三种硅藻对微塑料沉降行为的影响研究OACSCD

The vertical transport of microplastics(MPs)in marine environments is influenced by various biological factors.However,the mechanisms underlying the phytoplankton-mediated settling behaviors of MPs remain poorly understood.This study combined microscopic observations with simulations to investigate the effects of the plank-tonic diatom Chaetoceros gracilis and the benthic diatoms,Nitzschia sp.and Navicula sp.,on aggregate formation and settling behavior in MPs.These included buoyant polypropylene MPs(PP-MPs),polyethylene MPs(PE-MPs),and non-buoyant polyamide MPs(PA-MPs).Results demonstrated that both PE-MPs and PP-MPs were encapsulat-ed within dense structures formed by the extracellular polymeric substances secreted by Nitzschia sp.and Navicula sp.Diatom colonization significantly increased the density of PE-MPs,while PA-MPs exhibited the maximal set-tling velocity with C.gracilis treatment.The MPs-biofouling model developed in this study revealed that biofilm density critically influences the settling patterns of MPs.These findings elucidate the regulatory mechanisms un-derlying the effects of diatom-mediated bio-aggregation on the sedimentation patterns of marine MPs,providing theoretical foundations for understanding the coastal transport dynamics of MPs.