Ecological safety thresholds for phenanthrene in Chinese soils: implications for assessing ecological risks to vegetation and for land use

Phenanthrene poses carcinogenic, teratogenic and mutagenic risks to plants and soil invertebrates. However, the absence of established soil ecological safety thresholds of phenanthrene has resulted in insufficient evidence in the current risk assessment for soil ecological security. To fill this gap, toxicity data from laboratory experiments and the existing literature, covering 16 plant species, 7 invertebrates, and 3 soil ecological processes, were applied to the species sensitivity distribution approach to determine the soil ecological safety thresholds of phenanthrene across different land types. From experimental results, we found that the effect concentration at 10% values for most plants had a positive correlation with pH, soil organic matter content, cation exchange capacity, and electrical conductivity values. The soil ecological safety thresholds of phenanthrene were estimated to be 7 mg kg^-1 for agricultural and forestry land with the hazardous concentration for 5% of the species affected (HC₅), 35 mg kg^-1 for green spaces and squares with HC₂₀, 95 mg kg^-1 for residential land with HC₄₀, and 122 mg kg^-1 for commercial and industrial land with HC₅₀, respectively. These findings will serve as a foundation for the ecological risk assessment of phenanthrene on land for different purposes, and are of great significance for ecological species protection.