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.
Description
Master
Keywords
Science Physic