Gross alpha, gross beta and activity concentration of 226 Ra in some fertilizers commonly used in the south of Vietnam and health risk due to radionuclides transferred from fertilizers to food crops Thang Nguyen Van 1 • Ba Vu Ngoc 1 • Thu Huynh Nguyen Phong 1 • Hao Le Cong 1,2 • Loan Truong Thi Hong 1,2 Received: 19 February 2018 Ó Akade´miai Kiado´, Budapest, Hungary 2018 Abstract Twelve types of chemical fertilizers commonly used in the south of Vietnam were collected for analysis. It was found that the activity concentration of 226 Ra was in the range from below detectable level (BDL) to 139 Bq kg -1 while gross alpha and gross beta activities were in the ranges from BDL—691 Bq kg -1 and BDL—18753 Bq kg -1 respectively. The correlation was found between gross alpha activity and activity concentration of 226 Ra in most of fertilizers. The radio- logical hazard due to application of fertilizers is insignificantly under the agricultural conditions. Keywords Gross alpha activity  Gross beta activity  Annual effective dose  Transfer factor soil-to-plant  Phosphate fertilizer Introduction Fertilizers are added during the plant growth period in order to enhance the quality of food crops. The usage of fertilizers depend on the type of soil, the type of plant, the part of plant used, and the certain periods of the crop. According to the origins, the fertilizers can be divided into two types: (1) manure fertilizers which are from the products of plants and animals, and (2) chemical fertilizers (hereafter fertilizers) which are from the products of industrial production [1]. In over the world, many types of fertilizers are used popularly, but they can be separated into four types: N (nitrogen), P (phosphor in P 2 O 5 ), K (potas- sium in K 2 O), and NPK (the compound of N, P and K). Fertilizers affect to human health because they contain many toxicity elements including radionuclides. Most of radionuclides existing in fertilizers are natural radionu- clides. They are from uranium series ( 235 U and 238 U), thorium series ( 232 Th), and potassium ( 40 K) as main part of fertilizers [2]. Phosphate rock is the major source for the production of most of phosphate fertilizers in the world. Grade of phosphate rock containing P 2 O 5 varies from 25 to 37%; higher content of P 2 O 5 is desirable for commercial production of the phosphate rich fertilizer [3]. Many studies found that phosphate fertilizers contain a significant amount of natural radionuclides because phosphate rock is the main source of phosphate for the fertilizer industry [2–4]. The various phosphate rocks are well known for their elevated levels of natural radionuclides. For example, the typical activities for sedimentary phosphate rock types are between 1500 and 1700 Bq kg -1 for the 238 U decay chain, often in equilibrium [5]. K fertilizers are produced from K 2 O in which abundance of 40 K is quite significant. 40 K is also the beta emitting radionuclides which is most popular in the earth. N fertilizers are the form of saltpetre such as NH 4 NO 3 , NH 4 Cl, (NH 4 ) 2 SO 4 and (NH 2 ) 2 CO. Due to the production sources, the activity concentration of N fertilizers is insignificant in comparison with others. Beside main components as mention above, many elements were found in chemical fertilizers as a results of production technology. A lot of supplementary materials which con- tain nutrient elements such as calcium (Ca), magnesium & Thang Nguyen Van nvthang@hcmus.edu.vn 1 Nuclear Technique Laboratory, VNUHCM-University of Science, 227 Nguyen Van Cu Street, District 5, Ho Chi Minh City, Vietnam 2 Department of Nuclear Physics and Nuclear Engineering, Faculty of Physics and Engineering Physics, VNUHCM- University of Science, 227 Nguyen Van Cu Street, District 5, Ho Chi Minh City, Vietnam 123 Journal of Radioanalytical and Nuclear Chemistry https://doi.org/10.1007/s10967-018-5858-5