The developmental toxicity, bioaccumulation and distribution of oxidized single walled carbon nanotubes in Artemia salina

With the increasing production and applications of single walled carbon nanotubes (SWCNTs), concerns about the likelihood of SWCNTs being present in the aquatic environment and the subsequent effects on aquatic organisms are emerging. This work aimed to investigate the developmental toxicity, bioaccumulation and distribution of oxidized SWCNTs (O-SWCNTs) in a marine model organism, Artemia salina (A. salina). The results indicated that the hatching rates of capsulated and decapsulated cysts were decreased as the O-SWCNT concentration increased from 0 to 600 mg L-1 at 12, 18, 24 and 36 h. For instar I, II and III larvae exposure to 600 mg L-1, the mean mortality rates were 36.1%, 57.9% and 45.2%, respectively. Both the body length and swimming speed showed a concentration-dependent decrease after exposure to O-SWCNTs for 24 h. The inhibition of swimming may be caused by (1) the malformation of gills; (2) the attachment of O-SWCNTs on the gills. Reactive oxygen species (ROS) and antioxidant enzyme (catalase, superoxide dismutase and glutathione peroxidase) activities substantially increased following exposure, indicating that the toxic effects were related to oxidative stress. O-SWCNTs can be ingested, accumulated and excreted by A. salina, and distributed in the intestine, lipid vesicles and phagocytes. However, the accumulated O-SWCNTs were not completely excreted by A. salina. Uptake kinetics data showed that the O-SWCNT content increased from 1 to 48 h followed by a decrease from 48 to 72 h in the range from 0.08 to 5.7 mg g(-1). The combined results so far indicate that O-SWCNTs have the potential to affect aquatic organisms when released into the marine ecosystems.