Nanoscale zero-valent iron alters physiological, biochemical, and transcriptomic response of nonylphenol-exposed...

Nanoparticles and organic pollutants are two major contaminants found in aquatic environments. Algae are regarded as the model organism for the risk assessment of pollutants in water. In our previous study, we investigated the toxic effects of nonylphenol (NP), a typical organic water pollutant, on algae; however, it remains unclear how algae respond to the coexistence of NP and nanoparticles. In this study, a concentration gradient of nanoscale zero-valent iron (nZVI; 10, 50, 100, and 200 mg/L) was added to NP-exposed Dictyosphaerium sp. to investigate both the toxic effects of this combination and the potential for NP removal. nZVI had a dose-dependent effect on NP-exposed algae, with high nZVI concentrations significantly decreasing algal biomass and pigment content, as well as severely damaging algal cellular ultrastructure. In addition, genes involved in antioxidant response, photosynthesis, and ribosome synthesis were significantly altered when NP-exposed algae were incubated with nZVI. In contrast to high nZVI concentrations, adding a small concentration of nZVI led to reduced toxicity in NP-exposed algae, while significantly enhancing the NP removal rate. This study improves our understanding of algal responses to various pollutants and suggests that nZVI may assist in the remediation of NP in aquatic ecosystems.