Silver nanoparticles (AgNPs) were inevitably discharged into aquatic environments due to their abundant use in antibacterial products. Previous studies documented that AgNPs may have adverse effects on various aquatic organisms in different trophic levels. However, most of these studies were performed with pure cultures at high AgNPs concentration and for a short time exposure, thus the toxicity of AgNPs in these studies may not represent the one in natural complex environments. 

Supervised by Prof. LI Wei and Prof. YIN Liyan, JIANG Hongsheng, Ph.D student from Wuhan Botanical Garden, investigated the chronic effects of AgNPs on aquatic ecosystem under a real natural condition by setting microcosms.  

After 90 days exposure, the results showed that the surface layer of sediment was the main sink of Ag element for both AgNPs and AgNO₃. Both aquatic plant (Hydrilla verticillata) and animals (Gambusia affinis and Radix spp) significantly accumulated Ag. 

With short-term treatment, phytoplankton biomass was affected by AgNO₃ but not by AgNPs. The nitrification rate and its related microbe (Nitrospira) abundance significantly decreased.  

AgNPs and AgNO₃ may affect the nitrogen cycle and affect the environment and, since they might be also transferred to food web, they represent a risk for health. 

This research was supported by the National Natural Science Foundation of China and the National Key Basic Research and Development Program. 

Relevant research results entitled “The effect of chronic silver nanoparticles on aquatic system in microcosms” were published in Environmental Pollution.