Sayhan Topcuoğlu

137Cs baseline levels in the Mediterranean and Black Sea: A cross-basin survey of the CIESM Mediterranean Mussel Watch programme

The common mussel Mytilus galloprovincialis was selected as unique biomonitor species to implement a regional monitoring programme, the CIESM Mediterranean Mussel Watch (MMW), in the Mediterranean and Black Seas. As of today, and upon standardization of the methodological approach, the MMW Network has been able to quantify (137)Cs levels in mussels from 60 coastal stations and to produce the first distribution map of this artificial radionuclide at the scale of the entire Mediterranean and Black Seas. While measured (137)Cs levels were found to be very low (usually < 1 Bq kg(-1) wet wt) (137)Cs activity concentrations in the Black Sea and North Aegean Sea were up to two orders of magnitude higher than those in the western Mediterranean Basin. Such effects, far from representing a threat to human populations or the environment, reflect a persistent signature of the Chernobyl fallout in this area.

The natural depuration rate of 137Cs radionuclides in a lichen and moss species

Abstract Caesium-137 concentrations in lichen and moss samples have been studied for calculations of natural depuration rates. The lichen and moss species were collected from the same trees in western and eastern Black Sea region during the periods of 1987–1992 and 1990–1993, respectively. The natural depuration rates are estimated at biological half-lives. The pattern of depuration results represented by a single component for each non-vascular plant. The biological half-lives of 137 Cs in a lichen and moss samples ( Xanthoria parietina and Leucodon immersus ) are estimated to be 58.6 and 10.9 months, respectively. This work set supports the view that radioactivity monitoring in lichens can be a more useful monitor than mosses to determine the lasting effect of radioactive fallout.

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.

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.

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.