Danube - River of Cooperation

 

Evaluation of Soil Pollution at the Oil Refinery Site

by Biljana Škrbić, Nataša Ðurišić-Mladenović and Jelena Cvejanov [1]

paper presented at the XI International Conference "Danube - River of Cooperation", November, 17-19 2000

 

Introduction

The Oil Refinery of Novi Sad is the unique refinery within the Petroleum Industry of Serbia, which produces motor and industrial fuels, motor and industrial lubricating oils, and road and industrial bitumens. The Refinery is located on the bank of canal Danube-Tisa-Danube that is directly connected with the Danube River and is located not more than 1.5 km from downtown Novi Sad. It is built on gravely sandy slit deposits with a thickness of up to 8 m. The groundwater table is located only 1-2 m below ground level of the Refinery. The overall groundwater flow is moving in the southeastern direction. There is no protective barrier at the downstream end of the refinery to prevent contaminated groundwater from leaving the refinery site.

The water supply of Novi Sad is based on the groundwater from the aquifers in the coastal area of the Danube River. The groundwater is mainly abstracted through some infiltration galleries, located in the immediate vicinity of Danube at the Ratno Ostrvo site on the northern bank. These galleries are located some hundred meters downstream of the Refinery and the quality of the abstracted groundwater is closely linked to that of the Danube River, since about 80-90% of the infiltrated water originates from the river. On the other hand the quality of the groundwater is also linked with effect from the refinery facilities and also from potential contaminators located in the vicinity.

During the period of NATO aggression (March 24 to June 9, 1999) the Oil Refinery of Novi Sad was twelve times bombed. Many of the storage tanks at the oil refinery were directly hit and caught fire or indirectly hit by debris. Some of the indirectly hit tanks also caught fire while others leaked. 348,700 m3 of storage tanks with more than 100,000 t of crude oil and its products were destroyed. It was estimated that about 90% of these were burned, 10% leached and 130 t recovered. Approximately 15% (3000 m) of the pipe system both overground and underground were reported seriously damaged. There is still considerable leakage from these damaged pipes. During the fires various substances with carcinogenic, mutagenic, toxic and perilous effects to human, plants and animal life were released into the air. The Danube River and the riverbanks downstream of the refinery were heavily contaminated right after the conflict, due to outflow of crude oil and oil products from the refinery. Also, the impact of the deposition of particles released during the fires into the air cannot be disregarded, as the ones were carriers of many toxic products of combustion. In the postconflict period terrestrial run-off of rainwater which leaches pollutants from soil contributes to their further accumulation in the groundwater, as well as in the river water and the sediments. Also, on-going industrial and traffic activities contribute to the additional pollutant burden in the Danube River.

Soil pollution at the refinery site is the result of both the spillage of enormous quantities of oil and its refined products and the deposition (dry and wet) of the carbonaceous particles from the air released during the fires. The instantaneous quantities of the total polycyclic aromatic hydrocarbons in the air of the town and its vicinity ranged from 1-431,000 ng/m3 (Škrbić, 1999). The presence of benzo(a)pyrene in the ambient air is not allowed according to Republic of Serbia legal provisions (Republic Ministry of Environment, 1999). Polycyclic aromatic hydrocarbons (PAHs) are 10th on the 1999 CERCLA list, while benzo(a)pyrene is 8th on this one as the most carcinogenic. The background concentration of benzo(a)pyrene for Eastern Europe is 0.01-0.61 ng/m3 (Rovinski, 1992). The determined concentrations of the total organic matter in precipitation samples downwind of Novi Sad collected in two sampling period during the fires, from three (May 3-6) to five (May 6-10) days, were ranged from 0.28-0.52 mg/L. The quantity of benzo(a)pyrene in integrated sample obtained by mixing all the collected precipitation samples was 0.03 mg/L (UNEP/UNCHS, 1999a). Levsen et al. (1993) cited scarce literature data for the concentration of PAHs in rain water that was ranged from 0.06-0.99 mg/L. Leister and Baker (1994) determined the mean total rain concentration of 14 PAHs and benzo(a)pyrene in rural site that is not impacted by anthropogenic emission sources, of 59 ng/L and 1.9 ng/L, respectively.

To determine the concentration of residues in the post conflict period two types of soil samples were taken from several fields of the Refinery: (a) surface zone, and (b) soil core samples, in an effort to quantify the deposition and migration of polycyclic aromatic hydrocarbons and polychlorinated biphenyls (PCB). The sampling sites and the analytes whose presence in the definite sample needed to be determined were chosen on the base of the damage level by the experts of UNEP/BTF Industrial Sites Mission conducted in July 1999.

 

Experimental Procedure

The surface and core soil samples were taken with a garden trowel and a hand-held coring device, respectively, from several sites of the Refinery, depending on the position of the destroyed plant units. The position and description of field sites in the Oil Refinery, from which the soil samples were taken, is presented in Figure 1. The samples coded NS, X2 and X3 were stored frozen in dark jars until analysis. Analytical methods for PAHs and PCBs are basically three-step procedures: a) extraction of organic matter from the sample matrix, b) isolation of PAHs and PCBs from the extract, c) identification and quantitative determination.

10 g of each sample was extracted in a Soxhlet apparatus with solvent mixture (acetone-hexane) for 18 h at a rate of 8 cycles/h (Lee et al., 1987). After that, dry extract was evaporated down to ca. 5 mL using a rotary evaporator with a 35oC water bath. The extract was separated by adsorption chromatography on silica gel with hexane and dichloromethane-hexane into two fractions containing PCBs and aromatic hydrocarbons, respectively. The first fraction with PCBs was evaporated until ca. 10 mL. The second fraction containing PAHs was reduced to a ca. 5 mL using a rotary evaporator. After the addition of hexane and isooctane, the evaporation was repeated until 3 mL. This concentrate was transferred to alumina column, and first hexane eluate was discarded, as this fraction contained the aliphatic hydrocarbons. The PAHs were removed from the column by elution with toluene until a volume of 10 mL was collected.

  1. NS S1 0-30 and NS S1 80-100 - damaged storage tanks with leaded motor gasoline and destroyed pipeline
  2. NS S1 0-10 - about 10 m opposite of the first one
  3. NS S4 0-10 - reservoir of bitumen, just opposite of the additive storage
  4. NS S4B 0-10 - in the very close vicinity of vacuum oil distillate
  5. X2 0-20, X2 20-50 and X2 50-100 - in the vicinity of three totally destroyed crude oil storages with the capacity of 10,000 t each
  6. X3 0-10, X3 10-45 and X3 45-55 - about 10 m distance from the taken sample signed X2
Fig. 1. Position of Oil Refinery in Novi Sad and locations from which soil samples for pollutant analysis were taken

The recovery was estimated by spiking solutions containing five PAH (phenanthrene, anthracene, benzo(a)anthracene, chrysene, benzo(a)pyrene) and three PCB (hexachlorocyclohexane (a+b+g), Aroclor 1260 and 2,3,4,5,6-pentachlorobiphenyl). Standard solutions were injected into clean soil sample before extraction. Recovery studies were performed using spiked samples by the procedure described above. The mean recovery for the method was 90%.

PAHs in the extracts were identified by retention time comparison of standard mixture of 16 individual hydrocarbons according to the EPA list. The total amount of PAHs is the sum of these individual hydrocarbons. Identification of PCB was done by standard mixture as well. Polycyclic aromatic hydrocarbons and polychlorinated biphenyls were determined by gas chromatography using flame ionization (FID) and an electron capture (ECD) detector, respectively. Identification of individual polycyclic aromatic hydrocarbons was obtained by GC/MS. The following working conditions were used for determination of:

  • polychlorinated biphenyls:
    GC/ECD, DANI Microcolumn Expander
    column: BPX5, 30 m x 0.32 mm, 1mm
    temperature program: 50oC, 1 min, 7 oC/min, 290oC, 5 min
    injector temperature: 220 oC
    detector temperature: 220 oC
    injected volume: 1mL
    carrier gas: nitrogen
    split ratio: 1:10
  • polycyclic aromatic hydrocarbons:
    GC HP5890 with mass selective detector HP5971A
    column: ULTRA 2, 25 m x 0.2 mm, 0.33 mm
    temperature program: 50 oC, 2 min, 25 oC/min, 160 oC, 1 min, 5 oC/min, 300oC, 0 min, 25 oC/min, 325oC, 5 min
    injector temperature: 250 oC
    detector temperature: 280 oC
    injected volume: 1mL
    carrier gas: helium
    split ratio: 1:100

    GC/FID, SP-7100
    column: SPBTM- 5, 30 m x 0.25 mm, 1 mm
    temperature program: 60 oC, 2 min, 10 oC/min, 120 oC, 1 min, 15 oC/min, 290 oC, 50 min
    injector temperature: 280 oC
    detector temperature: 330 oC
    injected volume: 1mL
    carrier gas: nitrogen
    splitless mode 1 min

 

Results and Descussions

A total of eleven soil samples from field sites of the Refinery after the operation "Allied Force" were analyzed. Soil sample content of total polycyclic aromatic hydrocarbons and benzo(a)pyrene (B(a)P) as the most carcinogenic one, and polychlorinated biphenyls in mg/g dry matter is presented in the Table 1. Content of these compounds is given as a function of the depth.

The lowest concentration of polycyclic aromatic hydrocarbons indicated that these ones had not migrated to the depth more than 60 cm at the sites where crude oil was spilled out and burned.

Table 1. Soil samples content of PAH and PCB in mg/g dry matter as a function of depth
Location Depth, cm PAH B(a)P PCB
NS S1a 0-30 29.18 3.07 nm (h)
80-100 0.75 0.03 nm
NS S1b 0-10 30.67 1.85 0.76
NS S4 c 0-10 59.13 3.35 0.24
NS S4B d 0-10 86.19 4.33 nm
X2 e 0-20 39.9 7.19 nm
20-50 31.8 2.82 nm
50-100 bdl (g) bdl nm
X3 f 0-10 42.15 8.12 nm
10-45 29.19 3.02 nm
45-55 30.50 2.09 nm
average content (i) 0-30 47.87 4.65 0.50
(g) - bdl = below detection limits; (h) - nm = not measured; (i) - includes only surface soil samples at all locations

UNEP/BTF Industrial Sites Mission conducted in July 1999, confirmed significant level of soil contamination with hydrocarbons, particularly in the northeastern part of the plant. At different locations total petroleum hydrocarbons concentrations were up to 11000 mg/kg, especially from groundwater level down to 0.5 m. The results of the field investigation carried out by Novi Sad Waterworks after the BTF Industrial Site Mission, indicated hydrocarbon concentrations up to 42325 mg/kg (UNEP/BTF, 2000). Supprisingly, according to the results of BTF Industrial Site Mission (UNEP/UNCHS, 1999a), presence of PAHs is not so high as it can be expected for industrial area subjected to anthropogenic impacts. At two locations where the presence of the ones is identified, NS S1 0-30 cm and NS S4 0-10 cm, obtained PAH concentrations were 13 and 1.7 mg/g, respectively. The analytical procedure used for this investigation was not described, so those results could not be used without precaution. Additional investigations during the UNEP/BTF Feasibility study in February 2000 showed significant groundwater contamination by PAHs and other oil components. For example, the concentration of naphthalene as the most water soluble and mobile PAH in various sample points outside the refinery was up to 4.1 mg/l (UNEP/BTF, 2000). According to Oosterban and Jamet (1998), who investigated the pollution of the groundwater at the former gaswork and coking plants sites, PAH contamination is primary composed of naphthalene, i.e. naphthalene was presented about 50% of the total PAH concentration in the groundwater samples. The reference concentration in groundwater for the light three-ring PAHs, phenanthrene and anthracene, according to the European Community (Netherlands), is 0.100 mg/l (Kubinec et al., 1993).

 

Conclusion

The Oil Refinery is located on a layer of gravely sandy slit deposits (high permeability and vulnerability) with the groundwater table at shallow depth (1-2 m below ground level), the contamination with polychlorinated biphenyls and polycyclic aromatic hydrocarbons indicates a great environmental risk. Because of high groundwater, migration of these pollutants takes place to the river Danube, and their presence in sediment is evident (UNEP/UNCHS, 1999b). The measured concentration of PAHs in soil samples taken from bombing industrial site of the Oil Refinery Novi Sad indicated that they migrated to the depth of 60 cm at the places where crude oil spilled and burned. Highly contaminated soil will act as a permanent source of contamination for the groundwater, that flows from the oil refinery site to the surroundings, including the canal southern of the refinery as well as the Danube River. This will have an adverse effect on the aquatic environment and a very likely long-term effect on the infiltration galleries. Therefore, this location of the Oil Refinery of Novi Sad should be treated for removal of identified pollutants due to protecting the health of 350,000 inhabitants of Novi Sad.

 

References

CERCLA Priority list of hazardous substances that will be the subject of toxicological profiles & support document, (1999). Division of Toxicology, Agency for Toxic Substances and Disease Registry, US Department of Health and Human Services in Cooperation with the US Environmental Protection Agency; http://www.atsdr.cdc.gov.

Kubinec, R., Kuran, P., Ostrovsky, I. and Sojak, L. (1993). Determination of polycyclic aromatic hydrocarbons from bitumen concrete roads in drainage water by microextraction, large-volume sampling and gas chromatography-mass spectrometry with selected ion monitoring. J.Chromatogr., 653, 363-368.

Lee, H.B, Dookhran, G. and Chau, A.S.Y. (1987). Analytical reference materials, Part VI. Development and certification of a sediment reference material for selected polynuclear aromatic hydrocarbons. Analyst, 112, 31-35.

Leister, D. and Baker, J. (1994). Atmospheric deposition of organic contaminants to the Chesapeake Bay. AtmosphericEnvironment, 28, 1499-1520.

Levsen, K., Behnert, S., Priess, B., Svoboda, M., Winkler, H. and Zietlow, J. (1990). Organic compounds in cloud and rain water. Chemosphere, 21, 1037-1061.

Oosterbaan, J. and Jamet, P. (1998). Characterization of PAH on former gaswork and coking plants by exploratory statistics, Proceeding of papers of 4th International Symposium and Exhibition on Environment in Central and Eastern Europe (CD), #313, Warsaw.

Republic Ministry of Environment, (1999). Provision of changes and additions of the provision of limit concentrations methods for determination of imission criterion for measuring location and acquisition of data. Republic of Serbia legal provision. No. 30, 495.

Rovinsky, F.Ya. (1992). Monitoring background atmospheric pollution in Central and Eastern Europe. in Coping with crisis in Eastern Europe's environment. Parthenon Publishing group, Carnforth, England, Ch.5, 69-86.

Škrbić, B.D. Appendix A in Vukmirović Z.B. (1999). Release of hazardous, toxic and cancerogenic substances into the atmospheres during the warfare in Yugoslavia and an assessment of their environmental impact, Book of abstracts, 2nd International Conference of Balkan Environmental Association (B.E.N.A.), Industrial pollution, Sofia, Bulgaria.

UNEP/UNCHS Balkans Task Force Report (1999a). Novi Sad site (www.grid.unep.ch/btf).

UNEP/UNCHS Report (1999b). The Kosovo conflict. Consequences for the environment & human settlements. Geneva.

UNEP/BTF Feasibility Study (2000). Novi Sad-Report and project proposals.

UNEP/BTF Feasibility Study (2000). Novi Sad-Report and project proposals.

[1] Faculty of Technology, University of Novi Sad
    Address: Bulevar cara Lazara 1, 21000 Novi Sad, SCG

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