Downward migrating microplastics in lake sediments are a tricky indicator for the onset of the Anthropocene

Integration of machine learning and meta-analysis reveals the behaviors and mechanisms of antibiotic adsorption on microplastics

Microplastics (MPs) can adsorb antibiotics (ATs) to cause combined pollution in the environment. Research on this topic has been limited to specific types of MPs and ATs, resulting in inconsistent findings, particularly for the influencing factors and adsorption mechanisms. Therefore, this study combined meta-analysis and machine learning to analyze a dataset comprising 6805 records from 123 references. The results indicated that polyamide has the highest adsorption capacity for ATs, which is primarily attributed to the formation of hydrogen bonds by its N-H groups, and MPs exhibited the strongest affinity for chlortetracycline because the CO and -Cl groups in chlortetracycline form hydrogen and halogen bonds with MPs. Moreover, the particle size, MP and AT concentrations, and pH were key factors affecting the adsorption process with notable interaction effects. Hydrogen bonding and electrostatic interaction were commonly involved in the adsorption of ATs onto MPs. Finally, an interactive graphical user interface was deployed to predict the adsorption amount, affinity constant, and maximum adsorption capacity of MPs for ATs, with results aligning well with the latest published data. This study provides crucial insights into the behavior of MPs carrying ATs, thereby facilitating accurate assessment of the combined environmental risks of them.

Microplastic distribution in large shallow lake sediments: Variations with offshore distance and implications for microbial communities

Microplastics (MPs) are ubiquitous in global ecosystems and pose potential threats to the environment and biodiversity. However, the impact of MPs on microorganisms in real environments remains unclear. Our study focuses on the composition and distribution of MPs in sediments at different offshore distances in Taihu Lake. Our results indicated that MP abundance ranged from 240 to 1120 items/kg and decreased linearly with increasing offshore distance. Fibres dominated, with an average proportion of 47.58 %, and MPs within a particle size range of 0.5-1 mm (53.88 %) had the highest content. PA and PVC were the most abundant polymer types, accounting for 55.85 % and 17.94 %, respectively. The abundance of MPs in sediments was significantly positively correlated (P < 0.01) with the abundance of Firmicutes and significantly negatively correlated with the abundance of Planctomycetota. MPs account for 0.49 % of the variation in microbial alpha diversity and 1.88 % of the variation in microbial community composition. Our study demonstrates that environmental factor and MPs significantly affect microbial diversity and species composition. In summary, our research reveals the distribution patterns of MPs in sediments at different offshore distances in Taihu Lake, confirming the potential impact of MPs on microbial communities.

Significant microplastic accumulation and burial in the intertidal sedimentary environments of the Yellow River Delta

Estuarine intertidal habitats provide a dynamic and distinctive environment for the transport of microplastics, yet their migration and accumulation in these areas remain poorly understood. Herein, the spatial distribution patterns of microplastics in the estuarine sedimentary environment of the Yellow River Delta were investigated across elevation and depth gradients. Compared to the subtidal and supratidal zones, the estuarine intertidal zone exhibited the highest microplastic abundance in sediment (1027 ± 29 items/kg). Sediment cores revealed that the highest microplastic abundance occurred at a depth of 5-10 cm. The evolution of microplastic size and morphology characteristics with sediment depth indicates vertical transport of microplastics in estuarine sediments. The strong correlations between organic matter, silt content, and microplastics abundance in estuarine sediments suggested significant impacts of tidal hydrodynamics and sediment characteristics on microplastic migration processes. Estimates indicated that microplastic burial in the deeper sediments (638.7 tons in the 5-30 cm layer) was 1.96 times greater than that in the upper layers. Distinct variations in the carbonyl index across habitats suggested that tidal-induced dynamic redox conditions in the intertidal zone promoted both biotic and abiotic aging processes of microplastics. This study provides new insights into the environmental behavior and long-term fate of microplastics in estuarine intertidal sedimentary environments.

A novel protein corona-induced aggregation-ECL strategy based on poly-l-cys/Cu NCs for detecting microplastics in water

To address the health risks posed by microplastics (MPs), this work developed a poly-l-cysteine (poly-L-cys)-based electrochemiluminescence (ECL) sensor for detecting MPs in water environments. The porous structure of poly-L-cys film can regulate the generation of copper nanoclusters (Cu NCs) in the pores, effectively limiting the migration and aggregation of nanopaticles. In addition, poly-L-cys film also acted as co-reactant promoters, promoting electron transfer and effectively enhancing ECL signal of Cu NCs. Therefore, Cu NCs in the poly-L-cys porous membrane has been used as luminescent probes. Furthermore, the poly-L-cys/Cu NC-based ECL sensor was constructed with the protein corona induced aggregation effect (PCIAE) to determine the concentration of MP. Due to the strong binding affinity of PCIAE, MP can adsorb strongly to biomolecule surfaces as a protein crown. So, the modified BSA on the poly-L-cys film was removed by MP, resulting in the ECL signal enhancement. The PCIAE-ECL sensor has been successfully applied to measure MP in lakes with excellent recovery rates (90.7-106.0 %). The PCIAE-ECL sensor provided a new analytical method for detecting MPs in water environments.

Interpretable machine learning models reveal the partnership of microplastics and perfluoroalkyl substances in sediments at a century scale

It is challenging to explore the complex interactions between perfluoroalkyl substances (PFASs) and microplastics in lake sediments. The partnership of perfluoroalkyl substances (PFASs) and microplastics in lake sediments are difficult to determine experimentally. This study utilized sediment cores from Taihu Lake to reconstruct the coexistence history and innovatively reveal the collaboration between PFASs and microplastics by using post-hoc interpretable machine learning methods. Microplastics and PFASs emerged in the 1960s and have significantly increased since the 1990s. PFASs and microplastics had the highest growth rate in the 0-10 cm range, with average growth rates of 35.96 pg/g/year and 4.40 items/year per 100 g, respectively. Extreme gradient boosting demonstrated the best simulation of PFASs and microplastics in machine learning models. Feature importance and Shapley additive explanations semi-quantitatively clarified the importance of transparent and pellet microplastics on PFASs concentrations, as well as the importance of perfluorooctane sulfonate (PFOS) and ΣPFASs on microplastics. Moisture content, redox potential, χfd, and χARM were the key influencing factors on contaminants. Partial dependence plots showed the influencing thresholds were 0.30 ng/g for ΣPFASs and 0.15 ng/g for PFOS on microplastics, and 10 items per 100 g for pellets and 12 items per 100 g for transparent plastics on PFASs. This study elucidated the interactions between two typical emerging contaminants on a century-scale through the intersection of environmental geochemistry and interpretable machine learning.

Microplastic burial potential and ecological risks in mangrove forests of the Amazon River delta

Coastal mangrove ecosystems have been shown to be important microplastic (MP) sinks. Yet, information regarding their MP sequestration capacity is scant. Here, we characterized the spatial and vertical distribution of MPs in mangrove ecosystems of the Amazon River delta and quantified, for the first time, their MP burial and potential economic value related to their surface water filtering capacity. Furthermore, we assessed the ecotoxicological risks considering differing effect mechanisms for benthic organisms (i.e., food dilution and translocation-mediated effects). Soil core samples (up to 3 m) were taken from seven locations in the northern part of the Amazon River delta and analyzed for MP contamination. MPs in the 100-5000 μm range were measured and the polymer type was characterized using Fourier Transform Infrared Spectroscopy. The collected soil samples were dated based on a radionuclide analysis, and a burial analysis was done based on the sediment mass accumulation rates and the mass concentration of MPs. The outcomes of this study show that MPs are ubiquitous contaminants in mangroves of the Amazon River delta (present in 30 out of the 35 analyzed samples). The largest MP concentration was found in the upper soil layer (0-15 cm), 138 MPs/kg dw, which has been deposited and reworked during the time of the soil core collection. However, moderate exposure levels were also found in older samples (71-138 MPs/kg dw), and in samples taken before the plastic era (≈ 1870-1930), suggesting a downward MP migration. We estimated a mean burial rate of 0.32 ± 0.17 kg of MPs km2/year, which corresponds to 0.55 ± 0.28 tons per year in the Amazon River delta. Based on the estimated burial rate, we valued the removal of MPs from surface waters by these mangroves at 0.3-1.1 million USD per year. Our study shows that the exposure levels of MPs in mangroves of the Amazon River delta are relatively low when compared to other mangrove ecosystems and ecotoxicological risks for benthic organisms are not expected given the current exposure levels.

Pollution status of microplastics in the sediments of warm monomictic Dal lake, India: Abundance, composition, and risk assessment

This report presents the first investigation of microplastic (MP) contamination in the shoreline sediments of Dal Lake, Jammu and Kashmir, India. The MP concentrations ranged from 503 to 3154 MP/kg, with a notable seasonal variation. The highest concentrations of microplastics occurred in the Spring, ranging from 467 to 3445 MP/kg. Microplastics were identified using optical microscopy, Fourier Transform Infrared spectroscopy, and thermogravimetric analysis. Polymer analysis revealed that the Gagribal basin was contaminated with polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyamide (PA), and polyethylene terephthalate (PET). In contrast, the Nigeen basin mainly comprises PE, PP, and PS. The significantly elevated Polymer Hazard Index (PHI) values, exceeding 1000 in the Gagribal basin, were attributed to the presence of PVC. Sediment quality was assessed using Pollution Load Index (PLI), Potential Ecological Risk Index (PERI), and PHI. Health risk metrics, such as estimated daily intake (EDI) and microplastic carcinogenic risks (MPCR), were also evaluated. There is a positive correlation between microplastic abundance and total organic carbon (TOC), total phosphorus (TP), and total nitrogen (TN). The Nigeen basin, characterized by a higher proportion of less hazardous polymers like PP, exhibited greater TOC levels due to enhanced microbial degradation of microplastics. Conversely, the Gagribal basin, with its higher presence of toxic polymers like PVC, had lower TOC levels, likely due to these compounds' inhibition of microbial activity. This study provides crucial insight into the spatial distribution and ecological impact of MPs in Dal Lake, setting the stage for future research on their effects on aquatic ecosystems.

Evaluating physiological responses of microalgae towards environmentally coexisting microplastics: A meta-analysis

Microplastics (MPs) are abundantly present in aquatic environments, where the phytoplankton-microalgae, are now inevitably bound to a long-term coexistence with them. While numerous studies have focused on the toxicological effects of high-concentration MPs exposure, there remains controversy over whether and how MPs affect microalgae at environmentally relevant concentrations. This study aims to draw conclusions that narrow the gap from 52 studies with varying results. Overall, MPs can inhibit growth and photosynthesis, induce oxidative damage, from which microalgae can recover after an appropriate period. Cyanobacteria exhibit greater vulnerability than chlorophyta. The relative size of MPs to algal cells potentially governs their coexistence behavior, thereby altering the mechanisms of impact. Pristine MPs may increase the production of extracellular polymeric substances (EPS) and microcystins (MCs), while aged MPs have the opposite effect. Additionally, relevant factors are systematically discussed, offering insights for future research.

The dual role of coastal mangroves: Sinks and sources of microplastics in rapidly urbanizing areas

Mangrove ecosystems are vital for coastal protection, biodiversity, and pollution interception, yet their interactions with microplastics in rapidly urbanizing regions remain underexplored. This study investigated the microplastic dynamics in the Maozhou River and Dasha River, along with the coastal Xiwan Mangrove Park in the Pearl River Estuary, the second largest estuary in China. Samples were collected from mangrove and surrounding areas, identifying microplastics using Fourier-transform infrared spectroscopy (FTIR) and Laser Direct Infrared (LDIR) techniques. Microplastic concentrations ranged from 245.8 to 1562.4 n/m³ in water and 374.3 to 7475.3 n/kg in sediments. The Maozhou River exhibited consistent microplastic levels across varying hydrological conditions, while the Dasha River and Xiwan Mangrove showed greater sensitivity to water flow changes influenced by urban land use. During high-flow periods, urban river microplastic concentrations decreased due to dilution, whereas mangrove areas experienced elevated levels in water from urban runoff, upstream retention, and sediment resuspension, suggesting a potential for outward release. Weaker water dynamics led to increased microplastic accumulation in mangrove sediments. The distribution of microplastic types was influenced by multiple urban pollution sources, with synthetic rubbers linked to urban transportation comprising over 50 % of some samples, peaking at 79 %. These findings underscore the dual role of mangroves as microplastic sinks and potential sources, highlighting the significant impact of hydrological conditions on their function. This study offers new insights into microplastic pollution in urban mangrove ecosystems and emphasizes the urgent need for improved management strategies in coastal areas facing rapid urbanization.

Mechanisms underpinning microplastic effects on the natural climate solutions of wetland ecosystems

Wetland ecosystems are vital carbon dioxide (CO2) sinks, offering significant nature-based solutions for global climate mitigation. However, the recent influx of microplastic (MP) into wetlands substantially impacts key drivers (e.g., plants and microorganisms) underpinning these wetland functions. While MP-induced greenhouse gas (GHG) emissions and effects on soil organic carbon (SOC) mineralization potentially threaten the long-term wetland C-climate feedbacks, the exact mechanisms and linkage are unclear. This review provides a conceptual framework to elaborate on the interplay between MPs, wetland ecosystems, and the atmospheric milieu. We also summarize published studies that validate possible MP impacts on natural climate solutions of wetlands, as well as provide extensive elaboration on underlying mechanisms. We briefly highlight the relationships between MP influx, wetland degradation, and climate change and conclude by identifying key gaps for future research priorities. Globally, plastic production, MP entry into aquatic systems, and wetland degradation-related emissions are predicted to increase. This means that MP-related emissions and wetland-climate feedback should be addressed in the context of the UN Paris Climate Agreement on net-zero emissions by 2050. This overview serves as a wake-up call on the alarming impacts of MPs on wetland ecosystems and urges a global reconsideration of nature-based solutions in the context of climate mitigation.

Expanding sample volume for microscopical detection of nanoplastics

The extent of nanoplastic pollution has raised severe environmental and health concerns. While the means for microplastic detection are abundant, improved tools for nanoplastic detection are called-for. State-of-the-art microscopic techniques can detect nanoplastics down to tens of nanometers, however, only from small sample sizes (typically ∼10μl). In this work, we describe a method that enables sampling of 1 l of seawater by the means of correlative Raman- and SEM-techniques. This is achieved by adapting common microplastic sample purification protocols to suit the nanoplastic study. In addition, we decorate a membrane filter with SERS-property to amplify the Raman signals. Together, the purification method combined with the use of the SERS-activated-membrane-filter enables identification and imaging of individual nanoplastic particles from significantly larger sample sizes than before. In the nanoscale the average recovery rate is 5 %. These results aim to provide useful tools for researchers in the fight against plastic pollution.

Diving into the Depths: Uncovering Microplastics in Norwegian Coastal Sediment Cores

High concentrations of microplastics (MPs) have been documented in the deep-sea surface sediments of the Arctic Ocean. However, studies investigating their high-resolution vertical distribution in sediments from the European waters to the Arctic remain limited. This study examines MPs in five sediment cores from the Norwegian Coastal Current (NCC), encompassing the water-sediment interface and sediment layers up to 19 cm depth. Advanced analytical methods for MP identification down to 11 μm in size were combined with radiometric dating and lithology observations. MPs were present across all sediment cores, including layers predating the introduction of plastics, with concentrations exhibiting significant variation (54-12,491 MP kg-1). The smallest size class (11 μm) predominated in most sediment layers (34-100%). A total of 18 different polymer types were identified across all sediment layers, with polymer diversity and depth correlations varying widely between stations. Our findings suggest that differences in seafloor topography and the impact of anthropogenic activities (e.g., fishing) lead to varying environmental conditions at the sampling sites, influencing the vertical distribution of MPs. This challenges the reliability of using environmental parameters to predict MP accumulation zones and questions the use of MPs in sediment cores as indicators of the Anthropocene.

Reframing the role of communication in consensual and/or ethical (non)monogamies: A proposal for a change in academic terminology

In this essay, I focus on the politics and impacts of naming, especially in the social and human sciences, and more specifically on studies that focus on subordinated or discriminated groups. Through this essay, I argue that naming conventions are some of the most important - and dangerous - tools and acts that researchers have at their disposal and, thus, should be employed with the utmost care. Considering the ongoing discussions - both inside and outside of academia - around the terms "consensual non-monogamies" and "ethical non-monogamies", this essay proposes a novel solution to help create less morally-slanted, and overreaching, hypernyms, or umbrella terms. Here, I provide a rationale for using "explicitness" as a fundamental concept on which to build new classificatory hypernymic terminology. The terminology proposed is equally applicable (and applied) to both monogamies and non-monogamies, and is tripartite: Explicit, Implicit, and Covert. In addition to the terminological proposal, I include in this essay a series of intended limitations and constraints to its usage, its interoperability with other systems, objections to (and responses to) the usage of this system, and advantages of this novel classificatory system, as well as an outline of how this proposal might be improved upon.