Using principal component analysis to distinguish sources of radioactivity and nitrates contamination in Southern Tunisian groundwater samples

The manuscript discusses using Principal Component Analysis (PCA) to distinguish the sources of radioactive and nitrate contamination in 33 groundwater samples from southern Tunisia. The study focuses on the Gafsa basin, an area known for its phosphate mining activities and significant agricultural use, both of which contribute to the contamination of groundwater resources. The radioactivity in the water is primarily attributed to phosphate mining and deep groundwater sources from the North Western Sahara Aquifer System (NWSAS). Additionally, the nitrate contamination is largely due to agricultural runoff, though secondary sources related to phosphate mining are also considered. Through the application of PCA, the study was able to classify the groundwater samples into different groups based on their contamination sources: phosphate mining, combined agricultural and mining activities, fossil geothermal waters, and low-agricultural areas. The PCA revealed that samples most affected by anthropogenic activities exhibited high levels of radium and nitrate, with contamination patterns correlating with specific environmental and chemical factors. This analysis underscores the complexity of groundwater contamination in the region and highlights the need for targeted mitigation strategies to address radioactive and nitrate pollution in southern Tunisia. The study provides critical insights for managing water quality in areas with similar environmental challenges.