Toxicological effects of different ionic liquids on growth, photosynthetic pigments, oxidative stress, and ultrastructure of Nostoc punctiforme and the combined toxicity with heavy metals

• Published in: Chemosphere (Oxford) 2022-07, Vol.298, p.134273-134273, Article 134273
• Main Authors: Chu, Linglong, Hou, Xiaoxiao, Song, Xinshan, Zhao, Xiaoxiang
• Format: Article
• Language: English
• Subjects: Anion; Heavy metals; Ionic liquids; Methyl substitution; Nostoc punctiforme
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2022.134273

Ionic liquids (ILs1) are used widely because of their excellent properties. However, their ecotoxicity for environment has aroused great concern. Here we studied, the toxicity of three ILs with different numbers of methyl substituents and anions as well as the combined effect of heavy metals to edible algae Nostoc punctiforme. The results show that fresh weight and chlorophyll content decreased, indicating that the growth and photosynthesis were adversely affected. Polysaccharides and soluble protein contents decreased, resulting in a reduced nutritional value of Nostoc punctiforme. ILs can produce many reactive oxygen species (ROS), which lead to increased the malondialdehyde (MDA) content. In order to remove excessive ROS, antioxidant enzymes activity is increased, but decreases under high IL concentration, because the structure and function of the enzymes became damaged. ILs cause stress to algae, as the cell ultrastructure is indicating by increased amounts of starch and osmiophilic globules. The combined action of heavy metals with ILs decreases the antioxidant enzymes activity and chlorophyll content, and increases the MDA content. The results show that the order of toxicity is [C8MIM]Cl >[C8MIM]Br> [C8DMIM]Br. The combination of heavy metals and ILs cause an increase of the toxicity to Nostoc punctiforme. [Display omitted] •The ionic liquids enter the edible algae cells and destroy their structure.•Ionic liquids reduce the nutrient composition and edible value of edible algae.•Ionic liquids disturbed the balance between ROS generation and degradation.•Ionic liquids and heavy metals have similar toxic effects on algal cells.•The toxicity to Nostoc punctiforme was enhanced after the combined action.