(Non-)leaking of electric scooter batteries dumped for more than a year in a freshwater pond.

Background: Electric scooters become popular in Western cities as new mobility option. Start-up companies rent out e-scooters in major cities, such as Paris, Cologne, Copenhagen and elsewhere. However, the scooters are frequently vandalized and thrown into surface waters. There is concern about a new kind of water pollution from leaking scooter batteries.

Methods: Two scooter batteries (lithium ion type) were dumped into artificial 200 L ponds for over a year. Concentrations of Li, Mn, Co, Ni and Cu in the pond water were several times analyzed by ICP-MS over a period of 16 months.

Results: In ponds with dumped batteries, copper levels in water were elevated (8.9 to 40.6 μg/L versus ≤0.6 μg/L in controls), as well as nickel levels (4.8 to 7.2 μg/L versus ≤0.6 μg/L in controls), while lithium concentrations were only slightly higher (7.1 to 9.6 μg/L versus 6.4 to 6.7 μg/L in controls), as were levels of Co (<1 μg/L, except one sample). Manganese was lower in ponds with battery than in controls.

Conclusions: Less than 1‰ of the toxic metals Ni, Co and Cu stored in the battery pack was recovered from the test ponds, and these amounts can be explained by corrosion of the connections and of the steel encapsulation of the batteries. No elevated levels of Mn were observed in the test ponds. We conclude that the batteries are well sealed against leaking, and dilution in natural water bodies will minimize the hazard to aquatic organisms. Nonetheless, rapid removal of batteries dumped by vandals into rivers and lakes from the surface waters is advised because no sealing can hold forever.