Press or pulse exposures determine the environmental fate of cerium nanoparticles in stream mesocosms.

摘要: Risk-assessment models indicate that stream ecosystems receiving municipal wastewater effluent may have the greatest potential for exposure to manufactured nanoparticles. The authors determined fate of cerium oxide (CeO2 ) nanoparticles in outdoor mesocosms using 1) 1-time pulse addition CeO2 nanoparticles, representative accidental release, and 2) continuous, low-level press via effluent. led rapid nanoparticle floc formation, which appeared preferentially deposit on periphyton low-energy areas downstream from location input, likely as a result gravitational sedimentation. Floc formation limited concentration suspended water <5% target subsequent movement. In contrast, higher concentrations (77% target) water, possibly stabilization through interaction with dissolved organic carbon. Smaller aggregates adsorb surfaces turbulent sections, where Ce were highest press, stochastic encounter surface. Streams containing lead aquatic organisms over greater spatial extent than similar amount an release. Exposure must take into account these mechanisms controlling transport depositional processes.