Profiling the Vertical Transport of Microplastics in the West Pacific Ocean and the East Indian Ocean with a Novel in Situ Filtration Technique

Abstract

A new technique involving large-volume (10 m 3 ) samples of seawater was used to determine the abundance of microplastics (MPs) in the water column in the West Pacific Ocean and the East Indian Ocean. Compared to the conventional sampling methods based on smaller volumes of water, the new data yielded abundance values for the deep-water column that were at least 1−2 orders of magnitude lower. The data suggested that limited bulk volumes currently used for surface sampling are insufficient to obtain accurate estimates of MP abundance in deep water. Size distribution data indicated that the lateral movement of MPs into the water column contributed to their movement from the surface to the bottom. This study provides a reliable dataset for the water column to enable a better understanding of the transport and fate of plastic contamination in the deep-ocean ecosystem.

The fate of plastic in the ocean environment – a minireview

“…77,78 However, PMD sinking uxes are largely understudied and the deposition mechanisms by which the microplastics reach the sediments is not yet fully understood. [79][80][81][82][83][84][85][86] It is also unclear if sunken (but previously oating) PMD remains at the seaoor or if sedimented plastics could become aoat again once the coating biolm is (partially) degraded. 4 Indeed, the ndings of an abundance of suspended PMD in the mid water column 79,86 begs the question if plastics may not only oat or sink but might also oscillate in the water column.…”

“…Also, data from high-volume sampling (10 m 3 ) suggest that the typical low-volume samples (<1 m 3 ) might be insufficient to estimate suspended PMD. 84 Further data on suspended and sedimented PMD and a better understanding on underlying processes determining vertical PMD uxes are clearly needed for well-balanced PMD budgets.…”

<em> </em>Current Research on Microbe-Plastic Interactions in the Marine Environment

“…Observations of low-density plastics resting on the seafloor or buried in sediments have been reported since the mid-1970's [293][294][295] . Despite that most plastic debris found in the marine environment are less dense than seawater 295,296 , recently these should-be-buoyant polymers have also been collected from the deeper layers of the water column [297][298][299][300][301] , demonstrating the 'fallout' of plastics from surface waters 301 . Due to the rapid colonisation of marine plastics -including by calcareous animals and various types of algae that can cover the plastics with thick, filamentous growth 89,266,302,303 -the overall density of biofouled particles may exceed that of seawater, causing them to lose buoyancy and sink, as observed in field investigations 89,302,303 .…”

The Story of Plastic Pollution: From the Distant Ocean Gyres to the Global Policy Stage

“…Plastic debris present in deep-sea sediments and organisms (van Cauwenberghe et al, 2013;Woodall et al, 2014;Fischer et al, 2015) demonstrate a vertical flux. Still, few studies have sampled vertical profiles of plastic across the water column (Choy et al, 2019;Li et al, 2020). One such study predicts that the highest concentrations are at the surface, and that concentrations change exponentially with depth (Li et al, 2020).…”

“…Still, few studies have sampled vertical profiles of plastic across the water column (Choy et al, 2019;Li et al, 2020). One such study predicts that the highest concentrations are at the surface, and that concentrations change exponentially with depth (Li et al, 2020). Due to its sheer volume, the water column is likely an underappreciated reservoir of microplastics in the ocean (Choy et al, 2019).…”