Effects of grain size component and concentration of turbidity current on the deposition of different types of microplastics: An experimental study

Submarine turbidity currents are an important part of the marine sediment source-sink system and a substantial driving force for transporting sediment into the deep sea, posing extensive impacts on deep-sea sedimentation, resources, and the environment. Different types of turbidity currents arise from variations in triggering mechanisms, grain size component, and concentration. Although turbidity currents are widely recognized as carriers of microplastic transport, the effects of turbidity currents with different silt/clay ratios on the migration and deposition of various microplastics remain unclear. Indoor flume experiments were conducted to simulate the deposition of different microplastics carried by turbidity currents. Results show that turbidity current in high concentration with rich clay content could significantly enhance the downstream transport ability of microplastics, which was influenced by the material and shape of microplastics. Higher-density microplastics were generally transported farther than low-density ones, whereas granular microplastics tended to deposit upstream, while fragmentary and fibrous microplastics were carried over longer distances.