Table 1.

Recent studies reported the concentration of MPs in different seas

Study area	Dominant debris type	Polymers	Concentration (particles/kg DW)	Explanations	References
Andaman Sea	Fibers	Acrylic, PE, Nylon, and PEP	15.36	Increased anthropogenic activities and uncontrolled plastic disposal along the coastline, semi-treated/non-treated urban effluent discharge increased the pressure of MPs Amplified shipping and fishing activities triggered the fibrous MPs in the Andaman region	Goswami et al. (2021)
Andaman Sea	Fragment and pellet	Nylon, acrylic, and ionomer	45.17	-	Goswami et al. (2020)
Arabian Sea	Fibers	Acrylic, PE, Nylon, and PEP	128.02	Mixing of low-saline Bay of Bengal water into the Arabian Sea that could transport floating MPs from the coastal areas Abundance of laundry wastes with a great amount of acrylic fabric and increased fishing and shipping industry that added the large number of synthetic fibers in the Arabic Sea	Goswami et al. (2021)
Arabian Sea (Coast)	Fragmented	PE and PP	664	Increased industrial and urban activities near the coastline Mechanical and oxidative weathering of large plastic particles	Yaranal et al. (2021)
Arctic Sea	Fragment	PE, PP, and PA	42–6595	Thermohaline circulation of MP debris from Northern Europe to the North and melting of sea ice released the MPs in the Arctic Sea Excessive use of PP and PE in packaging materials and fishing gears increased their amount in the Europe region	Bergmann et al. (2017)
Baltic Sea	Fibers	-	34	Mixing of discharge released from wastewater	Zobkov and Esiukova (2017)
Baltic Sea	Fibrous	PE, PP, PET, PDMS, PVC	863	The oceanographic factors like sediment fraction, surface wave current, and water column structure (i.e., density of MPs jumps at the thermocline and pycnocline levels) are responsible for mixing of MPs Fiber distribution in bottom deposits depends on erosion/transition/accumulation zones	Chubarenko et al. (2022)
North Sea	Fibers		65.95	The geometry of this location regardless of any other area is very unique. Here, the flushing rate is comparatively very low and the narrow entrance can cause the incidence of tidal eddies. The MP floating into such areas gets trapped in the vortex and settles down on the bottom of the seafloor	Claessens et al. (2011)
Black Sea	Fibers	PE and PP	106.7	The storms and wind imply the surface mixing and redistribution of MPs in the water column and sea bed Occurrence of polyamide fibers is related to maritime usages, such as fishing activities	Cincinelli et al. (2021)
Black Sea	Fibers	PE and PP	98	Fluvial transport of MPs from poorly treated wastewater or inadequately treated sewage sludge in Black sea	Pojar et al. (2021)
Bohai Sea	Fibers	PEVA, LDPE, and PS	102.9–163.3	The semi-closed geographical structure surrounded by densely packed industrial and urban structures is responsible for MPs load in this sea	Yu et al. (2016)
Bohai Sea	Fibers and fragments	Rayon, PET, CP, PA, PE, PP, and PC	137	The weak hydrodynamic force favors the settling of fine particulate matter and fine sediment, which is suitable for the deposition of small-sized MPs in the bottom of the sea	Zhang et al. (2022)
Caribbean Sea	Fibers	-	261	The tourism and population near the shoreline promoted the MP pollution	Bosker et al. (2018)
Caribbean Sea	Fragments	-	1109	Flourished human activities along the coastal line, especially the generation of high amounts of single-use plastics.	Rangel-Buitrago et al. (2021)
Caspian Sea	Fibers	PS and PET	196.67	Influx of rivers, Gorganrud, Nokandeh, and Qarasu, promotes the entry of MPs into the sea The anti-clockwise circulation of water from the westerns part to the eastern of the southern Caspian Sea is responsible for transfer of MPs	Manbohi et al. (2021b)
Chukchi Sea	Fibers	PP, PET, and rayon	31.6	In the course of melting process entrained in Arctic Sea ice, released MPs enhanced their number in the Chukchi Sea	Mu et al. (2019)
Da Nang Coast	Synthetic fiber	PA, PVOH, Polyester, PET, PAN, and PAK	9283	Man-made activities such as the discharge of industrial wastewater, solid waste, and landfill leachate have increased the MPs number in this area	Tran Nguyen et al. (2020)
Eastern Baltic Sea	Fibers and fragments	-	490	The discharge and buoyant particles from various basins accumulate in this region Secondly, the cyclonic current arrangement of this area promotes the recirculation of surface water in the basin for the mean cyclonic current structure of the BP recirculates/traps the surface water in the basin for a lengthier period of time, which supports the settlement of MPs on the sea floor	Mishra et al. (2022)
Great Australian Bight	Fragments	Polyisoprene (rubber/latex), PU, polyester, and PP	13.6	The seafloor slope angle and MPs abundance are correlated with each, i.e., area having a steep slope seafloor angle also having a high MP number and vice-versa	Barrett et al. (2020)
North Yellow Sea (Qingduizi Bay)	Fibers	PET and CP	33.15	Geographically, this area is semi-closed; thus, an exchange of external water is relatively low that favored the accumulation of MPs	Chen et al. (2022a)
Red Sea	Fragments	PE	1–160	The amplified number of MPs in the Red Sea is either linked with industrial areas or densely populated zones. Lack of recycling infrastructure also promotes the growth of MPs here	Ruiz-Compean et al. (2017)
Red Sea	Fibers and granules	PP and HDPE	nd–119	The intense solar radiation and high temperature of Saudi coastal area enhance the degradation of plastic materials into micro/nanosized plastic materials	Al-Lihaibi et al. (2019)
South Africa Coasts	Fibers	-	80–87	Especially, the mixing of Mzimvubu and Tugela rivers into the South African coasts has elevated the microfiber load in sediment, because most of the part of river basins suffered from the influx of wastewater treatment plant discharge	De Villiers (2018)
Southern Baltic Sea	Fibers and fragments	PP, PE, PS	76–295	Population density and coastal development are the major sources of MPs	Urban-Malinga et al. (2020)
Southern Black Sea	Fragments	PE and PET	181–944	The distribution of MPs in the Southern Black Sea is governed by the interactions between wind and oceanographic topographies such as fronts and eddies that craft an area for MP deposition	Eryaşar et al. (2021)
Southern Caspian Sea	Films and fibers	PE, PP, and PET	246	Influx of local rivers and hydrodynamics along with activities like fishing and industrial discharge are the predominant sources of MPs in the Southern Caspian Sea	Manbohi et al. (2021a)
South China Sea	Granular	Polyester, Rayon, and Nylon	7705	The influence of river discharge and coastal activities is the major source of MPs in this area	Cui et al. (2022)
Southern North Sea	Spheres and fibers	PP, acrylates, PU, and PA	2.8–1188.8	The fine sediment texture of North Sea is responsible for the abundance of MPs. Moreover, incorporation of buoyant MPs into clusters can be another reason for occurrence of MPs the benthic boundary layer	Lorenz et al. (2019)
Tokyo Bay	Fibers and beads	PEP, PE, PAK, PP, PVC, and PCL	1845–5385	Because of the input of high levels of MPs into the canal and the degree of their sedimentation is relatively very high (2–3.5 cm/year) that stocks the MPs in Tokyo Bay	Matsuguma et al. (2017)
Tyrrhenian Sea	Filaments, fragments, and films	Nylon, PU, PE, and PET	1.70	The Tyrrhenian Sea is well known for its high maritime traffic because this Sea provides a route for connection between Elba island and mainland. The load of MPs along the shipping routes is very high because of the use of epoxies, nylon ropes, nets, etc., in ferries that strike the load of MPs here	Mistri et al. (2020)
Indian Coastline	Fibers and fragments	PE, PP, and PET	12.22–439	Because the huge production of solid waste (around 62MT, collected ~82%) in India, of which only 28% can be treated and the rest is dumped in open areas is the major source of MPs Furthermore, unique oceanic dynamics and monsoon patterns can be another reason for high level of MPs on the Indian Coastline	Ranjani et al. (2021)

PP polypropylene, PE polyethylene, PS polystyrene, PET polyethylene terephthalate, PDMS polydimethylsiloxane, PVC polyvinyl chloride, CP cellophane, PA polyamide, PC polycarbonate, PEP polyethylene-polypropylene co-polymers, PU polyurethane, PVOH poly-ethylene vinyl alcohol copolymers, PAN polyacrylonitrile, PAK polyacrylate, PCL polycaprolactone, PEVA polyethylene vinyl acetate, LDPE light density polyethylene, MT metric tonnes, PMMA polymethylmethacrylate