Effects Of Aqueous Stable Fullerene Nanocrystals (nC₆O) On Daphnia Magna: Evaluations Of Sublethal And Heavy Mentals Synergistic Toxicity

Concerns exist regarding the inadvertent release into natural systems after the widely applications of engineered nanomaterials, and the possible negative ecosystem responses that may occur. Understanding sublethal effects may be particularly important to determine ecosystem responses as current levels of nanomaterial are accumulating higher and higher. nC60 was selected as a nanomaterial objective, and Daphnia magna (D. magna) was selected as a tool to research on sublethal reproductive toxicities, on bioaccumulations on different factors and a mode for bioaccumulation; on joint toxicities included both Cd and Cu.After washed by ultra purified water for removing and alleviating toxic of THF and THF derivatives from nC60 suspension, effects of nC60 on D. magna were studied about the sublethal toxicity in reproductive cycle, bioaccumulation, and synergistic toxicity. Main results of this research were followed.nC60 caused sublethal reproductive toxicity in D. magnaAccording to the EPA 2024, nC60 LC50 = 0.44 mg L-1. Under different temperatures, sublethal toxicity of D. magna showed the similar trend, nC60 stressed the reproductive cycle: aborted the embryos, inhibited the maturation of newborns, and destroyed the reproduction of mother daphnids. In the reproductive phases, bioaccumulation showed in eggs, embryos, offspring, , and mother daphnids, and differential bioaccumulations occurred as a function of total lipid content in the daphnia. Sublethal toxicity and bioaccumulation of nC60 in daphnids tissues attached importance to the nanomaterial sublethal reproductive toxicity, showed the necessary of studying on nC60 and other nanomaterials under sublethal concentration.Different factors adjusted the bioaccumulationsDifferent environmental factors (hardness, pH, concentration and temperature) and physical property of nC60 adjusted the bioaccumulation of C60 in D. magna. Uptake amounts and rates into daphnids increased with time in all the experiments. Uptakes of nC60 increased with increasing concentration and particle size, and uptakes of particles more than 100 nm reached their maximums more quickly than those of less than 100 nm. Under the higher hardness, and with lower pH and higher temperature aqueous system, uptakes were more quickly and uptake amounts were lower than those under opposite related conditions. Uptakes in all batch tests reached the balance within 5 d. Both the properties of nC60 and environmental factors influenced the uptakes of nC60 by D. magna in aqueous system, and environmental factors may affect the accumulation by changing the property of nC60 and D. magna itself, which were critical to understand accumulations of fullerenes in aqueous system. And the bioaccumulation data fitted the exponential equation that growing to the maximum. It will show the good to the bioaccumulation and disposal of nC60 materials.nC60 enhanced the toxicity of CdNOECs of nC60 and Cd were confirmed by EPA 2024. Under the 48 h NOECs of both, nC60 enhanced the toxicity by 35% mortality of neonates, and ratio of both concentrations in this experiment was 1: 0.5. Adsorption of Cd onto nC60 particles was believed in enhancement of Cd accumulation, and desorption of Cd from nC60 in acidic condition in intestine was considered for enhancement of toxicity. Quickly desorption would increase the bio-available of Cd ions in intestine of D. magna, then overpass the threshold of toleration and cause the mortality after being absorbed by the intestine. In total, nC60 enhanced the toxicity and bioaccumulation of Cd in aqueous systems.nC60 enhanced the toxicity of CuD. magna was exposed to the mixture of copper solution and nC60 suspension, 100% mortality occurred at about half time, of which they were exposed to copper solution individually at the same concentration. The equilibrium of copper concentration in D. magma in the mixture of nC60 and copper solution was more than twice of that in copper solution only. Bioaccumulations of copper and C60 were increasing with the time and reached the equilibrium in 3 h, the former accumulated accompanying with the latter. Copper was quickly adsorbed onto nC60 nanoparticles and desorbed from nC60 in acidic condition. Copper ions desorbed will be taken up by the intestine, increased the bioavailable concentration of copper, overpassed the threshold, and caused higher toxicity than that of copper individual.