Researchers from the Universitat de Girona (UdG) recently presented innovative research at the 15th International Symposium on River Sedimentation (ISRS) held in Florence from September 5th to 8th, 2023. The ISRS, a prestigious triennial event initiated by the Chinese Hydraulic Engineering Society (CHES) with UNESCO's support, offers a critical platform for scientists, engineers, and policymakers to discuss advancements in sediment study and management.

Dr. Teresa Serra from UdG's Department of Physics presented a noteworthy study titled "Microplastic Retention by Lagoons Surrounded by Vegetation in Wetland Areas." This research, conducted as part of the Plastikhum project, explores the effectiveness of vegetation in wetlands at trapping microplastics (MP).

Background and Motivation

The exponential increase in plastic production over the past 70 years has led to significant accumulation of microplastics in various ecosystems, including water bodies and sediments. Wetlands, with their shallow waters and vegetative coverage, are particularly susceptible to microplastic contamination from riverine and marine flooding. Understanding how these environments can retain microplastics is crucial for developing strategies to mitigate pollution.

Experimental Approach

The experiments were conducted in a laboratory flume measuring 500 cm in length, 40 cm in width, and 50 cm in height. Two platforms created a lagoon zone surrounded by shallow areas with different lengths of vegetation patches (Lpatch). The study considered four Lpatch scenarios and a control without vegetation. The research examined the retention of four types of microplastics: PET fibers and PA fragments of varying sizes.

A unidirectional flow transported a plume containing both sediments and microplastics into the flume. Sediment traps were placed along the flume's length to measure the concentration of particles at various points. The setup aimed to simulate natural flooding events and analyze how different lengths of vegetative patches impact microplastic retention.

Findings and Implications

The results demonstrated that the concentration of microplastic particles decreased exponentially with distance from the source. The presence of vegetation significantly enhanced microplastic retention, with longer vegetative patches providing greater protection for the lagoon. The study found that patches longer than 5 times the water depth (Lpatch > 5 hw) were particularly effective in shielding the lagoon from microplastics.

Large PA fragments were predominantly retained in the shallow zones, while smaller fragments and fibers were transported further. For vegetation patches shorter than 5 hw, the lagoon received higher microplastic concentrations, indicating reduced protective efficacy.

Dr. Serra's research highlights the critical role of vegetative patches in wetlands for mitigating microplastic pollution. The study underscores the importance of maintaining and restoring vegetative areas around lagoons to enhance their natural filtration capabilities. These findings provide valuable insights for environmental management and policy-making aimed at reducing microplastic contamination in aquatic ecosystems.

The participation of the Universitat de Girona at ISRS 2023 emphasizes the institution's dedication to addressing environmental challenges through scientific research. Dr. Serra's contribution offers crucial knowledge that can inform future efforts to protect water bodies from the pervasive threat of microplastics.

For more detailed information, please refer to the article "Microplastic Retention by Lagoons Surrounded by Vegetation in Wetland Areas" presented at ISRS 2023.