Nuray Balkis

Polybenzoxazine: A Powerful Tool for Removal of Mercury Salts from Water

A reusable macroporous polybenzoxazine resin with high specific surface area was prepared as sorbent material for the removal of mercury salts. For this purpose, allyl-functionalized bis-benzoxazine was cured in dimethyl sulfoxide by thermally activated ring-opening polymerization at 180 °C for 3 d followed by a freeze-drying process. The porous structure of the resin was confirmed by SEM analysis and N2 adsorption/desorption studies at 77.3 K. Among various metal ions, namely, Pb(II), Fe(II), Mn(II), Cu(II), Zn(II), and Cd(II), the porous polybenzoxazine resin exhibited a specific sorption behaviour towards Hg(II). Mainly chemisorption and to some extent adsorption mechanisms were proposed for the observed high loading capacity of the resin. As evidenced by FTIR spectral analysis, the chemisorption is attributed to the coordination system formed between free OH and tertiary amino groups in the polybenzoxazine structure and Hg(II) ions. It was also demonstrated that the porous polybenzoxazine can be regenerated simply by treatment with acids. The resin was recycled for up to seven cycles without any significant loss of activity, as proved by sorption and desorption experiments.

Heavy metal concentrations in water, suspended matter, and sediment from Gökova Bay, Turkey

The contents of heavy metals (Fe, Mn, Pb, Cu, Cd, and Hg) dissolved in water and suspended solids of Gökova Bay—partly and fully sampled in 2005 and 2006, respectively—are quite higher than the average values encountered in uncontaminated sea water. The high concentrations are associated with terrestrial inputs from the mining zones and anthropogenic (domestic + industrial) sources. Moreover, the distribution of Fe and Cu is affected by primary production because these elements function as nutrients in biological activities. The Cr, Ni, and Fe concentrations of surface sediments are above the shale average. The Cr and Ni contents of surface sediments representative of river mouths strongly correlate with total phosphorus contents. In a sulfide-poor environment, Pb and Cu were concentrated at a higher ratio in surface sediments than Cd, probably due to higher stabilities of their surface complexes with amorphous iron oxides and clay minerals existing as major components in the sediments. The exceptional enrichment of Zn may be attributed to double oxide formation with amorphous iron oxides in sediments. The high metal values are most probably caused by terrestrial inputs from anthropogenic sources and the mining zones at the southeast part of the bay. The Al, Mn, Pb, Cu, Zn, and Hg contents are below the shale average. The low values have possibly originated from the coarse-grained sandy sediments having a low affinity for metals. There are no distinct differences in the metal distributions in water and suspended matter between the years 2005 and 2006 in the bay, probably due to low sedimentation rates.

The effect of Marmara (İzmit) Earthquake on the chemical oceanography of İzmit Bay, Turkey

After the Marmara (Izmit) Earthquake (magnitude 7.4) on 17 August 1999, chemical oceanographical characteristics of Izmit Bay were investigated in order to examine the possible effects of the refinery fire and uncontrolled entrance of domestic wastes to the surface waters. The dissolved oxygen (DO) content of the water column in August 1999 was the lowest value of all the measurement periods. It was found to be lower than the detection limit of the method (0.03 mgl(-1)) in the lower layer of eastern and central basins of the Bay, whereas the dissolved hydrogen sulfide (DHS) values were high, varying between 0.14 and 1.28 mgl(-1). The deficiency of DO and in turn formation of DHS were caused by the spreading petroleum from the refinery fire onto the sea surface and waste loads from the damaged municipal waste effluent system. The increasing organic/inorganic loads into the Bay stimulated the phytoplankton blooms which cause locally saturated DO concentrations in the eastern basin during autumn 1999. DO concentrations increased in lower layer waters during winter, whilst DHS formation disappeared when water originating from the Marmara Sea replenish the water column of Izmit Bay. However, DHS formation established again in August 2000.

Metal (Al, Fe, Mn and Cu) distributions and origins of polycyclic aromatic hydrocarbons (PAHs) in the surface sediments of the Marmara Sea and the coast of Istanbul, Turkey

In this study, total metal (Al, Fe, Mn and Cu) and PAHs analyses have been done in the surface sediments. Sediment samples have been collected from seven parts of the Marmara Sea and the coast of Istanbul during 2009. Total Al, Fe, Mn and Cu contents vary between 1.8% and 5.4%; 1.1% and 2.8%; 122 and 259 μg g(-1); 27 and 416 μg g(-1), respectively. EF and CF values of Fe and Mn are lower than 1.5 and 1, respectively, in all the stations. Total PAH contents range between 135 and 6009 ng g(-1) in the surface sediments. The origin of PAHs has been found pyrolitic according to the Phe/Ant ratio in the all stations. Contrastingly, at K0, MKC and MY1 Stations, PAH origins have been observed petrogenic according to the Flu/Pyr ratio.

T-PAH contamination in Mediterranean mussels (Mytilus galloprovincialis, Lamarck, 1819) at various stations of the Turkish Straits System

Mussels (Mytilus galloprovincialis) from the Turkish Straits Systems were analyzed for sixteen parent polycyclic aromatic hydrocarbon (PAH) contents by high performance liquid chromatography (HPLC). This marine organism was selected because of its multitude, wide distribution, being bio indicator for the pollution and consumption by humans. Total PAH concentrations ranged from 1.2 to 589 μg g(-1) in Istanbul Strait, 0.94-36.4 μg g(-1) in Marmara Sea and 0.4-47.9 μg g(-1) in Çanakkale Strait during the samplings. According to the results Istanbul and Çanakkale Straits are more polluted than the Marmara Sea.

Presence of the diatom genus Pseudo-nitzschia and particulate domoic acid in the Golden Horn Estuary (Sea of Marmara, Turkey)

The potentially toxic diatom genus Pseudo-nitzschia and particulate domoic acid (pDA) concentrations were investigated weekly to bi-weekly from October 2013 to September 2014 in the Golden Horn Estuary. Pseudo-nitzschia species were detected in 324 of the 666 samples (∼49%). Two species, Pseudo-nitzschia calliantha and Pseudo-nitzschia pungens, were identified based on the scanning electron microscopy examination. A bloom of P. calliantha occurred between May and June, average cell density, 1.1 × 106 cells L−1 in May. Pseudo-nitzschia calliantha was commoner than P. pungens almost throughout the study period. They occurred over a wide temperature range (7.4–26.3°C) and moderate salinity (5.9–19.9). The highest cell density occurred at 14.7–19.6°C and 18.5–19.0 salinity, in the lower and middle estuary in winter and late spring. Pseudo-nitzschia species were found in very low densities in the upper estuary, which has variable salinity and low light availability due to high concentrations of suspended material. The pDA concentration in seawater was 0.03–1.0 µg L−1. The distribution pattern of pDA coincided with the presence of Pseudo-nitzschia. Pseudo-nitzschia abundance was low in October, when pDA was highest. There was a highly positive correlation between Pseudo-nitzschia abundance and salinity/Secchi depth/pH (p ≤ .001), but a negative correlation with inorganic nutrients and Si:N (p < .001). pDA was positively correlated with temperature/salinity and Secchi depth, but negatively correlated with inorganic nutrients (p < .001). Low light availability and highly variable salinity may limit the growth of Pseudo-nitzschia in the upper estuary and the presence of pDA throughout the study area may be related to transport by particulate matter.

Preparation of microporous organic polymer through Schiff base chemistry and its potential application

The uniform microporous organic polymer (MOP) was obtained in one-pot and one-step polymerization process through Schiff base chemistry under thermal conditions. The obtained anthraquinone–melamine based MOP (AM-MOP) displays high surface area (215 m2/g). AM-MOP was manually filled into a column with high pressure and used as packing material in the high-performance liquid chromatographic applications. The analysis of compounds such as polycyclic aromatic hydrocarbons, pesticides, flavonoids, and phenolic acids was performed to display a possible application by using AM-MOP packed column. Compared to the commercial columns, AM-MOP exhibits better selectivity factor and column efficiency arising from its strong π–π interaction activity. Furthermore, it has similar solvent uptake in both polar and nonpolar media, which explains good compatibility of the material with all mobile phases, from acetonitrile to methanol and water.

Toxic metal (Pb, Cd and Hg) levels in the nearshore surface sediments from the European and Anotolian Shores of Bosphorus, Turkey.

In this study, some toxic metal such as Pb, Cd and Hg analyzes have been done in the nearshore surface sediments. Sediment samples have been collected from five parts from the European and Anotolian Shores of the Bosphorus during 2003-2004. Total Pb, Cd and Hg contents vary between <0.01 μg g(-1) and 238 μg g(-1); <0.01 μg g(-1) and 0.92 μg g(-1); 0.001 μg g(-1) and 0.45 μg g(-1), respectively. Contamination Factor (CF) values of Pb and Cd range between 1 and 3 whilst CF values of Hg are lower than 1 in all the stations. It means that there are no Hg metal enrichment by natural or anthropogenic inputs contrary to moderately contamination for Pb and Cd metals throughout the Bosphorus sediments.

Seasonal variations of epipelic algal community in relation to environmental factors in the Istanbul Strait (the Bosphorus), Turkey.

This study was implemented to investigate the species composition, abundance, seasonal variations and diversity of epipelic algae, to determine environmental variables affecting them and to reveal the accumulation of total organic carbon in the sediment in the coastal zone of the Istanbul Strait, Turkey. Epipelic algal community consisted of 44 taxa with a low diversity. The sediment structure which is highly unstable due to the high hydrodynamism of the zone played a dominant role as the main factor in the epipelic algal flora along the coasts of Istanbul Strait. Low TOC and high carbonate values also support this result. The dominance of cyanobacteria in some periods and, as a result of this, the record of the lowest diversity index values indicated the effect of nutrient enrichment and the risk of coastal eutrophication. High dominance of cyanobacteria may also be explicated by climate changes considering its effect in the other areas.

Distributions of total metals in the surface sediments of the Bandirma and Erdek Gulfs, Marmara Sea, Turkey

The aim of this study is to determine the contents of aluminum, iron, manganese, nickel, copper, zinc, chromium, cadmium, lead, and mercury in sediments at 1–30 m depths of the Bandırma and Erdek Gulfs in the Southern Inner Shelf of the Marmara Sea. Sediment samples were collected from different depths (1 m, 5 m, 10 m, 20 m, 30 m) at each region in February 2008. Primary hydrographic conditions, such as temperature (6.6–14.5°C), salinity (22.6–26.875 psu), percentage of dissolved oxygen saturation (35–83 %), and pH (8.0–8.4) were recorded for each sampling point. Moreover the total organic carbon (0.5–2.9%) and the total calcium carbonate contents (0.8–60%) of sediment samples were determined. In surface sediments of both gulfs, Pb (21–62 mg kg−1) and Cd (0.52–0.86 mg kg−1) contents were determined to be higher than the shale average (Pb 20 mg kg−1, Cd 0.2 mg kg−1) while the other metal contents were measured to be lower in general. On the other hand, generally Hg (0.06–1.1 mg kg−1) contents were higher than the shale average (0.3 mg kg−1)at all of the examined stations in the Bandırma Gulf and lower than the shale average in the Erdek Gulf.