Directory UMM :Data Elmu:jurnal:O:Organic Geochemistry:Vol31.Issue12.Dec2000:
Organic Geochemistry 31 (2000) 1733±1741
www.elsevier.nl/locate/orggeochem
Weathering of fuel oil spill on the east Mediterranean coast,
Ashdod, Israel
Shai Ezra a,*, Shimon Feinstein a, Ithamar Pelly a, Dan Bauman b,
Irena Miloslavsky c
a
Department of Geological and Environmental Sciences, Ben-Gurion University of the Negev, Beer Sheva, 84105, Israel
Department of Geography and Environmental Development, Ben-Gurion University of the Negev, Beer Sheva, 84105, Israel
c
Department of Organic Chemistry and Casali Institute, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
b
Abstract
Residual fuel oil spilled into the sea from the Eshkol power station on 8 February, 1998 contaminated about 9 km of
the foreshore north of the Ashdod harbour. A study of the aliphatic, polycyclic alkane and polyaromatic hydrocarbon
(PAH) composition of the spilled oil shows rapid weathering in the early stages followed by gradual slowdown after
about three months. Weathering of isoprenoids and PAH compounds and variation in Pr/Ph ratio appear to occur
almost contemporaneously with that of n-alkanes, at a relatively moderate level of degradation, when much of the
>C20 n-alkane envelope is still well preserved. Depletion of various compounds in accordance with molecular size
rather than molecular structure appears to imply that physical weathering processes, i.e. evaporation and perhaps
¯ushing due to wave energy, might have played an important role in the degradation of the spilled residual fuel oil in
this study case. # 2000 Elsevier Science Ltd. All rights reserved.
Keywords: Fuel oil spill; Pollution; Weathering; Hydrocarbons; East Mediterranean foreshore
1. Introduction
Extensive transportation of petroleum by ocean going
tankers, oil exploration and production activities, and
the frequent location of oil consuming industries in
coastal areas make marine and coastal environments
particularly vulnerable to pollution by petroleum and its
breakdown products. Oil spilled into the environment is
subjected to a variety of weathering processes, including
evaporation, dissolution, dispersion, photochemical
oxidation, ¯ushing due to wave energy, emulsi®cation,
microbial biodegradation and adsorption to suspended
matter and deposition on to the sea¯oor (Bohem et al.,
1982; Wang et al., 1997b; Garret et al., 1998). Weathering processes involved, together with the chemical
nature of the spilled oil, determine the fate and rate of
degradation. The weathering processes under natural
conditions are complicated and depend on a variety of
* Corresponding author. Fax:+972-7-6472997.
E-mail address: [email protected] (S. Ezra).
factors. Therefore, studies of weathering under natural
conditions are essential for the understanding of these
processes in the natural environment. Each weathering
process may have a dierent eect on the oil components (e.g. Connan et al., 1980; Boehm et al., 1982;
Volkman et al., 1984; Rowland et al., 1986; Wang and
Fingas, 1995a,b; Fisher et al., 1996; Budzinski et al.,
1998; Sauer et al., 1998; Garrett et al., 1998). Thus,
variation over time in the composition of dierent oil
constituents can be used to monitor the extent of
weathering. A detailed understanding of weathering
processes that oil is subjected to is required in order to
reduce environmental damage and develop eective
protection strategies.
On 8 February, 1998 residual fuel oil from the Eshkol
power station, north of Ashdod harbour, spilled as a
result of a technical failure. The fuel spilled into the sea
through the cooling water outlet system and formed an
elongated ¯oating lens in the nearshore that was transported by the waves. It also landed on the beach and
polluted a 9 km stretch of the coastline. The coastline
polluted by the spill is generally characterized by sandy
0146-6380/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved.
PII: S0146-6380(00)00091-7
1734
S. Ezra et al. / Organic Geochemistry 31 (2000) 1733±1741
beaches with scattered beach rock boulders, partially
exposed due to sand mining in the 1950s. The spill provided an excellent opportunity to monitor, with relatively
high resolution, the variation in the chemical composition of the spilled residual oil over time and characterize
the weathering processes in the Israeli coastline of the
east Mediterranean under natural conditions. Systematic sampling at the polluted shore started about 48 h
after the spillage began, at a time when the beaching of
tar was still occurring. Moreover, knowledge of the
source fuel provided a reference composition and the
possibility to extend the control on the weathering processes back in time to their initiation (`zero time').
2. Experimental
2.1. Samples
Systematic sampling of the polluted shore stretch
commenced 48 h after the spill began and continued for
more than a year. The residual oil pollution (tar patches) was sampled at three stations (Fig. 1), each comprising several sampling points of sand and beach rocks.
Sand sampling points lasted for only about one month,
before they were washed away. Contamination patches
on rocks were persistent throughout the study period and
were sampled continually for 14 months. Sampling was
carried out at 2 weekly intervals during the ®rst 4 months
and subsequently once a month, on the basis of the initial
results. A sample of the initial residual fuel oil was
obtained from the Eshkol power station fuel container.
Samples were stored in sealed vials and kept at 5 C.
2.2. Extraction and liquid chromatography
The samples were solvent extracted with toluene.
Asphaltenes were precipitated from the extracted fraction with n-hexane (50:1 hexane:toluene). The deasphalted extracts were fractionated using column
chromatography (30 cm length and 1 cm width column
®lled half with activated alumina and half with activated
silica gel). Approximately 100 mg of deasphaltened
fraction was adsorbed on to the top of the column. The
aliphatic fraction was recovered by eluting with hexane
(300 ml), the aromatic fraction with toluene (300 ml)
and the resins with methanol (200 ml).
2.3. Gas chromatography (GC)
Aliphatic fractions were analyzed on a Hewlett Packard (HP) 5890 FID gas chromatograph with a HP-5
fused silica column (30 m, 0.32 mm i.d., 0.25 mm ®lm).
The injector and the detector were held at 300 C and the
column temperature program was 50 C (2 min), followed by heating to 300 C at 4 C/min (isothermal hold
for 20 min). The carrier gas used was He.
2.4. Gas chromatography±mass spectrometry (GC±MS)
Fig. 1. Location of polluted coast and sampling sites. AN, AC
and AS represent, respectively, the northern, central and
southern sampling stations.
Aliphatic and aromatic fractions of selected samples
were analyzed by GC±MS. Scanning of polycyclic
alkanes was performed using a HP 57904A GC directly
connected to a ZAB- II F (VG analytical) double-focusing MS. The GC was equipped with a DB-5 fused silica
column (30 m, 0.32 mm i.d., 0.25 mm ®lm). The injector
and the detector were held at 300 C. The MS operated in
selected ion resolution (SIR) mode. The ions monitored
were m/z 191.1800 for hopanes and m/z 217.1956 and
218.2035 for steranes. To obtain spectral data and identi®cation of the PAH compounds a HP 5890 GC directly
connected to an HP 5971A MS was used. The GC was
equipped with a HP-1 fused silica column (30 m, 0.20 mm
i.d., 0.33 mm ®lm). The injector and the detector were
held at 280 and 250 C, respectively. The MS operated in
a single ion monitoring (SIM) mode. The ions monitored
were m/z 128, 142 and 156 for naphthalene and alkylnaphthalenes; m/z 178, 192 and 206 for phenanthrene
and alkylphenanthrenes; m/z 184, 198 and 212 for
dibenzothiophene and alkyldibenzothiophenes; and m/z
166, 180 and 194 for ¯uorene and alkyl¯uorenes. The
column temperature program for both GC±MS instru-
S. Ezra et al. / Organic Geochemistry 31 (2000) 1733±1741
ments was at 50 C (2 min), followed by heating to
300 C at a 4 C/min rate (isothermal hold 20 min).
3. Results
3.1. Aliphatics
Fig. 2a±c shows C15+ gas chromatograms obtained
for the n- and isoalkanes in the residual fuel oil sampled
from the power station container and two tar samples
(station AC) obtained at 3 and 30 weeks after the spill.
The n-alkane envelope in the residual fuel oil (Mazut)
from the power station container is characterized by nalkanes ranging from C13 to C35 maximizing at n-C22
(Fig. 2a). Subsequently, there is an absence of aliphatic
compounds
www.elsevier.nl/locate/orggeochem
Weathering of fuel oil spill on the east Mediterranean coast,
Ashdod, Israel
Shai Ezra a,*, Shimon Feinstein a, Ithamar Pelly a, Dan Bauman b,
Irena Miloslavsky c
a
Department of Geological and Environmental Sciences, Ben-Gurion University of the Negev, Beer Sheva, 84105, Israel
Department of Geography and Environmental Development, Ben-Gurion University of the Negev, Beer Sheva, 84105, Israel
c
Department of Organic Chemistry and Casali Institute, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
b
Abstract
Residual fuel oil spilled into the sea from the Eshkol power station on 8 February, 1998 contaminated about 9 km of
the foreshore north of the Ashdod harbour. A study of the aliphatic, polycyclic alkane and polyaromatic hydrocarbon
(PAH) composition of the spilled oil shows rapid weathering in the early stages followed by gradual slowdown after
about three months. Weathering of isoprenoids and PAH compounds and variation in Pr/Ph ratio appear to occur
almost contemporaneously with that of n-alkanes, at a relatively moderate level of degradation, when much of the
>C20 n-alkane envelope is still well preserved. Depletion of various compounds in accordance with molecular size
rather than molecular structure appears to imply that physical weathering processes, i.e. evaporation and perhaps
¯ushing due to wave energy, might have played an important role in the degradation of the spilled residual fuel oil in
this study case. # 2000 Elsevier Science Ltd. All rights reserved.
Keywords: Fuel oil spill; Pollution; Weathering; Hydrocarbons; East Mediterranean foreshore
1. Introduction
Extensive transportation of petroleum by ocean going
tankers, oil exploration and production activities, and
the frequent location of oil consuming industries in
coastal areas make marine and coastal environments
particularly vulnerable to pollution by petroleum and its
breakdown products. Oil spilled into the environment is
subjected to a variety of weathering processes, including
evaporation, dissolution, dispersion, photochemical
oxidation, ¯ushing due to wave energy, emulsi®cation,
microbial biodegradation and adsorption to suspended
matter and deposition on to the sea¯oor (Bohem et al.,
1982; Wang et al., 1997b; Garret et al., 1998). Weathering processes involved, together with the chemical
nature of the spilled oil, determine the fate and rate of
degradation. The weathering processes under natural
conditions are complicated and depend on a variety of
* Corresponding author. Fax:+972-7-6472997.
E-mail address: [email protected] (S. Ezra).
factors. Therefore, studies of weathering under natural
conditions are essential for the understanding of these
processes in the natural environment. Each weathering
process may have a dierent eect on the oil components (e.g. Connan et al., 1980; Boehm et al., 1982;
Volkman et al., 1984; Rowland et al., 1986; Wang and
Fingas, 1995a,b; Fisher et al., 1996; Budzinski et al.,
1998; Sauer et al., 1998; Garrett et al., 1998). Thus,
variation over time in the composition of dierent oil
constituents can be used to monitor the extent of
weathering. A detailed understanding of weathering
processes that oil is subjected to is required in order to
reduce environmental damage and develop eective
protection strategies.
On 8 February, 1998 residual fuel oil from the Eshkol
power station, north of Ashdod harbour, spilled as a
result of a technical failure. The fuel spilled into the sea
through the cooling water outlet system and formed an
elongated ¯oating lens in the nearshore that was transported by the waves. It also landed on the beach and
polluted a 9 km stretch of the coastline. The coastline
polluted by the spill is generally characterized by sandy
0146-6380/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved.
PII: S0146-6380(00)00091-7
1734
S. Ezra et al. / Organic Geochemistry 31 (2000) 1733±1741
beaches with scattered beach rock boulders, partially
exposed due to sand mining in the 1950s. The spill provided an excellent opportunity to monitor, with relatively
high resolution, the variation in the chemical composition of the spilled residual oil over time and characterize
the weathering processes in the Israeli coastline of the
east Mediterranean under natural conditions. Systematic sampling at the polluted shore started about 48 h
after the spillage began, at a time when the beaching of
tar was still occurring. Moreover, knowledge of the
source fuel provided a reference composition and the
possibility to extend the control on the weathering processes back in time to their initiation (`zero time').
2. Experimental
2.1. Samples
Systematic sampling of the polluted shore stretch
commenced 48 h after the spill began and continued for
more than a year. The residual oil pollution (tar patches) was sampled at three stations (Fig. 1), each comprising several sampling points of sand and beach rocks.
Sand sampling points lasted for only about one month,
before they were washed away. Contamination patches
on rocks were persistent throughout the study period and
were sampled continually for 14 months. Sampling was
carried out at 2 weekly intervals during the ®rst 4 months
and subsequently once a month, on the basis of the initial
results. A sample of the initial residual fuel oil was
obtained from the Eshkol power station fuel container.
Samples were stored in sealed vials and kept at 5 C.
2.2. Extraction and liquid chromatography
The samples were solvent extracted with toluene.
Asphaltenes were precipitated from the extracted fraction with n-hexane (50:1 hexane:toluene). The deasphalted extracts were fractionated using column
chromatography (30 cm length and 1 cm width column
®lled half with activated alumina and half with activated
silica gel). Approximately 100 mg of deasphaltened
fraction was adsorbed on to the top of the column. The
aliphatic fraction was recovered by eluting with hexane
(300 ml), the aromatic fraction with toluene (300 ml)
and the resins with methanol (200 ml).
2.3. Gas chromatography (GC)
Aliphatic fractions were analyzed on a Hewlett Packard (HP) 5890 FID gas chromatograph with a HP-5
fused silica column (30 m, 0.32 mm i.d., 0.25 mm ®lm).
The injector and the detector were held at 300 C and the
column temperature program was 50 C (2 min), followed by heating to 300 C at 4 C/min (isothermal hold
for 20 min). The carrier gas used was He.
2.4. Gas chromatography±mass spectrometry (GC±MS)
Fig. 1. Location of polluted coast and sampling sites. AN, AC
and AS represent, respectively, the northern, central and
southern sampling stations.
Aliphatic and aromatic fractions of selected samples
were analyzed by GC±MS. Scanning of polycyclic
alkanes was performed using a HP 57904A GC directly
connected to a ZAB- II F (VG analytical) double-focusing MS. The GC was equipped with a DB-5 fused silica
column (30 m, 0.32 mm i.d., 0.25 mm ®lm). The injector
and the detector were held at 300 C. The MS operated in
selected ion resolution (SIR) mode. The ions monitored
were m/z 191.1800 for hopanes and m/z 217.1956 and
218.2035 for steranes. To obtain spectral data and identi®cation of the PAH compounds a HP 5890 GC directly
connected to an HP 5971A MS was used. The GC was
equipped with a HP-1 fused silica column (30 m, 0.20 mm
i.d., 0.33 mm ®lm). The injector and the detector were
held at 280 and 250 C, respectively. The MS operated in
a single ion monitoring (SIM) mode. The ions monitored
were m/z 128, 142 and 156 for naphthalene and alkylnaphthalenes; m/z 178, 192 and 206 for phenanthrene
and alkylphenanthrenes; m/z 184, 198 and 212 for
dibenzothiophene and alkyldibenzothiophenes; and m/z
166, 180 and 194 for ¯uorene and alkyl¯uorenes. The
column temperature program for both GC±MS instru-
S. Ezra et al. / Organic Geochemistry 31 (2000) 1733±1741
ments was at 50 C (2 min), followed by heating to
300 C at a 4 C/min rate (isothermal hold 20 min).
3. Results
3.1. Aliphatics
Fig. 2a±c shows C15+ gas chromatograms obtained
for the n- and isoalkanes in the residual fuel oil sampled
from the power station container and two tar samples
(station AC) obtained at 3 and 30 weeks after the spill.
The n-alkane envelope in the residual fuel oil (Mazut)
from the power station container is characterized by nalkanes ranging from C13 to C35 maximizing at n-C22
(Fig. 2a). Subsequently, there is an absence of aliphatic
compounds