Uranflöden

Uranflöden refers to the flux of uranium as it moves between different environmental reservoirs, such as rocks, soils, groundwater, surface water and biota. The concept is used in geochemistry, hydrogeology and environmental science to describe how uranium enters and leaves systems over time, and how its distribution is controlled by natural processes and human activities.

Natural mobility of uranium depends strongly on its chemical form. In oxidizing conditions, uranium mainly exists as the uranyl ion UO22+ and forms soluble complexes with carbonate, sulfate or phosphate, which enhances its transport in water. Under reducing conditions, uranium tends to be immobilized as insoluble U(IV) minerals, limiting mobility. Geochemical interactions with minerals, especially iron and manganese oxides, clay minerals, organic matter and pH, further influence adsorption, desorption and precipitation, shaping uranium fluxes in soils and aquifers.

In groundwater, uranium plumes can develop from weathering of uranium-bearing rocks or from mining-related activities. Rivers and lakes transport dissolved uranium and particulates, contributing to downstream accumulation in sediments. Anthropogenic uranium sources include mining and milling waste, phosphogypsum, nuclear fuel cycle activities and legacy contamination, which can create localized increases in fluxes and concentrations.

Measurement and assessment typically express uranium flow as mass per area per time (flux) or as concentration combined with water flux. Monitoring aims to protect water quality and assess risks to ecosystems and human health, given uranium’s chemical toxicity and radioactivity. Modeling of uranium fluxes integrates hydrology, geochemistry and environmental variability to predict movements and outcomes under different scenarios.