Performance of butyl rubber-based macroporous sorbents as passive samplers.

In this study, two macroporous butyl rubber (BR)-based sorbents prepared in benzene (H-BR) and in cyclohexane (L-BR) with different porosities were synthesized by cryogelation technique. Their performances as a passive sampler were studied and then compared with commercially available silicon rubber (polydimethylsiloxane, PDMS) passive sampler. For that aim, polycyclic aromatic hydrocarbon (PAH) absorption rates of the sorbents in the short-term and their accumulation capacities in the long-term periods were investigated. Four PAHs (naphthalene, phenanthrene, fluoranthene, and pyrene) with a different number of aromatic rings were utilized. The concentrations of the PAHs in solutions were quantified by fluorescence spectrophotometer. The results showed that the BR sampler prepared in benzene (H-BR) generally has the highest absorption rates for all PAHs. The rate constants k (h-1) of the H-BR, L-BR, and PDMS samplers were found as 1.07, 0.55, and 0.55 for naphthalene; 0.73, 0.16, and 0.09 for phenanthrene; 0.24, 0.26, and 0.08 for fluoranthene; and 0.97, 0.38, and 0.17 for pyrene, respectively. The highest PAH absorption capacity was found for the BR sorbents prepared in benzene for all PAHs. Thus, benzene was selected as the organic solvent rather than cyclohexane for further studies in the preparation of butyl rubber-based samplers. The H-BR possessing the highest absorption rate and capacity underlines their usage as a capable passive sampler for both short- and long-term monitoring activities in the aquatic environments.

Single-, Double-, and Triple-Network Macroporous Rubbers as a Passive Sampler.

Over the past decades, large quantities of organic compounds including polycyclic aromatic hydrocarbons (PAHs) entering aquatic systems create acutely toxic effects and chronic abnormalities in aquatic organisms. Passive sampling is an effective technique to detect organic compounds at very low concentrations in water by accumulating them in their structure to a measurable concentration level. Polymeric passive samplers reported so far have a nonporous structure, and hence, the absorption of organic compounds into the passive sampler is governed by their slow diffusion process. We present here novel macroporous rubber sorbents as monophasic passive samplers with tunable pore morphologies, extraordinary mechanical properties, and high sorption rates and capacities for PAHs. Sorbent materials based on single-network (SN), double-network (DN), and triple-network (TN) butyl rubber were prepared via the cryogelation technique from butyl rubber solutions in benzene as the solvent at -18 °C using a sulfur monochloride cross-linker. To obtain macroporous rubbers with DN and TN structures, the reactions were conducted in the macropores of SN and DN rubber networks, respectively. The porous morphology and the mechanical behavior of the rubbers can be tuned by adjusting the weight ratio wR of the network components. The rubbers exhibit two generations of pores, namely, large and small pores with diameters 40-240 and 14-54 µm, respectively. The sizes of both large and small pores decrease and approach each other as wR is increased. Four PAH compounds, namely, naphthalene, phenanthrene, fluoranthene, and pyrene with two to four aromatic rings, dissolved in filtered seawater with a salinity of 22 ppt were used to highlight the correlations between the properties of macroporous rubbers and their absorption rates and capacities. Nonporous silicone rubber reported before as a passive sampler has the lowest absorption rate and capacity as compared to the macroporous rubbers. The SN rubber absorbs most rapidly PAHs because of its largest porosity, whereas the TN rubber with the smallest pores exhibits the highest sorption capacity.

Pollution and toxicity of sediment in potential dredging sites of the Marmara Sea, Turkey.

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 (LTR, UTR) and UNEP-MAP's guidance document (LCT, UCT), and effects range low and median (ERL, ERM) were used. Total concentrations were found between 562 and 8643 µg kg-1 for PAHs, 4-36 µg kg-1 for PCBs, and 14-190 µg kg-1 for OCPs. The highest ∑PAH concentrations were measured in Golden Horn, and none of the PAH compounds was above ERM. ERL and UCT were exceeded in Istinye and Golden Horn stations. The highest ∑PCBs and ∑OCPs levels were determined in Izmit Bay (IB). ΣPCBs in IB were higher than ERL and LTR, while ΣDDT were found above ERM and UCT. High concentrations of chromium (∼190 mg kg-1) and copper (∼180 mg kg-1) in Golden Horn and mercury in IB (∼4 mg kg-1) were detected. The highest toxicities were observed in Istinye and Izmit Bay. According to the regulations, none of the sediments can be dumped.

Monitoring of organic pollutants in marine environment by semipermeable membrane devices and mussels: accumulation and biochemical responses.

This study involves the monitoring of organic pollutants using transplanted mussels (Mytilus galloprovincialis) as bioindicator organisms and semipermeable membrane devices (SPMDs) as passive samplers. Mussels and SPMDs were deployed to marinas, shipyards and shipbreaking yards on the coastal area of Turkey and retrieved after 60 days. Polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB) and organochlorine pesticide (OCP) compounds were analysed with high-resolution GC-MS. Total PAH concentrations in SPMDs and mussels ranged from 200 to 4740 ng g sampler-1 and from 7.0 to 1130 ng g-1 in wet weight (ww). PCB and OCP concentrations in SPMDs changed between 0.04-200 and 4.0-26 ng g sampler-1, respectively. The highest PCB (190 ng g-1 ww) and OCP (200 ng g-1 ww) concentrations in mussels were measured at shipyard stations. A strong correlation was observed between the PAH and PCB concentrations in SPMDs and mussels. Enzyme assays (acetylcholinesterase, ethoxyresorufin-O-deethylase, glutathione S-transferase, glutathion reductase and carboxylesterase activities) were performed as biomarkers to reveal the effects of pollution on the mussels. There was no clear relationship found between the enzyme levels and the pollutant concentrations in mussels. Integrated biomarker responses were calculated to interpret the overall effect of pollutants.

Heavy metal pollution in sediments and mussels: assessment by using pollution indices and metallothionein levels.

In the present work, the concentration of eight metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn) was determined in the sediments and transplanted and native mussels (Mytilus galloprovincialis). The study was conducted in Turkish marinas, shipyards, and shipbreaking yards. The effect of metal pollution was evaluated by determining the levels of metallothionein (MT) in the mussels. The extent of contamination for each single metal was assessed by using the geoaccumulation index (I geo) and enrichment factor (EF). Whereas, to evaluate the overall metal pollution and effect, the pollution load index (PLI), modified contamination degree (mC d), potential toxicity response index (RI), mean effects range median (ERM) quotient (m-ERM-Q), and mean PEL quotient (m-PEL-Q) were calculated. The influence of different background values on the calculations was discussed. The results indicated a significant metal pollution caused by Cu, Pb, and Zn especially in shipyard and shipbreaking sites. Higher concentrations of MT were observed in the ship/breaking yard samples after the transplantation.

Bioaccumulation-depuration kinetics and effects of phenanthrene on Mediterranean mussel (Mytilus galloprovincialis).

In this study, Mediterranean mussel species, Mytilus galloprovincialis, were exposed to phenanthrene (PHE) due to its ubiquitousness and bioavailability in the aquatic environment. Kinetic parameters of the PHE bioaccumulation and depuration were calculated for an 11-day uptake and subsequent 11-day depuration periods. Those values of kinetic rate constants for uptake and depuration of PHE were calculated as varying between 93-177 and 0.18-0.25, respectively. Negative correlation was observed between the PHE concentrations and kinetic rate constants. Bioaccumulation Factors (BAFs) for the mussels exposed to different PHE concentrations were calculated from both kinetic rate constants and from the experimental data and found between 509-701 and 441-658, respectively. Experimental quantitative structure activity relationship (QSAR) values for PHE were found comparable to the calculated QSARs reported in literature. Two sub-lethal biomarker methods (filtration rate and lysosomal stability) were applied to observe the responses of the mussels throughout the experimental period. Results of both biomarkers show that PHE negatively affects mussels during the uptake of PHE, and mussels were able to recover physiologically at the end of depuration period according to the filtration rate results.

Determination of selected antibiotics in the Istanbul strait sediments by solid-phase extraction and high performance liquid chromatography.

Surface sediments from 12 different locations of the Istanbul Strait and Marmara Sea, Turkey were analysed for five antibiotics belonging to two different groups of widely used pharmaceuticals, tetracyclines (TCs) and fluoroquinolones (FQs), by solid-phase extraction and high performance liquid chromatography. These two groups of antibiotics, mainly used to prevent or treat illness for humans as well as for animals, are frequently detected in the effluent of municipal sewage plants, in the aquatic environments and in soils after being spread by liquid manure. The results of analysis revealed that measured concentrations of individual antibiotics were significantly different depending on sampling location. Chlortetracycline (CTC) was not detected in any of the samples. High concentrations were mainly found in urbanized regions of the Strait. The concentrations of the two tetracyclines ranged from not detectable to 27.3 µg kg(-1) in freeze-dried marine sediments. Comparable results were obtained for the two fluoroquinolones with concentration levels from 1.3 µg kg(-1) up 34.1 µg kg(-1). This study is the first attempt to show the contamination degree of the Istanbul Strait sediments by emerging contaminants. Particular concern should be given concerning their potential side effects caused by the frequent consumption of mussels and fishes captured in the Istanbul Strait.

Distribution of organochlorine pesticides in sediments and mussels from the Istanbul Strait.

This study was conducted to determine the status and trends of organochlorine pesticide (OCP) compounds in the sediment and mussel samples collected along the Istanbul Strait and from the coasts of an island in the Marmara Sea. The total concentrations of OCPs were found in the range of 40-13,852 pg g(-1) dry weight for sediments and 5,195-12,322 pg g(-1) wet weight for mussels. The levels of OCPs in both sediments and mussels were dominated by DDTs and HCHs; ß-HCH, 4,4(')-DDD and 4,4(')-DDE were the major pollutants. The degree of sediment pesticide contamination was more severe in the inner part of the strait. OCP concentrations in sediments and mussels were compared with the sediment guideline values and legal limits for human health, respectively. The results showed that OC pesticide contamination in the strait might not pose a serious threat to the health of the marine inhabitants at most of the stations.

Evaluation of butyl rubber as sorbent material for the removal of oil and polycyclic aromatic hydrocarbons from seawater.

Ecological disasters resulting from oil spills have created a great need to find more efficient materials for oil spill cleanup. This research highlights the use of a novel macroporous polymeric material based on butyl rubber (BR) as a sorbent in an oil spill cleanup. The sorption capacity of BR for crude oil and petroleum products is 15-23 g g(-1) as compared to the value of 10-16 g g(-1) obtained using a nonwoven polypropylene (PP), a widely used commercial oil sorbent. BR sorbent is reusable after simple squeezing and its continuous sorption capacity for crude oil is 7.6 g g(-1) in each cycle, about 3 times the capacity of the PP sorbent BR sorbents also remove efficiently polycyclic aromatic hydrocarbons (PAHs) such as acenaphthene and pyrene from seawaters. The results suggest that the rubber sorbents are a better alternative to the widely used PP sorbents by improving the efficiency of oil sorption and the reusability of the sorbent.

Metals in the surface sediments of Istanbul Strait (Turkey).

Surface sediments from 17 stations in the Istanbul Strait and Marmara Sea were collected and analysed for major and trace elements by wavelength-dispersive X-ray fluorescence spectrometry (WDXRF). Metal concentrations in surface sediments varied from 1.3 to 7.2 % for Al, 4.8 to 18 mg kg(- 1) for As, 119 to 599 mg kg(- 1) for Ba, below detection limit (bdl) to 6.6 mg kg(- 1) for Cd, 18 to 222 mg kg(- 1) for Cr, 7.6 to 180 mg kg(- 1) for Cu, 1.0 to 5.5 % for Fe (10 000 to 55 000 mg kg(- 1)), 171 to 718 mg kg(- 1)for Mn, 3.3 to 64 mg kg(- 1) for Ni, 4.5 to 461 mg kg(- 1) for Pb, 1.3 to 68 mg kg(- 1) for Sn, 19 to 170 mg kg(- 1) for V and 16 to 859 mg kg(- 1) for Zn. Three tools have been applied in order to evaluate metal pollution in the sediments; Sediment quality guidelines (SQGs), enrichment factors (EFs) and geoaccumulation index (I(geo)). SQGs values indicate that Pb and Ni are the most likely contaminants to cause adverse biological effects. On the other hand, both metal enrichment factors and geoaccumulation index show that As, Zn, Pb and Cd contaminations exist in the entire study area and contamination of other metals is also present in some sites depending on the sources. Factor analysis (FA) receptor modelling technique was applied to investigate the sources affecting surface sediment samples at the Istanbul Strait.

Bioconcentration and phototoxicity of selected PAHs to marine mussel Mytilus galloprovincialis.

This study assessed the sensitivity of Mytilus galloprovincialis (Mediterranean mussel) to UV-induced toxicity of pyrene, phenanthrene, fluoranthene and chrysene. Mussels were exposed to two different polyaromatic hydrocarbon (PAH) concentrations within the solubility limits for 7 days, after which the filtration rate and the blood cell stability of the mussels were determined to quantify the effects of PAHs. Mussel tissues were analysed at the end of the experiments to determine the degree of bioaccumulation of PAHs and in order to make quantitative body-burden/effect links. The differences between the tissue residue based effective concentration (TEC(20)/TEC(50)) values before and after ultraviolet (UV) exposure provided a measure of phototoxicity of the bioaccumulated PAHs. Out off the biomarkers applied, Neutral Red Retention (NRR) results showed that the most toxic compound is chrysene in the absence of UV. The NRR technique was found more sensitive compared to Fitration Rate (FR) technique. The toxicities of chrysene, phenanthrene and pyrene were enhanced by UV, while fluoranthene was toxic in the absence of UV lighting and its toxicity did not change by UV application.

Photoinduced toxicity of selected PAHs to the marine microalga Phaeodactylum tricornutum.

In this study, the effects of different concentrations of pyrene, phenanthrene, fluoranthene, and chrysene within the solubility limits of the chemicals on marine microalgal species of Phaeodactylum tricornutum were examined under UV-A and UV-B lights by application of batch toxicity tests. The algal species were also exposed to the individual PAHs under cool-white fluorescent bulbs in the same laboratory conditions in order to compare the results with the responses of UV-exposed organisms. EC50 values calculated with the trimmed Spearman Karber method demonstrate that the UV light dramatically enhances the toxicity of the selected model PAHs. In most cases, the magnitude of increase in PAH toxicity was directly related to the concentration of individual PAHs and the duration of UV-lighting.

Effects of pyrene on mussels in different experimental conditions.

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.

Comparison of several toxicity tests applied to complex wastewaters and mussel biomarkers in receiving waters.

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.