Food Chain Transfer Of Nano-TiO₂ In Aquatic Ecosystem

The recent widespread use of nanomaterial in people's daily life and industry production has led to increased concerns surrounding its health risks and environmental impact.Nanomaterials may release into the aquatic environment inevitably through multiple ways which would affect the aquatic ecosystem.Nanometer titanium dioxide?nano-TiO₂?is one of the most important nanometer-sized materials,and many research on biological safety of nanomaterials are reported,but most focused primarily on aqueous-phase exposures to single test organism and very little is known about the dietary intake of food-associated nanoparticles.Due to the small particle size and large surface area,nano-TiO₂ prone to reunite and subsidence,thus some surfactants such as sodium dodecyl benzene sulfonic?SDBS?often used to disperse and stabilize engineered nanoparticles.However,little is known about the effect of SDBS on the bioavailability of nano-TiO₂.Therefore,it is very important to study the transmission and accumulation of nano-TiO₂ along the multistage aquatic food chain and explore the influence of surfactants on nano-TiO₂ bioavailability for accurate assessment of environmental risks and ecological effect of nano-TiO₂.To accurately evaluate the environmental safety of nano-TiO₂,wedesigned different chain lengths of aquatic food chain to preliminarily explore the transmission and accumulation of nano-TiO₂ and surfactant SDBS along the secondary food chain?fairy shrimp-zebrafish?and three levelsof food chain?fairy shrimp-zebrafish-carp?.We determined the concentration of nano-TiO₂ in each trophic level organisms and their tissues distribution,we also observed the histopathology of top trophic level organisms.The study found that 100 mg/L nano-TiO₂ was optimally dispersed in aqueous solutions containing about 8 mg/L SDBS.Nano-TiO₂ can transfer and accumulate along the secondary food chain?fairy shrimp-zebrafish?and three levels of food chain?fairy shrimp-zebrafish-carp?.In the uptake period,the volume of nano-TiO₂ in fish was increased gradually with the extension of time;in the depuration period,the volume of nano-TiO₂ in fish was reduced,suggesting that fish itself has a certain self-purification and detoxification function.After the food chain transmission,nano-TiO₂ showed a certain tissue distribution in fish,and the Ti content in intestine is the highest,followed by heart,liver,gill,and brain is the lowest.It also found obvious tissues damage in fish.What is more,there were more tissues damaged when transferred along the three levels of food chain?fairy shrimp-zebrafish-carp?than the secondary food chain?fairy shrimp-zebrafish?.The addition of SDBS is not only increase the volume of nano-TiO₂ in organisms but also contributed to thebiological tissue damage.With the addition of SDBS,fish accumulated more nano-TiO₂ in its tissues and the tissues damage were more serious.