Biochar alleviated the toxic effects of microplastics-contaminated geocarposphere soil on peanut (Arachis hypogaea L.) pod development: roles of pod nutrient metabolism and geocarposphere microbial modulation.

BACKGROUND: The accumulation of microplastics in agricultural soil poses a threat to the sustainability of agriculture, impacting crop growth and soil health. Due to the geocarpy feature of peanut, geocarposphere soil environment is critical to pod development and its nutritional quality. While the effects of microplastics in the rhizosphere have been studied, their impact on peanut pod in the geocarposphere remains unknown. Biochar has emerged as a potential soil agent with the ability to remediate soil contamination. However, the mechanisms of biochar in mitigating the toxic effects of microplastics-contaminated geocarposphere soil on peanut pod development remain largely unexplored. RESULTS: We evaluated the peanut pod performance and microbiome when facing microplastics contamination and biochar amendment in geocarposphere soil. The results showed that microplastics present in geocarposphere soil could directly enter the peanut pod, cause pod developmental disorder and exert adverse effects on nutritional quality. Aberrant expression of key genes associated with amino acid metabolism, lipid synthesis, and auxin and ethylene signaling pathways were the underlying molecular mechanisms of microplastics-induced peanut pod developmental inhibition. However, these expression abnormalities could be reversed by biochar application. In addition, peanut geocarposphere microbiome results showed that biochar application could restore the diversity of microbial communities inhibited by microplastics contamination and promote the relative abundance of bacteria correlated with pathogen resistance and nitrogen cycle of geocarposphere soil, further promoting peanut pod development. CONCLUSION: This study demonstrated that biochar application is an effective strategy to mitigate the toxic effects of microplastics-contaminated geocarposphere soil on pod development and nutritional quality. © 2023 Society of Chemical Industry.

Microplastics in tea from planting to the final tea product: Traceability, characteristics and dietary exposure risk analysis.

Tea, sold as tea bags or loose tea, is a popular drink worldwide. We quantified microplastics in loose tea during various stages of production, from planting to processing and brewing. The quantity of microplastics in tea ranged from (70-3472 pcs/kg), with the highest abundance detected during processing, mainly in the rolling stage (2266 ± 1206 pcs/kg tea). Scanning electron microcopy revealed scratches and pits on the surface of microplastics fibers from tea plantation soil and processed tea, and their degradation was characterized by cracks and fractures. Exposure risks, based on an estimated dietary intake of 0.0538-0.0967 and 0.0101-0.0181 pcs /kg body weight /day for children and adults, respectively, are considered very low. This study not only evaluates the extent of research on microplastics pollution in tea, but also assess the risk of people's exposure to microplastics through drinking tea.

Critical review of microplastics removal from the environment.

Globally, microplastics pollution has become a serious environmental threat due to their multitude sources, widespread occurrence, persistence, and adverse effects to ecosystem and the human health. Addressing this multifaceted threat requires innovative technologies that can efficiently remove microplastics from the environment. In this review, we first overviewed the source, occurrence, and potential adverse impacts of microplastics to human health. We then identified promising technologies for microplastics removal, including physical, chemical, and biological approaches. A detailed analysis of the advantages and limitations of different techniques was provided. We concluded this review with the current challenges and future research priorities, which will guide us through the path addressing microplastics contamination.

Flooding frequency and floodplain topography determine abundance of microplastics in an alluvial Rhine soil.

Rivers are major pathways for the transport of microplastics towards the oceans, and many studies focus on microplastic abundance in fluvial ecosystems. Although flooding strongly affects transport of microplastics, knowledge about the potential input via floodwaters, spatial distribution, and fate of microplastics in adjacent floodplains remains very limited. In this study, we suggest that local topography and flood frequency could influence the abundance of microplastics in floodplains. Based on this concept, we took soil samples in a Rhine River floodplain in two different depths (0-5 cm and 5-20 cm) along three transects with increasing distance to the river and analysed the abundance of microplastics via FTIR spectroscopy. Flood frequency of the transects was estimated by a combination of hydrodynamic modelling with MIKE 21 (DHI, Hørsholm Denmark) and analysis of time series of water levels. Microplastic abundance per kg dry soil varied between 25,502 to 51,119 particles in the top 5 cm and 25,616 to 84,824 particles in the deeper soil (5-20 cm). The results of our study indicate that local topography and resulting flooding patterns are responsible for the amount of microplastics found at the respective transect. Differences in soil properties, vegetation cover and signs of earthworm activity in the soil profile seem to be related to microplastic migration and accumulation in the deeper soil. The interdisciplinary approach we used in our work can be applied to other floodplains to elucidate the respective processes. This information is essentially important both for locating potential microplastic sinks for process-informed sampling designs and to identify areas of increased bioavailability of microplastics for proper ecological risk assessment.

On the way to reduce marine microplastics pollution. Research landscape of psychosocial drivers.

Current human lifestyle generates enormous amounts of plastics and microplastics that end in the ocean and threaten marine life. Exposure to microplastics seems to threaten human health too. Although the degree of damage is not clear yet, precautionary approach urgently requires a change of societal habits. The objective of this study was to discover emerging issues of priority for psychosocial investigation. For this we have compared the landscape research of Reviews with that of Perspectives articles of the last decade, to identify mismatches that unravel still understudied subjects. Results revealed that circular economy is a focus in Perspectives but is not main topic of current psychosocial research. Regarding the actors involved in the change towards circular economy, although companies are priority in Perspectives current research is focused on consumers. Results suggest the need for more efforts on the investigation of corporative responsibility in the way to stop microplastics pollution.

Abundance, morphology, and removal efficiency of microplastics in two wastewater treatment plants in Nanjing, China.

Municipal wastewater treatment plants (WWTPs) are considered to be major contributors of microplastics to the aquatic environment. Detailed research in China, which is relevant to the local situation, remains in the initial stage. Herein, the microplastic abundance, morphology, and removal efficiency of two WWTPs (C and P) equipped with tertiary treatment processes in different districts of Nanjing, an important city in the Yangtze River Basin, were investigated. The influence of technology, operational parameters, daily capacity, and sewage source and its proportion were discussed. Observations by optical microscope and FT-IR analysis and systematic calculation revealed that the microplastics have four shapes, including fragments, granules, film, and fibers, with various sizes and proportions, which were dependent on wastewater source. The total removal rates of 97.67% and 98.46% for WWTP C and WWTP P, respectively, indicated their highly efficient reduction of microplastics. Treatment technology had a considerable influence on the removal rate, especially the secondary and tertiary processes. However, a large number of microplastics from WWTPs were still released into the environmental waters due to the huge daily capacity. Sewage source determined the concentration, morphology feature, and chemical composition of microplastics to a certain extent. Compared with industrial wastewater, domestic wastewater possibly contained smaller microplastics of polyethylene and polypropylene with lower abundance. Furthermore, additional attention was provided on the flocculation process, drainage system, and treatment efficiency of microplastics with different shapes. This work is expected to provide some technical supports to guide the operation and management of WWTPs.

The effect of microplastics pollution in microalgal biomass production: A biochemical study.

Microplastics (MPs) are widely spread throughout aquatic systems and water bodies. Given that water quality is one of the most important parameters in the microalgal-based industry, it is critical to assess the biochemical impact of short- and long-term exposure to MPs pollution. Here, the microalga Phaeodactylum tricornutum was exposed to water contaminated with 0.5 and 50 mg L-1 of polystyrene (PS) and/or polymethyl methacrylate (PMMA). Results show that the microalgal cultures exposed to lower concentrations of PS displayed a growth enhancement of up to 73% in the first stage (days 3-9) of the exponential growth phase. Surprisingly, and despite the fact that long-term exposure to MPs contamination did not impair microalgal growth, a steep decrease in biomass production (of up to 82%) was observed. The production of photosynthetic pigments was shown to be pH-correlated during the full growth cycle, but cell density-independent in later stages of culturing. The extracellular carbohydrates production exhibited a major decrease during long-term exposure. Still, the production of extracellular proteins was not affected by the presence of MPs. This pilot laboratory-scale study shows that the microalgal exposure to water contaminated with MPs disturbs its biochemical equilibrium in a time-dependent manner, decreasing biomass production. Thus, microalgal industry-related consequences derived from the use of MPs-contaminated water are a plausible possibility.

Ecology of microplastics contamination within food webs of estuarine and coastal ecosystems.

The aim was to describe a methodology developed to study the relationship among the spatio-temporal patterns of habitat utilization, feeding ecology and microplastics (MPs) contamination across the different ontogenetic phases of fishes belonging to different trophic levels and living along the riverine-estuarine-coastal food web. The Goiana Estuary's water column was examined for the seasonal and spatial variation of MPs and their quantification relative to zooplankton, demersal fish species contamination following the same sampling design. The density of MPs in the water column determines their bioavailability. Interest in studies on MPs distribution in relation to spatial and temporal variation of environmental factors and fauna are increasing in quantity and quality. If the ecological strategies presented in this study were replicated in other estuary, comparisons could be made in order to describe how ecosystems work. Standard protocols for sampling, extraction, enumeration and classification of MPs and others pollutant ingested by fishes have been developed and are presented here to encourage comparisons. Standardized and comparable sampling designs and laboratory procedures are an important strategy in order to devise and transfer managerial solutions among different sites and comparisons along time when studying the same environment.

Environmental fate and impacts of microplastics in soil ecosystems: Progress and perspective.

The wide and intensive application of plastics and their derived products has resulted in global environmental contamination of plastic waste. Large-sized plastic litter can be fragmented into microplastics (<5 mm), which have attracted increasing concerns from the general public and scientific communities worldwide. Until recently, the majority of microplastics research reported in literatures has been focusing on the aquatic settings, especially the marine environment, while information about microplastics contamination in terrestrial soil systems is highly insufficient. In this paper, we reviewed the latest data regarding the occurrence of microplastics in terrestrial soils and discussed their potential pathways into the soil environment. We also summarized the currently used methodologies for extraction and characterization of microplastics in soil matrices and evaluated their advantages and limitations. Additionally, we assessed the ecotoxicological consequences of microplastics contamination on soil ecosystems, including the effects on soil physiochemical properties, terrestrial plants, soil fauna, and soil microbes. Finally, based on the most current progress summarized in this review, we suggested several directions for future research on microplastics in soil ecosystems.