F1000ResearchF1000Research2046-1402F1000 Research LimitedLondon, UK10.12688/f1000research.162525.3Data NoteArticlesThe distribution of groundwater uranium in Chintamani village, Karnataka, India
[version 3; peer review: 1 approved, 2 approved with reservations]
RampurSadashivaInvestigationhttps://orcid.org/0009-0006-1064-80641V. K.Mahesh KumarInvestigation1PelliPavan R.Investigation1SarkarSenjutiConceptualizationInvestigationMethodology1PramanikSamayetaInvestigation1MajumderUpamaInvestigation1S.ShravanthiInvestigation1Meenakshi T.BhavanaInvestigation1G. SanthanakrishnanSrinidhiFormal Analysis1PendemRushiFormal Analysis1GhoshTanushreeConceptualizationMethodologySupervision1NagarajanDeepeshConceptualizationData CurationMethodologyProject AdministrationSupervisionVisualizationWriting – Original Draft PreparationWriting – Review & Editinghttps://orcid.org/0000-0001-8468-9834a1
Department of Biotechnology, Faculty of Life and Allied Health Sciences, M.S. Ramaiah University of Applied Sciences, Bengaluru, Karnataka, 560054, Indiadeepeshn.bt.ls@msruas.ac.in
Chintamani village, Chikkaballapura district, Karnataka, India was found to possess high aquifer uranium concentrations. Geologically, Chintamani village is located on bedrock that is rich in elements like potassium (K) that naturally contain high levels of radioactive elements, such as uranium and thorium, due to the presence of alkali-feldspar granites and gneisses. Aquifer depletion has caused the concentration of these elements in groundwater to increase over time, posing a potential health hazard to the residents of Chintamani village.
Methods
Here, we report the sampling of groundwater from 12 borewells located in Chintamani village in between the period of August 2024 to December 2024. We observed groundwater uranium concentrations of 0.018 ppm to 8.64 ppm. Data for borewell depth, the quantity of total dissolved solids (TDS), and the elemental composition of TDS is also reported. We observed a statistically significant spatial distribution of uranium concentrations in Chintamani village. Borewells possessing the highest observed concentrations of uranium were clustered towards the northwestern region of the village.
Conclusions
This dataset is expected to serve as a resource for guiding potential remediation efforts in these locations.
Uraniumheavy metalshydrogeologyaquifer contaminationThe author(s) declared that no grants were involved in supporting this work.Amendments from Version 2
This version addresses comments made by Reviewer 2 and Reviewer 3. Reviewer 2 requested a spatial map of uranium concentrations. This has been done and presented in Figure 1B. We used local kernel density estimate (KDE) smoothing to predict area-wide uranium concentrations. We have also discussed the implications of our findings and the need for further work in order to address the environmental and public health effect of groundwater uranium concentrations. As per the request of Reviewer 3, we have included a rationale for including elemental analysis in our study. We have also briefly discussed the correlation between uranium and nitrogen concentrations. We found no correlation between these variables, indicating that nitrate fertilizers may not play a role in mobilizing uranium from bedrock in this location.
Introduction
Uranium in groundwater primarily originates from natural geological sources, particularly from uranium-rich bedrock. Uranium may occur at high concentrations in intrusive igneous rocks, including two-mica granite, calc-alkaline granites, and alkalic plutonic rocks at concentrations of 3–300 ppm.
1 The crystal structures of igneous minerals like biotite, muscovite, K/Na-feldspar, and quartz may incorporate uranium in the percent range.
2,
3 Uranium is also found in sedimentary rocks such as shales (2-4 ppm), bauxite (11.4 ppm) and lignite (
<50-80 ppm).
1
Deep, water-stressed aquifers are frequently in contact with uranium-rich bedrock, enabling uranium to leach out into the surrounding groundwater. While this is a geogenic process, human activities can further exacerbate uranium contamination in groundwater. The use of nitrate-based fertilizers enhances the mobility of uranium by making it more soluble in water.
4 Additionally, over-extraction of groundwater lowers the water table, requiring deeper borewells to be drilled into uranium-rich bedrock. Diverse regions across the world experiencing water stress also display higher groundwater uranium content. Uranium concentrations in San Joaquin Valley, California, were observed to exceed federal and state drinking water standards of ≤30 ppb.
5 Groundwater in the Datong Basin, China, displayed uranium concentrations of
<0.02–288 ppb, with a mean of 24 ppb.
6 Likewise, high groundwater uranium concentrations have been reported in southern Finland, Germany, Portugal,
7 Japan, Mongolia, Uzbekistan and, India.
8
Uranium adversely affects crops grown on soil irrigated with contaminated groundwater. Uranium’s phytotoxic effects include inhibition of photosynthesis, inhibition of plant growth, protein and lipid membrane oxidation, overproduction of reactive oxygen species, and DNA breakage.
9 Uranium primarily accumulates in root systems, with negligible amounts found in aerial parts of plants
10 and is therefore a greater concern for root and tuber crops.
Dermal exposure results in minimal toxicity, particularly if Uranium is in an insoluble form.
11 Uranium in groundwater is typically present as sparingly soluble uranyl carbonate complexes,
12 minimizing the risk of absorption through the dermal route. Insteal, oral consumption of uranium through drinking untreated uranium-contaminated groundwater is of more concern. Although uranium is weakly radioactive, its primary health risk stems from its chemical toxicity rather than its radioactivity. Chronic exposure to uranium-contaminated water is associated with nephrotoxicity,
13,
14 with adverse renal effects reported in both laboratory animals and humans.
15 Uranium excretion in urine is correlated with phosphate and calcium excretion.
15 Other adverse effects include inhibition of bone function and development,
16 reproductive and developmental toxicity.
17
In this data note, we report data obtained from five randomly selected borewells in Chintamani village, Chikkaballapura District, Karnataka, India. Subsequently, seven additional borewells were selected in the vicinity of the borewell exhibiting the highest uranium concentration among the initial five. The site selection was based on accessibility and its proximity to our university. We report the uranyl concentrations (ICP-MS), and TDS elemental compositions (SEM-EDS) of groundwater obtained from all the wells sampled. A previous survey conducted by R. Srinivasan et al. fluorimetrically measured concentrations of groundwater uranium from 73 borewells spread across 13 districts of Eastern Karnataka,
18 reporting high uranium concentrations of
>1 ppm in Chitradurga, Tumkur, Kolar, and Chikkaballapura districts of southeastern Karnataka. The bedrock in these districts is composed primarily of Neoarchean granites, gneisses, and migmatites.
18 The borewells we sampled displayed uranium concentrations ranging from 0.018 ppm to 8.64 ppm, confirming the concentration ranges reported in the previous survey. Furthermore, most wells sampled possessed groundwater uranium concentrations exceeding the permissible limits established by WHO (30 ppb) and AERB (60 ppb) supported by ICP-MS data.
19 We have mapped the spatial distribution of groundwater within Chintamani village. We observed a significantly higher concentration of uranium was observed in borewells clustered at the northeastern region of Chintamani village, meriting further investigation of the village’s local geological features.
MethodsSample collection
Groundwater samples from Chintamani village were collected using the purge and sample method. Each borewell was pumped for five minutes to remove stagnant water from the well casing and tubing. After purging, a 2 L water sample was collected in a clean polypropylene bottle.
Table 1 lists the latitude, longitude, and date of collection for every sample.
Uranium concentrations (in ppm) for groundwater collected from Chintamani village.
Concentrations ≥ 0.03 ppm are underlined. Concentrations ≥ 0.06 ppm are in bold.
Borewell name
Collection date
Latitude
Longitude
U (ppm)
Borewell depth (feet)
TDS (mg
/L)
Borewell 1
28Aug2024
13.407162
78.042081
0.771
1250
789.60
Borewell 2
28Aug2024
13.391223
78.054693
0.018
1550
192.30
Borewell 3
28Aug2024
13.380344
78.033369
0.02
1600
183.40
Borewell 4
28Aug2024
13.393505
78.071632
0.143
350
1009.60
Borewell 5
28Aug2024
13.376384
78.07072
0.035
No data
548.00
Borewell 6
30Nov2024
13.409183
78.04178
0.595
No data
2099.50
Borewell 7
21Dec2024
13.4075572
78.0395479
4.15
1200
542.70
Borewell 8
21Dec2024
13.4082796
78.038472
8.64
2000
706.20
Borewell 9
21Dec2024
13.4093118
78.0357153
0.12
200
686.40
Borewell 10
21Dec2024
13.4088807
78.0417362
0.74
1500
844.50
Borewell 11
21Dec2024
13.4118821
78.0413087
1.27
150
638.50
Borewell 12
21Dec2024
13.4117252
78.0423317
0.21
200
891.10
Mean
1.39
1000.00
760.98
SD
2.55
702.38
490.99
Corr. coeff.
0.49
-0.05
P-value
0.15
0.88
Total dissolved solids (TDS) quantification
For every borewell sample, 1 L of water was dried in a hot-air oven at 80°C in a clean
Borosil®borosilicate 1L glass beaker until only the salt residue remained. This residue was weighed using a
Shimadzu AXT224R precision balance (least count = 0.1 mg) and subjected to SEM-EDS in order to determine its elemental composition.
Inductively coupled plasma mass spectrometry (ICP-MS)
ICP-MS experiments to quantify uranium concentration in the parts per million (ppm) range was performed by
Eurofins Scientific India using a
PerkinElmer®350X instrument. A 20-40 mL sample from each borewell was submitted. The sample was acidified with nitric acid to adjust the pH to ≤2. The instrument was set to detect elemental uranium concentrations. Raw data were interpreted using the
Syngistix™ software (version 4.0, PerkinElmer
®). Raw data may also be interpreted using
openMS. ICP-MS reports for each sample can be found in Supplementary Dataset S1.
20
Scanning electron microscopy - energy-dispersive X-ray spectroscopy (SEM-EDS)
An
FEI (Field Electron and Ion Company) Quanta 200 scanning electron microscope at Icon Labs Pvt. Ltd., Mumbai was used to perform SEM-EDS experiments. Samples were observed under a low vacuum mode at 20 kV, and with a chamber pressure of 65 Pascal. SEM-EDS has a least count of 0.1% (by weight) and cannot detect elements below this concentration. SEM-EDS spectra and reports quantifying the elemental composition of each sample can be found in Supplementary Dataset S2.
21
Data representation and statistical analyses
All statistical analyses were performed using the
R programming language (version 4.4.2). The
Leaflet package22 was used to generate a physical map of Chintamani village (
Figure 1). The Welch 2-sample T-test (one-tailed) was used to determine whether there existed a statistically significant difference between uranyl concentrations in different spatial locations in Chintamani village (
Figure 1). This was performed using the function t.test. Pearson’s correlation coefficient and the statistical significance (p-value) between uranyl concentrations and the other variables discussed was calculated using the function cor.test (
Tables 1,
2).
[A] Groundwater uranium distribution in Chintamani village (red boundary). [B] Local kernel density estimate (KDE) smoothing to predict area-wide uranium concentrations (in ppm, contours).
Elemental composition of TDS obtained after drying groundwater samples collected from Chintamani village.
Borewell name
Data type
C
N
O
S
Na
Mg
Si
Cl
K
Ca
Al
Rh
Borewell 1
Mean (mg/L)
162.10
40.43
361.08
8.29
34.35
35.37
11.29
64.04
1.97
68.93
0.00
0.00
(0.771 ppm U)
SD (mg/L)
15.41
4.59
23.80
5.88
16.09
3.16
2.90
15.18
0.53
9.70
0.00
0.00
Mean (%)
20.53
5.12
45.73
1.05
4.35
4.48
1.43
8.11
0.25
8.73
0.00
0.00
SD (%)
1.95
0.58
3.01
0.74
2.04
0.40
0.37
1.92
0.07
1.23
0.00
0.00
Borewell 2
Mean (mg/L)
21.29
14.07
98.55
1.73
18.27
9.23
7.53
8.71
0.52
12.45
0.00
0.00
(0.018 ppm U)
SD (mg/L)
3.21
4.63
10.94
0.49
8.33
1.56
1.59
8.71
0.19
3.96
0.00
0.00
Mean (%)
11.07
7.32
51.25
0.90
9.50
4.80
3.92
4.53
0.27
6.47
0.00
0.00
SD (%)
1.67
2.41
5.69
0.26
4.33
0.81
0.82
4.53
0.10
2.06
0.00
0.00
Borewell 3
Mean (mg/L)
68.70
3.01
80.65
0.55
17.39
0.93
3.73
2.31
0.14
5.79
0.00
0.00
(0.02 ppm U)
SD (mg/L)
8.88
1.10
5.70
0.22
4.94
0.42
2.04
1.23
0.08
4.68
0.00
0.00
Mean (%)
37.46
1.64
43.98
0.30
9.48
0.51
2.03
1.26
0.08
3.16
0.00
0.00
SD (%)
4.84
0.60
3.11
0.12
2.70
0.23
1.11
0.67
0.05
2.55
0.00
0.00
Borewell 4
Mean (mg/L)
188.21
28.61
419.15
8.58
63.44
45.35
13.63
157.83
1.51
82.96
0.25
0.00
(0.143 ppm U)
SD (mg/L)
41.52
5.70
53.89
2.94
34.20
8.07
2.94
39.23
0.91
31.75
0.87
0.00
Mean (%)
18.64
2.83
41.52
0.85
6.28
4.49
1.35
15.63
0.15
8.22
0.03
0.00
SD (%)
4.11
0.56
5.34
0.29
3.39
0.80
0.29
3.89
0.09
3.14
0.09
0.00
Borewell 5
Mean (mg/L)
75.72
55.75
268.32
4.58
29.29
21.87
11.51
36.12
3.44
41.10
0.00
0.00
(0.035 ppm U)
SD (mg/L)
33.53
4.78
31.94
8.20
21.23
4.24
3.47
21.90
0.85
14.98
0.00
0.00
Mean (%)
13.82
10.17
48.96
0.84
5.35
3.99
2.10
6.59
0.63
7.50
0.00
0.00
SD (%)
6.12
0.87
5.83
1.50
3.87
0.77
0.63
4.00
0.16
2.73
0.00
0.00
Borewell 6
Mean (mg/L)
231.15
147.59
961.15
24.77
167.33
82.09
31.7
253.2
5.88
195.88
0.00
0.00
(0.595 ppm U)
SD (mg/L)
50.25
14.1
93.99
4.31
84.42
10.23
4.52
71.37
1.51
60
0.00
0.00
Mean (%)
11.01
7.03
45.78
1.18
7.97
3.91
1.51
12.06
0.28
9.33
0.00
0.00
SD (%)
2.39
0.67
4.48
0.21
4.02
0.49
0.22
3.4
0.07
2.86
0.00
0.00
Borewell 7
Mean (mg/L)
111.31
27.57
251.16
3.85
14.06
31.91
6.57
79.94
1.57
14.98
0.00
0.00
(4.15 ppm U)
SD (mg/L)
41.24
5.52
18.57
1.47
5.17
7.76
1.87
24.42
0.36
5.11
0.00
0.00
Mean (%)
20.51
5.08
46.28
0.71
2.59
5.88
1.21
14.73
0.29
2.76
0.00
0.00
SD (%)
7.6
1.02
3.42
0.27
0.95
1.43
0.34
4.5
0.07
0.94
0.00
0.00
Borewell 8
Mean (mg/L)
91.24
47.39
331.77
10.73
43.29
37
10.38
80.01
4.03
50.42
0.00
0.00
(8.64 ppm U)
SD (mg/L)
31.86
3.37
19.24
2.06
12.97
4.26
1.22
18.42
0.63
10.59
0.00
0.00
Mean (%)
12.92
6.71
46.98
1.52
6.13
5.24
1.47
11.33
0.57
7.14
0.00
0.00
SD (%)
4.51
0.48
2.72
0.29
1.84
0.6
0.17
2.61
0.09
1.5
0.00
0.00
Borewell 9
Mean (mg/L)
103.58
54.36
316.02
9.95
51.34
26.7
12.08
67.27
1.65
40.5
0.00
3.02
(0.12 ppm U)
SD (mg/L)
56.39
10
39.49
3.09
20.6
6
3.75
27.88
0.63
13.71
0.00
9.93
Mean (%)
15.09
7.92
46.04
1.45
7.48
3.89
1.76
9.8
0.24
5.9
0.00
0.44
SD (%)
8.22
1.46
5.75
0.45
3
0.87
0.55
4.06
0.09
2
0.00
1.45
Borewell 10
Mean (mg/L)
165.78
41.3
370.31
8.11
44.08
27.87
7.26
81.16
1.69
96.95
0.00
0.00
(0.74 ppm U)
SD (mg/L)
32.51
14.35
39.66
3.48
19.81
7.44
2.11
28.41
0.72
28.74
0.00
0.00
Mean (%)
19.63
4.89
43.85
0.96
5.22
3.3
0.86
9.61
0.2
11.48
0.00
0.00
SD (%)
3.85
1.7
4.7
0.41
2.35
0.88
0.25
3.36
0.09
3.4
0.00
0.00
Borewell 11
Mean (mg/L)
251.7
0
226.54
10.41
56.57
15.45
7.85
52.87
0.77
16.47
0.00
0.00
(1.27 ppm U)
SD (mg/L)
54.04
0
78.41
11.54
31.48
8
4.96
41.63
0.76
21.52
0.00
0.00
Mean (%)
39.42
0
35.48
1.63
8.86
2.42
1.23
8.28
0.12
2.58
0.00
0.00
SD (%)
8.46
0
12.28
1.81
4.93
1.25
0.78
6.52
0.12
3.37
0.00
0.00
Borewell 12
Mean (mg/L)
84.03
45.89
445.46
16.22
37.96
36.62
11.76
82.16
2.05
129.03
0.00
0.00
(0.21 ppm U)
SD (mg/L)
32.29
7.36
43.55
13.65
31.12
7.08
3.52
32.96
0.55
43.37
0.00
0.00
Mean (%)
9.43
5.15
49.99
1.82
4.26
4.11
1.32
9.22
0.23
14.48
0.00
0.00
SD (%)
3.62
0.83
4.89
1.53
3.49
0.79
0.4
3.7
0.06
4.87
0.00
0.00
Conc. (mg
/L)
Mean (mg/L)
129.57
42.16
344.18
8.98
48.11
30.87
11.27
80.47
2.10
62.96
0.02
0.25
SD (mg/L)
70.02
38.13
224.92
6.60
40.69
20.53
7.04
67.60
1.62
56.45
0.07
0.87
Correlation
-0.27
-0.10
-0.20
-0.03
-0.25
0.05
-0.31
0.02
0.21
-0.22
-0.15
-0.16
P-value
0.39
0.75
0.53
0.92
0.42
0.87
0.32
0.95
0.5
0.48
0.63
0.62
Relative %
Mean (%)
19.13
5.32
45.49
1.10
6.46
3.92
1.68
9.27
0.28
7.31
0.00
0.04
SD (%)
9.82
2.82
4.15
0.44
2.23
1.39
0.789
4.03
0.17
3.55
0.01
0.13
Correlation
-0.1
0.06
0.03
0.22
-0.28
0.45
-0.24
0.36
0.49
-0.2
-0.15
-0.16
P-value
0.75
0.85
0.93
0.49
0.37
0.14
0.44
0.24
0.1
0.54
0.63
0.62
Chintamani groundwater datasets
Groundwater from 12 borewells in Chintamani village, Chikkaballapura District, Karnataka, India were sampled from August 2024 to December 2024. Initially, we collected groundwater samples from borewells 1-5 that were evenly distributed around the geographical area of Chintamani village. Groundwater from borewell 1 displayed the highest uranium concentration from this cohort (0.771 ppm U), leading us to sample groundwater from more borewells around borewell 1 in the northwestern region of Chintamani village. We found a statistically significant difference (p = 0.048, Welch 2-sample T-test, one-tailed) between the uranium concentration of groundwater in the northwestern region (NW, borewells 1, 6-12) compared to groundwater in the rest of Chintamani village (borewells 2-5).
Table 1 depicts uranium concentrations quantified using ICP-MS from these 12 groundwater samples. Uranium concentrations ranged from 0.018 ppm (Borewell 2) to 8.64 ppm (Borewell 8). There exists a weak correlation (r = 0.49, Pearson’s coefficient) between uranium concentration and well depth. However, the correlation is not statistically significant (p = 0.14). ICP-MS reports quantifying uranium content for each sample can be found in Supplementary Dataset S1.
20
Table 2 represents the elemental composition of the total dissolved solids (TDS) obtained after drying groundwater samples collected from Chintamani village. For each borewell water sample, we calculated correlation coefficients between the absolute and relative elemental compositions of each element and the uranium concentration. This was done in order to determine if uranium concentrations are correlated with those of other elements, suggesting co-occurrence or common geochemical behavior. The elemental composition of dried TDS was determined using SEM-EDS. Elemental composition is expressed in absolute terms (mg of element per liter of groundwater, mg
/L) and in relative terms (% composition compared to all other elements present in dried TDS). Pearson’s correlation coefficients are provided for both expressions of elemental composition by comparing the values for every element with the corresponding uranium concentration (in ppm) (refer
Table 1). It was observed that the % composition of K (r = 0.49, p = 0.1) and Mg (r = 0.45, p = 0.14) were weakly correlated with uranium concentration, although these correlations were not statistically significant. No significant correlation was observed between nitrogen and uranium concentrations, in either absolute (r = –0.10, p = 0.75) or relative (r = 0.06, p = 0.85) terms. This suggests that nitrate fertilizers are unlikely to play a role in mobilizing uranium from bedrock in Chintamani village. SEM-EDS spectra and reports quantifying the elemental composition of each sample can be found in Supplementary Dataset S2.
21
Conclusion
We have presented a dataset containing uranyl concentrations from groundwater obtained from 12 borewells across Chintamani village, Chikkaballapura district, Karnataka, India. Uranyl concentrations ranged from 0.018 ppm (borewell 2) to 8.64 ppm (borewell 8). According to World Health Organization (WHO),
9 and Atomic Energy Regulatory board (AERB) recommendations, the uranium concentration in drinking water should remain ≤30 ppb (0.03 ppm) and ≤60 ppb (0.06 ppm) respectively to minimize health risks. 10 out of the 12 borewells sampled possessed uranium concentrations >0.03 ppm, and 9 wells possessed uranium concentrations >0.06 ppm, indicating cause for concern. Uranium concentrations >0.03 ppm were observed both in the northwest region (borewells 1, 6-12) as well as outside (borewells 4, 5), indicating a wide distribution across the water table of Chintamani village. Borewell 8 possessed 8.64 ppm uranium, a concentration 288× greater than the WHO recommended maximum.
Nephrotoxicity,
10,
11 bone function impairments,
16 developmental and reproductive toxicity
17 are known adverse health effects associated with chronic uranium exposure. It is therefore worth studying the prevalence of such health effects in the residents of Chintamani village.
R Srinivasan et al.
18 previously conducted a survey on the groundwater uranium concentrations of villages in eastern Karnataka. Their study was broader in scope and sampled 73 villages. As a consequence, the samples collected per village were low. R Srinivasan et al. reported uranium concentrations of 5267 ± 6 ug/g and 5913 ± 6 uranium from 2 borewells sampled in Chintamani village. Here, we show a far greater variation in uranium concentrations, ranging from 0.018 ppm to 8.64 ppm (mean = 1.39 ±2.55 ppm), from the 12 borewells we sampled in Chintamani village. We have measured groundwater uranium concentrations using ICP-MS, which helps confirm previous fluorimetric measurements.
18 Our study provides greater insights into groundwater uranium concentrations in Chintamani village, but is nevertheless limited by our larger but still modest sample size (n=12) and lack of temporal data.
We have provided two datasets: ICP-MS data for groundwater uranium concentration (Dataset S1
19), and SEM-EDS data for the elemental compositions of TDS obtained from these groundwater samples (Dataset S2
20). These datasets, along with our kernel density estimate of groundwater uranium distributions (
Figure 1B), could potentially be used as resources for guiding remediation efforts by displaying borewells and areas possessing the highest uranium concentrations. Further work, such as direct health or exposure assessments, is required to determine the environmental and public health effect of groundwater uranium in Chintamani village and its surroundings.
Ethics and consent
Ethical consent and approval were not required.
Author contributions
Authors Sadashiva Rampur, Mahesh Kumar V.K., and Pavan R. Pelli surveyed and collected water samples from Chintamani village. Authors Senjuti Sarkar, Samayeta Pramanik, Upama Majumdar, Shravanthi S., and Bhavana Meenakshi T. processed groundwater samples to quantify TDS content, and processed samples for SEM-EDS and ICP-MS experiments. Authors Srinidhi G. Santhanakrishnan and Rushi Pendem analyzed and interpreted all data. Authors Senjuti Sarkar, Tanushree Ghosh, and Deepesh Nagarajan conceived the project and designed all experiments. All authors took part in drafting the manuscript and provided final approval before submission.
Data availability
Data are available under the terms of the
Creative Commons Attribution 4.0 International license (CC-BY 4.0). All raw data have been made publicly available for use by the research community.
Underlying data
Repository name: Dataset S1: ICP-MS data for groundwater uranium concentration in ppm.
https://doi.org/10.6084/m9.figshare.28491125.v1.
20
The project contains the following underlying data:
dataset-s1.pdf ICP-MS reports (generated by Eurofins India, Bangalore) for the uranium concentrations of groundwater samples from borewells 1-12 (reported in ppm). Water samples were collected from Chintamani village, Chikkaballapura district, Karnataka, India, during the period of August 2024 to December 2024.
The project contains the following underlying data:
dataset-s2.pdf SEM-EDS spectra and reports (generated by Icon Labs Pvt. Ltd., Mumbai) for the elemental composition of total dissolved solids (TDS) obtained after drying groundwater samples from borewells 1-12. Water samples were collected from Chintamani village, Chikkaballapura district, Karnataka, India, during the period of August 2024 to December 2024.
Acknowledgements
The authors extend their thanks to Mr. Kiran Rambhau Bhotkar (Assistant Manager - Application Support, SEM-EDS) and Mrs. Sunita Samgir (Senior Executive - Application Support, SEM-EDS) from Icon Labs Pvt. Ltd., Mumbai, for their excellent work as our scanning electron microscopy technicians.
ReferencesAyotteJDFlanaganSMMorrowWS:
Occurrence of uranium and 222radon in glacial and bedrock aquifers in the northern United States, 1993-2003.US Department of the Interior, US Geological Survey;2007.ChurchillR:
Geologic controls on the distribution of radon in california.USA:
The Department of Health Services;1991.AdamsJASKenneth OsmondJRogersJJW:
The geochemistry of thorium and uranium.Phys. Chem. Earth.1959;3:298–348.
10.1016/0079-1946(59)90008-4SchnugELottermoserBG:
Fertilizer-derived uranium and its threat to human health.2013.JurgensBCFramMSBelitzK:
Effects of groundwater development on uranium: Central Valley, California, USA.Groundwater.2010;48(6):913–928.
1978855910.1111/j.1745-6584.2009.00635.xYaWWangYXieX:
Occurrence, behavior and distribution of high levels of uranium in shallow groundwater at Datong basin, northern China.Sci. Total Environ.2014;472:809–817.
10.1016/j.scitotenv.2013.11.109EFS Authority:
Uranium in foodstuffs, in particular mineral water.EFSA J.2009;7:1018.
10.2903/j.efsa.2009.1018NriaguJNamD-HAyanwolaTA:
High levels of uranium in groundwater of Ulaanbaatar, Mongolia.Sci. Total Environ.2012;414:722–726.
2214264610.1016/j.scitotenv.2011.11.037PMC3258323ChenLLiuJZhangW:
Uranium (U) source, speciation, uptake, toxicity and bioremediation strategies in soil-plant system: A review.J. Hazard. Mater.2021;413:125319.
3358247010.1016/j.jhazmat.2021.125319ShtangeevaI:
14 Uranium and Thorium Accumulation in Cultivated Plants.Trace elements as contaminants and nutrients:
Consequences in ecosystems and human health;2008; p.295.
10.1002/9780470370124.ch14NordbergGFCostaM:
Handbook on the toxicology of metals: volume II: Specific Metals.Academic Press;2021.ChoB-WKimD-SKimM-S:
Hydrogeochemical characteristics of uranium and radon in groundwater from the Goesan area of the Ogcheon metamorphic belt (OMB), Korea.Sustainability.2021;13(20):11261.
10.3390/su132011261Vicente-VicenteLQuirosYPérez-BarriocanalF:
Nephrotoxicity of uranium: pathophysiological, diagnostic and therapeutic perspectives.Toxicol. Sci.2010;118(2):324–347.
2055469810.1093/toxsci/kfq178SeldénAILundholmCEdlundB:
Nephrotoxicity of uranium in drinking water from private drilled wells.Environ. Res.2009;109(4):486–494.
1927867610.1016/j.envres.2009.02.002KurttioPAuvinenASalonenL:
Renal effects of uranium in drinking water.Environ. Health Perspect.2002;110(4):337–342.
1194045010.1289/ehp.02110337PMC1240795ArzuagaXGehlhausMStrongJ:
Modes of action associated with uranium induced adverse effects in bone function and development.Toxicol. Lett.2015;236(2):123–130.
2597611610.1016/j.toxlet.2015.05.006DomingoJL:
Reproductive and developmental toxicity of natural and depleted uranium: a review.Reprod. Toxicol.2001;15(6):603–609.
1173851310.1016/S0890-6238(01)00181-2SrinivasanRPanditSAKarunakaraN:
High uranium concentration in groundwater used for drinking in parts of eastern Karnataka, India.Curr. Sci.2021;121(11):1459–1469.
10.18520/cs/v121/i11/1459-1469Central Ground Water Board:
Report on Uranium in Ground Water (2019–20).Government of India, Ministry of Jal Shakti, Department of Water Resources, River Development and Ganga Rejuvenation;2020.NagarajanD:
Dataset S1: ICP-MS data for groundwater uranium concentration in ppm.Figshare.2025.
10.6084/m9.figshare.28491125.v1NagarajanD:
Dataset S2: SEM-EDS spectra of groundwater TDS.Figshare.2025.
10.6084/m9.figshare.28491146.v1ChengJKarambelkarBXieY:
Package ‘leaflet’.R package version.2019;2(1).10.5256/f1000research.185995.r407690Reviewer response for version 3MisraNilanjal1Refereehttps://orcid.org/0000-0002-6267-7362
Bhabha Atomic Research Centre, Trombay, India
Competing interests: No competing interests were disclosed.
Are sufficient details of methods and materials provided to allow replication by others?
Partly
Is the rationale for creating the dataset(s) clearly described?
Partly
Are the datasets clearly presented in a useable and accessible format?
Partly
Are the protocols appropriate and is the work technically sound?
Partly
Reviewer Expertise:
Development of environmentally sustainable technologies for heavy metal ion remediation in ground water
I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.
10.5256/f1000research.182340.r399030Reviewer response for version 2MisraNilanjal1Refereehttps://orcid.org/0000-0002-6267-7362
Bhabha Atomic Research Centre, Trombay, India
Competing interests: No competing interests were disclosed.
Although the work is well intended, the data set presented is relatively small and concentrated to a particular zone to draw any significant conclusions about the pattern of U concentration distribution in the region. The determination of elemental composition and its impact on the actual objective of the study is not well defined. Since the authors have mentoned that nitrate based fertilizers are responsible for solubilizing U from bed-rocks, a corelation between the N content of the samples and the U content can be discussed briefly. The authors can specifiy how many samples from each borewell have been analyzed and provide the mean U concentration for each borewell along with respective SD.
Are sufficient details of methods and materials provided to allow replication by others?
Partly
Is the rationale for creating the dataset(s) clearly described?
Partly
Are the datasets clearly presented in a useable and accessible format?
Partly
Are the protocols appropriate and is the work technically sound?
Partly
Reviewer Expertise:
Development of environmentally sustainable technologies for heavy metal ion remediation in ground water
I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.
NagarajanDeepesh
Competing interests: No competing interests were disclosed.
1482025
AUTHOR RESPONSE: We thank the reviewer for raising important issues in his review, and have addressed all his concerns below:
Although the work is well intended, the data set presented is relatively small and concentrated to a particular zone to draw any significant conclusions about the pattern of U concentration distribution in the region.
AUTHOR RESPONSE: We agree with the reviewer. We can only draw conclusions about the pattern of U concentration within and immediately surrounding Chintamani village (the zone of this study). In the manuscript, we have not drawn any conclusions about the pattern of U concentration in the Eastern Karnataka region.
The determination of elemental composition and its impact on the actual objective of the study is not well defined.
AUTHOR RESPONSE: For each borewell water sample, we calculated correlation coefficients between the absolute and relative elemental compositions of each element and the uranium concentration. This was done in order to determine if uranium concentrations are correlated with those of other elements, suggesting co-occurrence or common geochemical behavior.
This is now mentioned in
paragraph 3 of the ‘
Chintamani groundwater datasets’ section.
In Table 2, we have provided correlation coefficients for both the absolute concentrations and relative % of every element observed, compared to uranium concentration. We observed no strong, statistically significant correlation coefficients for any element. We only observed weak correlations between U and K/Mg. Nevertheless, we have made the raw data available to the research community in Dataset S2, for other groups to analyze.
Since the authors have mentioned that nitrate based fertilizers are responsible for solubilizing U from bed-rocks, a correlation between the N content of the samples and the U content can be discussed briefly.
AUTHOR RESPONSE: No significant correlation was observed between nitrogen and uranium concentrations, in either absolute (r = –0.10, p = 0.75) or relative (r = 0.06, p = 0.85) terms. This suggests that nitrate fertilizers are unlikely to play a role in mobilizing uranium from bedrock in Chintamani village.
This is now mentioned in
paragraph 3 of the ‘
Chintamani groundwater datasets’ section.
The authors can specifiy how many samples from each borewell have been analyzed and provide the mean U concentration for each borewell along with respective SD.
AUTHOR RESPONSE: As we have estimated uranium concentration using ICP-MS, which has a low margin of error (1-3%), only one sample per borewell was required. Furthermore, due to funding constraints, we were only able to conduct a finite number of measurements. Measuring uranium concentration repeatedly for a single well would decrease the total number of wells sampled.
In
Table 1, we have provided the mean/SD of uranium concentrations across all borewells in Chintamani village.
10.5256/f1000research.182340.r383555Reviewer response for version 2O. OmokpariolaDaniel1Refereehttps://orcid.org/0000-0003-1360-4340
Nnamdi Azikiwe University, Awka, Anambra, Nigeria
Competing interests: No competing interests were disclosed.
Please find the attached work and review them for further modification
1. Scope and Novelty
a. The study is confirmatory and does not clearly articulate what new insights it offers beyond previous surveys.
b. The authors should clarify:
i. Why this specific location was chosen.
ii. Whether the data updates or expands on previous findings.
iii. How this dataset can inform remediation or policy decisions.
2. Scientific Context
a. The introduction should include:
i. A clearer rationale for repeating uranium measurements in this region.
ii. A brief overview of potential exposure pathways (e.g., drinking water, food chain).
iii. A summary of known health risks from uranium exposure (e.g., nephrotoxicity, reproductive effects).
3. Interpretation of Results
a. The conclusion is too brief and lacks interpretation.
b. The authors should describe the spatial distribution of uranium (e.g., “localized in the NW region”).
c. Discuss whether the observed concentrations exceed WHO or Indian drinking water standards.
d. Highlight any environmental or public health implications.
4. Methodological Clarifications
a. The “Sample collection” section should include:
i. GPS coordinates of all borewells (only partially included in Table 1).
ii. Clarification on how borewells were selected (random, purposive, based on prior data?).
iii. The use of “t.test()” in the text should be corrected or explained more clearly.
5. Data Presentation
a. The tables are comprehensive but dense.
b. Consider summarizing key findings in a visual format (e.g., heatmap, scatter plot).
c. Highlight borewells that exceed safety thresholds.
d. A spatial map showing uranium concentration gradients would enhance clarity.
6. Language and Style
Minor grammatical and typographical issues should be corrected:
Example: “Forevery” → “For every”
Example: “hot-air ovenat” → “hot-air oven at”
Example: “t.test()” → should be formatted correctly or described in plain language.
Further Suggestions
To enhance the manuscript’s scientific value and clarity:
a. Expand the conclusion to include:
b. A summary of spatial trends.
c. Implications for public health or groundwater management.
d. Recommendations for future research or monitoring.
e. Add a brief section on limitations:
f. Small sample size (12 borewells).
g. Lack of temporal data (single sampling period).
h. No direct health or exposure assessment.
Include a visual summary (e.g., map or infographic) to improve accessibility.
Are sufficient details of methods and materials provided to allow replication by others?
Partly
Is the rationale for creating the dataset(s) clearly described?
Yes
Are the datasets clearly presented in a useable and accessible format?
Yes
Are the protocols appropriate and is the work technically sound?
Yes
Reviewer Expertise:
Environmental Chemistry and Toxicology; Remote Sensing; Atmospheric and Water chemistry; Risk assessment and Project Management
I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.
NagarajanDeepesh
Competing interests: The authors declare no competing interests.
182025
Dear Authors,
Please find the attached work and review them for further modification
AUTHOR RESPONSE: We thank the reviewer for his expert comments, and have addressed all the concerns raised below.
1. Scope and Novelty
a. The study is confirmatory and does not clearly articulate what new insights it offers beyond previous surveys.
b. The authors should clarify:
i. Why this specific location was chosen.
AUTHOR RESPONSE: The site selection was based on accessibility and its proximity to our university. We have now mentioned this in the Introduction section of the manuscript.
ii. Whether the data updates or expands on previous findings.
AUTHOR RESPONSE: The data confirms and expands on previous findings due to our larger sample size (n=12), spatial groundwater uranium map withing Chintamai village (Figure 1), and the use of a more rigorous method (ICP-MS) to quantify groundwater concentrations.
iii. How this dataset can inform remediation or policy decisions.
AUTHOR RESPONSE: The raw data along with our kernel density estimate (Figure 1) of groundwater uranium concentrations divides Chintamani village into groundwater zones possessing different groundwater uranium concentrations. Borewells and areas possessing higher groundwater uranium concentrations may be assigned a higher priority for remediation. This is now mentioned in the conclusion section.
“ These datasets along with our kernel density estimate of groundwater uranium distributions (FIgure 1B) could potentially be used as resources for prioritizing guiding remediation efforts by displaying borewells and areas possessing the highest uranium concentrations. “
2. Scientific Context
a. The introduction should include:
i. A clearer rationale for repeating uranium measurements in this region
.
AUTHOR RESPONSE: We have elaborated on our rationale in the Introduction (paragraph 5).
ii. A brief overview of potential exposure pathways (e.g., drinking water, food chain).
AUTHOR RESPONSE: We have outlined uranium exposure routes in the Introduction (paragraph 3 and 4).
Introduction paragraph 3: Uranium adversely affects crops grown on soil irrigated with contaminated groundwater. Uranium’s phytotoxic effects include inhibition of photosynthesis, inhibition of plant growth, protein and lipid membrane oxidation, overproduction of reactive oxygen species, and DNA breakage [9]. Uranium primarily accumulates in root systems, with negligible amounts found in aerial parts of plants [10] and is therefore a greater concern for root and tuber crops.
Introduction paragraph 4: Dermal exposure results in minimal toxicity, particularly if Uranium is in an insoluble form [11]. Uranium in groundwater is typically present as sparingly soluble uranyl carbonate complexes [12], minimizing the risk of absorption through the dermal route. Instead, oral consumption of uranium through drinking untreated uranium-contaminated groundwater is of more concern.
iii. A summary of known health risks from uranium exposure (e.g., nephrotoxicity, reproductive effects).
AUTHOR RESPONSE: We have outlined the health risks associated with uranium exposure in the Introduction (paragraph 5).
Introduction paragraph 5: Although uranium is weakly radioactive, its primary health risk stems from its chemical toxicity rather than its radioactivity. Chronic exposure to uranium-contaminated water is associated with nephrotoxicity [14
, 15], with adverse renal effects reported in both laboratory animals and humans [16]. Uranium excretion in urine is correlated with phosphate and calcium excretion [16]. Other adverse effects include inhibition of bone function and development [17], reproductive and developmental toxicity [18].
3. Interpretation of Results
a. The conclusion is too brief and lacks interpretation.
AUTHOR RESPONSE: We have expanded the conclusion section to discuss the scope, novelty, and utility of our data.
b. The authors should describe the spatial distribution of uranium (e.g., “localized in the NW region”).
AUTHOR RESPONSE: We have provided a kernel density estimate of the groundwater uranium
concentrations in and around Chintamani village (Figure 1B) that quantifies the spatial distribution of uranium.
c. Discuss whether the observed concentrations exceed WHO or Indian drinking water standards.
AUTHOR RESPONSE: We have discussed this in the Conclusion section (paragraph 1):
Conclusion paragraph 1: According to World Health Organization (WHO) recommendations [
9] and Atomic Energy Regulatory board (AERB) recommendations, the uranium concentration in drinking water should remain ≤30 ppb (0.03 ppm) and ≤60 ppb (0.06 ppm) respectively to minimize health risks. 10 out of the 12 borewells sampled possessed uranium concentrations >0.03 ppm and 97 wells possessed uranium concentrations with >,0.06 ppm, indicating cause for concern. Uranium concentrations >0.03 ppm were observed both in the northwest region (borewells 1,6-12) as well as outside (borewells 4,5), indicating a wide distribution across the water table of Chintamani village. Borewell 8 possessed 8.64 ppm uranium, a concentration 288× greater than the WHO recommended maximum.
d. Highlight any environmental or public health implications.
AUTHOR RESPONSE: Currently, this study does not report the environmental or public health effects of groundwater uranium in Chintamani village. We believe that further environmental / patient data from Chintamani village needs to be collected before commenting on these issues. We have mentioned this in the Conclusion (paragraph 4)
Conclusion paragraph 4: Further work is required to determine the environmental and public health effect of groundwater uranium in Chintamani village and its surroundings.
4. Methodological Clarifications
a. The “Sample collection” section should include:
i. GPS coordinates of all borewells (only partially included in Table 1).
AUTHOR RESPONSE: Latitudes and longitudes for all 12 samples are included in Table 1.
ii. Clarification on how borewells were selected (random, purposive, based on prior data?).
AUTHOR RESPONSE: Borewells were initially randomly selected across the area in and around Chintamani village. Further samples were collected from the area around the borewell possessing the highest uranium concentration (Borewell 1). This has now been mentioned in the Introduction (paragraph 5) and Datasets section (paragraph 1).
Introduction paragraph 5: “In this data note, we report data obtained from five randomly selected borewells in Chintamani village, Chikkaballapura District, Karnataka, India. Subsequently, seven additional borewells were selected in the vicinity of the borewell exhibiting the highest uranium concentration among the initial five. “
Datasets paragraph 1: Groundwater from 12 borewells in Chintamani village, Chikkaballapura District, Karnataka, India were sampled from August 2024 to December 2024. Initially, we collected groundwater samples from borewells 1-5 that were evenly distributed around the geographical area of Chintamani village. Groundwater from borewell 1 displayed the highest uranium con- centration from this cohort (0.771 ppm U), leading us to sample groundwater from more borewells around borewell 1 in the northwestern region of Chintamani village.
iii. The use of “t.test()” in the text should be corrected or explained more clearly.
AUTHOR RESPONSE: We have corrected
t.test() to
t.test and also provided a short explanation in the Methods subsection “Data representation and statistical analyses”.
An explanation of the t.test function is provided in the same subsection, immediately before t.test is mentioned.
“The
Welch 2-sample T-test (one-tailed) was used to determine whether there existed a statistically significant difference between uranyl concentrations in different spatial locations in Chintamani village (Figure
1). This was performed using the function t.test. “
5. Data Presentation
a. The tables are comprehensive but dense.
Author response provided under query 5d:
b. Consider summarizing key findings in a visual format (e.g., heatmap, scatter plot).
Author response provided under query 5d:
c. Highlight borewells that exceed safety thresholds.
AUTHOR RESPONSE: 10 of the 12 borewells possessed uranium concentrations exceeding the World Health Organization (WHO) recommendation ≤0.03 ppm U). 9 of 12 borewells exceeded the atomic energy regulatory board (AERB) recommendation of (≤0.06 ppm U). We have highlighted these borewells in Table 1 (in bold and underlined font). To avoid visual clutter, we have only highlighted these wells in Table 1 and not in Figure 1A or 1B.
d. A spatial map showing uranium concentration gradients would enhance clarity.
AUTHOR RESPONSE for 5a, 5b, and 5d: We agree that the Tables 1 and 2 are very information dense. Our key findings are reported in Table 1 (groundwater uranium concentration for each borewell). We have now depicted this data in a visual format. We have added a local kernel density estimate (KDE) smoothing to predict area-wide uranium concentrations. This data is provided in Figure 1B.
6. Language and Style
Minor grammatical and typographical issues should be corrected:
Example: “Forevery” → “For every”
AUTHOR RESPONSE: All instances of “forevery” have been changed to “for every” in the manuscript.
Example: “hot-air ovenat” → “hot-air oven at”
AUTHOR RESPONSE: We have corrected this statement in the Methods subsection “Total dissolved solids (TDS) quantification”. It now reads:
For every borewell sample, 1 L of water was dried in a hot-air oven at 80◦C in a clean
Borosil® borosilicate 1L glass beaker until only the salt residue remained. “
Example: “t.test()” → should be formatted correctly or described in plain language.
AUTHOR RESPONSE: We have corrected
t.test() to
t.test and also provided a short explanation in the Methods subsection “Data representation and statistical analyses”. An explanation of the t.test function is provided in the same subsection, immediately before t.test is mentioned.
“The
Welch 2-sample T-test (one-tailed) was used to determine whether there existed a statistically significant difference between uranyl concentrations in different spatial locations in Chintamani village (Figure
1). This was performed using the function t.test. “
Further Suggestions
To enhance the manuscript’s scientific value and clarity:
a. Expand the conclusion to include:
b. A summary of spatial trends.
AUTHOR RESPONSE: The conclusion (paragraph 1) now contains a summary of spatial trends.
c. Implications for public health or groundwater management.
d. Recommendations for future research or monitoring.
AUTHOR RESPONSE to c/d: The conclusion (paragraph 4) now touches upon this issue. Further work is required before making public health recommendations.
e. Add a brief section on limitations:
f. Small sample size (12 borewells).
g. Lack of temporal data (single sampling period).
h. No direct health or exposure assessment.
AUTHOR RESPONSE to e/f/g/h: We have addressed these limitations in the conclusion, paragraphs 4 and 5:
Conclusion (paragraph 4): Our study provides greater insights into groundwater uranium concentrations in Chintamani village, but is nevertheless limited by our larger but still modest sample size (n=12) and lack of temporal data.
Conclusion (paragraph 5): Further work, such as direct health or exposure assessments, is required to determine the environmental and public health effect of groundwater uranium in Chintamani village and its surroundings.
Include a visual summary (e.g., map or infographic) to improve accessibility.
AUTHOR RESPONSE: We have provided a visual summary in Figure 1B.
10.5256/f1000research.178738.r376222Reviewer response for version 1OwonikokoWasiu Mathew1Refereehttps://orcid.org/0000-0002-4868-9455
Igbinedion University, Okada, Nigeria
Competing interests: No competing interests were disclosed.
The work titled “The distribution of groundwater uranium in Chintamani village, Karnataka, India” assessed the groundwater abundance of uranium in Chintamani village in India. The study is well-written with very minimal error and data well analyzed and interpreted. The comments of the reviewer, resolved along minor and major lines, are as stated below
Minor comment
Under “Sample collection” in “Material and method” section, the coordinates/GPS location of the site should be provided
“t.test()” in the second sentence of the first line in page 7 should be written correctly and the bracket filled or removed
The conclusion should be beefed up to include information on the observed nature of the distribution of uranium in the village. i.e The distribution is of uranium in the village should be properly described. Is is widespread, low or high with the possible and attendant environmental and systemic implications, authors should state.
Authors agreed that groundwater uranium concentration had been reported in India but did not impress why such investigation is being repeated within the same Country. Is the extant data now old, in a different area from the location of the last report or for merely confirmatory purpose?
Major comment
The audience of this journal may consider the scope of the study limited. Authors, in the introduction section, agreed that the study is confirmatory; implying that the observation in this study is not new and has been earlier reported. As an advancement of previous report, it will be expected that authors add more information that answer vital questions such as:
1. What is/are the possible exposure pathways to ground water uranium among humans and animals.
2. What is the health risk associated with the exposure to uranium particularly via the gastrointestinal and dermal routes?
3. What is the systemic toxicological implication of the exposure to uranium
Are sufficient details of methods and materials provided to allow replication by others?
Partly
Is the rationale for creating the dataset(s) clearly described?
Yes
Are the datasets clearly presented in a useable and accessible format?
Yes
Are the protocols appropriate and is the work technically sound?
Yes
Reviewer Expertise:
Environmental Physiology and Toxicology
I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.
NagarajanDeepesh
Competing interests: The authors declare no competing interests.
1952025
The work titled “The distribution of groundwater uranium in Chintamani village, Karnataka, India” assessed the groundwater abundance of uranium in Chintamani village in India. The study is well-written with very minimal error and data well analyzed and interpreted. The comments of the reviewer, resolved along minor and major lines, are as stated below
AUTHOR RESPONSE: We thank the reviewer for his encouraging comments, and have addressed all his comments below.
Minor comment
Under “Sample collection” in “Material and method” section, the coordinates/GPS location of the site should be provided
AUTHOR RESPONSE: We have provided the coordinates (latitude / longitude) for every sample in Table 1. We have now referred to Table in the
sample collection section. “
Table 1 lists the latitude, longitude, and date of collection for every sample.”
“t.test()” in the second sentence of the first line in page 7 should be written correctly and the bracket filled or removed
AUTHOR RESPONSE: We agree with the reviewer and have removed the () in t.test. The sentence now reads: “
This was performed using the function t.test”
The conclusion should be beefed up to include information on the observed nature of the distribution of uranium in the village. i.e The distribution is of uranium in the village should be properly described. Is it widespread, low or high with the possible and attendant environmental and systemic implications, authors should state.
AUTHOR RESPONSE: We agree with the reviewer and have added the following material to the
conclusion, discussing the distribution and systemic health effects of uranium:
Uranyl concentrations ranged from 0.018 ppm (borewell 2) to 8.64 ppm (borewell 8). According to World Health Organization (WHO) recommendations, uranium concentration in drinking water should remain ≤30 ppb (0.03 ppm) to minimize health risks. 10 out of the 12 borewells sampled possessed uranium concentrations >0.03 ppm, indicating cause for concern. Uranium concentrations >0.03 ppm were observed both in the northwest region (borewells 1,6-12) as well as outside (borewells 4,5), indicating a wide distribution across the water table of Chintamani village. Borewell 8 possessed 8.64 ppm uranium, a concentration 288× greater than the WHO recommended maximum.
Nephrotoxicity, bone function impairments, developmental and reproductive toxicity are known adverse health effects associated with chronic uranium exposure. It is therefore worth studying the prevalence of such health effects in the residents of Chintamani village.
Authors agreed that groundwater uranium concentration had been reported in India but did not impress why such investigation is being repeated within the same Country. Is the extant data now old, in a different area from the location of the last report or for merely confirmatory purposes?
AUTHOR RESPONSE: We thank the reviewer for raising an important point. R. Srinivasan et al. (reference 19) previously reported high uranium concentrations in groundwater in parts of eastern Karnataka (a state in India). Their study was broad in scope, reporting uranium concentrations from 73 separate villages in the state. Due to the broad scope, only 1-2 samples per village were collected. The authors did not report the exact location of sample collection for every village.
Our study is narrower in scope, as we survey the spatial distribution of groundwater uranium concentration in a single village (Chintamani). We show that uranium concentrations in groundwater can greatly vary even within the water table of a single village. R. Srinivasan et al. reported uranium concentrations of 5267 ± 6 ug/g and 5913 ± 6 uranium from 2 borewells sampled in Chintamani. Here, we show a far greater variation in uranium concentrations, ranging from 0.018 ppm to 8.64 ppm (mean = 1.39 ±2.55 ppm), from the 12 borewells we sampled in Chintamani.
Our two studies therefore have different scopes and complement each other. This has now been mentioned in the
Conclusion section.
Major comment
The audience of this journal may consider the scope of the study limited. Authors, in the introduction section, agreed that the study is confirmatory; implying that the observation in this study is not new and has been earlier reported. As an advancement of previous report, it will be expected that authors add more information that answer vital questions such as:
1. What is/are the possible exposure pathways to ground water uranium among humans and animals.
AUTHOR RESPONSE: We thank the reviewer for raising an important point. As Chintamani is an agricultural village, we believe it’s pertinent to discuss uranium uptake in plants in addition to animals and humans. We have now discussed these issues in the
introduction section.
2. What is the health risk associated with the exposure to uranium particularly via the gastrointestinal and dermal routes
?
AUTHOR RESPONSE: Dermal exposure results in minimal toxicity, particularly if Uranium is in an insoluble form. Uranium in groundwater is typically present as sparingly soluble uranyl carbonate, minimizing the risk of absorption through the dermal route.
Oral consumption of uranium leads to nephrotoxicity, inhibition of bone function and development, reproductive and developmental toxicity. These points are now discussed in the
introduction section.
3. What is the systemic toxicological implication of the exposure to uranium?
AUTHOR RESPONSE: Oral consumption of uranium-contaminated groundwater leads to systemic toxicological effects: nephrotoxicity, inhibition of bone function and development, reproductive and developmental toxicity. These points are discussed in the
introduction section alongside health risks associated with oral consumption (previous comment).
AUTHOR RESPONSE: The relevant excerpt for the introduction section covering
Major comment points 1-3 is provided below:
Uranium adversely affects crops grown on soil irrigated with contaminated groundwater. Uranium’s phytotoxic effects include inhibition of photosynthesis, inhibition of plant growth, protein and lipid membrane oxidation, overproduction of reactive oxygen species, and DNA breakage. Uranium primarily accumulates in root systems, with negligible amounts found in aerial parts of plants and is therefore a greater concern for root and tuber crops.
Dermal exposure results in minimal toxicity, particularly if Uranium is in an insoluble form. Uranium in groundwater is typically present as sparingly soluble uranyl carbonate complexes, minimizing the risk of absorption through the dermal route. Insteal, oral consumption of uranium through drinking untreated uranium-contaminated groundwater is of more concern. The World Health Organization (WHO) recommends a maximum uranium concentration of 30 ppb in drinking water to minimize health risks. Although uranium is weakly radioactive, its primary health risk stems from its chemical toxicity rather than its radioactivity. Chronic exposure to uranium-contaminated water is associated with nephrotoxicity, with adverse renal effects reported in both laboratory animals and humans. Uranium excretion in urine is correlated with phosphate and calcium excretion. Other adverse effects include inhibition of bone function and development, reproductive and developmental toxicity.
Is the rationale for creating the dataset(s) clearly described?
Yes
Are the protocols appropriate and is the work technically sound?
Yes
Are sufficient details of methods and materials provided to allow replication by others?
Partly
Are the datasets clearly presented in a useable and accessible format?
Yes
Competing Interests
No competing interests were disclosed.
Reviewer Expertise
Environmental Physiology and Toxicology
I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.
AUTHOR RESPONSE: We thank the reviewer for his meticulous feedback, and we hope to have addressed all the concerns raised in this response.