industrial sources of pollution was found to be not more than the generally accepted background level 1-5 ppb. It has been estimated that soil belt located to the SW from the landing field of the airdrome was the most polluted one. The position of this soil belt correlates with the direction of the flight take off that was intensively used for the last 30 years. The concentration of BaP in the soils from the sample plots situated within 2 km between the end of the landing field and the shore of the lake was 100-200 ppb, i.e. 5-10 times more than the accepted threshold concentration and 20-40 times as large as the background content. Farther to the SW, BaP concentration in the soils taken from the sample plots situated in the locality including the communal refinery and the eastern and southern blocks of the town of Monchegorsk was 5-10 times more than the accepted threshold concentration. In the pine forest located to the NE from the city the content of BaP was about 128 ppb (6 times the accepted threshold concentration).

Table 1 Benz(a)pyrene content in soils of someplots in the town of Monchegorsk and in Monchegorsk region
No. in succession	Plot No	Distance and azimuth from the airdrome		Soil horizon and it's uepm cm	Concentration of BP
		km	degree	cm	ppb d.w.
1	253	0	0	AQP-3	89
2	252	1	220	Ajp-0-10 / AgP-10-20	100 / 17
3	251	2	220	AOp-10	197
4	302	3.2	220	A0P-6	45
5	301	3.5	215	A0p-5	36
6	304	4.5	220	AQP-8	15
7	307	5	205	AQ-AOP-6	24
8	310	9	210	A0p-5	31
9	255	3	163	A0-6	128
10	254	3	195	A0-10	58
11	281	8.7	175	Agp-8-16 / A^p-0-8	10 / 20
12	271	1	110	A0-3-5	12
13	272	3	100	A0-6-8	13
14	298	4.5	312	Indecomposed itter	4
15	287	7	258	AOP-10	4
16	290	10.5	280	AOP-7	1
17	317	14	230	Indecomposed litter	2
18	375	34	292	Ao-1-3	2
19	376	32	297	A0-3	3
20	377	34	300	A0-5	4

The position of the zones with maximum soil pollution coincides with the main trajectories of the jet aircrafts taking off. The belt of BaP dispersion is rather narrow and restricted by the fan of take off trajectories. The concentration of BaP in the soils of central, western and most part of the southern parts of the town were lower than the accepted threshold concentration, but 2-4 times larger than the background one. So, the soil content of BaP exceeds the background value by 2-20 times over almost the whole development land of Monchegorsk and also in the surrounding forest lots adjoining to the town from the south and north-east. BaP content did not exceed the background value in the soils in the impact zone of "Severonikel" complex, for example in 3-4 km to the SE from the facilities, but remote from the military aerodrome. BaP content also did not exceed the background level in the soils of the village near the aerodrome, that was situated near the chimneys of coal boilers but besides the landing field.
BaP is accumulated mainly by the upper thin layer of the soil litter. BaP content is sharply decreasing with depth. For example, BaP content is 100 ppb in the upper 10 cm layer of the soil and 17 ppb in the underlying layer, or 10 ppb of BaP in the upper 10 cm layer and 2 ppb in the underlying layer in the less contaminated locality.

The values of other PAH content in background samples are shown in Table 2. Small concentrations of anthracene, naphtalene, fluoranthene and diphenyl, i.e. of low-nuclear PAH, are found in the samples. The content of BaP in these samples was 1-3 ppb, i.e. it lies in the background limits.

Table 2 Content of PAH in A0 horizon of soils on background
Soil plot No.	Forest type	azimuth from the source degrees	C of PAH, mg/kg	Distance from the source, km
				benz(a)pyrene	anthracene	naphthalene	fluoranthene	diphenil
213	Birch forest V.myrtillus type	23	300	2.7	3	b.d.l.	b.d.l.	5
216	Spruce forest V.myrtillus type with birch	22	272	1.0	10	8	25	10
Concentrations of Phenanthrene, Pyrene, Fluorene and Benzoperylene in both the plots were below detection limit (b.d.l.)

4.2. BaP in berries

The position of the sample plots and their levels of BaP accumulation in berries are shown in Fig. 2 and in Table 3. It is found that the values of BaP concentrations in berries are within narrow limits 0.6-2 ppb, i.e. five-fold amplitude is observed. The high concentrations of BaP in berries 2-3 ppb was mentioned in the vicinity of the airdrome but the same values were found in the distant places without any industrial impact as well. Generally, the BaP content in berries exceeded accepted threshold concentration 1 ppb in 22 sample plots of 26 established ones.

The spatial distribution of BaP soil concentrations permits one to consider that the aerodrome near Monchegorsk really is the important source of environment pollution by this carcinogenic PAH. The development land of Monchegorsk and its nearest neighbourhoods have been intensively polluted by BaP over many years. Jet aircraft flights occurred regularly, but not every day and the process of the take off and flights took only a small part of the day. So it can be concluded that the extremely high accumulation of BaP in the soil has resulted from a rather small time of source influence upon the environment on one hand and that air concentration of BaP during flights is rapidly increasing on the other. The fact that the BaP content in the soil under the impact of "Severonikel" pollution is 10 times less than that along the trajectories of jet planes demonstrates that the smelter aggregates of "Severonikel" are a weaker source of BaP emissions into the environment in comparison with jets. The same can be noted about the coal and mazut boilers too.

Table 3 Benz(a)pyrene content in berries in Monchegorsk region
No. in succession	Plot No	Distance and azimuth from the airdrome		Berry species	Concentration of 3,4-BP ppb d.w.
		km	degree
1	253	0	0	V. vitis-idaea	2.6
2	252	1	220	V. vitis-idaea	2.8
3	251	2	220	V. vitis-idaea	1.2
4	254	3	197	V. vitis-idaea	1.0
5	254	3	195	V. vitis-idaea	0.6
6	307	5	205	V. vitis-idaea	2.6
7	317	14	230	V. vitis-idaea	2.0
8	282	29	190	V. vitis-idaea	0.8
9	396	42	195	V. vitis-idaea	1.4
10	398	42	195	V. vitis-idaea	1.2
11	45	42	205	V. vitis-idaea	1.5
12	47	44	217	V. vitis-idaea	2.0
13	49	42	227	V. vitis-idaea	1.5
14	114	60	242	V. vitis-idaea	1.4
15	271	1	110	V. vitis-idaea	3.0
16	317	14	230	Emp. hermaphr.	1.4
17		21	220	Emp. hermaphr.	0.6
18	282	29	190	Emp. hermaphr.	1.4
19		42	193	Emp. hermaphr.	0.6
20		41	195	Rubus hamaemorus	1.4
21		43	195	V. myrtillus	4.0

It is estimated that, in full accordance with published data (Shabad, 1973; Nickiforova et al., 1993; Gennadiev et al., 1997), accumulation of BaP takes place in the upper organic soil layer. Within this layer there exists a great gradient of accumulation - BaP content in the upper 8-10 cm is five times larger than that in the underlying 8-10 cm. It illustrates the slow migration of BaP down the soil profile of Kola podzol soils. Background content of BaP in the soils is found to be within the generally accepted values, i.e. 1-5 ppb. Concentration of BaP in the peat bog soil appeared to be twice as large as that in the forest litter of the neighbouring pine forest. Concentration of BaP in berries lay in the narrow range between 0.6 and 3 ppb and seemed independent of the BaP content in the soil. This fact suggests internal controls on the BaP formation in berries or dissipation of PAH in plants (Reilly et al., 1996). The mechanism of the process is still not clearly understood.

Over many years the territory under investigation has been intensively contaminated by the emissions from "Severonikel" that contain nickel, copper and sulfur dioxide (Barcan, 1993; Barcan and Sylina, 1996; Barcan and Kovnatsky, 1998). During this period emissions of nickel and copper accounted for about 3000-4000 tons per year and the value of S02 came to 220-240 thousand tons per year. It is known that compounds of nickel, for example NiS, are capable of provoking malignant neoplasms in cells under the influence of organic carcinogens of BaP type (Costa and Heck, 1986). It is also estimated that BaP can increase the accumulation and transport of nickel ions to oncogenic places of the cell (Costa and Heck, 1986). Besides, it is known that sulfur dioxide is the promoter of the carsinogenic activity of BaP (NAS, 1972).

Thus the investigated region is under the constant influence of three active chemical types of pollution. Two of them, viz nickel and BaP, are strong carcinogens and sinergists and the third one, S02, is harmful by itself and additionally plays the role of the promoter for BaP.

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