Haque M.
Department of Electrical and Electronic Engineering, Southeast University, Permanent Campus, 251/A & 252. Tejgaon Industrial Area, Dhaka-1208, Bangladesh
Ferdous M. J
Health Physics Division, Atomic Energy Centre. Dhaka, Bangladesh.
Radioactivity concentrations, Soil parameters, Transfer factors.
Savar, Dhaka, Bangladesh
Risk Management in Agriculture
2.1. Location Bangladesh is located at 23.6850° N, 90.3563° E. It is lower lying than India and so it is highly possible that Bangladesh is suffering from radioactivity due to the situation of the source of the rivers in India (Chabaux et al. 2001). There are also some rivers that are situated in Nepal, Bhutan and flow through India. Therefore its land might be contaminated by radioactive sources from upstream. In this present research, the soil samples are collected from one of the most significant regions Savar in Bangladesh. It is located at the latitude and longitude coordinates of 23°58' N and 90°20' E. The water from coal mines runs off into agricultural fields and rivers. This coal mixed water is used for various purposes in these regions. Coal is a major source of radioactive materials released to the environment and coal combustion is more hazardous to health. Coal is mixed with the oxides of silicon, aluminum, iron, calcium, magnesium, titanium, sodium, potassium, arsenic, mercury, and sulfur plus small quantities of uranium and thorium. As there are radioactive elements of uranium and thorium groups mixed in coal, so coal can become a concern. Naturally occurring radionuclides such as 238U, 232Th and 40K and their progeny present in soil causes radiation exposure for the population. The activity concentrations of these nuclides are measured in many countries of the world including Bangladesh in order to monitor radiation level in the environment. Several studies have been carried out to determine the activity of naturally occurring radionuclides in the soil samples throughout Bangladesh and to derive the radiation hazard parameters to establish the radiation background database. There has not been much study of the northern part of Bangladesh. Along with natural radionuclides, we planned to detect 226Ra, 228Ra and 40K in the soil samples near the Savar Research Reactor regions. There are many principles, methods and techniques used to determine the amount of radioactivity in the environment. One of the widely used techniques is gamma-ray spectrometry (Ebaid 2010) which is common to all low-level radioanalysis and can be applicable to other environment contaminants. We planned to carry out the measurements using high resolution γ-ray spectroscopy with an HPGe detector in a low background configuration in Health Physics Division, Atomic Energy Centre (AEC), Dhaka. 2.2. Sample collection Sampling site was selected in the Northwestern part of Dhaka for the collection of plants (vegetables) and soil samples. Figure 1 shows the sampling sites of Savar (latitude 23°58' N and longitude 90°20' E). Plant and soil samples were collected in February 2016 from location in the selected sites of North-western part of Dhaka, Savar nuclear research reactor. The geographical representations of the locations are shown in Figure 1. All the locations selected for plant and soil sample collection were on agriculture land. Plants commonly grown and consumed were collected in the harvesting season. To ensure sufficient representation, ten plants from the different sampling sites near Savar Research Reactor were collected. Crops from Savar included pointed gourd (Trichosanthes dioica; P1), carrot (Daucus carota; P2), papaya (Carica papaya; P3 ), green banana (Musa acuminata; P4), radish (Raphanus sativus; P5), brinjal (Solanum melongena; P6 ), bitter gourd (Momordica charantia; P7), cauliflower (Brassica oleracea var botrytis; P8 ), potato (Solanum tuberosum, P9 ) and okra (Abelmoschus esculentus, P10). About 5-7 kg (on fresh weight basis) of edible parts of the plants was collected. Approximately 1 kg of soil surronding the roots of corresponding plants was collected at a depth of 0 to 15 cm from each sampling site in Savar. All soil samples were carefully collected by using a shovel. The collected soil samples depict the major soil category of the area. The samples were packed in dried acetonecleaned polyethylene bags. The bags were then labeled with sample codes and sealed. The labels included soil sample ID and location. Finally, the samples were transferred to the radiation detection laboratories of the Health Physics division, Atomic Energy Centre (AEC), Bangladesh. 2.3. Sample preparation Plant samples were cut into small pieces and primarily dried in air by spreading on separate sheets of brown paper. The samples were then dried in an electric oven at 70 ºC until friable. Then the samples were ground to powder by a grinder. Each of the collected soil samples were air dried by spreading on separate sheets of paper after it was transported to the laboratory. After air drying, the larger aggregates were broken by gentle crushing with a hammer. The soil samples were then dried in an electric oven at 105ºC and sieved through a 2 mm sieve. The properties of soil were determined by standard methods as used by BAEC, Dhaka (Gaffar et al. 2014). The soil samples contained sand, silt and clay. The pH (H2O) values ranged from 5.0-8.0. Organic matter (%) of the soil samples ranged from 1-2.5. Each of the plant and soil samples was transferred to cylindrical plastic containers of approximately equal size and shape. In order to maximize counting efficiency and precision and to minimize self-absorption for that specific geometry, containers of identical size and shape were used. The containers were then sealed tightly, wrapped with thick vinyl tapes around their screw necks, and stored for at least four weeks to reach equilibrium between the 238U (226Ra) and 232Th (228Ra) their respective progenies prior to measurement (Kabir et al. 2009).
SJSS. SPANISH JOURNAL OF SOIL SCIENCE YEAR 2017 VOLUME 7 ISSUE 2
Journal