Pengukuran dan perbandingan paras kepekatan 222rn dalam tanahmengikut siri dan tekstur tanahdi kawasan Seberang Perai Utara, Pulau Pinang

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Date
2007
Authors
Siti Aishah, Ar. Azmi
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Abstract
222Rn is a naturally occurring radioactive noble gas, originating from the decay of uranium, 238U, in rocks, soils and minerals. 222Rn and its solid decay products are responsible for about 50% of the annual natural radiation dose of the population. The purpose of this study is to measure the 222Rn concentration in soils especially sand, silt and clay samples and relate it to relative humidity and soil particle size. This study also measured the 222Rn concentration in three levels of 222Rn concentration (high risk, medium risk and low risk), 6 types of soil texture, 6 soil series and three geological formations. The soil samples were taken from 111 sites in the area of Seberang Perai Utara, Penang at 30 cm below the soil surface. The 222Rn concentrations were measured using the continuous active sampling method. The particle size distribution of the soil was determined using the sieve and pipette methods. The study shows that the 222Rn concentration is controlled by relative humidity and soil particle size. The 222Rn concentration values vary from 1.2 pCi/l to 10.9 pCi/l. The highest level of 222Rn concentration was found at Kg. Ekor Kucing area, while the lowest was from the Kg. Paya Keladi area. There is a positive correlation between relative humidity and 222Rn concentration with a correlation coefficient value at 0.76. There is also a positive correlation between clay content and 222Rn concentration with a correlation coefficient value at 0.21. The relation between sand content and 222Rn concentration shown by negative correlation coefficient value at -0.22. Whereas the result show there is no relationship between silt content and 222Rn concentration which shown by correlation value at 0.02. The results show that for 222Rn concentration range of < 2pCi/l, the 222Rn concentration mean was 1.6 pCi/l, whereas for 222Rn concentration ranges of ≥ 2 pCi/l and < 4 pCi/l, and ≥ 4 pCi/l, the 222Rn concentration means were 2.9 pCi/l and 6.1 pCi/l respectively. The results also show that the highest value of 222Rn concentration mean in relation to soil texture, recorded by silty clay, was 4.3 pCi/l whereas the others were sandy clay (4.2 pCi/l), clay (4.1 pCi/l), silt loam (3.7 pCi/l), clay loam (2.8 pCi/l) and sandy loam (2.2 pCi/l). The highest value of 222Rn concentration mean in relation to soil series was recorded by the Telemong-Akob-Local Aluvium series at 4.3 pCi/l. Other findings were for the Sogomana-Sitiawan-Manik series (4.0 pCi/l), Sedu-Parit Botak- Linau series (2.6 pCi/l), Chengai series (4.1 pCi/l), Holyrood-Lunas series (3.2 pCi/l) and Kranji series (2.1 pCi/l). The results also show that the highest value of 222Rn concentration mean in relation to formations was recorded by Beruas Formation (4.3 pCi/l), whereas the Gula Formation show the lowest value of 222Rn concentration mean (3.5 pCi/l). The Simpang Formation had a 222Rn concentration mean of about 3.8 pCi/l.
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Master
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Science Physic
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