N.K. Sethy

Bioaccumulation of 226Ra by plants growing in fresh water ecosystem around the uranium industry at Jaduguda, India.

A field study has been conducted to evaluate the (226)Ra bioaccumulation among aquatic plants growing in the stream/river adjoining the uranium mining and ore-processing complex at Jaduguda, India. Two types of plant group have been investigated namely free floating algal species submerged into water and plants rooted in stream & riverbed. The highest (226)Ra activity concentration (9850 Bq kg(-1)) was found in filamentous algae growing in the residual water of tailings pond. The concentration ratios of (226)Ra in filamentous algae (activity concentration of (226)Ra in plant Bq kg(-1) fresh weight/activity concentration of (226)Ra in water Bq l(-1)) widely varied i.e. from 1.1 x 10(3) to 8.6 x 10(4). Other aquatic plants were also showing wide variability in the (226)Ra activity concentration. The ln-transformed filamentous algae (226)Ra activity concentration was significantly correlated with that of ln-transformed water concentration (r = 0.89, p < 0.001). There was no correlation between the activity concentrations of (226)Ra in stream/riverbed rooted plants and the substrate. For this group, correlation between (226)Ra activity concentration and Mn, Fe, Cu concentration in plants were statistically significant.

Natural radioactivity in roadside soil along Jamshedpur-Musabani road: a mineralised and mining region, Jharkhand and associated risk.

The specific activity and the gamma radiation dose rates due to naturally occurring radioactive materials ((238)U, (232)Th and (40)K) were determined in 26 roadside surface soils along Jamshedpur-Musabani road-a mineralised and mining region, using high-resolution gamma-ray spectrometry. The concentrations of (238)U, (232)Th and (40)K in the soil samples were found to be in the range of 16.6 +/- 0.6-390.5 +/- 1.6, 24.1 +/- 0.7-148.2 +/- 2.1 and 85.9 +/- 3.8-881.6 +/- 22.4 Bq kg(-1), respectively. The annual effective dose equivalent was found to be in the range of 0.04-0.32 mSv y(-1) with an average value of 0.13 mSv y(-1). The excess cancer risk is in the range of 0.16 x 10(-3)-1.22 x 10(-3) with an average value of 0.49 x 10(-3).

Study of the distribution of 226Ra in ground water near the uranium industry of Jharkhand, India

Ground water is the principal source of drinking water in the rural areas of India. With the aim of determining, the contribution of (226)Ra to natural background radiation through drinking water exposure pathway near an operating uranium mining industry at Jaduguda, Jharkhand state of eastern India, the (226)Ra activity concentrations were measured in potable ground water. The water analysed, both tube well and well water, was collected in areas near the uranium industry and away. The (226)Ra concentration was measured by emanometric technique. The (226)Ra level in ground water was ranging between minimum detection limit of 3.5 mBq l(-1) and a maximum of 208 mBq l(-1). The analysis of variance reveals that there is insignificant statistical variation in the median (226)Ra concentration up to a distance of >10 km from the mining complex. Variation in concentration of (226)Ra in sources is attributed to the local geochemistry and environmental factors. The (226)Ra concentration was significantly elevated in natural artesian wells in the vicinity of uranium mineralised hill and it varies from 53.4 to 754 mBq l(-1). The WHO [Guidelines for Drinking Water Quality. Third Edition, Vol. 1, Recommendation (2004)] guideline value of 1000 mBq l(-1) has not been exceeded in any of the sources investigated.

Uptake of uranium by aquatic plants growing in fresh water ecosystem around uranium mill tailings pond at Jaduguda, India.

Concentration of uranium was determined in aquatic plants and substrate (sediment or water) of fresh water ecosystem on and around uranium mill tailings pond at Jaduguda, India. Aquatic plant/substrate concentration ratios (CRs) of uranium were estimated for different sites on and around the uranium mill tailings disposal area. These sites include upstream and downstream side of surface water sources carrying the treated tailings effluent, a small pond inside tailings disposal area and residual water of this area. Three types of plant groups were investigated namely algae (filamentous and non-filamentous), other free floating & water submerged and sediment rooted plants. Wide variability in concentration ratio was observed for different groups of plants studied. The filamentous algae uranium concentration was significantly correlated with that of water (r=0.86, p<0.003). For sediment rooted plants significant correlation was found between uranium concentration in plant and the substrate (r=0.88, p<0.001). Both for other free floating species and sediment rooted plants, uranium concentration was significantly correlated with Mn, Fe, and Ni concentration of plants (p<0.01). Filamentous algae, Jussiaea and Pistia owing to their high bioproductivity, biomass, uranium accumulation and concentration ratio can be useful for prospecting phytoremediation of stream carrying treated or untreated uranium mill tailings effluent.

A review of radio chemical analysis and estimation of 210Po in soil matrices

Abstract The naturally occurring radionuclide 210Po, arising from the uranium–radium decay series, provides a considerable contribution to the radiation exposure to humans. Polonium is analyzed for a variety of purposes, including for radiological impact assessment or as a tracer of environmental processes. Losses of polonium may occur at temperatures above 100°C, depending on conditions, requiring particular care in sample preparation and treatment. There has been little development regarding analysis of polonium in environmental samples since 1960 as radiochemical analysis of polonium is quite straight forward due to easy of source preparation through auto-deposition on to metal surfaces. In this paper a brief review of estimation of polonium in the soil samples have given emphasis.

A simple method for calibration of Lucas scintillation cell counting system for measurement of 226Ra and 222Rn

Abstract Known quantity of radium from high grade ore solution was chemically separated and carefully kept inside the cavity of a Lucas Cell (LC). The 222Rn gradually builds up and attain secular equilibrium with its parent 226Ra. This gives a steady count after a suitable buildup period (>25 days). This secondary source was used to calibrate the radon counting system. The method is validated in by comparison with identical measurement with AlphaGuard Aquakit. The radon counting system was used to evaluate dissolved radon in ground water sample by gross alpha counting in LC. Radon counting system measures the collected radon after a delay of >180min by gross alpha counting. Simultaneous measurement also carried out by AlphaGuard Aquakit in identical condition. AlphaGuard measures dissolved radon from water sample by constant aeration in a closed circuit without giving any delay. Both the methods are matching with a correlation coefficient of >0.9. This validates the calibration of Lucas scintillation cell counting system by designed encapsulated source. This study provides an alternative for calibration in absence of costly Radon source available in the market.

Uptake of 210Po by aquatic plants of a fresh water ecosystem around the uranium mill tailings management facility of Jaduguda, India.

Abstract Purpose: The present study was designed to investigate the uptake of Polonium-210 (210Po) by aquatic plants growing in a fresh water ecosystem around the tailings management facility of the uranium industry of Jaduguda, India. Evaluation of the activity concentration of 210Po in aquatic plants, the concentration ratio of 210Po from substrate to plants and the relationship of 210Po with other stable elements were major objectives of the investigation. Materials and methods: Based on the habitat, three types of plant were collected and analyzed for 210Po activity estimation. Along with aquatic plants, effluent, surface water and bottom sediment were also collected and analyzed for 210Po activity content. From the acid solution 210Po was electrodeposited on brightly polished silver discs and counted for alpha activity in an alpha counter. Results: The highest 210Po activity concentration (4884 Bq kg−1 fresh weight) was found in filamentous algae from residual water of the tailings pond. For sediment-rooted plants, a significant positive correlation (r = 0.91, p < 0.0001) was observed between plant and sediment activity concentration of 210Po. Conclusions: For all of the three different groups of plants studied, highly significant correlations were observed between activity concentration of 210Po and Cu with the significance level variation between 0.00–0.05 (both for linear and log transformed data).

Comparison of natural distribution pattern of uranium in groundwater in the vicinity of tailings management facilities at Jaduguda and Turamdih in Singhbhum region, Jharkhand

The results of uranium analyses in groundwater samples collected from areas adjacent to Turamdih and Jaduguda sites of solid waste disposal facilities (tailings pond) of process waste of the uranium industry are presented in the paper. These villages are within a distance of 0.5 km from tailings pond at either site. The concentration of uranium in approximately one-third of the samples was below the minimum detection limit (MDL) of 0.5 mg/m 3 . The highest uranium concentration of 16 mg/m 3 was found in tube well sample at the base of uranium mineralized hill of Turamdih with a median concentration of 0.95 mg/m 3 . Around tailings management facility at Jaduguda, the median concentration was 1.1 mg/m 3 with a maximum concentration of 10.9 mg/m 3 . The variations in monitoring results reflect the nature of uranium mineralization at the two sites. The results around Turamdih tailings pond show a high degree of asymmetry. Barring the MDL values, the lognormal distribution of uranium in groundwater around Jaduguda tailings pond was observed. The results reflect the natural distribution of uranium around the facility and contribution of tailings pond was not found in groundwater sources adjoining these facilities.