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. 2023 Jun 30;13(1):10614.
doi: 10.1038/s41598-023-36580-9.

Spatial distribution, sources and health risk assessment of heavy metals in topsoil around oil and natural gas drilling sites, Andhra Pradesh, India

Keshav Krishna Aradhi  1   2 , Babu Mallesh Dasari  3   4 , Dasaram Banothu  3 , Satyanarayanan Manavalan  3   4
Affiliations

Spatial distribution, sources and health risk assessment of heavy metals in topsoil around oil and natural gas drilling sites, Andhra Pradesh, India

Keshav Krishna Aradhi et al. Sci Rep. .

Abstract

Soils are usually the interface between human activity and environmental components that must be conserved and protected. As a result of rising industrialization and urbanization, activities such as exploration and extraction operations lead to the release of heavy metals into the environment. This study presents distribution of six heavy metals (As, Cr, Cu, Ni, Pb and Zn) in 139 top soil samples collected in and around oil and natural gas drilling sites at a sampling density of 1 site/12 km2. The results indicated the concentration ranged from 0.1 to 16 mg/kg for As, 3-707 mg/kg for Cr, 7-2324 mg/kg for Cu, 14-234 mg/kg for Ni, 9-1664 mg/kg for Pb, and 60-962 mg/kg for Zn. The contamination of soil was estimated on the basis of Index of geo accumulation (Igeo), enrichment factor (Ef), and contamination factor (Cf). Further, spatial distribution pattern maps indicated that the pollution levels for Cu, Cr, Zn, and Ni were higher around drilling sites of the study area relative to other regions. Using exposure factors for the local population and references from the USEPA's integrated database, potential ecological risk indices (PERI) and health risk assessments were made. The hazard index (HI) values of Pb (in adults) and Cr, Pb (in children) exceeded the recommended limit of HI = 1, indicating the non-carcinogenic risks. Total carcinogenic risk (TCR) calculations revealed Cr (in adults) and As, Cr (in children) levels in soils exceeded the threshold value of 1.0E - 04, indicating significant carcinogenic risk due to high metal concentrations in the study area. These results may assist in determining the soil's present state and its effect due to extraction strategies used during drilling process and initiate few remedial techniques, particularly for proper management strategies in farming activities to decrease point and non-point source of contamination.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
Sample location map of the study area (maps were generated with software ArcGIS 10.7 http://www.esri.com).
Figure 2
Figure 2
Geology map of the study area (maps were generated with software ArcGIS 10.7 http://www.esri.com).
Figure 3
Figure 3
Spatial distribution of heavy metals (a) As;(b) Cr; (c) Cu; (d) Ni; (e) Pb; (f) Zn in soils. (maps were generated with software ArcGIS 10.7 http://www.esri.com).
Figure 4
Figure 4
Spatial distribution of geo accumulation index of heavy metals in soils (maps were generated with software ArcGIS 10.7 http://www.esri.com).
Figure 5
Figure 5
Spatial distribution of enrichment factor of heavy metals in soils (maps were generated with software ArcGIS 10.7 http://www.esri.com).
Figure 6
Figure 6
Spatial distribution of contamination factor of heavy metals in soils (maps were generated with software ArcGIS 10.7 http://www.esri.com).
Figure 7
Figure 7
Spatial distribution of Potential Ecological Risk Index (PERI) & Risk Index (RI) (maps were generated with software ArcGIS 10.7 http://www.esri.com).
Figure 8
Figure 8
Spatial distribution of non-carcinogenic health risk due to heavy metals in Adult (male) (maps were generated with software ArcGIS 10.7 http://www.esri.com).
Figure 9
Figure 9
Spatial distribution of non-carcinogenic health risk due to heavy metals in Adult (female) (maps were generated with software ArcGIS 10.7 http://www.esri.com).
Figure 10
Figure 10
Spatial distribution of non-carcinogenic health risk due to heavy metals in. Children (male) (maps were generated with software ArcGIS 10.7 http://www.esri.com).
Figure 11
Figure 11
Spatial distribution of non-carcinogenic health risk due to heavy metals in Children (female) (maps were generated with software ArcGIS 10.7 http://www.esri.com).
Figure 12
Figure 12
Spatial distribution of carcinogenic health risk due to As, Cr & Pb in Adult (male & female) (maps were generated with software ArcGIS 10.7 http://www.esri.com).
Figure 13
Figure 13
Spatial distribution of carcinogenic health risk due to As, Cr & Pb in Children (male& female) (maps were generated with software ArcGIS 10.7 http://www.esri.com).
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