668 / 2024-09-18 21:49:40
Effects and Mechanisms of Titanium Dioxide Nanoparticles on Arsenic Metabolism and Toxicity in Marine Organisms
Titanium Dioxide Nanoparticles,mussels,Arsenic Metabolism,Toxicity,micoalgae
Session 57 - Contaminants across the marine continuum: behavior, fate and ecological risk assessment
Abstract Accepted
The increasing use of titanium dioxide nanoparticles (nTiO2) and their leakage into aquatic environments pose significant ecological risks. A major concern is that nTiO2 can alter arsenic (As) metabolism in marine organisms, affecting bioaccumulation, speciation, and detoxification processes. This study explores the impact of nTiO2 on As metabolism and toxicity in the mussel Perna viridis and the microalgae Phaeodactylum tricornutum. In mussels, nTiO2 exposure significantly increased As accumulation and shifted the balance between inorganic and organic arsenic, leading to reduced methylation and detoxification. The inhibition of As metabolism was linked to decreased glutathione (GSH) content and reduced glutathione S-transferase (GST) activity. Additionally, the adsorption properties of nTiO2 likely disrupted arsenic distribution, further hindering biotransformation and increasing toxicity by impairing osmotic regulation. In Phaeodactylum tricornutum, the joint toxicity of nTiO2 and arsenate (As(V)) varied with their concentration ratios. A synergistic effect was observed at a toxic unit (TU) ratio of 1:4, where nTiO2 enhanced arsenic accumulation by promoting the expression of phosphate transporter genes and suppressing genes involved in arsenic methylation. At higher TU ratios (4:1), reduced arsenic accumulation and improved biotransformation from toxic inorganic to non-toxic organic forms were noted, indicating partial additive or antagonistic effects. These findings highlight the crucial role of concentration ratios and biological responses in evaluating the environmental risks of nTiO2, which may increase As toxicity in marine organisms and disrupt its biogeochemical cycling.