Toxic response of the freshwater green algae Chlorella pyrenoidosa to combined effect of flotation reagent butyl xanthate and nickel

Hao Li (1) , Jun Yao (1) , Robert Duran (2) , Jianli Liu (1) , Ning Min (1) , Zhihui Chen (1) , Xiaozhe Zhu (1) , Chenchen Zhao (1) , Bo Ma (1) , Wancheng Pang (1) , Miaomiao Li (1) , Ying Cao (1) , Bang Liu (1)

1 China University of Geosciences [Beijing]
2 IPREM - Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux

Butyl Xanthate (BX) is a typical flotation reagent used to extract non-ferrous nickel ores, discharged into the surrounding environment of mining areas in large quantities. However, few studies have focused on the toxicity of combined pollution of BX and nickel (Ni) on aquatic plants, especially phytoplankton, the main producer of aquatic ecosystems. The toxicity and potential mechanism of single and combined pollution of BX and Ni at different concentrations (0–20 mg L−1) on typical freshwater algae (Chlorella pyrenoidosa) were studied. BX slightly stimulated the growth of C. pyrenoidosa on the first day, but Ni and Ni/BX mixture significantly inhibited it during incubation. Results showed that the inhibition rate (I) of the pollutants on the growth of C. pyrenoidosa followed the order: Ni/BX mixture > Ni > BX. The 96-h 20% effective inhibitory concentrations (96h-EC20) of Ni and BX on C. pyrenoidosa growth were 3.86 mg L−1 and 19.25 mg L−1, respectively, indicating C. pyrenoidosa was sensitive to pollutants. The content of total soluble protein (TSP) and chlorophyll a (Chl-a) changed significantly, which may be caused by the damage of pollutants to cell structures (cell membranes and chloroplasts). In addition, the I of pollutants on C. pyrenoidosa growth was related to dose, superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA). The increasement of reactive oxygen species (ROS), antioxidant enzymes (SOD and CAT), and MDA content, suggested C. pyrenoidosa suffered from oxidative stress, leading to lipid oxidation. These results will help to understand the toxicity mechanism of pollutants in typical mining areas and assess the environmental risks of pollutants to primary producers in aquatic ecosystems

Keywords: Butyl xanthate; Nickel; Combined pollution; Oxidative stress; Lipid oxidation

Domains: Material chemistry; Polymers; Theoretical and/or physical chemistry; Analytical chemistry

Hao Li, Jun Yao, Robert Duran, Jianli Liu, Ning Min, et al.. Toxic response of the freshwater green algae Chlorella pyrenoidosa to combined effect of flotation reagent butyl xanthate and nickel. Environmental Pollution, 2021, 286, pp.117285. ⟨10.1016/j.envpol.2021.117285⟩. ⟨hal-03237415⟩