UNIT 5 Monitoring methods for the sea floor

[Virtual Presenter] In this unit, we will investigate the techniques for monitoring plastic and microplastics on the sea floor. We will examine sample collection examples and the trends of microplastics deposition. Additionally, we will discuss the monitoring of microplastics on the sea floor. Let's get started with delving into this unit..

[Audio] We will discuss the methods and techniques used to monitor plastic and microplastics on the sea floor. Probabilistic sampling and targeted sampling are two sampling designs that can be used. Bulk sampling is the preferable technique when visual identification of plastic particles is not possible, while volume-reduced sampling is when a fraction of the sample containing microplastics is reduced for further analysis. Examples of investigations include the effect of sea depth and concentrated social activities on microplastics in seabed sediments, as well as the effect of ferry quays having intensive sea transportation on microplastics in seabed sediments. We can also determine spatio-temporal distribution of microplastics coming from industrial, agricultural and municipal sources. Through understanding these sampling techniques, we can understand the presence of plastic and microplastics in our ocean environment better..

[Audio] We are currently exploring the various techniques to monitor plastic and microplastics on the sea floor. We are concentrating on sample gathering and placement patterns. For the selection of the sampling sites, we can consider natural gyres and data on seafloor shape and depth that can be obtained from sources such as Chantaburi Buu Ac and NOAA websites. Surveying should be conducted along a transect perpendicular to the shoreline at sensible depth intervals..

[Audio] Selection of sampling sites is the most critical aspect of collecting data on plastic and microplastics on the sea floor. Man-made sources, such as urban areas, shipping routes, sources of pollution, and sea discharge points, must be considered. Likewise, sites along major shipping routes, such as marine, pier, stream, and deep-sea discharge sites, should be taken into account. To determine the best locations for sampling and monitoring plastic and microplastics, Google and other tools can be used..

[Audio] We will investigate the approaches employed to observe plastic and microplastics on the seabed. We will look at sample collection strategies and review different distribution trends. We will talk over the results of microplastics in the seabed and what this involves for the natural world. This is a convoluted issue and one that needs vast amounts of research and exploration. We will discuss the approaches and outcomes of what we discover so that we can more likely comprehend this issue and make educated choices that will help preserve our environment..

[Audio] We will be examining the methods of monitoring plastic and microplastics on the ocean floor, focusing on sample collection and sedimentation patterns. We will be studying sedimentary basins and deposition settings to grasp where microplastics are likely to accumulate. This comprehension will be essential when forming strategies to observe and diagnose microplastics on the sea floor..

[Audio] Sedimentary basins form an archive of information that can provide essential knowledge about the deposition of plastic and microplastics. The conditions of the seafloor, seabed substrate, and ocean currents all influence the shape and composition of sedimentary basins, and this in turn impacts the amount and type of plastic and microplastics that settle into them. Investigating sedimentary basins is vital for formulating successful strategies for monitoring plastic and microplastics on the ocean floor..

[Audio] Marine depositional environments have a direct impact on the quantity of plastic and microplastics that end up on the sea floor. This slide displays a table which outlines the principal transportation processes and depositional characteristics of the most typical marine ecosystems, along with the sediment types that typically accompany them. It's these attributes that define the quantity of plastic and microplastics present in each environment. Consequently, it is imperative to comprehend them in order to more accurately observe plastic and microplastics in the seabed..

[Audio] It is essential to understand the depositional environments and sedimentary basins in order to properly monitor plastic and microplastics in the ocean floor. The environment can be divided into five distinct types: shallow marine, lagoonal, submarine fan, and deep water. Each of these has its own transport processes, sediments, and settings. Being familiar with the characteristics of these environments and the type of sediment they contain is essential when creating effective monitoring strategies..

[Audio] Microplastics are an increasingly worrying environmental problem, especially in relation to our oceans. This slide explores where microplastics are deposited. As shown, microplastics concentrate in two primary habitats: shallow coastal regions and the deep sea. In coastal regions, microplastics are mostly located near sources of plastic pollution, such as rivers or harbors. In the deep sea, they typically settle on the sea floor. Both of these habitats contain a range of organisms and play important roles in the marine ecosystem. Establishing the effects of microplastics on these habitats is essential for maintaining the well-being of our oceans..

[Audio] Plastic is becoming an ever-growing issue in our oceans, with microplastics becoming a major pollutant of the marine environment. In this unit, we will look into the ways of monitoring the spread of plastic and microplastics on the sea floor. We will investigate the methods used to collect samples from shallow coastal areas, and learn how to identify and monitor the trends in deposition of plastic and microplastics..

[Audio] Examining the methods for monitoring plastic and microplastics on the sea floor, we observe that shallow coastal microplastics are mostly deposited by river. Furthermore, large quantities of macro plastics greater than 5 millimeters are also deposited. Additionally, both plastic and microplastic particles tend to move to deeper parts of the sea as a result of turbidity currents..

[Audio] In regards to monitoring plastic and microplastics on the sea floor, there are two main methods. Gravity flow deposits form when heavier particles settle out of suspension and form a layer on the sea floor. Ocean current-related deposits are formed when there is a higher concentration of particles due to the motion of ocean currents. These deposits can be monitored to assess the level of plastic in the ocean..

[Audio] We will be exploring the various techniques of monitoring plastic and microplastics on the seafloor in this unit. One such method is gravity flow deposits, also known as turbidites, wherein plastic fragments are sorted based on their density, size and shape. Basing on the Bouma (1962) type of turbidites, the plastic fragments are observed to be concentrated in the upper divisions, particularly the C-E divisions. Moreover, the behavior of plastic fragments is found to be similar to non-spherical particles, such as robust shell fragments, which mostly end up in the bottom beds. In contrast, less dense shells are generally located at the higher levels, in the ripple-laminated Bouma C division..

[Audio] Turbidity currents are responsible for the deposition of particles on the sea floor. The settling velocity of the particles affects the speed at which they reach the bottom and the eventual pattern of deposition. For example, dense, spherical particles that have high settling velocities tend to be concentrated at the base of the flow, while platy particles or fibers with low settling velocities may be dispersed throughout the flow due to turbulent mixing. This has important implications when monitoring plastic and microplastics on the sea floor..

[Audio] Today we will discuss the various methods used for monitoring plastic and microplastics on the seafloor, including sample collection and deposition trends. It is critical to consider the amount of sediment fall out when determining trends in deposition. Zones where the flow has been forced to decelerate rapidly due to either being overloaded with sediment or due to topography will typically display high sediment fall out rates. On the other hand, flows that decelerate less rapidly, such as concentrated flows running out over gradually decreasing slopes, will exhibit lower sediment fall out rates because the turbulent kinetic energy dissipates more slowly..

[Audio] There is a distinction between high and low density turbidites in terms of the amount of sediment that is classified and the kind of deposit that is produced from it. Technology now offers more choices in the kind of media that we consume..

Gravity Flow Deposits. 1 • clay S fiber mp fragment C) quartz Low low Us/U* S moderate Us/U* highUs/U* O Characteristic profile High Grain distribution in flow Normalised / velocity profiles.

[Audio] We will be discussing ocean current-related deposits and their effect on plastic and microplastics on the sea floor. We will look at how water currents move, transport and deposit particles of microplastics. We will also discuss how ocean currents affect the way in which plastic accumulates and is subsequently deposited onto the sea floor. Finally, we will assess the effects of these deposits and determine the necessary steps in order to effectively monitor them. Let's get started..

[Audio] This slide focuses on the methods for monitoring plastic and microplastics on the sea floor, with a special focus on sample collection and deposition trends. It is noteworthy that microplastics being brought to the basin floor may be subject to erosion, bottom current transfer, and eventual sequestration within drift deposits. Drift deposits are often composed of fine-grained, clay-silt and may demonstrate strength variability throughout time. Conversely, bottom current deposits tend to be more uniform and less distinguishable compared to gravity current deposits because bottom currents are usually consistent, although they may show seasonal changes..

[Audio] The slide focused on analysing the methods for monitoring plastic and microplastics on the sea floor. This involves collecting samples and studying potential deposition trends. Additionally, currents which have a speed of 0.06 to 0.5 m/s can transport microplastics, for instance fibres, and can even cause them to enter deeper sediment as a result of high bioturbation. Benthic organisms may also ingest these microplastics. This therefore implies the necessity of a precise monitoring of microplastics in order to understand their effect on the environment..

[Audio] Analysing the amount of plastic and microplastics on the sea floor requires taking samples and studying sedimentary structures and particle size. There are two processes causing the formation of plastic and microplastics on the sea floor: suspension settling and hemipelagic settling. Suspension settling is when fine fragments and fibres are present in the water column, causing larger particles to be deposited by reversing their buoyancy. Hemipelagic settling occurs due to structures and laminations that are not derived from the water column. By using these methods, we can obtain useful information about the amount of plastic and microplastics on the sea floor..

[Audio] This unit examines techniques for examining plastic and microplastics in the ocean bed. We explore sample collection and deposition structures, and investigate the grain size, sedimentary structures, indications of low-density turbidity, microplastics at the bed top, and their susceptibleness to erosion in turbulent environs. This all provides insight into how sediment is moving along the sea floor and how plastic and microplastics are affecting ocean ecosystems..

[Audio] The slide shows a description of a bed type characterized by a medium to very coarse and granular grain size, and is dominantly structureless. This type of bed is assumed to have been created by deposition from a high density turbidity current. Microplastics are also present and scattered throughout the bed, with higher concentrations at the bed tops, making them especially prone to erosion. A high density turbidity current is a type of sediment-laden water flow that is denser than the ambient fluid, causing it to flow rapidly downslope..

[Audio] We examine the techniques for tracing plastic and microplastics on the sea floor. We analyze sample collection and laying down movements and how they can inform our comprehension of the presence of plastics and microplastics on the sea floor. The grain size ranges from fine to medium sand and sedimentary structures such as bowing and dewatering structures are evident here, which are proof of deposits from turbidity currents and debris flows. As for microplastics, they are concentrated on the bottom of the beds and in mud heavy divisions which usually form during the transformation from debris flows. Finally, we observe hybrid flow, a mixture of turbidity current flow and debris flow..

[Audio] "In this slide, we discuss the methods for monitoring plastic and microplastics on the sea floor. Specifically, we are looking at the grain size, sedimentary structures like diamic and plastic deformations, and interpretation of the deposition processes of debris flows. Microplastics, in particular, tend to be distributed throughout the bed, and deposited in topographic lows. Ultimately, these findings demonstrate the prevalence of microplastics, and the need for better monitoring and preventive measures..

[Audio] As we can observe in this slide, a slump is a type of sedimentary structure that is formed when a large mass of material rapidly moves downslope due to gravity. Slumps are usually seen in areas of higher topographic relief, such as slopes and canyons, and typically contain the materials with which they are formed. However, this slide also talks about microplastics which can be remobilised from the host sediment, allowing them to mix with seawater and spread. This slide is important as it highlights the need to monitor plastic and microplastic pollution on the sea floor..

[Audio] To understand the impact of plastic pollution on the sea floor we need to look at the methods of monitoring plastic and microplastics on the sea floor. Structure and interpretation of the bed type is essential when assessing how plastic and microplastics are released from the sediment. This includes coherent bedding with thrust planes, sheared bedding contacts, and features from extensional and compressional forces. The sediment is vulnerable to gravitational instability which can cause it to move downslope initially as a coherent mass, potentially preserving internal structures. Microplastics may remain within the slides or be remobilised and released from the host sediment. This has the potential to mix the microplastics with the seawater, dispersing them further..

[Audio] We will be discussing methods for monitoring plastic and microplastics on the sea floor. Sample collection and deposition trends will be examined, specifically those related to sedimentary structures characterised by a winnowed tractional deposit. These deposits form at the base of a channel, scour or bedform trough and typically result from the passage of multiple flows. It's thought that larger microplastics may be trapped within these basal lag deposits and may be liable to erosion and downslope reworking, leading to a tractional lag. The aim is to gain insight into the deposition trends of plastic and microplastics on the sea floor..

[Audio] I will discuss methods for monitoring plastic and microplastic on the sea floor, including sample collection and deposition trends. Bed type description can provide an insight into the origin and physical features of these seafloor deposits; grain size ranges from silt to fine sand, and sedimentary structures such as plane-parallel and ripple-cross lamination, mud draped foresets and laminae, variable grading, and internal erosion surface, as well as bioturbation, are often observed. Deep water sediment gravity flow silts and sands are reworked by tractional currents attributed to bottom currents, known as thermohaline flows. Microplastics may act to concentrate fine microplastics and in particular microfibers, but this mechanism is still poorly understood. Bottom current reworking is an important factor to consider when monitoring plastic and microplastics on the sea floor..

[Audio] This unit focuses on the methods for monitoring plastic and microplastics on the seafloor. Sample collection is important, but we are also studying sedimentation trends. The seafloor sediment is generally clay and silt, with plane parallel and low angle dipping lamination. The sediment may or may not be bioturbated as well. It is thought to be created by sediment gravity flow and hemipelagites, which are then reworked by bottom currents. These currents may lead to the concentration or removal of fine microplastics, particularly fibers, in certain locations, which can then be spread across the seafloor..

[Audio] We will focus on how plastic and microplastics are monitored on the sea floor in this slide. Sample collections and deposition trends will be looked at. The implications for the long-term distribution of microplastics within different sedimentary settings – such as open continental slopes, submarine canyons, channels and lobes, abyssal plains and deep sea trenches – as well as what this means for benthic ecosystems will also be considered..

[Audio] Open continental slopes are critical but largely overlooked sections of the seafloor. Located between the continental shelf and the base of the slope/basin floor, they are hotspots of sediment accumulation. In addition, longshore currents that flow along the continental shelf may make them a hotspot for microplastic accumulation. A better understanding of how plastic and microplastics are monitored and collected from open continental slopes is essential..

[Audio] We are aware that submarine landslides can transport sediment in large amounts to the seafloor. This serves as a mechanism for large quantities of microplastics which may have built up over time to be re-deposited further down the sea floor. Gathering samples from the bottom of the ocean can enable us to comprehend better the spreading of plastic and microplastics in our seas..

[Audio] Monitoring plastic and microplastics on the sea floor is a complex task with many different methods to consider. In this unit, we will investigate sample collection and deposition trends, particularly on open slopes. Open slopes are often areas where fine microplastics, mainly fibers, gather due to advection from the coast together with shelf width, location of canyons, and prevalence of longshore currents. Furthermore, ocean currents can cause along-slope redistributions in drifts that show the pattern and strength of near-bed bottom currents. Lastly, rare but powerful submarine landslides may happen which can uncover large areas of previously stored microplastics and disperse them further down-slope. We will now look at these methods in greater detail..

[Audio] In this unit, we will explore the methods for monitoring plastic and microplastics on the sea floor. We will investigate sample collection and deposition trends in submarine canyon-channel-lobe-systems. Submarine canyons are common features along continental margins, usually formed seaward of major rivers. As we move toward the continental rise, canyons flare out and become less steep. Studies of modern canyon systems and linked deep-water fans have revealed that sustained turbidity currents are very efficient in transporting organic material and microplastics into the deep-water. By understanding these currents, we can better predict the pathways of microplastics and ultimately discover the most effective ways to monitor them..

[Audio] Canyons can be powerful forces of nature, capable of generating large-scale flows which can eradicate sediment that has accumulated in them. Recent studies suggest that terrace deposits and levees in the oceans are storing deep-sea microplastics. Therefore, canyon flushing could potentially cause microplastics to be displaced. Moreover, canyon flushing could have an influence in the long-term sequestration of microplastics in the overbank regions..

[Audio] We are looking at approaches to keep track of plastic and microplastics on the seafloor. Submarines' channels are used for transporting sediment. They usually don't have turbidity currents, and coarser elements are likely to settle in the bottom part. Plastic and microplastics can be moved to levees, terraces, and wider channel zones. Knowing the locations where plastic and microplastics are deposited is essential for understanding their effect on ocean life and the environment..

[Audio] Submarine channels can be preserved by internal and external levees, though these can be susceptible to erosion. In thick turbidites, repeated turbidity currents will generally only leave the lowermost and coarsest fraction of individual beds in the channel axis, which has implications for sediment deposition and understanding the effects of plastic and microplastics on the sea floor..

[Audio] Submarine channels on the ocean floor have been found to cause intra-channel erosion, resulting in poor preservation of deposits. This has implications for plastic and microplastic accumulation in the ocean floor, as these materials are often carried in and temporarily stored in channel axes. However, it appears that terraces and levees are the most probable locations for long-term accumulation of such substances..

[Audio] Submarine Lobes are sediment routing systems with siliciclastic sediment such as mud and organic material often present on their upper surfaces. This sediment is transferred through the system from the feeder channel with characteristics of thinning and increase of fineness away from the channel. In this unit, we will look at methods of monitoring plastic and microplastics in the sea floor, including sample collection and deposition trends associated with the sediment routing systems..

[Audio] We are examining the methods for monitoring plastic and microplastics on the sea floor, focusing on the sedimentary facies that occur at different points of a lobe. Moving away from the axis of the lobe and towards the fringes, turbidites become thinner and less dense. This recurring turbidity current activity is responsible for transferring lighter material to the outermost parts of the lobe..

[Audio] The focus of this unit is on the sea floor and monitoring plastic and microplastics there. Turbidity currents can cause sediment to form a dense, cohesive flow on the sea floor. Hybrid beds often form with an ungraded muddy-sand division, containing a lot of organic material, thus making it a likely place for microplastics to become incorporated and less likely to be eroded. In conclusion, it has been observed that the distal fringes of lobes in major submarine sediment routing systems can be hotspots for microplastic accumulation..

[Audio] Located deep within the ocean, the abyssal plain is one of the most distant regions on the planet. Reaching depths of up to 10 kilometers, it is a largely unfamiliar area with very few forms of life due to the extreme temperatures and darkness. This unit focuses on the research and methods used to monitor the plastic and microplastics present on the sea bed, including collection and deposition. Most of the sediment on the abyssal plain is a result of pelagic settling, though this may be influenced by bottom currents. Plastic and microplastics have the potential to be transported by these currents, caused primarily by biofouling, ultraviolet light degradation, and fragments from ships and fishermen. Therefore, monitoring the levels of plastic and microplastics in the abyssal plain sediments is absolutely necessary to gain a fuller understanding of the deep-sea sedimentation and its consequences on the environment..

[Audio] We have studied the techniques for detecting plastic and microplastics on the seabed. Studies demonstrate that deep-sea canyons contain exceptionally high quantity of microplastics which may be transported by bottom currents and water column settling. Moving on, we will focus on the Sun, the key energy source for living creatures on Earth..

[Audio] Microplastics in the ocean has become a concerning environmental issue. Not only does it have the potential of polluting the ocean, but what's more concerning is how these particles can be ingested by marine organisms and affect their health. Research on the sea floor has focused largely on canyons, which may previously have been overlooked as a repository for microplastics, yet their presence can drastically decrease the health of the benthic ecosystem. Polychaetes, bivalves, and copepods have been known to consume microplastics which, when absorbed and concentrated, can be further consumed by other organisms, resulting in additional harm. This evidence emphasises the need for further monitoring of plastic and microplastics on the sea floor in order to effectively address their long-term implications..

[Audio] We are providing some important information on our live Q&A session which will focus on methods for monitoring plastic and microplastics on the sea floor. These methods include sampling and observing the behaviour of polymers deposited on the ocean floor, as well as tracking their distribution. We are eager to engage in an informative dialogue about this significant ecological issue..

[Audio] The ocean floor contains a large amount of plastic and microplastics, impacting the health of the oceanic environment. It is therefore vital to monitor the amount of these materials in order to assess the consequences of plastic pollution. In this unit, we will look at two methods of assessing the quantity of plastic and microplastics on the sea floor: sample collection and deposition trends. After exploring these two approaches, the importance of monitoring plastic and microplastics on the sea floor will be understood..

[Audio] It is important to summarise the topics of discussion that we have been exploring over the past couple of weeks. We discussed methods of monitoring plastic and microplastics on the sea floor, including sample collection and deposition trends. Additionally, we looked at pertinent literature such as Alomar, Estarellas and Deudero's 2016 article Microplastics in the Mediterranean Sea: Deposition in coastal shallow sediments, spatial variation and preferential grain size, as well as Chen, Du, Jin, Chen, Dasgupta, Li, Xu, Ta and Peng's 2020 article Forty-year pollution history of microplastics in the largest marginal sea of the western Pacific. We have learned a great deal from this material and its applications are many. I wish you all the best in your studies..