From source to sink: A review of aluminum fate in groundwater and potential risks

Groundwater aluminum contamination has increasingly attracted attention in groundwater research and management due to its complex geochemical behavior and potential ecological risks.Aluminum is the most abundant metallic element in the Earth’s crust and serves as a critical raw material for the metal industries. However, the massive leakage of high-aluminum and acidic wastewater during the production and processing processes has led to changes in groundwater pH and an increase in aluminum concentration. We analyzed the global distribution and characteristics of aluminum-contaminated sites and systematically discussed the sources, hydrogeochemical processes, as well as toxicity and health risks of aluminum contamination. The major findings of this study are summarized as follows. Based on our literature collection, there are a total of 204 aluminum-contaminated sites worldwide, where pH acts as a key controlling factor governing aluminum mobility and distribution. The most frequently observed aluminum concentrations at contaminated sites range from 1 to 10 mg/L. From the source perspective, aluminum contamination originates from both geogenic and anthropogenic inputs. Geogenic processes are primarily driven by rock weathering, whereas anthropogenic sources include acid mine drainage, industrial and domestic wastewater discharge, and agricultural activities. These anthropogenic inputs mobilize aluminum along surface–subsurface transport pathways, where dissolved and colloidal species migrate through vadose zones into aquifers, ultimately accumulating in groundwater discharge zones such as rivers, wetlands, and coastal aquifers. Our geochemical simulations indicate that aluminum exhibits enhanced solubility and mobility under conditions of high fluoride, high sulfate, and elevated salinity.Aluminum pollution imposes substantial stress on plants, aquatic organisms, and microorganisms. Excessive aluminum intake also poses potential health risks to humans, particularly affecting the nervous, respiratory, and reproductive systems. Addressing this challenge requires prioritizing source control in mining and industrial sectors, implementing real-time aluminum speciation monitoring in high-risk aquifers, and establishing region-specific regulatory thresholds that account for local hydrogeochemical conditions rather than adopting uniform concentration limits.