Revealing microplastic and anthropogenic microparticles contamination in tidal blue carbon ecosystems from eastern Brazil

We provide information about the accumulation of microplastic and other anthropogenic microparticles (AMP) in tidal blue carbon ecosystems from Eastern Brazil. This study analyzed the accumulation of AMP in 40 sediment samples extracted from tropical Spartina marsh (2 cores: CM1 and CM2) and mangrove (1 core: CAB) from Todos os Santos Bay (TSB, Bahia, Brazil). The main objective was to identify differences in AMP accumulation between mangrove and Spartina salt marsh cores in order to understand their different roles in AMP retention; and evaluate if Spartina marshes act as stronger AMP sinks than mangroves. The average AMP abundance was at least 38 % higher in saltmarshes compared to mangroves. Micro-Raman spectroscopy was applied to determine the chemical composition of the different collected samples, thereby enabling a detailed investigation of their structural and compositional features. Fibers represent the dominant category, likely due to the large widespread use of synthetic fibers, insufficient wastewater treatment and high levels of fishing activities in the area. The predominant color in all cores is blue (41.6 %) and transparent (20.0 %), the predominant particle size in all cores is between 0 and 1 mm. Organic matter (%OM) and mud content (%M) did not influence AMP concentration. This work improves the understanding of the distribution and consequences of AMP in South American mangrove and salt marsh ecosystems, highlighting the need for collective, comprehensive efforts to mitigate their effects, such as improving the efficiency of wastewater management and other human uses and mismanagement in TSB.