A new method for removing plankton from particles is facilitating the monitoring of microplastics in seawater.
Determining the quantity and quality of microplastics in seawater is crucial
Accurate methods for identifying microplastics in seawater are becoming increasingly essential to assess the severity of pollution. However, the challenge lies in separating these particles from the aquatic environment’s plankton. While certain techniques can remove these organisms from polymeric particles, they often degrade them, hindering effective classification. This affects the accuracy of monitoring and, in turn, the scientific data needed to inform policy decisions.
Researchers at Flinders University in Adelaide, Australia, have made significant progress in a recent breakthrough. The study examines the effectiveness of various chemical methods to digest plankton samples without damaging microplastics. The researchers tested different digestive agents (acidic, alkaline, enzymatic, and oxidative) on a range of common plastics (polyethylene, polypropylene, polystyrene, polyethylene terephthalate, and polyamide) found in environmental samples.
Each agent produced varying effects on the physical and chemical structure of the microplastics. Some digestive agents were more effective at removing biological material without compromising the integrity of the particles, while others caused significant alterations, making it difficult to identify them accurately. For example, acidic and oxidative treatments showed a stronger ability to degrade organic matter, but also damaged the surface of the microplastics, compromising subsequent analysis.
The enzymatic treatment with Proteinase-K (produced by the fungus Tritirachium album Limber) yielded the most promising results. Around 75% of the plankton was removed without causing significant damage to the microplastics. This method proved to be the most effective in preserving the integrity of the particles, particularly for PE and PP, which are more susceptible to chemical damage.
The research underscores the importance of selecting the right chemical method to ensure that microplastics in seawater can be recovered intact from environmental samples. This is crucial for studies aiming to determine the concentration and distribution of microplastics in aquatic ecosystems.
