Toprak Gazında Bir Toron Anomalisi: Büyükorhan, Bursa, Türkiye'den Bir Vaka Çalışması

İnsanların maruz kaldıkları ana radyasyona kaynakları, kayalardan ve topraktan salınan radon, toron ve bunların bozunma ürünlerinin solunması ve yersel gama radyasyonudur. İnsanlar üzerindeki olası etkilerini tahmin etmek için, granitoyid biriminin geniş bir alanı kapladığı Bursa'nın güneyindeki Büyükorhan'da 18 farklı lokasyonda toprak gazındaki radon ve toron konsantrasyonları, yeraltı sularındaki radon ölçümleri ve dış mekan gama doz oranları ölçülmüştür. Toprak gazındaki radon konsantrasyonlarının 0,54 ± 0,01 kBq m−3 ile 36,25 ± 0,98 kBq m−3 (ortalama değer 11,54 ± 2,79 kBq m−3) arasında ve toron konsantrasyonlarının 14,86 ± 1,21 kBq m−3 ile 1462.50 ± 26.47 kBq m−3 (ortalama değer 174.53 ± 87.35 kBq m−3) arasında değiştiği bulunmuştur. Yeraltı suyu numunelerinde ölçülen radon konsantrasyonları 6.89 ± 1.11 Bq l-1 ile 61.43 ± 0.55 Bq l-1 (ortalama değer 24.85 ± 4.36 Bq l-1) arasında değişmektedir. Ölçülen dış mekan gama doz oranları ise 68 nGy h-1 ile 369 nGy h-1 (ortalama değer 129.7 nGy h-1) arasında değişmektedir. Bölgenin litolojisinin, toprak gazındaki radon ve toron konsantrasyonları üzerinde etkili olduğu görülmüştür. Ayrıca bu çalışmada, toprak gazındaki radon ve toron konsantrasyonlarının dış mekan gama doz oranları üzerindeki etkisi de belirtilmiştir.

A Thoron Anomaly in the Soil Gas: A Case Study From Büyükorhan, Bursa, Turkey

The main sources of radiation exposure are the inhalation of radon, thoron and their decay products released from the rocks and soil, and terrestrial gamma radiation. In order to estimate the potential effects, the radon and thoron concentrations in the soil gas, the radon measurements in the groundwaters and outdoor gamma dose rates were measured at 18 different locations in Büyükorhan in the south of Bursa, which granitoid unit takes up a vast space in this area. The radon and thoron concentrations in the soil gas were found to vary from 0.54 ± 0.01 kBq m−3 to 36.25 ± 0.98 kBq m−3 (mean value 11.54 ± 2.79 kBq m−3) and from 14.86 ± 1.21 kBq m−3 to 1462.50 ± 26.47 kBq m−3 (mean value 174.53 ± 87.35 kBq m−3), respectively. The measured radon concentrations in the groundwater samples ranged from 6.89 ± 1.11 to 61.43 ± 0.55 Bq l-1 (mean value 24.85 ± 4.36 Bq l-1). The measured outdoor gamma dose rates varied from 68 nGy h-1 to 369 nGy h-1 (mean value 129.7 nGy h-1).It was observed that radon and thoron concentrations in the soil gas are controlled by the lithology of the region. Additionally, the effect of the radon and thoron concentration in soil gas on outdoor gamma dose rate is indicated in the present study.

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