Calculation of Toxicity Coefficient of Potential Ecological Risk Assessment of Rare Earth Elements.

Rare earth elements (REEs) are applied in various industries. They have entered the environment through different pathways and caused serious pollutions. So far, due to the lack of calculated toxicity coefficient of rare earth elements, it is still difficult to evaluate their ecological risks. The potential ecological risk index method is commonly used in the pollution assessment of heavy metals. And rare earth elements are similar to heavy metals. Herein, we used this method to calculate the toxicity coefficient of 15 rare earth elements (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y). The calculation was based on two principles, rare earth elements coexist with each other because of their similar chemical properties, and the elemental abundance and release effect determine their toxicity. The results are as follows: La = 1, Ce = 1, Pr = 5, Nd = 2, Sm = 5, Eu = 10, Gd = 5, Tb = 10, Dy = 5, Ho = 10, Er = 5, Tm = 10, Yb = 5, Lu = 20, Y = 2. Our results can provide a reference to the potential ecological risk assessment of rare earth elements.