Aysun Uğur

Trace metals and 210Po (210Pb) concentrations in mussels (Mytilus galloprovincialis) consumed at western Anatolia.

The mussels (Mytilus galloprovincialis) have been evaluated for their bioavailability as biomonitors of trace and toxic elements in coastal water of western Anatolia. The levels of Fe, Cu, Zn, Pb, Br and Sr in the edible part of mussels were determined using X-ray fluorescence method during the period of September 1999-July 2000. Distribution of 210Po and 210Pb activities were measured by radiometric methods and their ratios were calculated. The activity concentrations of 210Po and 210Pb were found to vary between 52 +/- 6-1,344 +/- 108 and 6 +/- 2-167 +/- 10 Bqkg(-1) dry wt, respectively. The highest values for 210Po and 210Pb were measured in Foca mussels and also observed the highest Fe, Zn and Br concentrations in the same species. 210Po/210Pb activity ratio were derived as between 3.1 and 25.0.

Biomonitoring of 210Po and 210Pb using lichens and mosses around coal-fired power plants in Western Turkey

Mosses and lichens are useful biological indicators of environmental contamination for a variety of metals and radionuclides of both natural and artificial origin. These plants lack a well-developed root system and rely largely on atmospheric deposition for nourishment. Therefore in the study, different lichens (Cladonia convoluta, Cladonia foliacea) and mosses (Homalothecium sericeum, Hypnum lacunosum, Hypnum cupressiforme, Tortella tortuosa, Didymodon acutus, Syntrichia ruralis, Syntrichia intermedia, Pterogonium graciale, Isothecium alopecuroides, Pleurochatae squarrosa) were collected around the Yatağan (Muğla), Soma (Manisa), Seyitömer - Tunçbilek (Kütahya) coal-fired power plants and investigated for potential use as biomonitors for (210)Po and (210)Pb deposition. While the activity concentrations of (210)Po and (210)Pb in lichens are in the ranges of 151 ± 7-593 ± 21 and 97 ± 5-364 ± 13 Bq kg(-1), for mosses the ranges for (210)Po and (210)Pb are 124 ± 5-1125 ± 38 and 113 ± 4-490 ± 17 Bq kg(-1), respectively. In the study, the moss samples were observed to accumulate more (210)Po and (210)Pb compared to lichens. While the most suitable biomonitor was a moss species (H. lacunosum) for Yatağan (Muğla), it was another moss species (S. intermedia) for Soma (Manisa) and Seyitömer - Tunçbilek (Kütahya) sites. (210)Po concentrations were found higher than (210)Pb concentrations at the all sampling stations.

Lichens and mosses for correlation between trace elements and 210Po in the areas near coal-fired power plant at Yatağan, Turkey

The lichensRhizoplaca melanophthalma, Cladonia convoluta, Cladonia pyxidata and the mossesGrimmia pulvinata,Hypnum cupressiforme were analyzed for Pb, Cr, Cd, Co, Ni, Mn, Cu, Zn and Fe using atomic absorption spectrophotometry over a wide area around a coal-fired power plant located in Yatağan. The results were compared with the 210Po concentrations previously measured in the same samples. Correlations between 210Po and trace elements for different moss and lichen species of the same localization and for different localizations for the same species were also studied. In general trace element concentrations do not show significant differences from site to site for all species except Mn in Hypnum cupressiforme and 210Po in Grimmia pulvinata. To discuss the 210Pb level and sources in indicator plants analyzed, also radium contents of surface soil at each sampling station was measured and compared with the average values for similar soil types in the literature.

210Po and 210Pb variations in fish species from the Aegean Sea and the contribution of 210Po to the radiation dose.

In recent years, there has been increasing interest in the significance of natural radionuclides, particularly (210)Po, in the marine environment. (210)Po, a naturally occurring alpha emitter, accumulates in marine organisms and reflects differences in their diets. In the literature, there is no data for (210)Po and (210)Pb activity concentrations for fish species on the Turkish coast of Aegean Sea. Therefore, in this study, multiple fish species were collected from six stations seasonally on the Turkish coast of Aegean Sea and were analyzed for their (210)Po and (210)Pb content. The (210)Po and (210)Pb concentrations in the fish samples were found to vary from undetectable levels to 499 ± 44 Bq kg(-1) dry weight (dw) and from 1.0 ± 0.3 Bq kg(-1) to 35 ± 4.0 Bq kg(-1) (dw), respectively. There were no significant differences in the activity concentrations of (210)Po and (210)Pb in fish samples between seasons (ANOVA, P>0.05). The highest dose contribution of (210)Po to humans was calculated to be 10,530 μSv year(-1).

Spatial and temporal variability of 210Po and 210Pb in mussels (Mytilus galloprovincialis) at the Turkish coast of the Aegean Sea

In this study, the activity concentrations of ²¹⁰Po and ²¹⁰Pb were determined in mussel samples (Mytilus galloprovincialis) collected from the Turkish coast of the Aegean Sea. The samples were collected seasonally for a period of two years (2004-2006) at six coastal stations (Çanakkale, Dikili, Foça, Çeşme, Didim, Bodrum). Mussels were separated into several groups according to their size (1-4,4-6,>6 cm). The results showed that ²¹⁰Po concentrations in mussels varied between 53±4 and 1960±60 Bq kg(-1)dw. The highest activity ²¹⁰Po concentrations were determined in winter samples of mussels with a shell length of 4-6 cm from Didim. In general, it was observed that the ²¹⁰Pb concentration levels in mussels were lower than ²¹⁰Po concentrations. The ²¹⁰Po/²¹⁰Pb activity concentration ratios exceeded unity for all mussel samples and averaged 26.0. The inter-site differences seen in ²¹⁰Po concentrations can be due to both the natural background levels of sites and industrial activities.

Activity levels of 210Po and 210Pb in some fish species of the Izmir Bay (Aegean Sea)

Concentrations of ²¹⁰Po and ²¹⁰Pb were determined in the edible muscle tissue of twelve species of marine fish collected from Izmir Bay in the Aegean Sea Region of Turkey during the 2006-2007. ²¹⁰Po activity concentrations in fish samples were found to vary from ND to 400±9 Bq kg⁻¹ dry weight and ²¹⁰Pb activity concentrations were found to vary from ND to 15±3 Bq kg⁻¹ dry weight. The highest dose contribution due to ²¹⁰Po to humans was found to be 8.908 μSv y⁻¹.

Radiometric dating of sediment cores from a hydrothermal vent zone off Milos Island in the Aegean Sea

Sediment cores from a hydrothermal vent zone off Milos Island in the Aegean Sea were dated using the 210Pb method. The average unsupported 210Pb inventory in the cores was calculated to be 3256 Bq m(-2). The corresponding mean annual 210Pb flux of 105 Bq m(-2) year(-1) is comparable to estimates of the atmospheric flux given in the literature. 210Pb fluxes calculated from the unsupported 210Pb inventories in cores are also comparable with the 210Pb vertical fluxes determined from settling particles off the coast of Milos Island. The highest unsupported 210Pb concentrations (89 Bq kg(-1)) were measured in the sediments nearest to the hydrothermal vent area suggesting that the sedimentation rate is lowest at this site. Direct gamma measurements of 210Pb were used to date three sediment cores that are located at different distances from the vent zone: one is in the immediate vicinity of the vent; and others are outside the zone. Sedimentation rates for these cores, calculated using the CRS and CIC models, ranged from 0.088+/-0.008 cm year(-1) to 0.14+/-0.01 cm year(-1). Where both models were applicable, the results given by the two methods were in good agreement. 137Cs concentrations in all three cores generally declined with depth but showed no clear signal of either the period of maximum fallout from weapons testing or the Chernobyl accident. 210Po activities were also measured and the maximum 210Po concentration was in the sediment surface layer (166 Bq kg(-1)).

Sorption kinetics of cesium on ZrO2 and ZrO2-SiO2-TiO2 microspheres

Abstract ZrO2 and ZrO2-SiO2-TiO2 (with 1:1:1 mol ratio) microspheres have been prepared by the sol-gel method and characterized to study the sorption kinetics of cesium. The effect of pH on the adsorption capacity was determined for both type sorbents and the maximum adsorption percentage of cesium was observed at pH 10. To elucidate the kinetics of the ion-exchange reaction on pure and ternary oxide microspheres, the isotopic exchange rates of cesium ions between both types of sorbent microspheres and aqueous solution were measured radiochemically and compared with each other. The diffusion coefficients of Cs+ ion for ZrO2 and ZrO2-SiO2-TiO2 sorbent microspheres at pH 10 were calculated as 3.648×10−8 m2 s−1 and 6.383×10−8 m2 s−1, respectively, under particle diffusion controlled conditions.

Plutonium isotopes, 241Am and 137Cs activity concentrations in marine sediments of Gökova Bay, Aegean Turkish Coast

Samples of marine surface sediments of different grain sizes collected in Gökova, a small bay on the Aegean Turkish Coast, have been examined to measure alpha- and gamma-radioactivity. The purpose of this research is to define a baseline study of man-made radionuclides on sediments along Gökova Bay, using a combination of direct gamma-spectrometry, radiochemical separation and alpha spectrometry. The analysis of these samples revealed measurable quantities of some artificial radionuclides namely: 239+240Pu (from 0.13±0.017 to 0.85±0.15 Bq.kg–1). 137Cs, 241Am and 238Pu were identified at a very low level. Concentration ratios of 238Pu to 239+240Pu obtained seem to confirm that this artificial radioactivity is due mainly to Chernobyl accident.

Determination Of Lead-210 And Polonium-210 In Marine Environment

Naturally occurring 210 Pb and 210 Po are important tracers used in marine environment studies. In this study, 210 Po and 210 Pb measurements in marine samples (sediment, sea water and biota) were performed using alpha spectrometry. Chemical recoveries are obtained using 209 Po tracer. Two different approaches for 210 Pb determinations are also compared. First, to keep the original samples for about 1 year to eliminate the excess 210 Po and to reach 210 Po- 210 Pb equilibrium before radiochemical separation of 210 Po. The second is to extract the excess 210 Po in the samples, then wait for attaining 210 Pb- 210 Po equilibrium in the solution to obtain 210 Pb activities. In samples, time corrections for excess 210 Po originated from radioactive decay of grand parent are discussed.