Coastal seas and oceans receive engineered nanoparticles that are released from nano-enabled consumer and industrial products and incidental nanoparticles that are formed as byproducts of combustion and friction. The marine environment is often perceived as a rapid sink for particles, because of the high salinity promoting the attachment between particles producing heavy agglomerates that sediment on the seafloor. In this work the effect of seasonal production of extracellular polymeric substances (EPS) on particle stability is tested using seawater collected from the Gullmarn fjord in the winter, spring, and summer. A novel approach is used that is based on light scattering of the bulk particle population for tracking agglomerates and of single particles for tracking particles smaller than approximately 300 nm. Results show that organic particles formed from EPS during algal blooms are capable of stabilizing nanoparticles in marine waters for at least 48 h. In contrast, particles agglomerate rapidly in the same seawater that has previously been filtered through 0.02 μm pore size membranes. Furthermore, particles with fibrillar shape have been detected using atomic force microscopy, supporting the argument that organic particles from EPS are responsible for the stabilization effect. These results suggest that seasonal biological activity can act as an intermittent stabilization factor for nanoparticles in marine waters.
Pollution and Marine Debris
Microplastics, particularly microfibers, are ubiquitous, found in aquatic (freshwater and marine) and terrestrial environments and within the food web worldwide. It is well-established that microplastics in the form of textile fibers enter the environment via washing machines and wastewater treatment effluent. Less is known about the release of microfibers from electric clothes dryers. In this study we measure microfiber emissions from home installed dryers at two different sites. At each site the distribution of fibers landing on the snow’s surface outside dryer vents and the weight of lint in dryer exhaust exiting dryer vents were measured. Fibers from the pink polyester fleece blankets used in this study were found in plots throughout a 30ft (9.14m) radius from the dryer vents, with an average number across all plots of 404 ± 192 (SD) (Site 1) and 1,169 ± 606 (SD) (Site 2). The majority of the fibers collected were located within 5 ft (1.52m) of the vents. Averages of 35 ± 16(SD)mg (Site 1) and 70 ± 77 (SD)mg (Site 2) of lint from three consecutive dry cycles were collected from dryer vent exhaust. This study establishes that electric clothes dryers emit masses of microfiber directly into the environment. Microfiber emissions vary based on dryer type, age, vent installation and lint trap characteristics. Therefore, dryers should be included in discussions when considering strategies, policies and innovations to prevent and mitigate microfiber pollution.
Marine litter is a significant and growing pollutant in the oceans. In recent years, the number of studies and initiatives trying to assess and tackle the global threat of marine litter has grown exponentially. Most of these studies, when considering macro-litter, focus on floating or stranded litter, whereas there is less information available about marine litter on the seabed. The aim of this article is to give an overview of the current state-of-the-art methods to address the issue of seafloor macro-litter pollution. The overview includes the following topics: the monitoring of macro-litter on the seafloor, the identification of possible litter accumulation hot spots on the seafloor through numerical models, and seafloor litter management approaches (from removal protocols to recycling processes). The article briefly analyzes the different approaches to involve stakeholders, since the marine litter topic is strongly related to the societal engagement. Finally, attempting to answer to all the critical aspects highlighted in the overview, the article highlights the need of innovative multi-level solutions to induce a change toward sustainable practices, transforming a problem into a real circular economy opportunity.
Biogenic reefs are known worldwide to play a key role in benthic ecosystems, enhancing biodiversity and ecosystem functioning at every level, from shallow to deeper waters. Unfortunately, several stressors threaten these vulnerable systems. The widespread presence of marine litter represents one of these. The harmful effects of marine litter on several organisms are known so far. However, only in the last decade, there was increasingly scientific and public attention on the impacts on reef organisms and habitats caused by litter accumulating on the seafloor. This review aims to synthesize literature and discuss the state of current knowledge on the interactions between marine litter and reef organisms in a strongly polluted basin, the Mediterranean Sea. The multiple impacts (e.g., entanglement, ghost-fishing, coverage, etc.) of litter on reef systems, the list of species impacted, and the main litter categories were identified, and a map of the knowledge available so far on this topic was provided. Seventy-eight taxa resulted impacted by marine litter on Mediterranean reefs, and the majority belonged to the phylum Cnidaria (41%), including endangered species like the red coral (Corallium rubrum) and the madrepora coral (Madrepora oculata). Entanglement, caused mainly by abandoned, lost, or otherwise discarded fishing gear (ALDFG), was the most frequent impact, playing a detrimental effect mainly on coralligenous arborescent species and cold-water corals (CWCs). The information was spatially heterogeneous, with some areas almost uncovered by scientific studies (e.g., the Aegean-Levantine Sea and the Southern Mediterranean Sea). Although many legal and policy frameworks have been established to tackle this issue [e.g., marine strategy framework directive (MSFD) and the Barcelona Convention], several gaps still exist concerning the assessment of the impact of marine litter on marine organisms, and in particular on reefs. There is a need for harmonized and standardized monitoring protocols for the collection of quantitative data to assess the impact of litter on reefs and animal forests. At the same time, urgent management measures limiting, for instance, the impact of ALDFG and other marine litter are needed to preserve these valuable and vulnerable marine ecosystems.
Interest in understanding the extent of plastic and specifically microplastic pollution has increased on a global scale. However, we still know relatively little about how much plastic pollution has found its way into the deeper areas of the world’s oceans. The extent of microplastic pollution in deep-sea sediments remains poorly quantified, but this knowledge is imperative for predicting the distribution and potential impacts of global plastic pollution. To address this knowledge gap, we quantified microplastics in deep-sea sediments from the Great Australian Bight using an adapted density separation and dye fluorescence technique. We analyzed sediment cores from six locations (1–6 cores each, n = 16 total samples) ranging in depth from 1,655 to 3,062 m and offshore distances ranging from 288 to 356 km from the Australian coastline. Microplastic counts ranged from 0 to 13.6 fragments per g dry sediment (mean 1.26 ± 0.68; n = 51). We found substantially higher microplastic counts than recorded in other analyses of deep-sea sediments. Overall, the number of microplastic fragments in the sediment increased as surface plastic counts increased, and as the seafloor slope angle increased. However, microplastic counts were highly variable, with heterogeneity between sediment cores from the same location greater than the variation across sampling sites. Based on our empirical data, we conservatively estimate 14 million tonnes of microplastic reside on the ocean floor.
The increasing amount of marine plastic waste poses challenges including, not only the collection, but also the subsequent recyclability of the plastic. An artificial accelerated weathering procedure was developed, which modelled the marine environment and investigated the recyclability of weathered and non-weathered PET. Marine conditions were simulated for poly(ethylene terephthalate) (PET) bottle material and high-density polyethylene (HDPE) cap material. It consisted of 2520 h cyclical weathering, alternating the sample between a salt spray and a Xenon-chamber—this corresponds to roughly 3–4 years on the surface of an ocean.
It was proved that the molecular weight of PET is a function of weathering time and can be described mathematically. Microscopic examination of the surface of the PET bottles and HDPE caps proved that these surfaces were damaged. After weathering, manufacturing tests were performed on the PET material by extrusion, injection moulding, 3D printing and thermoforming. Quantitative comparison between products manufactured by the same technology was performed in order to compare the qualities of products made from original PET, non-weathered PET waste, which was the example of classical recycling, and weathered PET. In the case of products made from weathered PET, certain mechanical and optical properties (e.g. impact strength and transparency) were significantly impaired compared to the original PET and the recycled, non-weathered PET. Certain other properties (e.g. strength and rigidity) did not change significantly. It was proved that the samples from weathered plastic material can be successfully recycled mechanically and used to manufacture plastic products.
As plastic waste accumulates in the ocean at alarming rates, the need for efficient and sustainable remediation solutions is urgent. One solution is the development and mobilization of technologies that either 1) prevent plastics from entering waterways or 2) collect marine and riverine plastic pollution. To date, however, few reports have focused on these technologies, and information on various technological developments is scattered. This leaves policymakers, innovators, and researchers without a central, comprehensive, and reliable source of information on the status of available technology to target this global problem. The goal of this study was to address this gap by creating a comprehensive inventory of technologies currently used or in development to prevent the leakage of plastic pollution or collect existing plastic pollution. Our Plastic Pollution Prevention and Collection Technology Inventory (https://nicholasinstitute.duke.edu/plastics-technology-inventory) can be used as a roadmap for researchers and governments to 1) facilitate comparisons between the scope of solutions and the breadth and severity of the plastic pollution problem and 2) assist in identifying strengths and weaknesses of current technological approaches. We created this inventory from a systematic search and review of resources that identified technologies. Technologies were organized by the type of technology and target plastics (i.e., macroplastics, microplastic, or both). We identified 52 technologies that fall into the two categories of prevention or collection of plastic pollution. Of these, 59% focus specifically on collecting macroplastic waste already in waterways. While these efforts to collect plastic pollution are laudable, their current capacity and widespread implementation are limited in comparison to their potential and the vast extent of the plastic pollution problem. Similarly, few technologies attempt to prevent plastic pollution leakage, and those that do are limited in scope. A comprehensive approach is needed that combines technology, policymaking, and advocacy to prevent further plastic pollution and the subsequent damage to aquatic ecosystems and human health.
Marine debris on the seafloor has not been thoroughly investigated, and there is little information compared to other types of marine debris. We conducted bottom trawl surveys to determine the present situation of marine debris on the seafloor in offshore areas around Japan. The survey was conducted in three sea areas with different characteristics. As a result, it was found that the amount of marine debris in submarine canyons (2926.1 items/km2) was higher than on the continental shelf. It was revealed that most marine debris on the seafloor is comprised of plastic products, and that debris on the seafloor retains its condition for a long time (over 30 years) without deterioration. In addition, the type of marine debris is affected by the industries operating in each area. Continuing to investigate marine debris on the seafloor in more areas will contribute to solving the problem of marine debris.
Microplastics (MPs) can be ingested by marine organisms directly or indirectly through trophic transfer from contaminated prey. In the marine ecosystem, zooplankton are an important link between phytoplankton and higher trophic levels in the marine food web. Among them, copepods and gelatinous species have been recently reported to ingest MPs, but no potential MP transfer has been verified yet. In this study, a simplified two-level trophic chain – formed by nauplii of the Tigriopus fulvus copepod as prey, and the ephyrae stage of Aurelia sp. as predator – was selected to investigate MP trophic transfer. The experimental setup consisted in feeding ephyrae with nauplii previously exposed to fluorescent 1–5 μm polyethylene MPs and evaluating two ecotoxicological end-points: jellyfish immobility and pulsation frequency. After 24 h, the jellyfish ingested nauplii contaminated with MPs; however, neither immobility nor behavior was affected by MP transfer. These findings show that MPs can be transported at different trophic levels, but more research is needed to identify their potential effects on the marine food web.
While the ubiquity and rising abundance of microplastic contamination is becoming increasingly well-known, there is very little empirical data for the scale of their historical inputs to the environment. For many pollutants, where long-term monitoring is absent, paleoecological approaches (the use of naturally-accumulating archives to assess temporal trends) have been widely applied to determine such historical patterns, but to date this has been undertaken only very rarely for microplastics, despite the enormous potential to identify the scale and extent of inputs as well as rates of change. In this paper, we briefly assess the long-term monitoring and paleoecological microplastic literature before considering the advantages and disadvantages of various natural archives (including lake and marine sediments, ice cores and peat archives) as a means to determine historical microplastic records, as well as the range of challenges facing those attempting to extract microplastics from them. We also outline some of the major considerations in chemical, physical and biological taphonomic processes for microplastics as these are critical to the correct interpretation of microplastic paleoecological records but are currently rarely considered. Finally, we assess the usefulness of microplastic paleoecological records as a stratigraphic tool, both as a means to provide potential chronological information, as well as a possible marker for the proposed Anthropocene Epoch.