Deep Sea Microplastic Pollution Extends Out to Sediments in the Northeast Atlantic Ocean Margins

Immune response to polystyrene microplastics: Regulation of inflammatory response via the ROS-driven NF-κB pathway in zebrafish (Danio rerio)

There is increasing apprehension regarding the rising prevalence of microplastics (MPs) in aquatic ecosystems. Although MPs cause toxicological effect on fish via diverse pathways, the precise immunotoxicological mechanism is yet to be fully understood. Utilizing zebrafish in early developmental stages and zebrafish embryonic fibroblast (ZF4) as models, this study delved into the immune response elicited by polystyrene MPs (PS-MPs). It was observed that larvae predominantly accumulate 3 μm PS-MPs in their intestines through ingestion, leading to notable changes in locomotor behavior and histopathological alterations. Further investigation revealed that short-term exposure to PS-MPs triggers oxidative stress (OS) and inflammation in zebrafish. This is evidenced by the upregulation of OS and inflammation-related genes, increased levels of reactive oxygen species (ROS), malonaldehyde (MDA), and inflammatory cytokines, altered activities of antioxidant enzymes, along with induced recruitment of leukocyte in larvae. Cellular assays confirmed that PS-MPs elevate intracellular ROS in ZF4 cells and enhance the nuclear translocation of NF-κB P65. Notably, the activation of NF-κB and the upsurge in inflammatory cytokines can be mitigated by inhibiting ROS. This research highlights the significance of the ROS-triggered NF-κB signaling cascade in PS-MPs-mediated inflammation within zebrafish, illuminating the possible processes that underlie the innate immune system of fish toxicity caused by MPs.

Methane seepage leads to a specific microplastic aging process in the simulated cold seep environment

Marine microplastics pose a significant threat to ecosystems, and deep-sea regions serve as critical sinks for these pollutants. Among these regions, cold seeps harbor relatively high concentrations of microplastics. However, research on the aging of microplastics under low-temperature, dark, methane-abundant, and high-pressure conditions remains limited. Seawater and sediment were collected from various Haima cold seepage sites to simulate seepage environments in 200-mL high-pressure reactors. Four types of microplastics at high concentrations (approximately 10 %) were cultured and monitored over two months to explore how they aged. The key findings are as follows: (1) Compared to areas of weak seepage, methane seepage accelerated microplastic aging, as evidenced by increased surface roughness, enhanced C-O and (CO)-O bond formation, increased microbial colonization, and reduced contact angles. (2) Microplastic aging is more pronounced in sediments than in seawater, with biodegradable polylactic acid (PLA) exhibiting the most significant aging characteristics and carbon contribution. (3) Aged microplastics induce greater disturbances in inorganic nutrient levels than in organic matter, impacting nitrogen cycle processes involving nitrate, nitrite, and ammonium. This study results reveal the fundamental aging characteristics of microplastics in extremely deep seas and highlight their potential ecological effects.

Record of microplastic deposition revealed by ornithogenic soil and sediment profiles from Ross Island, Antarctica

Microplastics (MPs) are a global concern as an emerging pollutant, and the investigation on MPs in Antarctic aids in informing their global pollution assessments. Therefore, there are urgent scientific concerns regarding the environmental behavior, origins, influencing factors, and potential hazards of MPs in Antarctica. This study presents the characteristics of MPs from one ornithogenic sediment profile (coded CC) and two ornithogenic soil profiles (coded MR1 and MR2) from ice-free areas on Ross Island, Antarctica. We explored the potential sources of MPs and the main influencing factors for deposition based on their distribution with depth in the profiles. Through laser-infrared imaging spectroscopy (LDIR), a total of 30 polymer types were identified in all samples, with polyethylene terephthalate (PET) and polyvinyl chloride (PVC) as the dominant types, accounting for more than 70% of the total. The abundance of MPs in the CC sediment profile ranged from 2.83 to 394.18 items/g, while in MR1 and MR2 soil profiles, the abundance ranged from 2.25 to 1690.11 and 8.24 to 168.27 items/g, respectively. The size of MPs was mainly concentrated in the range of 20-50 μm, and possible downward movement of certain polymer types was revealed. From the perspective of temporal variation, we suggest that MPs were heavily influenced by local human activities including scientific research, fishing, and tourism, balanced by protective regulations, while no solid evidence was obtained to support strong influence from biological transport through penguins. This research enhances our understanding on the environmental behavior of MPs in the terrestrial systems of remote polar regions.

Microplastics and cellulosic microparticles in North Atlantic deep waters and in the cold-water coral Lophelia pertusa

This study explores microplastic and cellulosic microparticle occurrences in the NE Atlantic, focusing on the Porcupine Bank Canyon and Porcupine Seabight. Water samples from depths ranging between 605 and 2126 m and Lophelia pertusa coral samples from 950 m depth were analysed. Microparticles were detected in deep-water habitats, with concentrations varying from 2.33 to 9.67 particles L-1 in the Porcupine Bank Canyon, notably lower at greater depths. This challenges the assumption of deeper habitats solely acting as microplastic sinks. We also found evidence of microparticle adsorption and ingestion by L. pertusa. The presence of microparticles in cold-water corals underscores their vulnerability to pollutants. Furthermore, the dominance of rayon microparticles in both water and coral samples raises questions about marine pollution sources, potentially linked to terrestrial origins. This research emphasises the critical need for comprehensive exploration and conservation efforts in deep-sea environments, especially to protect vital ecosystems like L. pertusa reefs.

Microplastic Contamination of a Benthic Ecosystem in a Hydrothermal Vent

Plastic contamination is a global pervasive issue, extending from coastal areas and open oceans to polar regions and even the deep sea. Microplastic (MP) contamination in hydrothermal vents, which are known for their high biodiversity even under extreme conditions, has remained largely unexplored. Here, we present, for the first time, MP pollution in a deep-sea hydrothermal vent at one of the biodiversity hotspots─the Central Indian Ridge. Not only the environment (seawater: 2.08 ± 1.04 MPs/L, surface sediments: 0.57 ± 0.19 MP/g) but also all six major benthic species investigated were polluted by MPs. MPs mainly consisted of polypropylene, polyethylene terephthalate, and polystyrene fragments ≤100 μm and were characterized as being either transparent or white in color. Remarkably, bioaccumulation and even biomagnification of microplastics were observed in the top predators of the ecosystem, such as squat lobsters (14.25 ± 4.65 MPs/individual) and vent crabs (14.00 ± 2.16 MPs/individual), since they contained more MPs than animals at lower trophic levels (e.g., mussels and snails, 1.75-6.00 average MPs/individuals). These findings reveal MP contamination of an ecosystem in a hydrothermal vent, thereby suggesting that their accumulation and magnification can occur in top-level animals, even within remote and extreme environments.

A Novel High-Throughput Detection Method for Plastic Debris in Organic-Rich Matrices Based on Image Fusion

Plastic pollution pervades natural environments and wildlife. Consequently, high-throughput detection methods for plastic debris are urgently needed. A novel method was developed to detect plastic debris larger than 0.5 mm, which integrated an extraction method with low organic loss and plastic damage alongside a classification method for fused images. This extraction method broadened the size range of the remaining plastic debris, while the fusion solved the low spatial resolution of hyperspectral images and the absence of spectral information in red-green-blue (RGB) images. This method was validated for plastic debris in digestate, compost, and sludge, with extraction demonstrating 100% recovery rates for all samples. After fusion, the spatial resolution of hyperspectral images was improved about five times. Classification recall for the fused hyperspectral images achieved 97 ± 8%, surpassing 83 ± 29% of the raw images. Application of this method to solid digestate detected 1030 ± 212 items/kg of plastic debris, comparable with the conventional Fourier transform infrared spectroscopic result of 1100 ± 436 items/kg. This developed method can investigate plastic debris in complex matrices, simultaneously addressing a wide range of sizes and types. This capability helps acquire reliable data to predict secondary microplastic generation and conduct a risk assessment.

Spatial monitoring of microplastics in environmental matrices from Galway Bay, Ireland

Microplastic concentrations have been reported in a variety of environmental matrices and organisms across the world. Assessments of environmental concentrations are essential to understand trends and ensure decision-making processes that reduce environmental pressure. In this study, a combined sampling approach to surface waters, benthic sediments and biota in Galway Bay, Ireland, was carried out. Average concentrations of microplastics in surface waters were 1.42 ± 0.33 MPs m-3, in biota were 4.46 ± 0.36 MPs ind-1 and in benthic sediments were 5.60 ± 1.54 MPs kg-1. The diversity of polymers, microplastic types and colours were more abundant in surface waters and biota, when compared to benthic sediments. Integrated assessments of microplastics that follow existing monitoring programmes are essential to understand environmental trends. This work contributes to provide valuable information to descriptor 10 of the Marine Strategy Framework Directive in Ireland.

Sunscreens and micro(nano)plastics: Are we aware of these threats to the Egyptian coral reefs?

During a snorkeling trip to Marsa Alam and Hamata (southern Red Sea Riviera, Egypt) I explored the coral reefs and the diverse marine habitats of fish and invertebrate species. The area invites recreational diving and snorkeling, but the beaches are littered with all sorts of solid waste (mainly fragmented plastics). Also, there are no local restrictions on sunscreen use. The development of tourism to the area raises questions about the environmental impact and how its further growth will have on coral reefs. Every year, 1.2 million tourists visit the Red Sea coast (about 3287 tourists per day) and release about 1.7 tons/month of sunscreen into the Red Sea. As an ecologist and editorial board member of Science of the Total Environment, I ask myself how we as scientists can increase public awareness and call for prompt actions to protect the coral reefs. The discussion underlines two major threats to the Egyptian coral reefs: sunscreen use and micro(nano)plastics waste. The discussion closes with possible solutions, future perspectives, and recommendations to protect the coral reefs ecosystem of the Egyptian Red Sea.

Mechanistic Understanding toward the Maternal Transfer of Nanoplastics in Daphnia magna

Nanoplastics induce transgenerational toxicity to aquatic organisms, but the specific pathways for the maternal transfer of nanoplastics remain unclear. Herein, laser scanning confocal microscopy (LSCM) observations identified the specific pathways on the maternal transfer of polystyrene (PS) nanoplastics (25 nm) in Daphnia magna. In vivo and in vitro experiments showed that PS nanoplastics could enter the brood chamber through its opening and then be internalized to eggs and embryos using LSCM imaging (pathway I). In addition, PS nanoplastics were observed in the oocytes of the ovary, demonstrating gut-ovary-oocyte transfer (pathway II). Furthermore, label-free hyperspectral imaging was used to detect the distribution of nanoplastics in the embryos and ovary of Daphnia, again confirming the maternal transfer of nanoplastics through the two pathways mentioned above. The contribution from pathway I (88%) was much higher than pathway II (12%) based on nanoflow cytometry quantification. In addition, maternal transfer in Daphnia depended on the particle size of PS nanoplastics, as demonstrated by using LSCM and hyperspectral imaging. Unlike 25 nm nanoplastics, 50 nm PS nanoplastics could enter the brood chamber and the eggs/embryos (pathway I), but were not detected in the ovary (pathway II); 100 nm PS nanoplastics were difficult to be internalized by eggs/embryos and could not enter the ovary either. These findings provide insight into the maternal transfer mechanisms of nanoplastics in Daphnia, and are critical for better understanding the transgenerational toxicity of aquatic organisms.