Toxicity identification evaluation of riverine water using seed germination: lead toxicity in the Fen River’s Taiyuan section of China

A phytotoxicity-based toxicity identification evaluation (TIE) approach was employed to identify toxic substances in river water, focusing on the Taiyuan section of the Fen River in China as a case study. Four vegetable seed species—amaranth, oilseed rape, cabbage, and lettuce—were selected for toxicity screening. An analysis of variance was performed on the germination index (GI%) of these seeds exposed to nine initial water samples from the Fen River. This analysis revealed that the sampling site with the lowest GI% was S6. Consequently, samples from the S6 site were used for subsequent TIE treatments, which included aeration, EDTA chelation, reduction with oxidizing agents, filtration, solid-phase extraction using C18, and pH adjustment. As a result, EDTA and its related treatment significantly improved seed viability across nearly all species, underscoring the role of cationic metals in contributing to toxicity. Correspondingly, 10 metals in the initial water samples were analyzed using inductively coupled plasma mass spectrometry. Linear correlations were observed between the concentrations of metals (cobalt, chromium, nickel, and lead) and the phytotoxicity observed in the four vegetable species, with correlation coefficients exceeding 0.5 ( p < 0.01). Finally, Canonical correlation analysis suggested that exposure to lead in riverine water was most likely associated with the phytotoxic effects observed in oilseed rape and cabbage, contributing to overall toxicity. In conclusion, lead was confirmed as the primary toxicant responsible for the observed phytotoxic effects in oilseed rape and cabbage in the Fen River. Although metal concentrations remained below the Environmental Quality Standards for Surface Water thresholds, the identified ecological risks underscore the need for enhanced monitoring and management. The phytotoxicity-based TIE approach proved effective in identifying specific toxicants, providing valuable insights for water quality management and ecological risk assessment.