Marine Heatwaves\nExacerbate the Toxic Effects of Tire\nParticle Leachate on Microalgae

Additives leached from tire particles (TPs) after entering\nthe\nmarine environment inevitably interact with marine life. Marine heatwaves\n(MHWs) would play a more destructive role than ocean warming during\nthe interaction of pollutants and marine life. To evaluate the potential\nrisks of TPs leachate under MHWs, the physiological and nutrient metabolic\nendpoints of microalgae Isochrysis galbana were observed for 7 days while being exposed to TPs leachate at\ncurrent or predicted concentrations under MHWs. TPs leachate mainly\ncontained Zn and 6-PPD, which could be absorbed by microalgae mostly,\nespecially under MHWs. Additionally, TPs leachate increased the reactive\noxygen species content, activated the antioxidant system, impaired\nphotosynthesis and glycolysis, and decreased sugar and protein content.\n10 mg/L TPs leachate increased the lipid content and saturation. Meanwhile,\nmicroalgae under such TPs leachate were biased toward the synthesis\nof long-chain fatty acids and <i>Δ8</i> desaturation\npathway. MHWs promoted the positive effects of TPs leachate on microalgae\ngrowth at the current concentration but exacerbated the negative effects\nat the predicted concentration. Our study emphasizes the potential\nrisks of TPs leachate to marine primary production systems, especially\nif accompanied by the increasing intensity and frequency of extreme\nclimate events.