A Structured Review of Selenium Pollution in Global Aquatic Environments: Sources, Levels, and Co‐Pollutants

ABSTRACT Despite its nutritional and industrial significance, selenium (Se) is considered a pollutant in aquatic environments owing to its toxicity at elevated concentrations, which potentially cause environmental degradation and adverse health effects in humans and local biota. We conducted a structured review of studies published between 2015 and 2024 to identify Se sources, contamination levels, and co‐occurring inorganic pollutants in surface water and groundwater impacted with Se pollution. We found that anthropogenic activities, particularly mining, are the predominant sources of Se pollution, accounting for over 71% of all cases. Industrial and agricultural activities also contribute to a lesser extent. Geogenic processes, including mineral oxidation, weathering, and seawater intrusion, also cause excessive Se accumulation predominantly in groundwater. In most freshwater sources, Se concentrations range from 100 to 1000 µg/L ( n = 59 of 116 water bodies); however, values from anthropogenic sources can be significantly higher, reaching up to 7640 µg/L. Se pollution is frequently associated with several co‐pollutants across all sources, including anions such as chloride and phosphate, as well as metals such as cadmium, lead, and nickel, but arsenic is consistently the most prevalent, with concentrations generally ranging between 10 and 100 µg/L. Other significant co‐pollutants, including aluminum, chromium, mercury, manganese, uranium, vanadium, and antimony, are source‐specific. This structured review provides essential insights for addressing sources and concentration ranges of Se pollution and highlights the necessity for developing simultaneous removal strategies of Se and its co‐pollutants from global aquatic environments and groundwater sources.