This study assesses the 'radio-ecological' impacts of Fukushima nuclear accident on non-human biota using the ERICA Tool, which adopts an internationally verified methodology. The paper estimates the impacts of the accident on terrestrial and marine biota based on the environmental data reported in literature for Japan, China, South Korea and the USA. Discernible impacts have been detected in the marine biota around Fukushima Daiichi nuclear power plant. This study confirms that the Fukushima accident had caused heavier damage to marine bionts compared with terrestrial flora and fauna, in Japan.
A terrestrial gamma radiation survey for the state of Selangor, Kuala Lumpur and Putrajaya was conducted to obtain baseline data for environmental radiological health practices. Based on soil type, geological background and information from airborne survey maps, 95 survey points statistically representing the study area were determined. The measured doses varied according to geological background and soil types. They ranged from 17 nGy h(-1) to 500 nGy h(-1). The mean terrestrial gamma dose rate in air above the ground was 182 ± 81 nGy h(-1). This is two times higher than the average dose rate of terrestrial gamma radiation in Malaysia which is 92 nGy h(-1) (UNSCEAR 2000). An isodose map was produced to represent exposure rate from natural sources of terrestrial gamma radiation.
Measurements of the environmental terrestrial gamma radiation dose rate (TGRD) in each district of Kelantan state, Malaysia, were carried out using a portable hand-held radiation survey meter and global positioning system. The measurements were done based on geology and soil types of the area. The mean TGRD was found to be 209 nGy h(-1). Few areas of relatively enhanced activity were observed in Pasir Mas, Tanah Merah and Jeli districts, which have a mean TGRD between 300 and 500 nGy h(-1). An isodose map of the area was produced using ArcGIS software version 9.3.
This study was aimed at providing the baseline data of terrestrial gamma dose rates and natural radioactivity to assess the corresponding health risk in the ambient environment of the Pahang State. Terrestrial gamma radiation (TGR) from 640 locations was measured with the mean value found to be 176 ± 5 nGy h(-1). Ninety-eight soil samples were analysed using a high-purity germanium detector (HPGe), and the mean concentrations of the radionuclides (226)Ra, (232)Th and (40)K are 110 ± 3, 151 ± 5 and 542 ± 51 Bq kg(-1), respectively.(226)Ra and (232)Th concentrations were found to be three times the world average, while that of (40)K is quite higher than the world average value. The acid-intrusive geological formation has the highest mean concentrations for (226)Ra (215 ± 6 Bq kg(-1)), (232)Th (384 ± 12 Bq kg(-1)) and (40)K (1564 ± 153 Bq kg(-1)). The radium equivalent activities (Req) and the external hazard index (Hex) for the various soil types were also calculated. Some of the soil types were found to have values exceeding the internationally recommended levels of 370 Bq kg(-1) and the unity value, respectively.
Nasarawa State is located in north central Nigeria and it is known as Nigeria's home of solid minerals. It is endowed with barite, copper, zinc, tantalite and granite. Continuous releases of mining waste and tailings into the biosphere may result in a build-up of radionuclides in air, water and soil. This work therefore aims to measure the activity concentration levels of primordial radionuclides in the soil/sediment samples collected from selected mines of the mining areas of Nasarawa State. The paper also assesses the radiological and radio ecological impacts of mining activities on the residents of mining areas and their environment. The activity concentrations of primordial radionuclides ((226)Ra, (232)Th and (40)K) in the surface soils/sediment samples were determined using sodium iodide-thallium gamma spectroscopy. Seven major mines were considered with 21 samples taken from each of the mines for radiochemistry analysis. The human health hazard assessment was conducted using regulatory methodologies set by the United Nations Scientific Committee on the Effects of Atomic Radiation, while the radio ecological impact assessment was conducted using the ERICA tool v. 1.2. The result shows that the activity concentrations of (40)K in the water ways of the Akiri copper and the Azara barite mines are 60 and 67% higher than the world average value for (40)K, respectively. In all mines, the annual effective dose rates (mSv y(-1)) were less than unity, and a maximum annual gonadal dose of 0.58 mSv y(-1) is received at the Akiri copper mine, which is almost twice the world average value for gonadal dose. The external hazard indices for all the mines were less than unity. Our results also show that mollusc-gastropod, insect larvae, mollusc-bivalve and zooplankton are the freshwater biotas with the highest dose rates ranging from 5 to 7 µGy h(-1). These higher dose rates could be associated with zinc and copper mining at Abuni and Akiri, respectively. The most exposed terrestrial reference organisms are lichen and bryophytes. In all cases, the radio ecological risks are not likely to be discernible. This paper presents a pioneer data for ecological risk from ionizing contaminants due to mining activity in Nasarawa State, Nigeria. Its methodology could be adopted for future work on radioecology of mining.
The Keffi area hosts abundant pegmatite bodies as a result of the surrounding granitic intrusions. Keffi is part of areas that are geologically classified as North Central Basement Complex. Data on the mineralogy and mineralogical zonation of the Keffi pegmatite are scanty. Hence the need to understand the geology and mineralogical zonation of Keffi pegmatites especially at different depth profiles is relevant as a study of the elemental composition of the pegmatite is essential for the estimation of its economic viability. Here, the relative standardization method of instrumental neutron activation analysis (INAA) has been used to investigate the vertical deviations of the elemental concentrations of rare earth elements (REEs) at different depth profile of Keffi pegmatite. This study adopted the following metrics in investigating the vertical variations of REEs concentrations. Namely, the total contents of rare earth elements (∑REE); ratio of light to heavy rare earth elements (LREE/HREE), which defines the enrichment or depletion of REEs; europium anomaly (Eu/Sm); La/Lu ratio relative to chondritic meteorites. The study showed no significant variations in the total content of rare elements between the vertical depth profiles (100-250m). However, higher total concentrations of REEs (~ 92.65ppm) were recorded at the upper depth of the pegmatite and the europium anomaly was consistently negative at all the depth profiles suggesting that the Keffi pegmatite is enriched with light REEs.
Terrestrial gamma radiation dose (TGRD) rates were measured in situ from different locations in Katsina State, Nigeria, using a portable radiation survey metre based on geological formations and soil types. The measured TGRD rates ranged from 45 to 271 nGyh-1 with an average value of 116 ± 1 nGyh-1. Geological formation (silicified sheared rock) and soil type (lithosols and ferruginous crusts and ferruginous tropical soils) appeared to have the highest mean TGRD values of 163 and 134 nGyh-1 with sandstone geological formation and alluvial and hydromorphic soils having the lowest TGRD with values of 80 and 61 nGyh-1, respectively. One way ANOVA results shows that the tested null hypothesis was rejected. Thus, indicating that there exists a strong relationship between the various geological formations, soil types with the measured TGRD values based on the alternate hypothesis. Human health hazard indices like annual effective dose equivalent (AEDE), lifetime outdoor annual equivalent dose, and relative excess lifetime outdoor cancer risk associated with the mean TGRD of the study area were also calculated and found to be 0.711, 9.955 mSv, and 5.79 × 10-4, respectively. These values were higher than the world average values but favourable compared with the safety limits recommended by ICRP.