This article appeared in a journal published by Elsevier. The attachedcopy is furnished to the author for internal non-commercial researchand education use, including for instruction at the authors institution

and sharing with colleagues.

Other uses, including reproduction and distribution, or selling orlicensing copies, or posting to personal, institutional or third party

websites are prohibited.

In most cases authors are permitted to post their version of thearticle (e.g. in Word or Tex form) to their personal website orinstitutional repository. Authors requiring further information

regarding Elsevier’s archiving and manuscript policies areencouraged to visit:

http://www.elsevier.com/authorsrights

Author's personal copy

Baseline

Investigation of heavy metal pollutants at various depths in the Gulfof Izmit

Halim Aytekin Ergül a, Tolga Varol b, Ümit Ay b,⇑a Department of Biology, Kocaeli University, 41380 Kocaeli, Turkeyb Department of Chemistry, Kocaeli University, 41380 Kocaeli, Turkey

a r t i c l e i n f o

Keywords:Heavy metalDeep seawaterAtomic absorption spectrophotometerGulf of Izmit

a b s t r a c t

In this study, we report results concerning the accumulation of heavy metals in seawater from Izmit Bay.The bay was divided into the three parts: the eastern, the central and the western basins. The goal of thisstudy was to determine levels of heavy metals at various depths in the bay between April 2008 and May2010. Liquid–liquid extractions were performed on seawater samples. An atomic absorption spectropho-tometer was used to measure levels of six metals: lead, cadmium, chromium, iron, manganese and zinc.We applied our results to evaluate the status of pollution in the Gulf of Izmit. Significant seasonal differ-ences in metal concentrations and higher concentrations of many metals in water near the shore are evi-dence for uncontrolled release of pollutants in the water.

� 2013 Elsevier Ltd. All rights reserved.

1. Introduction

Seawater pollution is a serious concern for many nations be-cause it is an integral part of environmental pollution worldwide(Multia et al., 2012). Heavy metals and similar pollutants from var-ious sources in the atmosphere and on lands accumulate in theseas where they upset the balance of nature, alter the biologicalenvironment and, consequently, enter the food chain and affect hu-man health (Yu et al., 2012). These pollutants include organic com-pounds, industrial wastes, petroleum derivatives, syntheticagricultural fertilizers, detergents, radioactive materials, pesti-cides, inorganic salts and other chemical substances. Pollution, inturn, may be divided into three categories: physical, biologicaland chemical. Chemical pollution occurs when chemical sub-stances and industrial waste are released, intentionally or uninten-tionally, into nature. Paints, detergents, pesticides and petroleumproducts are examples of chemical pollution. Heavy metal pollu-tion is dominant form of chemical pollution. Heavy metals from,for example, industrial wastes, pesticides and mining operationspersist in the environment and are transferred through the foodchain (Wu et al., 2012). In the sea, the most significant pollutantsare chemical substances that stay in the environment for pro-longed periods of time and have toxic effects. Heavy metals arethe leading form of chemical pollution in seawater. In fact, verylow concentrations of heavy metals are natural components offresh water and seawater. However, due to human activities, metalion levels have increased in many natural water systems. Mining,

petroleum and gas exploration in oceans, industrial manufacturing(e.g., textiles, paints, leather, fertilizers and medicine), householdwaste, agricultural runoff and acid rains all increase metal concen-trations in natural water (Petrooshina, 2003). Limited amounts ofheavy metals positively affect biological characteristics of organ-isms. However, higher amounts of metals negatively the affect bio-logical activity of organisms and upset the balance of organisms inthe food chain (Peakall and Burger, 2003). Thus, seawater pollutionshould be prevented and controlled. Pollution control depends onmonitoring pollutants in seawater and determining their sources.For example, Taymaz et al. (1984) analyzed levels of mercury, cad-mium and lead in samples of sediment, seawater and fish from Iz-mit Bay. These researchers’ study showed that Hg and Cd levelswere high near plants producing chlor-alkali chemicals. The resultswere similar for sediment samples from shore areas and fish. Pekeyet al. (2004) collected water samples from 10 locations in DilStream during two different seasons and determined the amountsof certain elements. Water quality was designated according tometal content. That study showed that Cd, Cr, Cu, Pb and Zn valuesexceeded the highest reference concentration values.

Guhathakurta and Kaviraj (2000) examined the Cd, Pb, Zn andFe concentrations in samples of water, sediment, shrimp and mul-let from India’s Sunderban fresh water lake. Okonkwo et al. (2005)performed a study on three rivers in South Africa and comparedheavy metal levels in water samples taken during the winter andthe summer. Metal concentrations were higher in the winter thanin the summer, most likely because rainwater is added to rivers inthe winter. The Pb concentration was higher than the other metalsin each of these three rivers during both seasons. In this study,seasonal variations in heavy metal pollution were monitored in

0025-326X/$ - see front matter � 2013 Elsevier Ltd. All rights reserved.http://dx.doi.org/10.1016/j.marpolbul.2013.05.018

⇑ Corresponding author. Tel.: +90 262 303 20 12; fax: +90 262 303 20 03.E-mail address: umurege@kocaeli.edu.tr (Ü. Ay).

Marine Pollution Bulletin 73 (2013) 389–393

Contents lists available at SciVerse ScienceDirect

Marine Pollution Bulletin

journal homepage: www.elsevier .com/locate /marpolbul

Author's personal copy

water samples taken from different depths at designated stationswhere industrial activity and biological life co-exist in Izmit Bay.Six metals are the focus of this study: iron, manganese, zinc, cop-per, cadmium and lead. These metals were selected due to theirtoxic effects on living organisms and their presence at measurablelevels in sea water samples.

Sampling stations were located at three different areas in IzmitBay, the east, the west and the central basins (Fig. 1).

Seawater samples were collected at designated depths that de-pended on total basin depth.

Water was obtained at depths given in Table 1 using a Nansenbottle. Samples were collected with the assistance of a Control LBoat with an onboard manual crane from the Kocaeli MetropolitanMunicipality (see Table 1).

Sample collection began in spring 2008 and continued withoutinterruption until spring 2010. We periodically performed sam-

pling in each season at the designated depths in three basins ofthe Izmit Bay. The Nansen bottle was submerged in the sea atthe designated depth and a sample was taken using the manualcrane. Water samples were stored in high-density polyethylenebottles. The night before these bottles were used, they were pre-pared by washing with dilute nitric acid and rinsing with purewater three times. Water samples were placed in portable iceboxes

Fig. 1. Sampling station locations in Izmit Bay.

Table 1Depths for sample collection.

Basin I. Depth II. Depth III. Depth IV. Depth V. Depth

East Surface �10 m �20 m – –Central Surface �10 m �20 m �50 m �80 mWest Surface �10 m �20 m �50 m –

Fig. 2. Seasonal variations in heavy metal concentrations in Izmit Bay during 2008.

390 H.A. Ergül et al. / Marine Pollution Bulletin 73 (2013) 389–393

Author's personal copy

to prevent spoiling and brought to the laboratory shortly after theywere collected. Seawater samples were filtered through coarse fil-ter paper, acidified with HNO3 and adjusted to between pH 1.5 and2.0. The samples were stored at +4 �C.

For the metal analysis, at least three 100 mL aliquots from eachsample were tested in parallel. Samples were adjusted to pH �7–8

and transferred into 250 mL separatory funnels. A ligand solution,10 mL (C2H5)2NCSSNa�3H2O (sodium diethyldithiocarbamate tri-hydrate), and 10 mL methyl isobutyl ketone were added to eachseparatory funnel. Separation funnels were shaken for 5 min andwere left until phases separated. The lower (aqueous) phases weretransferred into a 250 mL separation funnels. Then 5 mL of methyl

Fig. 3. Seasonal variations in heavy metal concentrations in Izmit Bay during 2009.

H.A. Ergül et al. / Marine Pollution Bulletin 73 (2013) 389–393 391

Author's personal copy

isobutyl ketone was added to these lower phases, the funnels wereshaken for 5 min and left to separate. After separation of phases,the upper (organic) phase was extracted and the lower phaseswere discarded. Then, the upper phases were combined and then4 mL deionized water and 1 mL concentrated HNO3 were addedto these upper phases. The funnels were shaken for 5 min againand left for 30 min for separation of phases. After separation ofphases, the upper phases were discarded and the lower phaseswere stored in darkness to be conditioned for analysis with theatomic absorption spectrophotometer (AAS).

Elemental concentrations (lg/L) in water samples from variousdepths in three basins in Izmit Bay are shown (Figs. 2–4). Datafrom the east, the west and the central basins show that dissolvedelement concentrations were higher in winter 2010 than the otherseasons. These concentration variations are thought to be relatedto factory wastes and weather conditions. The highest elementalconcentration in surface water was 419 lg/L of Zn in the centralbasin during winter 2010. The results obtained for the surfacewater in the west basin were inconsistent.

The highest concentration of Zn was 82.0 lg/L in the west basinduring summer 2008. Because difficult weather conditions pre-vented us from performing field works in the west basin in winter2010, no data were obtained. For Fe in the west basin, the highestconcentration was in spring 2010, which differed from Zn. In gen-eral, Zn and Fe concentrations were high. The most important rea-son for inconsistent surface water results was uncontrolledpollution from factory and vessel wastes and other sources. Atgreater depths in the basins, Zn was maximized in winter 2010at a depth of �10 m. In winter 2010, the Zn concentration was418 lg/L in the east basin at �10 m and 703 lg/L in the central ba-sin. When we compared data from a depth of �20 m in the east ba-sin, Zn had the highest concentration. The concentration ofdissolved Fe, which was 447 lg/L at �20 m in the central basin

during autumn 2009, fell to 17.9 lg/L in winter 2010. When wecompared results for the central and west basins at �20 m, Fehad the highest concentrations in both basins. The maximum con-centrations of Fe were observed in autumn 2009 in the central ba-sin and in spring 2010 in the west basin. At a depth of �80 m in thecentral basin, Fe, Mn and Zn reached their highest values in au-tumn 2009 and winter 2010. Metal concentrations in the centralbasin rose higher than other depths. These concentration increasesare related to higher pressures are greater depths and cold condi-tions due to climatic change.

When we considered Cu in the east basin with regard to depthand climate variations, the highest value of 18.1 lg/L was observedin summer 2009 at a depth of �20 m. When we evaluated thedepth and climate variations for each trace element, we observedthat values of Zn and Fe exceeded acute levels from time to time.The highest levels of Cu, Fe, Zn and Mn in the east basin were ob-served in summer 2009 and winter 2010. At the same time, thehighest concentration of Mn in the east basin surface water was2832 lg/L during autumn 2009. This deviation is thought to be re-lated to intense pollution sources, because the analysis is per-formed on surface water. Lead and Cd concentrations areacceptable in the east basin.

Iron, Zn and Mn metals increased far above tolerable levels inthe central basin during autumn 2009 and spring 2010. Concentra-tions of Pb, Cu and Cd were low. The west basin had high levels ofMn, Zn and Fe, while Pb, Cu and Cd concentrations were within tol-erable limits.

When the east, the west and the central basins of Izmit Baywere tested for Cd, this element reached its highest value,6.50 lg/L, in winter 2009. Lead reached its highest values in winter2009 and spring 2009 and increased in winter 2010. Manganasereached its highest value in autumn 2009 and increased in winter2009, following a period when it was relatively constant. High

Fig. 4. Seasonal variations in heavy metal concentrations in Izmit Bay during 2010.

392 H.A. Ergül et al. / Marine Pollution Bulletin 73 (2013) 389–393

Author's personal copy

values of Zn were measured between winter 2010 and spring 2010in most basins. Peak values of Fe were observed between autumn2009 and spring 2010. Copper was the same in summer 2009and autumn 2009 and was usually under the tolerable limits.Although Cu and, particularly, Cd were present at high concentra-tions in the east basin in certain seasons, their overall seasonalaverage concentrations were generally higher at stations near thewest basin. However, concentrations of Fe, Mn, Zn and Pb weregenerally high at stations near the east basin. Metal concentrationsvariations due to, for instance, temperature and dissolved oxygenconcentrations, affect metal dissolution. This study showed thatCu concentrations, in particular, tended to decrease with depthduring summer and increase with depth during winters. In general,Fe and Mn concentrations were low at surfaces and higher in dee-per water. Hydroxides of Fe and Mn have notably low solubilityand this may explain their lower concentrations in surface waters.Variations in Zn, Pb and Cd concentrations through the water col-umn are thought to arise from mixtures, geological structures inthe regions and proximity to industries. In certain cases, Cu andZn concentrations were above tolerable limits. Elevated levels ofCu and Zn are thought to originate from uncontrolled release offactory waste in waters.

Significant seasonal differences in metal concentrations andhigher concentrations of many metals in water near the shoreare evidence for uncontrolled release of pollutants in the water.

In this study, seasonal variations in pollution in Izmit Bay wereanalyzed for 2 years. Water samples taken from different locationsand depths in Izmit Bay were analyzed for heavy metal content.Data showed that Izmit Bay is being affected by sources of pollu-tion located near its east, west and central basins. The close prox-imity of the region to industrial operations caused someinconsistent results. Because measured metal concentrations insome areas are always over tolerable limits, permanent sourcesof pollution are present in these areas. The pollution of sea water,which is the habitat of many living species, harms biological lifeand threatens habitats of sea organisms. Because Pb and Cd levelsdo not vary, there may be few or no sources of Pb and Cd pollutionin the area. However, other metals demonstrated seasonal

variations that are thought to originate from discharge of un-treated water and seasonal effects related to shipping activities.It appears that there is uncontrolled or illegal discharge into IzmitBay by many industrial enterprises in the area. Prevention ofuncontrolled or irregular discharges that threaten the ecosystem,principled port activities and long-term studies control pollutionin Izmit Bay and the surrounding area.

Acknowledgements

We express our thanks to Kocaeli University Research Fund,Linde Gas Company for their support and TÜB_ITAK (Project No.107Y261).

References

Guhathakurta, H., Kaviraj, A., 2000. Heavy metal concentration in water, sediment,shrimp (Penaeus monodon) and Mullet (Liza parsia) in some brackish waterponds of Sunderban, India. Mar. Pollut. Bull. 40, 914–920.

Multia, T.M., Virani, M.Z., Moturi, W.N., Muyela, B., Mavura, W.J., Lalah, J.O., 2012.Copper, lead and cadmium concentrations in surface water, sediment and fish,C. Carpio, samples from Lake Naivasha: effect of recent anthropogenic activities.Environ. Earth Sci. 67, 1121–1130.

Okonkwo, J.O., Mothiba, M., Awofolu, O.R., Busari, O., 2005. Levels and speciation ofheavy metals in some rivers in South Africa. Bull. Environ. Contam. Toxicol. 75,1123–1130.

Peakall, D., Burger, J., 2003. Methodologies for assessing exposure to metals:speciation, bioavailability of metals, and ecological host factors. Ecotoxicol.Environ. Saf. 56, 110–121.

Pekey, H., Karakas�, D., Ayberk, S., Tolun, L., Bakoglu, M., 2004. Ecological riskassessment using trace elements from surface sediments of Izmit Bay(Northeastern Marmara Sea) Turkey. Mar. Pollut. Bull. 48, 946–953.

Petrooshina, M., 2003. Landscape mapping of the Russian Black Sea cost. Mar.Pollut. Bull. 47, 187–192.

Taymaz, K., Yigit, V., Özbal, H., Ceritoglu, A., Müftügil, N., 1984. Heavy metalconcentrations in water, sediment and fish from Izmit bay, Turkey. Int. J.Environ. Anal. Chem. 16, 253–265.

Wu, J.L., Zeng, H.A., Yu, H., Ma, L., Xu, L.S., Qin, B.Q., 2012. Water and sedimentquality in lakes along the middle and lower reaches of the Yangtze River, China.Water Resour. Manage. 12, 3601–3618.

Yu, T., Zhang, Y., Hu, X.N., Meng, W., 2012. Distribution and bioaccumulation ofheavy metals in aquatic organisms of different trophic levels and potentialhealth risk assessment from Taihu lake, China. Ecotoxicol. Environ. Saf. 81, 55–64.

H.A. Ergül et al. / Marine Pollution Bulletin 73 (2013) 389–393 393