Stretchable silk fibroin hydrogels.

Hydrogels derived from silk fibroin (SF) are attractive soft materials in biomedical applications such as drug delivery and tissue engineering. However, SF hydrogels reported so far are generally brittle in tension limiting their load-bearing applications. We present here a novel strategy for preparing stretchable SF hydrogels by incorporating flexible polymer chains into the brittle SF network, which strengthen the interconnections between SF globules. We included N, N-dimethylacrylamide (DMAA) monomer and ammonium persulfate initiator into an aqueous SF solution containing a diepoxide cross-linker to in situ generate flexible poly (N,N-dimethylacrylamide) (PDMAA) chains. Moreover, instead of SF, methacrylated SF was used for the gel preparation to create an interconnected SF/PDMAA network. The free-radical polymerization of DMAA leads to the formation of PDMAA chains interconnecting globular SF molecules via their pendant vinyl groups. Incorporation of 2 w/v% DMAA into the SF network turns the brittle hydrogel into a stretchable one sustaining up to 370% elongation ratio. The mechanical properties of SF hydrogels could be adjusted by the amount of PDMAA incorporated into the SF network. The stretchable and tough SF hydrogels thus developed are suitable as a scaffold in tissue engineering and offer an advantage as a biomaterial over other SF-based biomaterials.

Numerical evaluation of bioaccumulation and depuration kinetics of PAHs in Mytilus galloprovincialis.

Polycyclic aromatic hydrocarbons (PAHs) are important organic pollutants in the aquatic environment due to their persistence and bioaccumulation potential both in organisms and in sediments. Benzo(a)anthracene (BaA) and phenanthrene (PHE), which are in the priority pollutant list of the U.S. EPA (Environmental Protection Agency), are selected as model compounds of the present study. Bioaccumulation and depuration experiments with local Mediterranean mussel species, Mytilus galloprovincialis were used as the basis of the study. Mussels were selected as bioindicator organisms due to their broad geographic distribution, immobility and low enzyme activity. Bioaccumulation and depuration kinetics of selected PAHs in Mytilus galloprovincialis were described using first order kinetic equations in a three compartment model. The compartments were defined as: (1) biota (mussel), (2) surrounding environment (seawater), and (3) algae (Phaeodactylum tricornutum) as food source of the mussels. Experimental study had been performed for three different concentrations. Middle concentration of the experimental data was used as the model input in order to represent other high and low concentrations of selected PAHs. Correlations of the experiment and model data revealed that they are in good agreement. Accumulation and depuration trend of PAHs in mussels regarding also the durations can be estimated effectively with the present study. Thus, this study can be evaluated as a supportive tool for risk assessment in addition to monitoring studies.

Performance of anaerobic sequencing batch reactor in the treatment of pharmaceutical wastewater containing erythromycin and sulfamethoxazole mixture.

This study evaluates the joint effects of erythromycin-sulfamethoxazole (ES) combinations on anaerobic treatment efficiency and the potential for antibiotic degradation during anaerobic sequencing batch reactor operation. The experiments involved two identical anaerobic sequencing batch reactors. One reactor, as control unit, was fed with synthetic wastewater while the other reactor (ES) was fed with a synthetic substrate mixture including ES antibiotic combinations. The influence of ES antibiotic mixtures on chemical oxygen demand (COD) removal, volatile fatty acid production, antibiotic degradation, biogas production, and composition were investigated. The influent antibiotic concentration was gradually increased over 10 stages, until the metabolic collapse of the reactors, which occurred at 360 days for the ES reactor. The results suggest that substrate/COD utilization and biogas/methane generation affect performance of the anaerobic reactors at higher concentration. In addition, an average of 40% erythromycin and 37% sulfamethoxazole reduction was achieved in the ES reactor. These results indicated that these antibiotics were partly biodegradable in the anaerobic reactor system.

Micro-organic pollutants and biological response of mussels in marinas and ship building/breaking yards in Turkey.

Concentrations of PAHs, PCBs and OCPs in sediments and mussels (caged and/or native) were determined at 16 stations in six major sites of coastal Turkey. The biological effects of pollution were evaluated using sediment toxicity tests and enzyme activity assays. EROD, PROD, GST, AChE, CaE, and GR activities were evaluated using the digestive glands of mussels. The total PAH concentrations in the sediments varied between nd and 79,674 ng g(-1) dw, while the total OCP concentrations were in the range of nd to 53.7 ng g(-1) dw. The total PAH concentrations in mussels varied between 22.3 and 37.4 ng g(-1) ww. The average concentrations of total PCBs in mussels were 2795 pg g(-1) ww in the shipyard, 797 pg g(-1) ww in Marina 2 and 53 pg g(-1) ww in Marina 1 stations. The results of whole-sediment toxicity tests showed a strong correlation between toxicity test results and pollutant concentrations. Selected cytosolic enzyme activities in digestive glands differed significantly depending on localities. These differences in enzyme activities were mainly related to the different pollutant levels of the sampling sites. The micro-organic contaminant profile patterns, toxicity tests and biomarker studies showed that shipyards and shipbreaking yards are the major potential sources of organic pollution in coastal areas.

Use of passive samplers in pollution monitoring: a numerical approach for marinas.

Triolein-containing semipermeable membrane devices (SPMDs) and butyl rubber (BR) based sorbents were employed as passive samplers in 14 coastal stations of Turkey including shipyards and marinas to characterize time-integrated levels of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) and their relationship to potential pollution sources. Passive samplers of SPMDs and BR sorbents were deployed for 30days in the spring of 2012. The maximum concentrations of total PAH and PCB compounds sequestered by SPMDs were 3338 ng g(-1) SPMD and 4247 pg g(-1) SPMD. (END)-I and DDT-related compounds were dominant OCP compounds for most of the sites in passive samplers. Total PAH concentrations in SPMDs were found 1.2 to 8 times higher than the concentrations in BRs. However, BR sorbents were able to sample some PAHs which could not be sampled by SPMDs. The concentrations of PCBs and OCPs in BRs were similar or higher than SPMDs. SPMD-data were used to estimate the average ambient water concentrations of the contaminants. Two existing theoretical approaches have been used to derive the concentrations of hydrophobic pollutants in the ambient waters. The results were found very similar and range from 7318 to 183864 pg L(-1) for PAHs, from 2 to 186 pg L(-1) for PCBs, and from 98 to 848 pg L(-1) for OCPs. Furthermore, a simple numerical model was designed to estimate the boat-related water concentrations in marinas by using the seawater data supplied by SPMDs. The model was mainly built on the water concentration and the capacities of a particular marina and then applied to two sites in the second marina. A good correlation was found between the model outputs and SPMD-water data.

Water concentrations of PAH, PCB and OCP by using semipermeable membrane devices and sediments.

Water concentrations of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were estimated from semipermeable membrane devices (SPMDs) and from sediment pollutant concentrations. SPMDs were deployed in the Istanbul Strait and Marmara Sea and retrieved after 7 and 21 days. Performance reference compounds (PRCs) were used to determine the site-specific sampling rates of the compounds. Water concentrations (C(w)) of the analyzed compounds estimated by using two different calculation methods for SPMDs were found similar. C(w) of total PAHs estimated from SPMDs (C(w-spmd)) were found between 13 and 79 ng L⁻¹ and between 7.0 and 68 ng L⁻¹ for 7 and 21 days of deployments respectively. Water concentrations of PCBs using sediment data was found as between 0.001 and 11.0 ng L⁻¹. The highest value of C(w-spmd) for two deployments were 2.8 ng L⁻¹ for OCPs. C(w) estimated from sediment concentrations were generally higher than those estimated from SPMDs.

Efficiency of butyl rubber sorbent to remove the PAH toxicity.

Large amounts of polycyclic aromatic hydrocarbons (PAHs) have been released to the marine environment as a result of oil spills and from other sources including wastewaters, surface runoff, industrial processes, atmospheric deposition, biosynthesis, and natural events such as forest fires. PAHs have been known to affect a variety of biological processes and can be potent cell mutagens/carcinogens and toxic. In this study, PAH toxicity removal was investigated by using a novel macroporous butyl rubber (BR) sorbent. To find out the toxicity removal efficiency of the sorbents, the toxicity tests with Vibrio fisheri (luminescence bacteria) and Phaeodactylum tricornutum (marine algae) were applied to the acenaphthene (Ace) and phenanthrene (Phen) solutions in seawater (Ace: 500- 1000 µg/L; Phen; 100-1000 µg/L) before and after sorbent applications. Additionally, lysosomal stability and filtration rate biomarker techniques were applied to the mussels (Mytilus galloprovincialis) exposed to 1000 µg/L Phen solution and bioaccumulation was measured. The results showed that the toxicity of the PAH solutions decreased 50-100 percent depending on the concentration of the solutions and organisms. Phaeodactylum was found as the most sensitive organism to Phen and Ace. Since the application of BR sorbent removed the Phen from the solution, the bioaccumulated Phen amount in the mussels decreased accordingly.

Bioaccumulation depuration kinetics and effects of benzo(a)anthracene on Mytilus galloprovincialis.

Polycyclic aromatic hydrocarbons (PAHs) are important environmental pollutants due to their persistence and bioaccumulation potential both in organisms and in sediments. In this study, bioaccumulation and depuration experiments were performed employing local Mediterranean mussel species, Mytilus galloprovincialis, with two biomarkers: filtration rate and lysosomal stability (neutral red retention) assay. Benzo(a)anthracene (BaA) was chosen as the model PAH compound due to its common presence in several matrices in the marine environment. Bioconcentration Factors (BCFs) for the mussels exposed to different BaA concentrations were calculated from both kinetic rate constants and from the experimental data and found between 27-3184 and 16-2745, respectively. Experimental QSAR values were found comparable to the previous QSAR models created for BaA. The effect of BaA exposure on the mussels showed a more clear dose-response relationship according to the results of lysosomal stability compared to the filtration rate.

Comparison of unilateral hemilaminotomy and bilateral hemilaminotomy according to dural sac area in lumbar spinal stenosis.

INTRODUCTION: Unilateral hemilaminotomy (ULH) and/or bilateral hemilaminotomy (BLH) with limited facetectomy are defined approaches to decompress the thecal sac and exiting lumbar nerve roots without increasing the risk of subsequent spinal instability. METHODS: We retrospectively analyzed 18 cases with degenerative lumbar spinal stenosis (LSS) with BLH or ULH that was performed in 11 and 7 cases, respectively. Magnetic resonance imaging (MRI) was performed at the follow-up examination and dural sac area (DSA) was calculated on T(2)-weighted MRI images and then compared statistically. In addition, the economic and functional status of the patients were evaluated with the Prolo scale. RESULTS: The mean preoperative values on the visual analogue scale (VAS) were 7.1 for lumbalgia and 7.0 for leg pain, respectively. These values were calculated as 4.8 and 4.4 at the follow-up, respectively. The VAS was significantly improved after operation compared to preoperative values (p=0.001). The mean value of the DSA was 84 (+/-32) mm(2) before the operation and 126 (+/-35) mm(2) at the follow-up and the comparison was statistically significant (p=0.001). No statistical correlation was found between VAS and DSA or between VAS and ULH-BLH groups, however, DSA of the BLH cases was significantly higher than in the ULH group (p=0.035). There was a significant negative correlation between VAS scores (back and leg pain) and Prolo status. However, there was no significant difference between DSA and Prolo scores, and between ULH or BLH groups in terms of Prolo scores. CONCLUSION: A unilateral approach with bilateral decompression and bilateral approach with bilateral hemilaminotomy are both minimal invasive, adequate and safe approaches with excellent prognosis. However, BLH leads to a bigger expansion of DSA.

Orbitocerebral injury by a knife: case report.

Orbital penetrating injuries may cause significant harm to the optic nerves and eyeball as well as to the brain and cerebral vessels. Management of orbital foreign bodies should include prompt recognition of the extent of the injury, broad-spectrum parenteral antibiotics, tetanus prophylaxis, anticonvulsant medication and early surgical intervention under direct vision to remove the foreign body and to avoid immediate and long-term complications. We report a penetrating orbital injury caused by a bread knife that extended from the orbit to the tegmental dura mater of the temporal bone. The knife's main trajectory coursed through the temporal lobe. Adjacent cerebral structures were explored before removal of the knife.

Orbitocerebral injury by a knife: case report

Orbital penetrating injuries may cause significantharm to the optic nerves and eyeball as well as to thebrain and cerebral vessels. Management of orbitalforeign bodies should include prompt recognition of theextent of the injury, broad-spectrum parenteral antibiotics,tetanus prophylaxis, anticonvulsant medicationand early surgical intervention under direct vision toremove the foreign body and to avoid immediate andlong-term complications. We report a penetrating orbitalinjury caused by a bread knife that extended fromthe orbit to the tegmental dura mater of the temporalbone. The knife’s main trajectory coursed through thetemporal lobe. Adjacent cerebral structures were exploredbefore removal of the knife (AU)

Los traumatismos perforantes orbitarios suelencausar un daño importante al nervio óptico y globoocular, así como al cerebro y vasos cerebrales. Laórbita permite un acceso fácil hacia la cavidad cranealdebido a que tiene una pared ósea delgada y a la presenciadel agujero óptico. El enfoque terapéutico de lostraumatismos orbitarios por cuerpo extraño dependefundamentalmente del tipo de traumatismo y delcuerpo extraño. El tratamiento de este tipo de lesionesincluirá un rápido diagnostico de la magnitud del dañoocasionado, el empleo por vía parenteral de antibióticosde amplio espectro, profilaxis del tétanos, medicaciónanticonvulsivante y cirugía urgente que permita, bajovisión directa, la extracción del cuerpo extraño, a fin de evitar complicaciones inmediatas o a largo plazo. Presentamosel caso de un traumatismo perforante ocularocasionado por un cuchillo de pan que se extendíadesde la órbita hasta el tegmentum del hueso temporal.El cuchillo seguía una trayectoria directa a través dellóbulo temporal. Se practicó una exploración quirúrgicade las estructuras cerebrales adyacentes para poderextirpar el cuchillo. Se revisan y analizan las opcionesde tratamiento de los traumatismos perforantes de laórbita (AU)

Neuroprotective effect of melatonin on experimental peripheral nerve injury: an electron microscopic and biochemical study.

BACKGROUND AND STUDY AIMS: Melatonin is an important antioxidant agent with a protective role in the prevention of oxidative stress. We designed an experimental study which focused on the potential neuroprotective effect of melatonin on peripheral nerve injury. MATERIALS AND METHODS: Sciatic nerve injury was induced in the mid thigh region of 30 male Wistar rats by clip compression. Melantonin was injected intraperitoneally in 15 of the 30 rats. Electron microscope and biochemical studies were performed to assess the potential beneficial effect of melatonin on peripheral nerve regeneration. Changes to cellular organelles, myelin lamellae and axons were studied. RESULTS: There was a significant difference between the melatonin and nerve injury groups. Rats treated with melatonin demonstrated significant structural protection of the myelin lamellae compared to the nerve injury group. Axonal shrinkage and myelin changes were not prominent histopathologically in melatonin-treated group. Biochemical analysis confirmed the neuroprotective effects of melatonin with significantly lower lipid peroxidation and myeloperoxidase activity measurements in the melatonin-treated group compared to the neural injury group. The results indicate that melatonin can improve neural healing. CONCLUSION: With its neuroprotective effect, as demonstrated in this experimental peripheral nerve injury, melatonin might be used successfully in clinical practice. Further studies on the correct dosage and possible side effects are necessary.

Lumbar epidural abscess caused by brucella species: report of two cases.

Spinal epidural abscess due to Brucella species is usually associated with spondylodiscitis. Urgent surgical decompression should be performed in cases with moderate to severe neurological deficits particularly if progressive. We report clinical features of two cases operated for lumbar epidural abscess caused by Brucella species. Early surgical decompression combined with medical treatment could decrease progression of neurological findings or the severity of complications. Iatrogenic dural tear at the operation should be repaired immediately with fine sutures and fibrin tissue glue to prevent further innoculation into the cerebrospinal axis. These cases should be cautiously followed for any recurrence or neurobrucellosis.

PCB and PCDD/F in sediments and mussels of the Istanbul strait (Turkey).

Sediment and mussel samples collected along the coasts of the Istanbul strait and an island in Marmara Sea (Turkey) were analyzed for six indicator polychlorinated biphenyl (PCB), 12 dioxin-like PCB (dl-PCB) and 17 polychlorinated dibenzo-p-dioxin/furan (PCDD/F) congeners. Samples contained different concentrations of PCBs and among these, congeners 153, 75, 105 and 118 in sediments and congeners 153, 138 and 118 in mussels were most abundant. The concentration levels of total PCBs and PCDD/Fs in sediments ranged from 17.9 to 539746 pg g(-1)dm and 2.04 to 60.5 pg g(-1)dm, respectively. The total WHO-TEQ values ranged between 0.01 and 17.8 pg g(-1)dm in sediments, and 0.98 and 1.01 pg g(-1)ww in mussels. None of the sediment and mussel samples analyzed exceeded the limits suggested in the sediment quality guideline and safe values set by the European Community for seafood intended for human consumption, respectively.

Lumbar epidural abscess caused by brucella species: report of two cases

Spinal epidural abscess due to Brucella species isusually associated with spondylodiscitis. Urgent surgicaldecompression should be performed in cases withmoderate to severe neurological deficits particularlyif progressive. We report clinical features of two casesoperated for lumbar epidural abscess caused by Brucellaspecies. Early surgical decompression combinedwith medical treatment could decrease progression ofneurological findings or the severity of complications.Iatrogenic dural tear at the operation should be repairedimmediately with fine sutures and fibrin tissue glueto prevent further innoculation into the cerebrospinalaxis. These cases should be cautiously followed for anyrecurrence or neurobrucellosis (AU)

Los abscesos epidurales espinales debidos a Brucellase asocian habitualmente a espondilodiscitis. Ladescompresión quirúrgica urgente debe ser realizadaen casos con déficit neurológico moderado o graveparticularmente si este es progresivo. Describimos losaspectos clínicos de dos casos operados por abscesosepidurales causados por Brucella. El tratamiento quirúrgicotemprano asociado con tratamiento médicopuede disminuir la progresión de la sintomatologíaneurológica y la gravedad de las complicaciones. Laaparición de desgarros durales durante la cirugía debeser reparada de forma inmediata con sutura o pegamentosde fibrina para prevenir la inoculación dentrodel neuroeje. Estos casos deben ser seguidos de formacuidadosa para evitar la recurrencia de la neurobrucelosis (AU)

Polycyclic aromatic hydrocarbons and effects on marine organisms in the Istanbul Strait.

Surficial sediments and mussels (Mytilus galloprovincialis) from the Istanbul Strait and Marmara Sea were analysed for sixteen parent polycyclic aromatic hydrocarbon (PAH) contents by gas chromatography-mass spectrometry (GC-MS) employing isotope dilution technique. Microalgae toxicity testing was applied to sediment elutriates and biological responses in terms of filtration rate and lysosomal stability were measured in mussels. Total PAH concentrations ranged from 2.1 to 3152 ng g(-1) dry wt in sediments and from 43-601 ng g(-1) wet weight in mussels. Molecular indices of phenanthrene/ anthracene, fluoranthene/pyrene and benzo(a)anthracene/chrysene were used to differentiate between pyrolytic and petroleum origin. Results showed that most of the contamination originates from high temperature pyrolytic inputs with some slight contribution of petrogenic PAH. PAH in sediments were frequently lower than the National Oceanic and Atmospheric Administration (NOAA)-ERM (Effects Range Medium) index. Results of sediment elutriate toxicity testing and biomarkers indicate that the cause of negative effects in sediments may result from different classes of pollutants and does not only relate with PAH contamination. Mussels from most of the stations showed both reduced lysosomal membrane stability and filtration rate indicating disturbed health although the two biomarker results did not always complement each other. The effect studies showed that the pollutants in the strait ecosystem have more pronounced effects in the middle parts than those at the Black Sea entrance.

Ozonation of synthetic versus natural textile tannins: recalcitrance and toxicity towards Phaeodactylum tricornutum.

A sound in-plant pollution control strategy can only be defined by paying due attention to bio-recalcitrance and toxicity. In this context the levels of toxicity and inert COD introduced to textile dyebath discharges by two alternative auxiliary chemicals, namely natural tannin (NT) and synthetic tannin (ST), were investigated. The effect of 40 minutes ozonation at 1,000 mg h(-1) at pH 3.5 on the segregated effluent streams containing the above-mentioned tannin formulations was evaluated in terms of changes in toxicity and recalcitrance. The effect of ozonation on the COD distribution of raw and ozonated NT and ST samples according to their molecular weight cut-offs was also assessed. Both untreated tannin formulations exerted high acute toxicity towards marine microalgae Phaeodactylum tricornutum. Moderate decrease in the toxicity levels of both tannins was observed upon ozonation. The raw NT formulation with a COD content more than twice that of its alternative raw ST had an initially inert soluble COD content of only 25 mg/L, while the initially inert COD was 135 mg/L for ST. As the initially inert soluble COD content of NT was considerably lower, this textile auxiliary did not need chemical pretreatment to improve its biodegradability. On the other hand, the initially inert soluble COD content of ST was reduced by 70% by ozone pretreatment. In terms of residual COD contents achievable after passing through a biological treatment system, raw NT and pretreated ST formulations yielded 100 and 95 mg/L COD, respectively. The highest proportion of COD (46% for NT and 88% for ST) was found in the <1 kDa range. The same fraction increased to 93% for NT after ozonation, while for ST no significant change was observed in the COD distribution of the molecular weight cut-offs after ozonation.

Treatability of cefazolin antibiotic formulation effluent with O3 and O3/H2O2 processes.

The effect of applying ozonation and perozonation to antibiotic cefazolin-Na formulation effluents were investigated in this study. Twenty minutes of ozonation at a rate of 1,500 mg/L-h was observed to remove COD by 38%, whereas a COD removal efficiency of 40% was achieved via H2O2 enhanced ozonation (same conditions + 31.25 mM H2O2). Both of the pretreatment alternatives were monitored to elevate the BOD5/COD ratio from 0.01 to 0.08. The initially inert COD was reduced by 38% using ozonation and by 60% employing H2O2 enhanced ozonation. In terms of the lowest achievable effluent COD levels after bio-treatment, ozonation was observed to yield a residual COD of 205 mgL(-1), while a residual COD of 135 mgL(-1) was involved for perozonation. According to the results of acute toxicity on Phaedactylum tricornutum, ozonated and perozonated samples exhibited more toxicity than the untreated effluent after 4 days. The activated sludge inhibition test demonstrated that both of the pretreatment alternatives efficiently eliminated the inhibition of investigated formulation effluent.

Effect of chemical treatment on the acute toxicity of two commercial textile dye carriers.

In the present experimental study, the effect of chemical treatment (coagulation-flocculation) on the acute toxicity exerted by two commercial dye carriers (called Carrier A and B herein) often used in the textile industry was investigated. Two different test organisms were selected to elucidate the situations in activated sludge treatment systems (activated sludge microorganisms) as well as in receiving water bodies (ultimate marine discharge). According to the results of a comprehensive analysis covering COD removal efficiencies, sludge settling characteristics and operating costs involved in coagulation-flocculation, the optimum treatment conditions were defined as follows; application of 750 mg/L ferrous sulphate at a pH of 9.0 for Carrier A; and application of 550 mg/L ferrous sulphate at a pH of 9.0 for Carrier B. The acute toxicities of both dye carriers towards marine microalgea Phaeodactylum tricornutum could be reduced significantly after being subjected to coagulation-flocculation. Fair toxicity removals (towards heterotrophic mixed bacterial culture accommodated in activated sludge treatment) were obtained with coagulation-flocculation for both of the carriers under investigation.

Polycyclic aromatic hydrocarbon contamination in coastal sediments of the Izmit Bay (Marmara Sea): case studies before and after the Izmit Earthquake.

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. Yzmit 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.