Geochemical signatures in plastic debris from the Curonian Lagoon, Lithuania

Sajjad Abbasi; Neda Hashemi; Patryk Oleszczuk; Viktorija Sabaliauskaitė; Nerijus Dzingelevičius; Arūnas Balčiūnas; Rita Vaičekauskaitė; Reda Dzingelevičienė

doi:10.1371/journal.pone.0340582

Abstract

This study examined elemental accumulation on weathered plastic waste as a contributor to environmental pollution. Twenty-five plastic samples collected near the Curonian Lagoon in Lithuania were analyzed for 32 elements using inductively coupled plasma-mass spectrometer (ICP-MS). Five common polymers (polyethylene, polypropylene, Polyethersulfone, polyester, and polyethylene terephthalate) were identified, with polyethylene exhibiting the highest elemental uptake, followed by polypropylene and polystyrene. Correlation analysis suggested relationships between elemental uptake and geochemical behavior, with alkali and alkaline earth elements (REEs) potentially enhancing the uptake of intermediate ions. However, elements such as sulfur, lead, cadmium, and antimony showed limited correlation with other elements. Despite their low mobility, REEs were used to infer sources of pollution, and the aluminum to lanthanum ratio was proposed as a potential indicator of possible anthropogenic pollution from industrial, petroleum, and vehicle emissions.

Citation: Abbasi S, Hashemi N, Oleszczuk P, Sabaliauskaitė V, Dzingelevičius N, Balčiūnas A, et al. (2026) Geochemical signatures in plastic debris from the Curonian Lagoon, Lithuania. PLoS One 21(2): e0340582. https://doi.org/10.1371/journal.pone.0340582

Editor: Renjith VishnuRadhan, Amity University Amity Institute of Biotechnology, INDIA

Received: July 28, 2025; Accepted: December 23, 2025; Published: February 2, 2026

Copyright: © 2026 Abbasi et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: We have made the dataset publicly available on Zenodo (DOI: https://doi.org/10.5281/zenodo.18093949).

Funding: Research Council of Lithuania (LMTLT), agreement No. S-MIP-23-139 The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Introduction

Plastics have become indispensable to modern society since their inception in the early 20th century, with global production soaring to over 400 million tons as of 2024 [1]. However, the durability that makes these materials useful also contributes to a pervasive environmental crisis, as mismanaged plastic waste increasingly contaminates aquatic ecosystems [2–5]. Common polymers in aquatic environments like polyethylene, polypropylene and polystyrene, are not merely physical pollutants; they are chemically active particles that contain hazardous additives and, once in the environment, act as vectors for a wide range of pollutants [6–9].

The role of plastics as pollutant vectors is twofold. First, they can release inherent chemical ingredients, including organic additives and, as recently identified, rare earth elements (REEs) which have been proposed as tracers for electronic waste in plastics [10–12]. Second, and perhaps more significantly, their surfaces efficiently sorb exogenous contaminants from the surrounding environment. These include toxic elements [9] and persistent organic pollutants such as PCBs, PAHs, and antibiotics [13]. This sorptive capacity is dramatically enhanced by environmental aging and weathering, which increase the surface area and reactivity of plastic debris [14–16]. The adsorption processes are governed by various mechanisms, including hydrophobic interactions, van der Waals forces, and pore filling, dictated by the physicochemical properties of both the polymer and the contaminant [17,18].

The risk posed by plastic adsorbed contaminants is particularly acute in sensitive and enclosed aquatic systems, such as coastal lagoons and wetlands. These ecosystems, often separated from the open sea by spits or barrier islands, are highly susceptible to pollution accumulation from diverse anthropogenic sources, industrial effluents and oil pollution, vehicle emissions, agricultural activities, and tourism [2,9,12,19–22]. In confined systems, the interaction of pollutants with plastic particles can extend the residence time and bioavailability of toxins, increasing their potential to enter the food web and magnify ecological risks [6].

The Curonian Lagoon, the largest coastal lagoon in Europe, represents a critical case study of such pressures. As a protected area of high ecological and economic value [23], it faces significant pollution inputs from oil activities in its northern section, agricultural practices in its watershed, and tourism [19,24]. Existing research has documented both plastic pollution and elemental contamination in the region. For instance, atmospheric deposition has been identified as a major pathway for Microplastics influx (27.8 × 10¹² MP year ⁻ ¹), far exceeding riverine input (20.7 × 10⁹ MP year ⁻ ¹) [19], with high concentrations (60.3 MP L^-1) also found in ice cores [25]. Older studies have been conducted on the evaluation of toxic elements. Prior research indicates significant anthropogenic enrichment of toxic elements (Cd, Cu, Pb, As) in lagoon sediments, mainly from the northern part and Klaipėda port [26–28].

While research on elemental adsorption onto plastics is expanding in both field [15,19,29,30] and laboratory settings [6,31–33], a critical gap remains in understanding the accessible fraction of these adsorbed elements, the portion that is potentially bioavailable. Traditional methods involving strong acid digestion of the entire plastic matrix can introduce contamination and overestimate risk by measuring elements locked within the polymer itself. Therefore, this study examines the bioavailable fraction and potential risks of elements adsorbed onto plastic debris from the Curonian Lagoon. We used ICP-MS with a modified BCR sequential extraction (0.11 M acetic acid [34]), previously applied in our study [6], to analyze the bioavailable elemental phase. This approach enables a more environmentally relevant analysis of polymer adsorption behavior. Additionally, the study employs a geochemical approach to explore potential contamination sources using REE signatures on plastic surfaces.

Materials and methods

Sample collection and polymer identification

Twenty-five deteriorated plastic pieces, identified by physical damage, discoloration, or adhered sediment, were collected from the Curonian Lagoon, Lithuania, on September 18, 2024. Sampling was conducted within a 100–200 m radius of sites previously studied by Abbasi et al. [19], with permission granted by Klaipėda University. Items ranged from 1 to 6 cm and were transported in glass containers. Loosely adhered debris were removed by gentle agitation in deionized water for 72 h, after which samples were air dried at room temperature for 24 h. Polymer type was determined by visual inspection of resin codes and ATR FTIR spectroscopy. ATR FTIR measurements were performed on a Nicolet 8700A spectrometer (diamond ATR) with 64 scans, 4000–400 cm ⁻ ¹, 4 cm ⁻ ¹ resolution. Spectra were matched against reference spectra in the OpenSpecy database (https://openanalysis.org/openspecy/Spectra). The five most prevalent polymers were polyethylene (PE), polypropylene (PP), polystyrene (PS), Polyethersulfone (PES) and polyethylene terephthalate (PET). Each item was ground to a homogenate using a pestle and mortar, stainless steel scissors, and a screw driven grinder, then sieved through a 2 mm stainless steel mesh. The resulting powder was stored in glass vials.

Extraction and digestion

To extract exchangeable metals from the polymer surface and associated biofilm, we used the first step of a modified BCR sequential extraction protocol [34] with 0.11 M acetic acid -. This is a new approach to measuring the available (not residual) concentration of elements, which was first performed in a previous study to investigate the concentration of exchangeable elements bound to polymers [6]. Thus, we followed the protocol of the previous study to ensure that the results were comparable. Initially, 20 ml of 0.11 M acetic acid (pH ≈ 3) was added to each sample tube. The tubes were then shaken for 16 h at room temperature on a double-head shaker at 30 rpm. Following shaking, the samples were centrifuged at 400 rpm for 20 min. The resulting supernatant was carefully decanted into 60 ml Teflon centrifuge tubes, ensuring no plastic material was transferred. The remaining solid residue was rinsed with 20 mL of deionized water for 15 minutes, and the rinses were discarded.

Quality assurance

Quality assurance measures included the use of 3 types of blanks to monitor potential contamination during analysis. Procedural blank, encompassing all reagents and containers, were processed without the introduction of plastic materials. Sieve blank was prepared by rinsing a clean 2 mm stainless steel sieve and treating it in the same manner as the samples. Polymer blank, utilizing a clean polymer, were also processed identically. To assess the accuracy of the extraction protocol, the agricultural soil certified reference material (CRM) NCS ZC71009 (China National Analysis Center) was digested in triplicate.

Instrumental analysis

Elemental analysis was performed on 25 fractionated composite samples (13 PE, 4 PP, 3 PS, 4 PES, and 1 PET), 13 duplicates, and three control samples (processed identically but without plastic material). Elemental analysis, including Group 1 and 2, transition elements, and REEs, was performed using inductively coupled plasma-mass spectrometer (ICP-MS) on a Thermo Scientific iCAP 7400 Duo. Argon served as the plasma generator gas (flow rate 12 L min⁻¹) and nebulization system gas (flow rate 0.5 L min⁻¹). External standards (0.01 to 5 mg L⁻¹) were prepared by diluting a Merck multi-standard solution (HC87632955) in 2% HNO₃. Procedural blanks, processed with each sample batch, showed low and consistent values. The Method Detection Limit (MDL), as provided by the analytical laboratory and derived from reagent blanks, ranged from 0.1 μg L ⁻ ¹ to 1 μg L ⁻ ¹ for REEs and 1 μg L ⁻ ¹ to 100 μg L ⁻ ¹ for other elements. The corresponding Method Quantification Limit (MQL), calculated as 3.3 times the MDL [35], ranged from 0.33 μg L ⁻ ¹ to 3.3 μg L ⁻ ¹ for REEs and 3.3 μg L ⁻ ¹ to 330 μg L ⁻ ¹ for other elements. These were converted to mass-normalized units for direct comparison with sample data (reported in mg kg^-1, except for Li, Cd, Sb, and REEs, which are reported in μg kg^-1, Table 1), and all sample concentrations were blank-subtracted and well above the MQL. The accuracy of the extraction and analysis was verified using a certified reference soil (e.g., NIST 2711a), a justified surrogate for the challenging environmental matrices associated with weathered plastics, with recoveries ranging from ~70% for Cu and Pb to >90% for other elements. Repeatability, expressed as relative standard deviation, was better than 10% for all elements.

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Table 1. Detection limits (MDL; µg L^-1) of elements, normalized to plastic weight and solution volume (mg kg^-1) expect for Li, Cd, Sb, and REEs (µg kg^-1).

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Data handling and statistics

Statistical analyses were performed using Excel 365 and SPSS 27. The Shapiro-Wilk test was used to assess normality. Depending on the distribution and sample sizes, Kruskal-Wallis tests were conducted, followed by post-hoc pairwise comparisons using the Dwass-Steel-Critchlow-Fligner method. The False Discovery Rate (FDR) was controlled for all multiple comparisons, and results are reported with adjusted q-values, along with the number of samples used for each test. Correlation analyses included robust measures (Spearman) with 95% confidence intervals where possible. For groups with n = 1, no inferential statistics were performed; results are presented descriptively.

Results

Element concentrations overview

Elemental analysis of plastic samples revealed varying abundance and distribution patterns. The abundance of elements decreased in the order: Ca (875.96 ± 474.17 mg kg^-1)> Na (175.43 mg kg^-1) > S (167.32 ± 73.75 mg kg^-1)> Mg (162.53 ± 109.12 mg kg^-1)> Mn (40.96 ± 39.36 mg kg^-1) > K (40.01 ± 24.22 mg kg^-1)> Si (30.64 ± 18.45 mg kg^-1) > P (26.97 ± 21.87 mg kg^-1)> Al (14.55 ± 6.93 mg kg^-1)> Sr (11.88 ± 7.94 mg kg^-1)> Ba (6.02 ± 3.79 mg kg^-1)> Pb (1.47 ± 1.67 mg kg^-1)> Cu (1.15 ± 0.68 mg kg^-1)> Cr (0.9 ± 0.95 mg kg^-1)> Ni (0.44 ± 0.15 mg kg^-1)> As (0.3 ± 0.13 mg kg^-1)> Rb (0.19 ± 0.09 mg kg^-1)> Co (0.14 ± 0.09 mg kg^-1)> Ag (0.11 ± 0.13 mg kg^-1)> Ce (95.16 ± 24.22 µg kg^-1)> Cd (79.61 ± 21.17 µg kg^-1)> Li (76.27 ± 29.52 µg kg^-1) > Y (61.46 ± 16.03 µg kg^-1)> La (55.24 ± 12.41 µg kg^-1)> Nd (44.74 ± 21.72 µg kg^-1)> Sb (29.32 ± 12.55 µg kg^-1)> Sm (30.81 ± 1.45 µg kg^-1)> Gd (19.35 ± 2.9 µg kg^-1)> Dy (7.62 ± 2.19 µg kg^-1)> Lu (2.70 ± 0.19 µg kg^-1)> Eu (4.09 ± 0.22 µg kg^-1). In groups one and two, all alkali and alkaline earth elements were detected in 100% of samples except for Li (12%). Among intermediate elements, Ag, Co, and Sb were detected in 96%, 84%, and 76% of samples, respectively, while Cd and Ni were found in 68%, Cr in 24%, and As in only 8%. All other intermediate elements were present in 100% of the samples. For REEs, Nd was present in 96% of the samples, Y and Ce in 72%, La and Dy in 68%, Gd in 56%, Eu in 28%, Sm in 25%, and Lu in 12%.

Kruskal-Wallis tests revealed significant differences in adsorbed concentrations among polymer types for Dy, La, Y, Na, Cu, K, P, S, and Sr (S1 Table, p < 0.05). Post-hoc pairwise comparisons using the Dwass-Steel-Critchlow-Fligner method, with FDR control, indicated the most significant difference prior to q-value adjustment was between PES-PE PS-PE and PS-PP (p < 0.05). However, after FDR correction, only Cu and P exhibited significant differences between PP and PS (q < 0.05, rank difference = 1), while Na and S showed the largest difference between PES and PE (q < 0.05, rank difference = 1). K, Sr, Y, La, and Dy showed no significant differences between any polymer pairs after FDR control (all q > 0.05), warranting cautious interpretation.

The highest mean abundances for all group one and two elements, including Li (105.78 ± 60.82 µg kg^-1), Na (369.83 ± 313.97 mg kg^-1), K (78.05 ± 69.88 mg kg), Ca (1630.50 ± 1886.78 mg kg^-1), Mg (333.60 ± 303.16 mg kg^-1), Sr (24.26 ± 24.26 mg kg^-1) and Ba (11.15 ± 13.01 mg kg^-1), were found in PE, except for Rb which was highest in PS (0.3 ± 0.06 mg kg^-1) (Fig 1). For intermediate elements, PE exhibited the highest average abundance of Al (25.63 ± 18.68 mg kg^-1), Co (0.27 ± 0.30 mg kg^-1), Mn (115.77 ± 244.93 mg kg^-1), Ni (0.62 ± 0.33 mg kg^-1), S (258.80 ± 66.15 mg kg^-1), and Si (61.74 ± 48.69 mg kg^-1). PP contained the highest average concentrations of Cr (2.25 ± 2.14 mg kg^-1) and Pb (4.80 ± 7.12 mg kg^-1). PS showed the highest levels of Ag (0.16 ± 0.15 mg kg^-1), As (0.43 mg kg^-1), Cu (2.33 ± 1.27 mg kg^-1), Fe (33.07 ± 20.96 mg kg^-1), Zn (31.44 ± 16.38 mg kg^-1), and P (64.62 ± 30.07 mg kg^-1). Cd was highest in PES (104.8 ± 6.59 µg kg^-1), while Sb was highest in PET (40.1 µg kg^-1 from one sample) (Fig 1). Regarding REEs, PE had the highest mean concentrations of Ce (113.14 ± 60.21 µg kg^-1), Dy (9.89 ± 5.45 µg kg^-1), La (68.46 ± 37.19 µg kg^-1), Nd (79.73 ± 47.39 µg kg^-1) and Lu (2.72 ± 0.03 µg kg^-1). PP exhibited the highest mean concentrations of Gd (23.19 ± 4.77 µg kg^-1), Y (76.92 ± 18.53 µg kg^-1) and Sm and Eu from one sample (32.26 and 4.30 µg kg^-1) (Fig 2). Outliers (very high concentrations) were observed for all elemental groups in PE.

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Fig 1. Box plots summarize intermediate elements concentrations in PE (green), PP (blue), PS (yellow), PES (purple), and PET (black), displaying median, mean (×), interquartile range, minimum, maximum, and outliers.

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Fig 2. Box plots summarize rare earth element (REEs) concentrations in PE (green), PP (blue), PS (yellow), PES (purple), and PET (black), displaying median, mean (×), interquartile range, minimum, maximum, and outliers.

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Correlation analysis

Spearman correlation analysis identified significant pairwise relationships among elements with >50% abundance adsorbed onto plastic polymers (S2 Table). Following False Discovery Rate (FDR) correction (q < 0.01, dark green; q < 0.05, light green), distinct geochemical groups emerged, with correlation precision quantified by 95% confidence intervals. Correlations that lost significance after FDR correction (p < 0.05, q < 0.1) are highlighted in yellow in Fig 3.

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Fig 3. The correlation matrix of element concentrations highlights significant pairwise relationships (abundance > 50%).

Significance levels: q < 0.01, dark green; q < 0.05, light green; q < 0.1, yellow; negative correlations, red.

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A very strong and precisely-estimated positive correlation was observed within a group of alkali and alkaline earth metals. Key pairs, such as Mg–Sr (ρ = 0.974, 95% CI [0.939, 0.989]) and Na–Mg (ρ = 0.958, 95% CI [0.905, 0.982]), demonstrate that the true relationship is not only strong but also reliably estimated to be near the upper limit of the correlation scale. This group was further characterized by its strong positive correlations with the crustal elements Si and Al (e.g., Na–Si ρ = 0.806, 95% CI [0.595, 0.913]).

REEs, including La, Ce, Nd, Gd, Dy, and Y, formed an exceptionally cohesive and reliably-defined cluster. They exhibited near-perfect positive correlations among themselves, as seen in pairs like Ce–La (ρ = 0.971, 95% CI [0.916, 0.990]) and Gd–Y (ρ = 0.973, 95% CI [0.905, 0.992]), indicating a single, well-mixed source.

Among the trace metals, Cu and Zn showed a very strong positive correlation (ρ = 0.797, 95% CI [0.578, 0.909]). While this indicates a robust relationship, the wider confidence interval compared to the REE or crustal groups suggests a greater degree of uncertainty in the exact strength of this association. Furthermore, these elements were significantly correlated with the crustal elements Al and Si (e.g., Al–Zn ρ = 0.813, 95% CI [0.608, 0.916]).

In contrast, Sb demonstrated a significant negative correlation with Mn (ρ = −0.619, 95% CI [−0.842, −0.216]). The fact that the entire confidence interval is below zero and covers a large negative range reinforces the certainty of this inverse relationship. Ag showed weak to moderate negative correlations with Ce and Nd (ρ = −0.507 and −0.555, respectively); however, the associated uncertainty was considerable, with the CI for Ag-Ce including values very close to zero (95% CI [−0.800, −0.020]). Elements such as S and Pb showed few significant correlations with the major geochemical groups, and the relationships that were detected often had wide confidence intervals, indicating uncertain and potentially weak associations.

Comparison with previous studies

The concentrations of elements associated with plastics in this study were compared with findings from previous research (Table 2). Using the same acetic acid digestion method, a study conducted in Lublin, Poland [6], showed generally lower average concentrations of most elements compared to the Lithuanian samples, with the exception of Cd. Cd concentrations were approximately five times higher in the Polish study, although Cd was detected in a larger number of samples in Lithuania (16) compared to Poland (4). Ni concentrations were comparable between the two locations. Unlike the Polish study [6], which sampled both natural and industrial areas, this study focused solely on the Curonian Lagoon. Higher toxic element concentrations than those reported in the Polish study suggest potential contamination of the Lagoon.

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Table 2. Comparison of the concentrations of the studied elements with other previous studies.

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When comparing our results with studies employing nitric and hydrochloric acid digestion methods in laboratory conditions [36] and studies of natural environments [15,37,29,38], several trends emerged. Given the lack of research on elemental adsorption to plastics in wetland environments, coastal environments were considered the most relevant natural analogue. According to overall abundance, our concentrations are broadly in the same order of magnitude as coastal studies, but direct quantitative comparisons are limited by extraction schemes. Even with weaker acid digestion, Cd, Cu, Co, Cr, Zn, Mn, and Pb concentrations surpassed those of previous studies, an increase not seen for Ba, Ca, or Fe. This suggests that enclosed wetlands may be more vulnerable to toxic metal contamination than coastlines.

Discussion

Polymer properties and environmental controls on elemental adsorption

This study supports existing research indicating that plastic debris in aquatic environments primarily accumulates elements through surface adsorption from the surrounding environment, rather than through intrinsic properties [6,31,39]. The adsorbed environmentally derived elements, once released, can become bioavailable, potentially posing ecological and human health risks. The rate of this surface adsorption is influenced by both the physicochemical properties of the plastic itself and the environmental conditions and geochemical behavior of the elements in question [2,30].

PE was identified as the dominant polymer in this study, aligning with findings from a review by Dalvand and Hamidian [7] and echoing its widespread presence in wetland environments, typically followed by PP and PS. This abundance is often attributed to PE extensive use in the packaging industry and its role as a primary raw plastic material [40].

While this study did not find statistically significant differences (q < 0.05) in adsorbed element concentrations based on polymer type for all elements after FDR correction, notable trends emerged. PE exhibited the highest mean concentrations and the most outliers, suggesting a potentially greater overall affinity for element adsorption. Conversely, PS and PP, despite showing high adsorption levels in a previous study [6], displayed more consistent element adsorption behavior in this dataset, indicated by their smaller interquartile ranges. These findings highlight the complex interplay between polymeric structure, crystallinity, glass transition temperature (Tg), and adsorption. The classification of plastics as glassy (e.g., PES, PS, PET) or rubbery (e.g., PE, PP) based on Tg is crucial. Rubbery plastics, known for their larger free volumes, tend to exhibit higher metal adsorption capacities compared to dense, internally nanoporous glassy polymers [41], a trend that aligns with our observations and previous studies [30,42,43]. The pairwise post hoc test in “Element concentrations overview” Section, while limited in statistical power, indicated that the most prominent concentration differences tended to occur between polymers from these different groups (e.g., PES-PE and PS-PP), supporting this general trend.

Although pristine PE, PP, and PS are non-polar and hydrophobic, intrinsically resisting ion adsorption, the situation changes under environmental conditions. While PES and PET possess inherently polar and hydrophilic surfaces with active binding sites (COO and OH) for elements, our results, consistent with Abbasi et al. [6], suggest that the intrinsic surface charge of the pristine polymer may have a limited impact on element adsorption under ambient conditions, where factors like porosity and, crucially, environmental weathering likely play a larger role.

Given that the exact history of the plastic fragments collected in this study was unknown, the influence of environmental weathering becomes critical. Weathering processes, such as oxidation and chelation, create negative charges on polymer surfaces, enhancing adsorption capacity [32]. This is supported by Wang et al. [44], who demonstrated that aged polymers adsorbed more heavy metals than pristine polymers, likely due to increased surface area and oxygen-containing groups resulting from UV exposure. Moreover, the presence of organic matter, such as biofilms, attached to plastic pieces, exerts a strong control on element uptake [45,46].

The pH of the aqueous system further complicates adsorption dynamics. pH influences plastic surface charge [47], with acidic conditions promoting protonation and a positive charge, while neutral to alkaline conditions induce a negative charge, thus affecting electrostatic interactions with elements. This aligns with observations from Jian et al. [30] and Holmes et al. [48], who reported increased adsorption of Cu, Cd, and Pb onto plastic polymers with increasing pH. The seasonal pH fluctuations in the Curonian Lagoon, influenced by nutrient loads and biological activity [49,50], underscore the importance of considering such environmental factors.

From a geochemical perspective, the charge-to-radius ratio of ions determines their mobility [51], influencing their adsorption potential and distribution. Elements with high ratios (e.g., Na, K, Ca, Mg, Sr, Ba) exhibit low mobility, while those with low ratios (e.g., Ce, Dy, Gd, La, Nd) have high [51]. Transition elements display intermediate mobility, sensitive to environmental conditions, as reflected in our correlation patterns (Fig 4). Ionic strength significantly impacts metal desorption from plastics by influencing competitive adsorption [29,52,53]. Jian et al. [30] observed that increasing potassium concentration initially increased and then decreased metal adsorption from a K+ solution. The strong positive correlations among intermediate elements (P, Si, Al, Cu, Mn, Ni, Fe, Zn, Fig 3) suggest that the presence of alkali ions may influence their co-adsorption. Elements like Ag, Sb, Cd, and S exhibit weak or negative correlations, indicating distinct reactivity, ion exchange capacity, and partitioning [54]. S, despite its abundance, showed no strong correlation, likely due to its high electronegativity favoring specific adsorption by polar polymers or biofilm components.

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Fig 4. Al-to-La ratio in co-analyzed samples.

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Pollution sources and acknowledging uncertainties

The origin of elemental pollution in the Curonian Lagoon is of particular importance due to its specific location. The toxic elements Cd, Pb, and Ni showed moderate correlations with each other in this study but not with major geochemical groups. These elements have previously been associated with a high pollution load index in the Curonian Lagoon [27], which could be an indication of localized anthropogenic inputs near the Klaipėda Port leading to toxic element pollution and increased plastic adsorption (in line with the findings in “Comparison with previous studies” Section). However, the unknown and potentially varied sampling locations for our plastic debris limit our ability to definitively link these elements to a specific point source.

Among the trace metals, the strong correlation between Cu and Zn (ρ = 0.797) is a classic indication of non-exhaust emissions from traffic (such as brake and tire wear) [55]. Their significant correlations with crustal elements Al and Si further suggest their presence in polluted and suspended road dust [31]. In contrast, Sb showed a significant negative correlation with Mn (ρ = −0.619), highlighting a unique anthropogenic source (e.g., brake wear) that is isolated from the crustal manganese source [56,57]. Elements such as Ag showed weak negative correlations with REEs, indicating a distinct and potentially more isolated contamination pathway [58].

To further investigate geochemical provenance, we used the Al/La ratio, an established indicator for differentiating petroleum-related (Ratios of 0.012 and 0.004 for petroleum origin and 0.00056 and 0.000021 for natural origin in the study of Johnson et al. [59] and the study of Abbasi et al. [31], respectively). In our study (Fig 4), this ratio was greater than 0.003 for more than 40% of the samples, a value more closely related to an oil-related origin than a natural one. It is important to note, however, that these ratios were measured on plastics, which are a selective sink, and not on background environmental matrices (e.g., water, sediment). The lack of such background data introduces uncertainty, as we cannot directly compare the plastic-bound ratios to the ambient pool. Notwithstanding these uncertainties, the Al/La ratios leaning towards an oil signature are consistent with concerns about oil hydrocarbons (THCs) pollution in the Curonian Lagoon and the Baltic Sea, especially near the Klaipėda Strait due to maritime traffic and industrial activities [60,61].

REEs, classified as light or heavy, are emerging contaminants due to their industrial use [11,62]. They are found in consumer and environmental plastics, potentially through debris and dust contamination [11,63]. REE uptake can occur at functional sites like COOH, with light and heavy REEs following different complexation processes influenced by pH and competing ions [62]. The observed abundance of Ce, Y, La, and Nd is consistent with previous findings [11], suggesting widespread REE environmental presence. Ce and La, abundant in the upper continental crust [64], are common REEs reported in environmental studies [11,65] from sources like petroleum refineries and vehicle emissions [66–68]. Y is used in fluorescent powders and high-temperature alloys [69].

In spite of limitations including the absence of background samples like water and sediment (particularly for REEs), the lack of comparable data for bioavailable element adsorption in the initial modified BCR phase, the sample size, and the unidentified point sources, this research offers a valuable contribution. It represents a progressive step in employing REEs to trace the origin of pollutants adsorbed onto polymers, establishing a connection between elemental geochemistry and its relationship to plastic polymer adsorption. Furthermore, it paves the way for exploring the broader potential of these elements in environmental remediation efforts.

Conclusion

In conclusion, this study highlights the intricate interplay of factors governing element absorption from the environment. The influence of co-existing ions, environmental conditions, and adsorbent surface characteristics underscores the complexity of this process. This necessitates further investigation into element adsorption on plastic debris within natural ecosystems, with particular emphasis on wetland environments given their susceptibility to contamination as enclosed systems. To facilitate robust comparisons of pollution levels across diverse ecosystems, future research should prioritize the adoption of standardized methodologies. Furthermore, the study emphasizes the potential of REEs analysis, when coupled with refined analytical techniques to minimize uncertainties, to more accurately trace pollution origins in environmental studies.

Supporting information

S1 Table. Kruskal-Wallis tests and Post-hoc pairwise comparisons using the Dwass-Steel-Critchlow-Fligner method, with FDR control.

https://doi.org/10.1371/journal.pone.0340582.s001

(DOCX)

S2 Table. Spearman correlation analysis identified significant pairwise relationships among elements with >50% abundance adsorbed onto plastic polymers.

https://doi.org/10.1371/journal.pone.0340582.s002

(DOCX)

S1 Fig. Graphical abstract.

https://doi.org/10.1371/journal.pone.0340582.s003

(JPG)

Acknowledgments

We extend our gratitude to Klaipeda University, CNRS and Shiraz University for their logistical and scientific support.

References

1. Nayanathara Thathsarani Pilapitiya PGC, Ratnayake AS. The world of plastic waste: a review. Cleaner Materials. 2024;11:100220.
- View Article
- Google Scholar
2. Abbasi S. Prevalence and physicochemical characteristics of microplastics in the sediment and water of Hashilan Wetland, a national heritage in NW Iran. Environ Technol Innov. 2021;23:101782.
- View Article
- Google Scholar
3. Razeghi N, Hamidian AH, Abbasi S, Mirzajani A. Distribution, flux, and risk assessment of microplastics at the Anzali Wetland, Iran, and its tributaries. Environ Sci Pollution Res. 2024;31(42):54815–31.
- View Article
- Google Scholar
4. Soares J, Miguel I, Venâncio C, Lopes I, Oliveira M. Public views on plastic pollution: Knowledge, perceived impacts, and pro-environmental behaviours. J Hazard Mater. 2021;412:125227. pmid:33951864
- View Article
- PubMed/NCBI
- Google Scholar
5. Suaria G, Avio CG, Mineo A, Lattin GL, Magaldi MG, Belmonte G, et al. The mediterranean plastic soup: synthetic polymers in Mediterranean surface waters. Sci Rep. 2016;6:37551. pmid:27876837
- View Article
- PubMed/NCBI
- Google Scholar
6. Abbasi S, Turner A, Jędruchniewicz K, Różyło K, Oleszczuk P. Exchangeable versus residual metals in naturally aged plastic litter. Environ Sci Pollut Res Int. 2024;31(16):24197–206. pmid:38438643
- View Article
- PubMed/NCBI
- Google Scholar
7. Dalvand M, Hamidian AH. Occurrence and distribution of microplastics in wetlands. Sci Total Environ. 2023;862:160740. pmid:36496018
- View Article
- PubMed/NCBI
- Google Scholar
8. Dzihninafira H, Hamdan AM, Razi F. Microplastic Removal in Krueng Aceh River Water Using Ultrafiltration Membrane from Polyethersulfone Polymer (PES). Ind J Chem Anal. 2023;6(2):151–63.
- View Article
- Google Scholar
9. Khalid N, Aqeel M, Noman A, Khan SM, Akhter N. Interactions and effects of microplastics with heavy metals in aquatic and terrestrial environments. Environ Pollut. 2021;290:118104. pmid:34500399
- View Article
- PubMed/NCBI
- Google Scholar
10. Guzzonato A, Puype F, Harrad SJ. Evidence of bad recycling practices: BFRs in children’s toys and food-contact articles. Environ Sci Process Impacts. 2017;19(7):956–63. pmid:28636053
- View Article
- PubMed/NCBI
- Google Scholar
11. Turner A, Scott JW, Green LA. Rare earth elements in plastics. Sci Total Environ. 2021;774:145405. pmid:33607436
- View Article
- PubMed/NCBI
- Google Scholar
12. Wang X, Zhang C, Li S, Wang C, Wang H, Cui Y. Ecological risk, health risk assessment, and pollution source analysis of Xinli Lake wetland based on triangular fuzzy number. Environ Sci Pollut Res Int. 2021;28(18):22334–47. pmid:33417134
- View Article
- PubMed/NCBI
- Google Scholar
13. Torres FG, Dioses-Salinas DC, Pizarro-Ortega CI, De-la-Torre GE. Sorption of chemical contaminants on degradable and non-degradable microplastics: Recent progress and research trends. Sci Total Environ. 2021;757:143875. pmid:33310573
- View Article
- PubMed/NCBI
- Google Scholar
14. Hirai H, Takada H, Ogata Y, Yamashita R, Mizukawa K, Saha M, et al. Organic micropollutants in marine plastics debris from the open ocean and remote and urban beaches. Mar Pollut Bull. 2011;62(8):1683–92. pmid:21719036
- View Article
- PubMed/NCBI
- Google Scholar
15. Holmes LA, Turner A, Thompson RC. Adsorption of trace metals to plastic resin pellets in the marine environment. Environ Pollut. 2012;160(1):42–8. pmid:22035924
- View Article
- PubMed/NCBI
- Google Scholar
16. Mato Y, Isobe T, Takada H, Kanehiro H, Ohtake C, Kaminuma T. Plastic resin pellets as a transport medium for toxic chemicals in the marine environment. Environ Sci Technol. 2001;35(2):318–24. pmid:11347604
- View Article
- PubMed/NCBI
- Google Scholar
17. Gao N, Yang L, Lu X, Duan Z, Zhu L, Feng J. A review of interactions of microplastics and typical pollutants from toxicokinetics and toxicodynamics perspective. J Hazard Mater. 2022;432:128736. pmid:35339832
- View Article
- PubMed/NCBI
- Google Scholar
18. Rochman CM, Hoh E, Kurobe T, Teh SJ. Ingested plastic transfers hazardous chemicals to fish and induces hepatic stress. Sci Rep. 2013;3:3263. pmid:24263561
- View Article
- PubMed/NCBI
- Google Scholar
19. Abbasi S, et al. Fluxes, residence times, and the budget of microplastics in the Curonian Lagoon. Environmental Pollution. 2025;:126289.
- View Article
- Google Scholar
20. Hashemi N, Keshavarzi B, Amini-Birami F, Biester H, Zafarani GG, Zarei M. Potentially toxic elements in sediment and water of Amirkalayeh Wetland: Impacted by intensive rice farming. Environ Monit Assess. 2025;197(7):742. pmid:40483282
- View Article
- PubMed/NCBI
- Google Scholar
21. Kurt MA, Yalçın S, Güler C, Güven O, Yıldırım Ü. Pollution Source and Soil Quality Assessments of Heavily Contaminated Soils by Selected Potentially Toxic Elements in a Human-Degraded Wetland Area. Sustainability. 2024;16(13):5477.
- View Article
- Google Scholar
22. Tafti ND. Characterization of sulfur chemistry in Louisiana coastal wetland soils using X-ray absorption fine structure (XAFS) spectroscopy. Louisiana State University and Agricultural & Mechanical College. 2017.
23. Kasamesiri P, Panchan R, Thaimuangphol W. Spatial–temporal distribution and ecological risk assessment of microplastic pollution of inland fishing ground in the ubolratana reservoir, Thailand. Water. 2023;15(2):330.
- View Article
- Google Scholar
24. Vaikutienė G, Skipitytė R, Mažeika J, Martma T, Garbaras A, Barisevičiūtė R, et al. Environmental changes induced by human activities in the Northern Curonian Lagoon (Eastern Baltic): diatoms and stable isotope data; pp. 93–108. EJES. 2017;66(2):93–108.
- View Article
- Google Scholar
25. Bocherikova IY, Lobchuk OI, Chubarenko IP. Comparative analysis of contamination with microplastic particles of ice in the Curonian Lagoon (Baltic Sea) and Novik Bay (Sea of Japan), in All-Russian Conference of Young Scientists “COMPLEX INVESTIGATION OF THE WORLD OCEAN. Springer; 2023;376–80.
26. Emelyanov EM, Gulbinskas S, Suzdalev S. Biogenic components and trace elements in the sediments of river mouths and accumulation areas of the Curonian Lagoon (south-eastern Baltic Sea). Baltica. 2015;28(2).
- View Article
- Google Scholar
27. Jokšas K, Galkus A, Stakėnienė R. Heavy metal contamination of the Curonian Lagoon bottom sediments (Lithuanian waters area). Baltica. 2016;29(2).
- View Article
- Google Scholar
28. Krek A, Krechik V, Danchenkov A, Krek E. Pollution of the sediments of the coastal zone of the Sambia Peninsula and the Curonian Spit (Southeastern Baltic Sea). PeerJ. 2018;6:e4770. pmid:29785348
- View Article
- PubMed/NCBI
- Google Scholar
29. Lee A, Mondon J, Merenda A, Dumée LF, Callahan DL. Surface adsorption of metallic species onto microplastics with long-term exposure to the natural marine environment. Sci Total Environ. 2021;780:146613. pmid:34030302
- View Article
- PubMed/NCBI
- Google Scholar
30. Jian M, Niu J, Li W, Huang Y, Yu H, Lai Z, et al. How do microplastics adsorb metals? A preliminary study under simulated wetland conditions. Chemosphere. 2022;309(Pt 1):136547. pmid:36167202
- View Article
- PubMed/NCBI
- Google Scholar
31. Abbasi S, Keshavarzi B, Moore F, Hopke PK, Kelly FJ, Dominguez AO. Elemental and magnetic analyses, source identification, and oxidative potential of airborne, passive, and street dust particles in Asaluyeh County, Iran. Sci Total Environ. 2020;707:136132.
- View Article
- Google Scholar
32. Chen P-W, Hsiao M-N, Xiao L-W, Liu Z-S. Adsorption behavior of heavy metals onto microplastics derived from conventional and biodegradable commercial plastic products. Sci Total Environ. 2024;951:175537. pmid:39151633
- View Article
- PubMed/NCBI
- Google Scholar
33. Huang 34 X, Zemlyanov DY, Diaz-Amaya S, Salehi M, Stanciu L, Whelton AJ. Competitive heavy metal adsorption onto new and aged polyethylene under various drinking water conditions. J Hazard Mater. 2020;385:121585.
- View Article
- Google Scholar
34. Rauret G, López-Sánchez JF, Sahuquillo A, Rubio R, Davidson C, Ure A, et al. Improvement of the BCR three step sequential extraction procedure prior to the certification of new sediment and soil reference materials. J Environ Monit. 1999;1(1):57–61. pmid:11529080
- View Article
- PubMed/NCBI
- Google Scholar
35. U. S. EPA. EPA 821-R-16-006 definition and procedure for the determination of the method detection limit, revision 2. Washington, DC: U. S. EPA. 2016.
36. Turner A, Holmes LA. Adsorption of trace metals by microplastic pellets in fresh water. Environ Chemistry. 2015;12(5):600–10.
- View Article
- Google Scholar
37. Souza LA, Santos ACSS, Leão JM, Schaeppi OC, Hatje V. Occurrence and contents of trace metals and rare earth elements on plastic pellets. Mar Pollut Bull. 2022;185(Pt A):114261. pmid:36347193
- View Article
- PubMed/NCBI
- Google Scholar
38. Carbery M, MacFarlane GR, O’Connor W, Afrose S, Taylor H, Palanisami T. Baseline analysis of metal(loid)s on microplastics collected from the Australian shoreline using citizen science. Mar Pollut Bull. 2020;152:110914. pmid:32479287
- View Article
- PubMed/NCBI
- Google Scholar
39. Abbasi S, Keshavarzi B, Moore F, Shojaei N, Sorooshian A, Soltani N, et al. Geochemistry and environmental effects of potentially toxic elements, polycyclic aromatic hydrocarbons and microplastics in coastal sediments of the Persian Gulf. Environ Earth Sci. 2019;78(15).
- View Article
- Google Scholar
40. Amrutha K, Warrier AK. The first report on the source-to-sink characterization of microplastic pollution from a riverine environment in tropical India. Sci Total Environ. 2020;739:140377. pmid:32758976
- View Article
- PubMed/NCBI
- Google Scholar
41. Free CM, Jensen OP, Mason SA, Eriksen M, Williamson NJ, Boldgiv B. High-levels of microplastic pollution in a large, remote, mountain lake. Mar Pollut Bull. 2014;85(1):156–63. pmid:24973278
- View Article
- PubMed/NCBI
- Google Scholar
42. Pascall MA, Zabik ME, Zabik MJ, Hernandez RJ. Uptake of polychlorinated biphenyls (PCBs) from an aqueous medium by polyethylene, polyvinyl chloride, and polystyrene films. J Agric Food Chem. 2005;53(1):164–9. pmid:15631524
- View Article
- PubMed/NCBI
- Google Scholar
43. Teuten EL, Saquing JM, Knappe DRU, Barlaz MA, Jonsson S, Björn A, et al. Transport and release of chemicals from plastics to the environment and to wildlife. Philos Trans R Soc Lond B Biol Sci. 2009;364(1526):2027–45. pmid:19528054
- View Article
- PubMed/NCBI
- Google Scholar
44. Wang Q, Zhang Y, Wangjin X, Wang Y, Meng G, Chen Y. The adsorption behavior of metals in aqueous solution by microplastics effected by UV radiation. J Environ Sci (China). 2020;87:272–80. pmid:31791500
- View Article
- PubMed/NCBI
- Google Scholar
45. Ganesan S, Ruendee T, Kimura SY, Chawengkijwanich C, Janjaroen D. Effect of biofilm formation on different types of plastic shopping bags: Structural and physicochemical properties. Environ Res. 2022;206:112542. pmid:34929185
- View Article
- PubMed/NCBI
- Google Scholar
46. Zhao E, Xiong X, Li X, Hu H, Wu C. Effect of Biofilm Forming on the Migration of Di(2-ethylhexyl)phthalate from PVC Plastics. Environ Sci Technol. 2024;58(14):6326–34. pmid:38551364
- View Article
- PubMed/NCBI
- Google Scholar
47. Li X, Qu J, Yin H. Electrolytic alloy‐type anodes for metal‐ion batteries. Rare Metals. 2020;40(2):329–52.
- View Article
- Google Scholar
48. Holmes LA, Turner A, Thompson RC. Interactions between trace metals and plastic production pellets under estuarine conditions. Mar Chem. 2014;167:25–32.
- View Article
- Google Scholar
49. Omstedt A, Edman M, Claremar B, Frodin P, Gustafsson E, Humborg C, et al. Future changes in the Baltic Sea acid–base (pH) and oxygen balances. Tellus B: Chemical and Physical Meteorol. 2012;64(1):19586.
- View Article
- Google Scholar
50. Cotovicz LC, Cahill B, Sabbaghzadeh B, Lencina‐Avila JM, Rehder G. Increase in marginal sea alkalinity may impact air–sea carbon dioxide exchange and buffer acidification. Limnol Oceanogr. 2024;69(10):2332–47.
- View Article
- Google Scholar
51. Rollinson HR, Rollinson H, Pease V. Using geochemical data: to understand geological processes. Cambridge University Press. 2021.
52. Seidensticker S, Zarfl C, Cirpka OA, Fellenberg G, Grathwohl P. Shift in mass transfer of wastewater contaminants from microplastics in the presence of dissolved substances. Environ Sci Technol. 2017;51(21):12254–63. pmid:28965391
- View Article
- PubMed/NCBI
- Google Scholar
53. Cabaniss SE. Forward modeling of metal complexation by NOM: II. prediction of binding site properties. Environ Sci Technol. 2011;45(8):3202–9. pmid:21087041
- View Article
- PubMed/NCBI
- Google Scholar
54. Purwiyanto AIS, et al. Concentration and adsorption of Pb and Cu in microplastics: case study in aquatic environment. Mar Pollut Bull. 2020;158:111380. pmid:32568083
- View Article
- PubMed/NCBI
- Google Scholar
55. Zhang M, Li J, Yin H, Wang X, Qin Y, Yang Z, et al. Pilot analysis of tire tread characteristics and associated tire-wear particles in vehicles produced across distinct time periods. Sci Total Environ. 2024;932:172760. pmid:38670369
- View Article
- PubMed/NCBI
- Google Scholar
56. Varrica D, Bardelli F, Dongarra G, Tamburo E. ‘Speciation of Sb in airborne particulate matter, vehicle brake linings, and brake pad wear residues’. Atmos Environ. 2013;64:18–24.
- View Article
- Google Scholar
57. Lopez B, Wang X, Chen L-WA, Ma T, Mendez-Jimenez D, Cobb LC, et al. Metal contents and size distributions of brake and tire wear particles dispersed in the near-road environment. Sci Total Environ. 2023;883:163561. pmid:37088393
- View Article
- PubMed/NCBI
- Google Scholar
58. Vural A. Investigation of the relationship between rare earth elements, trace elements, and major oxides in soil geochemistry. Environ Monit Assess. 2020;192(2):124. pmid:31960198
- View Article
- PubMed/NCBI
- Google Scholar
59. Johnson DL, Davis BL, Dzubay TG, Hasan H, Crutcher ER, Courtney WJ, et al. Chemical and physical analyses of Houston aerosol for interlaboratory comparison of source apportionment procedures. Atmospheric Environment (1967). 1984;18(8):1539–53.
- View Article
- Google Scholar
60. Garnaga G, Stukova Z. Contamination of the south-eastern Baltic Sea and the Curonian Lagoon with oil products. In: 2008 IEEE/OES US/EU-Baltic International Symposium. IEEE; 2008. 1–8.
61. Stakėnienė R, Jokšas K, Galkus A, Raudonytė-Svirbutavičienė E. Polycyclic aromatic hydrocarbons in surface sediments from the Curonian Lagoon and the Nemunas River Delta (Lithuania, Baltic Sea): distribution, origin, and suggestions for the monitoring program. Environ Monit Assess. 2019;191(4):212. pmid:30852690
- View Article
- PubMed/NCBI
- Google Scholar
62. Blancho F, Davranche M, Marsac R, Léon A, Dia A, Grassl B, et al. Metal-binding processes on nanoplastics: rare earth elements as probes. Environ Sci: Nano. 2022;9(6):2094–103.
- View Article
- Google Scholar
63. Marra A, Cesaro A, Rene ER, Belgiorno V, Lens PNL. Bioleaching of metals from WEEE shredding dust. J Environ Manage. 2018;210:180–90. pmid:29353112
- View Article
- PubMed/NCBI
- Google Scholar
64. Taylor SR, McLennan SM. The continental crust: its composition and evolution. 1985.
65. Guan W, Zhang J, Liu Q. Quantitative evaluation of anthropogenic sources and health risks of rare earth elements in airborne particulate matter. Sci Total Environ. 2024;945:173960. pmid:38897472
- View Article
- PubMed/NCBI
- Google Scholar
66. Akinlua A, Torto N, Ajayi TR. Determination of rare earth elements in Niger Delta crude oils by inductively coupled plasma-mass spectrometry. Fuel. 2008;87(8–9):1469–77.
- View Article
- Google Scholar
67. Kulkarni P, Chellam S, Fraser MP. Lanthanum and lanthanides in atmospheric fine particles and their apportionment to refinery and petrochemical operations in Houston, TX. Atmos Environ. 2006;40(3):508–20.
- View Article
- Google Scholar
68. Yan Y, et al. Characteristics and provenances of rare earth elements in the atmospheric particles of a coastal city with large-scale optoelectronic industries. Atmos Environ. 2019;214:116836.
- View Article
- Google Scholar
69. Puype F, Samsonek J, Vilímková V, Kopečková Š, Ratiborská A, Knoop J, et al. Towards a generic procedure for the detection of relevant contaminants from waste electric and electronic equipment (WEEE) in plastic food-contact materials: a review and selection of key parameters. Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2017;34(10):1767–83. pmid:28521663
- View Article
- PubMed/NCBI
- Google Scholar

[ref1] 1. Nayanathara Thathsarani Pilapitiya PGC, Ratnayake AS. The world of plastic waste: a review. Cleaner Materials. 2024;11:100220.
View Article
Google Scholar

[2] View Article

[3] Google Scholar

[ref2] 2. Abbasi S. Prevalence and physicochemical characteristics of microplastics in the sediment and water of Hashilan Wetland, a national heritage in NW Iran. Environ Technol Innov. 2021;23:101782.
View Article
Google Scholar

[5] View Article

[6] Google Scholar

[ref3] 3. Razeghi N, Hamidian AH, Abbasi S, Mirzajani A. Distribution, flux, and risk assessment of microplastics at the Anzali Wetland, Iran, and its tributaries. Environ Sci Pollution Res. 2024;31(42):54815–31.
View Article
Google Scholar

[8] View Article

[9] Google Scholar

[ref4] 4. Soares J, Miguel I, Venâncio C, Lopes I, Oliveira M. Public views on plastic pollution: Knowledge, perceived impacts, and pro-environmental behaviours. J Hazard Mater. 2021;412:125227. pmid:33951864
View Article
PubMed/NCBI
Google Scholar

[11] View Article

[12] PubMed/NCBI

[13] Google Scholar

[ref5] 5. Suaria G, Avio CG, Mineo A, Lattin GL, Magaldi MG, Belmonte G, et al. The mediterranean plastic soup: synthetic polymers in Mediterranean surface waters. Sci Rep. 2016;6:37551. pmid:27876837
View Article
PubMed/NCBI
Google Scholar

[15] View Article

[16] PubMed/NCBI

[17] Google Scholar

[ref6] 6. Abbasi S, Turner A, Jędruchniewicz K, Różyło K, Oleszczuk P. Exchangeable versus residual metals in naturally aged plastic litter. Environ Sci Pollut Res Int. 2024;31(16):24197–206. pmid:38438643
View Article
PubMed/NCBI
Google Scholar

[19] View Article

[20] PubMed/NCBI

[21] Google Scholar

[ref7] 7. Dalvand M, Hamidian AH. Occurrence and distribution of microplastics in wetlands. Sci Total Environ. 2023;862:160740. pmid:36496018
View Article
PubMed/NCBI
Google Scholar

[23] View Article

[24] PubMed/NCBI

[25] Google Scholar

[ref8] 8. Dzihninafira H, Hamdan AM, Razi F. Microplastic Removal in Krueng Aceh River Water Using Ultrafiltration Membrane from Polyethersulfone Polymer (PES). Ind J Chem Anal. 2023;6(2):151–63.
View Article
Google Scholar

[27] View Article

[28] Google Scholar

[ref9] 9. Khalid N, Aqeel M, Noman A, Khan SM, Akhter N. Interactions and effects of microplastics with heavy metals in aquatic and terrestrial environments. Environ Pollut. 2021;290:118104. pmid:34500399
View Article
PubMed/NCBI
Google Scholar

[30] View Article

[31] PubMed/NCBI

[32] Google Scholar

[ref10] 10. Guzzonato A, Puype F, Harrad SJ. Evidence of bad recycling practices: BFRs in children’s toys and food-contact articles. Environ Sci Process Impacts. 2017;19(7):956–63. pmid:28636053
View Article
PubMed/NCBI
Google Scholar

[34] View Article

[35] PubMed/NCBI

[36] Google Scholar

[ref11] 11. Turner A, Scott JW, Green LA. Rare earth elements in plastics. Sci Total Environ. 2021;774:145405. pmid:33607436
View Article
PubMed/NCBI
Google Scholar

[38] View Article

[39] PubMed/NCBI

[40] Google Scholar

[ref12] 12. Wang X, Zhang C, Li S, Wang C, Wang H, Cui Y. Ecological risk, health risk assessment, and pollution source analysis of Xinli Lake wetland based on triangular fuzzy number. Environ Sci Pollut Res Int. 2021;28(18):22334–47. pmid:33417134
View Article
PubMed/NCBI
Google Scholar

[42] View Article

[43] PubMed/NCBI

[44] Google Scholar

[ref13] 13. Torres FG, Dioses-Salinas DC, Pizarro-Ortega CI, De-la-Torre GE. Sorption of chemical contaminants on degradable and non-degradable microplastics: Recent progress and research trends. Sci Total Environ. 2021;757:143875. pmid:33310573
View Article
PubMed/NCBI
Google Scholar

[46] View Article

[47] PubMed/NCBI

[48] Google Scholar

[ref14] 14. Hirai H, Takada H, Ogata Y, Yamashita R, Mizukawa K, Saha M, et al. Organic micropollutants in marine plastics debris from the open ocean and remote and urban beaches. Mar Pollut Bull. 2011;62(8):1683–92. pmid:21719036
View Article
PubMed/NCBI
Google Scholar

[50] View Article

[51] PubMed/NCBI

[52] Google Scholar

[ref15] 15. Holmes LA, Turner A, Thompson RC. Adsorption of trace metals to plastic resin pellets in the marine environment. Environ Pollut. 2012;160(1):42–8. pmid:22035924
View Article
PubMed/NCBI
Google Scholar

[54] View Article

[55] PubMed/NCBI

[56] Google Scholar

[ref16] 16. Mato Y, Isobe T, Takada H, Kanehiro H, Ohtake C, Kaminuma T. Plastic resin pellets as a transport medium for toxic chemicals in the marine environment. Environ Sci Technol. 2001;35(2):318–24. pmid:11347604
View Article
PubMed/NCBI
Google Scholar

[58] View Article

[59] PubMed/NCBI

[60] Google Scholar

[ref17] 17. Gao N, Yang L, Lu X, Duan Z, Zhu L, Feng J. A review of interactions of microplastics and typical pollutants from toxicokinetics and toxicodynamics perspective. J Hazard Mater. 2022;432:128736. pmid:35339832
View Article
PubMed/NCBI
Google Scholar

[62] View Article

[63] PubMed/NCBI

[64] Google Scholar

[ref18] 18. Rochman CM, Hoh E, Kurobe T, Teh SJ. Ingested plastic transfers hazardous chemicals to fish and induces hepatic stress. Sci Rep. 2013;3:3263. pmid:24263561
View Article
PubMed/NCBI
Google Scholar

[66] View Article

[67] PubMed/NCBI

[68] Google Scholar

[ref19] 19. Abbasi S, et al. Fluxes, residence times, and the budget of microplastics in the Curonian Lagoon. Environmental Pollution. 2025;:126289.
View Article
Google Scholar

[70] View Article

[71] Google Scholar

[ref20] 20. Hashemi N, Keshavarzi B, Amini-Birami F, Biester H, Zafarani GG, Zarei M. Potentially toxic elements in sediment and water of Amirkalayeh Wetland: Impacted by intensive rice farming. Environ Monit Assess. 2025;197(7):742. pmid:40483282
View Article
PubMed/NCBI
Google Scholar

[73] View Article

[74] PubMed/NCBI

[75] Google Scholar

[ref21] 21. Kurt MA, Yalçın S, Güler C, Güven O, Yıldırım Ü. Pollution Source and Soil Quality Assessments of Heavily Contaminated Soils by Selected Potentially Toxic Elements in a Human-Degraded Wetland Area. Sustainability. 2024;16(13):5477.
View Article
Google Scholar

[77] View Article

[78] Google Scholar

[ref22] 22. Tafti ND. Characterization of sulfur chemistry in Louisiana coastal wetland soils using X-ray absorption fine structure (XAFS) spectroscopy. Louisiana State University and Agricultural & Mechanical College. 2017.

[ref23] 23. Kasamesiri P, Panchan R, Thaimuangphol W. Spatial–temporal distribution and ecological risk assessment of microplastic pollution of inland fishing ground in the ubolratana reservoir, Thailand. Water. 2023;15(2):330.
View Article
Google Scholar

[81] View Article

[82] Google Scholar

[ref24] 24. Vaikutienė G, Skipitytė R, Mažeika J, Martma T, Garbaras A, Barisevičiūtė R, et al. Environmental changes induced by human activities in the Northern Curonian Lagoon (Eastern Baltic): diatoms and stable isotope data; pp. 93–108. EJES. 2017;66(2):93–108.
View Article
Google Scholar

[84] View Article

[85] Google Scholar

[ref25] 25. Bocherikova IY, Lobchuk OI, Chubarenko IP. Comparative analysis of contamination with microplastic particles of ice in the Curonian Lagoon (Baltic Sea) and Novik Bay (Sea of Japan), in All-Russian Conference of Young Scientists “COMPLEX INVESTIGATION OF THE WORLD OCEAN. Springer; 2023;376–80.

[ref26] 26. Emelyanov EM, Gulbinskas S, Suzdalev S. Biogenic components and trace elements in the sediments of river mouths and accumulation areas of the Curonian Lagoon (south-eastern Baltic Sea). Baltica. 2015;28(2).
View Article
Google Scholar

[88] View Article

[89] Google Scholar

[ref27] 27. Jokšas K, Galkus A, Stakėnienė R. Heavy metal contamination of the Curonian Lagoon bottom sediments (Lithuanian waters area). Baltica. 2016;29(2).
View Article
Google Scholar

[91] View Article

[92] Google Scholar

[ref28] 28. Krek A, Krechik V, Danchenkov A, Krek E. Pollution of the sediments of the coastal zone of the Sambia Peninsula and the Curonian Spit (Southeastern Baltic Sea). PeerJ. 2018;6:e4770. pmid:29785348
View Article
PubMed/NCBI
Google Scholar

[94] View Article

[95] PubMed/NCBI

[96] Google Scholar

[ref29] 29. Lee A, Mondon J, Merenda A, Dumée LF, Callahan DL. Surface adsorption of metallic species onto microplastics with long-term exposure to the natural marine environment. Sci Total Environ. 2021;780:146613. pmid:34030302
View Article
PubMed/NCBI
Google Scholar

[98] View Article

[99] PubMed/NCBI

[100] Google Scholar

[ref30] 30. Jian M, Niu J, Li W, Huang Y, Yu H, Lai Z, et al. How do microplastics adsorb metals? A preliminary study under simulated wetland conditions. Chemosphere. 2022;309(Pt 1):136547. pmid:36167202
View Article
PubMed/NCBI
Google Scholar

[102] View Article

[103] PubMed/NCBI

[104] Google Scholar

[ref31] 31. Abbasi S, Keshavarzi B, Moore F, Hopke PK, Kelly FJ, Dominguez AO. Elemental and magnetic analyses, source identification, and oxidative potential of airborne, passive, and street dust particles in Asaluyeh County, Iran. Sci Total Environ. 2020;707:136132.
View Article
Google Scholar

[106] View Article

[107] Google Scholar

[ref32] 32. Chen P-W, Hsiao M-N, Xiao L-W, Liu Z-S. Adsorption behavior of heavy metals onto microplastics derived from conventional and biodegradable commercial plastic products. Sci Total Environ. 2024;951:175537. pmid:39151633
View Article
PubMed/NCBI
Google Scholar

[109] View Article

[110] PubMed/NCBI

[111] Google Scholar

[ref33] 33. Huang 34 X, Zemlyanov DY, Diaz-Amaya S, Salehi M, Stanciu L, Whelton AJ. Competitive heavy metal adsorption onto new and aged polyethylene under various drinking water conditions. J Hazard Mater. 2020;385:121585.
View Article
Google Scholar

[113] View Article

[114] Google Scholar

[ref34] 34. Rauret G, López-Sánchez JF, Sahuquillo A, Rubio R, Davidson C, Ure A, et al. Improvement of the BCR three step sequential extraction procedure prior to the certification of new sediment and soil reference materials. J Environ Monit. 1999;1(1):57–61. pmid:11529080
View Article
PubMed/NCBI
Google Scholar

[116] View Article

[117] PubMed/NCBI

[118] Google Scholar

[ref35] 35. U. S. EPA. EPA 821-R-16-006 definition and procedure for the determination of the method detection limit, revision 2. Washington, DC: U. S. EPA. 2016.

[ref36] 36. Turner A, Holmes LA. Adsorption of trace metals by microplastic pellets in fresh water. Environ Chemistry. 2015;12(5):600–10.
View Article
Google Scholar

[121] View Article

[122] Google Scholar

[ref37] 37. Souza LA, Santos ACSS, Leão JM, Schaeppi OC, Hatje V. Occurrence and contents of trace metals and rare earth elements on plastic pellets. Mar Pollut Bull. 2022;185(Pt A):114261. pmid:36347193
View Article
PubMed/NCBI
Google Scholar

[124] View Article

[125] PubMed/NCBI

[126] Google Scholar

[ref38] 38. Carbery M, MacFarlane GR, O’Connor W, Afrose S, Taylor H, Palanisami T. Baseline analysis of metal(loid)s on microplastics collected from the Australian shoreline using citizen science. Mar Pollut Bull. 2020;152:110914. pmid:32479287
View Article
PubMed/NCBI
Google Scholar

[128] View Article

[129] PubMed/NCBI

[130] Google Scholar

[ref39] 39. Abbasi S, Keshavarzi B, Moore F, Shojaei N, Sorooshian A, Soltani N, et al. Geochemistry and environmental effects of potentially toxic elements, polycyclic aromatic hydrocarbons and microplastics in coastal sediments of the Persian Gulf. Environ Earth Sci. 2019;78(15).
View Article
Google Scholar

[132] View Article

[133] Google Scholar

[ref40] 40. Amrutha K, Warrier AK. The first report on the source-to-sink characterization of microplastic pollution from a riverine environment in tropical India. Sci Total Environ. 2020;739:140377. pmid:32758976
View Article
PubMed/NCBI
Google Scholar

[135] View Article

[136] PubMed/NCBI

[137] Google Scholar

[ref41] 41. Free CM, Jensen OP, Mason SA, Eriksen M, Williamson NJ, Boldgiv B. High-levels of microplastic pollution in a large, remote, mountain lake. Mar Pollut Bull. 2014;85(1):156–63. pmid:24973278
View Article
PubMed/NCBI
Google Scholar

[139] View Article

[140] PubMed/NCBI

[141] Google Scholar

[ref42] 42. Pascall MA, Zabik ME, Zabik MJ, Hernandez RJ. Uptake of polychlorinated biphenyls (PCBs) from an aqueous medium by polyethylene, polyvinyl chloride, and polystyrene films. J Agric Food Chem. 2005;53(1):164–9. pmid:15631524
View Article
PubMed/NCBI
Google Scholar

[143] View Article

[144] PubMed/NCBI

[145] Google Scholar

[ref43] 43. Teuten EL, Saquing JM, Knappe DRU, Barlaz MA, Jonsson S, Björn A, et al. Transport and release of chemicals from plastics to the environment and to wildlife. Philos Trans R Soc Lond B Biol Sci. 2009;364(1526):2027–45. pmid:19528054
View Article
PubMed/NCBI
Google Scholar

[147] View Article

[148] PubMed/NCBI

[149] Google Scholar

[ref44] 44. Wang Q, Zhang Y, Wangjin X, Wang Y, Meng G, Chen Y. The adsorption behavior of metals in aqueous solution by microplastics effected by UV radiation. J Environ Sci (China). 2020;87:272–80. pmid:31791500
View Article
PubMed/NCBI
Google Scholar

[151] View Article

[152] PubMed/NCBI

[153] Google Scholar

[ref45] 45. Ganesan S, Ruendee T, Kimura SY, Chawengkijwanich C, Janjaroen D. Effect of biofilm formation on different types of plastic shopping bags: Structural and physicochemical properties. Environ Res. 2022;206:112542. pmid:34929185
View Article
PubMed/NCBI
Google Scholar

[155] View Article

[156] PubMed/NCBI

[157] Google Scholar

[ref46] 46. Zhao E, Xiong X, Li X, Hu H, Wu C. Effect of Biofilm Forming on the Migration of Di(2-ethylhexyl)phthalate from PVC Plastics. Environ Sci Technol. 2024;58(14):6326–34. pmid:38551364
View Article
PubMed/NCBI
Google Scholar

[159] View Article

[160] PubMed/NCBI

[161] Google Scholar

[ref47] 47. Li X, Qu J, Yin H. Electrolytic alloy‐type anodes for metal‐ion batteries. Rare Metals. 2020;40(2):329–52.
View Article
Google Scholar

[163] View Article

[164] Google Scholar

[ref48] 48. Holmes LA, Turner A, Thompson RC. Interactions between trace metals and plastic production pellets under estuarine conditions. Mar Chem. 2014;167:25–32.
View Article
Google Scholar

[166] View Article

[167] Google Scholar

[ref49] 49. Omstedt A, Edman M, Claremar B, Frodin P, Gustafsson E, Humborg C, et al. Future changes in the Baltic Sea acid–base (pH) and oxygen balances. Tellus B: Chemical and Physical Meteorol. 2012;64(1):19586.
View Article
Google Scholar

[169] View Article

[170] Google Scholar

[ref50] 50. Cotovicz LC, Cahill B, Sabbaghzadeh B, Lencina‐Avila JM, Rehder G. Increase in marginal sea alkalinity may impact air–sea carbon dioxide exchange and buffer acidification. Limnol Oceanogr. 2024;69(10):2332–47.
View Article
Google Scholar

[172] View Article

[173] Google Scholar

[ref51] 51. Rollinson HR, Rollinson H, Pease V. Using geochemical data: to understand geological processes. Cambridge University Press. 2021.

[ref52] 52. Seidensticker S, Zarfl C, Cirpka OA, Fellenberg G, Grathwohl P. Shift in mass transfer of wastewater contaminants from microplastics in the presence of dissolved substances. Environ Sci Technol. 2017;51(21):12254–63. pmid:28965391
View Article
PubMed/NCBI
Google Scholar

[176] View Article

[177] PubMed/NCBI

[178] Google Scholar

[ref53] 53. Cabaniss SE. Forward modeling of metal complexation by NOM: II. prediction of binding site properties. Environ Sci Technol. 2011;45(8):3202–9. pmid:21087041
View Article
PubMed/NCBI
Google Scholar

[180] View Article

[181] PubMed/NCBI

[182] Google Scholar

[ref54] 54. Purwiyanto AIS, et al. Concentration and adsorption of Pb and Cu in microplastics: case study in aquatic environment. Mar Pollut Bull. 2020;158:111380. pmid:32568083
View Article
PubMed/NCBI
Google Scholar

[184] View Article

[185] PubMed/NCBI

[186] Google Scholar

[ref55] 55. Zhang M, Li J, Yin H, Wang X, Qin Y, Yang Z, et al. Pilot analysis of tire tread characteristics and associated tire-wear particles in vehicles produced across distinct time periods. Sci Total Environ. 2024;932:172760. pmid:38670369
View Article
PubMed/NCBI
Google Scholar

[188] View Article

[189] PubMed/NCBI

[190] Google Scholar

[ref56] 56. Varrica D, Bardelli F, Dongarra G, Tamburo E. ‘Speciation of Sb in airborne particulate matter, vehicle brake linings, and brake pad wear residues’. Atmos Environ. 2013;64:18–24.
View Article
Google Scholar

[192] View Article

[193] Google Scholar

[ref57] 57. Lopez B, Wang X, Chen L-WA, Ma T, Mendez-Jimenez D, Cobb LC, et al. Metal contents and size distributions of brake and tire wear particles dispersed in the near-road environment. Sci Total Environ. 2023;883:163561. pmid:37088393
View Article
PubMed/NCBI
Google Scholar

[195] View Article

[196] PubMed/NCBI

[197] Google Scholar

[ref58] 58. Vural A. Investigation of the relationship between rare earth elements, trace elements, and major oxides in soil geochemistry. Environ Monit Assess. 2020;192(2):124. pmid:31960198
View Article
PubMed/NCBI
Google Scholar

[199] View Article

[200] PubMed/NCBI

[201] Google Scholar

[ref59] 59. Johnson DL, Davis BL, Dzubay TG, Hasan H, Crutcher ER, Courtney WJ, et al. Chemical and physical analyses of Houston aerosol for interlaboratory comparison of source apportionment procedures. Atmospheric Environment (1967). 1984;18(8):1539–53.
View Article
Google Scholar

[203] View Article

[204] Google Scholar

[ref60] 60. Garnaga G, Stukova Z. Contamination of the south-eastern Baltic Sea and the Curonian Lagoon with oil products. In: 2008 IEEE/OES US/EU-Baltic International Symposium. IEEE; 2008. 1–8.

[ref61] 61. Stakėnienė R, Jokšas K, Galkus A, Raudonytė-Svirbutavičienė E. Polycyclic aromatic hydrocarbons in surface sediments from the Curonian Lagoon and the Nemunas River Delta (Lithuania, Baltic Sea): distribution, origin, and suggestions for the monitoring program. Environ Monit Assess. 2019;191(4):212. pmid:30852690
View Article
PubMed/NCBI
Google Scholar

[207] View Article

[208] PubMed/NCBI

[209] Google Scholar

[ref62] 62. Blancho F, Davranche M, Marsac R, Léon A, Dia A, Grassl B, et al. Metal-binding processes on nanoplastics: rare earth elements as probes. Environ Sci: Nano. 2022;9(6):2094–103.
View Article
Google Scholar

[211] View Article

[212] Google Scholar

[ref63] 63. Marra A, Cesaro A, Rene ER, Belgiorno V, Lens PNL. Bioleaching of metals from WEEE shredding dust. J Environ Manage. 2018;210:180–90. pmid:29353112
View Article
PubMed/NCBI
Google Scholar

[214] View Article

[215] PubMed/NCBI

[216] Google Scholar

[ref64] 64. Taylor SR, McLennan SM. The continental crust: its composition and evolution. 1985.

[ref65] 65. Guan W, Zhang J, Liu Q. Quantitative evaluation of anthropogenic sources and health risks of rare earth elements in airborne particulate matter. Sci Total Environ. 2024;945:173960. pmid:38897472
View Article
PubMed/NCBI
Google Scholar

[219] View Article

[220] PubMed/NCBI

[221] Google Scholar

[ref66] 66. Akinlua A, Torto N, Ajayi TR. Determination of rare earth elements in Niger Delta crude oils by inductively coupled plasma-mass spectrometry. Fuel. 2008;87(8–9):1469–77.
View Article
Google Scholar

[223] View Article

[224] Google Scholar

[ref67] 67. Kulkarni P, Chellam S, Fraser MP. Lanthanum and lanthanides in atmospheric fine particles and their apportionment to refinery and petrochemical operations in Houston, TX. Atmos Environ. 2006;40(3):508–20.
View Article
Google Scholar

[226] View Article

[227] Google Scholar

[ref68] 68. Yan Y, et al. Characteristics and provenances of rare earth elements in the atmospheric particles of a coastal city with large-scale optoelectronic industries. Atmos Environ. 2019;214:116836.
View Article
Google Scholar

[229] View Article

[230] Google Scholar

[ref69] 69. Puype F, Samsonek J, Vilímková V, Kopečková Š, Ratiborská A, Knoop J, et al. Towards a generic procedure for the detection of relevant contaminants from waste electric and electronic equipment (WEEE) in plastic food-contact materials: a review and selection of key parameters. Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2017;34(10):1767–83. pmid:28521663
View Article
PubMed/NCBI
Google Scholar

[232] View Article

[233] PubMed/NCBI

[234] Google Scholar

Geochemical signatures in plastic debris from the Curonian Lagoon, Lithuania

Geochemical signatures in plastic debris from the Curonian Lagoon, Lithuania

Correction

Figures

Abstract

Introduction

Materials and methods

Sample collection and polymer identification

Extraction and digestion

Quality assurance

Instrumental analysis

Data handling and statistics

Results

Element concentrations overview

Correlation analysis

Comparison with previous studies

Discussion

Polymer properties and environmental controls on elemental adsorption

Pollution sources and acknowledging uncertainties

Conclusion

Supporting information

S1 Table. Kruskal-Wallis tests and Post-hoc pairwise comparisons using the Dwass-Steel-Critchlow-Fligner method, with FDR control.

S2 Table. Spearman correlation analysis identified significant pairwise relationships among elements with >50% abundance adsorbed onto plastic polymers.

S1 Fig. Graphical abstract.

Acknowledgments

References