Dissolved Organic Matter Mitigates the Acute Toxicity of Thulium to Hyalella azteca but Ca, Mg and Na Do Not.

The demand for rare earth elements (REEs) is growing and as a result, environmental exposure is a concern. The objective of this research was to evaluate the acute toxicity of Tm to Hyalella azteca and to understand the potential for toxicity modification by dissolved organic matter (DOM) and the cations Ca, Mg and Na. Standard methods were followed for 96 h static exposures in a medium with a hardness of 60 mg CaCO/L, pH of 7.