二次塑料是由較大的塑料廢棄物分解而成的小片塑料。在時間演進之中,歷經物理、生物和化學光降解(包括由陽光照射引起的光氧化(英語:Photo-oxidation of polymers)),這些碎片的結構最終降低到肉眼無法察覺到的大小。 [30]這種過程稱為破碎化(fragmentation)。[28]微塑料被認為會再進一步降解成尺寸更小的程度,但據報導,目前在海洋中檢測到最小微塑料的直徑為1.6微米(6.3×10−5英寸)。[31]破碎化持續進行是導致各處普遍均有各式形狀微塑料的原因。 [14]據觀察,無論在海水或是淡水中,由可生物降解聚合物所形成的微塑料數目,遠高於由不可生物降解聚合物所形成的。[32]
航運是造成海洋污染的重要原因。一些統計數據顯示在1970年,世界各地的商業船隊向海洋環境傾棄超過23,000噸塑料垃圾。在1988年簽訂的《防止船舶污染國際公約(MARPOL 73/78,附 V)禁止船舶把廢棄物傾倒進入海洋環境。美國在1987年通過的海洋塑料污染研究和控制法案( Marine Plastic Pollution Research and Control Act of 1987)禁止船舶(包括海軍艦艇)在海中排放塑料。 [72][73]但航運業仍是塑料污染的主要來源,在1990年代初期即傾棄約650萬噸塑料進入海洋。[74][75]研究顯示在夏威夷海灘上發現的塑料中約有10%是塑料顆粒。[76]在2012年7月24日,香港經歷一場大風暴後,有150噸塑料顆粒和其他塑料原料從附近海岸的船上溢出。據報導,這批來自中國石化公司的塑膠廢棄物大量堆積在海灘上。[34]這事件是一起大型洩漏事件,研究人員推測還有更小的事故發生,而進一步加劇海洋微塑料污染。[34]
2008年在華盛頓大學塔科馬校區舉行名為微塑料海洋垃圾的發生、影響和歸宿國際研究研討會(International Research Workshop on the Occurrence, Effects and Fate of Microplastic Marine Debris),參與者[97]的結論認為微塑料是海洋環境中的一個問題,原因為:
研究人員凱利等人(Kelly et al)在2009年從南極洲東部取樣的冰芯中發現有96種微塑料顆粒,屬於14種不同的聚合物 。[153]在此之前,南極洲的地表水和沈積物以及北極海冰中都有塑料污染的記錄,但這次被認為是首次在南極海冰中發現有塑料污染。這些相對較大的顆粒顯示是來自當地的局部污染源。[153]
此外,某些微生物(參見塑料生物圈(英語:plastisphere)#Degradation by microorganisms)已適應食用塑料,一些細菌物種經過基因改造後可食用某些類型的塑料。 [179]微生物除用於降解微塑料外,還可從受污染的樣品中捕獲其上的生物薄膜基質中的微塑料,以更容易的方式去除此類污染物。[180]還有生物薄膜中的微塑料可利用加工後的「釋放」機制,從薄膜擴散而釋放,促進微塑料的回收。[181]
隨著人們越來越警覺到微塑料對環境的不利影響,相關團體也提倡從各種產品中去除和禁用微塑料。[191]其中一項活動是「打敗柔珠」,重點是從個人護理用品中去除塑料。[61]倡議組織Adventurers and Scientists for Conservation開展全球微塑料倡議,目的為收集水樣,提供更好的證據給科學家,以了解微塑料在環境中擴散的的狀況。[192]UNESCO贊助研究和進行全球評估計劃,以處理會跨境影響的微塑料問題。[193]這些環保組織將持續向製造商施壓,要求他們從產品中去除塑料,以維持健康的生態系統。[194]
歐盟執行委員會已注意到人們越來越關注微塑料對環境的影響。[204]2018年4月,歐盟委員會的首席科學顧問小組通過歐盟的科學建議機制委託,對微塑料污染的科學證據進行全面審查。[204]審查由歐洲學術機構提名的工作組進行,並於2019年1月交付結果。[205]一份基於SAPEA報告(SCIENCE ADVICE FOR POLICY
BY EUROPEAN ACADEMIES Report)的科學意見向執行委員會提出,委員會將根據資料決定是否應在歐盟層面上提出政策變化,以遏制微塑料污染。 [206]
執行委員會的循環經濟行動計劃對關鍵產品(即塑料包裝)的回收和減廢提出強制性要求。行動計劃啟動限制在產品中添加微塑料。規定在產品生命週期各階段捕獲更多微塑料的措施。例如該計劃將審查目的在減少輪胎和紡織品釋放二次微塑料的各項政策。[208]委員會計劃更新《城市污水處理指令(英語:Urban Waste Water Treatment Directive)》,以進一步解決微塑料廢棄物和其他污染問題,用以保護環境,免受工業和城市廢水排放之害。又臨時批准對歐盟飲用水指令的修訂,以確保定期監測飲用水中的微塑料。如果發現問題,指令要求各國必須提出解決方案。[10]
Klein S, Dimzon IK, Eubeler J, Knepper TP. Analysis, Occurrence, and Degradation of Microplastics in the Aqueous Environment.. Wagner M, Lambert S (編). Freshwater Microplastics. The Handbook of Environmental Chemistry 58. Cham.: Springer. 2018: 51–67. ISBN 978-3319616148. doi:10.1007/978-3-319-61615-5_3. See Section 3, "Environmental Degradation of Synthetic Polymers".
Leslie, Heather A.; van Velzena, Martin J.M.; Brandsmaa, Sicco H.; Vethaakab, A. Dick; Garcia-Vallejoc, Juan J.; Lamoree, Maria H. Discovery and quantification of plastic particle pollution in human blood. Environment International. 2022, 1 (3): 117. ISSN 0160-4120. PMID 35367073. S2CID 247688966. doi:10.1016/j.envint.2022.107199.
There is not yet a consensus on this upper limit.
Pinto da Costa, João. Nanoplastics in the Environment. Harrison, Roy M.; Hester, Ron E. (編). Plastics and the Environment. Issues in Environmental Science and Technology 47. London: Royal Society of Chemistry. 2018: 85 [2019-08-24]. ISBN 978-1788012416. (原始內容存檔於2020-08-05). First, it is necessary to define what constitutes a 'nanoplastic'. Nonoparticles exhibit specific properties that differ from their bulk counterparts and are generally considered as particles with less than 100nm in at least one dimension. [...] However, for nanoplastics, a clear consensus classification has not been reached and multiple size-based definitions have been proposed. [...] although nanoplastics are the least known type of plastic waste, they are also, potentially, the most hazardous. [...] Nanoplastics may occur in the environment as a result of their direct release or from the fragmentation of larger particles. They may, similarly to microplastics, [...] therefore be classified as either primary or secondary nanoplastics.
Ivar do Sul, Juliana A.; Costa, Monica F. The present and future of microplastic pollution in the marine environment. Environmental Pollution. 2014, 185: 352–364. PMID 24275078. doi:10.1016/j.envpol.2013.10.036.
Burghardt, Tomasz E.; Pashkevich, Anton; Babić, Darko; Mosböck, Harald; Babić, Dario; Żakowska, Lidia. Microplastics and road markings: the role of glass beads and loss estimation. Transportation Research Part D: Transport and Environment. 2022-01-01, 102: 103123. S2CID 244808286. doi:10.1016/j.trd.2021.103123.
Verschoor, A., van Herwijnen, R., Posthuma, C., Klesse, K., Werner, S., 2017. Assessment document of land-based inputs of microplastics in the marine environment. Publication 705/2017. OSPAR Commission: London, United Kingdom.
Periyasamy, Aravin Prince; Tehrani-Bagha, Ali. A review of microplastic emission from textile materials and its reduction techniques. Polymer Degradation and Stability. 2022-03, 199: 109901. doi:10.1016/j.polymdegradstab.2022.109901.
Napper, Imogen E.; Thompson, Richard C. Release of synthetic microplastic plastic fibres from domestic washing machines: Effects of fabric type and washing conditions. Marine Pollution Bulletin. 2016, 112 (1–2): 39–45. PMID 27686821. doi:10.1016/j.marpolbul.2016.09.025. hdl:10026.1/8163.
Fendall, Lisa S.; Sewell, Mary A. Contributing to marine pollution by washing your face: Microplastics in facial cleansers. Marine Pollution Bulletin. 2009, 58 (8): 1225–1228. PMID 19481226. doi:10.1016/j.marpolbul.2009.04.025.
Rochman, Chelsea M.; Kross, Sara M.; Armstrong, Jonathan B.; Bogan, Michael T.; Darling, Emily S.; Green, Stephanie J.; Smyth, Ashley R.; Veríssimo, Diogo. Scientific Evidence Supports a Ban on Microbeads. Environmental Science & Technology. 2015, 49 (18): 10759–10761. Bibcode:2015EnST...4910759R. PMID 26334581. doi:10.1021/acs.est.5b03909.
Tikhomirov, Iu P. Vliianie vybrosov proizvodstv akrilatov na okruzhaiushchuiu sredu i profilaktika ikh neblagopriiatnogo vozdeĭstviia [Effect of acrylate industry wastes on the environment and the prevention of their harmful action]. Vestnik Akademii Meditsinskikh Nauk SSSR. 1991, (2): 21–25. OCLC 120600446. PMID 1828644(俄語).
Derraik, José G.B. The pollution of the marine environment by plastic debris: a review. Marine Pollution Bulletin. 2002, 44 (99): 842–852. PMID 12405208. doi:10.1016/S0025-326X(02)00220-5. In the USA, for instance, the Marine Plastics Pollution Research and Control Act of 1987 not only adopted Annex V, but also extended its application to US Navy vessels
Craig S. Alig; Larry Koss; Tom Scarano; Fred Chitty. Control of Plastic Wastes Aboard Naval Ships at Sea(PDF). National Oceanic and Atmospheric Administration. ProceedingsoftheSecondInternational Conference on Marine Debris, 2–7 April 1989, Honolulu, Hawaii. 1990 [2018-12-20]. (原始內容存檔(PDF)於2017-01-25). The U.S. Navy is taking a proactive approach to comply with the prohibition on the at-sea discharge of plastics mandated by the Marine Plastic Pollution Research and Control Act of 1987
Teuten, E. L.; Saquing, J. M.; Knappe, D. R. U.; Barlaz, M. A.; Jonsson, S.; Bjorn, A.; Rowland, S. J.; Thompson, R. C.; Galloway, T. S.; Yamashita, R.; Ochi, D.; Watanuki, Y.; Moore, C.; Viet, P. H.; Tana, T. S.; Prudente, M.; Boonyatumanond, R.; Zakaria, M. P.; Akkhavong, K.; Ogata, Y.; Hirai, H.; Iwasa, S.; Mizukawa, K.; Hagino, Y.; Imamura, A.; Saha, M.; Takada, H. Transport and release of chemicals from plastics to the environment and to wildlife. Philosophical Transactions of the Royal Society B: Biological Sciences. 2009, 364 (1526): 2027–2045. PMC 2873017. PMID 19528054. doi:10.1098/rstb.2008.0284.
Carr, Steve A.; Liu, Jin; Tesoro, Arnold G. Transport and fate of microplastic particles in wastewater treatment plants. Water Research. 2016, 91: 174–182. PMID 26795302. doi:10.1016/j.watres.2016.01.002.
Habib, Daniel; Locke, David C.; Cannone, Leonard J. Synthetic Fibers as Indicators of Municipal Sewage Sludge, Sludge Products, and Sewage Treatment Plant Effluents. Water, Air, and Soil Pollution. 1998, 103 (1/4): 1–8. Bibcode:1998WASP..103....1H. S2CID 91607460. doi:10.1023/A:1004908110793.
Mintenig, S.M.; Int-Veen, I.; Löder, M.G.J.; Primpke, S.; Gerdts, G. Identification of microplastic in effluents of waste water treatment plants using focal plane array-based micro-Fourier-transform infrared imaging. Water Research. 2017, 108: 365–72. PMID 27838027. doi:10.1016/j.watres.2016.11.015.
Helcoski, Ryan; Yonkos, Lance T.; Sanchez, Alterra; Baldwin, Andrew H. Wetland soil microplastics are negatively related to vegetation cover and stem density. Environmental Pollution. 2020, 256: 113391. PMID 31662247. doi:10.1016/j.envpol.2019.113391.
Eerkes-Medrano, D.; Thompson, R.C.; Aldridge, D.C. Microplastics in freshwater systems: A review of the emerging threats, identification of knowledge gaps and prioritisation of research needs. Water Research. 2015, 75: 63–82. PMID 25746963. doi:10.1016/j.watres.2015.02.012.
Watts, Andrew J. R.; Lewis, Ceri; Goodhead, Rhys M.; Beckett, Stephen J.; Moger, Julian; Tyler, Charles R.; Galloway, Tamara S. Uptake and Retention of Microplastics by the Shore Crab Carcinus maenas. Environmental Science & Technology. 2014, 48 (15): 8823–30. Bibcode:2014EnST...48.8823W. PMID 24972075. doi:10.1021/es501090e.
Thompson, R. C.; Olsen, Y.; Mitchell, R. P.; Davis, A.; Rowland, S. J.; John, A. W.; McGonigle, D.; Russell, A. E. Lost at Sea: Where is All the Plastic?. Science. 2004, 304 (5672): 838. PMID 15131299. S2CID 3269482. doi:10.1126/science.1094559.
Wright, Stephanie L.; Thompson, Richard C.; Galloway, Tamara S. The physical impacts of microplastics on marine organisms: A review. Environmental Pollution. 2013, 178: 483–492. PMID 23545014. S2CID 17691860. doi:10.1016/j.envpol.2013.02.031.
Sun, Shuge; Shi, Wei; Tang, Yu; Han, Yu; Du, Xueying; Zhou, Weishang; Hu, Yuan; Zhou, Chaosheng; Liu, Guangxu. Immunotoxicity of petroleum hydrocarbons and microplastics alone or in combination to a bivalve species: Synergic impacts and potential toxication mechanisms. Science of the Total Environment. 2020, 728: 138852. Bibcode:2020ScTEn.728m8852S. PMID 32570313. doi:10.1016/j.scitotenv.2020.138852.
Tang, Yu; Zhou, Weishang; Sun, Shuge; Du, Xueying; Han, Yu; Shi, Wei; Liu, Guangxu. Immunotoxicity and neurotoxicity of bisphenol A and microplastics alone or in combination to a bivalve species, Tegillarca granosa. Environmental Pollution. 2020-10, 265 (Pt A): 115115. PMID 32806413. S2CID 221166666. doi:10.1016/j.envpol.2020.115115.
Risk, Michael J.; Edinger, Evan. Impacts of Sediment on Coral Reefs. Encyclopedia of Modern Coral Reefs. Encyclopedia of Earth Sciences Series. 2011: 575–586. ISBN 978-9048126385. doi:10.1007/978-90-481-2639-2_25.
Iannella, Mattia; Console, Giulia; D'Alessandro, Paola. Preliminary Analysis of the Diet of Triturus carnifex and Pollution in Mountain Karst Ponds in Central Apennines. Water. 2019, 44 (129): 11496–11506. doi:10.3390/w12010044.
Weis, Judith; Andrews, Clinton J; Dyksen, John; Ferrara, Raymond; Gannon, John; Laumbach, Robert J; Lederman, Peter; Lippencott, Robert; Rothman, Nancy. Human Health Impacts of Microplastics and Nanoplastics(PDF). NJDEP SAB Public Health Standing Committee. 2015: 23 [2018-09-25]. (原始內容存檔(PDF)於2018-04-17).
Catarino, Ana I.; MacChia, Valeria; Sanderson, William G.; Thompson, Richard C.; Henry, Theodore B. Low levels of microplastics (MP) in wild mussels indicate that MP ingestion by humans is minimal compared to exposure via household fibres fallout during a meal. Environmental Pollution. 2018, 237: 675–684. PMID 29604577. S2CID 4976211. doi:10.1016/j.envpol.2018.02.069. hdl:10026.1/11254.
Arvaniti O.S., Antonopoulou G., Gatidou G., Frontistis Z., Mantzavinos D., Stasinakis A.S. (2022) Sorption of two common antihypertensive drugs onto polystyrene microplastics in water matrices. Science of the Total Environment 837, 155786, https://doi.org/10.1016/j.scitotenv.2022.155786網際網路檔案館的存檔,存檔日期2022-09-24.
Y.Li, M.Li, Z.Li, L.Yang, X. Liu (2019) Effects of particle size and solution chemistry on triclosan sorption on polystyrene microplastic Chemosphere, 231, pp. 308-314, https://doi.org/10.1016/j.chemosphere.2019.05.116網際網路檔案館的存檔,存檔日期2022-09-24.
Fendall, Lisa S.; Sewell, Mary A. Contributing to marine pollution by washing your face: Microplastics in facial cleansers. Marine Pollution Bulletin. 2009, 58 (8): 1225–1228. PMID 19481226. doi:10.1016/j.marpolbul.2009.04.025.
Woodall, Lucy C.; Sanchez-Vidal, Anna; Canals, Miquel; Paterson, Gordon L.J.; Coppock, Rachel; Sleight, Victoria; Calafat, Antonio; Rogers, Alex D.; Narayanaswamy, Bhavani E.; Thompson, Richard C. The deep sea is a major sink for microplastic debris. Royal Society Open Science. 2014-12, 1 (4): 140317. PMID 26064573. doi:10.1098/rsos.140317.
Peng, X.; Chen, M.; Chen, S.; Dasgupta, S.; Xu, H.; Ta, K.; Du, M.; Li, J.; Guo, Z.; Bai, S. Microplastics contaminate the deepest part of the world’s ocean. Geochemical Perspectives Letters. 2018-11: 1–5. doi:10.7185/geochemlet.1829.
Onink, Victor; Wichmann, David; Delandmeter, Philippe; Sebille, Erik. The Role of Ekman Currents, Geostrophy, and Stokes Drift in the Accumulation of Floating Microplastic. Journal of Geophysical Research: Oceans. 2019-03, 124 (3): 1474–1490. PMID 31218155. doi:10.1029/2018JC014547.
Iwasaki, Shinsuke; Isobe, Atsuhiko; Kako, Shin'ichiro; Uchida, Keiichi; Tokai, Tadashi. Fate of microplastics and mesoplastics carried by surface currents and wind waves: A numerical model approach in the Sea of Japan. Marine Pollution Bulletin. 2017, 112 (1–2): 85–96. Bibcode:2017MarPB.121...85I. PMID 28559056. doi:10.1016/j.marpolbul.2017.05.057.
Luo, Yongming; Tu, Chen. Beat plastic pollution from the micro aspect: Towards sustainable development of researches in environmental microplastics. Chinese Science Bulletin. 2021-05-01, 66 (13): 1544–1546. doi:10.1360/TB-2021-0316.
Lebreton, Laurent C. M.; van der Zwet, Joost; Damsteeg, Jan-Willem; Slat, Boyan; Andrady, Anthony; Reisser, Julia. River plastic emissions to the world’s oceans. Nature Communications. 2017-08, 8 (1): 15611. PMID 28589961. doi:10.1038/ncomms15611.
Anderson, Julie C.; Park, Bradley J.; Palace, Vince P. Microplastics in aquatic environments: Implications for Canadian ecosystems. Environmental Pollution. 2016, 218: 269–280. PMID 27431693. doi:10.1016/j.envpol.2016.06.074.
Anderson, Philip J.; Warrack, Sarah; Langen, Victoria; Challis, Jonathan K.; Hanson, Mark L.; Rennie, Michael D. Microplastic contamination in Lake Winnipeg, Canada. Environmental Pollution. 2017-06, 225: 223–231. PMID 28376390. doi:10.1016/j.envpol.2017.02.072.
Evangeliou, N.; Grythe, H.; Klimont, Z.; Heyes, C.; Eckhardt, S.; Lopez-Aparicio, S.; Stohl, A. Atmospheric transport is a major pathway of microplastics to remote regions. Nature Communications. 2020-12, 11 (1): 3381. PMID 32665541. doi:10.1038/s41467-020-17201-9.
Auta, H.S.; Emenike, C.U; Fauziah, S.H. Distribution and importance of microplastics in the marine environment: A review of the sources, fate, effects, and potential solutions. Environment International. 2017, 102: 165–176. PMID 28284818. doi:10.1016/j.envint.2017.02.013.
Will Dunham. World's Oceans Clogged by Millions of Tons of Plastic Trash. Scientific American. 2019-02-12 [2019-07-31]. (原始內容存檔於2019-11-16). China was responsible for the most ocean plastic pollution per year with an estimated 2.4 million tons, about 30 percent of the global total, followed by Indonesia, the Philippines, Vietnam, Sri Lanka, Thailand, Egypt, Malaysia, Nigeria and Bangladesh.
Xanthos, Dirk; Walker, Tony R. International policies to reduce plastic marine pollution from single-use plastics (plastic bags and microbeads): A review. Marine Pollution Bulletin. 2017, 118 (1–2): 17–26. PMID 28238328. doi:10.1016/j.marpolbul.2017.02.048.