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.