This study aimed to evaluate the bioaccumulation and enrichment of heavy metals in dominant microalgae and assess the potential ecological risk to the microalgae located at the northern region of Taihu Lake, China, a shallow freshwater lake. The concentrations of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in water and microalgae (predominant cyanophyta) collected from the north of Taihu Lake were analyzed. Subsequently, enrichment factors (EF) for heavy metals in microalgae relative to water were calculated. The concentrations and EF values of heavy metals were significantly higher in water and microalgae from the northern region compared with other regions for all the metals except As and Hg. Among the metals, Pb and Cd possessed higher enrichment levels, approx. 200 and 400 for Pb and Cd, respectively. This suggested that Pb and Cd had stronger chemisorption on microalgae, even though present at lower concentrations. Moreover, Ni and Zn in microalgae from the north of the lake also exhibited risk to the ecosystem owing to their high concentrations. In general, the microalgae tended to enrich Pb, Cd, Ni, and Zn by biosorption and bioaccumulation and thus exert a risk to the ecosystem and human populations.
Keywords: Bioaccumulation; Ecological risk assessment; Heavy metals; Microalgae; Taihu Lake.