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This study aims to assess the impact of the sediment in the potential dredging areas of the Marmara Sea. To that aim, sediments were analyzed for polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and heavy metals, sources were discussed, and toxicity tests were applied. For assessment, lower and upper limits of Turkish draft regulation (L

WOS:000478663100031 PubMed: 31384684 As known, marine dredged materials (DMs) are highly nuisance wastes if they are not correctly reused or removed. In this work, the usability of DMs to the technical terms as manufactured topsoil (MT) in the urban landscaping works is discussed. Firstly, the leaching potentials of DMs were determined according to the related legislations to identify their hazardousness features. Secondly, DMs were subject to some treatment stages such as sieving, desalination, organic amelioration via peat and sheep manure, and pH adjustment to turn into an alternative natural soil pursuant to the British Standard in the scope of soil quality improvement studies as there is not any national standard in Turkey for the production of topsoil from different materials. Then, MT mixtures were prepared with washed and unwashed DM, peat and sheep manure in different mixing ratios (v/v); 33%, 50% and 67% DM, respectively. Consequently, high quality grass seed mixtures used for the landscaping applications were monitored for six months. The results demonstrate the availability of DM as alternative MT in the urban landscaping areas. Thus, important data were obtained as to the use of DM at alternative areas such as green city, green roof, shopping centers, organized industry, etc.

This study describes the potential beneficial use of untreated and treated marine dredged material (DM) in ready-mix concrete (RMC) as a fine aggregate. DMs collected from four Turkish ports/harbours were characterized, assessed according to the National Legislation and transformed into one composite DM. Silica sand was replaced with untreated- and treated-composite-DM (COMP-U/COMP-T) at five ratios (0%, 25%, 50%, 75%, 100%), respectively. Mechanical, durability, leaching, mineralogical/micro-structural properties of DM-based-RMCs were analysed. Concretes having 50% COMP-U and 100% COMP-T met the minimum requirement for C25/30 class RMC. Marine DM can be beneficially used in RMC production; however, DM pre-treatment should be applied. (C) 2016 Elsevier Ltd. All rights reserved.

Bu çalışma, dip taramafaaliyetleri neticesinde ortaya çıkan dip tarama malzemelerinin (DTM) betonuygulamalarında ince agrega olarak faydalı kullanımı için bir yıkama-elemetesisi tasarlanmasını, bu tesise ait ilk yatırım ve işletme maliyetlerininortaya konulmasını ve laboratuvar ölçekli DTM yıkama-eleme denemeleri sonucundaortaya çıkan atıksuyun karakterizasyonunun ve yönetiminin belirlenmesini kapsamaktadır.Bu çalışma ile DTM’nin yıkama-eleme ön işlemine tabi tutulması durumunda yüksekklorür, sülfat ve su içeriğinin giderilerek ince agrega olarak betonçalışmalarında kullanılabileceği, oluşan yıkama-eleme atıksuyununkanalizasyona/denize deşarjına risk oluşturacak herhangi bir kirleticiiçermediği tespit edilmiş olup olası 1.500 m3/gün kapasiteli DTMyıkama-eleme tesisinin ilk yatırım ve işletme maliyetlerinin sırasıyla6.753.600 TL ve 2.366.810 TL ve birim maliyeti ise 6,3 TL/ton olarakhesaplanmıştır., Themanagement of dredging materials (DM), which is generated from marine dredgingacitivities is a global problem. DMs in our country are usually dumped at seaby barges and pose a serious risk to the aquatic environment. In this study,the characterization of the DMs excavated by dredging operations and thecharacterization of their washing wastewaters are determined and the design ofa washing-sieving plant for the beneficial use of DM as a fine aggregate inconcrete applications is carried out. Furthermore the cost analysis of thewashing-sieving plant planned to be established for pilot regions is peformed.The findings of this study indicate that DM can be used as a fine aggregate inconcrete applications in case of subjecting to the washing-sievingpre-treatment process, generated washing-sieving wastewater does not involveany contaminant causing a risk to the sewage/sea discharge. The firstinvestment and operating costs of possible DM washing-sieving plant’s having acapacity of 1,500 m3/day are predicted to be 6,753,600 TL and2,366,810 TL, respectively, and the unit cost is presumed as 6.3 TL/ton.

The levels of Hg, Cd, Pb, Cr, Cu and Zn were measured in the tissues of four edible fish species namely: Diplodus annularis, Pagellus erythrinus, Merluccius merluccius and Mullus barbatus, collected from the Turkish Coast of the Aegean Sea. Except for D. annularis, the levels of Cd and Pb in all fish tissues sampled in Aliaga Bay in 2009 were above the tolerable limits according to the Food and Agriculture Organization of the United Nations (FAO). Hg in P. etythrinus and M. barbatus were higher than the maximum permitted limits (FAO), while D. annularis and M. merluccius were lower than the limit for biota in the district of Aliaga. Although the Target Hazard Quotient (THQ) values for Cd, Pb, Cu, Cr, Zn in all fish samples were lower than 1.0, the THQ for Hg levels were higher than 1.0 for most of the samples. According to the THQ values, M. merluccius may be consumed in moderation from Aliaga Bay, while the consumption of M. barbatus and P. erythrinus collected from Aliaga Bay are potentially hazardous to human health due to the Hg concentrations. Fish collected from Izmir Bay can be consumed safely.

The Omerli reservoir is located on the northeastern side of the Istanbul City. It is one of the most important sources of drinking water with a surface area of 23.1 km(2) and a volume of 220 x 10(6) m(3) in the Marmara Region. Water quality characteristics of the lake investigated from May 2002 to April 2003 enabled us to identify the effect of waste loads on water quality of Omerli Lake. The following parameters were measured in the lake water: temperature (16.1A degrees C), conductivity (250 mu S/cm), secchi disk depth (1.9 m), dissolved oxygen (DO) (9.36 mg/L), nutrients [ortho-phosphate (78.9 mu g/L), nitrate + nitrite (707.5 mu g/L) and ammonia-nitrogen (264 mu g/L)], chlorophyll a (9.43 mu g/L), total organic carbon (3.33 mg/L), total suspended solids (4.54 mg/L), total poly aromatic hydrocarbon (t-PAH) (0.69 mu g/L) and copper (24.5 mu g/L). T-PAH (16.5 mg/g-dry-w), Cu (96.5 mu g/g-dry-w), organic carbon (org-C) (2.0%) and N (0.44%) were determined in the surface sediment. The values of chlorophyll a and DO in the upper layer were relatively high and low secchi disk depths indicates eutrophic state. There are five channels discharging water, including waste water, into the lake. All channels were sampled during six occasions in order to cover variations between seasons. The following parameters were measured: total organic carbon, total phosphorus, total kjeldahl nitrogen, ammonia and total suspended solids with the flow rates. The GoA beyli stream has the highest flow into the lake (1.5 x 10(8) m(3)/year) but most of the nutrients were discharged from the Pa angstrom akoy channel. It is accounting for 81% of ammonia and 80% of total phosphorus into the lake. Three scenarios were run using AQUATOX model: (1) all existing inflows are discharging into the lake (present situation); (2) none is discharging; (3) all are discharging except the Pa angstrom akoy channel. The first scenario produced concentrations consistent with measurements in the lake. In all stations, a phytoplankton peak value was predicted during November and December 2002, and January 2003. In the second scenario, as expected, a significant decrease in the concentrations was predicted. In the third scenario, a small improvement in the water quality was obtained. To significantly improve the state of the lake, instead of entering Pa angstrom akoy channel, wastewater should bypass the lake.

Izmit Bay and its coastal environment was strongly affected by the August 17th, 1999 Izmit Earthquake. The changes in the Bay ecosystem and its chemical oceanography have been studied in detail previously [Okay, O.S., Tolun, L, Telli-Karakoç, F., Tüfekçi, V., Tüfekçi, H. And Morkoç, E. 2001. Ýzmit Bay ecosystem after Marmara earthquake and subsequent fire: The long-term data. Marine Pollution Bulletin 42, 361–369; Balkýs, N. 2003. The effect of Marmara (Izmit ) Earthquake on the chemical oceanography of Izmit Bay, Turkey. Marine Pollution Bulletin 46, 865–878.]. In this study surface sediments collected from the Izmit Bay before and after the earthquake have been analysed for total and individual (14 compounds) polycyclic aromatic hydrocarbons (PAH). Analyses have been performed by high performance liquid chromatography with fluorescence detection (HPLC/FD). Before the earthquake, total PAH concentrations in the Bay sediments ranged from 120 to 8900 ng/g while after the earthquake PAH concentrations varied between 240 and 11,400 ng/g. Molecular indices based on isomeric PAH ratios used to differentiate the pollution sources, clearly indicate the differences in molecular distribution of PAHs before and after the earthquake. Sediment data obtained before the earthquake shows that most of the contamination originated from high temperature pyrolytic inputs while after the earthquake it originated from petrogenic sources. This difference emphasises the environmental impact of uncontrolled discharges from petroleum industries after the earthquake. The LMW/HMW ratio (sum of the low molecular weight PAHs / the sum of higher molecular weight PAHs) predominance also changed after the earthquake as a result of the strong water movements. According to the characteristics of aromatic rings distributed in the bay sediments, the soluble parts of the total PAH were probably transferred to the water column after the earthquake as a result of resuspension process. The TEL/PEL (Threshold Effect Level / Probable Effect Level) analysis suggests that the Izmit Bay sediments were likely contaminated by acutely toxic PAH compounds. Keywords: Coastal waters, Surface sediments, Polycyclic aromatic hydrocarbons, Origin of PAHs, Toxicity, Earthquake

In this study, the complex wastewaters/effluents discharged to coastal regions of Turkey and Greece were sampled, and various toxicity tests were applied. The bioassays used included the assessment of the luminescence inhibition of the bacterium Vibrio fisheri, the photosynthesis inhibition (14C uptake rate) and growth inhibition of the algal species Phaeodactylum tricornutum, and the mortality of the crustacean Artemia franciscana and rotifer Brachionus plicatilis. Additionally, "neutral red retention" and "filtration rate" sublethal biomarker techniques were performed by utilizing the mussel species Mytilus galloproviancialis, inhabiting the points of discharges in Turkey. All discharges tested were found to be acutely toxic to P. tricornutum and slightly toxic to V. fisheri, A. franciscana, and B. plicatilis. Test results showed that the 14C uptake rate toxicity test was the most sensitive one among the other bioassays. The biomarker results showed that the health status of mussels in the coastal areas decreased significantly, indicating the pollution of the receiving waters in Turkey. The conclusions drawn highlight the necessity for an intesive ecotoxicological monitoring scheme that will incorporate the most suitable bioassays and biomarkers to adequately contribute to the upgrading and maintenance of the ecological quality of the coastal waters in Greece and in Turkey.

The aim of this study was to study ecological risk assessment of trace elements (As, Cd, Cr, Cu, Ni, Pb and Zn) in Izmit Bay surface sediments in the

Increasing marine traffic, over 55,000 ships visit per year, through the Turkish Straits System and the Sea of Marmara, produces a yearly average of 12 illegal oil discharges. This paper documents the comparison of chemical fingerprints of spilled oil with suspected sources of oils for identifying the source of illegal pollution in Turkey’s seas. Fingerprinting is initiated by comparison of the synchronous fluorescence spectra (Δ = 20 or 15 nm) of fugitive and suspected source oils. Potential matches of the spectra/chromatogram are confirmed or rejected by subsequent comparison of Fourier transform infrared spectrometry (FTIR), high-pressure liquid chromatography (HPLC) and gas chromatography with a flame ionisation detector (GC-FID) analysis results. In this study, 39 clean sea waters, 41 polluted sea waters and 111 suspected samples were analysed. According to the comparison of the suspected source sample and polluted sea water sample spectra by using spectrofluorometric analysis, 76 suspected source samples were categorised as non-match whilst 35 suspected samples were classified as match or probable match. Then, match and probable match samples were analysed by using further selected chromatographic methods. Finally, 28 suspected source samples were confirmed as a match, enabling legal proceedings to be initiated.

İzmit Bay is one of the most polluted and populated enclosed sea in Turkey. It has been the centre of industrial activities for the last 30 years. Seven major sources enter the bay waters along the north coastline of the bay. This investigation forms part of continuing ecotoxicology studies in the İzmit Bay designed to constrain and minimise the pollution caused by flourishing industry and a growing population. Sediments sampled from the mouths of the major discharges of İzmit Bay were analysed for their organic carbon, total polycyclic aromatic hydrocarbon (t-PAH) and trace inorganic element (Cd, Al, As, Pb, Hg and Cu) contents and compared with those found in the sediments from the reference station in the outer bay (in the Marmara Sea). The toxicity of sediments was determined in the bulk and elutriate samples by using algal (Phaeodactylum tricornutum) batch bioassays. Chemical data showed that the sediments collected from the inner sites of the bay have been contaminated with Cd, Hg, As and PAHs. Organic carbon contents were also found higher. All the major industrial discharges into the bay are now biologically treated but bioassays performed with bulk sediments revealed that the recent sediments are toxic to the microalgae throughout the bay. The results are consistent with the previous toxicity studies performed with the industrial discharges. Keywords: Organic carbon, PAHs, Metals, Sediment toxicity

Countries surrounding the Mediterranean Sea and Black Sea signed the Barcelona Convention (1976) and Bucharest Convention (1992) respectively and Turkey is the one of the contracting parties for both of them. In this content, they formed the “Mediterranean Action Plan (MAP)” and “Black Sea Environment Programme” to control water pollution in the Mediterranean and Black Sea, respectively. To achieve this goal, each region formed their Land Based Sources Strategic Action Programme (LBS SAP) in the second part of the 1990s within the framework of the Land Based Sources Protocols (LBS Protocol) which are sub protocols of the Barcelona Convention and Bucharest Convention. These programmes define the major land based environmental problems and proposed solutions to the problems and set the deadlines to perform the necessary tasks. In the line with LBS SAP’s, Mediterranean countries have been already developed their “National Action Plan’s for Land Based Sources (LBS NAP) in 2005.

On 17 August 1999 a powerful earthquake struck the eastern part of Marmara Region and Izmit Bay, the most industrialized and populated area of the region. Environmental effects of the earthquake and subsequent refinery fire were partly investigated by several scientists (Okay et al., 2001, 2003; Tolun et al., 2001, 2006; Balkis, 2003; Unlu and Alpar, 2004; Karakas and Pekey, 2005). As a part of the previous efforts, in this study, the levels of total PCBs, sum of the marker PCBs and TEqs in mussels collected immediately after and 1 year later the earthquake were presented. Total PCB (# 1-209) levels in mussels from different coastal locations were found between 5.47 and 14 ng/g in September 1999 and between 11.2 and 36.0 ng/g in June 2000. June 2000 samples from throughout the Bay contained higher quantities of total, marker PCBs and TEq values when compared with the before earthquake values. The elevated concentrations of PCBs in mussels collected after the earthquake implies an input of PCBs to the water column form different sources such as underlying sediments and/or land-based sources such as industrial inputs. Although WHO-TEq values found in this study for Izmit Bay (0.4 +/- 0.1 - 1.4 +/- 0.7 pg/g) are lower than the proposed values for fisheries products (4 pg/g) by EC Regulation 199/2006, considering the TDI value as 2 pg WHO-TEq/kg bw (COT, 2001) it was concluded that consumable mussels from Izmit Bay pose a risk for health.

The Izmit Bay is an elongated semi-enclosed bay in the Marmara Sea. It is being increasingly polluted by both domestic and industrial waste discharge since 1970’ s. A monitoring program was conducted between 1999-2000 to document the state of pollution in the bay. This includes the effect of Marmara (Izmit) earthquake (magnitude 7.4) that occurred in August 1999. A stable two-layer ecosystem exists in the bay throughout the year due to continuous inflow of the saltier Mediterranean and brackish Black Sea water to the Marmara basin. Therefore, the principal biochemical characteristics of the bay are governed by the two-layer flow system over the basin. Dissolved oxygen (DO) is generally at a saturated levels in the surface layer which is 10 to 15 m thick, but it is depleted to 60– 70 µ M in the lower layer, exhibiting a steep gradient in the sharp halocline. When the earthquake occurred, great loads of industrial wastes were released into the bay surface waters, which enhanced primary production in the upper layer and thus large export of particulate organic matter to lower layer and eventually to the bottom. Accordingly, DO was consumed and anoxic condition was established even in the upper layer/halocline interface, the halocline and bottom waters of the eastern and central bay. In this period, concurrent increases were observed in phosphate and ammonia contents at the halocline and in deep water whilst the nitrate was almost consumed via denitrification processes in the anoxic water. Recently, the industrial C, N and P loads increased by as much as 8 fold within five years (1995– 2000) whilst domestic inputs increased by 50%. Total organic matter discharged to the bay increased more than double within the last 15 years. Besides, most factories in the region release toxic wastes into the bay after only partial treatment.

Earthquake scarps associated with recent historical events have been found on the floor of the Sea of Marmara, along the North Anatolian Fault (NAF). The MARMARASCARPS cruise using an unmanned submersible (ROV) provides direct observations to study the fine-scale morphology and geology of those scarps, their distribution, and geometry. The observations are consistent with the diversity of fault mechanisms and the fault segmentation within the north Marmara extensional step-over, between the strike-slip Ganos and Izmit faults. Smaller strike-slip segments and pull-apart basins alternate within the main step-over, commonly combining strike-slip and extension. Rapid sedimentation rates of 1?3 mm/yr appear to compete with normal faulting components of up to 6 mm/yr at the pull-apart margins. In spite of the fast sedimentation rates the submarine scarps are preserved and accumulate relief. Sets of youthful earthquake scarps extend offshore from the Ganos and Izmit faults on land into the Sea of Marmara. Our observations suggest that they correspond to the submarine ruptures of the 1999 Izmit (Mw 7.4) and the 1912 Ganos (Ms 7.4) earthquakes. While the 1999 rupture ends at the immediate eastern entrance of the extensional Cinarcik Basin, the 1912 rupture appears to have crossed the Ganos restraining bend into the Sea of Marmara floor for 60 km with a right-lateral slip of 5 m, ending in the Central Basin step-over. From the Gulf of Saros to Marmara the total 1912 rupture length is probably about 140 km, not 50 km as previously thought. The direct observations of submarine scarps in Marmara are critical to defining barriers that have arrested past earthquakes as well as defining a possible segmentation of the contemporary state of loading. Incorporating the submarine scarp evidence modifies substantially our understanding of the current state of loading along the NAF next to Istanbul. Coulomb stress modeling shows a zone of maximum loading with at least 4?5 m of slip deficit encompassing the strike-slip segment 70 km long between the Cinarcik and Central Basins. That segment alone would be capable of generating a large-magnitude earthquake (Mw 7.2). Other segments in Marmara appear less loaded.

The toxicity of the polyaromatic hydrocarbon pyrene to Mytilus edulis and Mytilus galloprovincialis was investigated in experiments conducted in the United Kingdom for M. edulis and in Turkey for M. galloprovincialis. Experimental conditions of temperature and salinity were chosen to be appropriate to the ambient conditions in which the mussels typically live. The effect of different feeding regimes on pyrene bioaccumulation and toxicity was also investigated. Feeding rate and neutral red retention biomarker techniques were used for toxicity assessment. An experiment with M. edulis demonstrated that mussels exposed to pyrene accumulated increasing amounts of this compound throughout a 15-day exposure period and that accumulation increased in relation to exposure concentration and with increasing concentration of unicellular algal food material. However, in these experiments, which were protected from UV light, there was no clear relationship between pyrene concentration in tissues and feeding rate. A clear concentration–response relationship was observed between tissue concentration and neutral red retention for days 1 and 7 of the experiment, but this relationship was lost by day 15, with evidence of the cells recovering. A similar experiment was conducted with M. galloprovincialis at a single (high) pyrene concentration in darkness. The feeding rate of the exposed mussels was always lower than the feeding rate of the control mussels, although the difference was insignificant at 7-day exposure. A decreasing trend in health status of the mussels was indicated by the neutral red retention assay results after 7 and 15 days of exposure to pyrene. In a third experiment (with M. galloprovincialis), an illuminated algal chemostat system containing pyrene was inserted in the exposure system as the food source for the mussels. Both biomarker results showed conclusively that toxic effects correlated with pyrene bioaccumulation, though there was no clear evidence for light-enhanced toxicity. These experiments showed that experimental conditions such as salinity, temperature and feeding regime and perhaps the species of mussel used may influence whether pyrene is perceived as being a toxic molecule. Keywords: Bioaccumulation, Effect, Pyrene, Mussels, Biomarker, Filtering rate, Lysosome

As is well known, a powerful earthquake along the North Anatolian Fault struck the eastern part of the Marmara region on August 17, 1999. İzmit Bay, which is known as one of the most polluted sites of Turkey, was also affected by the quake and the subsequent refinery fire.The measurements performed just before and after the earthquake showed that T-PAH levels increased significantly after the event [Okay OS, Tolun L, Telli-Karakoç F, Tüfekçi V, Tüfekçi H, Morkoç E. İzmit Bay (Turkey) ecosystem after Marmara earthquake and subsequent refinery fire: the long-term data. Marine Pollution Bulletin 2001;42:361–9]. In the framework of ecotoxicological studies, the Bay ecosystem was continuously monitored for T-PAH levels in seawater, sediments and mussels (Mytilus galloprovincialis) to find out whether change occurred during the 2-year period following the earthquake. For that purpose, after the earthquake, the samples were collected six times between the period of September 1999 and March 2001 at coastal stations of the Bay situated away from the mouth of main discharges.The responses of the mussels were also measured by means of the lysosomal stability of the blood cells and feeding rate biomarker techniques at two different sites of the bay.Although the T-PAH levels in all matrices generally showed a decreasing trend, they were found to be still high especially at stations near the refinery. Both biomarker results showed that the health status of the mussels is very poor in the Bay ecosystem, based on the results obtained from the two sites monitored. Keywords: Polycyclic aromatic hydrocarbons, Sediments, Mussels, Effects of earthquake, Biomarkers

In 1999, the concentrations of 16 polycyclic aromatic hydrocarbons (PAHs), the total PAH and polychlorinated biphenyls (PCBs) were measured in sea water, sediment and mussels collected along the coast of Izmit Bay, the most important bay of the Marmara Sea. The total-PAH concentrations, measured by Spectrofluorometry were in the range of 1.16-13.68 microg/l in sea water, in the range of 30.0 1670.0 microg/g dry weight in sediments and in the range from 5.67 to 14.81 microg/g wet weight in edible part of mussel. HPLC revealed Phenanthrene (three rings), chrysene (four rings) and benz[a]antracene (five rings) to be the dominant PAHs in sea water, while 16 different PAHs compounds were observed and measured in mussel samples. The most pollution occured at Dogu Kanali and Dil Deresi where were the main rivers containing wastes fall into the the Izmit Bay. Although the maximum mono-ortho PCB concentrations in sea water were measured in the Dil Deresi River (26.33 ng/l) and the Solventas (22.19 ng/l) stations, maximum PCB concentrations in mussels were measured in the SEKA (28.11 microg/kg) and the Dil Deresi River (25.68 microg/kg). The dominant congeners of PCBs were from tetra to hexachlorobiphenyls. The toxicity equivalent values were very low in sea water and mussels.

As a part of Marmara Sea, Izmit Bay (Turkey) has been one of the most polluted sites in the region for the last 25 years. On 17 August 1999, a powerful earthquake along the North Anatolian Fault struck the eastern part of the Marmara region including Izmit Bay. The earthquake destroyed many coastal cities. The Bay was also affected by the quake and subsequent fire in the refinery situated on the north-eastern coast of the Bay. Oceanographic characteristics and polycyclic aromatic hydrocarbon (PAH) levels of Izmit Bay (Marmara Sea) have been investigated to find out the degree of contamination. Seawater samples were collected at nine stations of the Bay in April and September 1999 and the results were compared with those obtained in the previous years (1984 and 1994). Monitoring data are presented for plant nutrients (nitrate + nitrate, ortho-phosphate and silicate), dissolved oxygen and chlorophyll a. Surface sediments and mussels, Mytilus galloprovincialis, have been analysed for total PAH (T-PAH) contents in April and September 1999 (before and after the Marmara Earthquake) for the samples collected from eight coastal stations of the Bay. Biomarker (Lysosomal stability and feeding rate) studies at three different sites of the Bay have also been performed to investigate the effect of pollution on mussels. Nitrate + nitrite levels in the upper layer of the eastern part of the Bay increased significantly compared to those measured before the earthquake. Of the samples analysed, the highest o-phosphate concentrations were found in September 1999 in the bottom waters of the Bay. The concentration of chlorophyll a reached its minimum value of the last 15 years. Dissolved oxygen decreased dramatically from 1984 to 1999. Total PAH concentrations measured in April 1999 at both offshore and coastal sites of the Bay were more or less the same (2 micrograms l-1). The subsequent fire after the earthquake caused an increase in the total PAH levels in water column, in sediment and in mussels. Seawater total PAH concentrations ranged between 3.5 and 11 micrograms l-1 at open coast stations and 5-17.5 micrograms l-1 at coastal stations in September 1999. A 2- to 3-fold increase in sediment PAH concentrations (200-5220 mg kg-1 dry weight) was detected after the earthquake. This increase was much more significant in the sediments located around the refinery. More contaminated mussels were detected around the refinery area (110-170 mg kg-1 dry weight). Overall, sediment and mussel PAH concentrations in Izmit Bay are much higher than those found in the other marine systems. In general, the feeding rate and the neutral red retention times of the mussels decreased in some sites of the Bay after the earthquake, but no direct correlation could be detected between the body burden of mussels and biomarkers or between the two biomarker techniques.

The elongated semi-enclosed Bay of İzmit, which receives both domestic and industrial wastes, has been monitored by measuring its physical and biochemical parameters for 2 years, 1994–1995. It is clear that there are two distinct water masses. The upper layer has been occupied by the less saline (22–26 ppt) waters of the Black Sea origin; whereas the lower layer contains saline (38.5 ppt) Mediterranean waters. The seasonal variations in the biochemical characteristics were dependent on the bay's two-layer flow system. If one considers the distribution of transparency in the upper bay waters, it has been observed that the Secchi disk depth (SDD) decreases from west to east. Furthermore, these depths are limited by the high primary productivity associated with the low concentrations of nutrients observed during the spring. Discharges of wastes into the surface waters significantly affect the biological production and oxygen consumption in the lower layer. Within the last 10 years, 80% of organic matter has been removed from industrial wastewater. However, organic loads from the domestic wastewaters have doubled because of the growth in the surrounding population. Fortunately, as a result, the total organic loads in the bay have not changed significantly within the last 10 years. Keywords: İzmit Bay, Nutrient, Transparency, Waste loads, Chlorophyll-a