Environmental Fate and Toxicity of Zinc Oxide Nanoparticles in Aquatic Ecosystems: A Comprehensive Review

Abstract

Zinc oxide nanoparticles (ZnO NPs) are increasingly utilized in agriculture, electronics, and medicine, raising concerns about their environmental fate and toxicity in aquatic ecosystems. This study aims to review the fate, bioaccumulation, and toxicity of ZnO NPs in aquatic ecosystem. This review was conducted through a comprehensive analysis of peer-reviewed literature from databases such as Scopus, Web of Science, and PubMed. Finding indicates that ZnO NP fate in aquatic ecosystems is governed by key environmental factors, including pH, ionic strength, and DOM. ZnO NPs tend to aggregate in high-salinity environments, whereas acidic conditions enhance dissolution, leading to increased Zn²⁺ ion release and potential toxicity. Smaller ZnO NPs exhibit higher reactivity and bioavailability, increasing their potential for bioaccumulation. Bioaccumulation of ZnO NPs is influenced by concentration, exposure time, and particle size, with smaller nanoparticles being more readily absorbed by aquatic organisms. Toxicity varies depending on exposure duration and environmental conditions, with DOM playing a mitigating role by reducing Zn²⁺ ion availability. Additionally, ZnO NP exposure has been linked to oxidative stress, developmental abnormalities, and behavioral changes in aquatic organisms, highlighting the need for regulations and tailored risk assessments that account for water chemistry variations to mitigate ecological risks. Future research should focus on long-term impacts, including multi-species interactions and trophic transfer, to improve mitigation strategies