Ecological risk threshold for chromium in Chinese soils and its prediction models

• Published in: Environmental research 2024-12, Vol.262 (Pt 2), p.119935, Article 119935
• Main Authors: Sun, Xiaoyi, Qin, Luyao, Yu, Lei, Wang, Jing, Liu, Jiaxiao, Wang, Meng, Chen, Shibao
• Format: Article
• Language: English
• Subjects: Animals; China; Chromium; Chromium - analysis; Chromium - toxicity; Environmental Monitoring - methods; HC5; Hormesis; Risk Assessment; Soil - chemistry; Soil Microbiology; Soil Pollutants - analysis; Soil Pollutants - toxicity; SSD; Toxicity threshold
• ISSN: 0013-9351; 1096-0953; 1096-0953
• DOI: 10.1016/j.envres.2024.119935

The derivation of chromium (Cr) ecological risk thresholds in soils remains limited, despite their importance as measurement standards and indicators for enacting soil protection policies. In this study, toxicity of Cr in soil to different species was tested based on Log-Logistic dose-effect relationship. On this basis, combined with Cr toxicity measurement data in literature, the ecological risk threshold HC5 for protecting 95% species safety in soils with different properties was obtained by fitting species sensitivity distribution curve (SSD). This research collected various Cr toxicological data from Chinese cropland soils, based on 31 different endpoints covering soil fauna, functional indicators of microorganisms, terrestrial plants, etc., sourced from both our laboratory and existing literature. We applied the SSD method to estimate the hazardous concentration of Cr for HC5 and ultimately established a predictive model according to HC5 and different soil properties. As a result, the EC10 (an effective concentration of Cr resulting in 10% suppression of terminal biological activity) based on 7 different soils and 4 endpoints ranged from 16.8 to 148.0 mg kg−1, and the hormesis of Cr induction reached up to 109%. Overall, the toxicity (EC10) to microorganisms was much lower, while it was higher for graminoids. All the toxicity data were corrected through an aging factor with up to 540 days of equilibration before fitting the SSD curves. After that, a prediction model considering HC5 values and soil properties was established as LogHC5 = 3.003LogpH +0.651LogOC +0.013LogCEC - 0.476. The model was well-verified in field experiments, as the actual and predicted values fell within a 2-fold error range. This approach offers a rigorous scientific foundation for determining the Cr ecological risk threshold and could be important for the conservation of ecological species in soils. [Display omitted] •Hormesis was found in the responses of different species to low Cr toxicity in soils.•The EC10 for Cr toxicity to 31 species varied significantly, ranging from 5.63 to 245.13 mg kg−1.•HC5 of Cr varied from 53.8 to 245.0 mg kg−1 for different soils.•The prediction model of HC5 for Cr in soils was described as: LogHC5 = 3.003LogpH+0.651LogOC+0.013LogCEC-0.476.