title: Arsenate Accumulation, Distribution, and Toxicity Associated with Titanium Dioxide Nanoparticles in Daphnia magna.
abstract: Titanium dioxide nanoparticles (nano-TiO2) are widely used in consumer products. Nano-TiO2 dispersion could, however, interact with metals and modify their behavior and bioavailability in aquatic environments. In this study, we characterized and examined arsenate (As(V)) accumulation, distribution, and toxicity in Daphnia magna in the presence of nano-TiO2. Nano-TiO2 acts as a positive carrier, significantly facilitating D. magna's ability to uptake As(V). As nano-TiO2 concentrations increased from 2 to 20 mg-Ti/L, total As increased by a factor of 2.3 to 9.8 compared to the uptake from the dissolved phase. This is also supported by significant correlations between arsenic (As) and titanium (Ti) signal intensities at concentrations of 2.0 mg-Ti/L nano-TiO2 (R = 0.676, P < 0.01) and 20.0 mg-Ti/L nano-TiO2 (R = 0.776, P < 0.01), as determined by LA-ICP-MS. Even though As accumulation increased with increasing nano-TiO2 concentrations in D. magna, As(V) toxicity associated with nano-TiO2 exhibited a dual effect. Compared to the control, the increased As was mainly distributed in BDM (biologically detoxified metal), but Ti was mainly distributed in MSF (metal-sensitive fractions) with increasing nano-TiO2 levels. Differences in subcellular distribution demonstrated that adsorbed As(V) carried by nano-TiO2 could dissociate itself and be transported separately, which results in increased toxicity at higher nano-TiO2 concentrations. Decreased As(V) toxicity associated with lower nano-TiO2 concentrations results from unaffected As levels in MSFs (when compared to the control), where several As components continued to be adsorbed by nano-TiO2. Therefore, more attention should be paid to the potential influence of nano-TiO2 on bioavailability and toxicity of cocontaminants.
authors.affiliation: Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences , Xiamen 361021, China.|University of Chinese Academy of Sciences , Beijing 100049, China.
authors.forename: Mengting
authors.initials: M
authors.lastname: Li
authors.affiliation: Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences , Xiamen 361021, China.|Stockbridge School of Agriculture, University of Massachusetts , Amherst, Massachusetts 01003, United States.
authors.forename: Zhuanxi
authors.initials: Z
authors.lastname: Luo
authors.affiliation: Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences , Xiamen 361021, China.
authors.forename: Yameng
authors.initials: Y
authors.lastname: Yan
authors.affiliation: Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences , Xiamen 361021, China.|Stockbridge School of Agriculture, University of Massachusetts , Amherst, Massachusetts 01003, United States.
authors.forename: Zhenhong
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences , Xiamen 361021, China.
authors.forename: Qiaoqiao
authors.initials: Q
authors.lastname: Chi
authors.affiliation: Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences , Xiamen 361021, China.
authors.forename: Changzhou
authors.initials: C
authors.lastname: Yan
authors.affiliation: Stockbridge School of Agriculture, University of Massachusetts , Amherst, Massachusetts 01003, United States.
authors.forename: Baoshan
authors.initials: B
authors.lastname: Xing
mesh_terms: D000818:Animals; D001149:Arsenates; D001151:Arsenic; D003621:Daphnia; D053768:Metal Nanoparticles / Q000633:toxicity; D008670:Metals; D053758:Nanoparticles / Q000633:toxicity; D014025:Titanium / Q000633:toxicity
chemical_list: D001149:Arsenates; D008670:Metals; D014025:Titanium; D001151:Arsenic