title: TiO2 nanoparticles in the marine environment: Physical effects responsible for the toxicity on algae Phaeodactylum tricornutum.
abstract: Nanoscale titanium dioxide (nTiO2) has been widely used in cosmetics, catalysts, varnishes, etc., which is raising concerns about its potential hazards to the ecosystem, including the marine environment. In this study, the toxicological effect of nTiO2 on the marine phytoplankton Phaeodactylum tricornutum was carefully investigated. The results showed that nTiO2 at concentrations ≥20mg/L could significantly inhibit P. tricornutum growth. The 5-day EC50 of nTiO2 to P. tricornutum growth is 167.71mg/L. Interestingly, nTiO2 was found to exert its most severe inhibition effects on the first day of exposure, at a lower EC50 of 12.65mg/L. During the experiment, nTiO2 aggregates were found to entrap algae cells, which is likely responsible for the observed toxic effects. Direct physical effects such as cell wall damage from the algae entrapment were confirmed by flow cytometry and TEM imaging. Moreover, low indirect effects such as shading and oxidative stress were observed, which supported the idea that direct physical effects could be the dominant factor that causes nTiO2 toxicity in P. tricornutum. Our research provides direct evidence for the toxicological impact of nTiO2 on marine microalgae, which will help us to build a good understanding of the ecological risks of nanoparticles in the marine environment.
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China; Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.
authors.forename: Yixiang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China; Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China; Joint Center for Global Change Studies (JCGCS), Beijing 100875, China. Electronic address: zhu.xiaoshan@sz.tsinghua.edu.cn.
authors.forename: Xiaoshan
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.
authors.forename: Yongmin
authors.initials: Y
authors.lastname: Lao
authors.affiliation: Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055, China.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Lv
authors.affiliation: Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Tao
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China; Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.
authors.forename: Boming
authors.initials: B
authors.lastname: Huang
authors.affiliation: School of Life Science, Shenzhen University, Shenzhen 518060, China.
authors.forename: Jiangxin
authors.initials: J
authors.lastname: Wang
authors.affiliation: Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China. Electronic address: caizh@sz.tsinghua.edu.cn.
authors.forename: Zhonghua
authors.initials: Z
authors.lastname: Cai
mesh_terms: D017377:Diatoms / Q000187:drug effects*; D053768:Metal Nanoparticles / Q000633:toxicity*; D058086:Microalgae / Q000187:drug effects*; D010839:Phytoplankton / Q000187:drug effects*; D014025:Titanium / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D014025:Titanium
keywords: Growth inhibition; Marine environment; Microalgae Phaeodactylum tricornutum; Titanium dioxide (TiO(2)); Toxicity