Dietary Bioavailability of Uranium to a Model Freshwater Invertebrate

Area of Science:

• Environmental Science
• Ecotoxicology
• Geochemistry

Background:

• Uranium mining poses environmental exposure risks.
• Understanding uranium uptake in organisms is key for assessing bioaccumulation and toxicity.
• Uranium bioavailability is well-studied in dissolved exposures but less understood in dietary exposures.

Purpose of the Study:

• To characterize the biogeochemical drivers of dietary uranium uptake in the freshwater snail *Lymnaea stagnalis*.
• To evaluate uranium bioavailability from various solid matrices.
• To assess the impact of dietary uranium on snail feeding behavior.

Main Methods:

• Laboratory experiments using *Lymnaea stagnalis*.
• Testing uranium bioavailability from pre-exposed diatoms, contaminated soils, and hydrous ferric oxide (HFO) with and without natural organic matter (NOM).
• Measuring uranium assimilation efficiency (AE) and feeding rates.

Main Results:

• Uranium was bioavailable from all tested solids.
• Uranium AE varied significantly, being lowest from soils (25 ± 17%) and highest from diatoms (71 ± 13%).
• Dietary uranium exposure reduced feeding rates, with inhibition inversely related to uranium bioavailability.

Conclusions:

• Dietary uranium uptake in *Lymnaea stagnalis* is influenced by the geochemical properties of the exposure source.
• The high variability in uranium assimilation efficiency has implications for toxicity assessments.
• Considering dietary uptake is essential for accurate environmental risk evaluation of uranium contamination.