External gamma radiation levels and natural radioactivity in soil around a phosphate fertilizer plant at Mumbai

Fertilizers containing phosphate have been used worldwide in increasing quantities in order to replenish natural nutrients, which are being continuously depleted from the soil by virtue of farming activities. Phosphate rocks together with potassium ores and nitrogenous compounds are the main raw materials used for industrial fertilizer production. Rock phosphate ore processing and disposal of phosphogypsum contribute to enhanced levels of natural radionuclides in the environment. The levels of naturally occurring radionuclides such as U-238, Th-232, Ra-226 and K-40 in soil samples collected around a phosphate fertilizer plant were estimated. Radium equivalent activity, external hazard index and external dose rate due to natural gamma background at various locations around the plant were also measured.