Objective Antimony (Sb) is utilized as a catalyst during the polymerization process of polyethylene terephthalate (PET) and it remains in PET fibers or textiles. When printing and dyeing PET, Sb will leach into wastewater and cause contamination, and it commonly exists in aquatic environments in two oxidation states: + 3 and +5. Investigating their toxicological effects on aquatic ecosystems is highly necessary. Microalgae are the primary producers in aquatic ecosystems, and their short growth cycle and ease of isolation make them highly suitable for studying the toxic effects of Sb pollutants on aquatic ecosystems. Method Representatives of green algae, Raphidocelis subcapitata and Chlamydomonas reinhardtii, and representatives of cyanobacteria, Synechococcus and Dolichospermum sp., were selected for investigation. The growth status of the microalgae was evaluated by measuring algal cell concentration, chlorophyll a, and soluble protein. The potential oxidative stress caused by exposure to Sb (III) and Sb (V) was assessed by measuring the activities of superoxide dismutase (SOD) and catalase (CAT). The potential damage to microalgal was determined through subcellular structure observation by TEM. Additionally, the adsorption or absorption of Sb (III ) and Sb(V) by microalgae were quantified to determine the extent of adsorption relative to their growth status. Results The results revealed that under different concentrations of Sb (III) and Sb (V) stress for 72 h, Hormesis effect was observed in four algae species, i. e. Raphidocelis subcapitata, Chlamydomonas reinhardtii, Synechococcus, Dolichospermum sp. Sb(III) had a more potent inhibitory effect on microalgae, with up to a 76. 6% reduction in growth, compared to Sb(V) which only resulted in a 41. 0% decrease. Green algae were found to be more vulnerable to Sb-induced stress compared to cyanobacteria. The toxic impact of Sb on microalgae was primarily attributed to the impairment of their photosynthetic machinery and the occurrence of oxidative damage. Alterations in the synthesis of chlorophyll a and soluble protein content in microalgae indicated similar trends in response to growth inhibition, but the impact on cyanobacteria was less pronounced. Additionally, the activities of SOD and CAT in green algae exhibited a pattern of promotion at low concentrations and inhibition at high concentrations, while cyanobacteria showed a variable pattern of changes. Subcellular examination of microalgae revealed that Chlamydomonas reinhardtii experienced damage to the cell wall, nucleus, chloroplasts, and other organelles, whereas Synechococcus suffered damage mainly to the photosynthetic system. Further, all four microalgae had greater sorption and uptake of Sb (III) than Sb (V), but there was no clear correlation between the uptake or sorption of antimony by microalgae and their tolerance to antimony stress. Conclusion Antimony contamination has become an increasing concern, and it is essential to comprehend the toxicity and toxic mechanisms of Sb of different valence. This study found that the toxicity of Sb (III) to microalgae is significantly higher than that of Sb(V), and that green algae are more sensitive to Sb stress than blue algae. When the exposure concentration of Sb(III) is below 0. 05 mg/L and the exposure concentration of Sb(V) is below 0.2 mg/L, the toxicity impact on microalgae is relatively small. The mechanisms by which Sb affects microalgae are primarily associated with harm to the photosynthetic system and oxidative stress. Under Sb (EI) stress, the cell wall, nucleus, chloroplasts, and other organelles of green algae are damaged, while in blue-green algae, the photosynthetic system is primarily affected. The above research results are expected to provide certain basis for a comprehensive assessment of the ecological risks of Sb pollutants. © 2024 China Textile Engineering Society. All rights reserved.
