POLLUTION Impact of Contamination with Petroleum Products on Soil Properties
IVONA NIKOV A, BISER HRISTOV N Poushkarov Institute for Soil Science, Agrotechnolgy and Plant Protection, 7 Shosse Bankya Str., I 080 Sofia, Bulgaria E-mail:
[email protected] E-mail:
[email protected] Abstract. The paper deals with Vertisols and Cambisols contaminated by petroleum products and with high content of organic carbon in the surface horizons, which decreases in depth. In the profiles, small spots of organic origin are found. The biological activity in contaminated profiles is insignificant. The contamination with petroleum products has a slight impact on the soils' cation exchange capacity (CEC). Due to the higher values of the organic carbon in the surface horizon, the value of the CEC increases. Key words: soil petroleum contamination, organic carbon, cation exchange capacity.
um products is a huge catastrophe, including death and damage of the flora and fauna for a long period of time. It is established that the total annual contamination with these groducts is between 1.7x109 and 8.8x10 tons (Sing s a a s et al., 2000). It is detected mainly in areas with petroleum deposits, where extraction and transport are occurred. Petroleum processing companies are sources of permanent environment contamination with series of organic and nonorganic toxic compounds (Maximo vet al.; 1993, Markov, 2000). Each accident of pouring out the petroleum and its derivatives is a significant danger for the surrounding areas. This imposes fast assessment of the contamination degree and undertaking of remediation measures. The paper is aimed at establishing the impact of contamination with petroleum products on the physical and chemical properties of the soils near the fuel depot of Lukoil Bulgaria. MATERIAL AND METHOD
Increase of the petroleum extraction, processing and pipeline transportation, leakage due to transport accidents, bad storage conditions and manipulations cause a lot of ecological problems. One of the problems is the accommodation and migration of unspecific organic compounds in the soils, which fix nutrients (Markov, 2000), oxygen hunger appearance and total change in the biochemical processes (Ga id a r o v a et al., 1990). In the ecosystems, the strong contamination with petrole-
We investigate the areas around the Vetren and Iliantsu depots for allotment of petroleum products. Soil samples were taken from each depth of the representative profiles in the areas, as well as samples from the soil profiles near to the depots but not affected by carbon contamination. The analysis of soil samples are conducted using: soil morphological description; total carbon content; CEC, exchangeable cations, soil acidity. Studied profiles are as follows. Profile 1 is located at 570 m altitude in area of Iliantsi depot, Sofia, with coordinates N 42'7625 E 23'3260. The relief is flat. Soil parent materials are
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INTRODUCTION
Pliocene and Quaternary alluvial materials. The vegetation is Chrysopogon gryllus, scilla (Scilla bifolia), dandelion (Tarataxum ojficinale), etc. Anthropogenic impact is contamination with petroleum products. Profile 2 (Marker) is located at 570 m altitude around 400 m from the Iliantsi depot, with coordinates N 42'46 08 3'21 03. The relief is flat. Soil parent materials are Pliocene and Quartemary alluvial materials. The vegetation includes cultivated plants. Profile 3 is located at 776 m altitude, in area of Vetren depot with coordinates N 42' 15 59 E 24'03 36. The relief is hilly-plain. Soil parent materials are schist and gneisses. The vegetation is grassy Chrysopogon gryllus. Anthropogenic impact is contamination with petroleum products. Profile 4 (Marker) is located at 776 m altitude, near by the depot of Vetren with coordinates N 42'15 54 E 24'03 39. The relief is hilly-plain. Soil parent materials are schist and gneisses. The vegetation is grassy and frutescent: dog rose (Rosa canina ), Chrysopogon gryllus, etc. RES ULTS AND DISCUSSIONS Morphological description of the contaminated profiles is as follows. Profile 1. Iliantsi, Endocalcic Vertisols • Ach) 0-24 - Dark (lOYR 3/1), wet, solid, slightly clayey, middle lumpy to crumby structure, fine roots, impurities of gravel, coarse stones, sediments on the surface horizon, slight bilogical activity, non-calcareous, gradual transition. • A2 24-51 - Dark brown (lOYR 4/2), wet, solid, slight clayey, middle lumpy to crumby structure, gleyic spots, no roots, black spots on the surface horizon, non- calcareous, gradual transition. 428
• AB 51-95 - Dark (lOYR 3/1), wet, highly compact, slight clayey, high lumpy structure, coarse lumpy structure, construction waste, slightly calcareous, smo-oth transition. • BCK 95-142 - Dark brown (lOYR 4/3), humid, compact, slight clayey, coarse lumpy structure, small carbonate concretions, black spots occurred, calcareous, clear boundary. • CK 142-200 - Brown (lOYR 4/4), humid, compact, slightly clayey, lumpy structure, carbonate concretions, black spots occurred, calcareous. Profile 3. Vetren, Haplic Cambisol • A("I) 0-21 - Dark (lOYR 3/3), humid, solid, clay-gritstone, crumby to lumpy structure, black sand from cleaning process, shingles, black sediments, roots, small biological activity non-calcareous, noticeable transition. • AC 21-30 - Brown (lOYR 4/3), humid, crumbly, clay-gritstone, crumby to lumpy structure, fine roots, noncalcareous, gradual transition. • Cl 30-52 - Grey-reddish (2,5YR 6/2), humid, crumbly, clay-gritstone, no structure, construction materials wastes, non-calcareous. Iliantsi depot soil contaminated with hydrocarbons was analyzed in previous studies (Table 1). It is observed that oil content is ten times higher compared to clear control profile, but only at a depth of 20 cm. There are no significant differences in the depth of 20-50cm and 50-80 cm. The contaminated soils with petroleum products from Iliantsi and V etren are located next to petroleum reservoirs or other areas, where the soils are additionally affected by anthropogenic activities mainly due to construction. This is observed in the morphological description of the profiles, where impurities of gravel, fine black sand, construction waste and other inclusions with anthropogenic character are foScientific Research Papers: Pollution
Table 1. Hydrocarbons content in three bathyal soil samples from contaminated and marker profiles in the area of petroleum denot Iliantsi (I 1 i e v et al. 2011) Hydrocarbons ( % ). Soil horizon depth Contaminated soil (cm) Marker 4.5 OA 0-20 0.12 0.13 20-50 0.07 0.023 50-80
und. In the two profiles, traces from petroleum products contamination are also found mainly as sediments on the surface horizon. It is mentioned also in the morphological description of the soils and due to a fire hazard, test for purification or removal of petroleum products should be made. The reason for that could be the presence of fine black quartz sand on the surface, which is used for cleaning of metal surfaces. The biological activity in both profiles is small, any finds of earth-worm or other small species are missing. Minimum grass vegetation and fine roots in the surface horizon are detected. The profile in Iliantsi area is deeper. It is composed of Vertisols and organic formations as small black spots are found along the entire profile. These spots occurred as a result of often soil contamination. There are black sediments in the surface horizon of both profiles as a result of old floods. In depth, such sediments are not found. While soil samples were taken from contaminated soils (Profile 1 and 3), a great amount of water (puddles) was detected. The mentioned about is typical only for areas with significant petroleum floods. The decrease of water permeability of soils contaminated with petroleum products and other organic pollutants is known as soil hydrophobicity (water-repellent property of the soil). Therefore, the contamination with petroleum products impacts also the physical properties of soils, especially the water permeability.
The high values of total carbon in the surface horizons of both profiles also determine the amount of sediments from the surface contamination. In Profile 1, petroleum depot of Iliantsi, the carbon content is over 6 %, which is two times more than in the marker (Table 2). This regularity is found and for the area of Petroleum depot of Vetren where, in the humus poor Shallow Cinnamon Forest soils, the content of organic carbon in contaminated areas reaches 2.47 % in the surface horizon. It is obvious that the petroleum products are accumulated in the surface horizon, since in both profiles the contents of deep samples are close to the values for the markers. In the humus accumulative horizons of the contaminated soils, the total content of organic carbon includes the humus content and petroleum products residues. The chemical reaction (pH) of contaminated soil profiles is higher than pH of the markers with 1 unit. It should be mentioned that this is not due to the contamination with petroleum products, since they are mainly with organic origin and contain some organic acids. Thus, a light acidification of the soils even should be expected. The higher pH is a result of the great amount of construction waste, which is described above in the morphological description of the soils, never the less that, in Profile 1 in depth, the carbonates are with natural origin. The high content of calcium from the construction activities has also
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Table 2. Total carbon, soil reaction (pH), sorotion capacity of studied soils CEC CEC Exchangeable elements Total CEC Strongly Slightly Horizon depth Mg H Al+H Ca c pH acid acid (cm) (%) (meqv I 100 g soil) Profile 1, Iliantsi
A 0- 5(surface radial) AchJ 0 - 24 A2 24- 51 AB 51-95 BC. 95 -142 c. 142-200
2.12
7.2
47.6
47.2
0.4
1.42
0
40.3
6.2
6.20 1.2 0.16
7.2 7.4 7.6 7.9 7.6
45.5 44.7 45.1 49 49
44.5
1.2
-
-
0.9 0.7 0.9 0.0 0.0
0 0 0 0 0
36.2 37.5 36.0 40.8 41.0
8.5 6.5 8.2 8.2 8.0
-
-
Profile 2. lliantsi (Marker)
0-5 5- 20 20-40 40- 80
0.85 0.8 0.5 0.4
6.00 6.15 6.30 6.60
43.5 43.6 40.1 43.7
37.2 37.6 34.7 38.8
6.3 6.0 5.4 4.9
4.5 4.2 3.6 3.3
0 0 0 0
32.4 32.5 29.1 33.9
6.7 7.0 6.9 6.7
2.3 1.5 1.0
0.1 0 0
10.5 11.9 12.0
3.6 4.1 4.2
0.8 0.4
6.7 7.4
3.0 1.8
Profile 3. Vetren
Achl 0- 21 AC 21 - 30 c 30 - 52
2.47 0.83 0.72
5.9 6.15 6.6
16.5 18.0 17.8
14.2 15.6 15.8
2.3 2.4 2.0
Profile 4. Vetren (Marker)
Achl 0 - 20 C/R20-40
0.86 0.85
4.75 5.15
14.2 12.4
impact on the physical and chemical properties of soils, as the amount of the exchangeable calcium increases. The contamination with petroleum products has comparatively slight impact on the sorption capacity of the soils. There is slight increase of the total sorption capacity of the humus accumulative horizons mainly due to higher content of total carbon. Comparison could be made with the rich humus soils in which the amount of humus increases the sorption capacity. Vertisols in Iliantsi 430
12.0 10.2
2.2 2.2
3.6 2.6
area have rather higher sorption capacity than the Cinnamon Forest soils, since the the clay content is very high and they are also composed of old clayey Pliocene and Quaternary formations. Interesting fact is that, in horizon Ck of Profile 1, highest sorption capacity is detected. Probably, a significant impact on the horizon has the clayey bedrocks. There are no considerable differences in the amount of exchangeable hydrogen and aluminum in noncontaminated soil profiles. Scientific Research Papers: Pollution
CONCLUSION In the surface horizon of soils contaminated with petroleum products, a high content of organic carbon is found. Its content decreases in depth. In the soil profile small spots with organic origin are found. The petroleum products in surface horizon impede the ground water flowing. The biological activity in contaminated profiles is insignificant. The contamination with petroleum products has a small impact on the cation exchange capacity of the soils. Due to the higher values of organic carbon, mainly in the surface horizon, the va~ue of the cation exchange capacity mcreases. Acknowledgements. We would like to thank National Science Fund, Ministry of Education, Youth and Science of Bulgaria, for the financial support of Project DMU - 02/2 (2010) and Lukoil Bulgaria for kindly assistance during the field experiments. REFERENCES G a yd a r ova, S., M. Roy a chi, 1990. Danube Water Quality Used for Irrigation. - In: Proceedings of Quality Protection Danube Symposium, 19-20 October 1990. I l i e v I., G. G ache v a, I. N i -
kova, D. Nedelcheva. 2011. Algal Diversity of Oil Polluted Vertisol. - Youth Scientific Conference Dedicated to Kliment's Days, Bulgarian First Edition, Second Book, ISSN 1314-4960, 84-88. Maximo v, G., S. S a f on n i k o v a. 1993. Risk of Contamination of Agricultural Emissions from Petrochemical Complexes, Pollution Circle. Environment. - Problems of Toxicology and Epidemol. Abstracts of Theses, Intl. Conf., Moscow, 80-81. Markov, E. 2000. Scientific Experiment to Quantify the Level of Soil Contamination by Petroleum Products by Analyzing the Amount of Organic Carbon. - Soil Science, Agrochemistry and Ecology, 3, Sofia, 9-13. Markov, E. 2000. Changes in Some Basic Properties of Soils Contaminated with Petroleum Products. Ph.D., Poushkarov Institute for Soil Science, Agrotechnolgy and Plant Protection, Sofia, p. 148. Singsaas, I., M. Reed, P. Dalin g. 2000. Experiences in Dispersant Treatment of Experimental Oil Spills. - Proceedings of the SPE Int. Conf. on Health, Safety and the Environment in Oil and Gas Exploration and Production, Stavanger, Norway, Paper 61117, 26-28, June, 2000.
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