Gökova Körfezi deniz sediment kodlarında radyoaktif Pb, Po, Ra, CsAm ve Pu izotoplarının dağılımının incelenmesi, sedimentasyon hızı ve tarihleme çalışmalarında kullanılması
Küçük Resim Yok
Tarih
1998
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Ege Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
IV ÖZET GÖKOVA KÖRFEZİ DENİZ SEDİMENT KORLARINDA RADYOAKTİF Pb, Po, Ra, Cs, Am ve Pu İZOTOPLARININ DAĞILIMININ İNCELENMESİ, SEDİMENTASYON HIZI VE TARİHLEME ÇALIŞMALARINDA KULLANILMASI TANBAY (UĞUR), Aysun Doktora Tezi, Nükleer Bilimler Anabilim Dalı (Fizik) Tez Yöneticisi: Prof.Dr. Güngör YENER 1998,231 Sayfa Çalışmada deniz sedimentlerinde sedimentasyon hızı ve yaş tayinine yönelik olarak gama ve alfa spektroskopisi bir arada kullanılmış ve tarihleme için 210Pb aktivitelerine dayanan matematiksel modellerin uygulanması araştırılmıştır. Ege Denizi'nin ülkemiz sulannda bugüne dek bu tür bir çalışmanın yapılmamış olması nedeni ile geniş kapsamlı bir araştırma başlatmak amaçlanmış ve konumunun önemi dikkate alınarak çalışma alanı olarak Gökova Körfezi seçilmiştir. Gökova Körfezi'nde 7 istasyondan, 100-150m derinlikten "gravity corer" ile toplanan deniz sedimenti kor örneklerinde, porozite ve kütle derinliği hesaplan için yaş ve kuru ağırlıkları tayin edilmiş, doğal (210Po, 210Pb, 226Ra ve 232Th) ve yapay (137Cs, 239-240Pu, ^Pu ve 241Am) radyonüküdlerin dağılımlan incelenmiştir. Doğal radyonüklidlerden 226Ra ve ^^'un, yapay radyonüklidlerden 137Cs'un tayinleri, sintilasyon ve yan iletken gama spektroskopileri ile, 210Po'un tayinleri ise radyokimyasal depozisyonla gümüş diskler üzerinde toplanarak alfa spektroskopisi ile yapılmıştır. Transuranik radyonüklidler ise çelik diskler üzerine elektrokimyasal depozisyonla toplanmış ve yine alfa spektroskopisi ile ölçülmüştür.Radyoaktif denge durandan göz önüne alınarak 210Po aktivitelerinden, 210Pb aktivitelerine geçilmiştir. Deniz sedimenti kor örneklerinde aktivite konsantrasyonu aralıkları 210Pb için 1.37+0.08- 6.72±0.26dpm/g olarak ve ^"Tta için 1.15±0.32-2.38±0.667dpm/g olarak bulunmuştur. Denge ve dengenin üzerindeki aktiviteler hesaplanarak Gökova Körfezi Deniz sedimentleri için sedimentasyon hızı ve yaş tayinleri çalışmaları yapılmıştır. Yapay radyonüklidlerden 137Cs aktivitesi tüm kor örneklerinde deteksiyon limitinin altında kalmıştır. 239-240pu aktivite aralığı ise 0.13±0.017- 0.85±0.15Bq/kg olarak saptanmış ve maksimium ^Pu düzeyi 0.09±0.02Bq/kg ve 24IAm 0.33±0.05Bq/kg olarak bulunmuştur. Anahtar Sözcükler: 210Po, 210Pb, sedimentasyon hızı, yaş tayini
ABSTRACT INVESTIGATION OF DISTRIBUTIONS OF RADIOACTIVE Pb, Po, Ra, Cs, Am and Po ISOTOPES IN MARINE SEDIMENT CORES OF GÖKOVA BAY AND THEIR USE IN SEDIMENTATION RATE AND DATING TANBAY (U?UR), Aysun Ph.D. Thesis, Nuclear Science (Physics) Supervisor: Prof. Dr. Güngör YENER 1998, 231 pages In this Ph.D. thesis, gamma and alpha spectroscopy are both used for determination of sedimentation rate and dating marine sediment cores and the application of several mathematical models based on 2,0Pb activities to calculate the age of the sediments are investigated. There is not any work done in Turkish coastalzone of the Aegean Sea on scavenging, sedimentation rate and dating and also on radioactive lead distrubitions. This proposed work will be the first step for a large scale research on the subject. Because of the importance of its location, Gökova Bay has been chosen as the working area. Marine sediment cores from seven stations at Gökova Bay were recovered at 100-150m depth, using a gravity corer. Their dry weights were measured and these values together with wet weights were used to calculate porosities and mass depths. The natural and man-made radionuclide distributions were investigated within the seabed marine sediment cores. 210Pb, 226Ra and 137Cs were measured by scintillation and semiconductor gamma spectroscopy. 210Po was measured by alpha spectroscopy after spontaneous deposition on silver discs. Transuranics were also measured by alpha spectroscopy after electrochemical deposition on stainless steel discs. It has been assumed that there exists radioactive equilibrium in uranium series radionuclides in sediment core samples and so 2I0Pb activities were calculatedusing To activities. Sediment sample activity concentration ranges of Pb and 226Ra were calculated as 1.37+0.08-6.72±0.26dpm/g and as 1.15+0.32- 2.38±0.667dpm/g respectively. The sediment acumulations rates and the age of each layer was estimated using "supported" and "unsupported" activity concentrations of 210Pb. As the artificial radionuclides, 137Cs for all sediment cores samples were under detection limit. The activity concentrations of the ^ 240Pu were observed to be in the range of 0. 13+0.017-0.85+0. 15Bq/kg. 241Am and S8Pu were identified at a very low level. Keywords: 210Po, 210Pb, Sedimentation rate, Dating.
ABSTRACT INVESTIGATION OF DISTRIBUTIONS OF RADIOACTIVE Pb, Po, Ra, Cs, Am and Po ISOTOPES IN MARINE SEDIMENT CORES OF GÖKOVA BAY AND THEIR USE IN SEDIMENTATION RATE AND DATING TANBAY (U?UR), Aysun Ph.D. Thesis, Nuclear Science (Physics) Supervisor: Prof. Dr. Güngör YENER 1998, 231 pages In this Ph.D. thesis, gamma and alpha spectroscopy are both used for determination of sedimentation rate and dating marine sediment cores and the application of several mathematical models based on 2,0Pb activities to calculate the age of the sediments are investigated. There is not any work done in Turkish coastalzone of the Aegean Sea on scavenging, sedimentation rate and dating and also on radioactive lead distrubitions. This proposed work will be the first step for a large scale research on the subject. Because of the importance of its location, Gökova Bay has been chosen as the working area. Marine sediment cores from seven stations at Gökova Bay were recovered at 100-150m depth, using a gravity corer. Their dry weights were measured and these values together with wet weights were used to calculate porosities and mass depths. The natural and man-made radionuclide distributions were investigated within the seabed marine sediment cores. 210Pb, 226Ra and 137Cs were measured by scintillation and semiconductor gamma spectroscopy. 210Po was measured by alpha spectroscopy after spontaneous deposition on silver discs. Transuranics were also measured by alpha spectroscopy after electrochemical deposition on stainless steel discs. It has been assumed that there exists radioactive equilibrium in uranium series radionuclides in sediment core samples and so 2I0Pb activities were calculatedusing To activities. Sediment sample activity concentration ranges of Pb and 226Ra were calculated as 1.37+0.08-6.72±0.26dpm/g and as 1.15+0.32- 2.38±0.667dpm/g respectively. The sediment acumulations rates and the age of each layer was estimated using "supported" and "unsupported" activity concentrations of 210Pb. As the artificial radionuclides, 137Cs for all sediment cores samples were under detection limit. The activity concentrations of the ^ 240Pu were observed to be in the range of 0. 13+0.017-0.85+0. 15Bq/kg. 241Am and S8Pu were identified at a very low level. Keywords: 210Po, 210Pb, Sedimentation rate, Dating.
Açıklama
Anahtar Kelimeler
Nükleer Mühendislik, Nuclear Engineering, Gökova Körfezi, Gökova Bay, Kurşun, Lead, Polonyum, Polonium, Yaş tayini, Age determination, Çökeltme, Sedimentation, İzotoplar, Isotopes
