Plasticizer Content Research Articles

Plastic waste in dense asphalt mixes for road pavements

Recycling plastic waste in asphalt pavements records increasing statistic figures of application during the last decade worldwide. Due to environmental constraints, but also, to some beneficial properties of plastic waste, recycling in asphalt tends to become current practice, in several countries. In the Aristotle University of Thessaloniki (AUTH), the first attempt to produce asphalt mix using plastic waste consisted of mixing recycled plastic flakes with non-modified binder. Following an asphalt mix design in the laboratory, the whole mass of conventional aggregates was replaced by PET flakes. Recycled PET flakes were chosen to be introduced in the asphalt mix since they are hard, resilient and water repellent. Bitumen emulsion was first preferred as a binder to produce a cold asphalt mix. At a second stage of experimental research, plastic flakes replaced a part of the limestone sand while conventional asphalt 50/70 was used as a binder. At this stage, the experimental research provided more encouraging outcomes. Stability of asphalt mixes decreases as the plastics content in the mix increases, but all recorded values were still within limits of acceptance. At a third stage of research, LDPE recycled material of fine gradation was used to replace a part of the asphalt binder in dense mixes. The objective was to produce a modified binder and a more durable asphalt structure. Test results showed a significant improvement of the performance of asphalt mixes, in terms of strength and deformability of the asphalt mix structure. The research is completed by comparing the conventional techniques with the outcomes of the recycling process and by delineating potential fields of application of the recycled plastics in asphalt pavements.

Machine Learning Based Prediction of Compressive and Flexural Strength of Recycled Plastic Waste Aggregate Concrete

In the last 50 years, the use of plastics has increased significantly due to advances in technology, population growth and increasing needs. However, this trend has led to the accumulation of large amounts of plastic waste. Numerous studies have been conducted on the use of recycled plastic materials in concrete production as a means of recycling and environmental protection. This study aims to predict the 28-day cylinder compressive and flexural strength of concretes using Polyethylene Terephthalate (PET), Phenolic Formaldehyde (PF), Polypropylene (PP), Polycarbonate (PC), Polyvinyl Chloride (PCV), High-Impact Polystyrene (HIPS) and High-Density Polyethylene (HDPE) plastic waste as aggregates. In this scope, a comprehensive database was created using experimental results obtained from the literature. Then, this study used six ML models, including Support Vector Regressor (SVR), Random Forest Regressor (RFR), Gradient Boosting Regressor (GBR), XGBoost Regressor (XGR), LightGBM Regressor (LGR), Bagged Decision Trees Regressor (BDTR), to predict the compressive and flexural strength of recycled plastic waste aggregate concrete (RPWAC). From the experimental database, 253 data points with strength between 6.00-70.05MPa were identified to estimate the compressive strength (CS) and 175 data points with strength between 1.21-7.96MPa were identified for flexural strength (FS). Cross-validation was used for six ML models and hyperparameter fine-tuning was performed. The results showed that six different ML models predicted the compressive and flexural strengths of RPWAC with high accuracy. The XGR model predicted CS and FS better than the other five different models with R2 values of 0.931 and 0.999, respectively. The three main properties effecting the CS of RPWAC were plastic waste content, water/cement ratio and concrete specific gravity, while the three main properties affecting the FS of RPWAC were cement specific gravity, plastic waste content and cement CS.

The Effect of Plasticizer Type and Concentration on Cellulose Acetate-Based Bioplastic from Durian Skin

The Effect of Plasticizer Type and Concentration on Cellulose Acetate-Based Bioplastic from Durian Skin

Establishing a plastic waste map using remote sensing data in the coastal area of Thanh Hoa province (Vietnam)

Plastic pollution, particularly in oceans, is a growing environmental threat. Monitoring this pollution is challenging due to the shortage of data and tools. Remote sensing offers a promising solution by using various types of satellite and aerial images to detect and track plastic waste movement. Purpose. The study aims to establish a plastic waste map using remote sensing technology, focusing on the case study of the coastal area of Thanh Hoa province, Vietnam. Methodology. The study involves several steps, including the collection of plastic waste data (samples in the case study and indices from remote sensing images) as well as topographic and base map collection, statistics of plastic samples, grid design, calculation, interpolation, accuracy assessment, and mapping. Field surveys involved taking pictures of plastic debris along designated routes and a grid system was used to classify and calculate waste samples. Satellite images, especially Sentinel-2 MSI optical satellite imagery, are utilized to identify water areas of high plastic concentration. Findings. A map of plastic wastes in coastal areas of Thanh Hoa was created, with indices like NDWI (Normalized Difference Water Index) and FDI (Floating Debris Index) helping identify potential plastic waste signals. The resulting map reveals high concentrations of plastic waste in sea areas near the major river mouths of the Ma River basin and tourist areas, which aligns with areas of high human activity. Originality. This is the first study of plastic waste in the coastal area using remote sensing data in Thanh Hoa province, Vietnam. Practical value. This study can contribute to the effective management of marine plastic waste in Thanh Hoa while opening up opportunities for applying the method to create marine plastic waste maps throughout Vietnam and foster long-term monitoring and management.

Assessing the detection of floating plastic litter with advanced remote sensing technologies in a hydrodynamic test facility.

Remote sensing technologies have the potential to support monitoring of floating plastic litter in aquatic environments. An experimental campaign was carried out in a large-scale hydrodynamic test facility to explore the detectability of floating plastics in ocean waves, comparing and contrasting different microwave and optical remote sensing technologies. The extensive experiments revealed that detection of plastics was feasible with microwave measurement techniques using X and Ku-bands with VV polarization at a plastic threshold concentration of 1 item/m2 or 1-10g/m2. The optical measurements further revealed that spectral and polarization properties in the visible and infrared spectrum had diagnostic information unique to the floating plastics. This assessment presents a crucial step towards enabling the detection of aquatic plastics using advanced remote sensing technologies. We demonstrate that remote sensing has the potential for global targeting of plastic litter hotspots, which is needed for supporting effective clean-up efforts and scientific evidence-based policy making.

The Influence of the Type and Concentration of Plasticizer on the Properties of Biopolymer Films based on Wild Flax (Camelina Sativa)

The development of biodegradable packaging materials using naturally occurring, renewable biopolymers has gained attraction due to consumer demand for high-quality products and concerns about environmental waste problems. However, the inferior mechanical properties and low water resistance of packaging materials based on natural polymers pose a significant obstacle to their wider use. One of the ways to improve the properties of biopolymer-based packaging materials is the addition of plasticizers during their synthesis. In this work, the influence of the type and concentration of plasticizer on the properties of new biopolymer films based on wild flax (Camelina sativa) was investigated. Camelina sativa oil cake (CSoC) remains after edible oil cold pressing as a by-product. One of the possibilities for its valorization is the synthesis of biopolymer materials. During the synthesis, different plasticizers - glycerol and polyethylene glycol 400 - were added in different concentrations - 20%-60%. The obtained CSoC-based biopolymer films were analyzed for the following properties: Moisture content, solubility, thickness, tensile strength, elongation at break, and water vapor permeability. The results obtained showed significant differences when different plasticizers were applied at different concentrations. The biopolymer film with optimal properties was obtained by adding glycerol at a concentration of 40%.

Unscrambling why plastics aren’t detectable in chicken eggs

Several food groups have been reported to contain varying concentrations of plastics. This study was designed to quantitatively investigate for the first time in Australia the presence of plastics in store-bought chicken eggs. Three commonly consumed brands of free-range, free-range organic, barn-laid and backyard (home-laid) chicken egg samples were analyzed for seven common polymers (i.e., polypropylene, polyethylene, polyvinyl chloride, polyethylene terephthalate, polystyrene, poly-(methylmethacrylate) and polycarbonate)). Samples were extracted by enzyme digestion and pressurized liquid extraction, followed by quantitative analysis through double-shot microfurnace pyrolysis coupled to gas chromatography-mass spectrometry. No plastics were detected at concentrations >limit of detection (LOD) (from 0.04 μg/g for PS to 0.22 μg/g for PVC) in the egg samples analyzed, regardless of brand and category, suggesting limited exposure of Australians to plastics from consuming eggs This study provides valuable baseline data and underscores the importance of continued monitoring to ensure the safety and integrity of food supplies in the face of rising environmental plastic pollution.

Evaluation of Polymer Inclusion Membrane Containing Copoly Eugenol Divinyl Benzene 10% as a Carrier for Phenol Transport

Phenol is a toxic and organic compound that often contaminates water, posing significant environmental hazards. To resolve this issue, we conducted research on phenol transport using the Polymer Inclusion Membrane (PIM) method, employing Copoly Eugenol Divinyl Benzene (Co-EDVB) 10% as a carrier compound. The primary objective of this research was to assess the stability and capability of the PIM membrane. Our findings revealed that membrane stability was achieved with a plasticizer concentration of 3.32%. The addition of NaNO3 salt to the source phase yielded the most promising outcomes compared to other types of salt, facilitating the transport of 85.84% of phenol. When NaNO3 0.01 M was introduced in both the source and receiving phases, the transport efficiency increased to 89.93% and 86.76%, respectively. In order to evaluate the durability of the PIM membrane during repeated use, transportation experiments were conducted five times. Without washing, the membrane successfully transported phenol in amounts of 72.19%, 69.23%, 62.71%, 55.91%, and 48.16% during each successive run. Conversely, with regular washing, the membrane maintained its transport efficiency, achieving 70.85%, 64.10%, 56.72%, 49.26%, and 27.19% for each cycle. Notably, the membrane's lifetime reached only 29 days without the addition of 0.1 M NaNO3 salt. However, with the inclusion of NaNO3 0.1 M salt, its longer extended to 58 days.

Simultaneous analysis of several plasticizer classes in different matrices by on-line turbulent flow chromatography-LC-MS/MS.

The development of methodologies for the determination of plasticizers is essential for assessing the environmental and human impact resulting from the use of plastics. A fast analytical method with on-line purification based on turbulent flow chromatography (TFC) coupled to tandem mass spectrometry (MS-MS) has been developed for the analysis of ten phthalates, four alternative plasticizers (including adipates and citrates), and 20 organophosphate esters (OPEs). The method has been validated for the determination of plasticizers across different matrices. Analytical parameters showed acceptable recoveries ranging between 50 and 125%, RSDs lower than 20%, and mLODs of 0.001-2.08ngg-1 wet weight (ww), 0.002-0.30ngg-1, and 0.001-0.93ngm-3 for foodstuffs, face masks, and ambient air, respectively. These methodologies were applied to foodstuff samples purchased in grocery stores, reusable and self-filtering masks, and indoor air measured in different locations. Plasticizers were detected in all the analyzed samples, with values up to 22.0μgg-1 ww, 6.78μgg-1, and 572ngm-3 for foodstuffs, face masks, and indoor air, respectively. The contribution of each family to the total plasticizer content varied between 1.3 and 87%, 0.5 and 98%, and 0.5 and 65% for phthalates, alternative plasticizers, and OPEs, respectively. These findings highlighted the need for analytical methodologies capable of simultaneously assessing a wide number of plasticizers with minimal extractionsteps. This capability is crucial in order to obtain more conclusive insights into the impact of these pollutants on both the environment and human health, arising from different sources of exposure such as foodstuffs, plastic materials, and atmospheric air.

Shell Materials for Chewable Capsules, From Design of Experiments to Optimal Dosage Form Manufacturing

AbstractInnovations in chewable dosage forms provide solutions for swallowing difficulties faced by certain patient populations. Chewable softgel capsules (SGC) offer opportunities to expand the benefits of SGC, excelling in the delivery of lipid‐based formulations by optimizing the mechanical properties of the shell material without compromising industrial‐scale manufacturing. This study employs an original approach, with a target product profile that aims to combine processability and chewability, to develop optimized chewable dosage forms. Through a mixture design of experiments, key factors such as plasticizer content and the addition of acid‐modified thin‐boiling corn starch are explored, focusing on response parameters critical to achieving the desired properties of the capsule shell material. Optimal shell compositions—one starch‐free and another containing 9% w/w starch, with respective gelatin/non‐volatile plasticizer ratios of 0.81 and 0.67 are determined and evaluated by manufacturing chewable SGC at pilot scale using rotary die technology. The successful manufacturing and resulting capsules, which exhibit the intended properties, highlight the efficiency of this approach in striking the right balance between processability, soft texture, and quick disintegration time.

Biochar Production From Plastic‐Contaminated Biomass

ABSTRACTAnaerobic digestion and composting of biowastes are vital pathways to recycle carbon and nutrients for agriculture. However, plastic contamination of soil amendments and fertilizers made from biowastes is a relevant source of (micro‐) plastics in (agricultural) ecosystems. To avoid this contamination, plastic containing biowastes could be pyrolyzed to eliminate the plastic, recycle most of the nutrients, and create carbon sinks when the resulting biochar is applied to soil. Literature suggests plastic elimination mainly by devolatilization at co‐pyrolysis temperatures of > 520°C. However, it is uncertain if the presence of plastic during biomass pyrolysis induces the formation of organic contaminants or has any other adverse effects on biochar properties. Here, we produced biochar from wood residues (WR) obtained from sieving of biowaste derived digestate. The plastic content was artificially enriched to 10%, and this mixture was pyrolyzed at 450°C and 600°C. Beech wood (BW) chips and the purified, that is, (macro‐) plastic‐free WR served as controls. All biochars produced were below limit values of the European Biochar Certificate (EBC) regarding trace element content and organic contaminants. Under study conditions, pyrolysis of biowaste, even when contaminated with plastic, can produce a biochar suitable for agricultural use. However, thermogravimetric and nuclear magnetic resonance spectroscopic analysis of the WR + 10% plastics biochar suggested the presence of plastic residues at pyrolysis temperatures of 450°C. More research is needed to define minimum requirements for the pyrolysis of plastic containing biowaste and to cope with the automated identification and determination of plastic types in biowaste at large scales.

Impacts of plastic pollution on soil–plant properties and greenhouse gas emissions in wetlands: A meta-analysis

Plastic pollution in wetlands has recently emerged as an urgent environmental problem. However, the impacts of plastic contamination on soil-plant properties and greenhouse gas (GHG) emissions in wetlands remain unclear. Thus, this study conducted a meta-analysis based on 44 study sites to explore the influence of plastic pollution on soil physicochemical variables, soil microorganisms, enzyme activity, functional genes, plant characteristics, and GHG emissions (CO2, CH4, and N2O) in different wetland types. Based on the collected dataset, the plastic pollution significantly increased soil organic matter and organic carbon by on average 28.9 % and 34.2 %, respectively, while decreased inorganic nutrient elements, bacteria alpha diversity and enzyme activities by an average of 5.9 −14.2 %. The response of bacterial abundance to plastic pollution varied depending on phylum classes. Plant biomass and photosynthetic efficiency were decreased by an average of 12.8 % and 18.4 % due to plastic pollution. The concentration and exposure time of plastics play a key role in influencing the soil and plant properties in wetlands. Furthermore, plastic exposure notably increased the abundance of the functional genes related to C degradation and the ammonia oxidizing microorganisms, and the consequent CO2 and N2O emissions (with effect sizes of 2.10 and 1.94, respectively). We also found that plastic concentrations and exposure duration affected the wetland soil–plant system. Our results might be helpful to design further investigations on plastic effects and develop appropriate measures for mitigating plastic pollution in wetlands.

Plasticizers: distribution and impact in aquatic and terrestrial environments.

Plasticizers, essential additives for enhancing plastic properties, have emerged as significant environmental and health concerns due to their persistence and widespread use. This study provides an in-depth exploration of plasticizers, focusing on their types, structures, properties, production methods, environmental distribution, and associated risks. The findings reveal that petroleum-based phthalates, particularly di-(2-ethylhexyl) phthalate (DEHP), are prevalent in aquatic and terrestrial environments, primarily due to the gradual degradation of plastic polymers. In the analysis of 39 studies on water contamination during the period of 2022-2023, only 22 works could be extracted due to insufficient details on the numerical value of plasticizer concentrations. Similarly, soil and sediment contamination studies were fewer, with only 11 studies focusing on sediments. These studies reveal that high plasticizer concentrations, notably in industrial and urban areas, often exceed recommended environmental limits, posing risks to ecological integrity and human health through bioaccumulation. Bioaccumulation of these compounds in soil and water could negatively affect the microbial communities, nutrient cycling, and could destabilize the overall ecological integrity. Concerns about their direct uptake by plants and potential risks to human health and food safety are highlighted in this study due to the high concentrations exceeding the threshold values. The review evaluates current treatment technologies, including metal-organic frameworks, electrochemical systems, multi-walled carbon nanotubes, and microbial degradation, noting their potential and challenges related to cost and energy consumption. It underscores the need for improved detection protocols, cost-effective treatments, stricter regulations, public awareness, and collaborative research to mitigate the adverse impacts of plasticizers on ecosystems and human health.

Effect of succinonitrile on the structural, ion conductivity, and dielectric properties of PVDF‐HFP based solid polymer electrolytes

AbstractA detailed account of the poly(vinylidene difluoride‐co‐hexafluoropropylene) (PVDF‐HFP)/succinonitrile (SN)/lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) based solid polymer electrolytes (SPEs) of various compositions is reported. SN is incorporated as plasticizer, while LiTFSI is employed as the source of lithium ions. Fourier transfer infrared (FTIR) spectroscopy reveals the formation of polar and electroactive γ crystal phase by PVDF in pristine PVDF‐HFP and the prepared SPE films. FTIR further confirms the interaction between the host polymer and the salt and between the salt and the plasticizer. The interaction between the salt and plasticizer suggests that SN not only offers the plasticization effect but also facilitates salt dissociation. The ion conductivity increases with increasing salt content up to 20 wt% but beyond that concentration a decline in ion conductivity is observed, which could be attributed to the ion pair association or cluster formation due to the excess salt concentration that reduces the availability of free ions and ultimately leads to the reduction in ion conductivity. After including SN in the SPE formulation, electrochemical impedance spectroscopy reveals a substantial increase in room temperature ion conductivity of the SPE from ~1.08 × 10−5 S cm−1 for pristine SPE with 20 wt% salt to ~2.7 × 10−4 S cm−1 for plasticized SPE with 40 wt% SN and 20 wt% salt. This is attributed to the plasticizing effect of SN that enhances ion mobility through the matrix and to the increased charge carrier concentration (SN facilities salt dissociation). The fabricated SPEs exhibit a significant enhancement in ion conductivity with increasing temperature and the maximum ion conductivity of 1.1 × 10−3 S cm−1 is attained at 393 K by plasticized SPE with 40 wt% SN content. The ion conductivity of all the prepared SPEs follows the temperature dependent Arrhenius behavior, suggesting the thermally activated ion hopping mechanism of ionic conduction. Further, the plasticized SPEs display near unity ion transference number indicating the predominance of the ionic mode of conduction. The dielectric and electric modulus analysis reveal a faster relaxation phenomenon and hence higher ion conductivity of the prepared SPEs with increasing salt and plasticizer content.

Plastic debris exposure and effects in rivers: Boundaries for efficient ecological risk assessment.

Until recently, plastic pollution research was focused on the marine environments, and attention was given to terrestrial and freshwater environments latter. This discussion paper aims to put forward crucial questions on issues that limit our ability to conduct reliable plastic ecological risk assessments in rivers. Previous studies highlighted the widespread presence of plastics in rivers, but the sources and levels of exposure remained matters of debate. Field measurements have been carried out on the concentration and composition of plastics in rivers, but greater homogeneity in the choice of plastic sizes, particularly for microplastics by following the recent ISO international standard nomenclature, is needed for better comparison between studies. The development of additional relevant sampling strategies that are suited to the specific characteristics of riverine environments is also needed. Similarly, we encourage the systematic real-time monitoring of environmental conditions (e.g., topology of the sampling section of the river, hydrology, volumetric flux and velocity, suspended matters concentration) to better understand the origin of variability in plastic concentrations in rivers. Furthermore, ingestion of microplastics by freshwater organisms has been demonstrated under laboratory conditions, but the long-term effects of continuous microplastic exposure in organisms are less well understood. This discussion paper encourages an integrative view of the issues involved in assessing plastic exposure and its effects on biota, in order to improve our ability to carry out relevant ecological risk assessments in river environments.

Dependence of Density, Hardness, Strength, and Dimensions of WC–15 Co Hard Alloy Samples on the Plasticizer Content in Workpieces Obtained Using a Plastic Mold Made by 3D Printing

Dependence of Density, Hardness, Strength, and Dimensions of WC–15 Co Hard Alloy Samples on the Plasticizer Content in Workpieces Obtained Using a Plastic Mold Made by 3D Printing

INTERLAYER EFFECT ON DEFORMATION AND FRACTURE OF DENDRITIC STRUCTURE FORMED DURING WIRE-FEED ELECTRON-BEAM ADDITIVE MANUFACTURING OF AL-SI ALLOY

Interfaces and surfaces play an important role in tribology, mechanics and materials science, causing plastic strain localization and stress concentration of different spatial scales. The interfacial inhomogeneity is highly pronounced in 3D printed materials due to thermo-cycling and layer-by-layer building. In this paper, the inlayer and interlayer structure of a eutectic Al-Si alloy fabricated by wire-feed electron-beam additive manufacturing is investigated by optical and electron microscopy. Model structures inheriting the experimental morphology are created, and their deformation and fracture are simulated using ABACUS/Explicit, with the user-defined subroutines being developed to describe the constitutive behavior of aluminum dendrite, silicon and eutectic materials. A two-scale computational approach is implemented to study the influence of the interlayer formed in the heat-affected zone on the dendritic structure strength.

Synthesis and Characterization of Shungite Modified Poly-N-Ninylpyrrolidone-Agarose Composites for Medical Application.

A systematic investigation was conducted to synthesize hybrid composite materials that use synthetic poly-N-vinylpyrrolidone and natural (agar-agar) macromolecules with plasticizers (PEG-400) and mineral filler shungite by means of electron irradiation. The XRD and SEM data showed that the structure of the resulting hybrid composites is an interpenetrating network with distributed particles of mineral component. It has been established that the mechanical properties of hybrid composites are determined mainly by the structural organization of the interpenetrating polymer network formed under electron irradiation of the initial synthetic and natural polymer mixture in the presence of plasticizers, as well as by the conditions for intercalation of polymer segments into the mineral matrix and vice versa. It has been revealed that the degree of swelling of hybrid composites strongly depends on the concentration of a low-molecular plasticizer in the polymeric interpenetrating network, which easily impregnates into the matrix of shungite. Successfully obtained [PVP-AA-PEG] hydrogels with shungite can be applied in regenerative medicine as wound healing dressings.

Influence of Plasticizers Concentration on Thermal, Mechanical, and Physicochemical Properties on Starch Films

The increasing demand for sustainable packaging materials has driven the exploration of biodegradable alternatives to synthetic plastics. This study investigates the thermal and mechanical properties of starch-based films plasticized with varying concentrations of glycerol and sorbitol. Cornstarch films were prepared with glycerol and sorbitol plasticizers in different ratios, and their physical characteristics, including swelling index, water solubility, and thermal stability, were assessed using Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and tensile testing. The results indicate that the incorporation of plasticizers significantly influenced the films’ properties. Films with higher glycerol content exhibited greater flexibility and solubility, while sorbitol-plasticized films showed enhanced thermal stability. The combination of both plasticizers yielded films with balanced properties suitable for food packaging applications. This study demonstrates the potential of glycerol and sorbitol as effective plasticizers in developing biodegradable starch-based films, offering a promising alternative to conventional plastic packaging.

Bioindicator species of plastic toxicity in tropical environments

In French Polynesia, pearl farming represents the second economic resource of the country. The distinctive black pearls produced there are globally recognized and appreciated. However, pearl farms extensively use submerged plastic materials. Through gas chromatography coupled with tandem mass spectrometry detection (GC/MSMS) analysis, we were able to identify various POPs (Persistent Organic Pollutants) and additives released after 24 h of leaching into seawater from these “pearl plastics” composed of PE (Polyethylene) and PP (Polypropylene). Subsequently, we tested different concentrations of this plastic leachate on five tropical species commonly raised in the pearl and aquaculture sector in Polynesia: Pinctada margaritifera, Saccostrea cucullata, Holothuria whitmaei, Litopenaeus stylirostris, and Tripneustes gratilla. Monitoring the embryo-larval development of these organisms allowed us to establish a correlation between the decrease in the percentage of normal larvae and the plastic concentration. Through the use of regression models, the EC50 (Effective Concentration) of the plastic leachate for each species was determined, and demonstrated to range from 6.6 to 71.5 g/L, depending on the species. The most sensitive species was the black teatfish Holothuria whitmaei, a tropical sea cucumber used for the first time for ecotoxicological tests. The sensitivity of this species, its large distribution in tropical areas, and the various advantages presented by its cultivation make it an interesting bio-indicator species for monitoring plastic pollution in tropical lagoons.