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Size-dependent effect of microplastics on toxicity and fate of diclofenac in two algae

Journal of Hazardous Materials 2023 35 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Tengda Ding, Xiaotong Huang, Liyan Wei, Juying Li

Summary

This study investigated how different sizes of polystyrene microplastics affect two species of algae and interact with the common pharmaceutical pollutant diclofenac. Researchers found that the smallest microplastics caused the most significant growth inhibition in algae, and the combined presence of microplastics and diclofenac could alter how each pollutant behaves. The findings underscore how microplastics can change the toxicity and environmental fate of other water contaminants.

Polymers

Microplastics (MPs) are frequently detected in natural waters and usually acted as vectors for other pollutants, leading to possible threats to aquatic organisms. This study investigated the impact of polystyrene MPs (PS MPs) with different diameters on two algae Phaeodactylum tricornutum and Euglena sp., and the combined toxicity of PS MPs and diclofenac (DCF) in two algae was also studied. Significant inhibition of P. tricornutum was observed after 1 d exposure of 0.03 µm MPs at 1 mg L, whereas the decreased growth rate of Euglena sp. was recovered after 2 d exposure. However, their toxicity decreased in the presence of MPs with larger diameters. The oxidative stress contributed a major for the size-dependent toxicity of PS MPs in P. tricornutum, while in Euglena sp. the toxicity was mainly caused by a combination of oxidative damage and hetero-aggregation. Also, PS MPs alleviated the toxicity of DCF in P. tricornutum and the DCF toxicity continually decreased as their diameter increased, whereas the DCF at environmentally concentration could weaken the toxicity of MPs in Euglena sp. Moreover, the Euglena sp. revealed a higher removal for DCF, especially in the presence of MPs, but the higher accumulation and bioaccumulation factors (BCFs) indicated a possible ecological risk in natural waters. The present study explored discrepancy on the size-dependent toxicity and removal of MPs associated with DCF in two algae, providing valuable data for risk assessment and pollution control of MPs associated with DCF.

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