Microplastics could be hampering the ocean’s ability to capture carbon

Recent research has unveiled a concerning reality about microplastics in our oceans. Contrary to popular belief, these tiny particles are not confined to just the surface but are present throughout the water column, including the deepest ocean depths. This revelation has significant implications for the ocean’s role in carbon sequestration.

Tracy Mincer from Florida Atlantic University, along with his team, conducted a comprehensive analysis of microplastic data collected from nearly 2000 locations worldwide over the past decade. While previous studies mainly focused on surface microplastics, this review included samples from various depths, revealing a widespread distribution of these particles.

The study uncovered microplastics in every location surveyed, even in the Mariana Trench, where astonishingly high concentrations were found nearly 7 kilometers below the surface. What surprised researchers the most was the even distribution of the smallest plastic particles throughout the water column, instead of just floating at the surface or sinking to the bottom.

Aron Stubbins from Northeastern University highlighted that these microplastics contribute significantly to the carbon content in the ocean. In regions with lower biological activity, such as depths of 2000 meters, microplastics can account for up to 5% of the carbon present. This finding raises concerns about the impact of buoyant plastics on the ocean’s carbon sequestration processes.

One potential consequence is the interference of plastic ingestion by plankton with the natural carbon sinking process. This disruption could hinder the ocean’s ability to absorb CO₂ from the atmosphere through the biological carbon pump. However, the exact extent of this effect remains uncertain, as researchers are still unraveling the complexities of microplastic distribution in the ocean.

Douglas McCauley from the University of California Santa Barbara emphasized the importance of considering microplastics in ocean studies to better understand marine ecosystems. The survey’s findings shed light on discrepancies between estimated plastic inputs into the ocean and actual measurements, indicating that microplastics are dispersed across the water column rather than disappearing.