Industrial settleable particulate matter promote metal(loid) bioaccumulation, metallic nanoparticle internalization and cardiac dysfunction in bullfrog tadpole

Industrial settleable particulate matter (SePM) represents a significant yet underrecognized source of metallic contaminants in freshwater environments. This study investigated the acute effects of metallurgy-derived SePM on bullfrog tadpoles ( Aquarana catesbeiana ), with emphasis on cardiac physiology, oxidative stress, and tissue metal(loid) accumulation. Short-term exposure led to marked increases in both classical (Fe, Ag, Ba) and emerging (Ce, Ti, V) metals within cardiac tissue, with electron microscopy confirming intracellular nanoparticles (Fe, Al, Sn, Ni) in cardiomyocytes. SePM exposure triggered elevated heart rates, enhanced contractile force, ventricular remodeling, and disrupted redox balance, evidenced by increased lipid peroxidation and protein carbonylation. These physiological alterations increase energy expenditure, potentially compromising growth and delaying developmental progression. Our findings demonstrate that SePM acts a vector for the cross-compartmental transfer of metallic contaminants and directly induces toxicity in amphibian larvae. These findings highlight the urgent need for more stringent regulation and comprehensive monitoring of metallic particulate emissions to better protect aquatic organisms and ecosystem integrity.