Perfluorooctane sulfonate (PFOS) contamination poses a significant environmental threat due to its widespread distribution and persistence. However, the hepatotoxic effects of PFOS on key aquatic species, such as crucian carp, remain understudied. This study systematically investigated the hepatotoxicity and underlying molecular mechanisms associated with PFOS exposure in crucian carp over a 21 day period. We determined a 96 h 50% lethal concentration (LC₅₀) of 23.17 mg/L. Histopathological and transcriptomic analyses confirmed PFOS-induced liver damage in the carp, characterized by venous congestion, nucleolar dissolution and cellular vacuolation. Transcriptomic profiling further identified 1036 differentially expressed genes (DEGs), involving critical pathways related to lipid and energy metabolism, immunity, and endocrine regulation. These pathways are integral to the development of nonalcoholic fatty liver disease (NAFLD). Specifically, DEGs related to lipid metabolism showed significant changes, while those involved in energy metabolism indicated disrupted ATP production and mitochondrial function. Genes associated with immune response revealed an upregulation of pro-inflammatory markers, and hormone regulation genes highlighted alterations in endocrine signaling. Our findings emphasized that PFOS exhibits acute toxicity to crucian carp, potentially inducing hepatotoxicity by disrupting multiple physiological systems. This research provides a theoretical foundation for mitigating aquatic pollution and protecting eco-health, contributing to broader ecological and conservation biology discussions.

Engineered nanomaterials are widely used in environmental remediation, agriculture, and industrial applications owing to their large specific surface area, high reactivity, and tunable physicochemical properties. However, their release into aquatic environments has raised increasing concerns regarding potential risks to primary producers. Microalgae are highly sensitive to environmental stressors and play essential roles in photosynthesis, nutrient cycling, carbon fixation, and aquatic food-web stability, making them important model organisms for assessing the toxicity of engineered nanomaterials. This review summarizes the toxic effects and mechanisms of representative engineered nanomaterials, including metal and metal oxide nanoparticles, nanoplastics, and carbon-based nanomaterials, on microalgae. Major toxic pathways include nanoparticle attachment and aggregation on algal surfaces, shading effects, membrane damage, altered permeability, cellular internalization, toxic ion release, reactive oxygen species overproduction, photosynthetic inhibition, and metabolic disturbance. The review further discusses how particle size, morphology, surface coating, dissolution, aging, light, pH, and natural organic matter regulate nanomaterial bioavailability and toxicity. Combined toxicity caused by coexisting nanoparticles or emerging pollutants is also considered, with emphasis on synergistic, antagonistic, and concentration-dependent effects. Finally, recent methodological advances, such as near-native imaging, Raman-based spectroscopy, particle-specific elemental analysis, and multi-omics approaches, are highlighted. This review provides an integrated perspective for understanding nanomaterial toxicity to microalgae and supports future ecological risk assessment in aquatic environments.

Microplastic–heavy metal (MP-HM) complexes markedly modify HM migration, transformation and bioavailability in the environment, threatening ecosystem stability and public health. Many studies have examined the interfacial adsorption and toxicity of single-factor MP-HM contamination, yet existing reviews mostly rely on phenomenological descriptions, lacking systematic synthesis and critical discussion of core mechanisms, model constraints and field-scale evolutionary discrepancies. The long-term stability, interfacial reconstruction, and interconversion between free and MP-bound HMs under in situ dynamic conditions remain poorly understood. To fill this gap, this review clarifies divergent adsorption mechanisms governed by MP polymer properties and HM speciation, and identifies the fundamental limitations of conventional static models for dynamic environmental systems. We further analyze decoupling mechanisms underlying synergistic/antagonistic multi-factor interactions in complex matrices and explain inconsistencies across experimental observations. Accordingly, priority research directions are proposed, including in situ dynamic monitoring, coupled model refinement, and speciation-dependent risk assessment. This review provides new insights into the interfacial evolution of MP-HM co-contamination and supports targeted environmental risk mitigation strategies.