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North Atlantic garbage patch
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The North Atlantic garbage patch is a garbage patch of human-made marine debris found floating within the North Atlantic Gyre, originally documented in 1972.[1] A 22-year research study conducted by the Sea Education Association estimates the patch to be hundreds of kilometers across, with a density of more than 200,000 pieces of debris per square kilometer.[2][3][4][5] The garbage originates from human-created waste traveling from rivers into the ocean and mainly consists of microplastics.[6] The garbage patch is a large risk to wildlife (and to humans) through plastic consumption and entanglement.[7]
There have only been a few awareness and clean-up efforts for the North Atlantic garbage patch, such as The Garbage Patch State at UNESCO and The Ocean Cleanup, as most of the research and cleanup efforts have been focused on the Great Pacific Garbage Patch, a similar garbage patch in the north Pacific.[8][9]
Characteristics
[edit]Location and size
[edit]The patch is located from 22°N to 38°N and its western and eastern boundaries are unclear.[5] The debris zone shifts by as much as 1,600 km (1,000 mi) north and south seasonally, and drifts even farther south during the El Niño-Southern Oscillation, according to the NOAA.[3] The patch is estimated to be hundreds of kilometers across in size,[3] with a density of more than 200,000 pieces of debris per square kilometer (one piece per five square metres, on average).[5][10] The concentration of plastic in the North Atlantic garbage patch has stayed mostly constant even though global plastic production has increased five-fold over the course of the 22-year study.[11] This may be caused by the plastics sinking beneath the surface or breaking down into pieces small enough to pass through the net that researchers have used to collect and study the material.[11] Because of this, it is thought that the size of the North Atlantic garbage patch could be an underestimate. It is likely that when the microplastics are taken into account, the patch could be as large as the Great Pacific Garbage Patch.[12]
Sources
[edit]The North Atlantic garbage patch originates from human-created waste that travels from continental rivers into the ocean.[13] Once the trash has made it into the ocean, it is centralized by gyres, which collect trash in large masses.[11] The surface of the garbage patch consists of microplastics such as polyethylene and polypropylene which make up common household items.[6] Denser material that is thought to exist under the surface of the ocean includes plastic called polyethylene terephthalate that is used to make soft drink and water bottles.[6] However, these denser plastics are not observed in the North Atlantic garbage patch because the methods to collect samples only capture the surface microplastics.[6]
Research
[edit]A joint study by the Sea Education Association, Woods Hole Oceanographic Institution, and the University of Hawaii at Manoa collected plastic samples in the western North Atlantic and Caribbean Sea from 1986 to 2008.[2] Nearly 7,000 students from the SEA semester program conducted 6,136 surface plankton net tows on board SEA's sailing research vessels over 22 years, yielding more than 64,000 plastic pieces, mostly fragments less than 10mm in size with nearly all lighter than 0.05g.[14][15] Nikolai Maximenko of the University of Hawaii in Honolulu developed a computer model to describe how plastics are accumulated from converging surface currents to form garbage patches.[14] The model uses data from more than 1,600 satellite-tracked trajectories of drifting buoys to map out surface currents.[5] The plastic data collected by the students at SEA validated Maximenko's model, and researchers were able to successfully predict plastic accumulation in the North Atlantic Ocean.[14]
A recent study published in December 2022 investigated the microbial communities found in the North Atlantic Garbage Patch and compared the data to the Great Pacific Garbage Patch. Researchers collected plastic debris from the garbage patch in 2019 and analyzed the microbes using 16S rRNA gene analysis. The microbes that were identified and the communities they formed were deemed the plastisphere of the garbage patch. Microbes were typically found on polyethylene (PE) and polypropylene (PP) particles. Because of this, the researchers also investigated the potential of the microbes to degrade the plastic and potentially contribute to decreasing the garbage patches. Based on the microbes identified, only 4.07% were members of genera that could degrade the plastics found in the garbage patch. Along with that, the bacteria were only known to degrade PE and not PP. The researchers concluded that more investigation is needed to find a natural way to combat the accumulation of plastic in the garbage patch.[16]
Negative effects
[edit]Since a large amount of plastic in the North Atlantic Garbage Patch is in the form of microplastics, it is easier for marine animals to ingest them. These small plastics can be mistaken for fish eggs. Along with that, the smaller pieces of microplastics can be ingested by animals that are towards the bottom of the food chain such as zooplankton. The plastic that accumulates in the zooplankton then builds up inside the organisms that eat them.[17] There has been little to no research on how microplastics can move up the food chain and potentially be magnified in larger organisms. However, it is predicted that the biomagnification of plastics in the food web will depend on how much plastic is ingested and retained, with retention being heavily dependent on the size of the plastic ingested.[18] This accumulation and potential biomagnification of plastic can lead to malnourished organisms and can be a threat to the biodiversity of the ocean. Along with that, the accumulation of microplastics in marine life can be transferred to humans when they consume contaminated organisms which could cause adverse health effects.[19]
A recent study conducted by The Ocean Cleanup and the Royal Netherlands Institute for Sea Research found that the levels of microplastics on the surface of the North Atlantic Garbage Patch are close to exceeding safe levels for sea life in the region. While the exact consequences of this are unknown, the researchers claim there could be significant adverse effects on marine life if something is not done to combat the issue.[20] Another study conducted in 2021 looked at the accumulation of chemicals and plastics in species that are in the middle of the food web in the North Atlantic. These species included Sardina pilchardus (sardines), Scomber spp., and Trachurus trachurus (mackerels). They found that while the concentrations of several chemicals inside the fish were lower than what is found in the same species in adjacent areas, they found that there were plastic pieces in the stomachs of 29% of the sampled organisms.[21]
Hurricane Larry in September 2021 deposited, during the storm peak, 113,000 particles/m2/day as it passed over Newfoundland, Canada. Back-trajectory modelling and polymer type analysis indicate that those microplastics may have been ocean-sourced as the hurricane traversed the North Atlantic garbage patch of the North Atlantic Gyre.[22]
Awareness and clean-up efforts
[edit]Few efforts have been made to clean up the North Atlantic Garbage Patch, as removing the microplastics "would likely cause as much harm as good because of all the other small creatures in the ocean that would get filtered out too".[11] On 11 April 2013, in order to create awareness, artist Maria Cristina Finucci founded The Garbage Patch State at UNESCO[8] –Paris in front of Director General Irina Bokova. The Garbage Patch State was first in a series of events under the patronage of UNESCO and of Italian Ministry of the Environment, sparking a series of art exhibits across the world used to bring attention to the size and severity of the garbage patches and incite awareness and action.[23]
Dutch inventor Boyan Slat and his nonprofit organization The Ocean Cleanup is developing technology to rid the oceans of plastic.[9] Cleanup is planned to start in the Great Pacific Garbage Patch first, and eventually move around to the other patches across the globe.[24] Aside from cleaning the microplastics from the oceans, the Ocean Cleanup is also developing technologies to remove larger pieces of plastic from rivers, which are largely attributed as the main sources of plastic in the ocean.[13]
See also
[edit]References
[edit]- ^ Carpenter, E.J.; Smith, K.L. (1972). "Plastics on the Sargasso Sea Surface, in Science". Science. 175 (4027): 1240–1241. doi:10.1126/science.175.4027.1240. PMID 5061243. S2CID 20038716.
- ^ a b "Mānoa: UH Mānoa scientist predicts plastic garbage patch in Atlantic Ocean | University of Hawaii News". manoa.hawaii.edu. Archived from the original on 28 October 2019. Retrieved 8 November 2019.
- ^ a b c Gorman, Steve (4 August 2009). "Scientists study huge ocean garbage patch". Perthnow.com.au. Archived from the original on 29 January 2011. Retrieved 10 May 2012.
- ^ "Scientists find giant plastic rubbish dump floating in the Atlantic". Perthnow.com.au. 26 February 2010. Archived from the original on 14 April 2012. Retrieved 10 May 2012.
- ^ a b c d Gill, Victoria (24 February 2010). "Plastic rubbish blights Atlantic Ocean". BBC News. Archived from the original on 27 August 2017. Retrieved 10 May 2012.
- ^ a b c d Orcutt, Mike (19 August 2010). "How Bad Is the Plastic Pollution in the Atlantic?". Popular Mechanics. Archived from the original on 19 August 2014. Retrieved 8 November 2019.
- ^ Sigler, Michelle (18 October 2014). "The Effects of Plastic Pollution on Aquatic Wildlife: Current Situations and Future Solutions". Water, Air, & Soil Pollution. 225 (11): 2184. Bibcode:2014WASP..225.2184S. doi:10.1007/s11270-014-2184-6. ISSN 1573-2932. S2CID 51944658.
- ^ a b "The garbage patch territory turns into a new state - United Nations Educational, Scientific and Cultural Organization". unesco.org. 22 May 2019. Archived from the original on 11 September 2017. Retrieved 5 November 2014.
- ^ a b "About". The Ocean Cleanup. Archived from the original on 3 March 2021. Retrieved 8 November 2019.
- ^ "Scientists find giant plastic rubbish dump floating in the Atlantic | Perth Now". 14 April 2012. Archived from the original on 14 April 2012. Retrieved 6 November 2019.
- ^ a b c d McNally, Jess (19 August 2010). "Massive North Atlantic Garbage Patch Mapped". Wired. ISSN 1059-1028. Archived from the original on 14 October 2019. Retrieved 5 November 2019.
- ^ "The Atlantic garbage patch - less-known than its Pacific sibling, equally deadly". Red, Green, and Blue. 12 May 2020. Archived from the original on 14 March 2023. Retrieved 15 March 2023.
- ^ a b "Rivers". The Ocean Cleanup. Archived from the original on 14 February 2020. Retrieved 8 November 2019.
- ^ a b c Law, Kara Lavender; Morét-Ferguson, Skye; Maximenko, Nikolai A.; Proskurowski, Giora; Peacock, Emily E.; Hafner, Jan; Reddy, Christopher M. (3 September 2010). "Plastic Accumulation in the North Atlantic Subtropical Gyre". Science. 329 (5996): 1185–1188. Bibcode:2010Sci...329.1185L. doi:10.1126/science.1192321. ISSN 0036-8075. PMID 20724586. S2CID 13552090.
- ^ Morét-Ferguson, Skye; Law, Kara Lavender; Proskurowski, Giora; Murphy, Ellen K.; Peacock, Emily E.; Reddy, Christopher M. (2010). "The size, mass, and composition of plastic debris in the western North Atlantic Ocean". Marine Pollution Bulletin. 60 (10): 1873–1878. Bibcode:2010MarPB..60.1873M. doi:10.1016/j.marpolbul.2010.07.020. PMID 20709339. Archived from the original on 12 May 2024. Retrieved 5 June 2024.
- ^ Tora, Dkawlma; Hentschel, Ute; Lips, Stefan; Schmitt-Jansen, Mechthild; Borchert, Erik (22 December 2022). "16s rRNA gene sequence analysis of the microbial community on microplastic samples from the North Atlantic and Great Pacific Garbage Patches" 2022.12.22.521553. bioRxiv 10.1101/2022.12.22.521553. doi:10.1101/2022.12.22.521553. S2CID 255097212. Archived from the original on 14 March 2023. Retrieved 20 April 2023.
{{cite journal}}: Cite journal requires|journal=(help) - ^ Center, Loggerhead Marinelife (18 November 2016). "Silent but Sneaky: How the North Atlantic Garbage Patch Threatens Marine Life". Loggerhead Marinelife Center. Archived from the original on 14 March 2023. Retrieved 15 March 2023.
- ^ Setälä, Outi; Lehtiniemi, Maiju; Coppock, Rachel; Cole, Matthew (2018), "Microplastics in Marine Food Webs", Microplastic Contamination in Aquatic Environments, Elsevier, pp. 339–363, doi:10.1016/b978-0-12-813747-5.00011-4, ISBN 978-0-12-813747-5, S2CID 133936423, archived from the original on 23 May 2023, retrieved 28 March 2023
- ^ Leal Filho, Walter; Hunt, Julian; Kovaleva, Marina (November 2021). "Garbage Patches and Their Environmental Implications in a Plastisphere". Journal of Marine Science and Engineering. 9 (11): 1289. doi:10.3390/jmse9111289. ISSN 2077-1312.
- ^ erika (11 August 2022). "North Atlantic Microplastic Concentrations May Exceed Safe Levels for Marine Life Without Intervention • Updates • The Ocean Cleanup". The Ocean Cleanup. Retrieved 15 March 2023.
- ^ da Silva, Joana M.; Alves, Luís M. F.; Laranjeiro, Maria I.; Bessa, Filipa; Silva, Andreia V.; Norte, Ana C.; Lemos, Marco F. L.; Ramos, Jaime A.; Novais, Sara C.; Ceia, Filipe R. (1 January 2022). "Accumulation of chemical elements and occurrence of microplastics in small pelagic fish from a neritic environment". Environmental Pollution. 292 (Pt B) 118451. doi:10.1016/j.envpol.2021.118451. ISSN 0269-7491. PMID 34740735. S2CID 242067709.
- ^ Transport and deposition of ocean-sourced microplastic particles by a North Atlantic hurricane Archived 5 May 2024 at the Wayback Machine, Anna C. Ryan et al, Nature (journal) - Communications Earth & Environment, 2023-11-23, accessed 2023-12-21
- ^ "Rifiuti diventano stato, Unesco riconosce 'Garbage Patch'" [Waste becomes state, Unesco recognizes 'Garbage Patch']. Archived from the original on 14 July 2014. Retrieved 3 November 2014.
- ^ www.theoceancleanup.com, The Ocean Cleanup. "www.theoceancleanup.com". The Ocean Cleanup. Archived from the original on 29 November 2020. Retrieved 19 April 2018.
External links
[edit]- "Sargasso Sea Commission". Archived from the original on 31 October 2015.
- Plastics at SEA: North Atlantic Expedition
- The Ocean Cleanup Array
North Atlantic garbage patch
View on GrokipediaDiscovery and Historical Context
Initial Observations and Documentation
The first scientific documentation of plastic debris accumulation in the North Atlantic Gyre was reported in 1972 by Edward J. Carpenter and K. L. Smith Jr. of the Woods Hole Oceanographic Institution, who sampled the surface waters of the Sargasso Sea.[15] Their neuston net tows revealed widespread plastic particles, with average concentrations of 3,500 pieces and 290 grams per square kilometer in the western Sargasso Sea.[16] These findings, published in Science, noted that the debris consisted mainly of small, brittle, pellet-shaped fragments, many industrially manufactured and resistant to degradation, distinguishing them from natural Sargassum accumulations.[15] Carpenter and Smith observed concentrations ranging from 50 to 12,000 particles per square kilometer, collectively weighing up to 1,070 grams, underscoring the gyre's circulatory currents as a mechanism for concentrating lightweight pollutants far from coastal sources.[3] The researchers warned of potential ecological threats, including ingestion by Sargasso Sea fauna and disruption of the surface microlayer ecosystem, based on the particles' persistence and distribution.[15] This study marked the earliest empirical evidence of anthropogenic plastic pollution forming diffuse patches in subtropical gyres, predating similar reports from the North Pacific by over two decades.[17] Subsequent early surveys in the 1970s and 1980s, including those by the same researchers, confirmed persistent plastic presence across broader gyre regions, with particle counts exceeding natural debris by orders of magnitude in some areas.[3] However, limited sampling technology at the time—relying on surface trawls and visual inspections—meant initial estimates focused on macro- and meso-plastics, underrepresenting microplastic contributions later quantified through advanced filtration.[18] These observations laid the groundwork for recognizing the North Atlantic Garbage Patch as a dynamic, low-density accumulation driven by wind and current convergence rather than a visible solid mass.[17]Evolution of Research Efforts
Initial observations of plastic debris in the North Atlantic Ocean date to 1972, when researchers Edward J. Carpenter and Kenneth L. Smith Jr. reported concentrations averaging 3,500 plastic particles per square kilometer on the surface of the western Sargasso Sea, a core region of the North Atlantic Subtropical Gyre. Their findings, based on neuston net tows, highlighted the widespread presence of small resin pellets and fragments, attributing them primarily to industrial sources rather than consumer litter, and noted potential risks to marine life through ingestion. Follow-up surveys in 1973–1974 expanded this to broader northwestern Atlantic waters, confirming plastic particles in over 90% of samples across a 1,000-kilometer transect, with densities up to 1,500 pieces per square kilometer.[19] Systematic long-term monitoring began in the mid-1980s through the Sea Education Association (SEA), which initiated routine surface trawling for plastic debris aboard research vessels starting in 1984, focusing on the western North Atlantic.[20] Between 1986 and 2008, SEA collected data from 6,136 neuston net tows across 6,100 locations, revealing that over 60% of samples contained plastic, with the highest concentrations—exceeding 100,000 particles per square kilometer—confined to the gyre's convergence zone. Analysis of this time series, published in 2010 by Kara L. Law and colleagues, demonstrated exponential growth in surface plastic abundance, rising from negligible levels in the 1960s to 5.5 trillion particles by 2008, driven by increased production and inputs rather than degradation dynamics alone. This work shifted research from sporadic sightings to quantitative trend assessment, emphasizing the gyre's role in retaining buoyant debris via Ekman convergence. Subsequent efforts incorporated numerical modeling to elucidate patch formation and persistence. In 2012, Erik van Sebille et al. used Lagrangian particle tracking simulations forced by ocean circulation data to predict garbage patch evolution, identifying the North Atlantic patch as one of six major accumulations worldwide, with retention times of 1–2 years for most debris before beaching or sinking.[21] Field expeditions followed, including the 2014–2015 7th Continent project, which sampled macro- and microplastics directly in the gyre, revealing biofilms and microbial communities on debris that facilitate hitchhiking species and potential degradation.[22] By the 2020s, research evolved toward ecological and remediation projections; for instance, 2020 GEOMAR expeditions traced debris pathways using drifters, while 2022 modeling by The Ocean Cleanup forecasted microplastic concentrations exceeding ecological thresholds without intervention, based on fragmentation rates from earlier SEA data.[23][12] These advances underscore a progression from descriptive surveys to integrated dynamical and biological analyses, prioritizing empirical validation over anecdotal reports.Physical Description
Location and Spatial Extent
The North Atlantic Garbage Patch is situated within the North Atlantic Subtropical Gyre, a clockwise-rotating system of ocean currents encompassing the region between approximately 22°N and 38°N latitude, extending offshore from the eastern United States coastline toward the mid-Atlantic.[24][25] This accumulation zone lies hundreds of kilometers from land, primarily between the latitudes of Cuba (around 23°N) and Virginia (around 37°N), with its eastern boundaries remaining imprecise due to limited sampling coverage in those areas.[24] Unlike a visible island of debris, the patch consists of a diffuse distribution of primarily microplastics and larger fragments concentrated by gyre convergence, spanning thousands of square kilometers but varying dynamically with currents and winds.[1] Data from surface net tows conducted between 1986 and 2008 indicate average plastic concentrations of about 4,000 pieces per square mile across the mapped extent, with localized peaks reaching 250,000 pieces per square mile in high-accumulation subregions.[24] The overall spatial footprint is smaller than the Great Pacific Garbage Patch, reflecting differences in gyre scale and debris influx, though exact areal measurements are challenging owing to the patch's heterogeneity and mobility.[26] The gyre's boundaries are defined by major currents—the Gulf Stream to the west, the Canary Current to the east, the North Atlantic Current to the north, and the North Equatorial Current to the south—trapping debris in a semi-enclosed vortex that prevents easy escape. Concentrations are highest near the gyre's center, where downwelling and convergence enhance retention, but the patch extends vertically from the surface into subsurface layers and sporadically to the seafloor in some areas.[1] Ongoing monitoring reveals no significant expansion in surface concentrations over the studied period, potentially due to fragmentation, sinking, or biofouling rather than dispersal.[24]Composition, Density, and Dynamics
The North Atlantic Garbage Patch consists predominantly of synthetic plastic debris, including macroplastics such as fishing nets, ropes, and buoys, alongside microplastics derived from their fragmentation. Common polymer types include polyethylene (PE), polypropylene (PP), and polystyrene (PS), which account for the majority of buoyant debris due to their low density relative to seawater.[5] Thin plastic films, monofilament lines, and fragments dominate the macroplastic fraction, with fishing gear contributing substantially as durable, long-lasting items that resist rapid breakdown. Microplastics, typically under 5 mm, form through mechanical abrasion by waves and photo-oxidative degradation from ultraviolet exposure, leading to a shift from larger to smaller particle sizes over time.[27] Densities of plastic debris in the patch vary spatially but are highest within the central convergence zone of the North Atlantic Subtropical Gyre, with surface concentrations reaching maxima exceeding 10^6 pieces per km² for particles larger than 0.5 mm.[28] Mean mass concentrations approximate 600 g per km² in accumulation areas, though numerical abundances can range from 50 to 12,000 particles per km², with total weights up to 1,070 g per km². In the upper water column, microplastic densities average around 50 × 10^6 pieces per km² integrated over depths to 1,150 m, decreasing rapidly below the surface from approximately 1 item per m³ to 0.001–0.01 items per m³ within the top few meters.[29][30] These levels in the gyre core often surpass thresholds deemed safe for marine organisms, based on ingestion risk models.[12] Dynamics of the patch are driven by the anticyclonic circulation of the North Atlantic Subtropical Gyre, where Ekman convergence from wind-forced surface currents traps and concentrates buoyant plastics in subtropical latitudes around 25–35°N. Debris circulates within the gyre for years to decades, with limited export due to retention by the Azores Current and Gulf Stream boundaries, though seasonal winds and storms can induce vertical mixing or temporary dispersion.[27] Degradation processes, including UV-induced fragmentation and biofouling, progressively reduce particle size and buoyancy, facilitating subduction into subsurface layers or sinking upon density changes from attached organisms or calcite encrustation.[31] Overall, the patch exhibits quasi-stable accumulation rather than a solid mass, with concentrations correlating inversely with distance from the gyre center and showing temporal stability over multi-year sampling from 1986 to 2008.[32]Sources and Pathways
Primary Material Origins
The primary materials comprising the North Atlantic Garbage Patch are predominantly plastic polymers, including polyethylene (PE), polypropylene (PP), and polyamide (nylon), which form durable fragments such as films, lines, nets, and pellets.[27] These materials originate from anthropogenic waste, with global estimates attributing approximately 80% of marine plastic inputs to land-based sources and 20% to ocean-based sources.[33][34] Land-based contributions stem from mismanaged solid waste in coastal populations, including packaging, bottles, and consumer goods discarded via rivers, stormwater runoff, and direct beach littering; major pathways include rivers draining densely populated regions around the North Atlantic basin, such as those in Europe and the eastern United States.[17] Industrial and agricultural activities exacerbate this through wastewater discharges containing plastic microbeads and fibers.[17] Ocean-based sources, while comprising a smaller overall fraction of inputs, disproportionately contribute to the persistent floating macrodebris (>5 mm) that accumulates in the gyre due to its buoyancy and resistance to degradation. Discarded fishing gear—nets, ropes, and buoys—from industrial fleets represents the dominant category, with peer-reviewed analyses indicating that fishing activities account for the majority of such floating macroplastics across oceanic gyres, including the North Atlantic Subtropical Gyre.[34] Shipping-related waste, such as lost cargo containers and operational discharges, adds to this, though to a lesser extent; for instance, studies of debris composition in the gyre reveal high proportions of synthetic lines and sheets traceable to maritime operations.[35] This sea-sourced material persists longer in surface waters compared to many land-derived items, which fragment into sinking microplastics or adsorb to sediments more rapidly.[34] Regional specificities influence source profiles: debris in the North Atlantic often includes items from North American and European fisheries, supplemented by transatlantic transport of lighter plastics from distant land sources, though direct offshore origins prevail for macro-accumulations. Empirical modeling and isotopic tracing confirm that while initial inputs are diffuse, gyre dynamics concentrate these materials regardless of proximal origins, underscoring the need to address both terrestrial waste management and maritime practices for mitigation.[34][35]Transport Mechanisms into the Gyre
Plastic debris enters the North Atlantic Subtropical Gyre predominantly from land-based sources, which account for approximately 80% of marine litter inputs, via rivers, coastal runoff, wind-blown litter, and wastewater discharges.[36] Mismanaged plastic waste from households, industries, and urban areas constitutes the primary material, with global estimates of 4.8 to 12.7 million metric tons entering oceans annually, a portion of which reaches the Atlantic via proximate continents.[36] [17] Riverine transport serves as a dominant pathway, conveying debris from inland pollution hotspots to coastal waters, where North American rivers like the Mississippi and European systems such as the Rhine contribute significantly due to high population densities and plastic usage in their drainage basins.[17] Maritime activities supplement these inputs, including abandoned or lost fishing gear, which forms a substantial fraction of larger floating debris, alongside discards from shipping containers and vessels.[1] [37] In the ocean, surface currents dominate long-range transport, with the Gulf Stream carrying western Atlantic coastal effluents northeastward and the Canary Current directing eastern inputs westward, funneling debris into the gyre's convergence zone near the Sargasso Sea.[17] Wind-driven Ekman transport, induced by the persistent Azores High pressure system, and wave-induced Stokes drift propel surface particles inward, enhancing accumulation through convergent circulation patterns modeled in global ocean simulations.[36] These mechanisms result in retention times of years to decades within the gyre, as evidenced by particle tracking models incorporating diffusion and decay processes.[36]Scientific Research and Measurement
Methodologies and Key Studies
Methodologies for quantifying plastic debris in the North Atlantic Garbage Patch primarily rely on surface-level sampling via neuston trawls equipped with 0.3–0.335 mm mesh nets, such as Manta or WP-2 designs, towed at speeds of 1–3 knots to collect floating microplastics greater than approximately 300 μm. Samples undergo density-based separation using saline solutions, followed by microscopic identification and confirmation through Fourier-transform infrared (FTIR) or Raman spectroscopy to differentiate synthetic polymers from natural particulates.[28] These approaches, while effective for larger microplastics, underestimate mega- and macro-debris due to their sparsity and vertical distribution, and they risk contamination from airborne fibers unless rigorous cleanroom protocols are enforced.[27] For subsurface and finer fractions, including nanoplastics under 1 μm, researchers employ in-water pumping systems or Niskin bottle arrays from conductivity-temperature-depth (CTD) rosettes, filtering large volumes (up to thousands of liters) onto 0.2–1 μm pore-size membranes for subsequent scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy or pyrolysis-gas chromatography-mass spectrometry.[38] Vertical fluxes are measured using drifting sediment traps deployed at depths from 50 m to 600 m, capturing sinking particles over periods of days to weeks.[10] Numerical modeling complements field data through Lagrangian particle-tracking simulations driven by high-resolution ocean circulation models like HYCOM or GLORYS, incorporating windage and biofouling parameters to forecast accumulation in convergence zones.[21] A foundational study by Law et al. (2010) compiled 6,136 neuston net samples from Sea Education Association voyages spanning 1986 to 2008, revealing that 83% of encountered plastic mass concentrated within the gyre's core, with peak densities of 5.1 × 10^4 particles km⁻² and 5.7 × 10^3 g km⁻², yet no statistically significant rise in gyre concentrations over time, indicating potential saturation or export via sinking and beaching. Zettler et al. (2017) sampled diverse polymer types directly from the gyre using boat-based collection, applying 16S rRNA metagenomic sequencing to characterize microbial assemblages, which exhibited metabolically distinct communities adapted to plastic surfaces compared to ambient seawater. More recent efforts include Koelmans et al. (2022), who deployed moored and drifting traps to quantify microplastic export rates, finding downward fluxes increasing with depth and dominated by fibers, suggesting rapid removal from surface layers via aggregation and ballast.[10] A 2025 investigation by Meijer et al. reported nanoplastic abundances 1.8 times higher in gyre intermediate waters (around 200–500 m) than in surrounding regions, derived from filtered water column profiles and particle sizing, estimating totals exceeding 27 million metric tons in the upper North Atlantic—though critics argue methodological artifacts, such as incomplete polymer verification and potential lab contamination, may inflate these figures beyond empirical bounds.[38][39] Longitudinal transects, as in Gove et al. (2022), integrated pump and trawl data across the gyre, confirming composition skewed toward polyethylene and polypropylene fragments, with abundances declining eastward from the Sargasso Sea core.[27]Recent Findings and Projections
A 2025 study published in Nature quantified nanoplastic concentrations across the North Atlantic, revealing that the subtropical gyre harbors significantly elevated levels at intermediate depths, with 13.5 mg m⁻³ at 1,000 m—1.8 times higher than in open ocean areas outside the gyre.[38] In the gyre's mixed layer (10 m depth), concentrations averaged 15.1 mg m⁻³, dominated by polyethylene terephthalate (PET), polystyrene (PS), and polyvinyl chloride (PVC), while coastal stations showed even higher levels at 25.0 mg m⁻³.[38] The research estimated 15.2 million metric tons of nanoplastics in the gyre's mixed layer alone, dwarfing prior models of macro- and microplastic mass (0.31 million metric tons) and indicating that nanoplastics constitute the predominant form of plastic pollution by mass.[38] Expeditions in the North Atlantic subtropical gyre, including a 2020 survey analyzed in subsequent modeling, found small microplastics (<100 μm) up to 10 million times more abundant than larger fragments (>500 μm) in the upper 300 m water column.[12] These concentrations already approach safe thresholds for pelagic species, as defined by ingestion risk models, with plankton in the gyre exposed at higher rates than in coastal zones due to vertical mixing and fragmentation.[12][30] Projections indicate that without removal interventions, microplastic densities in the gyre will surpass ecological safe limits in the near term, as floating debris continues fragmenting into sinking micro- and nanoplastics that accumulate vertically.[12] Global analyses of microplastic trends suggest particle densities have roughly doubled per decade since the 1980s, with regional gyre variations potentially accelerating this in the North Atlantic due to persistent inputs and poor degradation.[40] Updated ocean plastic budgets must account for nanoplastics to refine these forecasts, as their underestimation previously masked the true scale of accumulation.[38]Environmental Impacts
Direct Effects on Marine Ecosystems
Plastic debris in the North Atlantic Garbage Patch directly harms marine ecosystems through ingestion and entanglement, leading to immediate physical injuries, physiological disruptions, and mortality among affected organisms. Marine species, including fish, seabirds, and mammals, frequently mistake floating macroplastics and microplastics for prey, resulting in gastrointestinal blockages that cause starvation and internal lacerations.[8] In the North Atlantic Subtropical Gyre, surface plastic concentrations averaged 0.020 particles per square meter between 1986 and 2008, with over 60% of sampled net tows containing detectable debris, facilitating widespread exposure.[32] [8] Ingestion impacts are evident across trophic levels, particularly in planktivorous and mesopelagic fish, where microplastics—often less than 5 mm in size—have been found in 11% of specimens from the Northeast Atlantic, predominantly black or blue fragments in digestive tracts.[41] Seabirds such as northern fulmars and great shearwaters in the North Atlantic exhibit high ingestion rates, with 70-95% of great shearwaters containing plastics, leading to reduced stomach capacity, false satiation, and impaired reproduction.[42] [43] These effects extend to sub-lethal outcomes like decreased feeding efficiency and growth, disrupting energy allocation and population dynamics.[8] Entanglement primarily arises from derelict fishing gear and larger debris concentrated in the gyre, posing acute risks to mobile species by constricting movement, causing wounds, and inducing drowning.[44] In the North Atlantic Gyre, certain marine species face elevated entanglement probabilities due to the prevalence of abandoned lines and nets, which can immobilize individuals and exacerbate injury through tissue damage and infection.[44] [8] While ingestion affects a broader array of smaller organisms, entanglement disproportionately threatens larger predators, altering predator-prey balances within the ecosystem.[45]Evidence of Broader Ecological Harm
Microplastics originating from the North Atlantic garbage patch ingress the marine food web primarily through ingestion by mesopelagic fish, with surveys of species such as Cyclothone spp. and Benthosema spp. revealing occurrence rates of 11.0% in digestive tracts sampled between 2006 and 2009.[41] This trophic transfer extends to planktivorous fish regurgitated by seabirds, where concentrations peak seasonally—reaching higher levels in December—and amplify exposure risks for predators.[46] Seabirds in regions adjacent to the gyre, including Arctic populations, exhibit microbiome alterations from environmentally realistic microplastic mixtures, with laboratory exposures mirroring field conditions and correlating to shifts in microbial diversity that may impair digestion and immune function.[47] Concurrently, microplastics sorb persistent organic pollutants and additives like phthalates, which co-occur in seabird tissues and facilitate bioaccumulation, exacerbating sublethal effects such as endocrine disruption observed in controlled studies on species like northern fulmars.[48][49] Beyond pelagic systems, gyre-derived debris contributes to coastal biodiversity declines through beaching and habitat smothering, with Atlantic island surveys documenting elevated microplastic loads in sediments that correlate with reduced infaunal diversity and impaired ecosystem services like nutrient cycling.[50] Plastic-associated biofilms, or plastispheres, further propagate non-native microbial communities, potentially vectoring pathogens and altering biogeochemical processes across open-ocean to shoreline gradients.[51] These mechanisms underscore cascading harms, including fishery-relevant species' compromised foraging efficiency and elevated contaminant burdens that propagate to apex consumers.[52]Controversies and Skeptical Perspectives
Exaggerations in Scale and Visibility
Media portrayals of the North Atlantic garbage patch frequently depict it as a massive, contiguous expanse of visible debris akin to a floating landfill, comparable in scale to entire countries or states. These representations, often amplified in documentaries and news reports, imply a solid, easily observable mass spanning millions of square kilometers. However, such imagery grossly misrepresents the actual nature of the accumulation, which consists predominantly of microplastics and fragmented debris dispersed at low densities across the North Atlantic Subtropical Gyre.[53] [24] Scientific surveys, including those conducted by the 5 Gyres Institute in 2010, reveal that the patch's debris is invisible to satellite imagery due to its diffuse distribution, with plastic concentrations rarely exceeding a few kilograms per square kilometer—far too sparse to form detectable surface features from orbit or even low-altitude aircraft. On-site observations from research vessels confirm that, except under unusually calm conditions, the plastics are not readily apparent from deck level, appearing more as a subtle "soup" interspersed with plankton and organic matter rather than clustered rafts of bottles or nets. This low visibility persists despite the gyre's vast area, estimated at around 2 million square kilometers for elevated plastic zones, where "size" metrics denote the spatial extent of above-background concentrations, not uniform coverage or tangible volume.[24] [53] Exaggerations in scale often arise from extrapolating early anecdotal reports or conflating the gyre's total area with debris volume; for instance, parallels to the Pacific patch's debunked "twice the size of Texas" claims highlight how area-based figures mislead by suggesting solidity, when in reality, the Atlantic accumulation equates to roughly 5.5 trillion plastic pieces totaling under 10,000 metric tons—equivalent to a single large city's annual waste output diluted over an ocean basin. Peer-reviewed analyses emphasize that these distortions can overshadow the genuine threat of persistent microplastics, which evade casual detection but bioaccumulate in food webs, while advocacy-driven visuals prioritize alarm over precision.[54] [55]Debates on Actual Toxicity and Adaptations
While plastics in the North Atlantic garbage patch can physically harm marine organisms through ingestion and entanglement, leading to reduced feeding efficiency and internal blockages in species like sea turtles and seabirds, the chemical toxicity of the debris itself remains debated, with many polymers considered chemically inert in seawater under ambient conditions.[56]30140-7/fulltext) Critics argue that direct toxicity primarily stems from additives such as phthalates or heavy metals like lead and cadmium, or from persistent organic pollutants (POPs) such as PCBs and DDT that adsorb onto plastic surfaces, but empirical field data on bioaccumulation and population-level impacts in the gyre are limited, with laboratory studies often exaggerating effects due to unrealistically high exposures.[57] A review of microplastic toxicity highlights that while over 100 marine species show uptake, causal links to widespread mortality or reproductive failure in natural gyre concentrations—typically microplastics at parts-per-billion levels—are inconclusive, prompting skepticism that the narrative of acute chemical poisoning overshadows physical and ecological disruptions.[58][59] Proponents of heightened concern cite potential for microplastic fragmentation to release monomers or facilitate pathogen transfer via biofouling, yet counterarguments emphasize that ocean dilution and photodegradation reduce leaching rates, with no verified mass die-offs attributable solely to plastic-derived toxins in the North Atlantic gyre as of 2023 surveys.30140-7/fulltext) Materials scientists like Chris DeArmitt have contended that plastics' environmental persistence does not equate to inherent toxicity, attributing much alarm to unproven transfer of harms to human food chains via seafood, where detected microplastic levels fall below regulatory thresholds for additives.[60] This perspective aligns with analyses questioning whether microplastics warrant the "toxic crisis" framing, given sparse evidence of endocrine disruption or carcinogenesis in wild populations compared to natural stressors like UV radiation or predation.[59] Regarding adaptations, marine organisms in the gyre have demonstrated colonization of floating plastics as novel substrates, enabling rafting and reproduction for coastal invertebrates such as barnacles, mussels, and crabs, which attach and thrive on debris, potentially expanding their geographic ranges beyond natural limits.[61][62] Studies from the eastern North Pacific gyre, analogous to North Atlantic conditions, identified 37 taxa reproducing on plastics, suggesting an ecological niche where debris acts as artificial islands fostering biodiversity in oligotrophic waters, though this may disrupt native pelagic communities.[61] Microbial biofilms on plastics, including non-marine bacteria, further indicate adaptive degradation processes, with some strains evolving to metabolize polyethylene, potentially mitigating long-term accumulation but raising questions about altered carbon cycling.[51] Debates persist on whether these adaptations represent resilience or maladaptation, as reliance on unstable plastic rafts could expose colonizers to higher UV or predation risks, yet field observations show no immediate collapse of such assemblages.[63]- Key adaptations observed:
- Habitat provision: Plastics support sessile species like bryozoans and hydroids, absent on natural flotsam due to faster sinking.[61]
- Microbial bioremediation: Plastic-associated bacteria exhibit hydrocarbon-degrading enzymes, accelerating breakdown in sunlit gyre zones.[51]
- Dispersal benefits: Rafting facilitates gene flow for species like the veined rapa whelk, though invasive potential in recipient ecosystems is unquantified.[62]
