F1000ResearchF1000Research2046-1402F1000 Research LimitedLondon, UK10.12688/f1000research.162525.1Data NoteArticlesThe distribution of groundwater uranium in Chintamani village, Karnataka, India
[version 1; peer review: 1 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. Ge- ologically, 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 de- pletion 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 0.02 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.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
The World Health Organization (WHO) recommends a maximum uranium concentration of 30 ppb in drinking water to minimize health risks.
9 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,
10,
11 adverse effects on bone function and development,
12 reproductive and developmental toxicity.
13
In this data note, we report data obtained from 12 borewells in Chintamani village, Chikkaballapura District, Karnataka, India. We report the uranyl concentrations (ICP-MS), and TDS elemental compositions (SEM-EDS) of groundwater obtained from all the wells sampled. A previous survey reported high concentrations of groundwater uranium from 73 borewells spread across 13 districts of Eastern Karnataka,
14 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 migmaties.
14 The borewells we sampled displayed uranium concentrations ranging from 0.02 ppm to 8.64 ppm, confirming the concentration ranges reported in the previous survey. Furthermore, we report spatial localization of groundwater uranium. We observed significant differences in the distribution of uranium concentrations within the local water table. 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.
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.
15
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.
16
Data representation and statistical analyses
All statistical analyses were performed using the
R programming language (version 4.4.2). The
Leaflet package17 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).
Groundwater uranium distribution in Chintamani village (red boundary).
Uranium concentrations (in ppm) for groundwater collected from Chintamani village.
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
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 con- centrations ranged from 0.02 ppm (Borewell 3) 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.
15
Table 2 represents the elemental composition of the total dissolved solids (TDS) obtained after drying groundwater samples collected from Chintamani village. 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. SEM-EDS spectra and reports quantifying the elemental composition of each sample can be found in Supplementary Dataset S2.
16
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). We have also provided a dataset of the elemental compositions of TDS obtained from these groundwater samples. These datasets could potentially be used as resources for guiding remediation efforts in this region.
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.
15
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.
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Package ‘leaflet’.R package version.2019;2(1).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.