Studying the Influence of Soil Characteristics on Selenium Distribution in Bas-Chellif Soils Algeria and Predicting Speciation Patterns

Knowledge of the geochemistry of selenium (Se) is crucial for understanding its behavior in the environment. While numerous studies have explored selenium geochemistry, there is a notable inadequacy, especially in extreme soil conditions such as saline soils, which are widespread globally. This study focuses on characterizing the geochemistry of selenium in saline soils, with a specific focus on the El Hamadna perimeter in Bas-Cheliff, Algeria. This location was chosen due to its diverse salinity levels and selenium content. Utilizing Phreeqc software, the study examines selenium’s chemical speciation. In the arid soils of this region, predicted selenium (IV) concentrations range from 0.19 to 3.05 mg kg^–1, and selenium (VI) concentrations range from 0.54 to 5.58 mg kg^–1. A significant negative correlation was observed between total selenium and Se(VI) concentrations with pH, whereas Se(IV) showed a positive and significant correlation with pH. No correlation was found between selenium concentrations and the salinity gradient in the studied soils. Non-significant correlations were observed between selenium levels and CaCO₃, clay, and organic matter in the soils, suggesting that these soil properties do not influence the distribution of selenium concentrations in the examined soils. Only the pH and the presence of the main form MgSeO₃ control the representation of selenium in the soil profile.