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The development of agricultural technologies has intensified the use of plastic in this sector. Products of plastic degradation, such as microplastics (MPs), potentially threaten living organisms, biodiversity and agricultural ecosystem functioning. Thus, biodegradable plastic materials have been introduced to agriculture. However, the effects of biodegradable plastic substitutes on soil ecosystems are even less known than those of traditional ones. Here, we studied the effects of environmentally relevant concentrations of MPs prepared from a biodegradable plastic (a starch-polybutylene adipate terephthalate blend, PBAT-BD-MPs) on the growth and defense mechanisms of lettuce (Lactuca sativa) in CLIMECS system (CLImatic Manipulation of ECosystem Samples). PBAT-BD-MPs in the highest concentrations negatively affected some traits of growth, i.e., dry weight percentage, specific leaf area, and both C and N contents. We observed more profound changes in plant physiology and biochemistry, as PBAT-BD-MPs decreased chlorophyll content and triggered a concerted response of plant defense mechanisms against oxidative stress. In conclusion, exposure to PBAT-BD-MPs induced plant oxidative stress and activated plant defense mechanisms, leading to oxidative homeostasis that sustained plant growth and functioning. Our study highlights the need for in-depth understanding of the effect of bioplastics on plants., Competing Interests: Declaration of competing interest No conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Degradation and fragmentation of mulching films represents an increasing source of microplastics (MPs, plastic particles 1 μm to 5 mm in size) to agricultural soils. MPs have been shown to affect many soil invertebrates, including springtails. However, these studies typically use test materials representing less environmentally relevant particle types, such as pristine uniform MPs, which do not represent the large range of particle sizes and morphologies found in the field. This study aimed at providing insight into the adverse effects of MPs originating from agricultural mulching films, by using artificially aged MPs derived from both biodegradable (starch-polybutadiene adipate terephthalate (PBAT)) blend, as well as conventional (linear low-density polyethylene (LLDPE)) plastic polymers. The soil dwelling springtail Folsomia candida was exposed to these MPs for five generations in order to elucidate population effects due to possible reproduction toxicity, endocrine disruption, mutagenesis or developmental toxicity. F. candida were exposed to 0, 0.0016, 0.008, 0.04, 0.2, 1, 2, 3, 4 and 5 % (w/w dry soil) MPs in Lufa 2.2 soil, which includes concentrations within the range of environmental relevance. Juveniles produced at each concentration were transferred to the next generation, with the parental, F2 and F4 generations being exposed for four weeks and F1 and F3 generations for five weeks. No concentration-dependent effects on F. candida survival or reproduction were observed in exposures to either of the MPs, in any of the generations. These results suggest that the particular MPs used in this study, derived from mulching films used on agricultural soils, may not be potent toxicants to F. candida, even after long-term exposure and at elevated concentrations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Microplastics (MPs) are one of the most widespread contaminants worldwide, yet their risks for freshwater ecosystems have seldom been investigated. In this study, we performed a large monitoring campaign to assess the presence and risks of MPs in Amazonian freshwater ecosystems. We investigated MP pollution in 40 samples collected along 1500 km in the Brazilian Amazon, including the Amazon River, three major tributaries, and several streams next to the most important urban areas. MPs in the 55-5000 µm size range were characterized (size, shape, color) by microscopy and identified (polymer composition) by infrared spectroscopy. Ecotoxicological risks were assessed using chronic Species Sensitivity Distributions for effects triggered by food dilution and tissue translocation using data alignment methods that correct for polydispersity of environmental MPs and bioaccessibility. This study shows that MPs are ubiquitous contaminants in Amazonian freshwater ecosystems, with measured concentrations (55-5000 µm) ranging between 5 and 152 MPs/m 3 in the Amazon River and its main tributaries, and between 23 and 74,550 MPs/m 3 in urban streams. The calculated Hazardous Concentration for the 5% of species (HC 5 ) derived from the SSDs for the entire MP range (1-5000 µm) were 1.6 × 10 7 MPs/m 3 (95% CI: 1.2 × 10 6 - 4.0 × 10 8 ) for food dilution, and 1.8 × 10 7 MPs/m 3 (95% CI: 1.5 × 10 6 - 4.3 × 10 8 ) for translocation. Rescaled exposure concentrations (1-5000 µm) in the Amazon River and tributaries ranged between 6.0 × 10 3 and 1.8 × 10 5 MPs/m 3 , and were significantly lower than the calculated HC 5 values. Rescaled concentrations in urban streams ranged between 1.7 × 10 5 and 5.7 × 10 8 MPs/m 3 , and exceeded both calculated HC 5 values in 20% of the locations. This study shows that ecological impacts by MP contamination are not likely to happen in the Amazon River and its major tributaries. However, risks for freshwater organisms may be expected in near densely populated areas, such as the cities of Manaus or Belem, which have limited wastewater treatment facilities., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Sewage sludge used as agricultural fertilizer has been identified as an important source of microplastics (MPs) to the environment. However, the fate of MPs added to agricultural soils is largely unknown. This study investigated the fate of MPs in agricultural soils amended with sewage sludge and the role of surface water runoff as a mechanism driving their transfer to aquatic ecosystems. This was assessed using three experimental plots located in a semi-arid area of Central Spain, which were planted with barley. The experimental plots received the following treatments: (1) control or no sludge application; (2) historical sludge application, five years prior to the experiment; and (3) sludge application at the beginning of the experiment. MPs were analyzed in surface water runoff and in different soil layers to investigate transport and infiltration for one year. The sewage sludge used in our experiment contained 5972-7771 MPs/kg dw. Based on this, we estimated that about 16,000 MPs were added to the agricultural plot amended with sludge. As expected, the sludge application significantly increased the MP concentration in soils. The control plot contained low MP concentrations (31-120 MPs kg -1 dw), potentially originating from atmospheric deposition. The plot treated five years prior to the experiment contained 226-412 and 177-235 MPs kg -1 dw at the start and end of the experiment, respectively; while the recently treated plot contained 182-231 and 138-288 MPs kg -1 dw. Our study shows that MP concentrations remain relatively constant in agricultural soils and that the MP infiltration capacity is very low. Surface water runoff had a negligible influence on the export of MPs from agricultural soils, mobilizing only 0.2-0.4% of the MPs added with sludge. We conclude that, in semi-arid regions, agricultural soils can be considered as long-term accumulators of MPs., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

A significant proportion of marine plastic debris and microplastics is assumed to be derived from river systems. In order to effectively manage plastic contamination of the marine environment, an accurate quantification of riverine flux of land-based plastics and microplastics is imperative. Rivers not only represent pathways to the ocean, but are also complex ecosystems that support many life processes and ecosystem services. Yet riverine microplastics research is still in its infancy, and many uncertainties still remain. Major barriers exist in two aspects. First, nonharmonized sampling methodologies make it problematic for compiling data across studies to better estimate riverine fluxes of microplastics globally; Second, the significant spatiotemporal variation of microplastics in rivers which was affected by the river characteristics, MPs properties, etc. also have important influence on the estimation of riverine MPs fluxes. In this study, we made a comprehensive review from the above two aspects based on published peer-reviewed studies and provide recommendations and suggestions for a reliable monitoring strategy of riverine MPs, which is beneficial to the further establish sampling methods for rivers in different geographical locations. Besides, methods for achieving a high level of comparability across studies in different geographical contexts are highlighted. Riverine microplastic flux monitoring is another important part of this manuscript. The influential factors and calculation methods of microplastic flux in rivers are also discussed in this paper.

Given the increasing attention on the occurrence of microplastics in the environment, and the potential environmental threats they pose, there is a need for researchers to move quickly from basic understanding to applied science that supports decision makers in finding feasible mitigation measures and solutions. At the same time, they must provide sufficient, accurate and clear information to the media, public and other relevant groups (e.g., NGOs). Key requirements include systematic and coordinated research efforts to enable evidence-based decision making and to develop efficient policy measures on all scales (national, regional and global). To achieve this, collaboration between key actors is essential and should include researchers from multiple disciplines, policymakers, authorities, civil and industry organizations, and the public. This further requires clear and informative communication processes, and open and continuous dialogues between all actors. Cross-discipline dialogues between researchers should focus on scientific quality and harmonization, defining and accurately communicating the state of knowledge, and prioritization of topics that are critical for both research and policy, with the common goal to establish and update action plans for holistic benefit. In Norway, cross-sectoral collaboration has been fundamental in supporting the national strategy to address plastic pollution. Researchers, stakeholders and the environmental authorities have come together to exchange knowledge, identify knowledge gaps, and set targeted and feasible measures to tackle one of the most challenging aspects of plastic pollution: microplastic. In this article, we present a Norwegian perspective on the state of knowledge on microplastic research efforts. Norway's involvement in international efforts to combat plastic pollution aims at serving as an example of how key actors can collaborate synergistically to share knowledge, address shortcomings, and outline ways forward to address environmental challenges., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Microplastics (MPs) are considered to be ubiquitous contaminants in freshwater ecosystems, yet their sources and pathways at the river catchment scale need to be better determined. This study assessed MP (55-5000 µm) pollution in a Mediterranean river catchment (central Spain) and aimed to identify the importance of wastewater as an environmental pathway. We sampled treated and untreated wastewaters, and raw and digested sludge from five WWTPs during two seasons. River water and sediments were sampled at three locations with different anthropogenic influences during three seasons. On average, 93% (47-99%) of MPs were retained by WWTPs. Concentrations in river water and sediment ranged between 1 and 227 MPs/m 3 and 0-2630 MPs/kg dw, respectively. Concentrations strongly depended upon land-use, with pollution levels increasing significantly downstream of urban and industrial areas. Seasonality influenced the observed MP concentrations strongly. During high flow periods, higher water but lower sediment concentrations were observed compared to low flow periods. We estimate that 1 × 10 10 MPs are discharged into the catchment via treated and untreated wastewater annually, which constitutes up to 50% of the total MP catchment discharge. Thus, we conclude that the wastewater system represents a major environmental pathway for MPs into Mediterranean rivers with low dilution capacity., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Microplastics are a diverse category of pollutants, comprising a range of constituent polymers modified by varying quantities of additives and sorbed pollutants, and exhibiting a range of morphologies, sizes, and visual properties. This diversity, as well as their microscopic size range, presents numerous barriers to identification and enumeration. These issues are addressed with the application of physical and chemical analytical procedures; however, these present new problems associated with researcher training, facility availability and cost, especially for large-scale monitoring programs. Perhaps more importantly, the classifications and nomenclature used by individual researchers to describe microplastics remains inconsistent. In addition to reducing comparability between studies, this limits the conclusions that may be drawn regarding plastic sources and potential environmental impacts. Additionally, where particle morphology data is presented, it is often separate from information on polymer distribution. In establishing a more rigorous and standardized visual identification procedure, it is possible to improve the targeting of complex analytical techniques and improve the standards by which we monitor and record microplastic contamination. Here we present a simple and effective protocol to enable consistent visual processing of samples with an aim to contribute to a higher degree of standardization within the microplastic scientific community. This protocol will not eliminate the need for non-subjective methods to verify plastic objects, but it will standardize the criteria by which suspected plastic items are identified and reduce the costs associated with further analysis.

Reference materials (RMs) are vital tools in the validation of methods used to detect environmental pollutants. Microplastics, a relatively new environmental pollutant, require a variety of complex approaches to address their presence in environmental samples. Both interlaboratory comparison (ILC) studies and RMs are essential to support the validation of methods used in microplastic analysis. Presented here are results of quality assurance and quality control (QA/QC) performed on two types of candidate microplastic RMs: dissolvable gelatin capsules and soda tablets. These RMs have been used to support numerous international ILC studies in recent years (2019–2022). Dissolvable capsules containing polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyethylene (PE), and polystyrene (PS), in different size fractions from 50 to 1000 µm, were produced for one ILC study, obtaining relative standard deviation (RSD) from 0 to 24%. The larger size fraction allowed for manual addition of particles to the capsules, yielding 0% error and 100% recovery during QA/QC. Dissolvable capsules were replaced by soda tablets in subsequent ILC studies and recovery test exercises because they were found to be a more reliable carrier for microplastic RMs. Batches of soda tablets were produced containing different single and multiple polymer mixtures, i.e., PE, PET, PS, PVC, polypropylene (PP), and polycarbonate (PC), with RSD ranging from 8 to 21%. Lastly, soda tablets consisting of a mixture of PE, PVC, and PS (125–355 µm) were produced and used for recovery testing during pretreatment of environmental samples. These had an RSD of 9%. Results showed that soda tablets and capsules containing microplastics >50 µm could be produced with sufficient precision for internal recovery tests and external ILC studies. Further work is required to optimize this method for smaller microplastics (< 50 µm) because variation was found to be too large during QA/QC. Nevertheless, this approach represents a valuable solution addressing many of the challenges associated with validating microplastic analytical methods. [ABSTRACT FROM AUTHOR]

Microplastics have been detected in lake environments globally, including in remote regions. Agricultural and populated areas are known to congregate several inputs and release pathways for microplastic. This study investigated microplastic (50–5000 µm) contamination in five Danish freshwater lakes with catchments dominated by arable land use. The concentrations in sediments (n = 3/site) and the zebra mussel, Dreissena polymorpha (n = 30/site), were calculated and compared with catchment characteristics and environmental parameters. Microplastic concentrations in sediment were relatively low (average 0.028 ± 0.017 items/g dry weight sediment) whilst only a single microplastic was found in the mussels (average 0.067 ± 0.249 items/10 individual). Hence, no relationship between the number of observed microplastics in sediment and mussels could be identified, nor could a relationship between concentration in sediment and environmental parameters. As all lakes studied received their water from moderate to heavily anthropogenically impacted catchments, it was expected that they would be sinks for microplastic with high bioavailability. Based on the results of the present study, D. polymorpha were found to not be contaminated by microplastics in the five study lakes. Thus, our results suggest that these mussels do not interact with microplastics at low concentrations. We speculate that the results on sediment and biota could be explained by several factors related to regional differences in plastic use, species characteristics, sampling size, and the fact that finding no microplastic is not always reported in the scientific literature. Thus, the paper provides insight into the dynamics between the catchment, lake, and biota in systems with low microplastic concentration. [ABSTRACT FROM AUTHOR]

Microplastic ingestion has been shown for various organisms, but knowledge of the potential adverse effects on freshwater invertebrates remains limited. We assessed the ingestion capacity and the associated effects of polyester fibers (26–5761 µm) and car tire particles (25–75 µm) on freshwater invertebrates under acute and chronic exposure conditions. A range of microplastic concentrations was tested on Daphnia magna, Hyalella azteca, Asellus aquaticus, and Lumbriculus variegatus using water only (up to 0.15 g/L) or spiked sediment (up to 2 g/kg dry wt), depending on the habitat of the species. Daphnia magna did not ingest any fibers, but low levels of fibers were ingested by all tested benthic invertebrate species. Car tire particle ingestion rose with increasing exposure concentration for all tested invertebrates and was highest in D. magna and L. variegatus. In most cases, no statistically significant effects on mobility, survival, or reproductive output were observed after acute and chronic exposure at the tested concentrations. However, fibers affected the reproduction and survival of D. magna (no‐observed‐effect concentration [NOEC]: 0.15 mg/L) due to entanglement and limited mobility under chronic conditions. Car tire particles affected the reproduction (NOEC: 1.5 mg/L) and survival (NOEC: 0.15 mg/L) of D. magna after chronic exposure at concentrations in the same order of magnitude as modeled river water concentrations, suggesting that refined exposure and effect studies should be performed with these microplastics. Our results confirm that microplastic ingestion by freshwater invertebrates depends on particle shape and size and that ingestion quantity depends on the exposure pathway and the feeding strategy of the test organism. Environ Toxicol Chem 2022;41:1555–1567. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. [ABSTRACT FROM AUTHOR]

Soils are recipients of microplastic that can be subsequently transferred to the sea. Land sources dominate inputs to the ocean, but knowledge gaps about microplastic retention by land hinder assessments of input rates. Here we present the first empirical evaluation of a dynamic microplastic fate model operating at landscape level. This mechanistic model accounts for hydrology, soil and sediment erosion, particle characteristics and behavior. We predict microplastic concentrations in water and sediments of the Henares river (Spain) within the measurement uncertainty boundaries (error factors below 2 and 10, respectively). Microplastic export from land and discharge by river fluctuates in a non-linear manner with precipitation and runoff variability. This indicates the need of accurate dynamic descriptions of soil and stream hydrology even when modeling microplastic fate and transport in generic scenarios and at low spatio-temporal resolution. A time-averaged landscape retention efficiency was calculated showing 20–50% of the microplastics added to the catchment over a multiannual period were retained. While the analysis reveals persistent uncertainties and knowledge gaps on microplastic sources to the catchment, these results contribute to the quantitative understanding of the role of terrestrial environments in accumulating microplastics, delaying their transport to the sea. [Display omitted] • Microplastic fate model in terrestrial environment validated against empirical data. • 20–50% Microplastic retention efficiency by landscape is estimated. • Model predictions are within measurement uncertainty boundaries. • Microplastic runoff from soil is an important source to the river. • Sources of microplastic to terrestrial environment remain uncertain. [ABSTRACT FROM AUTHOR]

Between April to November of 2017, microplastics (MPs) were analysed in biosolids from two separate suppliers, and in the soils of three agricultural fields to which they were applied, in Ontario, Canada. Soils of a control site with no history of biosolid application were also examined. High MP concentrations of between 8.7 × 103 MP kg−1 and 1.4 × 104 MP kg−1 were found in biosolids samples. Lower MP concentrations observed in Provider 2 biosolids may be due to storage, settling and supernatant removal prior to applications. Annual MP additions to agricultural soils across Ontario were estimated at between 4.1 × 1011 and 1.3 × 1012 particles. All fields receiving biosolids had higher soil pre-treatment MP concentrations than the control. The field with the greatest number of previous biosolid treatments had the highest pre-treatment soil MP concentrations; suggesting some MP retention in soils between applications. Immediately following biosolids applications, two fields demonstrated significant increases in soil MP concentrations, with preferential retention of MP fibers over fragments observed, while a reduction in soil MP concentrations were observed in the third. Surprisingly, only one field demonstrated a net gain in soil MPs over the course of the study. At all three fields, >99% of MPs applied in biosolids in 2017 were unaccounted for. The study suggests that despite adhering to applicable legislation, biosolids applications at all sites likely result in high rates of MP export. This study is the first to track MP transport through soils following their application in biosolids, and contributes to filling current knowledge gaps regarding export of MPs to aquatic systems from the terrestrial environment. Unlabelled Image • Microplastic (MP) concentrations of up to 1.4 × 104 MP kg−1 were found in biosolids. • Storage of biosolids should be explored as a method for reducing biosolids' MP content. • Some MP fibers are retained in soils, while fragments are predominantly exported. • >99% of MPs applied from biosolids were likely exported to the aquatic environment. • Biosolids application legislation may need revisions to incorporate MP management. [ABSTRACT FROM AUTHOR]

Some narratives present biodegradable plastic use for soil mulching practices in agriculture as "environmentally friendly" and "sustainable" alternatives to conventional plastics. To verify these narratives, environmental research recently started focusing on their potential impact on soil health, highlighting some concerns. The paper by Degli-Innocenti criticizes this unfolding knowledge arguing that it is affected by communication hypes, alarmistic writing and a focus on exposure scenarios purposedly crafted to yield negative effects. The quest of scientists for increased impact – the paper concludes – is the driver of such behavior. As scholars devoted to the safeguarding of scientific integrity, we set to verify whether this serious claim is grounded in evidence. Through a bibliometric analysis (using number of paper reads, citations and mentions on social media to measure the impact of publications) we found that: i) the papers pointed out by Degli-Innocenti as examples of biased works do not score higher than the median of similar publications; ii) the methodology used to support the conclusion is non-scientific; and iii) the paper does not fulfil the requirements concerning disclosure of conflicts of interests. We conclude that this paper represents a non-scientific opinion, potentially biased by a conflict of interest. We ask the paper to be clearly tagged as such, after the necessary corrections on the ethic section have been made. That being said, the paper does offer some useful insights for the definition of exposure scenarios in risk assessment. We comment and elaborate on these proposed models, hoping that this can help to advance the field. • The paper main conclusion was assessed through bibliometric analysis. • No evidence that hypes in papers' titles results in high impact. • The incomplete disclosure of competing interests is reported. • Evidence of residues of biodegradable plastic films in soil is given. • The predicted environmental concentration model is critically discussed. [ABSTRACT FROM AUTHOR]

Abrasion of tire wear is one of the largest sources of microplastics to the environment. Although most tire particles settle into soils, studies on their ecotoxicological impacts on the terrestrial environment are scarce. Here, the effects of tire particles (<180 μm) on three ecologically relevant soil invertebrate species, the enchytraeid worm Enchytraeus crypticus , the springtail Folsomia candida and the woodlouse Porcellio scaber , were studied. These species were exposed to tire particles spiked in soil or in food at concentrations of 0.02%, 0.06%, 0.17%, 0.5% and 1.5% (w/w). Tire particles contained a variety of potentially harmful substances. Zinc (21 900 mg kg−1) was the dominant trace element, whilst the highest concentrations of the measured organic compounds were detected for benzothiazole (89.2 mg kg−1), pyrene (4.85 mg kg−1), chlorpyrifos (0.351 mg kg−1), HCB (0.134 mg kg−1), methoxychlor (0.116 mg kg−1) and BDE 28 (0.100 mg kg−1). At the highest test concentration in soil (1.5%), the tire particles decreased F. candida reproduction by 38% and survival by 24%, and acetylcholinesterase (AChE) activity of P. scaber by 65%, whilst the slight decrease in the reproduction of E. crypticus was not dose-dependent. In food, the highest test concentration of tire particles reduced F. candida survival by 38%. These results suggest that micro-sized tire particles can affect soil invertebrates at concentrations found at roadsides, whilst short-term impacts at concentrations found further from the roadsides are unlikely. • Negative impacts of tire particles on soil invertebrates are possible at roadsides. • Tire particles slightly decreased reproduction and survival of springtail F. candida. • Tire particles decreased AChE activity of isopod P. scaber. • No dose-dependent effects of tire particles on enchytraeid E. crypticus observed. • Tire particles contained a variety of potentially harmful substances. [ABSTRACT FROM AUTHOR]