Papers

Effects of plastic residues and microplastics on soil ecosystems: A global meta-analysis

Global meta-analysis of 6,223 observations found that plastic residues and microplastics decreased soil water movement by 14%, dissolved organic carbon by 10%, and total nitrogen by 7%, while reducing plant height by 13% and root biomass by 14%. Soil animal body mass and reproduction decreased by 5% and 11% respectively, though soil enzyme activity increased by 7-441%.

Nanoplastic and phthalate induced stress responses in rhizosphere soil: Microbial communities and metabolic networks

This study looked at how nanoplastics and a common plasticizer chemical (DBP) together affect the soil around dandelion roots, finding that the combination reduced soil quality and reshaped the communities of bacteria and fungi. The disruption of soil microbes and their chemical processes matters because it can affect the safety and quality of plants used for food and medicine.

Microplastics as an emerging threat to plant and soil health in agroecosystems

LDPE and biodegradable PLA-PBAT plastics differentially affect plant-soil nitrogen partitioning and dynamics in a Hordeum vulgare mesocosm

Researchers compared how conventional LDPE plastic and biodegradable PLA-PBAT plastic affect nitrogen cycling in soil where barley was growing. LDPE microplastics reduced the amount of fertilizer nitrogen taken up by plants and increased nitrogen lost through leaching, while biodegradable plastics boosted microbial activity in the soil. The study shows that different types of plastic pollution affect soil nutrient cycles in different ways, which could influence both crop nutrition and groundwater contamination.

One hundred priority questions for advancing seagrass conservation in Europe

European researchers identified 100 key questions that need answering to better protect seagrass ecosystems, which are underwater meadows vital for carbon storage, biodiversity, and coastal protection. While not directly about microplastics, seagrass beds act as filters that can trap microplastic pollution and are themselves threatened by it. Protecting these ecosystems could play an important role in reducing microplastic contamination in coastal waters.

Current challenges on the widespread adoption of new bio-based fertilizers: insights to move forward toward more circular food systems

This review examines the challenges of adopting bio-based fertilizers made from food and agricultural waste as replacements for synthetic mineral fertilizers. While bio-based fertilizers can improve soil health and reduce reliance on finite resources, barriers include inconsistent nutrient content, concerns about contaminants like microplastics and heavy metals in waste-derived products, and the need for farmer-friendly application methods. The study is relevant because sewage sludge used in some fertilizers is a known source of microplastic contamination in farmland.

Microplastics alter multiple biological processes of marine benthic fauna

This meta-analysis pools data from multiple studies to show that microplastics harm seafloor organisms across all life stages, with embryos being the most vulnerable. The research found negative impacts on feeding, growth, reproduction, and survival in bottom-dwelling marine animals, which matters because these creatures play a critical role in ocean food webs that ultimately affect human food sources.

Potential ecological risk assessment of microplastics in coastal sediments: Their metal accumulation and interaction with sedimentary metal concentration

Scientists surveyed 21 locations along Qatar's coastline and found microplastics in sediments at every site, with most particles showing signs of chemical degradation from the harsh environment. The microplastics had adsorbed metals from the surrounding environment, though at lower concentrations than those found in the sediment itself. This research shows how microplastics in coastal areas can act as carriers for toxic metals, potentially increasing the exposure of marine organisms and, through the food chain, humans.

Leaching of phthalate acid esters from plastic mulch films and their degradation in response to UV irradiation and contrasting soil conditions

Researchers studied how phthalate plasticizers leach from agricultural mulch films and break down under different soil conditions and UV exposure. They found that sunlight accelerates the release of these chemicals from plastic, while soil microbes play a major role in their subsequent degradation. The study highlights how plastic mulch in farming can be a continuous source of potentially harmful chemical additives entering the soil environment.

Behavior of microplastics and plastic film residues in the soil environment: A critical review

This critical review examines the behavior and fate of microplastics in soil environments, particularly in agricultural land where plastic mulch films and biosolid applications have left a legacy of contamination. Researchers note that many soils now contain an estimated 50 to 250 kilograms of plastic residue per hectare, but the difficulty of extracting and measuring plastic particles from soil has limited our understanding of the risks. The study calls for improved methods to assess whether soil-borne microplastics can migrate to groundwater, air, and the human food chain.

Settling and rising velocities of microplastics: Laboratory experiments and lattice Boltzmann modeling

This study measured how different types of microplastics sink or float in water, testing how particle size, density, water temperature, salinity, and bacterial growth affect their movement. Biofilm growth on microplastics significantly changed their behavior, slowing sinking speeds and even causing some buoyant particles to reverse direction and sink. Understanding how microplastics move through water is important for predicting where they end up in the environment and how they might enter drinking water sources.

Effect thresholds for the earthworm Eisenia fetida: Toxicity comparison between conventional and biodegradable microplastics

Increasing concentration of pure micro- and macro-LDPE and PP plastic negatively affect crop biomass, nutrient cycling, and microbial biomass

Researchers grew maize in soil mixed with pure polyethylene and polypropylene plastics of different sizes and found that higher plastic concentrations reduced crop biomass, disrupted nutrient cycling, and decreased soil microbial activity. Even plastics without chemical additives negatively affected plant growth, showing that the plastic material itself is harmful to soil health. This matters for food security because agricultural soils are accumulating plastic from mulch films and other farming materials.

Potential sources and occurrence of macro-plastics and microplastics pollution in farmland soils: A typical case of China

This study provides the first comprehensive survey of plastic pollution in Chinese farmland soil, analyzing data from 163 publications covering 728 sites. The average microplastic abundance was 4,537 particles per kilogram of dry soil, with agricultural plastic films and organic waste being the biggest sources. Since China is the world's largest user of agricultural plastics, these findings highlight how farming practices can lead to significant microplastic contamination of the soil that grows our food.

Earthworms mediate the influence of polyethylene (PE) and polylactic acid (PLA) microplastics on soil bacterial communities

Researchers studied how earthworms interact with both conventional polyethylene and biodegradable PLA microplastics in soil over 120 days. Both types of microplastics changed the composition of soil bacterial communities, but in different ways, and earthworms appeared to mediate these effects by consuming bacteria or altering soil conditions. The findings show that even biodegradable plastics disrupt soil ecosystems, and that soil organisms play a complex role in how microplastics affect the underground environment.

Why do some bird species incorporate more anthropogenic materials into their nests than others?

This review examines why certain bird species incorporate plastic and other human-made materials into their nests more than others, considering factors like habitat, diet, and nesting style. While the materials can sometimes provide benefits like pest deterrence, they also carry risks including entanglement and reduced insulation. The study illustrates how pervasive plastic pollution has become in natural ecosystems, with wildlife interactions serving as indicators of environmental microplastic contamination.

Microplastics in European sea salts – An example of exposure through consumer choice and of interstudy methodological discrepancies

Researchers analyzed 13 European sea salts and found microplastics in all of them, with industrially harvested salts containing more particles than traditionally harvested ones. They estimated that a person absorbs about 14 micrograms of microplastics annually from all salt consumption, with a quarter attributable to choosing sea salt specifically. The study also found that differences in research methods across studies make it difficult to compare microplastic levels in salt worldwide.

Bioplastic (PHBV) addition to soil alters microbial community structure and negatively affects plant-microbial metabolic functioning in maize

Researchers tested the effects of adding a biodegradable bioplastic to soil on maize growth and soil microbial communities. They found that the bioplastic altered soil microbial community structure and negatively affected the metabolic interactions between plants and soil microbes, even at relatively low concentrations. The study raises concerns that biodegradable plastic alternatives may not be as benign to soil ecosystems as commonly assumed.

The long-term uncertainty of biodegradable mulch film residues and associated microplastics pollution on plant-soil health

This study investigated the long-term effects of biodegradable mulch film residues and their associated microplastics on soil health and plant growth. Researchers found that as biodegradable films break down faster than conventional plastics, they may actually generate more microplastics in a shorter timeframe. The results raise concerns that biodegradable mulch films, often promoted as eco-friendly alternatives, could pose their own risks to agricultural soil ecosystems.

Soil application of PE and PLA microplastics alter earthworm (Eisenia nordenskioldi) gut bacterial community and soil microbiome-metabolome dynamics

Researchers compared the effects of conventional polyethylene and biodegradable polylactic acid microplastics on earthworm gut bacteria and soil ecosystems over 120 days. They found that polyethylene had a more significant impact on soil microbial communities and metabolic processes than PLA at environmentally relevant concentrations. The study highlights that both types of microplastics can alter soil ecosystems, but conventional plastics may pose greater ecological risks.

Separation and Identification of Conventional Microplastics from Farmland Soils

Researchers developed a low-cost, accessible method for extracting and identifying microplastics from farmland soils using density separation, fluorescent staining, and infrared spectroscopy. The protocol achieved recovery rates between 82% and 101% across different soil types and particle sizes. This standardized approach could help scientists worldwide compare results more reliably and give policymakers better data on agricultural microplastic contamination.

The combined effects of ocean warming and microplastic pollution on marine phytoplankton community dynamics

Researchers studied the combined effects of microplastic pollution and rising ocean temperatures on tiny marine plants called phytoplankton. While microplastics alone had minimal impact at current temperatures, when combined with warmer water conditions, phytoplankton biomass dropped by 41% and diversity fell by nearly 39%. The study suggests that climate change may dramatically amplify the harmful effects of microplastic pollution on the ocean organisms responsible for a significant portion of global carbon capture.

The agricultural plastic paradox: Feeding more, harming more?

This review examines the trade-off between the agricultural benefits of plastic film mulch, which helps feed an estimated 85 million additional people in China alone, and the growing microplastic contamination it causes in farmland soils. Researchers found that current studies on the effects of mulch-derived microplastics use inconsistent methods and often unrealistically high concentrations, making it difficult to assess the true risks. The study calls for standardized research approaches to better understand whether the agricultural benefits of plastic mulch outweigh its environmental costs.

Field application of biodegradable microplastics has no significant effect on plant and soil health in the short term

Researchers conducted a field study to test whether biodegradable polylactic acid microplastics affect oat and soybean growth or soil health over one growing season. They found that neither fiber nor powder forms of the biodegradable microplastics had significant effects on soil enzyme activities, plant biomass, or crop yield. The study suggests that biodegradable microplastics may not pose a significant short-term threat to agricultural ecosystems and could serve as a viable alternative to conventional plastics.