Study of environmental risks incurred by leakage of lithium cells to the food chain in a freshwater ecosystem

Water flea (Daphnia magna) and fish (Carassius auratus) at trophic level were used for comprehensive evaluation of environmental risks incurred by manufactured nanomaterial (nNi(OH)₂) as leaked from lithium cells to the food chain in freshwater ecosystem. The 48, 72 and 96 h acute toxicities of water suspensions of nNi(OH)₂ to the flea and the fish were tested, using the immobilization and the mortality as toxicological endpoints. The results showed that the water flea was more highly sensitive to nNi(OH)₂ than the fish. Then, the fish were exposed to 1.0 mg/L nNi(OH)₂ for 6, 12, 24, 36, 48, 60, 72 and 96 h, and the relationship between the concentrations in the water and the fish were described by a bioconcentration factor (BCF). After calculation, lgBCF is 1.61. Reactive oxygen species (ROS) generation was studied after fish were exposed to 1.0 mg/L water suspensions of nNi(OH)₂ for 24 h. As proved by electron paramagnetic resonance, nNi(OH)₂ may induce the generation of hydroxyl radical in the fish, and nNi(OH)₂ as concentrated in the fish may incur redox reaction and produce redox metabolic intermediates. As one of the important toxic mechanisms of nNi(OH)₂ to the fish, the oxidative stress mechanism requires further study.