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RADIONUCLIDE POLLUTION DUE TO FERTILIZER USE IN SOME SALINE SOILS OF THE PUNJAB AND THEIR POTENTIAL RISK ASSESSMENT ON HUMAN HEALTH

AKHTAR, NASIM (2006) RADIONUCLIDE POLLUTION DUE TO FERTILIZER USE IN SOME SALINE SOILS OF THE PUNJAB AND THEIR POTENTIAL RISK ASSESSMENT ON HUMAN HEALTH. PhD thesis, Bahauddin Zakariya University, Multan.

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Abstract

Natural radioactivity due to40K, 232Th and 137Cs were measured in saline and normal soils aided with fertilizers. Then food crops grown in saline and normal soils and their risk on human health will be assessed. Soil Sampling was done in two saline soils of Biosaline Research Station-I (BSRS-I) 40 km from Lahore and Biosaline Research Station-II (BSRS-II), Pacca Anna 34 km from Faisalabad and soil of nuclear Institute for Agriculture and Biology (NIAB) Faisalabad, was taken as normal soil. The selected patches have different elevations, rainfalls, textures etc. Those were analyzed for radioactive contamination of the natural uranium and thorium series, 40K and fission fragment137 Cs. The entrance of these radionuclide in food chain of human being through dietary crops grown in these soils aided by Phosphatic fertilizers was studied by growing the wheat crop on the study sites. Gamma ray spectroscopy technique was used to study the natural radioactivity. Activity concentration of the concerned radionuclides for the site 1 (NIAB) soil was as232 Th, 57.18 Bqkg-1 226Ra, 34.45 Bqkg-1 40K, 643.60 Bqkg-1 and 137Cs, 2.26 Bqkg-1. Site 2 contained radiation levels, as: 226Ra, 29.99 Bqkg-1 and 232Th came as 45.52Bqkg-1. 40K, 597.50 Bq kg-1 and 137Cs was not found. In the Biosaline research station-II barren/ virgin and fertilized saline soils of Pacca Anna, the average concentrations of the concerned radionuclides for both type of the soils were as follows: 40K, for barren/virgin cultivated saline soil was 563.96 Bq kg-1 550.08 respectively; 226Ra, 26.40 and 20.96 Bq kg-1, and 232Th, 49.38 and 42.68 Bq kg-1 137CS, 3.25 and 1.50 Bq kg-1 respectively. Activity mass concentrations of 238U ( 226Ra) in the rock phosphate from Jordan and Pakistan were 428 and 799 Bq kg-1, respectively The activity in the triple-superphosphate fertilizer was 701 Bq kg-1, which was greater than the average values of 226Ra for other types of phosphate fertilizers under study. The radioactive mineral analysis in soil, rock, fertilizers and foodstuff were done by XRD technique. The radioactive minerals identified most frequntly in rock phosphate were uranopilite, uranophane, ekanite, autonite and thorogummite. The minerals found in less frequency were uramphite, andersonite, uranite, uranocircite, charalite, chermikvite and sharpite. The soil of site- 1 contained greater number of minerals urinate, uramphite, thorogummite, zeppeite, ca1ciouranoite, andersonite and uranophane. The soil of site- 2 contained andersonite, calciouranoite, zeppeite, throgummite, uramphite and urinate. The radioactive minerals detected in site - 3 were uramphite, throgummite, zeppeite and calciouranoite.Minerals identified in site - 4 were less in number, It contained only throgummite and calciouranoite. Ingestion dose due to each radionuclide has been calculated as 206.1, 185.2, 177.9 and 146.3 µ Sv y-1 from all study sites (1-4) respectively. Radium equivalent activity, external and internal hazards for site-l were found as 165.62, 0.438 and 0.484 respectively. The absorbed dose in air for site- 2 was 67.70 nGy h-1. The annual effective doses for site - 2 saline patch calculated were 0.223 mSvy-1. The Radium equivalent activity and external and internal hazard index for site- 3 saline farms were found as 155.34 Bq Kg-1, 0.4117 and o.223 respectively. The transfer factors of the natural radionuclides from soil to wheat grain have been determined as: (3-20)xl0-3 for 226Ra, (1-20)xl0-2 for232 Th and (1-2)xl0-2 for 40K. Soil-to-grain values ranged from 3.1 to 3.78 % for 226Ra and from 2.18 to 2.9 % for 232Th whereas for 40K the range was from 18 to 20.4 %. The percentage uptake of radioactivity from soil-to-root and soil-to-shoot of wheat are 60% and 17% respectively, from all the four selected soils. The Risk assessment was made on the basis of daily consumption of wheat as chapatti, bread, nan and rusk used as food items of human beings. If the wheat food consumed is from the unfertilized fields of site-4, then the risk coefficient was minimum. If we subtract the value of excess cancer risk from barren soil, which is 4 persons in 1 million. The net excess cancer risk from the Faisalabad soil (site-I) is maximum, which is 58 persons in one million. The net excess cancer risk from Lahore saline soil (site-2) is 53 in 1 million. On the basis of data, it is concluded that excess risk per year was maximum due to the external exposure and the consumption of wheat foodstuff grown on the highly fertilized soils (sites 1-2).

Item Type:Thesis (PhD)
Subjects:Physical Sciences (f) > Physics(f1)
ID Code:2585
Deposited By:Mr. Javed Memon
Deposited On:07 Jul 2009 13:05
Last Modified:07 Jul 2009 13:05

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