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ملخص البحث |
It has become a need and a tool used around the world to apply inorganic fertilizers to treat crop soil and improve its yield. There are varying concentrations of uranium and thorium in these fertilizers. Therefore, due to the high use of fertilizer in agriculture, lots of radionuclides of the natural radioactive series 238U, 235U and 232Th are dispersed into the environment. In this work, the radioactivity levels were determined in five samples of three types of fertilizers (Triple superphosphate-46% (TSP), Nitrogen, Phosphorus, and Potassium (NPK), Potassium sulfate (SOP)) were imported from four countries and were available in local markets. In addition, eleven samples of soils from ten localities in Middle Governorate of Gaza Strip, Palestine were analyzed to determine the radioactivity levels using the sealed-cup technique and CR-39 detectors.
The radioactivity concentration levels in fertilizers were used in agricultural lands for cultivation had the maximum radon concentration 1099 Bq/m3 and effective radium 8.7 Bq/kg, with exhalation rate 1108 mBq/m2h from the NPK from Jordan. While the minimum radon concentration, effective radium, and exhalation rate values were found to be 304 Bq/m3, 1.81 Bq/kg, and 308 mBq/m2h respectively in SOP fertilizer made in China.
The soil in the study area were classified into two main textural classes, the sandy loam and loamy sand. In the sandy loam the radon concentration levels in the sandy loam class range from 970.10 to 2295.73 Bq/m3 and effective radium 6.66 to 17.13 Bq/kg, with exhalation rate 0.98 to 2.315 mBq/m2h, whereas in the loamy sand were 538.25 to 1823.78 Bq/m3, 3.18 to 11.34 Bq/kg, and 0.545 to 1.84 mBq/m2h respectively. The radioactivity concentration were higher in the sandy loam class due the their finer texture contents (silt and clay) comparing with loamy sand class. Additionally, this study found that the higher concentration levels referred to high contents of organic matter and water contents in the soil samples.
Keywords: radon concentration, pollution, fertilizer, soil, Gaza Strip
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