Recently, relying on a key campus-supported platform for the Development of Characteristic Directions in Marine Disciplines, the “Marine Ecological Security and Sustainable Development” research team led by Prof. Jingjing Zhan of the School of Chemical Engineering, Ocean and Life Sciences has made important progress in the assessment of the ecological impact of herbicides on marine phytoplankton. The findings entitled “Herbicide Butafenacil and Its Transformation Products Significantly Influence Ecological Dynamics in Marine Environments” have been published in the renowned journal Environmental Science & Technology.

Herbicides are widely applied in modern agricultural production. Their residues can enter the ocean via surface runoff, thereby affecting the growth and community structure of phytoplankton, the marine primary producers. However, studies on the environmental behaviors and ecological consequences of such pollutants after they enter marine environments remain quite limited. To address this, the research team focused on butafenacil (BFA), a widely used protoporphyrinogen oxidase (PPO)-inhibiting herbicide, and carried out systematic research using microalgae. The results reveal that BFA exhibits extremely high toxicity to marine microalgae, and its transformation products (TPs) can continuously affect the community structure and ecological balance of marine microalgae.

This study reveals that BFA exerts toxic effects on the marine diatom Skeletonema costatum and the green alga Chlorella sp. at concentrations down to approximately 1 μg/L. BFA exposure can markedly strengthen the competitive advantage of Chlorella sp. and trigger the succession of dominant microalgal populations from other algal species to Chlorella sp. Using non-targeted analysis combining solid-phase extraction and liquid chromatography–high-resolution tandem mass spectrometry, the research team identified 16 BFA transformation products in BFA-impacted seawater, among which 13 were newly discovered. Through predictive computational toxicology, preparative liquid chromatography for separation and purification, and algal toxicity bioassays, the study verified that most TPs retain high biological toxicity, and some products (e.g., TP298) exhibit even higher toxicity than the parent molecule.

These findings challenge the conventional hypothesis that cleavage of the trifluoromethyl group of a pollutant leads to detoxification, elucidate the intrinsic cause of persistent ecotoxicity after degradation of the parent compound, and fully demonstrate the necessity of conducting ecological risk assessments for pollutant TPs.

This research was supported by the Fundamental Research Funds for the Central Universities and the National Natural Science Foundation of China.

Paper DOI：https://doi.org/10.1021/acs.est.6c10494