Employing Density Separation to Characterise Microplastic Contamination in Coastal Wetland Ecosystems

Résumé fourni par la source

The study investigates microplastic (MP) contamination across three coastal wetland ecosystems: seagrass, saltmarsh, and mangroves. The study aimed to employ a density separation technique to characterise the extent and composition of MP contamination, providing a comprehensive analysis of the trends in distribution and morphology. Despite the growing body of research on MPs, there remains a lack of detailed, localised studies focusing on coastal wetland ecosystems, which may be effective sinks for MP pollution, acting as a Nature-based Solution. Seagrass meadows exhibited a predominant input of MPs from marine sources, with fibres accounting for 60.5% of the total MP content. Saltmarsh sediments showed a similar dominance of fibres (62.3%), linked to wastewater inputs. Mangroves, however, displayed the highest MP concentration, dominated by fragments (59.7%), likely due to the fragmentation of larger plastic debris deposited during storm surges. MP colour patterns were also ecosystem-specific, with red MPs being prevalent in seagrass (55.0%) and saltmarsh (39.9%) and transparent being most prevalent in mangroves (73.4%). The study emphasises the ecological implications of MP contamination, including risks to marine species and the potential disruption of sediment biogeochemistry, warranting further investigation into the long-term effects on coastal ecosystems. Seagrass beds trap MPs primarily from marine sources, with fibres potentially dominating due to synthetic rope degradation and wastewater inputs. Saltmarshes retain MPs differently based on plant species, with Salicornia marshes showing the highest MP concentration. Mangroves exhibit the highest MP concentration, particularly near shorelines, with fragments being common potentially due to storm-driven debris and boat traffic.

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