Development of a coupled model of quantitative ion character-activity relationships-biotic ligand model (QICARs-BLM) for predicting toxicity for data poor metals

• Published in: Journal of hazardous materials Vol. 373; pp. 620 - 629
• Main Authors: Meng, Xiaoqi, Wang, Xuedong, Ma, Yibing, Wang, Ying
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 05.07.2019
• Subjects: Animals; Biotic ligand model (BLM); Conditional binding constants (K); Hordeum; Ions - chemistry; Ions - toxicity; Lactuca; Median effective concentration (EC50); Metals; Metals - chemistry; Metals - toxicity; Models, Biological; Oligochaeta; Quantitative ion character-activity relationships (QICARs); Soil Pollutants - chemistry; Soil Pollutants - toxicity; Toxicity Tests; PCs; BLM; Median effective concentration (EC50); Metals; BL; QICAR; RMSE; CCCs; PCA; Quantitative ion character-activity relationships (QICARs); CCR; Conditional binding constants (K); Biotic ligand model (BLM); Median effective concentration (EC)
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2019.03.094

[Display omitted] •Metal ionic characters-△IP and X, were associated with BLM parameter log K.•Three QICAR model were developed based on the relationship of △IP and X with log K for barley, earthworm, and lettuce.•The QICAR were coupled with the BLM and a novel QICAR-BLM was constructed.•The QICAR-BLM can be used to predict EC50 for unknown-toxicity metals. The biotic ligand model (BLM) is proposed as a tool to quantitatively evaluate biological toxicity of metals considering both metal speciation and the influence of environmental conditions. The model assumes that biological sites bind to metals as biotic ligands (BLs) and obtains a series of BLM parameters including conditional binding constants (K). However, developing a BLM for each metal and biology takes a lot of experimentation. In the present study, relationships between metal ionic characters and BLM parameter K were respectively investigated for three terrestrial organisms. The results showed that ionization potential was the most strongly related to log K for barley (R2 = 0.845, p <  0.01) and earthworm (R2 = 0.881, p <  0.01), and electronegativity index most significantly related to log K for lettuce (R2 = 0.835, p <  0.01). Based on these relationships, a set of quantitative ion character-activity relationships (QICARs) were developed for predicting log K of metals. Then the QICAR were coupled with BLM and a novel QICAR-BLM was constructed. Finally, the QICAR-BLM was applied to predict EC50 of other unknown-toxicity metals for selected species, and compensate for the lack of toxicity data for a large number of metals in soil.