Monitoring anthropogenic particles in the environment: Recent developments and remaining challenges at the forefront of analytical methods

Trapping of microplastics and other anthropogenic particles in seagrass beds: Ubiquity across a vertical and horizontal sampling gradient

Seagrass beds can trap large amounts of marine debris leading to areas of accumulation, known as 'sinks', of anthropogenic particles. While the presence of vegetation can enhance accumulation, less is known about how the trapping effect changes from vegetated to less vegetated patches. To test this, vegetation and sediment were sampled along a vegetation percent cover gradient from the centre of seagrass beds to nearby less vegetated patches. To determine whether trapped particles can lead to increased accumulation in associated fauna, gastropods were also collected from the transects laid across this gradient. Extracted anthropogenic particles were counted and characterised. Particles were detected in all sample types and reached quantifiable limits in at least 50% of sediment and gastropod samples. There was no significant difference in the distribution of particles found in seagrass beds compared to less vegetated patches, suggesting other factors contribute to the trapping efficiency of biogenic habitats besides simply the presence or absence of vegetation.

White Stork Pellets: Non-Invasive Solution to Monitor Anthropogenic Particle Pollution

The present study applied a non-invasive method to analyse anthropogenic particles and prey items in white stork (Ciconia ciconia) pellets. Pellets (n = 20) were obtained from white stork nests during the 2020 breeding season from two sites in Croatia. In total, 7869 anthropogenic particles were isolated. The majority of particles were fragments, while previous studies on other birds often reported fibres. An ATR-FTIR polymer analysis detected glass and construction and building materials, as well as several compounds associated with plastic masses. Polymer investigation revealed the presence of dotriacontane and octacosane, which are by-products of polyethylene (PE) degradation and transformation. Additionally, the detection of vinylidene chloride (VDC) highlights the historical contribution of polyvinylidene chloride (PVDC) to plastic pollution. Significant variation in particle quantity and size between the sampling sites was detected, with larger particles found at sites associated with the metal mechanical engineering industry and agriculture. Prey assessment revealed chitin remains of large insects such as Orthoptera and Coleoptera. This research confirms the potential of pellet analysis as a valuable tool for assessing the presence of anthropogenic particles in the environment. However, further research is needed to fully understand the extent of particle ingestion, particle sources and potential impact.

Platinum vaporization-deposition coated polycarbonate membranes for comprehensive, multimodal, and correlative microscopic analysis of micro-and nanoplastics and other environmental particles

Anthropogenic particles, including microplastics, are receiving ever-increasing concern due to their potential environmental impact. Surveys and monitoring require sampling from many environmental and biological matrices, including natural water, drinking water, sediment, and air. However, there are no standard methods for sampling particles in the environment; thereby, many different approaches are used for both single particle and ensemble distribution or bulk chemical analyses. In the microplastics field, particles are often analyzed on membranes using automated analysis with spectroscopic techniques such as Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy. For automated analysis, the filters' properties are crucial. We coated polycarbonate (PC) membranes with 100 nm platinum (Pt) on both side using a e-beam evaporator and evaluated their suitability for filtrating and analysis of environmental samples. The PC membranes have a defined and practical pore size, available in many pore sizes and with circular diameter of 47 mm and 25 mm. Our Pt coated membranes can handle large volumes of fresh and marine waters, high pressure, and various treatment solutions. Moreover, they have good optical properties for imaging with light microscopy (LM) and Scanning Electron Microscopy (SEM), and no disturbing background signal for Raman or FTIR spectroscopy analysis.

First assessment of anthropogenic particle ingestion in Pontellid copepods: Pontella mediterranea as a potential microplastic reservoir in the Neuston

Hyponeustonic species, living at the interface between the atmosphere and the oceans, comprise one of the most understudied and vast critical marine biotope, constantly exposed to high concentrations of anthropogenic contaminants and microplastic (MPs). Copepods of the Pontellidae family represent the primary components of this biotic assemblage worldwide, and their interaction with MPs is still unknown. We studied this interaction for the first time in Pontella mediterranea, assessing the ingestion of anthropogenic particles (APs) in 2793 individuals collected by manta trawl in the Northern Alboran Sea. We observed P. mediterranea abundances ranging from 41.67 to 1174.83 ind/m3, with a mean ingestion of 0.11 APs/ind, predominantly composed of MPs. These results confirm the low ingestion values observed for other copepod taxa. However, given its abundance, this species could retain an average of 45.15 and a maximum of 220 APs per m3 of seawater (APs/m3), mostly composed of cellulose acetate and cotton fibers. The abundances of APs were evaluated in surface (0-12 cm) and sub-surface waters (5 m depth) by combining manta trawl and Continuous Underway Fish Egg Sampler sampling. The AP abundances found (surface waters: 0.67 ± 1.04 APs/m3; subsurface waters: 3.85 ± 2.67 APs/m3) were consistent with those previously observed in the Mediterranean basin, confirming that the ingestion values observed in P. mediterranea are not due to a local accumulation of environmental MPs. Results highlight how this neustonic copepod could represent one of the largest reservoirs of APs within the upper layers of the oceans, representing an entry point for these particles within food webs. Considering the worldwide distribution and abundance of this family of copepods, the results are of environmental concern.

Single entity collision for inorganic water pollutants measurements: Insights and prospects

In the context of aquatic environmental issues, dynamic analysis of nano-sized inorganic water pollutants has been one of the key topics concerning their seriously amplified threat to natural ecosystems and life health. Its ultimate challenge is to reach a single-entity level of identification especially towards substantial amount of inorganic pollutants formed as natural or manufactured nanoparticles (NPs), which enter the water environments along with the potential release of constituents or other contaminating species that may have coprecipitated or adsorbed on the particles' surface. Here, we introduced a 'nano-impacts' approach-single entity collision electrochemistry (SECE) promising for in-situ characterization and quantification of nano-sized inorganic pollutants at single-entity level based on confinement-controlled electrochemistry. In comparison with ensemble analytical tools, advantages and features of SECE point at understanding 'individual' specific fate and effect under its free-motion condition, contributing to obtain more precise information for 'ensemble' nano-sized pollutants on assessing their mixture exposure and toxicity in the environment. This review gives a unique insight about the single-entity collision measurements of various inorganic water pollutants based on recent trends and directions of state-of-the-art single entity electrochemistry, the prospects for exploring nano-impacts in the field of inorganic water pollutants measurements were also put forward.

Refinement of a microfurnace pyrolysis-GC-MS method for quantification of tire and road wear particles (TRWP) in sediment and solid matrices

Tire and road wear particles (TRWP) are produced by abrasion at the interface of the pavement and tread surface and contain tread rubber with road mineral encrustations. Quantitative thermoanalytical methods capable of estimating TRWP concentrations are needed to assess the prevalence and environmental fate of these particles. However, the presence of complex organic constituents in sediment and other environmental samples presents a challenge to the reliable determination of TRWP concentrations using current pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) methodologies. We are unaware of a published study evaluating pretreatment and other method refinements for microfurnace Py-GC-MS analysis of the elastomeric polymers in TRWP including polymer-specific deuterated internal standards as specified in ISO Technical Specification (ISO/TS) 20593:2017 and ISO/TS 21396:2017. Thus, potential method refinements were evaluated for microfurnace Py-GC-MS, including chromatography parameter modification, chemical pretreatment, and thermal desorption for cryogenically-milled tire tread (CMTT) samples in an artificial sediment matrix and a sediment field sample. The tire tread dimer markers used for quantification were 4-vinylcyclohexene (4-VCH), a marker for styrene-butadiene rubber (SBR) and butadiene rubber (BR), 4-phenylcyclohexene (4-PCH), a marker for SBR, and dipentene (DP), a marker for natural rubber (NR) or isoprene. The resultant modifications included optimization of GC temperature and mass analyzer settings, along with sample pretreatment with potassium hydroxide (KOH) and thermal desorption. Peak resolution was improved while minimizing matrix interferences with overall accuracy and precision consistent with those typically observed in environmental sample analysis. The initial method detection limit for an artificial sediment matrix was approximately 180 mg/kg for a 10 mg sediment sample. A sediment and a retained suspended solids sample were also analyzed to illustrate the applicability of microfurnace Py-GC-MS towards complex environmental sample analysis. These refinements should help encourage the adoption of pyrolysis techniques for mass-based measurements of TRWP in environmental samples both near and distant from roadways.

The Chubut River estuary as a source of microplastics and other anthropogenic particles into the Southwestern Atlantic Ocean

This is the first report of anthropogenic particles (APs), including microplastics and synthetic, semi-synthetic and anthropogenically-altered natural fibers, in water and sediment of the Chubut River estuary. This river is the main source of freshwater in Chubut Province (Patagonia, Argentina), where wastes and pollutants are poured and finally end in the Atlantic Ocean. The average concentration in surface and bottom water samples was 5.5 items/L, while in sediment was 175.4 items/kg dw. Raman's analysis identified particles dominated by polyethylene terephthalate (PET) (35.5 %), dye signature only (18.5) and anthropogenic cellulose (10 %). Fibers were the prevalent shape (83 %), and the chemical identification evidenced a textile origin. The highest APs concentration was found in sediments from the site with the finest grain size and the greatest amount of organic matter. Present results will provide a baseline for future studies and raise public and governmental awareness.

Comparison of pre-treatment methods and heavy density liquids to optimize microplastic extraction from natural marine sediments

The ubiquitous occurrence of anthropogenic particles, including microplastics in the marine environment, has, over the last years, gained worldwide attention. As a result, many methods have been developed to estimate the amount and type of microplastics in the marine environment. However, there are still no standardized protocols for how different marine matrices should be sampled or how to extract and identify these particles, making meaningful data comparison hard. Buoyant microplastics are influenced by winds and currents, and concentrations could hence be expected to be highly variable over time. However, since both high density and most of the initially buoyant microplastics are known to eventually sink and settle on the seafloor, marine sediments are proposed as a suitable matrix for microplastics monitoring. Several principles, apparatuses, and protocols for extracting microplastics from marine sediments have been presented, but extensive comparison of the different steps in the protocols using real environmental samples is lacking. Thus, in this study, different pre-treatment and subsequent density separation protocols for extraction of microplastics from replicate samples of marine sediment were compared. Two pre-treatment methods, one using inorganic chemicals (NaClO + KOH + Na₄P₂O₇) and one using porcine pancreatic enzymes, as well as one with no pre-treatment of the sediment, were compared in combination with two commonly used high-density saline solutions used for density separation, sodium chloride (NaCl) and zinc chloride (ZnCl₂). Both pre-treatment methods effectively removed organic matter, and both saline solutions extracted lighter plastic particles such as polyethylene (PE) and polypropylene (PP). The most efficient combination, chemical pre-treatment and density separation with ZnCl₂, was found to extract > 15 times more particles (≥ 100 µm) from the sediment than other treatment combinations, which could largely be explained by the high presence and efficient extraction of PVC particles.

Do poly(lactic acid) microplastics instigate a threat? A perception for their dynamic towards environmental pollution and toxicity

Fears concerning microplastics (MPs) environmental fate and persistence are progressively expanding on a global basis, with the emphasis given to manufacturing bioplastics for substituting petro-derived plastics extensively growing. Among them, poly(lactic acid) (PLA) holds a pioneering role towards the replacement of conventional polymeric materials, owing to its multifunctional properties, enclosing superior mechanical properties, low cost, renewability, great biocompatibility, transparency, and thermoplasticity launching many fields of application. Due to the wide applicability of PLA in several sectors of everyday life, its waste to be released into the environment is expected to follow a growing tendency during the upcoming years. Even though PLA is a biodegradable polyester, it actually degrades under specific composting environments, including a rich oxygen environment with high temperatures (58-80 °C), high humidity (>60% moisture) as well as the presence of micro-organisms (thermophilic bacteria). Additionally, in various studies it has been implied that PLA displays slower degradation performance when found in blends with other conventional polymers, underlining the unspecified effects on PLA degradation profile, keeping thus the information about PLA degradation from a blur standpoint. Therefore, a deepened understanding of the fate and dynamic effects of PLA MPs is of primary importance. Nevertheless, the current examination of the effects of PLA MPs in terms of sorption capacities and toxicity is so far limited and broadly unexplored since the current scientific emphasis has been merely centered on the conventional MPs' behavior. In this light, the present review provides an inclusive overview of the ongoing research of poly(lactic acid) in the framework of microplastics' pollution, while the future trends and missing points in this context are highlighted.