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Systematic identification of microplastics in abyssal and hadal sediments of the Kuril Kamchatka trench
Abstract
The occurrence of microplastics throughout marine environments worldwide, from pelagic to benthic habitats, has become serious cause for concern. Hadal zones were recently described as the “trash bins of the oceans” and ultimate sink for marine plastic debris. The Kuril region covers a substantial area of the North Pacific Ocean and is characterised by high biological productivity, intense marine traffic through the Kuril straits, and anthropogenic activity. Moreover, strong tidal currents and eddy activity, as well as the influence of Pacific currents, have the potential for long distance transport and retention of microplastics in this area. To verify the hypothesis that the underlying Kuril Kamchatka Trench might accumulate microplastics from the surrounding environments and act as the final sink for high quantities of microplastics, we analysed eight sediment samples collected in the Kuril Kamchatka Trench at a depth range of 5143–8250 m during the Kuril Kamchatka Biodiversity Studies II (KuramBio II) expedition in summer 2016. Microplastics were characterised via Micro Fourier Transform Infrared spectroscopy. All samples were analysed in their entirety to avoid inaccuracies due to extrapolations of microplastic concentrations and polymer diversities, which would otherwise be based on commonly applied representative aliquots. The number of microplastic particles detected ranged from 14 to 209 kg⁻¹ sediment (dry weight) with a total of 15 different plastic polymers detected. Polypropylene accounted for the largest proportion (33.2%), followed by acrylates/polyurethane/varnish (19%) and oxidized polypropylene (17.4%). By comparing extrapolated sample aliquots with in toto results, it was shown that aliquot-based extrapolations lead to severe under- or overestimations of microplastic concentrations, and an underestimation of polymer diversity.
... Identifying the sources and pathways of plastic discharge is essential to better manage plastic production and its marine discharge. MPs are ubiquitous in marine environments: sea surface (de Lucia et al., 2014;Isobe et al., 2017;Pan et al., 2019), intertidal sediments (Sagawa et al., 2018;Vianello et al., 2013;Bergmann et al., 2017;Woodall et al., 2014), and deep-sea sediments (Peng et al., 2018;Peng et al., 2020;Zhang et al., 2020;Abel et al., 2021Abel et al., , 2022Qi et al., 2022). However, most research has been conducted in coastal areas, and the distribution of MPs in the deep sea remains unclear (Martin et al., 2022) due to limited sampling opportunities. ...
... 8-10; 5707-5813 m depth), MP abundance at our stations was 4137-18,720 times greater than that in the New Britain Trench (5800 m depth) (Peng et al., 2020). An overwhelmingly greater amount of MPs was also present in our hadal stations (St. 4 and 5) than that previously reported; MP abundance in our hadal trench stations ranged from about 1.3 to 1000 times greater than that in the trenches (Peng et al., 2018;Peng et al., 2020;Abel et al., 2021Abel et al., , 2022, and ranged from 148 to 272 times more than that in the New Britain Trench (Table S5). ...
... In the Japan Trench, MPs found in the turbidite layers were associated with earthquakes (Kawamura et al., 2020). Studies on sediment MPs in trench areas are scarce; however, MPs in sediments in the hadal area of the Mariana Trench and other trench areas were considerably lower (Peng et al., 2018;Peng et al., 2020;Abel et al., 2021Abel et al., , 2022 than those in the present study (Table S5). Our hadal stations were close to land with high human activity, and frequent submarine landslides and turbidity currents supply sediments to the triple junction at the hadal stations, which may have resulted in a higher supply of MPs than previously observed in trench areas. ...
... In fact, the first reason may explain the predominance of packaging material and single-use plastic items in the trench as this is one of the largest uses of plastic on global scale (Geyer et al., 2017). The location explains the high quantities of lines, cords and ropes as the Kuril Islands adjacent to the trench, are intensely exploited as naval trade routes, and fishery (Abel et al., 2021). Compared to other sources of plastics, those that predominate, whether on a global or local scale, are likely to contribute a greater proportion to the total plastic load (Boucher and Billard, 2019). ...
... Nevertheless as, especially in the marine realm, the breakdown of larger plastic debris into MP is largely discussed (Jahnke et al., 2017), the attention should be draw on the contribution of larger plastic litter to the ocean MP budgets. A common evidence in literature is that the abundances of plastic particles increase with decreasing particle size (Abel et al., 2021) supporting the idea that debris floating in the ocean, exposed to weathering effects, break down into smaller and smaller fragments and becomes increasingly preponderant in the ocean MP budget (ter Halle et al., 2016). The deep-sea is considered an especially important depocenter for those plastic debris and MP that are not retained by the rivers or are not stranded after entering the ocean (Weiss et al., 2021). ...
... The similarity of the polymer composition between marine debris and MP is, anyway, not to be taken for granted and depends on the type of polymer considered. Studies (Abel et al., 2021;2022) reported the presence of MP in the deep sediment of the KKT, and this was spectroscopically characterized in its chemical composition revealing 14 to 15 different polymer types. Accordingly, to these findings, MP was mostly identified as Acrylates/(Polyurethane) PUR/varnish PE and PP and a minor proportion by, ethylene vinyl acetate (EVA), polyamide (PA), polycarbonate (PC), polyvinyl chloride (PVC) and polyester/polyethylene terephthalate (PEST). ...
The global increase of plastic production, linked with an overall plastic misuse and waste mismanagement, leads to an inevitable increase of plastic debris that ends up in our oceans. One of the major sinks of this pollution is the deep-sea floor, which is hypothesized to accumulate in its deepest points, the hadal trenches. Little is known about the magnitude of pollution in these trenches, given the remoteness of these environments, numerous factors influencing the input and sinking behavior of plastic debris from shallower environments. This study represents to the best of our knowledge the largest survey of (macro)plastic debris sampled at hadal depths, down to 9600 m. Industrial packaging and material assignable to fishing activities were the most common debris items in the Kuril Kamchatka trench, most likely deriving from long-distance transport by the Kuroshio extension current (KE) or from regional marine traffic and fishing activities. The chemical analysis by (Attenuated Total Reflection Fourier transform infrared (ATR-FTIR) spectroscopy revealed that the main polymers detected were polyethylene (PE), polypropylene (PP) and nylon. Plastic waste is reaching the depths of the trench, although some of the items were only partially broken down. This finding suggests that complete breakdown into secondary microplastics (MP) may not always occur at the sea surface or though the water column. Due to increased brittleness, plastic debris may break apart upon reaching the hadal trench floor where plastic degrading factors were thought to be, coming off. The KKT's remote location and high sedimentation rates make it a potential site for high levels of plastic pollution, potentially making it one of the world's most heavily contaminated marine areas and an oceanic plastic deposition zone.
... Microplastic (MP) pollution, is demonstrated to affect the majority of the marine realm, at all latitudes, longitudes and depths (Bucol et al., 2020;Kelly et al., 2020;La Daana et al., 2020;Peeken et al., 2018;Reed et al., 2018;Roscher et al., 2021a). The ubiquity and the long-lasting durability of plastics, together with the global increase of its production Science of the Total Environment 838 (2022) 156035 hadal sediments of the trench (Abel et al., 2021) confirming the presence of MP in the deepest part of the trench. Several deep-sea related studies further identified MP in other Pacific trenches (Jamieson et al., 2019b;Zhang et al., 2020), hypothesizing that this environment could indeed act as an ultimate sink for MP pollution. ...
... Fenton treatment and second density separation. Fenton reaction was carried out following the protocol suggested in studies by Tagg et al. (2017), Bergmann et al. (2017a), Hurley et al. (2018), Tekman et al. (2020) and Abel et al. (2021), and are descried in detail in SI. After the Fenton reaction, the treated samples were removed from the filters by placing them in 150 mL glass beakers containing 50 mL of NaBr solution and sonicated for 5 min at 160 W / 35KHz. ...
... Analytical filter preparation for <500 μm fraction. To establish the particle concentration in the treated sample suspensions, a FlowCam (Fluid Imaging Technologies, Portable version IV, Scarborough, Maine, US) was used to quantify the particle concentration in a subsample (100 μL) (Abel et al., 2021;Lorenz et al., 2016;Bergmann et al., 2019). This concentration values were then applied to calculate the sample volumes that would be suitable for individual FTIR measurement. ...
... Microplastic (MP) pollution, is demonstrated to affect the majority of the marine realm, at all latitudes, longitudes and depths (Bucol et al., 2020;Kelly et al., 2020;La Daana et al., 2020;Peeken et al., 2018;Reed et al., 2018;Roscher et al., 2021a). The ubiquity and the long-lasting durability of plastics, together with the global increase of its production Science of the Total Environment 838 (2022) 156035 hadal sediments of the trench (Abel et al., 2021) confirming the presence of MP in the deepest part of the trench. Several deep-sea related studies further identified MP in other Pacific trenches (Jamieson et al., 2019b;Zhang et al., 2020), hypothesizing that this environment could indeed act as an ultimate sink for MP pollution. ...
... Fenton treatment and second density separation. Fenton reaction was carried out following the protocol suggested in studies by Tagg et al. (2017), Bergmann et al. (2017a), Hurley et al. (2018), Tekman et al. (2020) and Abel et al. (2021), and are descried in detail in SI. After the Fenton reaction, the treated samples were removed from the filters by placing them in 150 mL glass beakers containing 50 mL of NaBr solution and sonicated for 5 min at 160 W / 35KHz. ...
... Analytical filter preparation for <500 μm fraction. To establish the particle concentration in the treated sample suspensions, a FlowCam (Fluid Imaging Technologies, Portable version IV, Scarborough, Maine, US) was used to quantify the particle concentration in a subsample (100 μL) (Abel et al., 2021;Lorenz et al., 2016;Bergmann et al., 2019). This concentration values were then applied to calculate the sample volumes that would be suitable for individual FTIR measurement. ...
Microplastic (MP) pollution affects almost all ecosystems on Earth. Given the increasing plastic production worldwide and the durability of these polymers, concerns arise about the fate of this material in the environment. A candidate to consider as a depositional final sink of MP is the sea floor and its deepest representatives, hadal trenches, as ultimate sinks. In this study, 13 sediment samples were collected with a multiple-corer at depths between 5740 and 9450 m from the Kuril Kamchatka trench (KKT), in the Northwest (NW) Pacific Ocean. These samples were analysed for MP presence in the upper sediment layer, by slicing the first 5 cm of sediment cores into 1 cm horizontal layers. These were compared against each other and between the sampling areas, in order to achieve a detailed picture of the depositional system of the trench and small-scale perturbations such as bioturbation. The analyses revealed the presence of 215 to 1596 MP particles per kg ⁻¹ sediment (dry weight), with a polymer composition represented by 14 polymer types and the prevalence of particles smaller than 25 μm. A heterogeneous microplastic distribution through the sediment column and different microplastic concentration and polymer types among sampling stations located in different areas of the trench reflects the dynamics of this environment and the numerous forces that drive the deposition processes and the in situ recast of this pollutant at the trench floor.
... To solve this di culty and optimize lter analysis, the volume of the samples was often divided among several anodisc lters. The extra effort needed to analyse additional samples was essential to avoid any loss of information due to the subsampling procedure [34].In the scope of this study only one lter could be analyzed due to the large effort involved in the manual data analysis. This may impact the overall results as polymer types present might not be fully represented or their number affected by an over-or underestimation [34]. ...
... The extra effort needed to analyse additional samples was essential to avoid any loss of information due to the subsampling procedure [34].In the scope of this study only one lter could be analyzed due to the large effort involved in the manual data analysis. This may impact the overall results as polymer types present might not be fully represented or their number affected by an over-or underestimation [34]. Thus the sample from Chur might be more strongly in uenced than all other samples and this is also indicated by the calculated error value of 833 particles/m³. ...
The issues surrounding micro- and nanoplastics (MPs and NPs) are gaining importance as the knowledge about their distribution and impacts on the environment and human health grows. In order to gain a better understanding about the occurrence of those plastic particles and the pollution of different freshwater systems, the project, “Rheines Wasser” were conducted. This project investigated the entire 1,232.7 km-length of Europe’s Rhine River, which serves an important function for both transportation and water supply for several million people. Surface water samples of the river were filtered and the microplastic (MP) particles were detected by Fourier transform infrared microscopy. At several sample stations, different concentrations of MP-particles were found, ranging from 5 to 5326 particles/m ³ .
... Zinc chloride, sodium chloride, and sodium iodide were often used as flotation solutions to extract MPs from sediment samples (Fang et al., 2021;Patti et al., 2020;Sunitha et al., 2021). In addition, studies assessing sediments with high organic matter amounts also included oxidative treatment generally using hydrogen peroxide (Abel et al., 2021). Thirty-five different mesh sizes were used ranging from 0.45 to 1000 μm, which may affect recoveries for each method, thus influencing the size distribution of the reported MP frequency ). ...
... MPs with different characteristics could manifest different environmental fates and biological impacts. For example, denser MPs preferentially accumulate in sediment layers (Abel et al., 2021), while sizes, shapes, and surface charges of MPs also affect the exposure pathways and toxic effects of MPs on organisms (Borges-Ramírez et al., 2020;Ding et al., 2022;Matthews et al., 2021). In addition, the concentrations of MPs reported in different studies using non-harmonized methods for sampling, digestion, flotation, and separation may largely influence spatial comparison and conclusion . ...
Microplastics (MPs) become ubiquitous contaminants in Marine Protected Areas (MPA) that have been planned as a conservation strategy. The present study provides a comprehensive overview of the occurrence, abundance, and distribution of MPs potentially affecting MPA worldwide. Data on MP occurrence and levels in sediment and biota samples were collected from recent peer-reviewed literature and screened using a GIS-based approach overlapping MP records with MPA boundaries. MPs were found in 186 MPAs, with levels ranging from 0 to 9187.5 items/kg in sediment and up to 17,461.9 items/kg in organisms. Peaked MPs concentrations occurred within multiple-use areas, and no-take MPAs were also affected. About half of MP levels found within MPA fell into the higher concentration quartiles, suggesting potential impacts on these areas. In general, benthic species were likely more affected than pelagic ones due to the higher concentrations of MP reported in the tissues of benthic species. Alarmingly, MPs were found in tissues of two threatened species on the IUCN Red List. The findings denote urgent concerns about the effectiveness of the global system of protected areas and their proposed conservation goals.
... In addition to these investigations of toxicity, to provide an early warning about the potential risks of MNPs, many researchers have evaluated the current research on microplastics by means of the systematic assessment [47] of quality assurance/quality control and data quality [48]. Recently, there has been a large number of scientific reviews promising to elucidate not only the effects of MNP pollution on risks to human health [49] and the environment [50], but also many methodologies for the trace detection of MNPs in aquatic [51,52], sedimentary [53,54], freshwater, and coastal ecosystems [55], as well as other environments [56,57], in wastewater [58], and on beaches [59]. Furthermore, several researchers have investigated a variety of analytical technologies for the trace detection of MNPs, including fluorescence microscopy [18,[60][61][62], impedance spectroscopy [63], microwave-based techniques [64], hyperspectral imaging [65,66], Fourier transform infrared spectroscopy (FTIR) [67,68], near-infrared (NIR) hyperspectral imaging and chemometrics [69], semi-automated analysis [70], a thermo analytical method [71], and mass-or particlebased analysis [72]. ...
... Recently, MNP pollution has steadily become a crucial global issue due to the universal manufacture of MNPs and their use in plastic products [54,149]. Figure 4B illustrates rapid MNP detection using a novel substrate that was synthesized from plasmonic nanostructured materials-Au nanorods (AuNRs) and Ag nanowires (AgNWs)-applied to RC hydrogel films. The authors reported that the enhanced SERS signal of the crystal violet AgNWs/RC film was estimated to be approximately six times greater than that from AuNRs/RC film, which exhibited the SERS active array with a high enhanced factor of 10 7 . ...
Micro(nano)plastic (MNP) pollutants have not only impacted human health directly, but are also associated with numerous chemical contaminants that increase toxicity in the natural environment. Most recent research about increasing plastic pollutants in natural environments have focused on the toxic effects of MNPs in water, the atmosphere, and soil. The methodologies of MNP identification have been extensively developed for actual applications, but they still require further study, including on-site detection. This review article provides a comprehensive update on the facile detection of MNPs by Raman spectroscopy, which aims at early diagnosis of potential risks and human health impacts. In particular, Raman imaging and nanostructure-enhanced Raman scattering have emerged as effective analytical technologies for identifying MNPs in an environment. Here, the authors give an update on the latest advances in plasmonic nanostructured materials-assisted SERS substrates utilized for the detection of MNP particles present in environmental samples. Moreover, this work describes different plasmonic materials-including pure noble metal nanostructured materials and hybrid nanomaterials-that have been used to fabricate and develop SERS platforms to obtain the identifying MNP particles at low concentrations. Plasmonic nanostructure-enhanced materials consisting of pure noble metals and hybrid nanomaterials can significantly enhance the surface-enhanced Raman scattering (SERS) spectra signals of pollutant analytes due to their localized hot spots. This concise topical review also provides updates on recent developments and trends in MNP detection by means of SERS using a variety of unique materials, along with three-dimensional (3D) SERS substrates, nanopipettes, and microfluidic chips. A novel material-assisted spectral Raman technique and its effective application are also introduced for selective monitoring and trace detection of MNPs in indoor and outdoor environments.
Graphical abstract:
... For example, estimating mean MP concentrations at a given location requires accounting for the variability of MP concentrations over time with an adequate number of samples (Brander et al., 2020;Miller et al., 2021). Additional variability may be associated with sub-sampling of aliquots from those samples if they are not homogeneous throughout their containers (Abel et al., 2021). The preparation of aliquots can be associated with its own variability, especially in methods where only a subsample of the aliquot is actually used for analysis. ...
... Other steps taken by labs to minimize interferences may have compromised other metrics not evaluated in this study, such as decreased recoveries (bias) or subsampling imprecision prior to analysis, particularly for labs that split subsamples (Lab A) or subsampled only part of the aliquot (Labs A, C, and D). Depending on the final preparation step, low MP concentrations or buoyant MPs may cause a single subsample to be unrepresentative of the whole (Abel et al., 2021;Brandt et al., 2021). As such, preparing the entire sample but analyzing a fraction of the deposit may be a preferable alternative to preparing a fraction of the sample. ...
The need for improved microplastic (MP) data accuracy has been widely reported, but MP precision issues have been investigated less thoroughly. This work demonstrates how initial and continuing assessments of a laboratory's analytical precision can be used for establishing laboratory repeatability for MP analyses. These precision estimates can be reported along with MP results to ensure their quality and compare them meaningfully to other data. Re-analyses of reference MP samples can be used to assess and compare precision between different laboratories. A multi-lab precision exercise was demonstrated using infrared (IR) standard test methods performed on reference samples consisting of low-concentration MP spikes in both clean water and wastewater matrices. Each lab repeated their IR analyses 7 times and calculated relative standard deviations (RSD) for each detected polymer type using a standardized template. All labs' MP methods yielded generally repeatable results, though RSDs were consistently higher for lower MP counts. The reported range of total MP counts per sample was 8–33 particles, and the observed RSDs were 0.1–0.6. These RSDs were the same or lower than the expected imprecision due to random (Poisson) counting error alone, suggesting that these automated methods did not contribute any additional variability, and had slightly better reproducibility than expected for independent recounts. The wastewater matrix exhibited numerous interfering particles but did not yield more variability than the clean water matrix. The low-count design is a worst case for precision but is appropriate for some real-world sample concentrations. In practice, labs could generate separate references for precision assessment at multiple MP ranges (e.g., high, medium, and low.) The RSDs obtained from this data can be used to generate QC charts, detect changes in analyst performance, compare to Poisson error to identify additional sources of imprecision, and determine target filtration and instrumental parameters for MP analyses.
... In addition to these investigations of toxicity, to provide an early warning about the potential risks of MNPs, many researchers have evaluated the current research on microplastics by means of the systematic assessment [47] of quality assurance/quality control and data quality [48]. Recently, there has been a large number of scientific reviews promising to elucidate not only the effects of MNP pollution on risks to human health [49] and the environment [50], but also many methodologies for the trace detection of MNPs in aquatic [51,52], sedimentary [53,54], freshwater, and coastal ecosystems [55], as well as other environments [56,57], in wastewater [58], and on beaches [59]. Furthermore, several researchers have investigated a variety of analytical technologies for the trace detection of MNPs, including fluorescence microscopy [18,[60][61][62], impedance spectroscopy [63], microwave-based techniques [64], hyperspectral imaging [65,66], Fourier transform infrared spectroscopy (FTIR) [67,68], near-infrared (NIR) hyperspectral imaging and chemometrics [69], semi-automated analysis [70], a thermo analytical method [71], and mass-or particlebased analysis [72]. ...
... Recently, MNP pollution has steadily become a crucial global issue due to the universal manufacture of MNPs and their use in plastic products [54,149]. Figure 4B illustrates rapid MNP detection using a novel substrate that was synthesized from plasmonic nanostructured materials-Au nanorods (AuNRs) and Ag nanowires (AgNWs)-applied to RC hydrogel films. The authors reported that the enhanced SERS signal of the crystal violet AgNWs/RC film was estimated to be approximately six times greater than that from AuNRs/RC film, which exhibited the SERS active array with a high enhanced factor of 10 7 . ...
Micro(nano)plastic (MNP) pollutants have not only impacted human health directly, but are also associated with numerous
chemical contaminants that increase toxicity in the natural environment. Most recent research about increasing plastic pollutants in natural environments have focused on the toxic efects of MNPs in water, the atmosphere, and soil. The methodologies of MNP identifcation have been extensively developed for actual applications, but they still require further study,
including on-site detection. This review article provides a comprehensive update on the facile detection of MNPs by Raman
spectroscopy, which aims at early diagnosis of potential risks and human health impacts. In particular, Raman imaging and
nanostructure-enhanced Raman scattering have emerged as efective analytical technologies for identifying MNPs in an
environment. Here, the authors give an update on the latest advances in plasmonic nanostructured materials-assisted SERS
substrates utilized for the detection of MNP particles present in environmental samples. Moreover, this work describes different plasmonic materials—including pure noble metal nanostructured materials and hybrid nanomaterials—that have been
used to fabricate and develop SERS platforms to obtain the identifying MNP particles at low concentrations. Plasmonic
nanostructure-enhanced materials consisting of pure noble metals and hybrid nanomaterials can signifcantly enhance the
surface-enhanced Raman scattering (SERS) spectra signals of pollutant analytes due to their localized hot spots. This concise topical review also provides updates on recent developments and trends in MNP detection by means of SERS using a
variety of unique materials, along with three-dimensional (3D) SERS substrates, nanopipettes, and microfuidic chips. A
novel material-assisted spectral Raman technique and its efective application are also introduced for selective monitoring
and trace detection of MNPs in indoor and outdoor environments.
... Improper handling, inadequate waste management practices combined with the persistent and light-weight nature of plastic, have resulted in the widespread distribution of plastics worldwide (Jambeck et al., 2015). This global predicament extends to even the most secluded regions on earth, including the Arctic (Kanhai et al., 2018), Antarctica (Cincinelli et al., 2017), and the deepest oceanic realms (Abel et al., 2020;Peng et al., 2018), providing evidence of human impact even in isolated mountainous areas (Cabernard et al., 2018). Its diverse size and color spectrum, persistence, and varied chemical properties pose a significant threat to aquatic life directly exposed in their habitats (Cole et al., 2011;Moore, 2008) or indirect via the trophic transfer . ...
... For example, microplastics have been detected worldwide 90 and in human blood. 91 Microplastics and nanoplastics can alter the intestinal flora, potentially leading to diabetes, obesity, and chronic liver disease. 92 Water in plastic bottles often has higher concentrations of microplastics than processed tap water. ...
... MPs have been found even in the most remote marine habitats such as abyssal plains (Abel et al., 2021) and concentrations are likely to increase in next decades as pollution activities continue (Everaert et al., 2020). Their small size makes them accessible to a wide range of organisms through filtration or ingestion, accumulating through the food chain and threatening wildlife (Wright et al., 2013;Miller et al., 2020). ...
... The deep sea is considered a final sink for marine litter, including microplastic, as it will -if not subject to beaching -eventually sink down in the water column after colonization, biofilm formation or aggregation in marine snow and fecal pellets (Abel et al., 2021;Bergmann et al., 2017;Katija et al., 2017;Woodall et al., 2014). Furthermore, it has been suggested that microplastic can be transported from the surface to deeper water layers through ingestion and egestion by migratory species (Ferreira et al., 2022;Justino et al., 2022). ...
... These values are notably higher than those reported in the Kuril-Kamchatka trench (1.40 × 10-2.09 × 10 2 particles kg − 1 ; Abel et al., 2021) and the southern North Sea coastal sediments (3.00-1.19 × 10 3 particles kg − 1 ; Lorenz et al., 2019). ...
... A similar trend was also reported by other studies using the same automatic FPA-μFTIR microscopy and size class categories, not only in seawater samples Tekman et al., 2020) but also in other environmental matrices (e.g. sediment (Abel et al., 2021;Abel et al., 2022;Bergmann et al., 2017;Mani et al., 2019), sea ice cores (Peeken et al., 2018), and snow (Bergmann et al., 2019)). It is worth noting that in our study, the instrument has a lower detection limit of 11 μm. ...
... For instance, in the Southern North Sea, polypropylene was the most prevalent polymer in sediments . Similarly, a sediment core from Balearic Sea exhibited a high abundance of polypropylene and polyethylene alongside polystyrene (Simon-Sánchez et al., 2022).The abyssal and hadal sediments of the Kuril Kamchatka trench also showed a high prevalence of polypropylene (Abel et al., 2021).Additionally, polypropylene was ranked among the six most frequent polymers in the sediment from Byfjorden Fjord, Norway (Haave et al., 2019) and in sediment from the Fram Strait (Tekman et al., 2020). ...
... This environmental problem emerges as a direct outcome of both industrial and domestic operations, closely intertwined with the inadequate handling of plastics spanning from their production stages to eventual disposal [3]. Manifesting its impact across diverse ecosystems, from polar regions to uninhabited atolls and the depths of ocean basins, the pervasive presence of plastic pollution has escalated into a truly global concern [4][5][6]. Gradually, plastic waste disintegrates into smaller fragments, giving rise to the phenomenon termed as microplastics and nanoplastics. Regrettably, these particles can exert deleterious effects on animal life and pose a threat to the wellbeing of coastal communities. ...
... Microplastic con-Review of Scientific Instruments ARTICLE pubs.aip.org/aip/rsi tamination has been going on for decades and has been found in remote aquatic and terrestrial places such as the Kuril Kamchatka trench, 7 Mount Everest, 8 the oceans, and at the poles. 9 In the marine environment, microplastics are ingested by biota such as turtles, marine mammals, seabirds, and fish 10 and make their way through trophic transfer to humans, 2,11 where they may pose a health risk. ...
A horizontal water channel facility was built to study particle dynamics in a turbulent flow. The channel is sufficiently long to produce fully developed turbulence at the test section, and the width-to-height ratio is sufficiently large to avoid the sidewall effect for a large proportion of the cross-section. The system was designed to study the dynamics of complex-shaped particles in wall-bounded turbulence, the characteristics of which can be finely controlled. A maximum bulk velocity of up to 0.8 m s−1 can be achieved, corresponding to a bulk Reynolds number of up to 7 × 104 (shear Reynolds number ≈1580), and flow parameters can be controlled within ±0.1%. The transparent channel design and aluminum structures allow easy optical access, which enables multiple laser and camera arrangements. With the current optical setup, a measurement volume of up to 54 × 14 × 54 mm3 can be imaged and reconstructed with six cameras from the top, bottom, and sides of the channel. Finally, the in-house developed reconstruction and tracking procedure allows us to measure the full motion of complex objects (i.e., shape reconstruction, translational, and rotational motions), and in this instance, it is applied to the case of microscopic, non-isotropic polyamide fibers.
... They act as vital repositories for the accumulation of MPs, while concurrently providing habitats for an astonishing array of biodiversity on our planet. These sediments host a diverse spectrum of species, ranging from minute microscopic organisms to larger marine life forms (Abel et al., 2021;Yin, 2023). Research has furnished compelling evidence of MP uptake by marine species in both deep-sea and seafloor sediments, resulting in adverse effects on biodiversity (Bhagat et al., 2020;Ferreira et al., 2022;Justino et al., 2022;Yin, 2023). ...
Microplastics (MPs) have become prevalent in various environmental compartments, including air, water, and soil, attracting attention as significant pollutant parameters. This study investigated the prevalence of MP pollution in surface sediments along Istanbul's Marmara Sea, encompassing the megacity and the Bosphorus. A comprehensive sampling approach was employed, covering 43 stations across four seasons and depths ranging from 5 to 70 m. The objective was to assess the impact of terrestrial, social, and industrial activities on MPs. The average concentrations varied per season, with fall, winter, spring, and summer values recorded as 2000 ± 4100, 1600 ± 3900, 4300 ± 12,000, and 9500 ± 20,300 particles/kg-DW. The study identified river stations in the Golden Horn and sea discharge locations as hotspots for high concentrations. Notably, the dominant shape shifted from fibers in fall, winter, and spring to fragments during summer, coinciding with mucilage occurrences. The study identified 11 different polymers, with polyethylene (44 %) and polypropylene (31 %) being the most common.
... Although only two out of 53 samples from Svalbard beaches contained plastic particles ≥1 mm, this result supports the observation that meso-and microplastics have invaded the remotest places on Earth (Zhang et al., 2016;Evangeliou et al., 2020;Horton and Barnes, 2020;Napper et al., 2020;Trainic et al., 2020;Abel et al., 2021). The mean pollution levels in our samples could be the result of several conditions. ...
Plastic production and plastic waste have increased to such an extent that it has become globally ubiquitous. Recent research has highlighted that it has also invaded remote Polar Regions including the Arctic, where it is expected to accumulate over time due to transport from distant sources, rising local anthropogenic activities and increasing fragmentation of existing ocean plastics to microplastics (plastic items <5 mm). While a growing body of research has documented microplastics in the atmosphere, cryosphere, sea surface, water column, sediments and biota, contamination levels on Arctic beaches are poorly known. To fill this knowledge gap, we engaged citizen scientists participating in tourist cruises to sample beach sediments during shore visits on Svalbard, Norway. Following drying, sieving, and visual inspection of samples under a binocular microscope, putative plastic particles ≥1 mm were analysed by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Plastic particles ≥1 mm were found in two out of 53 samples from 23 beaches (mean: 196.3 particles kg⁻¹ and 147.4 particles L⁻¹). These pollution levels could be due to our focus on plastic particles ≥1 mm as well as the relatively small sample sizes used during this initial phase of the project. In addition, the coarse substrate on most beaches might retain fewer plastic particles. The two samples with plastic particles ≥1 mm contained six polyester-epoxide particles and 4920 polypropylene fibres. The latter likely originated from a fishing net and points to possibly accelerated plastic fragmentation processes on Arctic beaches. Since fisheries-related debris is an important source of plastic on Svalbard, a build-up of microplastic quantities can be expected to burden Arctic ecosystems in addition to climate change unless efficient upstream action is taken to combat plastic pollution.
... The massive production and extensive use of plastic followed by improper waste management have raised global concern. Plastic litter is widely distributed in various habitats, in which the coastal environment is one of the accumulation hotspots (Abel et al., 2021;Bergmann et al., 2017;Browne et al., 2011;Huang et al., 2021;Jamieson et al., 2019;Peng et al., 2020). Once released, the plastic litter is very likely to undergo fragmentation through either biodegradation or thermal-/photo oxidation (Wright et al., 2013). ...
This study examined microplastic (MP) occurrence and abundance in marine fish collected from the western and eastern waters of Hong Kong during the wet and dry seasons. Over half (57.1%) of the fish had MP in their gastrointestinal (GI) tracts, with overall MP abundance ranging from not detected to 44.0 items per individual. Statistical analysis revealed significant spatial and temporal differences in MP occurrence, with fish from more polluted areas having a higher likelihood of MP ingestion. Additionally, fish collected in the west during the wet season had significantly higher MP abundance, likely due to influence from the Pearl River Estuary. Omnivorous fish had significantly higher MP counts than carnivorous fish, regardless of collection location or time. Body length and weight were not significant predictors of MP occurrence or abundance. Our study identified several ecological drivers that affect MP ingestion by fish, including spatial-temporal variation, feeding mode, and feeding range. These findings provide a foundation for future research to investigate the relative importance of these factors in governing MP ingestion by fish in different ecosystems and species.
... Most microplastic particles found in the environment are created by fragmentation and weathering of plastic litter of any size (the so called 'secondary' microplastics), however 'primary' plastic particles such as microbeads and nurdles are also part of the total microlitter fraction (Leslie et al., 2017). Several studies have illustrated that they are widespread, as they have been found at both the highest (e.g., Mount Everest) and deepest points on Earth, namely the deep sea (Abel et al., 2021;Napper et al., 2020;Van Cauwenberghe et al., 2013). At the start of this study in 2018, efforts from the scientific community primarily focused on MP distribution in the marine environment, and <4 % of microplastics-related studies were conducted in freshwater systems (Lambert and Wagner, 2018). ...
Microplastics (MPs) are an emerging pollutant of concern in all known aquatic ecosystems. However, studies at a regional scale on MP pollution in freshwater systems and the necessary risk assessments are limited. Therefore, in this study, we examined microplastic concentrations, size distributions, and polymer types in surface waters and sediments in the geographic region Flanders (Belgium), as a case study for a densely populated region and one of the most developed parts of Europe. Samples have been taken on nine different locations, of which five were repeated in a different weather condition. In total 43 aqueous and nine sediment samples have been collected. The quantity and identity of the microplastics in the samples were determined with μFTIR spectroscopy in the range of 25-1000 μm. The MPs' abundances in surface waters and sediments ranged from 0 to 4.8 MP L-1 (average = 0.48 MP L-1) and from 0 to 9558 MP kg-1 dry weight (average = 2774.57 ± 2317.93 MP kg-1 DW), respectively. Polystyrene and polypropylene were the most common polymer compositions found. No correlations were observed between microplastic concentrations in the sediment/the surface water samples and the measured environmental variables rainfall, conductivity, pH, dissolved oxygen content, waterway flow rate and width, and surrounding land use. Risk assessment results for the measured surface water concentrations through the risk quotient (RQ) method and the probabilistic risk assessment framework suggest that most of the sampled sites in Flanders posed negligible risks to freshwater biota, while this was not the case for some of the sediment concentrations. Our results illustrate the need to urgently develop analytical methods that can routinely measure the full size range of MP in environmental samples to adequately assess risks for the environment.
... However, the focus of microplastics research to date has largely been on the marine realm with relatively few studies focusing on terrestrial environments . Of late, microplastics have been reported in more remote locations stretching from the very bottom of the ocean to the top of mount Everest (Abel et al., 2021;Napper et al., 2020). ...
Microplastics are an environmental issue of global concern. Although they have been found in a range of environments worldwide, their contamination in the terrestrial environment is poorly understood, particularly in relation to their source and fate. One source of microplastics in soils of particular concern is biosolids. Biosolids are the solid by-product of the wastewater treatment and are commonly spread on agricultural land as a fertilizer, indicating a potential route for microplastics into terrestrial soils. The aim of this thesis was therefore to broaden the understanding of microplastic contamination in agricultural soils in relation to biosolid application. The lack of suitable methods for microplastic detection and quantification is a major obstacle for determining their concentrations in soil environments. Therefore, an experiment was carried out to determine the best methods for microplastic extraction based on soil characteristics. The efficiency of organic matter removal methods was measured. Soils with a range of particle size distribution and organic matter content were spiked with a variety of microplastic types and density separation methods were tested. The optimal organic removal method was found to be hydrogen peroxide with organic removal rates up to 93%. The recovery efficiency of microplastics was variable across polymer types. Overall, canola oil was shown to be the best method for density separation, however, efficiency was dependent on the amount of organic matter in the soil. This outcome highlights the importance of including matrix-specific calibration in future studies considering a wide range of microplastic types, to avoid underestimation of microplastic contamination. To understand the sources and fate of microplastics in agricultural soils, these tailored methods were used to extract microplastics from samples collected from agricultural soils in the River Test catchment area in the UK. Soils were collected from fields which had historical biosolid application and these were compared to a similar set of fields which had never received biosolid application during summer and winter. The mean microplastic concentration was high in both the biosolid treated fields (874 MP/kg) and the untreated fields (664 MP/kg) and a wide variety of polymers were found across sites. There was a lack of significant difference between treated and untreated soils suggesting the influence of other sources and environmental processes. Additionally, soil samples were collected from five separate fields over the course of a year, before and after biosolid application. Microplastic contamination was ubiquitous across these fields up to a maximum concentration of 7950 MP/kg. Despite previous reports of high concentrations of microplastics in biosolids, their concentrations in soils did not significantly increase after application of biosolids. This suggests that biosolids may not be the key influencing factor in microplastic soil concentrations and transport out of soil systems is likely through horizontal (run off) and lateral (percolation) routes. Agricultural soils may thus be acting as a vector for microplastics to freshwater systems and the wider environment. Overall, the results of this thesis suggest that biosolids, whilst are likely a contributor, are not the sole source of microplastics in agricultural soils. The importance of additional sources and pathways are explored, and the complexities of the soil environment are considered, suggesting the highly dynamic nature of soil environment may determine the variability in microplastic concentrations. The research presented here significantly increased the understanding of microplastic sources and fate in agricultural soil systems while highlighting directions for future soil microplastic research.
... Video footage from the remotely operated vehicle (ROV) Holland 1 based on video transects of the macrofauna present within the habitat 38 also recorded macroplastic pollution in the form of large plastic items, fishing nets, and abandoned, lost, or discarded fishing gear, at 10 stations (for Figure S1). Of these, 50% were recorded from the GSDB (1,4,6,8,9), one station within each of the BMP SAC (16), GS (29), and KP (19), and two within the GCS (27, 28). Furthermore, a discarded corroded oil drum was recorded within the latter system at station 31. ...
Microplastics are ubiquitous emerging contaminants found in every habitat surveyed, building upon international databases globally. Costs and accessibility often correlate to few deep sea sediment surveys, restricting the number of stations within a given sampling area. An extensive survey of the Porcupine Seabight, Porcupine Bank, the Goban Spur, and south-western canyons resulted in identifying microplastics in deep sea sediment surface layers from 33 of the 44 stations sampled (75%), with a total of 83 particles (74 synthetic and 9 natural) recorded. No microplastic hotspots were identified, and abundances (kg d.w.-1) were not correlated with distance from land, depth, or the presence of macrolitter on the seafloor. Understanding the sources of deep sea microplastics, such as marine traffic, is crucial to developing effective mitigation strategies as well as further monitoring campaigns targeting microplastic pollution in areas with significant deep sea biodiversity such as the Porcupine Seabright.
... Automated particle-based analysis was performed at the Biological Institute Helgoland (BAH) of the Alfred Wegner Institute, Helmholtz Centre for Polar and Marine Research, Germany, following a well-established protocol (Primpke et al., 2018). Purified samples were submitted to a second density separation and digestion steps (Abel et al., 2021) to disaggregate flocculates and eliminate potential biofilm immediately before micro-Fourier transform infrared spectroscopic analysis (µFTIR; Hyperion 3000m, Bunker Optics GmbH). This technique measured 100% of remaining particles in each sample to ensure all potential MP particles could be associated to a specific polymer type, or excluded from being classified as plastic. ...
The short sediment core EMB201/7-4 retrieved from the East Gotland Basin, central Baltic Sea, is explored here as a candidate to host the stratigraphical basis for the Anthropocene series and its equivalent Anthropocene epoch, still to be formalized in the Geological Time Scale. The core has been accurately dated back to 1840 CE using a well-established event stratigraphy approach. A pronounced and significant change occurs at 26.5 cm (dated 1956 ± 4 CE) for a range of geochemical markers including ²³⁹⁺²⁴⁰ Pu, ²⁴¹ Am, fly-ash particles, DDT (organochlorine insecticide), total organic carbon, and bulk organic carbon stable isotopes. This stratigraphic level, which corresponds to a change in both lithology and sediment colour related to early anthropogenic-triggered eutrophication of the central Baltic Sea, is proposed as a Global Boundary Stratotype Section and Point for the Anthropocene series.
... Up to now, most studies have focused on MPs in surface waters but, even if many plastic polymers are buoyant, MPs destiny in the marine environment is to sink into the sediments after biofouling or incorporation in marine snow or fecal pellets, accumulating in the benthos and coastal areas, especially sandy beaches (Kooi et al., 2017;Michels et al., 2018;Wright et al., 2020;Reinold et al., 2021). Indeed, MPs lighter than seawater have been found even in deep-sea sediments (Cunningham et al., 2020;Abel et al., 2021;Cutroneo et al., 2022). MPs buried in sediments encounter different microbial communities and biogeochemical contexts, with respect to the water column, that affect the colonization dynamics and the composition of the resulting MPs-associated biofilm (Rogers et al., 2020;Wright et al., 2021). ...
Plastic debris dispersed into the environment provide a substrate for microbial colonization, constituting a new human-made ecosystem called "plastisphere", and altering the microbial species distribution in aquatic, coastal and benthic ecosystems. The study aims at exploring the interaction among microplastics (MPs) made of different polymers, a persistent organic contaminant (polychlorinated biphenyls, PCBs), and the environmental microbial communities, in an anoxic marine sediment. Plastic pellets were incubated in the field in a salt marsh anoxic sediment, to observe the stages of plastisphere formation, by quantitative PCR and 16S rRNA gene sequencing, and PCB dechlorination activity on the MPs surface. Microbes from the sediment rapidly colonized the different microplastics types, with PVC recruiting a peculiar community enriched in sulfate-reducing bacteria. The composition of the plastisphere varied along the 1-year incubation possibly in response either to warmer temperatures in spring-summer or to microhabitat's changes due to the progressive plastic surface weathering. Even if PCB contaminated MPs were able to recruit potentially dehalogenating taxa, actual dechlorination was not detectable after 1 year. This suggests that the concentration of potentially dehalorespiring bacteria in the natural environment could be too low for the onset of the dechlorination process on MP-sorbed contaminants. Our study, which is among very few available longitudinally exploring the plastisphere composition in an anoxic sediment context, is the first exploring the fate and possible biodegradation of persistent organic pollutants sorbed on MPs reaching the seafloor.
... Microplastics have been found in a wide array of aquatic environments, from pristine mountain streams to the Arctic [23] to deep undersea habitats [1]. Toxicological studies have determined microplastics can cause adverse effects, such as tissue inflammation [50], impaired growth [71], feeding disruption [62], developmental anomalies [21], and changes in gene expression [69]. ...
Assessing microplastics risk to aquatic ecosystems has been limited by lack of holistic exposure data and poor understanding of biological response thresholds. Here we take advantage of two recent advances, a toxicological meta-analysis that produced biotic response thresholds and a method to quantitatively correct exposure data for sampling methodology biases, to assess microplastic exposure risk in San Francisco Bay, California, USA. Using compartment-specific particle size abundance data, we rescaled empirical surface water monitoring data obtained from manta trawls (> 333 μm) to a broader size (1 to 5000 μm) range, corrected for biases in fiber undercounting and spectroscopic subsampling, and assessed the introduced uncertainty using probabilistic methods. We then compared these rescaled concentrations to four risk thresholds developed to inform risk management for California for each of two effect categories/mechanisms - tissue translocation-mediated effects and food dilution - each aligned to ecologically relevant dose metrics of surface area and volume, respectively. More than three-quarters of samples exceeded the most conservative food dilution threshold, which rose to 85% when considering just the Central Bay. Within the Central Bay, 38% of the samples exceeded a higher threshold associated with management planning, which was statistically significant at the 95% confidence interval. For tissue translocation-mediated effects, no samples exceeded any threshold with statistical significance. The risk associated with food dilution is higher than that found in other systems, which likely reflects this study having been conducted for an enclosed water body. A sensitivity analysis indicated that the largest contributor to assessment variability was associated with estimation of ambient concentration exposure due to correcting for fiber undercounting. Even after compensating for biases associated with fibers and other small particles, concentrations from the trawl samples were still significantly lower than the 1-L grab samples taken at the same time, suggesting our SFB risk estimates are an underestimate. We chose to rely on the trawl data because the 1-L grab sample volume was too small to provide accurate spatial representation, but future risk characterization studies would be improved by using in-line filtration pumps that sample larger volumes while capturing a fuller range of particle size than a towed net.
... In the context of monitoring, either of these approaches is considered sufficient for determining the total number of plastic particles in a sample. Splitting the sample prior to chemical analysis is another way to reduce analytical costs, although this can only be performed during sample handling in the laboratory and may induce risks such as missing polymer types or over/underestimating the total load of microplastics (Abel et al. 2021). ...
The pollution of the environment with plastics is of growing concern worldwide, including the Arctic region. While larger plastic pieces are a visible pollution issue, smaller microplastics are not visible with the naked eye. These particles are available for interaction by Arctic biota and have become a concern for animal and human health. The determination of microplastic properties includes several methodological steps, i.e., sampling, extraction, quantification, and chemical identification. This review discusses suitable analytical tools for the identification, quantification, and characterization of microplastics in the context of monitoring in the Arctic. It further addresses quality assurance and quality control (QA/QC), which is particularly important for the determination of microplastic in the Arctic, as both contamination and analyte losses can occur. It presents specific QA/QC measures for sampling procedures and for the handling of samples in the laboratory, either on land or on ship, and considering the small size of microplastics as well as the high risk of contamination. The review depicts which data should be mandatory to report, thereby supporting a framework for harmonized data reporting.
... Critical to the discussion of microplastics in the Arctic is the movement of water masses through the region, as well as the distributions of different kinds of sedimentary environments. Litter and microplastics can be transported within water bodies from point sources such as wastewater outlets to nearshore and offshore areas, and settle in shoreline sediment, beach sand, shoreline gravel, and benthic zones including the deep-ocean floor (Lots et al. 2017;Bosker et al. 2018;Piñon-Colin et al. 2018;Abel et al. 2021). The Arctic Monitoring and Assessment Programme (AMAP) region covers 18 large marine ecosystems, influenced by several marine current systems and hundreds of freshwater rivers ( Fig. 1) (Protection of the Arctic Marine Environment Working Group (PAME) 2013a, 2013b). ...
Litter and microplastic assessments are being carried out worldwide. Arctic ecosystems are no exception and plastic pollution is high on the Arctic Council's agenda. Water and sediment have been identified as two of the priority compartments for monitoring plastics under the Arctic Monitoring and Assessment Programme (AMAP). Recommendations for monitoring both compartments are presented in this publication. Alone, such samples can provide information on presence, fate, and potential impacts to ecosystems. Together, the quantification of microplastics in sediment and water from the same region produce a three-dimensional picture of plastics, not only a snapshot of floating or buoyant plastics in the surface water or water column but also a picture of the plastics reaching the shoreline or benthic sediments, in lakes, rivers, and the ocean. Assessment methodologies must be adapted to the ecosystems of interest to generate reliable data. In its current form, published data on plastic pollution in the Arctic is sporadic and collected using a wide spectrum of methods which limits the extent to which data can be compared. A harmonised and coordinated effort is needed to gather data on plastic pollution for the Pan-Arctic. Such information will aid in identifying priority regions and focusing mitigation efforts.
... Microplastic particles (MPs; < 5000 μm) are pervasive in the aquatic environment, including ocean surface waters [54], deep ocean trenches [1], wetlands [36], lakes [13,14] and the Arctic [20]. Exposure to MPs has been associated with various types of biological responses, including disruption of feeding [61], decreases in growth [48], tissue inflammation [43], changes in gene expression [42,66], and decreases in reproductive success [55]. ...
Microplastic particles (MPs) are ubiquitous across a wide range of aquatic habitats but determining an appropriate level of risk management is hindered by a poor understanding of environmental risk. Here, we introduce a risk management framework for aquatic ecosystems that identifies four critical management thresholds, ranging from low regulatory concern to the highest level of concern where pollution control measures could be introduced to mitigate environmental emissions. The four thresholds were derived using a species sensitivity distribution (SSD) approach and the best available data from the peer-reviewed literature. This included a total of 290 data points extracted from 21 peer-reviewed microplastic toxicity studies meeting a minimal set of pre-defined quality criteria. The meta-analysis resulted in the development of critical thresholds for two effects mechanisms: food dilution with thresholds ranging from ~ 0.5 to 35 particles/L, and tissue translocation with thresholds ranging from ~ 60 to 4100 particles/L. This project was completed within an expert working group, which assigned high confidence to the management framework and associated analytical approach for developing thresholds, and very low to high confidence in the numerical thresholds. Consequently, several research recommendations are presented, which would strengthen confidence in quantifying threshold values for use in risk assessment and management. These recommendations include a need for high quality toxicity tests, and for an improved understanding of the mechanisms of action to better establish links to ecologically relevant adverse effects.
... Microplastics have been found in a wide array of aquatic environments, from pristine mountain streams to the Arctic (Gonzalez-Pleiter et al. 2020) to deep undersea habitats (Abel et al. 2021). Toxicological studies have determined microplastics can cause adverse effects, such as tissue inflammation ( Quantifying the risk of microplastics in aquatic ecosystems is challenging for two reasons. ...
Assessing microplastics risk to aquatic ecosystems has been limited by lack of holistic exposure data and poor understanding of biological response thresholds. Here we take advantage of two recent advances, a toxicological meta-analysis that produced biotic response thresholds and a method to quantitatively correct exposure data for sampling methodology biases, to assess microplastic exposure risk in San Francisco Bay, California, USA. Using compartment-specific particle size abundance data, we rescaled empirical surface water monitoring data obtained from manta trawls (> 333 µm) to a broader size (1 to 5,000 µm) range, corrected for biases in fiber undercounting and spectroscopic subsampling, and assessed the introduced uncertainty using probabilistic methods. We then compared these rescaled concentrations to four risk thresholds developed to inform risk management for California for each of two effect categories/mechanisms - tissue translocation-mediated effects and food dilution - each aligned to ecologically relevant dose metrics of surface area and volume, respectively. More than three-quarters of samples exceeded the most conservative food dilution threshold, which rose to 85% when considering just the Central Bay. Within the Central Bay, 38% of the samples exceeded a higher threshold associated with management planning, which was statistically significant at the 95% confidence interval. For tissue translocation-mediated effects, no samples exceeded any threshold with statistical significance. The risk associated with food dilution is higher than that found in other systems, which likely reflects this study having been conducted for an enclosed water body. A sensitivity analysis indicated that the largest contributor to assessment variability was associated with estimation of ambient concentration exposure due to correcting for fiber undercounting. Even after compensating for biases associated with fibers and other small particles, concentrations from the trawl samples were still significantly lower than the 1-L grab samples taken at the same time, suggesting our SFB risk estimates are an underestimate. We chose to rely on the trawl data because the 1-L grab sample volume was too small to provide accurate spatial representation, but future risk characterization studies would be improved by using in-line filtration pumps that sample larger volumes while capturing a fuller range of particle size than a towed net.
In this review, we discussed and compared the applications of Fourier transform infrared spectroscopy, quantum cascade laser infrared spectroscopy, atomic force microscopy-based infrared spectroscopy, and optical photothermal infrared spectroscopy in MNP research from multiple perspectives.
Although most deep-sea areas are remote in comparison to coastal zones, a growing body of literature indicates that many sensitive ecosystems could be under increased stress from anthropogenic sources. Among the multiple potential stressors, microplastics (MPs), pharmaceuticals and personal care products (PPCPs/PCPs) and the imminent start of commercial deep-sea mining have received increased attention. Here we review the recent literature on these emerging stressors in deep-sea environments and discuss the cumulative effects with climate change associated variables. Importantly, MPs and PPCPs have been detected in deep-sea waters, organisms and sediments, in some locations in comparable levels to coastal areas. The Atlantic Ocean and the Mediterranean Sea are the most studied areas and where higher levels of MPs and PPCPs have been detected. The paucity of data for most other deep-sea ecosystems indicates that many more locations are likely to be contaminated by these emerging stressors, but the absence of studies hampers a better assessment of the potential risk. The main knowledge gaps in the field are identified and discussed, and future research priorities are highlighted to improve hazard and risk assessment.
Due to its ever-increasing ocean inputs, fossil-based microplastics (MP) comprise a considerable constituent in the particulate organic carbon (POC) pool, which is instrumental in ocean biogeochemical cycling. Their distribution within the oceanic water column and the underpinning processes, however, remain unclear. Here we show that MP prevail throughout the water column of the eastern North Pacific subtropical gyre, comprising 334 #/m3 (84.5% of plastic particles <100 μm), with exponential relationships between concentrations and water depth in the upper 500-m layer and marked accumulation below this layer. Our results suggest that the biological carbon pump (BCP) strongly contributes to the water-column MP redistribution in terms of polymer type, material density and particle size, which in turn could influence the efficiency of organic matter export to the deep sea. We further show that 14C-depleted plastic particles predictably are an emerging non-neglectable perturbation to radiocarbon signatures in the deep ocean through depletion of the 14C/C ratio in the POC pool. Our data provide insight into vertical MP flux and highlight the potential role of MP in alternating the marine particulate pool and interactions with the BCP.
The occurrence of microplastics (MPs) pollution in sediments has brought huge challenges to the development of society. Pollution control of MPs in sediments has become an inevitable requirement for current society. This requires implementing targeted pollution control measures in high MPs ecological risk areas and controls MPs discharge in pollution source. Existing studies lack in-depth understanding in MPs ecological risk assessment and MPs pollution source analysis, this limits the pollution control of MPs in sediments. In this study, the studies of MPs pollution in sediments from 2013 to 2022 were reviewed. The results showed that the environmental problems caused by MPs pollution in marine sediments have been widely discussed over the past decade. And the occurrence of MPs pollution in sediments brought potential threat to marine ecology and human food supply. Furthermore, pollution load index, polymer risk index and potential ecological risk index of MPs were frequently used in the existing ecological risk assessment of MPs in sediments. A large amount of monitoring data and simulation data is conducive to improving these MPs ecological risk assessment indicators. This can provide a useful reference for managers to formulate MPs pollution control measures. And MPs types and land-use types can provide basis to analyze the pollution source of MPs in sediments. Developing more accurate MPs detection and analysis technologies can further improve current MPs pollution source analysis system. This is conducive to control the discharge of MPs in the pollution source. In future studies, more complete MPs ecological risk assessment system and MPs pollution source analysis system should be established to control the pollution of MPs in sediments.
The seafloor is the major sink for microplastic (MP) pollutants. However, there is a lack of robust data on the historical evolution of MP pollution in the sediment compartment, particularly the sequestration and burial rate of small MPs. By combining a palaeoceanographic approach and state-of-the-art analytical methods for MP identification down to 11 μm in size, we present the first high-resolution reconstruction of MP pollution from an undisturbed sediment core collected in the NW Mediterranean Sea. Furthermore, we investigate the fate of MPs once buried in the sediments by evaluating the changes in the size distribution of the MPs and the weathering status of the polyolefins, polyethylene, and polypropylene. Our results indicate that the MP mass sequestered in the sediment compartment mimics the global plastic production from 1965 to 2016. We observed an increase in the weathering status of the polyolefins as the size decreased. However, the variability in the size and weathering status of the MPs throughout the sedimentary record indicated that these pollutants, once incorporated into sediments, remain preserved with no further degradation under conditions lacking remobilization.
An increasing number of methods for extracting microplastic particles from marine sediments have been published but without evaluating the extraction efficiency. Furthermore, while most of the procedures developed have been applied to sandy sediments from shallow water habitats, specific and standardized procedures for deep-water sediments (> 200 meters deep) are limited. In this study, we describe a specific protocol for extracting microplastics (2- 1000 µm) from deep-sea sediments and for quantifying and identifying them. We also assessed its extraction efficiency, which resulted in a high recovery (on average ca. 60%, and up to 80%) particularly, for polyethylene, polypropylene, and polystyrene. This method can be applied to all fine-grained/muddy sediments and allows the extraction of even the smallest fraction of microplastics (<20 µm), which are expected to have the most severe effects on marine biodiversity and ecosystem functioning and ultimately also have implications for human health.
Microplastics have attracted worldwide attention due to their potential threat to the marine ecosystem, with such pollutants even detected in the polar seas. Although in-depth research on microplastics has increased in recent years, studies in Antarctic waters remain relatively scarce compared with coastal waters and open oceans. In this study, microplastics in surface and subsurface Antarctic waters were investigated. The average microplastic abundance in the surface water was 0.10 ± 0.14 items/m³, with highest abundance in the Ross Sea, and the average microplastic abundance in the subsurface water was 1.66 ± 1.20 items/m³, with highest abundance in the Dumont d'Urville Sea. Polyester was the main microplastic in the surface waters (87.3%), while polypropylene (33.1%), polyester (28.7%), and polyethylene (22.8%) were the dominant microplastics in the subsurface waters. Results indicate that microplastic pollution in Antarctic waters may come from the Antarctic continent as well as southward transport from the ocean at mid- and low latitudes.
The polar plastics research community have recommended the spatial coverage of microplastic investigations in Antarctica and the Southern Ocean be increased. Presented here is a baseline estimate of microplastics in the nearshore waters of South Georgia, the first in situ study of the north-east coast of the island. Our results show that the microplastic concentration in seawater at twelve stations in proximity to King Edward Point Research Station ranged from 1.75 ± 5.17 MP/L (mean ± SD), approximately one order of magnitude higher than similar studies of sea surface waters south of the Polar Front. Levels of microplastics in freshwater (sampled from Gull Lake) and precipitation (collected adjacent to the research station) were 2.67 ± 3.05 MP/L, and 4.67 ± 3.21 MP/L respectively. There was no significant difference in the microplastic concentration between seawater sites, and no significant bilateral relationship between concentration and distance from the research station outlets. We report an average concentration of 1.66 ± 3.00 MP/L in wastewater collected from the research station but overall, the counts of microplastics were too low to attach any statistical significance to the similarity in the microplastic assemblages of seawater and wastewater, or assemblages retrieved from penguin species in the region in other studies. Using a calculation described in contemporary literature we estimate the number of microfibres potentially being released from ships and stations annually in the region but acknowledge that further samples are needed to support the figures generated. More extensive research into microplastic distribution, characteristics, and transport in the region is recommended to fully compute the level of risk which this pollutant represents to the ecosystem health of this remote region.
Microplastics (MP) are of major concerns for the society and currently in the focus of legislators and administrations. A small number of measures to reduce or remove primary sources of MP to the environment are currently coming into effect. At the moment, they have not yet tackled important topics such as food safety. However, recent developments such as the 2018 bill in California are requesting the analysis of MP in drinking water by standardized operational protocols (SOP). Administrations and analytical labs are facing an emerging field of methods for sampling, extraction, and analysis of MP, which complicate the establishment of SOPs. In this review the state of the currently applied identification and quantification tools for MP are evaluated providing a harmonized guideline for future SOPs to cover these types of bills. The main focus is on the naked eye detection, general optical microscopy, the application of dye staining, flow cytometry, Fourier transform infrared (FT-IR) spectroscopy and microscopy, Raman spectroscopy and microscopy and thermal degradation by pyrolysis-gas chromatography-mass spectrometry (py-GC-MS) as well as thermo-extraction and desorption gas chromatography-mass spectrometry (TED-GC-MS). Additional techniques are highlighted as well as the combined application of the analytical techniques suggested. An outlook is given on the emerging aspect of nanoplastic analysis. In all cases, the methods were screened for limitations, field work abilities and, if possible, estimated costs and summarized into a recommendation for a workflow covering the demands of society, legislation, and administration in cost efficient but still detailed manner.
Microplastics (MP) are ubiquitous within the environment, but the analysis of this contaminant is
currently quite diverse, and a number of analytical methods are available. The comparability of
results is hindered as even for a single analytical method such as Fourier transform infrared
spectroscopy (FT-IR) the different instruments currently available do not allow a harmonized
analysis. To overcome this limitation, a new free of charge software tool, allowing the systematic
identification of MP in the environment (siMPle) was developed. This software tool allows a
rapid and harmonized analysis of MP across FT-IR systems from different manufacturers
(Bruker Hyperion 3000, Agilent Cary 620/670, PerkinElmer Spotlight 400, Thermo Fischer
Scientific Nicolet iN10). Using the same database and the automated analysis pipeline (AAP) in
siMPle, MP were identified in samples that were analyzed with instruments with different
detector systems and optical resolutions, the results of which are discussed.
Recent studies have shown that despite its remoteness, the Arctic region harbors some of the highest microplastic (MP) concentrations worldwide. Here, we present the results of a sampling campaign to assess the vertical distribution of MP particles (>11 µm) at five stations of the HAUSGARTEN observatory. Water column samples were taken with large volume pumps by filtering 218 – 561 liters of seawater at two to four depth strata (near-surface, ~300 m, ~1000 m and above seafloor) and sediment samples with a multiple corer. MP concentrations in the water column ranged between 0 – 1,287 N m⁻³ and in the sediment from 239 – 13,331 N kg⁻¹. Fourier transform infrared spectroscopy (FTIR) imaging with automated data analysis showed that polyamide (39%) and ethylene-propylene-diene rubber (23%) were the most abundant polymers within the water samples and polyethylene-chlorinated (31%) in sediments. MPs ≤25 µm accounted for more than half of the synthetic particles in every sample. The largest MP particle recorded was in the 200 µm size class. The concentrations of fibers were not reported, as fiber detection by FTIR imaging was not available at the time of analyses. Two- and three-dimensional simulations of particle transport trajectories suggest different pathways for certain polymer types. A positive correlation between MP size composition and particulate organic carbon indicates interactions with biological processes in the water column.
Microplastics (< 5 mm) have long been a concern in marine debris research, but quantifying the smallest microplastics (< 333 μm) has been hampered by appropriate collection methods, like net tows. We modified standard epifluorescence microscopy methods to develop a new technique to enumerate < 333 μm microplastics (mini‐microplastics) from filtered surface seawater samples and salp stomach contents. This permitted us to distinguish mini‐microplastics from phytoplankton and suspended particles. We found seawater mini‐microplastic concentrations that were 5–7 orders of magnitude higher than published concentrations of > 333 μm microplastics. Mini‐microplastics were the most abundant in nearshore waters and more evenly distributed from the California Current through the North Pacific Subtropical Gyre. Every salp examined had ingested mini‐microplastics, regardless of species, life history stage, or oceanic region. Salps ingested significantly smaller plastic particles than were available in ambient surface seawater. The blastozooid stage of salps had higher ingestion rates than oozooids.
The deep‐sea benthos covers over 90% of seafloor area and hosts a great diversity of species which contribute toward essential ecosystem services. Evidence suggests that deep‐seafloor assemblages are structured predominantly by their physical environment, yet knowledge of assemblage/environment relationships is limited. Here, we utilized a very large dataset of Northwest Atlantic Ocean continental slope peracarid crustacean assemblages as a case study to investigate the environmental drivers of deep‐seafloor macrofaunal biodiversity. We investigated biodiversity from a phylogenetic, functional, and taxonomic perspective, and found that a wide variety of environmental drivers, including food availability, physical disturbance (bottom trawling), current speed, sediment characteristics, topographic heterogeneity, and temperature (in order of relative importance), significantly influenced peracarid biodiversity. We also found deep‐water peracarid assemblages to vary seasonally and interannually. Contrary to prevailing theory on the drivers of deep‐seafloor diversity, we found high topographic heterogeneity (at the hundreds to thousands of meter scale) to negatively influence assemblage diversity, while broadscale sediment characteristics (i.e., percent sand content) were found to influence assemblages more than sediment particle‐size diversity. However, our results support other paradigms of deep‐seafloor biodiversity, including that assemblages may vary inter‐ and intra‐annually, and how assemblages respond to changes in current speed. We found that bottom trawling negatively affects the evenness and diversity of deep‐sea soft‐sediment peracarid assemblages, but that predicted changes in ocean temperature as a result of climate change may not strongly influence continental slope biodiversity over human timescales, although it may alter deep‐sea community biomass. Finally, we emphasize the value of analyzing multiple metrics of biodiversity and call for researchers to consider an expanded definition of biodiversity in future investigations of deep‐ocean life. We utilize a very large dataset of Northwest Atlantic Ocean peracarid crustacean assemblages as a case study to investigate the environmental drivers of deep‐seafloor macrofaunal biodiversity. We investigate biodiversity from a phylogenetic, functional, and taxonomic perspective, and find food availability, physical disturbance (bottom trawling), current speed, sediment characteristics, topographic heterogeneity, and temperature to significantly influence peracarid biodiversity (in order of relative importance). Our results both challenge and lend support to paradigms of deep‐seafloor biodiversity. We emphasize the value of analyzing multiple metrics of biodiversity and call for researchers to consider an expanded definition of biodiversity in future investigations of deep‐ocean life.
The study area is focused on the Kuril-Kamchatka Trench, North Paciic Ocean. This region is geologically complex, notable for the lithosphere activity, tectonic plates subduction and active volcanism. The submarine geomorphology is complicated through terraces, slopes, seamounts and erosional processes. Understanding geomorphic features of such a region requires precise modelling and effective visualization of the high-resolution data sets. Therefore, current research presents a Generic Mapping Tools (GMT) based algorithm proposing a solution for effective data processing and precise mapping: iterative module-based scripting for the automated digitizing and modelling. Methodology consists of the following steps: topographic mapping of the raster grids, marine gravity and geoid; semi-automatic digitizing of the orthogonal cross-section profiles; modelling geomorphic trends of the gradient slopes; computing raster surfaces from the xyz data sets by modules nearneighbor and XYZ2grd. Several types of the cartographic projections were used: oblique Mercator, Mercator cylindrical, conic equal-area Albers, conic equidistant. The cross-section geomorphic profiles in a perpendicular direction across the two selected segments of the trench were automatically digitized. Developed algorithm of the semi-automated digitizing of the profiles enabled to visualize gradients of the slope steepness of the trench. The data were then modelled to show gradient variations in its two segments. The results of the comparative geomorphic analysis of northern and southern transects revealed variations in different parts of the trench. Presented research provided more quantitative insights into the structure and settings of the submarine landforms of the hadal trench that still remains a question for the marine geology. The research demonstrated the effectiveness of the GMT: a variety of modules, approaches and tools that can be used to produce high-quality mapping and graphics. The GMT listings are provided for repeatability.
The book cites data on the fauna in deep-sea trenches and demonstrates the conditions for existence in them of deep-sea organisms. It correlates information regarding all the biological research conducted by Soviet and foreign expeditions from 1875 to 1985. Complete lists are given of the animals (from Protozoa to fish) that are known from depths over 6 km, over 800 species with an indication of their habitat depth and geographical dissemination. The unique nature of the animal world in the trenches, the reasons for its originality, questions of the evolution and origin of the trench fauna, and data on its zoogeographical zoning are discussed. Translation financially arranged by Peter Brueggeman, who then assembled the translation document and OCRed it.
An estimated 8.3 billion tons of non-biodegradable plastic has been produced over the last 65 years. Much of this is not recycled and is disposed into the natural environment, has a long environmental residence time and accumulates in sedimentary systems worldwide, posing a threat to important ecosystems and potentially human health. We synthesize existing knowledge of seafloor microplastic distribution, and integrate this with process-based sedimentological models of particle transport, to provide new insights, and critically, to identify future research challenges. Compilation of published data shows that microplastics pervade the global seafloor, from abyssal plains to submarine canyons and deep-sea trenches (where they are most concentrated). However, few studies relate microplastic accumulation to sediment transport and deposition. Microplastics may enter directly into the sea as marine litter from shipping and fishing, or indirectly via fluvial and aeolian systems from terrestrial environments. The nature of the entry-point is critical to how terrestrially sourced microplastics are transferred to offshore sedimentary systems. We present models for physiographic shelf connection types related to the tectono-sedimentary regime of the margin. Beyond the shelf, the principal agents for microplastic transport are: (i) gravity-driven transport in sediment-laden flows; (ii) settling, or conveyance through biological processes, of material that was formerly floating on the surface or suspended in the water column; (iii) transport by thermohaline currents, either during settling or by reworking of deposited microplastics. We compare microplastic settling velocities to natural sediments to understand how appropriate existing sediment transport models are for explaining microplastic dispersal. Based on this analysis, and the relatively well-known behavior of deep-marine flow types, we explore the expected distribution of microplastic particles, both in individual sedimentary event deposits and within deep-marine depositional systems. Residence time within certain deposit types and depositional environments is anticipated to be variable, which has implications for the likelihood of ingestion and incorporation into the food chain, further transport, or deeper burial. We conclude that the integration of process-based sedimentological and stratigraphic knowledge with insights from modern sedimentary systems, and biological activity within them, will provide essential constraints on the transfer of microplastics to deep-marine environments, their distribution and ultimate fate, and the implications that these have for benthic ecosystems. The dispersal of anthropogenic across the sedimentary systems that cover Earth’s surface has important societal and economic implications. Sedimentologists have a key, but as-yet underplayed, role in addressing, and mitigating this globally significant issue.
While there is now an established recognition of microplastic pollution in the oceans, and the detrimental effects this may have on marine animals, the ocean depth at which such contamination is ingested by organisms has still not been established. Here, we detect the presence of ingested microplastics in the hindguts of Lysianassoidea amphipod populations, in six deep ocean trenches from around the Pacific Rim (Japan, Izu-Bonin, Mariana, Kermadec, New Hebrides and the Peru-Chile trenches), at depths ranging from 7000 m to 10 890 m. This illustrates that microplastic contaminants occur in the very deepest reaches of the oceans. Over 72% of individuals examined (65 of 90) contained at least one microparticle. The number of microparticles ingested per individual across all trenches ranged from 1 to 8. The mean and standard error of microparticles varied per trench, from 0.9 ± 0.4 (New Hebrides Trench) to 3.3 ± 0.7 (Mariana Trench). A subsample of microfibres and fragments analysed using FTIR were found to be a collection of plastic and synthetic materials (Nylon, polyethylene, polyamide, polyvinyl alcohol, polyvinylchloride, often with inorganic filler material), semi-synthetic (rayon and lyocell) and natural fibre (ramie). Notwithstanding, this study reports the deepest record of microplastic ingestion, indicating that anthropogenic debris is bioavailable to organisms at some of the deepest locations in the Earth's oceans.
Millions of metric tons of plastics are produced annually and transported from land to the oceans. Finding the fate of the plastic debris will help define the impacts of plastic pollution in the ocean. Here, we report the abundances of microplastic in the deepest part of the world’s ocean. We found that microplastic abundances in hadal bottom waters range from 2.06 to 13.51 pieces per litre, several times higher than those in open ocean subsurface water. Moreover, microplastic abundances in hadal sediments of the Mariana Trench vary from 200 to 2200 pieces per litre, distinctly higher than those in most deep sea sediments. These results suggest that manmade plastics have contaminated the most remote and deepest places on the planet. The hadal zone is likely one of the largest sinks for microplastic debris on Earth, with unknown but potentially damaging impacts on this fragile ecosystem.
Prevalence of microplastics (MPs) throughout the world's oceans has raised growing concerns due to its detrimental effects on the environment and living organisms. Most recent studies of MPs, however, have focused on the estuaries and coastal regions. There is a lack of study of MPs pollution in the open ocean. In the present study, we conducted field observations to investigate the abundance, spatial distribution, and characteristics (composite, size, color, shape and surface morphology) of MPs at the surface of the Northwestern Pacific Ocean. Samples of MPs were collected at 18 field stations in the Northwestern Pacific Ocean using a surface manta trawl with a mesh size of ~330 μm and width of 1 m from August 25 to September 26, 2017. The MPs were characterized using light microscopy, Micro-Raman spectroscopy, and scanning electron microscopy (SEM). Our field survey results indicate the ubiquity of MPs at all stations with an abundance from 6.4 × 102 items km-2 to 4.2 × 104 items km-2 and an average abundance of 1.0 × 104 items km-2. The Micro-Raman spectroscopic analysis of the MPs samples collected during our field survey indicates that the dominant MPs is polyethylene (57.8%), followed by polypropylene (36.0%) and nylon (3.4%). The individual chemical compositions of MPs from the stations within the latitude range 123-146°E are comparable with each other, with PE being the dominating composition. Similar chemical fingerprints were observed at these field stations, suggesting that the MPs originated from similar sources. In contrast, the major MPs at the field stations adjacent to Japan is polypropylene, which may originate from the nearby land along the coast of Japan. Physical oceanography parameters were also collected at these stations. The spatial distribution of MPs is largely attributed to the combined effects of flow pattern, adjacent ocean circulation eddies, the Kuroshio and Kuroshio Extension system.
The discarding of plastic products has led to the ubiquitous occurrence of microplastic particles in the marine environment. The uptake and depuration kinetics of ingested microplastics for many marine species still remain unknown despite its importance for understanding bioaccumulation potential to higher trophic level consumers. In this study, Antarctic krill (Euphausia superba) were exposed to polyethylene microplastics in order to quantify acute toxicity and ingestion kinetics, providing insight into the bioaccumulation potential of microplastics at the first-order consumer level. In the 10 day acute toxicity assay, no mortality or dose dependant weight loss occurred in exposed krill, at any of the exposure concentrations (0, 10, 20, 40, or 80 % plastic diet). Krill exposed to a 20% plastic diet for 24 hours displayed fast uptake (22 ng mg-1 h-1) and depuration (0.22 h-1) rates, but plastic uptake did not reach steady state. Efficient elimination also resulted in no bioaccumulation over an extended 25 day assay, with most individuals completely eliminating their microplastic burden in less than 5 days post exposure. Our results support recent findings of limited acute toxicity of ingested microplastics at this trophic level, and suggest sublethal chronic endpoints should be the focus of further ecotoxicological investigation.
https://pubs.acs.org/doi/full/10.1021/acs.est.7b05759
Although mounting evidence suggests the ubiquity of microplastic in aquatic ecosystems worldwide, our knowledge of its distribution in remote environments such as Polar Regions and the deep sea is scarce. Here, we analyzed nine sediment samples taken at the HAUSGARTEN observatory in the Arctic at 2,340 - 5,570 m depth. Density separation by MicroPlastic Sediment Separator and treatment with Fenton's reagent enabled analysis via Attenuated Total Reflection FTIR and µFTIR spectroscopy. Our analyses indicate the wide spread of high numbers of microplastics (42 - 6,595 microplastics kg-1). The northernmost stations harbored the highest quantities, indicating sea ice as a transport vehicle. A positive correlation between microplastic abundance and chlorophyll a content suggests vertical export via incorporation in sinking (ice-) algal aggregates. Overall, 18 different polymers were detected. Chlorinated polyethylene accounted for the largest proportion (38 %), followed by polyamide (22 %) and polypropylene (16 %). Almost 80 % of the microplastics were ≤ 25 µm. The microplastic quantities are amongst the highest recorded from benthic sediments, which corroborates the deep sea as a major sink for microplastics and the presence of accumulation areas in this remote part of the world, fed by plastics transported to the North via the Thermohaline Circulation.
A numerical model was established to reproduce the oceanic transport processes of microplastics and mesoplastics in the Sea of Japan. A particle tracking model, where surface ocean currents were given by a combination of a reanalysis ocean current product and Stokes drift computed separately by a wave model, simulated particle movement. The model results corresponded with the field survey. Modeled results indicated the micro- and mesoplastics are moved northeastward by the Tsushima Current. Subsequently, Stokes drift selectively moves mesoplastics during winter toward the Japanese coast, resulting in increased contributions of mesoplastics south of 39°N. Additionally, Stokes drift also transports micro- and mesoplastics out to the sea area south of the subpolar front where the northeastward Tsushima Current carries them into the open ocean via the Tsugaru and Soya straits. Average transit time of modeled particles in the Sea of Japan is drastically reduced when including Stokes drift in the model.
The analysis of imaging data derived from micro-Fourier transform infrared (μFTIR) microscopy is a powerful tool allowing the analysis of microplastics enriched on membrane filters. In this study we present an automated approach to reduce the time demand currently needed for data analyses. We developed a novel analysis pipeline, based on the OPUS© Software by Bruker, followed by image analysis with Python and Simple ITK image processing modules. By using this newly developed pipeline it was possible to analyse datasets from focal plane array (FPA) μFTIR mapping of samples containing up to 1.8 million single spectra. All spectra were compared against a database of different synthetic and natural polymers by various routines followed by benchmark tests with focus on accuracy and quality. The spectral correlation was optimized for high quality data generation, which allowed image analysis. Based on these results an image analysis approach was developed, providing information on particle numbers and sizes for each polymer detected. It was possible to collect all data with relative ease even for complex sample matrices. This approach significantly decreases the time demand for the interpretation of complex FTIR-imaging data and significantly increases the data quality.
The increased global production of plastics has been mirrored by greater accumulations of plastic litter in marine environments worldwide. Global plastic litter estimates based on field observations account only for 1% of the total volumes of plastic assumed to enter the marine ecosystem from land, raising again the question ‘Where is all the plastic? ’. Scant information exists on temporal trends on litter transport and litter accumulation on the deep seafloor. Here, we present the results of photographic time-series surveys indicating a strong increase in marine litter over the period of 2002–2014 at two stations of the HAUSGARTEN observatory in the Arctic (2500 m depth).
Plastic accounted for the highest proportion (47%) of litter recorded at HAUSGARTEN for the whole study period. When the most southern station was considered separately, the proportion of plastic items was even higher (65%). Increasing quantities of small plastics raise concerns about fragmentation and future microplastic contamination. Analysis of litter types and sizes indicate temporal and spatial differences in the transport pathways to the deep sea for different categories of litter. Litter densities were positively correlated with the counts of ship entering harbour at Longyearbyen, the number of active fishing vessels and extent of summer sea ice. Sea ice may act as a transport vehicle for entrained litter, being released during periods of melting. The receding sea ice coverage associated with global change has opened hitherto largely inaccessible environments to humans and the impacts of tourism, industrial activities including shipping and fisheries, all of which are potential sources of marine litter.
Fenton’s reagent was used to isolate microplastics from organic-rich wastewater. The catalytic reaction did not affect microplastic chemistry or size, enabling its use as a pre-treatment method for focal plane array-based micro-FT-IR imaging. Compared with previously described microplastic treatment methods, Fenton’s reagent offers a considerable reduction in sample preparation times.
Marine snow is a predominant form of sinking particulate carbon in the marine water column and represents a mechanism for transporting microplastics to the sea floor. We present a new dual density separation method employing sodium iodide extraction followed by methanol precipitation, specifically designed for microplastic isolation and identification in natural marine snow samples. A total of 59 microscopic particles from eight marine snow samples collected at Avery Point, CT were confirmed as plastics and/or substances containing typical plastic manufacturing additives. Extraction efficiency of this method was determined using polyethylene microspheres of varying sizes (63–75 μm, 212–250 μm and 500–600 μm) yielding 90%, 93% and 98% recoveries, respectively. Residual organic matter which can cause interference in downstream Raman spectroscopic analyses was eliminated by employing a 15% hydrogen peroxide (H2O2) digestion step, which caused negligible chemical modifications to the polymer samples. Extensive precautions such as combusted glassware, a microfiltration air hood, and incorporation of process blank samples ensured that airborne microplastic contamination was avoided. A phase contrast microscope equipped with a Raman spectrophotometer system using a 785 nm laser excitation source efficiently identified anthropogenic polymer materials. Unexpectedly, plastic additives such as pigments complicated the identification of polymers but their spectra were successfully interpreted through spectral subtraction and comparison to a database and authentic standards. The protocol described can be applied to detect microplastic in marine snow samples and improve our understanding of the fate of microplastic in the ocean.
Most studies on buoyant microplastics in the marine environment rely on sea surface sampling. Consequently, microplastic amounts can be underestimated, as turbulence leads to vertical mixing. Models that correct for vertical mixing are based on limited data. In this study we report measurements of the depth profile of buoyant microplastics in the North Atlantic subtropical gyre, from 0 to 5 m depth. Microplastics were separated into size classes (0.5–1.5 and 1.5–5.0 mm) and types ('fragments' and 'lines'), and associated with a sea state. Microplastic concentrations decreased exponentially with depth, with both sea state and particle properties affecting the steepness of the decrease. Concentrations approached zero within 5 m depth, indicating that most buoyant microplastics are present on or near the surface. Plastic rise velocities were also measured, and were found to differ significantly for different sizes and shapes. Our results suggest that (1) surface samplers such as manta trawls underestimate total buoyant microplastic amounts by a factor of 1.04–30.0 and (2) estimations of depth-integrated buoyant plastic concentrations should be done across different particle sizes and types. Our findings can assist with improving buoyant ocean plastic vertical mixing models, mass balance exercises, impact assessments and mitigation strategies.
The deep-ocean interior contains the majority of microbes present on Earth. Most deep-sea microbes are concentrated in surface sediments, with abundances up to 4 orders of magnitude higher, per unit of volume, than in highly productive waters of the photic zone. To date, it has been shown that prokaryotic biomass largely dominates over all other biotic components, but the relative importance of Bacteria, Archaea and viruses to the global benthic biomass has not yet been quantified. Here, we report that the microbial abundance in the top 50 cm of deep-sea sediments of the world oceans is on the order of 1.5 ± 0.4 × 1029. This is largely represented by viruses (9.8 ± 2.5 × 1028), followed by Bacteria (3.5 ± 0.9 × 1028 cells) and Archaea (1.4 ± 0.4 × 1028 cells). The overall biomass in the top 50 cm of the deep-sea sediments is 1.7 ± 0.4 Pg C, largely represented by bacterial biomass (ca. 78%), followed by archaeal biomass (ca. 21%) and viruses (<1%). The bathymetric patterns of abundance and biomass of the 3 microbial components show differences: abundance and biomass of Bacteria decrease with increasing water depth, whereas those of Archaea and viruses remain constant. These results support the hypothesis that the role of Archaea and viruses could be more relevant in the deepest part of the ocean floor.
Marine debris, mostly consisting of plastic, is a global problem, negatively impacting wildlife, tourism and shipping. However, despite the durability of plastic, and the exponential increase in its production, monitoring data show limited evidence of concomitant increasing concentrations in marine habitats. There appears to be a considerable proportion of the manufactured plastic that is unaccounted for in surveys tracking the fate of environmental plastics. Even the discovery of widespread accumulation of microscopic fragments (microplastics) in oceanic gyres and shallow water sediments is unable to explain the missing fraction. Here, we show that deep-sea sediments are a likely sink for microplastics. Microplastic, in the form of fibres, was up to four orders of magnitude more abundant (per unit volume) in deep-sea sediments from the Atlantic Ocean, Mediterranean Sea and Indian Ocean than in contaminated sea-surface waters. Our results show evidence for a large and hitherto unknown repository of microplastics. The dominance of microfibres points to a previously underreported and unsampled plastic fraction. Given the vastness of the deep sea and the prevalence of microplastics at all sites we investigated, the deep-sea floor appears to provide an answer to the question-where is all the plastic?
Automation and subsampling have been proposed as solutions to reduce the time required to quantify and characterize microplastics in samples using spectroscopy. However, there are methodological dilemmas associated with automation that are preventing its widespread implementation including ensuring particles stay adhered to the filter during filter mapping and developing an appropriate subsampling strategy to reduce the time needed for analysis. We provide a solution to the particle adherence issue by applying Skin Tac, a non-polymeric permeable adhesive that allows microplastic particles to adhere to the filter without having their Raman signal masked by the adhesive. We also explore different subsampling strategies to help inform how to take a representative subsample. Based on the particle distributions observed on filters, we determined that assuming a homogenous particle distribution is inappropriate and can lead to over- and under-estimations of extrapolated particle counts. Instead, we provide recommendations for future studies that wish to subsample to increase the throughput of samples for spectroscopic analysis.
Fishery activities are an important source of microplastic pollution in coastal areas but have received little attention. The Beibu Gulf, a traditional fishing ground of China and the China-Indo Peninsula, was selected in this study, and the focus was on the impacts of fishery activities on the horizontal distribution of microplastics in sediment. The results showed that the dominant contaminants (polypropylene fibers and polyethylene fibers) might originate from the abrasion of fishing gear and contributed to 61.6% of the total abundance of microplastics in surface sediment. The abundance of polypropylene fibers and polyethylene fibers exhibited a strong correlation (R2 = 0.8586, p = 0.015) with values of fishery yields of different districts, which highlighted the effects of different fishery activities on microplastic contamination in marine sediment. Microplastics could be "hidden" in deep sediment to a depth of 60 cm. The estimated storage of microplastics in deep sediment (185 tons) was 5 times that in surface sediment. The assessment of microplastic storage worldwide might be underestimated because most previous studies only examined surface sediment. The abundance distribution and size distribution of microplastics in the sediment core suggested long-term burial of microplastics in deep sediment. Bioturbation might be responsible for the vertical transport of microplastics, leading to "fresh microplastics" preservation in "old sediment".
Microplastics are ubiquitous in marine environments. Sediments and marine organisms are recognized as the carriers and final destinations of microplastics. However, research on the concentration and abundance of microplastics in deep-sea sediments and organisms is limited. In this study, samples of sediments and organisms were collected from deep-sea locations of the western Pacific Ocean, with the depth ranging from 4601 m to 5732 m. Microplastics were extracted from the samples and analyzed by micro-Fourier-transform infrared spectroscopy. The average abundance of microplastics in the sediments was 240 items per kg dry weight of sediment. The microplastics were predominantly fibrous in shape (52.5%), blue in color (45.0%), and less than 1 mm in size (90.0%). The most commonly detected polymers were poly(propylene-ethylene) copolymer (40.0%) and polyethylene terephthalate (27.5%). The concentrations of polychlorinated biphenyls (PCBs), which are representatives of persistent organic pollutants, in the pore water of sediment samples were also investigated. A significant correlation between the distribution of microplastics and the PCB concentrations in sediments was found (P = 0.016). Microplastics were also detected in deep-sea organisms (i.e., Crinoidea, Pheronematidae, Ophiuroidea, and Gammaridea) in the sampling region, with an abundance of 0-3 items per individual biological sample. This assessment of microplastics in deep-sea sediments and benthic organisms of the western Pacific Ocean confirms that microplastic pollution exists in the deep-sea ecosystems of this region.
Plastic debris and marine microplastics are being discharged into the ocean at an alarming scale and have been observed throughout the marine environment. Here we report microplastic in sediments of the Challenger Deep, the deepest known region on the planet, abyssal plains and hadal trenches located in the Pacific Ocean (4900 m-10,890 m). Microplastic abundance reached 71.1 items per kg dry weight sediment. That high concentrations are found at such remote depths, knowing the very slow sinking speed of microplastics, suggests that supporting mechanisms must be at-play. We discuss cascading processes that transport microplastics on their journey from land and oceanic gyres through intermediate waters to the deepest corners of the ocean. We propose that hadal trenches will be the ultimate sink for a significant proportion of the microplastics disposed in the ocean. The build-up of microplastics in hadal trenches could have large consequences for fragile deep-sea ecosystems.