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. 2025 Aug 6;197(9):986.
doi: 10.1007/s10661-025-14436-1.

Occurrence, concentration, and risk assessment of selected pharmaceuticals in representative cropland soils and their underlying groundwater in Gauteng province, South Africa

Matome Peter Ngoetjana  1 , Eyob Habte Tesfamariam  2 , Sally Brown  3 , Madelien Wooding  4 , Matthys Alois Dippenaar  5
Affiliations

Occurrence, concentration, and risk assessment of selected pharmaceuticals in representative cropland soils and their underlying groundwater in Gauteng province, South Africa

Matome Peter Ngoetjana et al. Environ Monit Assess. .

Abstract

Traceable levels of pharmaceuticals are frequently detected in various environmental matrices. However, studies investigating the occurrence of pharmaceuticals in cropland soils and underlying groundwaters are relatively limited, hindering risk assessments. This study aims the following: (1) determine the occurrence of selected pharmaceuticals in cropland soils and underlying groundwater, (2) investigate the correlations between pharmaceutical's occurrence in cropland soils and underlying groundwater, (3) evaluate the correlations between soil and water parameters and pharmaceutical's concentration, and (4) estimate human health risk from pharmaceuticals present in groundwater. A single soil and groundwater sampling campaign was conducted across eighteen farmers' fields, characterized by varying farm management practices. Caffeine, carbamazepine-10,11-epoxide, carbamazepine diol, and N4-acetylsulfamethoxazole were detected in groundwater, with concentrations reaching 67.1, 106.7, 506.7, and 113.8 ng L-1, respectively. Three of these compounds, carbamazepine-10,11-epoxide, carbamazepine diol, and N4-acetylsulfamethoxazole, were also present in soils with concentrations reaching 10.0, 353.5, and 59.1 ng g-1 dry weight, respectively, indicating potential soil-to-groundwater transfer. Principal component analysis revealed a strong correlation between the application of commercial inorganic fertilizers and carbamazepine-10,11-epoxide levels and the irrigation practices and the levels of caffeine, carbamazepine diol, and N4-acetylsulfamethoxazole in the soil and groundwater. Risk quotients showed that caffeine poses negligible risk to human health through drinking water exposure. Overall, the findings suggest that pharmaceuticals are present in South African croplands and underlying groundwater, though current levels do not pose a significant risk to human health. However, future studies should focus on other metabolites of pharmaceuticals due to their higher concentrations in the soil and groundwater.

Keywords: Cropland; Groundwater; Occurrence; Pharmaceuticals; Risk.

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Conflict of interest statement

Declarations. Ethics approval: All authors have read, understood, and have complied as applicable with the statement on “Ethical responsibilities of Authors” as found in the Instructions for Authors. Consent for publication: The results provided in this manuscript have not published elsewhere, nor are they under consideration by another publisher. Consent to participate: All authors have given consent to their contribution. Competing interests: The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
The map of South Africa (top right) showing the Gauteng province (left) and the location of the farms (yellow) where the study was conducted
Fig. 2
Fig. 2
Detection rates of target pharmaceuticals in representative cropland soils and their underlying groundwater in Gauteng province, South Africa. CAF means caffeine, CBZ means carbamazepine, CBZ-EP means carbamazepine-10,11-epoxide, CBZ-DiOH means carbamazepine diol, DCF means diclofenac, SMX means sulfamethoxazole, Ac-SMX means N4-acetylsulfamethoxazole, and SMX-N1-Glu means sulfamethoxazole-N1-glucuronide
Fig. 3
Fig. 3
Loading plot showing correlations between physicochemical parameters and pharmaceuticals content in the soil. CBZ-EP means carbamazepine-10,11-epoxide, CBZ-DiOH means carbamazepine diol, and Ac-SMX means N4-acetylsulfamethoxazole
Fig. 4
Fig. 4
Loading plot showing correlations between physicochemical parameters and pharmaceuticals content in groundwater. CAF means caffeine, CBZ-EP means carbamazepine-10,11-epoxide, CBZ-DiOH means carbamazepine diol, and Ac-SMX means N4-acetyl sulfamethoxazole
Fig. 5
Fig. 5
Bi-plot showing the correlation between the farm management practices and the occurrence of pharmaceuticals in the cropland soils in Gauteng province, South Africa. CBZ-EP means carbamazepine-10,11-epoxide, CBZ-DiOH means carbamazepine diol, and Ac-SMX means N4-acetyl sulfamethoxazole
Fig. 6
Fig. 6
Bi-plot showing the correlation between the farm management practices and the occurrence of pharmaceuticals in groundwater underlying representative cropland soils in Gauteng province, South Africa. CAF means caffeine, CBZ-EP means carbamazepine-10,11-epoxide, CBZ-DiOH means carbamazepine diol, and Ac-SMX means N4-acetyl sulfamethoxazole
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