Fate of river-derived microplastics from the South China Sea: Sources to surrounding seas, shores, and abysses

Preliminary assessment of microplastic in rhizosphere and non-rhizosphere region of mangrove at four locations along Karachi coast, Pakistan

Mangrove ecosystem faces significant threats from the various pollutants including microplastic (MPs). The aim of this study was to assess variations in MP distribution in mangrove sediments of rhizosphere (R) and non-rhizosphere (NR) regions. A total of 14,960 MP particles were identified from Sandspit backwater (SS-1 & SS-2) and Creek areas (PQ & KC). Notably, the NR showed higher MP counts (7848) compared to the R region (7112). Analysis revealed variations in MP types, with beads being predominant in both R and NR, followed by film, fiber, and fragments. KC exhibited highest MP contamination, followed by PQ, SS-2, and SS-1. Fourier-transform infrared (FTIR) analysis confirmed the presence of polyethylene terephthalate and polyethylene in sediments samples. This first detailed report on MP in mangrove sediments and other limited studies from Pakistan establishes the widespread distribution of MPs in the coastal area and provide a baseline for further elaboration in future.

Research progress on occurrence characteristics and source analysis of microfibers in the marine environment

Synthetic microfiber pollution is a growing concern in the marine environment. However, critical issues associated with microfiber origins in marine environments have not been resolved. Herein, the potential sources of marine microfibers are systematically reviewed. The obtained results indicate that surface runoffs are primary contributors that transport land-based microfibers to oceans, and the breakdown of larger fiber plastic waste due to weathering processes is also a notable secondary source of marine microfibers. Additionally, there are three main approaches for marine microplastic source apportionment, namely, anthropogenic source classification, statistical analysis, and numerical simulations based on the Lagrangian particle tracking method. These methods establish the connections between characteristics, transport pathways and sources of microplastics, which provides new insights to further conduct microfiber source apportionment. This study helps to better understand sources analysis and transport pathways of microfibers into oceans and presents a scientific basis to further control microfiber pollution in marine environments.