The physical oceanography of the transport of floating marine debris

Marine plastic debris floating on the ocean surface is a major environmental problem. However, its distribution in the ocean is poorly mapped, and most of the plastic waste estimated to have entered the ocean from land is unaccounted for. Better understanding of how plastic debris is transported from coastal and marine sources is crucial to quantify and close the global inventory of marine plastics, which in turn represents critical information for mitigation or policy strategies. At the same time, plastic is a unique tracer that provides an opportunity to learn more about the physics and dynamics of our ocean across multiple scales, from the Ekman convergence in basin-scale gyres to individual waves in the surfzone. In this review, we comprehensively discuss what is known about the different processes that govern the transport of floating marine plastic debris in both the open ocean and the coastal zones, based on the published literature and referring to insights from neighbouring fields such as oil spill dispersion, marine safety recovery, plankton connectivity, and others. We discuss how measurements of marine plastics (both in situ and in the laboratory), remote sensing, and numerical simulations can elucidate these processes and their interactions across spatio-temporal scales

Secondary Microplastics Generation in the Sea Swash Zone With Coarse Bottom Sediments: Laboratory Experiments

Marine beaches worldwide are nowadays exposed to significant contamination by plastics. On the Baltic beaches, polyethylene, polypropylene, and polystyrene are most abundant. We investigate the generation of microplastics particles (MPs, characteristic size from 0.5 to 5 mm) from larger plastic items in the sea swash zone using a laboratory rotating mixer filled with water and natural coarse beach sediment (marine pebbles). Inclination of the axis of rotation and the volume of the material were adjusted in such a way that mixing resembled a breaking wave in the swash zone. Plastic samples used were of the types most commonly found on the sea beaches. Experimental 2 × 2 cm-large plastic items made of low-density polyethylene (LDPE) were manufactured from common new garbage bags (thickness 5 μm); those made of polypropylene (PP) and polystyrene (PS) were produced from single-use tableware; samples of foamed plastics were presented by cubes (with 2-cm sides) cut out of standard building insulator sheets (foamed PS). Four sets of 24-h-long experiments were conducted (for each type of plastic separately), with step-wise (every 3 h) examination of the generated MPs mass, number of particles, and their qualitative characteristics such as shape, quality of the surface, general behavior while mixing, etc. Statistically significant dependencies are obtained for the increase in mass and in number of MPs with time for all four used kinds of plastics. Brittle solid PS is shown to be the most productive in terms of both mass and number of MPs generated. Anisotropic springing PP is the most resistant. Tensile tearing of LDPE and fragmentation of foamed PS to compounding bubbles/spherules show the variety of mechanisms involved in fragmentation of plastics in the swash zone. Increase in MPs mass and the number of MPs particles with time, as well the link between them, are important for field monitoring and numerical modeling. Potentially shape-selective operation of sieves during sampling and sorting of MPs particles of various shapes is discussed

Electrotechnological Heat Treatment of Milk: Energy and Exergy Efficiency

The dairy industry needs new and more energy-efficient technological procedure for milk pasteurization. This article introduces a comparative efficiency assessment of various milk pasteurization technologies and electrotechnological means. The study featured milk, which was heated from 20 to 75°C with a capacity of 1000 kg/h at an estimated power of 58.95 kW. The treatment involved a steam-to-milk pasteurizer with electric indirect or direct heating, an induction pasteurizer, and a thermosiphon pasteurizer with direct or indirect electric heating. The study relied on the methods of energy and exergy analyses. The system of steam-to-milk pasteurizer with electric indirect (elemental, induction) or direct (electrode) heating demonstrated the following indicators: exergy loss – 1.29 kW, power consumption – 71.29 kW, exergy efficiency – 0.99, energy efficiency – 0.827. The thermosiphon pasteurizer with direct or indirect electric heating demonstrated the following properties: exergy loss – 1.29 kW, power consumption – 60.92 kW, exergy efficiency – 0.99, energy efficiency – 0.9676. The induction pasteurizer had the least competitive parameters: exergy loss – 10.8 kW, power consumption – 70.43 kW, exergy efficiency – 0.867, energy efficiency – 0.837. The thermosiphon pasteurizer with direct or indirect electric heating was able to increase the energy efficiency of milk pasteurization, while the induction pasteurizer proved to be a promising R&D direction

Editorial: Challenges in characterizing nano- to macro-plastics and adhered substances in the aquatic environment

Globally, plastic contamination is one of the serious planetary threats, affecting almost all environmental matrices such as air, water, soil, sediment, and biota (including humans). It is estimated that ∼19 to 23 million metric tonnes of plastic waste were generated and entered the environment in 2016, worldwide (Borrellee et al., 2020). Moreover, as the trend goes, the predicted growth in plastic waste may exceed efforts to mitigate plastic pollution around the world. Even with immediate and concerted action, it is estimated that 710 million tons of plastic waste will enter the aquatic and terrestrial ecosystems by 2040 (Lau et al., 2020). Therefore, many countries around the world are struggling to manage the current volume of plastic waste and plastic contamination in the environment. Based on the size, plastic waste is categorized into nanoplastics (1 nm to 5 mm to <10 mm), and macroplastics (≥10 mm). Plastic itself can be a pollutant, but it can also act as a vector to transport toxic chemicals (e.g., persistent organic pollutants, trace metals, pesticides, and antibiotics) and harmful organisms (e.g., pathogens and invasive species) to pristine ecosystems. Therefore, these pollutants are of great public concern due to their ubiquitous nature and the potential hazards posed for humans and ecosystems.We wish to thank the Frontiers in Environmental Science Editorial Office, especially Sara Ceci and Petia Apostolova for their valuable guidance during the entire publication period. The work was also supported by Qatar Energy funded project (QUEX-ESC-QP-TM-18/19) and “UNESCO Chair in Marine Sciences” related to the theme “Marine pollution and Management”

Vertical and seasonal variations in biofilm formation on plastic substrates in coastal waters of the Black Sea

Plastic contamination of the marine environment is an increasing concern worldwide. Therefore, it is important to understand the kinetics of biofilms on plastics to study their behavior, fate, and transport pathways in the ocean. In this study, the vertical and seasonal variations in biofouling formation on transparent polyethylene terephthalate (PET) plastic fragments in the Southwest Crimea coastal waters of the Black Sea were investigated. Biofilms were identified in the transient light as ‘dark spots’ on the plastic surface, for which the numbers, size, and area were measured using specialized software. The rate of biofouling in the surface water layer was lower than those found in the middle and near-bottom water column, which could be due to a damaging effect of turbulent mixing on the biofilm. The highest rates of biofouling and diverse community were observed during the summer. The epibiotic assembly was represented by diatoms (11 taxa), dinoflagellates (3 taxa), green algae, filamentous cyanobacteria, small flagellates, and ciliates. Significant differences between the biofouling rates observed in different seasons made it difficult to estimate the period of time the plastic substrate has been in the marine environment. It was proposed to use the green alga Phycopeltis arundinacea (Montgn) De Tender et al., 2015 as a bioindicator to study the age of the biofouling community. Discoid thalli were identified at all stages of colonization of the plastic fragments in different seasons. Results obtained in this study demonstrate that biofouling organisms may be good model organisms in revealing age of biofilm formation and longevity of plastic debris in the ocean. Consequently, it is proposed that such biofouling organisms could be used as target species to monitor the biodegradation of plastic debris.This work is a part of the joint Indo-Russian research project, entitled ‘Identification and modelling of microplastics transport in the coastal areas under the influence of dominant wind patterns’ (Russian authors were supported by RFBR grant #18-55-45024), and the Russian state assignment No. 121040600178–6. For additional analysis and manuscript preparation AB was supported by the state assignment of MHI on theme No. 555-2021-0005

Investigations of plastic contamination of seawater, marine and coastal sediments in the Russian seas: a review

Twelve seas with an integral coastline length of about 38,000 km wash upon the Russian coasts. They belong to the basins of the Atlantic, the Arctic, and the Pacific Oceans and stretch over temperate, subpolar, and polar climate zones. This review of 32 studies published between 2015 and August 2020 analyses the available peer-reviewed scientific publications related to the topic of plastic contamination. At present, plastic contamination of the marine environments is confirmed by field investigations in 7 out of 12 Russian seas. Pollution levels vary widely: from 0.6 to 336,000 items/m for microplastics in water and from 1.3 to 10,179 items/kg (DW)—in sediments, while median macroplastics abundance is around 1.0 item/m at the coast. One monitoring survey of the Barents Sea reported mean macroplastics concentration in the upper 60 m as 0.011 mg/m and 2.9 kg/km at the sea floor. The identification of the polymer types with spectroscopy techniques is performed only in 9 studies (28%); most researchers use visual identification which makes the results difficult to compare. Most projects aimed at the plastic contamination research use their own collection and extraction methods that poorly agree with other studies. Since the pollution levels in most of the areas are relatively low, sampling is inhomogeneous in space and time. The most extensively studied areas are the beaches of the Baltic Sea, while the least examined is the Arctic region. Our study highlights the need for a discussion on harmonizing sampling methodology and identification techniques among different studies. 3 2 3

The differences in immunoadjuvant mechanisms of TLR3 and TLR4 agonists on the level of antigen-presenting cells during immunization with recombinant adenovirus vector

Abstract Background Agonists of TLR3 and TLR4 are effective immunoadjuvants for different types of vaccines. The mechanisms of their immunostimulatory action differ significantly; these differences are particularly critical for immunization with non-replicating adenovirus vectors (rAds) based vaccines. Unlike traditional vaccines, rAd based vaccines are not designed to capture vaccine antigens from the external environment by antigen presenting cells (APCs), but rather they are targeted to the de novo synthesis of vaccine antigens in APCs transfected with rAd. To date, there is no clear understanding about approaches to improve the efficacy of rAd vaccinations with immunoadjuvants. In this study, we investigated the immunoadjuvant effect of TLR3 and TLR4 agonists on the level of activation of APCs during vaccination with rAds. Results We demonstrated that TLR3 and TLR4 agonists confer different effects on the molecular processes in APCs that determine the efficacy of antigen delivery and activation of antigen-specific CD4+ and CD8+ T cells. APCs activated with agonists of TLR4 were characterized by up-regulated production of target antigen mRNA and protein encoded in rAd, as well as enhanced expression of the co-activation receptors CD80, CD86 and CD40, and pro-inflammatory cytokines TNF-α, IL6 and IL12. These effects of TLR4 agonists have provided a significant increase in the number of antigen-specific CD4+ and CD8+ T cells. TLR3 agonist, on the contrary, inhibited transcription and synthesis of rAd-encoded antigens, but improved expression of CD40 and IFN-β in APCs. The cumulative effect of TLR3 agonist have resulted in only a slight improvement in the activation of antigen-specific T cells. Also, we demonstrated that IFN-β and TNF-α, secreted by APCs in response to TLR3 and TLR4 agonists, respectively, have an opposite effect on the transcription of the targeted gene encoded in rAd. Specifically, IFN-β inhibited, and TNF-α stimulated the expression of target vaccine antigens in APCs. Conclusions Our data demonstrate that agonists of TLR4 but not TLR3 merit further study as adjuvants for development of vaccines based on recombinant adenoviral vectors

Contributions of Fourier transform infrared spectroscopy in microplastic pollution research: A review

© 2020 Taylor & Francis Group, LLC. Fourier transform infrared (FTIR) spectroscopy has been extensively used in microplastic (MP) pollution research since 2004. The aim of this review is to discuss and highlight the recent advances in FTIR (spectroscopy and chemical imaging) techniques that are used to characterize various polymer types of MPs and to trace their fate and transport in different environmental matrices. More than 400 research papers dealing with FTIR techniques in MP pollution research, which are published between January 2010 and December 2019, have been identified from the Scopus and Web of Science databases. The MPs present in sediment, water (marine and freshwater), biota, air/dust, waste water treatment plants and salt are further classified according to (1) characterization and identification, (2) weathering and aging, (3) ecotoxicology, and (4) analytical methods. The results revealed that the ATR-FTIR technique is mostly used to identify and characterize the MPs found in water and sediment. The µFTIR (FTIR imaging) is extensively used to study the ingestion of MPs in biota (both marine and freshwater). In this article, we have summarized the current knowledge of application of FTIR spectroscopy to MP research and provided insights to future challenges for understanding the risk of MPs

Additional file 1: of The differences in immunoadjuvant mechanisms of TLR3 and TLR4 agonists on the level of antigen-presenting cells during immunization with recombinant adenovirus vector

Figure S1. Effect of TLR agonists on the expression of rAd in DCs. DCs were transduced with rAdTet-off H1 (100 PFU per cell) in the presence of 10 μg/ml agonists of TLR3 (Poly I:C) or TLR4 (LPS, IMM); 24 h after transfection cells were stained with primary (H1-specific) and secondary fluorochrome labeled antibodies. The mean fluorescence (MFI) of H1-positive DCs in the test samples was detected by flow cytometry. Shown are M ± SD, statistically significant (p < 0.05) differences are indicated by asterisks. Figure S2. Effect of TLR3- and TLR4-activated APCs on the reactivation of CD4+ and CD8+ T-cells. Balb/c mice were immunized (i.m.) with 108 PFU rAdTet-off H1. Forty days after immunization, the pool of CD8+ (a, c) and CD4+ (b, d) T cells from the spleen of euthanized immune mice was re-activated in vitro. Sorted CD8+ and CD4+ T cells were co-cultured with bone marrow derived DCs (c, d) or macrophages (MF) (a, b) preloaded with 20 PFU/cell rAdTet-off H1 in the presence of 0–10 μg/ml agonists of TLR3 (Poly I:C) or TLR4 (LPS, IMM). The number of reactivated IFNγ-producing T-cells were detected by ELISPOT and calculated for 1 million spleen cells. Shown are M ± SD, statistically significant differences (p < 0.05) are indicated by asterisks. (PDF 123 kb