The Fluid Mechanics of Ocean Microplastics

<p indent="0mm">Microplastics (MPs) pollution has become a global environmental concern, and the ocean is a known sink for MPs. The marine environment provides the necessary living space and suitable environmental conditions for the growth and reproduction of seafood species. Meanwhile, MPs in the marine environment would be inevitably ingested by seafood species. Seafood species are of major importance to human beings, which are considered an important source of high-quality proteins and provide a wide range of healthful micronutrients. However, the growth, development and nutritional quality of seafood species are necessarily affected by MPs pollution, thus resulting in potential threats to seafood species and human health. Therefore, MPs pollution in seafood species has become an important and non-negligible issue in MPs pollution. This review summarizes the occurrence and distribution of MPs in global seafood species (e.g., crustaceans, bivalves, and fishes). The results indicate that MPs have been widely detected in seafood species all over the world, and the abundance range of MPs in the seafood species is 0–140 particles/individual, with the highest MPs concentration detected in American oysters (<italic>Crassostrea virginica</italic>, 140 items/individual). The ingestion behavior (e.g., swallowing-, filtering- and sucking-feeding) of the MPs for seafood species and the MPs contamination levels within the habitat of the seafood species are the main factors that affect the level of MPs pollution in their bodies. Besides, the particle size of MPs in seafood species ranges from <sc>0.006–5 mm,</sc> which is mainly restricted by the detection limit of the instrument. The results also show that fiber-shaped MPs are the most frequently detected shape in seafood species, as fibers are more likely to be trapped or entangled in the gill of seafood species compared to other shapes (such as fragment, particle and film). In order to effectively regulate the contamination of MPs in seafood species at source, the sources of MPs in seafood species are elucidated in depth, including terrigenous input, shipping emission, atmospheric deposition, and fishery activities. Notably, there is a special emphasis on the significant contribution of fishery activities to MPs pollution in the marine environment and seafood species. The results show that plastic fishing gears used in fishery activities, such as nets, ropes and buoys, release a large amount of MPs under photodegradation, wind and wave abrasion, and biological erosion, which are widely identified in seafood species. What is more, the results indicate that high levels of MPs are released due to intensive farming activities, which results in higher levels of MPs in farmed seafood species than in wild seafood species. Subsequently, due to a large amount of MPs accumulated in seafood species, the toxic effects of MPs on the growth and development, oxidative stress, immune response, and reproduction of seafood species are discussed, as well as the negative impact on the nutritional quality of seafood species. Humans, as the highest trophic level of the food chain, consume seafoods contaminated with MPs, which will be transferred to the human body through the trophic transfer. Therefore, the potential risks of MPs contamination (including its plastic additives and co-existing contaminants) of seafood species to human health are further summarized. Finally, this review also provides suggestions and prospects for future research directions on the prevention strategy and ecological risks of MPs in seafood species. This research contributes to better assessing the food safety of seafood species and their potential risks to human health.

The control of microplastic pollution in the marine environment has become a growing public concern in recent years. To better grasp the trends and development of microplastic pollution control in the marine environment, the published literature in Science Citation Index Expanded (SCIE) database of Web of Science Core Collection from 2013 to 2022, up to a total of 2,357 articles or reviews was analyzed through CiteSpace and VOSviewer tools. The results show an exponential growth in the number of papers related to the control of microplastic pollution in the marine environment, with China, United States, India, and Australia providing the main drivers, while China being the most active country, with Science of the Total Environment, Marine Pollution Bulletin, Environmental Pollution and Chemosphere being the most important sources for publishing relevant research. A relatively complete theoretical framework has been developed for the control of marine microplastic pollution, focusing on the quantification, traceability and collectability of microplastics. However, few papers have focused on policy implications and technological innovations in this area. The research on marine microplastic pollution control has transitioned from traceability and hazard analysis of microplastics to the impact of economic activities and synthetic fibre on microplastic pollution. Microplastics in wastewater discharged from municipal wastewater treatment plants, human consumption, man-made fibers and synthetic polymers have become the frontier of research. The present study is of significance for better understanding and supporting further research on the control of microplastic pollution in the marine environment.

Abstract. Wind work at the air-sea interface is the transfer of kinetic energy between the ocean and the atmosphere and, as such, is an important part of the ocean-atmosphere coupled system. Wind work is defined as the scalar product of ocean wind stress and surface current, with each of these two variables spanning, in this study, a broad range of spatial and temporal scales, from 10 km to more than 3000 km and hours to months. These characteristics emphasize wind work's multiscale nature. In the absence of appropriate global observations, our study makes use of a new global, coupled ocean-atmosphere simulation, with horizontal grid spacing of 2–5 km for the ocean and 7 km for the atmosphere, analyzed for 12 months. We develop a methodology, both in physical and spectral spaces, to diagnose three different components of wind work that force distinct classes of ocean motions, including high-frequency internal gravity waves, such as near-inertial oscillations, low-frequency currents such as those associated with eddies, and seasonally averaged currents, such as zonal tropical and equatorial jets. The total wind work, integrated globally, has a magnitude close to 5 TW, a value that matches recent estimates. Each of the first two components that force high-frequency and low-frequency currents, accounts for ∼ 28 % of the total wind work and the third one that forces seasonally averaged currents, ∼ 44 %. These three components, when integrated globally, weakly vary with seasons but their spatial distribution over the oceans has strong seasonal and latitudinal variations. In addition, the high-frequency component that forces internal gravity waves, is highly sensitive to the collocation in space and time (at scales of a few hours) of wind stresses and ocean currents. Furthermore, the low-frequency wind work component acts to dampen currents with a size smaller than 250 km and strengthen currents with larger sizes. This emphasizes the need to perform a full kinetic budget involving the wind work and nonlinear advection terms as small and larger-scale low-frequency currents interact through these nonlinear terms. The complex interplay of surface wind stresses and currents revealed by the numerical simulation motivates the need for winds and currents satellite missions to directly observe wind work.

The ocean-atmosphere system is intrinsically coupled, although feedbacks across the air-sea interface are often masked by temporal and spatial differences. Interactions between the ocean and atmosphere occur at the air-sea interface. The ocean surface forms a barrier to the exchange of heat, moisture, momentum and trace constituents (Rogers, 1995). The fundamental processes that connect the atmosphere and ocean are the energy input to the ocean by the wind, the net freshwater flux, expressed as precipitation and evaporation, and the net surface heat flux. The oceans play a substantial role in the changing radiative balance of the Earth and the climate. In particular, they affect gas and aerosol concentrations in the atmosphere as well as contemporary fluxes from the atmosphere to the ocean and from the ocean to the atmosphere. The energy from the atmosphere to the ocean surface enhances mixed layer during the circulation of the upper ocean. On the other hand, energy from the ocean affects atmospheric circulation, weather and climate. Among the influences of the oceans is their effect on gas and aerosol concentrations in the atmosphere. The global ocean is known to be a net sink of anthropogenic CO2 and hence the oceans have effectively slowed the build-up of this greenhouse gas in the atmosphere.

Environmental studies and oilspill trajectory modeling are conducted as part of the Outer Continental Shelf Oil and Gas Program administered by the U.S. Department of the Interior. The modeling work and related studies are coordinated efforts of the U.S. Geological Survey and the U.S. Bureau of Land Management. Oilspill trajectory modeling and physical oceanographic studies of areas off the southeastern coast of the United States have been in progress since 1976, and have been used in making decisions for two separate offshore lease sales. The initial oilspill trajectory model was modified to accommodate the findings of ongoing studies. Research carried out by investigators from government, universities, and the private sector has enlarged the data base and increased the understanding of oceanographic and meteorological processes observed in this region. Hypothesized ocean surface circulation patterns, originally based upon drift bottle returns, are now based upon a series of satellite observations, and will eventually be studied with three-dimensional time-dependent models. By correlating winds observed at data buoys with observed winds on land, correction factors have been developed to more accurately apply data from land-based meteorological stations for predicting winds on the ocean surface. As a consequence of this progress in understanding ocean circulation and surface winds, the oilspill trajectory analysis model for lease Sale 56 uses a data base substantially improved over that used for the earlier Sal e 43. Data from some trajectory models has been correlated with data on World War II tanker sinkings near Cape Hatteras, North Carolina. The knowledge gained through this continuing program illustrates the value of coordinated, long-term studies to improve decisionmaking in the marine environment. Introduction The U.S. Bureau of Land Management (BLM) offshore studies program sponsors environmental research and investigations of the effects associated with the sale of oil and gas leases on the U.S. Outer Continental Shelf (OCS). Initiated in 1974, the program first sponsored regional studies by scientific disciplines, and then pursued specific research pertinent to decisionmaking, addressing such issues as space use conflicts, pollutant transport, and fates and effects of pollutants. In all of the offshore regions, the problem of oilspills has generated a high level of concern. Consequently, numerous studies have been done to identify the locations and sensitivities of the biologic and economic resources that could be harmed by oilspills as well as studies of those processes, such as winds and ocean circulation, that could transport spilled oil to vulnerable resources. The U.S. Geological Survey (USGS) oilspill trajectory analysis (OSTA) model was developed in 1976 to bring together these various studies to aid in estimating possible environmental hazards associated with developing oil resources in OCS lease areas (1)(2). The OSTA model is a large, stochastic model which analyzes the probability of oilspill occurrence, as well as the likely movement of spills in relation to the locations of recreational and biological resources that may be vulnerable. The probability of oilspill occurrence is estimated from information on the anticipated level of oil production and the possible modes of transport.

Introduction: Microplastic (MP) pollution is now an important environmental issue, especially in marine environments, where it endangers marine mammals. The bioaccumulation of MPs in the food web causes different biological effects on apex predators like the marine mammals. MPs have the capacity to disrupt immune homeostasis through oxidative stress, inflammation, and immune dysfunction. The review is a synthesis of existing studies on how MPs affect the immune systems of marine mammals and the pathways of the immune system dysregulation, i.e., oxidative stress, chronic inflammation, and cytokine imbalance. Materials and Methods: This review combines experimental toxicology, mechanistic research, and environmental evaluation regarding exposure to microplastics in the marine environment. It concentrates on the rodent, fish, and aquatic invertebrate models because they are related to marine mammal immune systems. Such important techniques as the measurement of oxidative stress, inflammatory cytokines, and immune function should be mentioned. Also, the review brings out the effects of movements of toxic chemicals such as heavy metals and persistent organic pollutants (POPs) by MPs, which aggravate the immune dysfunction of exposed organisms. Results and Discussion: MP exposure leads to the dysregulation of the immune system by way of elevated reactive oxygen species (ROS), diminished antioxidant defense, and stimulation of the inflammatory cytokines. The level of ROS increased up to 50%, cytokines such as TNF-α, IL-6, and IL-1β B were increased by 30-60% in experimental models. There is impaired lipid metabolism and gut microbiota in marine mammal models, which further impair the immune system. The MPs are also the transporting agents of heavy metals and persistent organic pollutants, which enhance the immune disruptions. Marine mammals are most prone to chronic exposure data whereby MPs are found in major body parts such as liver, gastrointestinal tract and lungs. Conclusion: The health of marine mammals is increasingly endangered by the microplastic pollution that causes dysregulation of the immune system and predisposes them to disease. Due to the long-term exposure and bioaccumulation of the marine ecosystems, additional studies on the immunotoxicology of MPs on marine mammals are critical to the effective conservation and mitigation measures.

Microplastics in the coral ecosystems: A threat which needs more global attention

Microplastic pollution and its relationship with the bacterial community in coastal sediments near Guangdong Province, South China

Microplastic pollution (MP) in marine environments around the globe is severe and insufficient precautions have yet to be taken for its prevention. The focus of this study was on quantifying MPs from beach sediment and seawater samples and identifying their distributions and types along the western coast of Sri Lanka from the Kelani River estuary to the Mahaoya estuary. Nine sites along this 42 km stretch were selected, and random sampling was employed to collect a minimum of eight sediment samples from each site between October and December 2021. Water samples were also collected, parallel to the sediments, from the ocean surface. FTIR analysis revealed that most of the MPs found were polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), and phenol formaldehyde resin. The mean abundance of MPs varied from 2.0 ± 0.6 items/L to 161.0 ± 15.7 items/L in water samples and from 3.0 ± 0.3 items/m2 to 656.0 ± 34.5 items/m2 in sediment samples. The MPs found were identified in different shapes as fragments (80.2%), pellets (14.9%), fibers (2.7%), and foams (2.5%). Analysis revealed that the beach sediments were contaminated with PS, phenol formaldehyde resin, PET, PP, and PE, while the surface seawater was dominated by phenol formaldehyde resin, PS, PP, and PE.

The top few millimeters of the ocean surface, where properties are most altered relative to deeper water, are often referred to as the sea surface microlayer. Physics, chemistry, and biology of the sea surface microlayer are the subject of this chapter. Very close to the air–sea interface, turbulent mixing is suppressed and molecular diffusion appears to dominate the vertical property transport. The viscous, thermal, and diffusive sublayers close to the ocean surface that exist as characteristic features of the air–sea momentum, heat, and mass transport are considered. Their dynamics are quite complex due to the presence of surface waves, capillary effects, penetrating solar radiation, rainfall, and surface films due to the presence of surfactants. The existing theories of the sea surface microlayer, numerical model parameterizations, available observations and new approaches, including computational fluid dynamics modeling and DNA analysis of the bacterial content of the sea surface microlayer, are critically analyzed in this chapter.

Microplastic pollution has emerged as a severe transboundary threat to natural ecosystems, marine environments, and human and nonhuman health. Microplastic pollution and its consequent impacts on natural ecosystems and habitats have attracted the attention of experts, environmentalists, researchers, academia, decision-makers, and the governments across the globe. It is imperative to examine and analyze the existing trends and themes in microplastic pollution-related research. It is also important to identify the most productive countries, organizations, and journals focusing on microplastic pollution and its impacts. The analysis is also needed to pinpoint the keywords and thematic evolution in research on microplastic along with the most influential and effective research in the area. This study serves this purpose. The study uses a systematic bibliometric approach to trace out the most productive countries, organizations, sources, and documents on microplastic related research. The study also provides detailed analyses regarding collaborations among countries and organizations in research on microplastic pollution. It also provides a detailed analysis of keywords and thematic evolution regarding microplastic research. This chapter also finds some emerging trends in research regarding the COVID-19 pandemic and microplastic pollution. This chapter pinpoints prospects of research on microplastic pollution and its implications on natural ecosystems, marine environment, human and nonhuman health, and approaches for the effective control and management of microplastic pollution. The conclusion of this analysis also stresses the need for collective strategies and frameworks to manage the microplastic pollution in the COVID-19 outbreak and post-pandemic world.KeywordsMicroplastic pollutionBibliometric analysisMarine environmentWastewaterFresh waterHealth effectsCOVID-19 and microplastic pollutionBibliometric analysis

Abstract. Rangkuiti AM, Leidonald R, Maiyah N, Ishak MY. 2025. Microplastic pollution in the Belawan Estuary, Indonesia: Evidence from aquatic biota and polymer characterization. Biodiversitas 26: 2002-2010. Microplastic pollution causes widespread contamination of coastal and marine environments. Although microplastic pollution has been studied in marine and estuarine environments across Indonesia, studies in North Sumatra are lacking. This study assessed microplastics (Mps) contamination of aquatic organisms in the Belawan Estuary. Aquatic biota was captured using ambai fishing gear, and the intestines were dissected for analysis. After degrading the organic material using an alkaline digestion method, microplastic particles were identified based on their shape, size, and quantity. Four types were identified: fibers, films, fragments, and pellets. Pellet microplastics were the most abundant, with an average of 24.21 particles per gram in fish and an average of 13.62 particles per gram in crustaceans, followed by fibers, fragments, and films. The size of the microplastic particles ranged from 27 to 1940 ?m. The abundance of MPs was higher in fish (average: 63.899 particles per g) than in crustaceans (average: 30.97 particles per gram). Carnivorous fish species were most contaminated with microplastics, including Epinephelus areolatus, Plotosus lineatus, and Neotrygon kuhlii, all of which are demersal. Fourier-transform infrared spectroscopy identified six polymers: polypropylene, polystyrene, polyethylene, polyvinyl chloride, polyethylene terephthalate, and polyamide. This study highlights severe microplastic contamination in the Belawan Estuary and underscores the need for urgent action to address this environmental threat.

Abstract. Very-near-surface ocean currents are dominated by wind and wave forcing and have large impacts on the transport of buoyant materials in the ocean. Surface currents, however, are under-resolved in most operational ocean models due to the difficultly of measuring ocean currents close to, or directly at, the air–sea interface with many modern instrumentations. Here, observations of ocean currents at two depths within the first meter of the surface are made utilizing trajectory data from both drogued and undrogued Consortium for Advanced Research on Transport of Hydrocarbon in the Environment (CARTHE) drifters, which have draft depths of 60 and 5 cm, respectively. Trajectory data of dense, colocated drogued and undrogued drifters were collected during the Lagrangian Submesoscale Experiment (LASER) that took place from January to March of 2016 in the northern Gulf of Mexico. Examination of the drifter data reveals that the drifter velocities become strongly wind- and wave-driven during periods of high wind, with the pre-existing regional circulation having a smaller, but non-negligible, influence on the total drifter velocities. During these high wind events, we deconstruct the total drifter velocities of each drifter type into their wind- and wave-driven components after subtracting an estimate for the regional circulation, which pre-exists each wind event. In order to capture the regional circulation in the absence of strong wind and wave forcing, a Lagrangian variational method is used to create hourly velocity field estimates for both drifter types separately, during the hours preceding each high wind event. Synoptic wind and wave output data from the Unified Wave INterface-Coupled Model (UWIN-CM), a fully coupled atmosphere, wave and ocean circulation model, are used for analysis. The wind-driven component of the drifter velocities exhibits a rotation to the right with depth between the velocities measured by undrogued and drogued drifters. We find that the average wind-driven velocity of undrogued drifters (drogued drifters) is ∼3.4 %–6.0 % (∼2.3 %–4.1 %) of the wind speed and is deflected ∼5–55∘ (∼30–85∘) to the right of the wind, reaching higher deflection angles at higher wind speeds. Results provide new insight on the vertical shear present in wind-driven surface currents under high winds, which have vital implications for any surface transport problem.

Global awareness of microplastic contamination and its effects on the environment has grown. Plastics are resistant to breakdown and penetrate aquatic environments and are ultimately easily accessible to a wide range of aquatic animals and ultimately transported along the food web. Microplastics in cells and tissues have long-term consequences for marine organisms. A major factor in the spread of microplastics to the environment is their high adsorption capacity on the water surface. Microplastics and persistent organic pollutants interact to make the pollutants even more dangerous to living things. Microplastic pollution and its impact on the ecological environment have attracted worldwide attention. To effectively control microplastic pollution, there is a need to understand how Microplastics affect the ecological environment. This review discusses the formation, transfer and distribution of Micro plastics and the current physical, chemical and biological impacts on the environment. It is crucial to prevent plastic additives' overuse and enact laws and regulations to control plastic waste on account of the current threats posed by Microplastics to marine life and human health. We can eliminate marine litter by establishing plastic recycling schemes in the future or by promoting plastic awareness programs through both social and informational media.

Microplastic Pollution: Causes, Effects, and Control sheds light on the causes, effects, and control of microplastic pollution, providing valuable insights into the tools and techniques for analysis, the impact on ecosystems, and the potential risks to human well-being. The editors focus on the urgency of addressing this global environmental challenge through collaborative efforts and sustainable solutions. This reference features 10 edited chapters covering multiple aspects of microplastic pollution. The book introduces the reader to various tools and techniques used to analyze microplastic pollution in both aquatic and terrestrial ecosystems. It then examines the sources, pathways, and levels of microplastic contamination in the environment and explains how to evaluate the potential health risks for the nearby communities. The impact of microplastic on flora and fauna is presented in one chapter. To emphasize the importance of assessing microplastic contamination, the editors present a case study conducted in Thoothukudi, South India, to explore the implications of microplastic pollution on human health. The book also provides information on solutions to microplastic pollution including the use of bioplastics and removal techniques. Microplastic Pollution: Causes, Effects, and Control equips readers with a complete understanding of the global challenge of microplastics, fostering awareness and encouraging further research and action to protect our ecosystems and human health from their detrimental impact. It is an ideal handbook for environmental science researchers and students who need to understand microplastic pollution and plan environmental impact assessments for academic research and professional projects. Key Features - Comprehensive coverage of microplastic pollution with 10 structured chapters - Informs readers about important parameters to understand and measure the impact of microplastics on local fauna, flora and the surrounding environment - Covers evaluation and remediation of microplastics in both terrestrial and marine environments - Includes references for advanced readers - Includes a case study on the effect of microplastics in Thoothukudi, South India