Individual and combined toxicities of fluorescent polystyrene nanoplastics and chromium(<scp>iii</scp>) nitrate nonahydrate in <i>Artemia salina</i>

There is a growing apprehension on the toxic effects of various pollutants on marine ecosystems. This study was aimed to investigate the influence of the combination of 200 nm fluorescent polystyrene nanoplastics (F-PSNPs) and chromium(III) nitrate nonahydrate (CNN) on their toxicity in <i>Artemia salina</i>, a marine crustacean. The interaction between CNN and F-PSNPs in natural seawater resulted in the formation of micron-sized particles. This interaction also caused a decrease in F-PSNP fluorophore intensity. Reduced residual CNN concentration within the mixture indicated CNN binding to F-PSNPs. Acute toxicity tests were conducted on <i>Artemia salina</i> using different concentrations of F-PSNPs alone, CNN alone, and the F-PSNPs + CNN complex. The study assessed the potential toxicity of these emerging contaminants by examining the mortality rates, hatching success, morphological changes, and biochemical alterations in <i>Artemia salina</i>. Exposure to the F-PSNPs + CNN complex resulted in a decreased hatching success, an increased mortality rate, elevated levels of reactive oxygen species, catalase, lipid peroxidase, and superoxide dismutase, and reduced total protein content, and the independent action model suggested an additive toxic effect of the complex. Significant differences were noted between the impact of the complex and the individual. However, the accumulation of these particles in organisms may affect the food chain. These findings underscore the potential environmental risks associated with the concurrent exposure of aquatic organisms to nanoplastics and other co-contaminating heavy metals.