Groundwater dissolves radioactive minerals like uranium, radium, radon and polonium during its flow. 226Ra, 222Rn, and 210Po are the decay products of the 238U series which causes ingestion dose to human being. The activity of these radionuclides was studied in groundwater samples collected from Chamarajanagar district, Karnataka, India. 226Ra, 222Rn and 210Po concentration in bore well water samples were varied from 2.18 to 96.42mBql− 1, 0.94 to 26.95Bql− 1, 0.72 to 6.33mBql− 1 respectively. The average ingestion dose due to 226Ra, 222Rn and 210Po were 6.41, 11.60 and 2.51µSvy− 1 respectively.
Research Article
Study of radiation dose due to 226Ra, 222Rn and 210Po in drinking water of Chamarajanagar district, Karnataka, India
https://doi.org/10.21203/rs.3.rs-3249682/v1
This work is licensed under a CC BY 4.0 License
Journal Publication
published 13 Jan, 2024
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Radon
Emanometry
Scintillation detector
Radionuclide
Ingestion Dose
Radiation is omnipresent and all living beings are continuously exposed to it. Radiation dose due to naturally occurring radionuclide is higher than those provided by manmade radiation sources (WHO 2017). Uranium is virtually found in all types of rocks and soils, when water passes through and over rocks and soil formations, it dissolves uranium and its daughter products and a trace amount of these radionuclides are found in ground and surface water.
226Ra, 222Rn and 210Po which are the daughter products of the 238U radioactive decay series have got importance because of their radiological effects when health issues are concerned. 226Ra is known to be one of the most toxic long-lived radioactive elements in environmental matrix (Sill 1987). 226Ra isotope has a longer half-life, is chemically similar to calcium, and about 80% of 226Ra tends to accumulate in the bones, thus increasing the internal radiation dose to the individuals (UNSCEAR 1982).
222Rn, an alpha emitting radioactive noble gas with a half-life of 3.82 days is the major contributor to radiation exposure among all natural radiation sources. 222Rn in water, when used in household activities, is released to the dwellings and mixed with the indoor air, which increases the inhalation dose apart from the ingestion dose. Studies have shown that inhalation of 222Rn dissolved in water has more impact on health hazards than the intake of water with certain content (UNSCEAR 2000). 222Rn decays into 218Po and 214Pb by emitting alpha particles, which when entered the human body damages the living cells, causing serious health hazards. In 1988, 222Rn has been classified as a human carcinogen by world health organization and it is the key cause for lung cancer in non-smokers and the second cause in smokers (WHO 2009).
210Po is another important natural radionuclide in the uranium decay series that causes internal dose. The half-life of 210Po is 138.4 days which undergo alpha decay (5.3 MeV) to produce 206Pb and delivers a significantly higher dose through ingestion. Therefore, 210Po is classified as a Group 1 human carcinogen (IARC 2001). 210Po is found in variable amounts in all types of natural water samples and has a high specific activity compared to that of 226Ra and 238U. About 7% of the natural internal radiation dose is due to ingestion of 210Po and about 18% of the internal dose to the people is due to ingestion of 210Po along with its precursor 210Pb [Bulman et al. 1995; Clayton and Bradley 1995). When ingested 210Po is mainly absorbed into blood compared to other alpha-emitting radionuclides like 239Pu (ICRP 1979, ICRP 1993). If 210Po enters blood, it is predominantly deposited in soft tissues and the most susceptible organs are liver, spleen, bone marrow, kidneys and skin (Leggett and Eckerman 2001). 210Po is not filtered by the kidneys as it strongly binds to haemoglobin and plasma proteins, hence renal excretion of 210Po is very slow compared to other radioactive elements (Thomas et al. 2001).
The estimation of radionuclides in drinking water and assessment of radiation dose to the population is important particularly when groundwater is used for household activities. Bore wells are the only sources of drinking water in major parts of the study area; therefore, it is very essential to estimate the activity of radionuclides in groundwater to assess the radiation dose to the population of the Chamarajanagar district of Karnataka, India. In the present investigation, the distribution of activity of these radionuclides in groundwater sources of the Chamarajanagar district was carried out. Ingestion and inhalation dose to the residents was also estimated. This type of extensive and systematic work has not been carried out in this region of study.
Study area
Chamarajanagar district lies between the latitudes 11º 40' 58"N and 12º 6' 32"N and longitudes 76º 24' 14"E and 77º 64' 55"E in the southern part of Karnataka, India. The geographical area is about 5,000 km2 and has an average altitude of 662 m above sea level. The topography is mountainous with north-south trending hill ranges of Indian Eastern Ghats.
The district has five taluks viz. Chamarajanagar, Gundlupet, Hanur, Kollegal and Yelandur (Fig. 1). This district is endowed with rich mineral resources including both metallic and non-metallic minerals. The major mineral available is black granite. Gneiss rocks are found in eastern parts and granite rocks are found in most parts of Kollegal taluk. The southern part of this taluk is surrounded by M.M. Hills. The B. R. Hills in Yelandur taluk is mainly surrounded by gneiss rock. Granite compositions like granodiorite and tonalite rock types are found in Gundlupet and Hanur taluks (CGWB 2008). Boreholes are the major sources of water supply for domestic and other purposes in the entire district. Groundwater which originates from granitic rocks that leach and dissolve radioisotopes may result in higher doses to the local population. The concentration of radionuclides on earth varies from region to region which mainly depends on the type of soil and rocks in the study area. Monazite and granite rocks are contain higher levels of radionuclides. Therefore, the distribution of radioactive elements in the groundwater and its relation with geological features of the area is studied in the present investigation.
222 Rn concentration in water samples
Water samples of about 500ml were collected in airtight vials from different sampling stations throughout the district. The representative sample was collected after flushing out the stagnant water in the bore well for about 30 minutes. To minimise 222Rn leakage and bubble formation during sample collection, the vials were completely filled by immersing them in the sample-filled container and closing the lids beneath the water. GPS of the location and sampling time were noted and the samples were bought to the laboratory at the earliest.
The activity of 222Rn in water samples was measured using the Smart Radon Monitor (SRM) (Figs. 2 and 3) (Gaware et al. 2011). The samples were analysed by incorporating the procedure of the American standard test method for 222Rn in drinking water (ASTM 1998). About 60 ml of sample was taken in the sampling holder. By bubbling air through the water, the dissolved 222Rn in the water was transferred to the scintillation cell through a progeny filter for the elimination of 222Rn /220Rn progeny. The scintillation cell, which is coupled to a photomultiplier tube and counting electronics will count the 222Rn and its decay products which have undergone radioactive decay by emitting alpha particles. Background counts due to the residual decay product of 222Rn will be eliminated using the indigenous smart algorithm of the microprocessor. The efficiency of the ZnS(Ag) scintillation cell used in the radon monitor is 74%
. Figure 2 Schematic representation of SRM Fig. 3 Radon measurements in water samples
The concentration of 222Rn in water samples is calculated using Eq. (1) (Raghavayya et al. 1980).
Where, CRn is the activity of 222Rn in the water sample (Bql− 1), D is the alpha counts (s− 1), B is the background counts (s− 1), V is the volume of the actual water sample taken for analysis (ml), E is the efficiency of the smart radon monitor, λ is the radioactive decay constant of 222Rn (2.09×10− 6 s− 1), t is the total time duration of counting (s) and T is the time delay after sample collection (s).
Dose Estimation
The effective dose due to inhalation and ingestion from 222Rn in water per annum is calculated by UNSCEAR established parameters. The inhalation and ingestion dose due to 222Rn in water are given by Eqs. (2) and (3) respectively (UNSCEAR 2000). The weighted average water consumption by the population of the district is considered to be 730ly− 1, recommended by WHO, to estimate the ingestion dose (WHO 2017).
Inhalation dose due to Rn in water
Where, Dinh is the annual effective inhalation dose (µSvy− 1), CRn is the activity concentration of 222Rn in the water sample (Bqll), Raw is the ratio between the concentration of 222Rn in the air to the concentration of 222Rn in water (10− 4), I is the average time spent by an individual in indoor (7000hy− 1), F is the equilibrium factor between 222Rn and its progeny (0.4) and FD is the dose conversion factor for 222Rn exposure (9 nSv (Bqhm− 3)−1).
Ingestion dose due to Rn in water through drinking pathway
Where, Ding is the effective ingestion dose (µSvy− 1), W is the weighted average water consumption (730 ly− 1) and EDC is the dose coefficient for 222Rn in water through ingestion (3.5 nSvBq− 1).
Estimation of Ra by emanometry method
Emanometry technique (Raghavayya et al. 1980) was employed to measure 226Ra concentration in water. For radium measurements in water, the locations were marked based on the results of radon measurements. From each taluk of Chamarajanagar district, 5–6 locations were identified and water samples of about 20 litres were collected in pre-cleaned cans. The pH of samples and GPS of the locations were also noted.
The water sample was filtered and pre-concentrated by co-precipitation and evaporation for 226Ra analysis. 5 g of analytical grade manganese dioxide was added and stirred for an hour using a mechanical stirrer and kept for two hours to settle down. The precipitated solution was separated for further analysis by discarding about half of the upper layer (supernatant) solution. The precipitate was heated to evaporate the water content and treated with 50 ml of concentrated hydrochloric acid. This solution was evaporated to near dryness and treated with 30ml of concentrated nitric acid to convert it into nitric acid medium and heated to near dryness to evaporate organic materials. The solution was allowed to cool and then treated with 50 ml of 4N HNO3 and filtered using Whatman 42 filter paper.
About 70ml of pre-concentrated solution was transferred to the radon bubbler (Fig. 4). Using a vacuum pump, the air was sucked through the solution to purge dissolved 222Rn. The solution-filled bubbler was kept undisturbed for 21 days (3–5 half-lives of 222Rn) for 222Rn build up (Figs. 4 and 5). An evacuated and background counted scintillation cell was connected to the bubbler through a swage connector. Air with dissolved 222Rn gets sucked through the solution and fills the scintillation cell under the influence of vacuum of the scintillation cell. The bubbling was made uniform and steady to have the complete transfer of 222Rn.The cell was kept for about 3–4 hours to have equilibrium between 222Rn and its daughter products. The alpha activity in the scintillation cell was measured using a scintillation-based programmable alpha counting system for duration of 1000 s. The activity of 226Ra in the water sample was calculated using Eq. (4) (Raghavayya et al. 1980).
Where, CRa is the activity of 226Ra in the water sample (mBql− 1), D is the alpha counts (s− 1), B is the background alpha counts (s− 1), V is the volume of the water sample taken for processing (about 20 l), E is the efficiency of the programmable alpha counting system (74%), λ is the radioactive decay constant of 222Rn (2.098 x 10− 6 s− 1), T is the time delay after transferring the solution from radon bubbler to the scintillation cell (s), t is the time duration of alpha counting (s) and τ is radon build-up period in the bubbler (s).
Ingestion dose due to 226Ra through drinking water pathway
Ingestion dose to the public due to the dissolved 226Ra in drinking water was estimated using the method and dose coefficients described in the IAEA reports (IAEA 2011). The ingestion dose per annum is calculated using Eq. (5) (UNSCEAR 2000).
Where, DRa is the ingestion dose due to 226Ra in water (µSvy− 1), W is the weighted average water consumption by the population (730ly− 1) and DCRa is the dose conversion factor for dissolved 226Ra in drinking water (2.8×10− 7 SvBq− 1).
Polonium in water
Sampling
Water samples of about 20 litres, collected from different regions of Chamarajanagar district were analysed for the 210Po activity by radiochemical analysis technique. Water samples were collected in clean plastic cans and the pH of the water was measured at each location.
Filtered water is transferred to a clean tub and hydrochloric acid is added to maintain the pH of the water to 2.0. Iron carriers (5g) were added to the solution and stirred for an hour using a specially designed mechanical stirrer. Ammonia solution is slowly added until the pH of the solution increase to 9.0 to precipitate iron as iron(III) hydroxide in the solution. The solution was stirred steadily for 6 hours and left undisturbed overnight for settling. The upper layer of this solution is discarded, and the precipitate is dissolved using conc. Hydrogen peroxide is added to remove the organic content present in the solution. Hydrochloric acid is added to this solution, stirred using a magnetic stirrer, and evaporated to near dryness in the beaker. The total dryness was avoided to prevent loss of 210Po due to volatilization and sorption onto the surface of the glass beaker. The residue is treated with 0.5M hydrochloric acid and to this solution ascorbic acid is added to avoid interference of ferric ion deposition on the silver disc (Sharma et al. 2021; WHO 2011).
Sample Processing
A background counted silver disc is immersed into the solution and stirred for 6 hours by maintaining the temperature at 90°C (Fig. 6). This process spontaneously deposits 99% of 210Po on the polished silver disc. After agitating for 6 hours, the silver disc is rinsed with double distilled water and ethanol and then dried. The silver disc is subjected to alpha counting and counts were recorded for 6000s on both surfaces (Kavitha et al. 2017; Makmur et al. 2020). The activity concentration of 210Po is calculated using Eq. (6).
Where, CPo is the activity of 210Po (mBql− 1), S is the background subtracted sample counts (s− 1), 𝜀 is the efficiency of alpha counting system (17.65%), Ep is the efficiency of 210Po deposition on a silver planchet (99%) and V is the volume of the water taken for processing (litre).
Ingestion dose due to 210Po in water through drinking pathway
The effective dose due to activity of 210Po in the ingested water per annum was calculated using Eq. (7) (Ahmed et al. 2018).
Where, DPo is the ingestion dose due to 210Po in water (µSvy− 1), W is the weighted average of water consumption (730 ly− 1) and DCPo is the dose conversion factor for 210Po (1.2×10− 6 SvBq− 1) (WHO 2017; ICRP 1996).
The activity of 222Rn in groundwater samples and the annual effective dose due to inhalation and ingestion of 222Rn are shown in Table 1. The samples were collected at 66 locations in Chamarajanagar district during 2020–2022 covering all the seasons of the year and the average value is presented in the Table 1 for each location. 222Rn concentration at different locations of the study area was found to vary from 0.94 to 26.95Bql− 1 with an average of 4.54Bql− 1. At all the locations the average values of 222Rn concentration were found to be below the suggested limits of 100Bql− 1 by WHO (2011). Relatively higher concentrations of 222Rn in water were observed at Manchahalli village of Gundlupet Taluk and Karinanjanapura village of Chamarajanagar taluk. 222Rn concentration in water samples is due to the presence of radium isotopes in surrounding rocks and soils. Granodiorite, tonalite and migmatic gneiss types of rocks are found in this region. During weathering of rocks, 226Ra will be transported from rocks and collected in the soil. During the transport of groundwater through rocks and soil 226Ra gets dissolved in groundwater. The annual inhalation dose varies from 2.37 to 67.91µSvy− 1 with an average of 11.44µSvy− 1 and annual ingestion dose varies from 2.40 to 68.86µSvy− 1 with an average of 11.60µSvy− 1. The total annual effective dose due to inhalation and ingestion varies from 4.77 to 136.77µSvy− 1 with an average of 23.04µSvy− 1. The total effective dose lies below the recommended limit of 1mSvy− 1 by WHO (2011).
The concentration of 226Ra and 210Po in bore well water samples and ingestion dose due to these radionuclides is shown in Table 2. The 226Ra concentration in water samples varies from 2.18 to 96.42mBql-1 with an average of 32.78mBql-1. Higher concentrations were observed at Beguru and Terakanambi villages of Gundlupet taluk due to granite rocks in the region which may contain higher concentrations of uranium. Also the depths of bore wells are more than 150m below the ground level and effluents from industries in these regions may also be the cause of increased radioactive elements in ground water. The lower concentrations are observed at villages of Yelandur taluk as this taluk is rich in surface water sources and the depth of bore wells are about 50 to 100 m below ground level. US-EPA has set the maximum contamination limit of 5 pCil-1 (0.185 Bql-1) for 226Ra in public water supplies (USEPA 2000), WHO has recommended 1Bql-1 for 226Ra as a safe limit in drinking water (WHO 2017). The ingestion dose due to 226Ra in water varied from 0.45 to 19.71µSvy-1 with an average of 6.41µSvy-1. These values are below the safe limits of 0.1mSvy-1 recommended by WHO (2011).
The concentrations of 210Po in ground water ranged between 0.72 to 6.33mBql-1 and its average value is found to be 2.86mBql-1. Higher concentration is observed at regions of Gundlupet taluk and regions of Hanur taluk showed lower concentrations. The higher concentration of 210Po is attributed to higher concentration of radionuclide in the phosphatic rocks. The European Union and World Health Organization recommend 100 mBql-1 as safe limit for 210Po in drinking water (WHO 2011). 210Po activity concentration in Chamarajanagar district is within safe limits. The ingestion dose varies from 0.63 to 5.55µSvy-1 with an average value of 2.51µSvy-1. These values are below the recommended value of 0.01mSvy-1 by WHO (1993) and 1 mSvy-1 by ICRP (2008).
The results are useful in identifying the relationship between 210Po and 226Ra concentrations in water samples. Figure 7 shows a scatter plot of 210Po concentration with 226Ra concentration. Due to the fact that 210Po is a decay product of 226Ra, a good correlation was observed between these two radionuclide with a Pearson’s r coefficient of 0.86. This finding will also indicate that 210Po and 226Ra might be of same origin.
The concentrations of the 226Ra, 222Rn and 210Po in groundwater samples varied from 2.18 to 96.42mBql− 1, 0.94 to 26.95Bql− 1 and 0.72 to 6.33mBql− 1 respectively. The average ingestion dose due to 226Ra, 222Rn and 210Po were 6.41, 9.74 and 2.51µSvy− 1 respectively. The total effective radiation dose due to ingestion of 226Ra and 210Po in water varied from 1.63 to 25.25µSvy− 1 with an average of 8.92µSvy− 1. The total radiation dose due to 222Rn in water through ingestion and inhalation varies from 4.77 to 136.77µSvy− 1 with an average of 23.04µSvy− 1. The present investigation shows that people of the study area are less prone to radiological hazards due to natural radionuclide in water. A good correlation between 226Ra and 210Po radionuclide is observed with a Pearson’s r coefficient of 0.86 indicating that they might be of the same origin.
1. Funding: Not applicable.
2. Informed Consent Statement: Not applicable.
3. Conflicts of Interest: The author declares no conflict of interest.
4. Ethical Approval Statement: Not applicable
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|
Sl. No |
Location |
Number of samples |
222Rn Conc. (Bql-1) |
Inhalation Dose (µSvy-1) |
Ingestion Dose (µSvy-1) |
Total Dose (µSvy− 1) |
|---|---|---|---|---|---|---|
|
Chamarajanagar Taluk |
||||||
|
1 |
Bendaravadi |
4 |
3.01 |
7.59 |
7.69 |
15.28 |
|
2 |
Bevinathalapura |
7 |
2.76 |
6.96 |
7.05 |
14.01 |
|
3 |
Chamarajanagar |
5 |
3.76 |
9.48 |
9.61 |
19.08 |
|
4 |
Chandakavadi |
4 |
1.42 |
3.58 |
3.63 |
7.21 |
|
5 |
Heggotara |
12 |
6.06 |
15.27 |
15.48 |
30.75 |
|
6 |
Hondarabalu |
3 |
2.17 |
5.47 |
5.54 |
11.01 |
|
7 |
Jyothigowdanapura |
3 |
3.29 |
8.29 |
8.41 |
16.70 |
|
8 |
Kagalavadi |
3 |
1.14 |
2.87 |
2.91 |
5.79 |
|
9 |
Karinanjanapura |
6 |
19.15 |
48.26 |
48.93 |
97.19 |
|
10 |
Kodimole |
3 |
2.03 |
5.12 |
5.19 |
10.30 |
|
11 |
Mariyala |
4 |
1.68 |
4.23 |
4.29 |
8.53 |
|
12 |
Muttige |
3 |
1.47 |
3.70 |
3.76 |
7.46 |
|
13 |
Nagavalli |
9 |
2.41 |
6.07 |
6.16 |
12.23 |
|
14 |
Nalluru |
6 |
2.62 |
6.60 |
6.69 |
13.30 |
|
15 |
Panyadahundi |
6 |
1.89 |
4.76 |
4.83 |
9.59 |
|
16 |
Ramasamudra |
3 |
12 |
30.24 |
30.66 |
60.90 |
|
17 |
Singanapura |
9 |
1.34 |
3.38 |
3.42 |
6.80 |
|
18 |
Umatturu |
6 |
1.22 |
3.07 |
3.12 |
6.19 |
|
Gundlupet Taluk |
||||||
|
1 |
Begur |
9 |
11.65 |
29.36 |
29.77 |
59.12 |
|
2 |
Chikkathuppur |
6 |
7.01 |
17.67 |
17.91 |
35.58 |
|
3 |
Gundlupet |
3 |
5.96 |
15.02 |
15.23 |
30.25 |
|
4 |
Guruvinapura |
7 |
4.94 |
12.45 |
12.62 |
25.07 |
|
5 |
Hammirhosahalli |
6 |
7.08 |
17.84 |
18.09 |
35.93 |
|
6 |
Hangala |
4 |
8.54 |
21.52 |
21.82 |
43.34 |
|
7 |
Hosapura |
6 |
4.52 |
11.39 |
11.55 |
22.94 |
|
8 |
Hunasinapura |
12 |
1.35 |
3.40 |
3.45 |
6.85 |
|
9 |
Kabbahalli |
9 |
8.4 |
21.17 |
21.46 |
42.63 |
|
10 |
Kottalavadi |
9 |
9.03 |
22.76 |
23.07 |
45.83 |
|
11 |
Kutluru |
4 |
7.96 |
20.06 |
20.34 |
40.40 |
|
12 |
Madapattana |
6 |
15.82 |
39.87 |
40.42 |
80.29 |
|
13 |
Manchahalli |
4 |
26.95 |
67.91 |
68.86 |
136.77 |
|
14 |
Mukha halli |
6 |
7.7 |
19.40 |
19.67 |
39.08 |
|
15 |
Shindanapura |
5 |
8.07 |
20.34 |
20.62 |
40.96 |
|
16 |
Shyanadrahalli |
9 |
6.44 |
16.23 |
16.45 |
32.68 |
|
17 |
Somahalli |
6 |
7.72 |
19.45 |
19.72 |
39.18 |
|
18 |
Terakanambi |
6 |
10.07 |
25.38 |
25.73 |
51.11 |
|
Kollegal Taluk |
||||||
|---|---|---|---|---|---|---|
|
1 |
Chikkinduvadi |
6 |
1.68 |
4.23 |
4.29 |
8.53 |
|
2 |
Haravanapura |
6 |
1.9 |
4.79 |
4.85 |
9.64 |
|
3 |
Jinakanahalli |
8 |
1.34 |
3.38 |
3.42 |
6.80 |
|
4 |
Kollegal |
10 |
1.64 |
4.13 |
4.19 |
8.32 |
|
5 |
Kunthur |
6 |
1.1 |
2.77 |
2.81 |
5.58 |
|
6 |
Madhuvanahalli |
8 |
1.62 |
4.08 |
4.14 |
8.22 |
|
7 |
Palya |
6 |
2.76 |
6.96 |
7.05 |
14.01 |
|
8 |
Siddaiahnapura |
8 |
1.68 |
4.23 |
4.29 |
8.53 |
|
9 |
Singanallur |
6 |
2.41 |
6.07 |
6.16 |
12.23 |
|
10 |
Teramballi |
10 |
3.75 |
9.45 |
9.58 |
19.03 |
|
Yelandur Taluk |
||||||
|
1 |
Alkere agrahara |
9 |
1.38 |
3.48 |
3.53 |
7.00 |
|
2 |
Ambale |
6 |
2.14 |
5.39 |
5.47 |
10.86 |
|
3 |
Gumballi |
8 |
2.6 |
6.55 |
6.64 |
13.20 |
|
4 |
Honnuru |
9 |
5.14 |
12.95 |
13.13 |
26.09 |
|
5 |
Kesturu |
8 |
1.62 |
4.08 |
4.14 |
8.22 |
|
6 |
Maddur |
9 |
1.38 |
3.48 |
3.53 |
7.00 |
|
7 |
Vadagere |
6 |
1.1 |
2.77 |
2.81 |
5.58 |
|
8 |
Yelandur |
6 |
2.8 |
7.06 |
7.15 |
14.21 |
|
9 |
Yeragamballi |
12 |
1.78 |
4.49 |
4.55 |
9.03 |
|
10 |
Yeriyuru |
9 |
2.02 |
5.09 |
5.16 |
10.25 |
|
Hanur Taluk |
||||||
|
1 |
Bandalli |
3 |
0.94 |
2.37 |
2.40 |
4.77 |
|
2 |
Bataguppa |
11 |
1.2 |
3.02 |
3.07 |
6.09 |
|
3 |
Cowdalli |
6 |
5.43 |
13.68 |
13.87 |
27.56 |
|
4 |
Hanur |
10 |
1.42 |
3.58 |
3.63 |
7.21 |
|
5 |
Mahadeshwarabetta |
6 |
1.99 |
5.01 |
5.08 |
10.10 |
|
6 |
Managalli |
3 |
4.07 |
10.26 |
10.40 |
20.66 |
|
7 |
Mangala |
9 |
3.76 |
9.48 |
9.61 |
19.08 |
|
8 |
Martalli |
4 |
2.39 |
6.02 |
6.11 |
12.13 |
|
9 |
Nagamale |
9 |
2.38 |
6.00 |
6.08 |
12.08 |
|
10 |
Talabetta |
9 |
5.58 |
14.06 |
14.26 |
28.32 |
|
Minimum |
0.94 |
2.37 |
2.40 |
4.77 |
||
|
Maximum |
26.95 |
67.91 |
68.86 |
136.77 |
||
|
Average |
4.54 |
11.44 |
11.60 |
23.04 |
||
Table 2 226Ra and 210Po concentration in bore well water samples and ingestion dose
|
Sl. No |
Sampling area |
Latitude Longitude |
Concentration mBql− 1 |
Ingestion dose µSvy− 1 |
|||
|---|---|---|---|---|---|---|---|
|
226Ra |
210Po |
226Ra |
210Po |
Total |
|||
|
1 |
Ramasamudra |
11.933273°N, 76.963046°E |
15.93 |
2.87 |
3.26 |
2.51 |
5.77 |
|
2 |
Panyadahundi |
11.994062°N, 76.858236°E |
12.98 |
1.18 |
2.65 |
1.03 |
3.69 |
|
3 |
Bevinathalapura |
11.494367°N, 76582258°E |
19.49 |
3.89 |
3.98 |
3.41 |
7.39 |
|
4 |
Gundlupet |
11.804419°N, 76.674734°E |
68.91 |
4.10 |
14.09 |
3.59 |
17.68 |
|
5 |
Terakanambi |
11.814017°N, 76.777815°E |
93.83 |
5.21 |
19.18 |
4.56 |
23.74 |
|
6 |
Beguru |
11.906498°N, 76.672617°E |
96.42 |
6.33 |
19.71 |
5.55 |
25.25 |
|
7 |
Hanur |
12.096822°N, 77.332927°E |
10.63 |
1.46 |
2.17 |
1.28 |
3.45 |
|
8 |
Bataguppe |
12.107349°N, 77.310886°E |
6.07 |
0.72 |
1.24 |
0.63 |
1.87 |
|
9 |
Kollegal |
12.152088°N, 77.108920°E |
7.14 |
1.36 |
1.46 |
1.19 |
2.65 |
|
10 |
Teramballi |
12.138295°N, 77.059710°E |
16.59 |
3.89 |
3.39 |
3.41 |
6.80 |
|
11 |
Yelandur |
12.058514°N, 77.031679°E |
2.18 |
1.35 |
0.45 |
1.18 |
1.63 |
|
12 |
Honnuru |
12.069980°N, 77.010633°E |
26.34 |
1.98 |
5.38 |
1.73 |
7.12 |
|
Minimum |
2.18 |
0.72 |
0.45 |
0.63 |
1.63 |
||
|
Maximum |
96.42 |
6.33 |
19.71 |
5.55 |
25.25 |
||
|
Average |
32.78 |
2.86 |
6.41 |
2.51 |
8.92 |
||
|
Geo. Mean |
18.12 |
2.34 |
3.66 |
2.05 |
6.02 |
||
No competing interests reported.