Abstract：Silver nanoparticles (AgNPs) were synthesized via the reduction of silver nitrate by sodium borohydride and stabilized by polyvinyl alcohol, and the particle size was (7 ± 3) nm. The effects of AgNPs on the growth, photosynthesis, and respiration of Chlorella vulgaris were studied using the methods of cell count and oxygen uptake and production rates, and the inhibition of chlorophyll a was also investigated. The respiration of Chlorella vulgaris was completely inhibited by AgNPs of 3mg/L in 2h, and inhibition rate of the growth was 93% by AgNPs of 4mg/L when AgNPs were added in the dark. However, when AgNPs were added in the light, the photosynthesis of Chlorella vulgaris were inhibited when AgNPs of 10mg/L were used, and under this condition, inhibition rate of the growth reached 90%. In addition, 77% of chlorophyll a was inhibited by 10mg/L AgNPs. AgNPs had a strong effect on respiration of Chlorella vulgaris and might inhibit the synthesis of chlorophyll a or destroy the structure of chloroplast to inhibit the photosynthesis. The light could obviously reduce the toxicity of AgNPs.
