Microplastics in the water column: their composition and dynamics

Abstract

Nowadays, it is known that of the more than 400 million tons of plastic produced each year, approximately 52 million tons end up being released into the environment annually due to poor waste management. It is estimated that over 170 trillion plastic particles are floating in the world's oceans. Additionally, significant data exists regarding the presence of plastics and microplastics in marine sediments. However, there is limited data on the presence and abundance of marine microplastics in the water column, which holds a total volume of 1,347 million km³ distributed across the planet. This chapter compiles the main studies conducted to date that confirm the presence of small microplastics floating in the water column, especially those smaller than 500 µm. These particles have been observed at various depths and in different oceans, with compositions similar to those found on the surface. This highlights the likelihood that the contribution of these vast oceanic zones has been underestimated so far and may represent a much higher rate of plastic particle accumulation than previously thought, potentially constituting a major global reservoir of plastic material.