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PubMed2006

Effects of lead-contaminated sediment on Rana sphenocephala tadpoles.

We exposed larval southern leopard frogs (Rana sphenocephala) to lead-contaminated sediments to determine the lethal and sublethal effects of this metal. Tadpoles were laboratory-raised from early free-swimming stage through metamorphosis at lead concentrations of 45, 75, 180, 540, 2360, 3940, 5520, and 7580 mg/kg dry weight in sediment. Corresponding pore water lead concentrations were 123, 227, 589, 1833, 8121, 13,579, 19,038, and 24,427 microg/L. Tadpoles exposed to lead concentrations in sediment of 3940 mg/kg or higher died within 2 to 5 days of exposure. At lower concentrations, mortality through metamorphosis ranged from 3.5% at 45 mg/kg lead to 37% at 2360 mg/kg lead in sediment. The LC50 value for lead in sediment was 3728 mg/kg (95% CI = 1315 to 72,847 mg/kg), which corresponded to 12,539 microg/L lead in pore water (95% CI = 4000 to 35,200 microg/L). Early growth and development were depressed at 2,360 mg/kg lead in sediment (8100 microg/L in pore water) but differences were not evident by the time of metamorphosis. The most obvious effect of lead was its pronounced influence on skeletal development. Whereas tadpoles at 45 mg/kg lead in sediment did not display permanent abnormalities, skeletal malformations increased in frequency and severity at all higher lead concentrations. By 2360 mg/kg, 100% of surviving metamorphs displayed severe spinal problems, reduced femur and humerus lengths, deformed digits, and other bone malformations. Lead concentrations in tissues correlated positively with sediment and pore water concentrations.

Animals↗

PubMed1998

Sediment toxicity evaluation for hexachlorobenzene: spiked sediment tests with Leptocheirus plumulosus, Hyalella azteca, and Chironomus tentans.

Hexachlorobenzene (HCB) is a hydrophobic organic chemical that has shown a lack of toxicity in aquatic tests at concentrations up to and exceeding the solubility limit. The equilibrium partitioning approach to deriving sediment quality benchmarks, which assumes that toxicity can be predicted based on contaminant concentrations in interstitial water, predicts that HCB will not produce direct toxicity to benthic invertebrates as a sediment contaminant. However, the potential for toxicity due to direct exposure to sediment-adsorbed HCB has not been thoroughly established. This study evaluated the survival and growth of the estuarine amphipod Leptocheirus plumulosus, the freshwater amphipod Hyalella azteca, and the midge Chironomus tentans (freshwater) following 10-day exposure to sediment spiked with a range of HCB concentrations. H. azteca was tested under both freshwater and estuarine (10 ppt salinity) conditions. No significant toxicity was observed for any test species at the highest test concentration (60 mg/kg normalized to 1% organic carbon). Minimum detectable differences were less than or equal to 20% for three of eight test endpoints. The observed results add to the available weight of evidence indicating a limited potential for HCB-related sediment toxicity to benthic invertebrates.

Animals↗

PubMed2002

Small-scale distribution of interstitial nitrite in freshwater sediment microcosms: the role of nitrate and oxygen availability, and sediment permeability.

The spatial distribution of interstitial NO2(-) concentrations was studied in NO3(-)-exposed freshwater sediment microcosms, using pore water extractions as well as ion-selective microsensors. Porewater extractions revealed ecotoxicologically critical NO2(-) concentrations in hypoxic and anoxic sediment layers in which significant NO3(-) consumption took place. In contrast, the use of ion-selective microsensors demonstrated the high capacity of the thin oxic surface layer of the sediments to consume NO2(-) and to produce NO3(-). Two modes of NO3(-) supply to the sediments were compared: In treatments with NO3(-) supply to the overlying water, a subsurface maximum of NO2(-) concentration was observed, coinciding with the site of maximum NO3(-) consumption. When NO3(-) was perfused up through the sediment cores, however, NO2(-) accumulated throughout the entire sediment column. Such spatially extensive NO2(-) accumulations were only observed in sediments poor in organic matter with a relatively high permeability. By manipulating the O2 content of the overlying water, the release of NO2(-) from the sediments could be influenced: In treatments with air-saturated overlying water, the sediments did not release detectable amounts of NO2(-) into the water phase. When kept hypoxic (25% air saturation) instead, significant NO2(-) accumulations were recorded in the overlying water. These findings suggest that in treatments with air-saturated overlying water, NO2(-) that was produced in deeper sediment layers (denitrifying conditions) was completely consumed at the oxic sediment surface (nitrifying conditions) before it could reach the overlying water.

Biological Availability↗

PubMed2005

Seasonal variations of trace metal chemical forms in bed sediments of a karstic river in Lebanon: implications for self-purification.

Although Lebanon has abundant water, its rivers are polluted and aquifer water mismanaged. Effective river water usage requires an understanding of the geochemistry of polluting metals in catchments. Climate is "Mediterranean": wet winters and dry summers. Active sediment flushing is restricted to winter high discharge episodes. Except in winter, water column pollutants are removed by precipitation or sorption to the surface of static bed sediments. Hence (1) does winter flushing of contaminated sediment and replacement by clean sediment favour self purification? (2) does the distribution of metals between extractable fractions change seasonally and thereby affect metal bioavailability ? Results on the distribution of metals are reported for Fe, Pb, Zn, Cu and Cd in bed sediments from Nahr Ibrahim (a karstic river) for summer and winter. A Tessier-like sequential extraction scheme was applied to samples (< 75 microm) for five locations along a 13 km stretch to the sea. Water pH was above 8.2 at all locations implying a very low solubility for Fe. Sediment was derived from catchment soils and limestone. Total sediment Fe increased in winter at all sites following deposition of eroded soil from upstream. Cadmium, Cu and Pb derived from polluting sources; the sources of Zn were more complex. Dilution by clean sediment explained winter reductions in total Cd, Cu and Pb; Zn changes were less consistent. Iron occurred mostly (> 77 sum of fractions) in the residual fraction compared with 6- 31 for pollutants; residual Cu and Zn showed a small increase in winter whereas Cd and Pb did not change. All readily exchangeable metals decreased in winter and the carbonate bound forms predominated in both seasons. Nahr Ibrahim has a high capacity for self purification and metal resolubilization from sediment will be limited by the solubility of carbonate forms.

Chemical Fractionation↗

PubMed2006

Evaluation of an exposure assay to measure uptake of sediment PAH by fish.

The ecological risks of polynuclear aromatic hydrocarbons (PAH) in aquatic sediments will vary with both toxicity and bioavailability to aquatic biota. While there are standardized protocols to test the acute toxicity of sediment-borne compounds to aquatic invertebrates, there are none for assessing bioavailability to fish. We found that sediment-borne PAH caused an exposure-dependent induction of cytochrome P450 (CYP1A) enzymes in rainbow trout (Oncorhynchus mykiss) fingerlings exposed in semi-static 96 h bioassays, as shown by increased activity of ethoxyresorufin-o-deethylase (EROD). Assuming that PAH are taken up by trout due to partitioning from organic and inorganic constituents of sediments, we tested the effect of different test variables on bioaccumulation using induction as an index of exposure. EROD activity increased with exposure of fish to increasing volumes of sediments containing PAH, i.e., with increasing ratios of sediment to water. Uptake of single compounds from sandy sediments did not differ from uptake from clay or low organic (7% LOI - loss on ignition) sediments, but decreased when organic content was very high (58% LOI). Maximum induction was observed within 24 h of exposure and at 7.5 degrees C relative to 15, 22, or 28 degrees C. Storage and handling techniques had minor effects on sediment EROD induction potency. Absolute EROD activity was greater in white sucker (Catostomus commersoni) a benthic species, than in trout, a pelagic species. However, when basal (negative control) activity was accounted for, there was no difference in response between the species. Together, these experiments provide a basis for developing a standard protocol to test the bioavailability to fish of sediment-borne PAH.

Animals↗

PubMed1996

Composition and distribution of polycyclic aromatic hydrocarbon contamination in surficial marine sediments from Kitimat Harbor, Canada.

Surficial marine sediments from 20 sites within the Kitimat fjord system were analyzed for polycylic aromatic hydrocarbons (PAHs). Levels of the sum of the 16 USEPA priority pollutant PAHs varied from below detection limits (ca. 1 microg x g-1) to over 10 000 microg x g-1. Sediment PAH levels were highest in the immediate vicinity of a large aluminum smelter at the head of Kitimat Arm, and declined rapidly with increasing distance from the smelter. However, even at some of the more distant sites which are geographically isolated from the smelter PAH levels were elevated. The PAH distribution in the fjord system is consistent with a combination of aeolian and fluvial transport of PAHs emitted by the aluminum smelter at the head of Kitimat Arm. The mixture of PAHs present was qualitatively similar in all samples analyzed, including those from the distant sites. All aspects of the PAH composition are consistent with combustion generated PAHs. A correlation between PAH levels and sediment organic carbon was observed; however, this was only significant for highly contaminated sites in the harbor. This probably reflects the high organic content of particulate emissions from the smelter, rather than equilibrium partitioning of PAHs to sediment organic carbon within the harbor itself.

Aluminum↗

PubMed2004

Pesticides and PCBs in sediments and fish from the Salton Sea, California, USA.

The Salton Sea, the largest manmade lake in California, is officially designated by the State of California as an agricultural drainage reservoir. The purpose of this study was to determine organochlorine and organophosphorous pesticides, as well as polychlorinated biphenyl (PCB) concentrations in sediments and fish tissues in the Salton Sea and evaluate the relative ecological risk of these compounds. Sediment samples were taken during 2000-2001 and fish tissues (Tilapia mossambique, Cynoscion xanthulu) were collected in May 2001. All samples were analyzed for 12 chlorinated pesticides, 6 organophosphorus pesticides, and 55 polychlorinated biphenyl (PCB) congeners. SigmaDichlorodiphenyltrichloroethane (SigmaDDT) and total PCB concentrations observed in sediments ranged from 10 to 40 and 116 to 304 ng/g dry wt, respectively. DDT/DDD ratios in sediments and fish tissues of the northern Sea in 2001 indicated recent DDT exposure. Lindane, dieldrin, dichlorodiphenylethane (DDE) and total PCB concentrations detected in sediments exceeded probable effect levels established for freshwater ecosystems, and pp-DDE and total PCB concentrations were higher than effect range-median values developed for marine and estuarine sediments. In fish liver, concentrations of endrin and SigmaDDT exceeded threshold effect level established for invertebrates. SigmaDDT concentrations detected in fish tissues were higher than threshold concentrations for the protection of wildlife consumers of aquatic biota. DDE concentrations in fish muscles tissues were above the 50 ng/g concentration threshold for the protection of predatory birds. Dimethoate, diazinon, malathion, chlorpyrifos, disulfoton varied from < or = 0.15 to 9.5 ng/g dry wt in sediments and from < or = 0.1 to 80.3 ng/g wet wt in fish tissues. Disulfoton was found in relatively high concentrations (up to 80.3 ng/g) in all organs from Tilapia and Corvina. These results demonstrate continued contamination of specific organochlorine compounds in sediments and resident fish species of the Salton Sea.

Analysis of Variance↗

PubMed2004

Variability of parameters measured during the resuspension of sediments with a particle entrainment simulator.

The release of contaminants from sediments is an important problem facing environmental managers concerned with issues such as maintenance dredging, habitat restoration and dredge spoil placement. While there are laboratory methods to assess the remobilization of contaminants from resuspended sediments, little is known about how their operating characteristics influence a sediments response to resuspension. In this study, a particle entrainment simulator (PES) for resuspending sediments was evaluated by assessing variability among replicates and over operation time (12 h) for three estuarine sediments. These sediments varied in physical and chemical properties as well as the degree of metal contamination. Results showed that under identical resuspension conditions, there was low variability among sediment replicates. Sediment properties and the degree of metal contamination affected the magnitude and variation in water column parameters and contaminant release. Fine-grained sediments affected water column parameters, which stabilized over several hours of resuspension. While metal concentrations in the aqueous and particulate samples varied throughout operation, variation was highest for Cd and Ni. Compared to other methods used to evaluate the effects of sediment resuspension, the PES has operational advantages such as the ability to monitor water column conditions and resuspend sediment at specified energy levels. Overall, the PES provided reproducible conditions of resuspension effects among sediments varying in composition and contamination, demonstrating its value as a tool to evaluate contaminant mobility.

Geologic Sediments↗

PubMed2006

Dissolution of resin acids, retene and wood sterols from contaminated lake sediments.

The dissolution potency of hydrophobic resin acids (RAs), retene and wood sterols from sediments was studied. These wood extractives and their metabolites are sorbed from pulp and paper mill effluents to downstream sediments. With harmful components like these, sediments can pose a hazard to the aquatic environment. Therefore, sediment elutriates with water were produced under variable conditions (agitation rate and efficiency, time), and concentrations of the dissoluted compounds were analyzed. Both naturally contaminated field sediments and artificially spiked sediments were studied. By vigorous agitation RAs can be released fast from the sediment matrix and equilibrium reached within 3 days. Compared to RAs, desorption of retene from lake sediment was slower and did not completely reach equilibrium in 23 days. Sterols spiked to pristine sediment with a 33-day contact time desorbed faster than those associated authentically with industrial sediment of from a contaminated lake. Simulating the water turbulence adjacent to a sediment surface by low and high rate of agitation in the laboratory, an increase in the mixing rate after 43-day elutriation suddenly released a high amount of wood sterols. The results indicate wide variation between hazardous chemicals in their tendency to dissolution from sediment solids. Erosion and hydrology adjacent to the sediment surface, as well as risks from dredging activities of sediments, may expose lake biota to bioactive chemicals.

Acids↗

PubMed2006

Predicting organic contaminant concentrations in sediment porewater using solid-phase microextraction.

Because of its cost and time saving features, solid-phase microextraction (SPME) is a leading candidate as a biomimic technique in assessing the bioavailable fraction of hydrophobic organic contaminants (HOCs) in sediment porewater. However, no predictive modeling framework in which to systematically address the effect of key parameters on SPME performance for this application exists. In this study, we derived two governing equations to predict (1) the minimum sediment volume (V(s)min) required to achieve non-depletive conditions, and (2) dissolved phase HOC porewater concentrations (C(pw)) as functions of HOC- and sediment specific characteristics in a conceptual three compartment system. The resulting model predicted that V(s)min was independent of HOC concentrations both in sediment and porewater, but did vary with hydrophobicity (characterized by logK(ow)), the fraction of sediment porewater (f(pw)), and the volume (V(f)) of the SPME sorbent phase. Moreover, the effects of these parameters were minimized (i.e., V(s)min reached plateaus) as logK(ow) approached 4-5. Model predictions of C(pw), a surrogate for SPME-based detection limits in porewater, decreased with increasing sediment volume (V(s)) at low V(s) values, but rapidly leveled off as V(s) increased. A third result suggested that the sediment HOC concentration required for SPME is completely independent of K(ow). These results suggest that relatively small sediment volumes participate in exchange equilibria among sediment, porewater and the SPME fiber, and that large sediment HOC reservoirs are not needed to improve the detection sensitivity of SPME-based porewater samplers. The ultimate utility of this modeling framework will be to assist future experimental designs and help predict in situ bioavailability of sediment-associated HOCs.

Algorithms↗

PubMed2005

Twin comprehensive two-dimensional gas chromatographic system: concept and applications.

A twin GC x GC system has been designed which enables the analysis of a sample by means of two different and independent column combinations simultaneously. Both combinations are incorporated in the same oven, using the same temperature programme, and are fed using a 50:50 column-entrance-split. It is demonstrated that, employing combinations of a conventional non-polar x polar and a reversed-type polar x non-polar column set, the information content is as high, and the analytical performance is as good as when using two separate GC x GC systems. That is, there is an appreciable gain of time and a reduction of costs without any loss of quality. The general usefulness of performing, and comparing two mutually different GC x GC runs is further illustrated with FAMEs in olive oil, and pollutants in a sediment sample.

Chromatography, Gas↗

PubMed2005

Detection of nitroaromatic and cyclic nitramine compounds by cyclodextrin assisted capillary electrophoresis quadrupole ion trap mass spectrometry.

An Agilent 3DCE capillary electrophoresis system using sulfobutylether-beta-cyclodextrin (SB-beta-CD)-ammonium acetate separation buffer pH 6.9 was coupled to a Bruker Esquire 3000+ quadrupole ion trap mass detector via a commercially available electrospray ionization interface with acetonitrile sheath flow. The CE-MS system was applied in negative ionization mode for the resolution and detection of nitroaromatic and polar cyclic or caged nitramine energetic materials including TNT [2,4,6-trinitrotoluene, formula mass (FW) 227.13], TNB (1,3,5-trinitrobenzene, FW 213.12), RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine, FW 222.26) HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine, FW 296.16), and CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, FW 438.19). The CE-MS system conformed to the high-performance liquid chromatography with ultraviolet absorbance detection (HPLC-UV) and HPLC-MS reference methods for the identification of energetic contaminants and their degradation products in soil and marine sediment samples.

Aza Compounds↗

PubMed2006

New cold-fiber headspace solid-phase microextraction device for quantitative extraction of polycyclic aromatic hydrocarbons in sediment.

A new automated headspace solid-phase microextraction (HS-SPME) sampling device was developed, with the capability of heating the sample matrix and simultaneously cooling the fiber coating. The device was evaluated for the quantitative extraction of polycyclic aromatic hydrocarbons (PAHs) from solid matrices. The proposed device improves the efficiency of the release of analytes from the matrix, facilitates the mass transfer into the headspace and significantly increases the partition coefficients of the analytes, by creating a temperature gap between the cold-fiber (CF) coating and the hot headspace. The reliability and applicability of previously reported cold-fiber devices are significantly enhanced by this improvement. In addition, it can be easily adopted for full automation of extraction, enrichment and introduction of different samples using commercially available autosampling devices. Sand samples spiked with PAHs were used as solid matrices and the effect of different experimental parameters were studied, including the extraction temperature, extraction time, moisture content, and the effect of sonication and modifier under optimal experimental conditions, linear calibration curves were obtained in the range of 0.0009-1000 ng/g, with regression coefficients higher than 0.99 and detection limits that ranged from 0.3 to 3 pg/g. Reproducible, precise and high throughput extraction, monitoring and quantification of PAHs were achieved with the automated cold-fiber headspace solid-phase microextraction (CF-HS-SPME) device coupled to GC-flame ionization detection. Determination of PAHs in certified reference sediments using the proposed approach exhibited acceptable agreement with the standard values.

Calibration↗

PubMed2004

Environmental impact of heavy metals from dredged and resuspended sediments on phytoplankton and bacteria assessed in in situ mesocosms.

Past and on-going reclamation, dredging, construction and shipping activities impact Ponggol Estuary, located on the northeastern coast of Singapore. Tin, lead, nickel, cadmium, and copper in particulate and dissolved fractions and sediments ranged from ND (undetectable)-92 ppm, ND-303.2 ppm, ND-2818.4 ppm, ND-74.4 ppm and ND-1117.7 ppm, respectively. Intensive dredging activity during the monitoring period may have led to the resuspension and bioavailability of particulate metals. This was tested by the exposure of phytoplankton and bacteria in mesocosms to previously measured environmental levels of heavy metals and the contaminated sediments with the highest heavy metal concentrations from one of the impacted sites. The results showed significant copper toxicity to phytoplankton and autotrophic bacteria, followed by nickel and lead at all concentrations tested. Enhanced rates of heterotrophic bacterial production and total bacterial abundance were observed in treatments with higher metal concentrations. Among the various treatments, particulate and sediment metal concentrations were significantly different from those of the control. Mesocosms using contaminated sediments with the highest metal concentrations compared with the control showed a bioavailability of metals that resulted in the inhibition of phytoplankton and autotrophic bacteria. High concentrations of copper (5.52-11.35 mg L(-1)) and nickel (2.42-2.71 mg L(-1)) observed in the aqueous phase of treatment mesocosms, and attributed to release from the contaminated sediments could account for the toxicity to phytoplankton and autotrophic bacteria.

Bacteria↗

PubMed2005

Body residues: a key variable to analyze toxicity tests with Chironomus riparius exposed to copper-spiked sediments.

Fourth instar Chironomus riparius larvae were exposed to four sediments spiked with copper. Length and copper concentration in the tissue were monitored daily. Kinetics data analysis was performed by fitting a one-compartment model. The analysis of growth data was performed using an energy-based approach which estimates a no-effect concentration (NEC). The elimination rate of copper did not depend on the sediment characteristics, whereas the bioconcentration factor differed by a factor of 10 among the tested sediments, accounting for differences in copper bioavailability. Consequently, the NEC expressed in term of exposure concentrations differed substantially between sediments. In contrast, the NEC expressed in terms of body residues did not depend on the sediment characteristics. This work links, for the first time, a mechanistic effects model with the critical body residue approach, and could contribute to develop relevant tools for sediment risk assessment.

Animals↗

PubMed2004

A review of factors affecting the release and bioavailability of contaminants during sediment disturbance events.

The factors affecting the release and bioavailability of contaminants present in sediments during natural and anthropogenic disturbance events are discussed and our current state of understanding of these processes reviewed. Published data are focused on the distribution of contaminants within undisturbed sediment, their affinities to the various solid-phase fractions of sediment and the interaction of contaminants between sediment and pore water. Sediment disturbance can lead to changes in the chemical properties of sediment that stimulate the mobilisation of contaminants. Research shows that changes in both redox potential (Eh) and pH can accelerate desorption, partitioning, bacterial degradation and the oxidation of organic contaminants. However, these processes are both sediment- and compound-specific. By affecting the affinity of contaminants to sediments, disturbance events in turn can have a significant effect on their bioavailability. Few studies have examined this phenomenon, and it is clear from the data available that there are gaps in our understanding in a number of key areas when assessing the release of contaminants from sediments: the fate of contaminants in undisturbed sediments and those that are not subjected to major disturbances, the kinetic processes that regulate metal release during changes in redox potential, the release of organometallic compounds from sediments during resuspension, the bioavailability of organic and organometallic compounds and the processes affecting contaminant release.

Animals↗

PubMed2005

The speciation and bioavailability of mercury in sediments of Haihe River, China.

Twenty-one sediment samples in 11 sites along the Haihe River and Dagu Drainage River, Tianjin, China, were analyzed to investigate the pollution status and bioavailability of mercury (Hg). The results showed that the Haihe River was slightly polluted with Hg when flowing through Tianjin city. On the contrary, the sediments collected from Dagu Drainage River, an important drainage river in Tianjin, were found to have very high Hg concentrations and the highest concentration reached 8779.1 ng g(-1) (dry weight). The methylmercury (MeHg) concentrations accounted for 0.1-2.4% (average: 0.9%) of total mercury (HgT) and were strongly influenced by HgT (r=0.91, p=0.99, n=20) and total organic carbon (TOC; r=0.76, p=0.99, n=20) contents in sediments. Moreover, a five-step sequential selective extraction (SSE) procedure was used to study the bioavailability of Hg in sediments. The mercury in sediments existed mainly as element Hg and mercury sulfide, which accounted for 46.5% and 39.0% of HgT, respectively. The percentage of exchangeable Hg (defined as water soluble Hg plus 'human stomach acid' soluble Hg) was only 0.1-4.6%. The distribution of exchangeable Hg showed an obvious difference to that of HgT, indicating that the HgT concentrations were absolutely insufficient to evaluate the risk of Hg in sediments.

Biological Availability↗

PubMed2006

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.

Disasters↗