Journal of Environmental Protection, 2011, 2, 545-554
doi:10.4236/jep.2011.25063 Published Online July 2011 (http://www.scirp.org/journal/jep)
Distribution of Different Organotin and
Organolead Compounds in Sediment of Suez Gulf
Mohamed A. Shreadah1, Tarek O. Said1*, Safaa A. Abd El Ghani1, Abd El Moniem M. Ahmed2
1National Institute of Oceanography and Fisheries, Kayet Bay, Alexandria, Egypt; 2Chemistry Department, Faculty of Science,
Alexandria University, Alexandria, Egypt.
Received January 2nd, 2011; revised March 7th, 2011; accepted April 11th, 2011.
ABSTRACT
Organotin and organolead compou nds were determined in sediments of the Suez Gulf. The con centra tion s of Tributyltin
(TBT) ranged from 0.27 to 2.77 with an average value of 1.37 µg·g–1; dry wt. However, the concentrations of dibutyltin
(DBT) ranged from 0.07 to 2.27 with an average value of 0.58 µg·g–1; dry wt. A significant correlation was found be-
tween TBT and DBT with r = 0.82, (p = 0.05) indicating that the occu rrence of DBT is mainly related to the degrada-
tion of TBT. Generally, the high concentration of TBT was attributed to shipping activity in harbours. In addition, Di-
phenyltin (DPhT) concentrations ranged from not detected to 2.09 with an average of 1.10 µg·g–1 dry wt. Antifouling
agents, industrial discharge and the influence of sewage discharge are the main sources of pollution by DPhT com-
pounds in Suez Gulf. On the other side, organolead (OLC) concentrations ranged from 10.88 - 440.2 with an average of
168.7 ng·g–1; dry wt. A significant setting of OLC recorded in sediments of Suez Gulf was mainly attrib uted to cars ex-
haust and/or spelling and direct evaporation of fuels.
Keywords: Organotin, Organolead, Se diment , Suez Gulf, Egy pt
1. Introduction
Organometallic compounds have different toxicological
behavior compared to that of nonorganic compounds of
the respective elements. Under environmental conditions
metal-carbon bonds of the elements Sn and Pb are stable
[1]. Organotin (OT) compounds have a broad range of
applications and they are among the most widely used
organometallic chemicals. Monobutyltin (MBT) and di-
butyltin (DBT) compounds are used as thermal and UV
stabilizers of polyvinylchloride (PVC) and as catalysts in
the production of polyurethane foams and silicones. Tri-
butyltin (TBT) and triphenyltin (TPhT) have been used
as antifouling agents in pleasure boats, large ships and
vessels, harbor structures, and aquaculture nets, as well
as agrochemicals and general biocides [2]. Various bio-
logical effects as a result of OTs exposure have been well
documented. TBT, among OTs is of the most concern
due to its direct introduction into the environment and its
high toxicity; it has been shown that it was toxic to many
embryonic and larval organisms even at low concentra-
tions [3]. TBT compounds caused the reduction of mol-
lusks growth [4], shell thickening in Pacific oysters [5]
and imposex in gastropods [6-8]. Organotin compounds
were measured in sediments of four different semi-en
closed areas of the Mediterranean coast of Alexandria:
the Eastern Harbor, Western Harbor, El-Max Bay and
Abu-Qir Bay [9].
Due to the commercial trade activity inside the West-
ern Harbor, in addition to the effect of wastes discharged
from El Noubaria canal, it shows the highest concentra-
tions of total tin (6.34 μg·g–1 dry wt), dibutyl tin (1.63
μg·g−1 wet wt), tributyl tin (0.33 μg·g−1; wet wt) and di-
phenyl tin (1.06 μg·g−1; wet wt) compared with other
locations.
During the past decade it became gradually recognized
that exploring and monitoring the concentration levels of
the various ionic organolead species in the environment
would be of major importance for a double reason; to
elucidate a possible bio-geochemical cycle of lead and to
paint out possible adverse effects, on man and the envi-
ronment, associated with the wide spread use of tetra
alkyllead compounds (TAL; PbR4, R = methyl or ethyl)
as antiknock agents in gasoline. Tetraethyllead (TEL)
and tetramethyllead (TML) were produced world-wide as
anti-knocking additives for gasoline to increase octane
numbers. The use of leaded gasoline over almost one
century caused a ubiquitous pollution of the environment

Distribution of Different Organotin and Organolead Compounds in Sediment of Suez Gulf 546
with lead ions or alkyllead compounds [10]. Dialkyllead
and trialkyllead, which are relatively soluble in water and
considerably more stable than the initial compounds, is
believed to be derived from anthropogenic sources such
as effluent from alkyllead production plants as well as,
naturally, through the slow degradation of tetraalkyllead
in the environment. Degradation products, finally yield-
ing inorganic lead, are either adsorbed on particulates,
accumulated by organisms or recycled to the atmosphere
by volatilization through methylation [11].
In spite of increasing activities which lead to the
OMCs pollution along the Egyptian Red Sea coasts.
These activities include transportation mainly through
the Suez Canal, loading and unloading, transit area, in-
dustrial activities in the Suez Gulf, in addition to urban
run-off and domestic wastes of costal towns distributed
along the Red Sea coasts. The investigations of OMCs
specially organotin and organolead in the Suez Gulf still
need much more efforts to give us a clear picture of ex-
tent of pollution by these compounds. The aim of the
present work was to assess the concentrations of different
types of organotin and organolead species in sediment of
Suez Gulf to provide information about their distribution
and occurrence and elucidate their fate by using the most
recent advances in the field of analytical chemistry.
2. Materials and Methods
2.1. Study Area
Suez Gulf is a narrow shallow water body covering an
area of about 7,500 km2 with 250 km long, 32 km width
and 45 m average depth [12]. It is considered as the most
polluted area in the Red Sea [13-16]. It is located be-
tween longitude 32 50_ to 3°00_ E and latitude 27°50_ to
57°71_ N. It has 11 km as a proper transitional area at the
Suez Bay–Suez Gulf and the width increases to 19 km at
Ras Matarma and 45 km at Ras Abu Zenima. It is a tran-
sit area for ships passing to and from the Suez Canal.
Moreover, several industries have been established along
the western coastal such as refineries, fertilizer plant,
power stations, and dry docks which are closed to Port
Tawfiq region. Ten Stations were selected to cover the
expected polluted sites due to industrial and other activi-
ties in the Suez Gulf (Figure 1).
2.2. Sampling and Analyses
Coastal sediment samples were collected three times
from 10 stations in depths ranged from 4 - 6 m after tidal
zone using a Hydro-Bios stainless-steel grab sampler
during winter and kept frozen at –20˚C, until analysis.
The water content (WC) of each sample was determined
Figure 1. Sampling stations along the Suez Gulf.
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Distribution of Different Organotin and Organolead Compounds in Sediment of Suez Gulf547
by drying a representative sample in an oven at 105˚C
overnight to a constant weight. Moreover, organic carbon
was determined using acid/dichromate titration method
[17]. Grain- size analysis was carried out using the con-
ventional method [18]. About 30 g of washed and quar-
tered dried sample was subjected to the combined tech-
nique of dry sieving and pipette analysis. Porosity % was
calculated according to the equation Porosity =
(WC/1.02)/[(1–WC)/2.64 + WC/1.02] [19]. Total tin and
total lead compounds in sediment samples were deter-
mined according to UNEP/IAEA [20]. 0.5 g of dry sedi-
ment sample was completely digested in Teflon vessels
using a mixture of HNO3, HF and HClO4 (3:2:1 V/V)
and triplicate digestions were made for each sample. The
final solution was diluted to 25 ml with distilled de-ion-
ized water. All digested solutions were analyzed by using
inductively coupled plasma instrument; ICP (Spectro
Analytical instruments Gmbh, Boschstra Be 10, D-47533
Kleve/Germany, 7431/95). Accuracy and precision were
checked by using reference material (SD-M-2/IM marine
sediment) provided by the National Research Council of
Canada (Analytical results of the quality control samples
indicated a satisfactory performance of heavy metals
determination within the range of certified values with
90.4% - 97.5% recovery for studied metals. Organotin
compounds; TBT, DPhT and DBT were determined ac-
cording to Tsuda. et al. [21] as follows; ten grams of se-
diment was placed into 500 ml separating funnel, and
extracted for 30 min with 50 ml ethyl acetate after adding
50 ml water and 5 ml HCl. The mixture was centrifuged
at 2500 rpm for 5 min and 30 ml of organic layer were
transferred to 50 ml round-bottom flask. The organic
layer was evaporated nearly to dryness (0.1 ml) in vac-
uum at 40oC. The residue was dissolved in 1 ml ethanol,
2 ml hydrogenation reagent (1 g of NaBH4 dissolved in
40 ml ethanol) was added with shaking, and let for
standing for 10 min at room temperature. Five ml of wa-
ter was added to the reaction mixture, shacked slightly,
and transferred to 50 ml separating funnel. The flask was
rinsed with 5 ml portions of water, and transferred to the
funnel then extracted for 5 min with 5 ml hexane after
adding of 5 g NaCl. Hexane was passed through silica
gel column to elute butyltin hydrides. The first 20 ml was
collected in round-bottom flask, evaporated to about 2 ml
under reduced pressure at 40˚C. (The concentrate was
transferred into 5 ml gradual test tube, rinsing flask with
hexane, and the volume was adjusted to 1 ml under ni-
trogen stream in 40˚C dry bath. The final extract was
then injected into gas chromatograph/electron capture de-
tector, GC/ECD (HP 5890 II). The chromatographic
column was HP-5 capillary column (30 m × 0.32 mm ×
0.25 µm); 5% diphenyl and 95% dimethyl polysiloxane,
non-polar 60 to 325˚C) with N2 as carrier gas with flow
rate of 2 ml/min. The injection port and detector line
were at 300 and 310, respectively. The column was pro-
grammed from 80˚C for 3 min to a final 310˚C for 8 min
at a rate 5˚C /min.
Organolead compounds (tri-alkyllead and tetraal-
kyllead) were determined according to Chau et al. [22] as
follows; about 5 g of sediment samples was extracted in
a capped glass vial with 3 ml benzene after addition of 10
ml H2O, 6 g NaCl, 1g potassium iodide, 2 g sodium
benzoate, 3 ml of 0.5 mol/l sodium diethyldithiocar-
bamate (NaDDTC) and 2 g coarse glass beads (20 - 40
mesh) with stirring for 2 h in mechanical Shaker. After
centrifugation of the mixture, a measured aliquot (1 ml)
of benzene was taken for butylation. Derivatization was
carried out by adding 0.5 ml butyl Grignard reagent (bu-
tyl magnesium chloride; Sigma Aldrich, USA) to the
sample. The mixture was gently shacked for 10 min, and
washed with 5 ml of 0.5 M sulfuric acid to destroy the
excess of Grignard reagent. About 2 - 3 ml of the organic
phase was pipetted into a small vial and dried with anhy-
drous sodium sulfate. Appropriate amounts (3 - 5 µl)
were injected into gas chromatograph/flame ionization
detector (GC/FID). The sample extract was introduced
directly to the chromatographic column by micro-syringe.
The chromatographic column was HP-5 capillary column
(30 m × 0.32 mm × 0.25 µm); 5% diphenyl and 95%
dimethyl polysiloxane, non-polar (60 to 325˚C) with N2
as carrier gas with flow rate of 2 ml/min. The injection
port and detector line were at 150 and 200˚C, respec-
tively. The column was programmed from 60˚C to 200˚C
at a rate 8˚C/min.
2.3. Method Validation and Quality Control
Studies
Method validation and quality control samples were done
using standard solutions and applying the computerized
4.3 quality system provided by DANIDA from VKI.
Two natural samples were analyzed in duplicate in each
of six batches of samples after spiking by a known con-
centration of the standard solution. The same two natural
samples were analyzed without spiking. The highest and
lowest percentages of recovery for spiked samples were
used to determine the accuracy which ranged between 90
and 105%.
3. Results
3.1. Grain Size
A thorough sight on data of Table 1, indicated that sandy
sediments are dominant at most of the area of investiga-
tion. The mean size of sediments ranges from 2.03Ø at
station II (El Zaitia Harbour) to 0.19Ø at station VII (Ras
Gharib), i.e. from fine to course sand. However, sorting

Distribution of Different Organotin and Organolead Compounds in Sediment of Suez Gulf 548
values vary from 0.65 to 1.47 (i.e. from moderately well
sorted to poorly sorted) reflected unstable condition in
the Suez Gulf. Folk (18) stated that the most the skew-
ness value departs from zero, the greatest the degree of
asymmetry. About 70 % of the samples of investigation
are positively skewed (i.e. finely skewed), this clearly in-
dicates the asymmetry of sediments in the Suez Gulf. The
same is true for Kurtosis values ranging from 0.45 at sta-
tion III (El Kabanon) to 1.11 at station V (Adabiya Port).
3.2. Water Percent and Porosity Percent
Water percent is an important factor in controlling the
early digenetic processes of sediments. It affects the rate
of reactions particularly, the Redox processes, pH and
the amount of organotin compounds that may be trapped
due to their hydrophobic characteristics. Water percent
reflects the ability of sediments to hold water molecules
between their particles, which are mainly a function of
particle size and mineral composition [23].
Water percent of the Suez Gulf sediments is ranged
between 13.55% and 54.54%. The maximum absolute
value of 54.54% was observed at station II; while the
minimum absolute value 13.55% was observed at station
VIII, this reflects the effect of the nature of coarse sandy
sediment at this station. The porosity ranged from 6.11%
at station VII to 37.79 % at station I (Table 2).
3.3. Total Organic Carbon (TOC)
Organic carbon contents ranged from 0.01% to 2.95%
with an average value of 0.67% (Table 2). The maxi-
mum values were observed at stations I and II, and this
may be due to the influence of industrial wastewater pro-
duced by discharging about 93 tones of heavy petroleum
fractions annually into the bay from two large refineries
(Suez petroleum and El Nasr petroleum companies [24].
Moreover, El-Zeitia Harbor station (II) considered one
of the heaviest loading and unloading operations of oil
tan- kers in the world [25]. On the other hand, it pol-
luted by the discharge of both agriculture and domestic
wastes from cities distributed along the Suez Canal. (A
good correlation between TOC and water contents in
sediment of the Suez Gulf was observed r = 0.82 (p =
0.05). The minimum absolute value of 0.01% was ob-
served at station VI revealed that this station is not sub-
jected to the influence of industrial or domestic dis-
charge.
Table 1. Grain size analysis of sediment samples collected from Suez Gulf during 2005.
St. No. Gravel % Sand % Pan % Ø Sk Ku Type of Sand Sorting
I 0 100 0 2.02 0.07 0.77 Fine sand 0.67 (Moderately well sorted)
II 0 100 0 2.03 0.13 0.85 Fine sand 0.72 (Moderately sorted)
III 48.86 50.9 0.24 0.32 0.53 0.45 Coarse sand 0.97 (Moderately sorted)
IV 19.08 76.45 4.45 0.32 0.53 0.45 Coarse sand 0.97 (Moderately sorted)
V 15.57 80.24 4.19 1.83 –0.18 1.11 Medium sand 1.47 (Poorly sorted)
VI 0 100 0 2.02 0.42 0.99 Fine sand 0.87 (Moderately sorted)
VII 61.06 38.87 0.07 0.19 0.61 Coarse sand 0.94 (Moderately sorted)
VIII 27.01 72.9 0.09 0.82 –0.3 0.74 Coarse sand 1.01 (Poorly sorted)
IX 0.72 97.62 0.66 0.97 0.13 0.75 Coarse sand 0.65 (Moderately well sorted)
X 3.66 95.63 0.71 1.98 0.06 0.9 Medium sand 0.76 (Moderately sorted)
W: water percent, P: porosity, TOC: total organic carbon, TC: total carbonate, Si: silicon content, * cited from Shreadah et al. [42].
Table 2. Physico-chemical parameters of the sediment samples collected from Suez Gulf during 2005.
I 43.06 37.79 1.65 50 12
II 54.54 26.92 2.95 - -
III 37.88 22.53 0.35 54 13.2
IV 31.12 17.26 0.35 42 22.5
V 38.76 23.25 0.80 60 9.9
VI 14.21 6.460 0.01 66 11.7
VII 17.98 8.580 0.10 28 31.8
VIII 13.55 6.110 0.30 22 26.7
IX 21.03 10.41 0.05 42 19.4
X 33.84 19.32 0.20 21 10.6
W: water percent, P: porosity, TOC: total organic carbon, TC: total carbonate, Si: silicon content, * cited from Shreadah et al. [42].
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Distribution of Different Organotin and Organolead Compounds in Sediment of Suez Gulf549
3.4. Total Tin and Total Lead Compounds
Concentrations of total lead ranged from 25 to 81 (μg·g–1;
dry wt) in the area of study (Figure 2). High values were
measured at stations I, V, VIII and X. This may be due to
industrial and domestic effluents as well as the atmos-
pheric deposition besides the contribution of Pb from the
leaded petrol in outboard boat engines and oil refineries
in this area. Comparing concentrations measured in the
present study to those observed by previous workers, one
can easily find that the concentrations of Pb increased
significantly from 1992 to 1998 then decreased during
2002 and increased again during 2005 (Table 3). This
may reflect that Pb is strongly affected by the industrial
developments and increasing human activities in the
Suez Gulf. The concentrations of Pb were observed to be
Figure 2. Relationship between total lead and tin concentra-
tions with organic carbon % for sediment samples collected
from Suez Gulf during 2005.
Table 3. Comparison between total lead and total Tin con-
centrations (μg·g–1; dry wt) in sediments of the Suez Gulf
during 2005 and those recorded by others.
Area Range (μg·g–1, dry wt) References
Pb
Suez Gulf (2005) 25 - 81 Present study
Suez Bay (2005) 25 - 69 Present study
Suez Bay (1993-1994) 14 - 28 [26]
Suez Bay (1997-1998) 22 - 91 [27]
Suez Bay (2002) 20 - 40 [28]
Suez Gulf (1999) 71 - 100 [29]
Background level 20 - 30 [30]
Sn
Suez Gulf 4 - 30 Present study
Western Harbor, Egypt 3 - 6 [9]
Riade Aroua, Spain 5 - 21 [31]
Gipuzloa, Spain 11 - 113 [32]
Gulf of Codiz, Spain 8 - 24 [33]
higher than the background level (20 - 30 μg·g–1) [30].
Total tin concentrations ranged between 4 and 30
(μg·g–1; dry wt) with an average value of 14 μg·g–1. The
maximum value of 30 μg·g–1 was observed at station II
(El Zeitia), this station is affected mainly by heavy oil
processing and ships discharge containing organotin
compounds as antifouling paints. On the other hand, the
high value of 25 μg·g–1; dry wt measured at station IX;
was attributed to the fact that this area is subjected to
high oil field activities distributed at Ras Shukhir, in ad-
dition to the presence of a large amount of decayed algae.
Algae can accumulate inorganic tin compounds and ul-
timately remove tin from water and release it to the at-
mosphere by the formation and release tetramethyltins
[34]. It was found that total tin concentrations in marine
macro algae varied between 0.5 and 101 mgk–1; dry wt
and demonstrated that most species of aquatic flora
bio-concentrate tin from seawater [35].
Minimum value of 4 μg·g–1 was detected at station IV
(NIOF) and revealed that this station is not subjected to
the influence of industrial or sewage discharge i.e., far
from inputs of tin compounds. Lin and Chen [36] stated
that grain size was found to be one of the major factors
controlling heavy metals distribution in sediments. The
sediments in our area of investigation were mainly sand,
thus the total metal concentrations were not grain size
controlled with r = 0.4 between total metal concentration
and mean size of each sediment sample. Total tin con-
centrations were found to have a positive significant cor-
relation with organic carbon content with r = 0.64; (p =
0.05). Figure 2 shows that there is a correlation between
TOC and both Sn and Pb particularly in stations I toV
and this related to anthropogenic sources especially in
stations III and IV. However, a weak correlation was
observed for stations VI to X reflecting low content of
organic carbon, i.e. , low pollution index for such stations
especially at stations VI and IX. Table 4 shows the
comparison between total tin concentrations in the pre-
sent study with other studies at similar areas. We found
that the concentration of total Sn measured along the
Suez Gulf were comparable with that observed in Riade
Aroua and Gulf of Codiz, Spain. However, it was higher
than that observed in Gipuzloa, Spain and Western Har-
bor, Egypt (Table 3).
3.5. Organotin Compounds
3.5.1. Tributyltin (TBT) Species
Concentrations of TBT in the investigated area ranged
between 0.27 to 2.77 μg·g–1; dry wt with an average val-
ue of 1.4 μg·g–1 (Table 4). It is clear that TBT is the
predominant species of OTC with a ratio to total OT spe-
cies ranged from 20 to 75%. The maximum value of 2.8

Distribution of Different Organotin and Organolead Compounds in Sediment of Suez Gulf 550
Table 4. Concentrations of organotin species (μg·g–1; dry wt) and organolead species (ng·g–1; dry wt) in sediment samples
collected from the Suez Gulf during 2005.
St. TBT DBT DPhT TOT Et4Pb Me4Pb Et3Pb Me3Pb TOL
I 0.51 ± 0.02 0.19 ± 0.021.32 ± 0.03 2.0213.58 ± 0.2219.30 ± 0.41 126.59 ± 0.51 13.59 ± 0.36 173.06
II 2.77 ± 0.25 2.27 ± 0.122.09 ± 0.04 7.134.88 ± 0.11 15.09 ± 0.14 22.44 ± 0.71 10.78 ± 0.59 53.19
III 0.27 ± 0.03 0.08 ± 0.010.98 ± 0.03 1.3471.27 ± 0.2734.06 ± 0.10 3.59 ± 0.05 20.70 ± 0.55 129.62
IV 0.81 ± 0.09 0.07 ± 0.010.89 ± 0.05 1.7774.48 ± 1.23210.74 ± 1.87 4.57 ± 0.27 150.73 ± 0.65 440.52
V 2.19 ± 0.13 1.32 ± 0.031.44 ± 0.05 4.9535.60 ± 0.50203.38 ± 0.58 25.42 ± 0.86 162.49 ± 0.37 426.89
VI 1.50 ± 0.10 0.48 ± 0.03<DL 1.98<DL 47.13 ± 0.61 <DL 35.13 ± 0.41 82.26
VII 0.35 ± 0.04 0.11 ± 0.010.82 ± 0.03 1.280.59 ± 0.03 2.27 ± 0.14 3.18 ± 0.20 4.84 ± 0.16 10.88
VIII 1.11 ± 0.18 0.22 ± 0.010.99 ± 0.02 2.334.04 ± 0.05 63.96 ± 0.75 1.23 ± 0.08 61.16 ± 0.27 130.38
IX 1.87 ± 0.18 0.42 ± 0.021.13 ± 0.05 3.4242.31 ± 0.1223.90 ± 0.78 8.38 ± 0.33 13.44 ± 0.49 88.02
X 2.31 ± 0.20 0.60 ± 0.051.33 ± 0.05 4.253.37 ± 0.25 13.97 ± 0.23 121.49 ± 0.65 12.94 ± 0.31 151.77
Av. 1.37 0.58 1.1 3.0525.01 63.38 31.69 48.58 168.66
<DL: below the detection limit, Av. = average value for triplicate analyses, TOT = Sum (TBT+ DBT+DPhT), TOL = Sum (Et4Pb + Me4Pb + Et3Pb+ Me3Pb).
μg·g–1 was observed at station (II); Zeitia Harbor which
has high contents of total organic carbon with 2.95%. It
has been reported that the organic carbon content of se-
diments affects the bioavailability and toxicity of TBT i.e.
sediments with high concentration of organic matter may
act as sink for TBT [37,38]. In addition it situated near
the shipyard dry dock in which TBT compounds are used
in painting the hulls of new vessels and on older vessels
during dry docking. The average TBT content in marine
paints was about 4%, and approximately 1200 tons of
TBT was applied annually to ships hulls [39]. On the
meantime, high concentrations of TBT were also found
at stations V, VI, IX and X where, station V (El Adabiya
port) is affected by loading and unloading activities. In
addition to the wastes of some industries such as vegeta-
ble oil factories and chemical industries near this station
and wastes discharged from Attaqa power station, at
which TBT compounds are used as a biocide for cooling
waters. Station VI (El Sukhna) is considered as transit
area of ships passing through the Suez Canal. It was re-
ported that, during 3-days stay inside a harbor, a com-
mercial ship, leaching TBT at the constant leach rate, can
release more than 200 g TBT into water [40]. However,
if freshly painted, this amount can reach 600 g, which
can result in a dissolved TBT contamination of the sur-
rounded water ranging between 100 and 200 or about
600 ng·Snl–1, respectively. Station IX (Ras Shukier) is a
large center for collection and shipment of oil from sev-
eral oil fields including off shore wells. The high value of
TBT observed at station (X); El Tour was attributed to
the high intensity of fishing boats activities which use
TBT in antifouling paints. on the other hand, the rela-
tively low concentration of 0.27 μg·g–1 dry wt found at
station III+ is mainly due to the coarse sand nature of
sediment. A good significant correlation was observed
between TBT and mean size (Ø) with r = 0.67 (p = 0.05).
Therefore, TBT accumulated in sediments of the Suez
Gulf was affected by grain size.
It has been reported that The Australian sediment
quality guidelines for TBT are 5 ng·g–1 and 70 ng·g–1 for
low and high threshold values [41]. The concentrations
of TBT in sediment samples from 10 stations along the
Suez Gulf were found to be higher than the highest thre-
shold value, suggesting these sediments may pose a
threat to a benthic biota. Moreover, high levels of TBT in
Suez Gulf sediments reflects its widespread contamina-
tion and could be an indicative of the continuing usage
of TBT- based antifouling paints on ship hulls.
Shereadah et al. [42] investigated the mineralogical
composition of surficial sediments along the Egyptian
Red sea coast during 2006. They indicated that in Suez
Gulf, the average value of total carbonate (TC %) = 42%
while the average value of Si% = 19.4 (Table 2). This
indicated that the composition of sediment in our area of
investigation is mainly carbonate meaning that sediments
are weak adsorbents and prone to digenesis and redisso-
lution. However, the relatively high concentrations of
TBT recorded in sediments of the Suez Gulf result from
renewal source of contamination by such compounds
rather that adsorption to sediment.
Dowson et al. [37] have introduced a classification for
TBT concentrations in sediments, characterizing concen-
trations below 3ngg-1 as uncontaminated, 3 - 20 ng·g–1 as
light contaminated, 20 - 100 ng·g–1 as moderately con-
taminated, 100 - 500 as highly contaminated and above
500 ng·g–1 as grossly contaminated. Following this scheme,
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Distribution of Different Organotin and Organolead Compounds in Sediment of Suez Gulf551
the sampled surface sediments in the Suez Gulf are con-
sidered as highly to grossly contaminate.
3.5.2. Dibutyltin (DBT) Species
Dibutyltin concentrations varied from 0.07 to 2.27 μg·g–1;
dry wt with an average concentration of 0.58 μg·g–1; dry
wt. (Table 4). A significant correlation with r = 0.82 (p =
0.05) was found between the concentration of TBT and
DBT reflecting the degradation of TBT as a main source
of DBT in the Suez Gulf. The maximum value of DBT
was observed at station (II) due to 1) the direct emission
or the degradation of TBT to DBT at surface water as
mentioned by [43-49] and microbial degradation of TBT
to DBT and MBT in oxic and anoxic sediments [50], 2)
high value of organic carbon content 2.95 % in sediments.
The minimum absolute value of DBT 0.07 μg·g-1;dry wt
at stations (III and IV) may be attributed to the type of
sediment (coarse sand).In general, the concentration of
TBT was greater than DBT in sediments of the Suez Gulf
and the TBT/DBT ratio showed large variation from 1.22
to 11.20. High TBT/DBT ratio may be attributed to re-
cent input of TBT and/or to low degradation of TBT to
DBT into these stations. It is known that TBT degrada-
tion rates in sediment are slower than in water column,
particularly in anaerobic conditions. The half life of TBT
in sediments is in the range of years rather than days or
weeks in the water column [51]. Although abiotic degra-
dation occurs, the process remains less important than
biological action [52]. Microbial degradation of TBT to
DBT and MBT takes days to weeks in water, years in
oxic sediments and more than that in anoxic sediments
[50]. The degradation products have generally been as-
sumed to be less toxic than TBT because they are less
lipophilic. Furthermore, bacterial communities degrading
TBT might be dependent on salinity and other environ-
mental factors [53].
3.5.3. Diphenyltin (DPhT) species
A thorough sight on data of Table 5 indicated that di-
phenyltin (DPhT) species showed relatively high con-
centrations at the stations along the Suez Gulf. This may
be due to the influence of sewage and industrial (refiner-
ies and textile companies) discharge. DPhT concentra-
tions in the Suez Gulf were < 2.09 μg·g–1; dry wt with an
average concentration of 1.09 μg·g–1dry wt. The maxi-
mum absolute value of DPhT 2.09 μg·g–1; dry wt ob-
served at station (II), is due to the use of triphenyltin as
antifouling agents in ship paints and discharged of the
agricultural wastewater from the Suez Canal. According
to Odoyemi et al. [54] high concentrations of butyltin
and phenyltin derivatives are possibly due to using them
in agricultural and industrial activities or high sorption
affinity onto soils. However, the occurrence of butyltin
and phenyltin derivatives in an aquatic environment
could be a result of sewage sludge and high degradation
of triphenyltin to phenyltin derivatives (mono and di
phenyltin) [55].
Previous studies revealed that TBT is toxic to aquatic
biota at concentrations of >2 ng·l−1 [56]. Regarding to
the production, usage, accumulation, and toxicity of or-
ganotin compounds. Based on the results obtained from
the present study, we can conclude that the prohibition of
using organotin in antifouling paints is an effective ac-
tion for both the protection and conservation of marine
life. Furthermore, detecting the average concentration
values 1.37, 0.58 and 1.10 (μg·g–1) for TBT, DBT, and
DPhT, respectively in our investigated areas proves a real
need for enforcing the existing regulations.
3.6. Organolead Compounds (OLC)
Table 4 shows the concentrations of four OLC species in
sediment samples, collected from the Suez Gulf. The
concentrations ranged from not detected - 74.48, 2.270 -
210.7, not detected -126.6 and 4.840 - 162.5 ng·g–1; dry
wt, for Et4Pb, Me4Pb, Et3Pb+ and Me3Pb+, respectively.
However, the concentration of total OLC ranged from
10.88 - 440.2 ng·g–1; dry wt. The results of OLC species
indicated the significant setting of OLC into sediments. It
has been reported that Et4Pb species is expected to be
Table 5. The correlation matrix for different organic pollutants recorded in different stations of the investigated area during
2005.
Parameter TBT DBT DPhT Et4Pb Me4Pb Et3Pb Me3Pb
TBT 1.00
DBT 0.82 1.00
DPhT 0.50 0.68 1.00
Et4Pb –0.31 –0.28 –0.02 1.00
Me4Pb 0.05 0.03 –0.04 0.55 1.00
Et3Pb 0.13 0.01 0.36 –0.29 –0.26 1.00
Me3Pb 0.07 0.05 –0.03 0.48 0.99 –0.26 1.00

Distribution of Different Organotin and Organolead Compounds in Sediment of Suez Gulf 552
absorbed onto suspended solids and sediments in water
column [57]. Table 4 shows relatively high concentra-
tions of tetraalkyllead in sediments of the Suez Gulf.
This is attributed to the presence of renew sources and
the high density of these compounds to sink and spread
along the stream bottom. On the other word, the concen-
tration of Me4Pb is higher than Et4Pb, this reflecting the
biomethylation of inorganic lead or organolead cations to
tetramethyllead [58]. In addition, Et4Pb is more sensitive
to photochemical process than Me4Pb [59], which lead to
higher decomposition of Et4Pb in water column. Trie-
thyllead species show a positive correlation with mean
size (Ø) with r= 0.57(p = 0.05).
Maximum concentrations of 440.2 and 426.89 ng/g;
dry wt of OLC were recorded at stations IV and V, re-
spectively. These stations are located near busy roads of
the Suez city at which antiknock organolead compounds
are emitted from incomplete fuels combustion through
cars exhaust. Besides, spilling and direct evaporation are
possible sources of OLC pollution. In addition, water
circulation could affect the transport mechanism of OLC,
where there is a persistent anti-clock wise circulation in
the Bay causing more pollution in the western side. In-
significant correlation was calculated between total Pb
(μg·g–1 dry wt) and total OLC (ng·g–1; dry wt) with r =
0.13 (p = 0.05) in sediment samples, reflecting the influ-
ence of different sources of lead pollution on these sta-
tions. Table 5 shows that a significant correlation is re-
corded between TBT and DBT, DBT and DPhT, Me4Pb
and Me3Pb with r = 0.82, 0.68 and 0.99 respectively.
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