Yavuz Çotuk

Radioactivity concentrations in topsoil samples from the Thrace region of Turkey and assessment of radiological hazard

The activity concentrations of gamma emitting radionuclides were measured in surface soil samples from the Thrace region. 232Th, 238U, 226Ra, 40K and 137Cs activities and physico-chemical parameters of the soil samples were determined in samples collected from 73 sampling stations. Radionuclide concentrations measured were compared with those found in the samples from other locations of Turkey and from different countries. The average activity concentrations of 232Th, 238U, 226Ra, 40K and 137Cs were found to be 24.71 ± 8.79, 22.30 ± 7.93, 32.09±12.44, 509.00±160.05, 32.74±29.24 Bq kg−1, respectively. The mean value of the annual effective dose equivalent from the outdoor terrestrial gamma radiation was calculated as 57.2 μ Sv.

Assessment of metal concentrations in indigenous and caged mussels (Mytilus galloprovincialis) on entire Turkish coastline.

This survey was conducted to determine metal concentrations in the biomonitor organism Mytilus galloprovincialis collected from all coasts of Turkey. Naturally-occurring mussels were gathered along the coast of the Black Sea, Sea of Marmara, Bosphorus and Aegean Sea, while a 6-month transplantation session was implemented on the Levantine Sea coast where M. galloprovincialis does not adapt naturally. Mussels collected from the Izmir area were employed for transplantation to five locations along the Levantine Sea coast of Turkey. Concentrations of Ag, Al, As, Cd, Co, Cr, Cu, Fe, K, Mn, Ni, Pb, Sn, V, and Zn were measured using ICP-MS (Inductively Coupled Plasma-Mass Spectrometry). Results showed that concentrations of some essential elements (Co, Fe, K, Mn, Zn) generally fell within the range of acceptable global values. However, at some sampling sites the metal concentrations were found at higher levels compared to the world average and recommended limits. For instance, very high Ag and Cu concentrations were observed in mussel caged at Yumurtalık. Elevated As, Ni, Pb, and V concentrations were observed at the Tirebolu, Ereğli, Eskihisar, and Tekirdağ locations, respectively. Taking into account all measured metals, it can be inferred that Yumurtalık is the most metal-contaminated locality. The results highlighted metal-specific pollution at coastal areas in each sea cover Turkey. In spite of the high metal levels estimated daily intakes (EDI) of the measured elements were well below through very low mussel consumption by Turkish public.

Radioactivity concentrations in mussel (Mytilus galloprovincialis) of Turkish Sea coast and contribution of 210Po to the radiation dose

Radionuclides levels were determined in indigenous and transplanted mussels (Mytilus galloprovincialis) collected from Turkish marine environment. Radioactivity concentrations of ¹³⁷Cs, ⁴⁰K, ²²⁶Ra, ²²⁸Ra, ²¹⁰Po and ²¹⁰Pb were determined in the soft tissues of the mussel samples collected in Bosphorus Strait, Coasts of Black Sea, Marmara Sea and Aegean Sea. Mussel transplantation was carried out by using mussel cages in Levantine Sea coast since M. galloprovincialis did not naturally adapt along the coast. The average activity concentrations of ¹³⁷Cs, ⁴⁰K, ²²⁶Ra, ²²⁸Ra, ²¹⁰Po and ²¹⁰Pb in the coastline of Turkey were found to be 0.7±0.1, 469±24, 0.9±0.1, 1.0±0.1, 122±4 and 10.9±0.9 Bq kg⁻¹ in dry weight (dw), respectively. The average of ²¹⁰Po/²¹⁰Pb ratio was found to be ∼14. Total annual effective ²¹⁰Po dose was calculated to be in the range of 0.25-3.30 μSv due to mussel consumption. Radioactivity and dose levels were compared with those of similar studies carried out in Mediterranean countries.

232Th, 238U, 40K, 137Cs radioactivity concentrations and 137Cs dose rate in Turkish market tea

In this study, the activity concentrations of 232Th, 238U, 40K and 137Cs were measured in 10 branded tea samples from local Turkish markets using gamma spectrometry with an HPGe detector. The mean activity concentrations of 232Th, 238U, 40K and 137Cs were found to be 2.7 ± 1.0, 0.9 ± 0.4, 501 ± 42 and 45.04 ± 2.6 Bq kg−1, respectively. The average annual effective 137Cs dose as a consequence of tea consumption was found to be 385 nSv for an adult person, which is not hazardous to public health. The correlation coefficient between 137Cs and 40K was found to be−0.82 in these samples. The present data were compared with those found in other studies.

Natural and artificial radionuclide activity concentrations in surface sediments of Izmit Bay, Turkey.

Surface sediments from the north-eastern coast of the Marmara Sea, Turkeys most industrialized coastal region, were enriched with radioisotopes from the Chernobyl explosion in 1986. Caesium-137 in these sediments is also thought to originate from one former paper mill located nearby that used wood contaminated by Chernobyl explosion-originated (137)Cs for paper production. The average activity concentration of the (137)Cs was 21 Bq kg(-1), while naturally occurring radioisotopes, i.e. (40)K, (226)Ra, and (228)Ra, were 568, 18 and 24 Bq kg(-1), respectively, in surface sediments. The natural radionuclide activities reached their highest levels near petrochemical, phosphate and fertilizer processing facilities. Average (137)Cs activities were generally up to ten times higher than in Middle Eastern marine sediments and lower than those in Northern European sediments.

Radioactivity measurements in moss (Hypnum cupressiforme) and lichen (Cladonia rangiformis) samples collected from Marmara region of Turkey

The present study was conducted to compare the (137)Cs, (40)K, (232)Th, and (238)U activity concentrations in epigeic moss (Hypnum cupressiforme) and lichen (Cladonia rangiformis). The activity levels in 37 moss and 38 lichen samples collected from the Marmara region of Turkey were measured using a gamma spectrometer equipped with a high purity germanium (HPGe) detector. The activity concentrations of (137)Cs, (40)K, (232)Th, and (238)U in the moss samples were found to be in the range of 0.36-8.13, 17.1-181.1, 1.51-6.17, and 0.87-6.70 Bq kg(-1) respectively, while these values were below detection limit (BDL)-4.32, 16.6-240.0, 1.32-6.47, and BDL-3.57 Bq kg(-1) respectively in lichen. The average moss/lichen activity ratios of (137)Cs, (40)K, (232)Th, and (238)U were found to be 1.32 +/- 0.57, 2.79 +/- 1.67, 2.11 +/- 0.82, and 2.19 +/- 1.02, respectively. Very low (137)Cs concentrations were observed in moss and lichen samples compared to soil samples collected from the same locations in a previous study. Seasonal variations of the measured radionuclide activities were also examined in the three sampling stations.

The usability of tree barks as long term biomonitors of atmospheric radionuclide deposition

In view of the lower radionuclide activities of moss and lichen, tree barks can be used as biomonitors of radioactive contamination, regardless of the contribution of soil uptake. The present study was conducted to determine the activity concentrations of (137)Cs, (40)K, (232)Th and (238)U in the barks of pine (Pinus nigra) and oak (Quercus petraea) trees collected from the Thrace region in Turkey. By considering the previous studies carried out in the same region, it is noticed that among lichen, moss, oak bark and pine bark, oak bark is the best accumulator of (137)Cs and natural radionuclides.