The public often associates ocean plastic accumulation with the Great Pacific Garbage Patch (GPGP), the global symbol for marine plastic pollution. Since the world’s oceans are interconnected by circulating currents, the Pacific is likely not the only region where floating waste gathers. The Atlantic Ocean, bordered by densely populated continents, was investigated to see if it harbors a similar zone of plastic concentration. This investigation confirmed that the dynamic forces of ocean circulation have created a comparable, though distinct, accumulation zone in the North Atlantic.
Confirmation of the Atlantic Accumulation Zone
Scientific data confirms the existence of a high-concentration area for marine debris in the North Atlantic Ocean. This region is formally known as the North Atlantic Subtropical Gyre Accumulation Zone, or informally as the North Atlantic Garbage Patch (NAGP). This area of trapped debris is located within the vast expanse of the North Atlantic Subtropical Gyre.
Geographically, the accumulation zone is situated in the western Atlantic, spanning the subtropical latitudes. It overlaps significantly with the Sargasso Sea, a unique body of water characterized by calm conditions and dense floating mats of Sargassum seaweed. Studies using surface plankton net tows consistently show the highest concentrations of buoyant plastic pieces here. The presence of this zone is directly linked to large-scale convergence in surface currents, fulfilling ocean circulation predictions.
The Role of the North Atlantic Gyre in Concentration
The creation of this debris field is a direct consequence of the ocean’s complex circulation system, specifically the North Atlantic Subtropical Gyre. A gyre is a large system of rotating ocean currents, driven by global winds and the Earth’s rotation (the Coriolis effect). The North Atlantic Gyre rotates clockwise, acting like a colossal, slow-moving oceanic whirlpool.
Four primary currents define the boundaries of this system: the Gulf Stream (west), the North Atlantic Current (north), the Canary Current (east), and the North Equatorial Current (south). The flow of these strong boundary currents pushes surface water and floating material toward the gyre’s less dynamic center. This creates a region of convergence where the water sinks, but buoyant debris, particularly plastic, is trapped at the surface. The resulting accumulation zone is a stable area where marine litter is continuously collected and retained.
Density and Composition Compared to the Pacific Patch
While the Atlantic zone exists due to the same physical trapping mechanism as the Pacific patch, its nature differs significantly in visibility and composition. The North Atlantic Subtropical Gyre Accumulation Zone has a lower overall density of large, recognizable debris compared to the Great Pacific Garbage Patch (GPGP). The GPGP has a higher proportion of larger items; studies indicate that up to 75% of its total mass consists of items larger than five centimeters, including abandoned fishing gear.
In contrast, the Atlantic accumulation zone is largely dominated by microplastics, which are plastic pieces smaller than five millimeters. The vast majority of buoyant plastic collected in the North Atlantic are millimeter-sized fragments. This high concentration of fragmented material makes the patch difficult to see from a boat or satellite, leading scientists to describe it as a plastic “soup” or “smog” rather than a visible island of trash. Microplastics account for nearly all of the total particle count in the accumulation zone. Estimates suggest the total mass of microplastic floating in the North Pacific Gyre may be ten times greater than in the North Atlantic gyre.
Scientific Monitoring and Data Collection
Scientists track and quantify the plastic debris in the Atlantic through specialized sampling techniques adapted for measuring small particles. The primary method for assessing surface microplastics involves using a device called a Manta Trawl. This net is towed horizontally behind a vessel, with its rectangular opening designed to skim the top layer of the water column (typically the first 15 to 25 centimeters).
The Manta Trawl uses fine mesh, often around 335 micrometers, to effectively capture the millimeter-sized plastic fragments prevalent in the gyre. To ensure accurate measurement, the volume of water filtered is recorded using a flowmeter or calculated from the net’s opening size and distance traveled via GPS. Collected samples are then analyzed in laboratories to count, size, and identify the polymer type of the microplastics. This data is used to estimate the overall mass and distribution of plastic within the gyre. Remote sensing and computer modeling are also employed to predict and map debris movement, helping researchers determine the boundaries and persistence of the accumulation zone.