Variation in sediment particle properties gives rise to diverse settling velocities and distances, leading to distinct distributions of particle sizes in field sediments, while the impact of particle size on sediment toxicity is scarcely known. We investigated the variations in spiked-sediment toxicity across different particle sizes (<
20 μm, 63-180 μm, 180-500 μm, and original) with cypermethrin, one of the main toxicity contributors in sediment from South China, as the target compound and two invertebrates