Soils are essential components of terrestrial ecosystems that experience strong pollution pressure. Microplastic contamination of soils is being increasingly documented, with potential consequences for soil biodiversity and function. Notwithstanding, data on effects of such contaminants on fundamental properties potentially impacting soil biota are lacking. The present study explores the potential of microplastics to disturb vital relationships between soil and water, as well as its consequences for soil structure and microbial function. During a 5-weeks garden experiment we exposed a loamy sand soil to environmentally relevant nominal concentrations (up to 2%) of four common microplastic types (polyacrylic fibers, polyamide beads, polyester fibers, and polyethylene fragments). Then, we measured bulk density, water holding capacity, hydraulic conductivity, soil aggregation, and microbial activity. Microplastics affected the bulk density, water holding capacity, and the functional relationship between the microbial activity and water stable aggregates. The effects are underestimated if idiosyncrasies of particle type and concentrations are neglected, suggesting that purely qualitative environmental microplastic data might be of limited value for the assessment of effects in soil. If extended to other soils and plastic types, the processes unravelled here suggest that microplastics are relevant long-term anthropogenic stressors and drivers of global change in terrestrial ecosystems.

Microplastics can affect biophysical properties of the soil. However, little is known about the cascade of events in fundamental levels of terrestrial ecosystems, i.e., starting with the changes in soil abiotic properties and propagating across the various components of soil–plant interactions, including soil microbial communities and plant traits. We investigated here the effects of six different microplastics (polyester fibers, polyamide beads, and four fragment types: polyethylene, polyester terephthalate, polypropylene, and polystyrene) on a broad suite of proxies for soil health and performance of spring onion (Allium fistulosum). Significant changes were observed in plant biomass, tissue elemental composition, root traits, and soil microbial activities. These plant and soil responses to microplastic exposure were used to propose a causal model for the mechanism of the effects. Impacts were dependent on particle type, i.e., microplastics with a shape similar to other natural soil particles elicited smaller differences from control. Changes in soil structure and water dynamics may explain the observed results in which polyester fibers and polyamide beads triggered the most pronounced impacts on plant traits and function. The findings reported here imply that the pervasive microplastic contamination in soil may have consequences for plant performance and thus for agroecosystems and terrestrial biodiversity.

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Process waters obtained from hydrothermal carbonization (HTC) of wheat straw, a biogas digestate derived thereof, and four woody biomass feedstocks were quantified regarding the total organic carbon (TOC) and selected organic compounds. HTC runs revealed that TOC loads were largely unaffected by process severity or type of feedstock whereas the C2–C6 fatty acids, determined by GC, displayed clear effects of temperature and feedstock. HPLC demonstrated simultaneously the initial increase and subsequent consumption of cellulose‐derived furfural and 5‐hydroxymethylfurfural as well as the increase of the lignin‐derived 2‐methoxyphenol. 2‐Methylbenzofuran, an example for a substance potentially harmful to aquatic biota, was observed in high concentration in the HTC liquor from wheat straw‐based feedstocks.

The antioxidant efficacy of various oxidation inhibitors in low erucic acid rapeseed oil has been studied in a screening test at 130°C by an induction period method. Hindered monophenols, sulphides, phosphites, aromatic amines and zinc dithiophosphates yielded no or only marginal stabilising effects. Remarkably increased oxidation stabilities were observed with certain hindered bisphenols, polyhydroxybenzenes, zinc and bismuth dithiocarbamates. In high oleic sunflower oil with a lesser portion of multiple unsaturation, these additives induced relatively longer induction periods. Mixtures of zinc dithiocarbamates and 4,4′‐methylenebis‐(2, 6‐di‐tert‐butylphenol) or octylated di‐phenylamine, as well as compositions of all three compounds, exhibited synergistic effects. Under the conditions employed these additives were distinctly superior to commercially recommended formulations. A mechanistic concept of the antioxidant action of zinc dithiocarbamate is briefly discussed.