Deciphering the Intricate Control of Minerals on Deep Soil Carbon Stability and Persistence in Alaskan Permafrost.

Understanding the fate of organic carbon in thawed permafrost is crucial for predicting climate feedback. While minerals and microbial necromass are known to play crucial roles in the long-term stability of organic carbon in subsoils, their exact influence on carbon persistence in Arctic permafrost remains uncertain. Our study, combining radiocarbon dating and biomarker analyses, showed that soil organic carbon in Alaskan permafrost had millennial-scale radiocarbon ages and contained only 10%-15% microbial necromass carbon, significantly lower than the global average of ~30%-60%.

Efficient PFAS removal from contaminated soils through combined washing and adsorption in soil effluents.

This study investigates soil washing as a viable strategy to remove poly- and perfluoroalkyl substances (PFAS) from contaminated soils using various washing agents including water, methanol, ethanol, and cyclodextrin ((2-Hydroxypropyl)-β-cyclodextrin HPCD)). Water was less effective (removing only 30 % of PFAS), especially for long-chain hydrophobic PFAS. Methanol (50 % v/v) or HPCD (10 mg g soil) achieved > 95 % PFAS removal regardless of PFAS type, soil size fraction (0-400 µm or 400-800 µm), or experimental setups (batch or column, at liquid/solid (L/S) = 1).

Natural solution for the remediation of multi-metal contamination: application of natural amino acids, and to increase the phytoremediation efficiency.

Natural amino acids (NAA) have been rarely investigated as chelators, despite their ability to chelate heavy metals (HMs). In the present research, the effects of extracted natural amino acids, as a natural and environmentally friendly chelate agent and the inoculation of () and () bacteria were investigated on some responses of quinoa in a soil polluted with Pb, Ni, Cd, and Zn. Inoculation of PGPR bacteria enhanced plant growth and phytoremediation efficiency.

Efficient Immobilization of heavy metals using newly synthesized magnetic nanoparticles and some bacteria in a multi-metal contaminated soil.

Simultaneous application of modified FeO with biological treatments in remediating multi-metal polluted soils, has rarely been investigated. Thus, a pioneering approach towards sustainable environmental remediation strategies is crucial. In this study, we aimed to improve the efficiency of FeO as adsorbents for heavy metals (HMs) by applying protective coatings.

The interplay between microbial communities and soil properties.

In recent years, there has been considerable progress in determining the soil properties that influence the structure of the soil microbiome. By contrast, the effects of microorganisms on their soil habitat have received less attention with most previous studies focusing on microbial contributions to soil carbon and nitrogen dynamics. However, soil microorganisms are not only involved in nutrient cycling and organic matter transformations but also alter the soil habitat through various biochemical and biophysical mechanisms.

Comprehensive Multi-compartment Sampling for Quantification of Long-Term Accumulation of PAHs in Soils.

Long-term accumulation in the soils of ubiquitous organic pollutants such as many polycyclic aromatic hydrocarbons (PAHs) depends on deposition from the atmosphere, revolatilization, leaching, and degradation processes such as photolysis and biodegradation. Quantifying the phase distribution and fluxes of these compounds across environmental compartments is thus crucial to understand the long-term contaminant fate. The gas-phase exchange between soil and atmosphere follows chemical fugacity gradients that can be approximated by gas-phase concentrations, yet which are difficult to measure directly.

Nitrate leaching and its implication for Fe and As mobility in a Southeast Asian aquifer.

The drinking water quality in Southeast Asia is at risk due to arsenic (As) groundwater contamination. Intensive use of fertilizers may lead to nitrate (NO3-) leaching into aquifers, yet very little is known about its effect on iron (Fe) and As mobility in water. We ran a set of microcosm experiments using aquifer sediment from Vietnam supplemented with 15NO3- and 13CH4.

Transformation of zinc oxide nanoparticles in the presence of aluminum oxide with pre-sorbed phosphorus ligands.

Naturally occurring oxides could react with zinc oxide (ZnO) nanoparticles (NPs) and then change its transformation and toxicity to ecological receptors. The reaction may be affected by a variety of environmental factors, yet the relevant processes and mechanisms are limitedly investigated. Natural prevalent ligands, as an important factor, can sorb on natural oxide minerals and change its surface property, finally affecting ZnO NP transformation.

Replacing animal-derived components in in vitro test guidelines OECD 455 and 487.

The evaluation of single substances or environmental samples for their genotoxic or estrogenic potential is highly relevant for human- and environment-related risk assessment. To examine the effects on a mechanism-specific level, standardized cell-based in vitro methods are widely applied. However, these methods include animal-derived components like fetal bovine serum (FBS) or rat-derived liver homogenate fractions (S9-mixes), which are a source of variability, reduced assay reproducibility and ethical concerns.

pH dependence of arsenic speciation in paddy soils: The role of distinct methanotrophs.

Arsenic (As) is a priority environmental pollutant in paddy field. The coupling of arsenate (As(V)) reduction with anaerobic methane (CH) oxidation was recently demonstrated in paddy soils and has been suggested to serve as a critical driver for As transformation and mobilization. However, whether As(V)-dependent CH oxidation is driven by distinct methanotrophs under different pH conditions remains unclear.

Mechanistic modeling indicates rapid glyphosate dissipation and sorption-driven persistence of its metabolite AMPA in soil.

Residual concentrations of glyphosate and its main transformation product aminomethylphosphonic acid (AMPA) are often observed in soils. The factors controlling their biodegradation are currently not well understood. We analyzed sorption-limited biodegradation of glyphosate and AMPA in soil with a set of microcosm experiments.

Simultaneous oxidation of Mn(II) and As(III) on cupric oxide (CuO) promotes As(III) removal at circumneutral pH.

Oxidation of Mn(II) or As(III) by molecular oxygen is slow at pH < 9, while they can be catalytically oxidized in the presence of oxide minerals and then removed from contaminated water. However, the reaction mechanisms on simultaneous oxidation of Mn(II) and As(III) on oxide mineral surface and their accompanied removal efficiency remain unclear. This study compared Mn(II) oxidation on four common metal oxides (γ-AlO, CuO, α-FeO and ZnO) and investigated the simultaneous oxidation and removal of Mn(II) and As(III) through batch experiments and spectroscopic analyses.

Coupled Aerobic Methane Oxidation and Arsenate Reduction Contributes to Soil-Arsenic Mobilization in Agricultural Fields.

Microbial oxidation of organic compounds can promote arsenic release by reducing soil-associated arsenate to the more mobile form arsenite. While anaerobic oxidation of methane has been demonstrated to reduce arsenate, it remains elusive whether and to what extent aerobic methane oxidation (aeMO) can contribute to reductive arsenic mobilization. To fill this knowledge gap, we performed incubations of both microbial laboratory cultures and soil samples from arsenic-contaminated agricultural fields in China.

Tide-Triggered Production of Reactive Oxygen Species in Coastal Soils.

We report an unrecognized, tidal source of reactive oxygen species (ROS). Using a newly developed ROS-trapping gel film, we observed hot spots for ROS generation within ∼2.5 mm of coastal surface soil.

The Next Frontier of Environmental Unknowns: Substances of Unknown or Variable Composition, Complex Reaction Products, or Biological Materials (UVCBs).

Substances of unknown or variable composition, complex reaction products, or biological materials (UVCBs) are over 70 000 "complex" chemical mixtures produced and used at significant levels worldwide. Due to their unknown or variable composition, applying chemical assessments originally developed for individual compounds to UVCBs is challenging, which impedes sound management of these substances. Across the analytical sciences, toxicology, cheminformatics, and regulatory practice, new approaches addressing specific aspects of UVCB assessment are being developed, albeit in a fragmented manner.

Phosphate addition enhances alkaline extraction of glyphosate from highly sorptive soils and aquatic sediments.

Background: Analytical constraints complicate environmental monitoring campaigns of the herbicide glyphosate and its major degradation product aminomethylphosphonic acid (AMPA): their strong sorption to soil minerals requires harsh extraction conditions. Coextracted matrix compounds impair downstream analysis and must be removed before analysis.

Results: A new extraction method combined with subsequent capillary electrophoresis-mass spectrometry for derivatization-free analysis of glyphosate and AMPA in soil and sediment was developed and applied to a suite of environmental samples.

Seasonal Fluctuations in Iron Cycling in Thawing Permafrost Peatlands.

In permafrost peatlands, up to 20% of total organic carbon (OC) is bound to reactive iron (Fe) minerals in the active layer overlying intact permafrost, potentially protecting OC from microbial degradation and transformation into greenhouse gases (GHG) such as CO and CH. During the summer, shifts in runoff and soil moisture influence redox conditions and therefore the balance of Fe oxidation and reduction. Whether reactive iron minerals could act as a stable sink for carbon or whether they are continuously dissolved and reprecipitated during redox shifts remains unknown.

Dilution of concentrations of PAHs from atmospheric particles, bulk deposition to soil: a review.

Polycyclic aromatic hydrocarbons (PAHs) are emitted to the atmosphere by various anthropogenic activities as well as natural sources, they undergo long-range transport, are degraded (e.g., by photolysis) and finally they are deposited onto the surface and potentially accumulate in topsoil.

Long-Term Leaching Behavior of Organic and Inorganic Pollutants after Wet Processing of Solid Waste Materials.

The recycling of mineral materials is a sustainable and economical approach for reducing solid waste and saving primary resources. However, their reuse may pose potential risks of groundwater contamination, which may result from the leaching of organic and inorganic substances into water that percolates the solid waste. In this study, column leaching tests were used to investigate the short- and long-term leaching behavior of "salts", "metals", and organic pollutants such as PAHs and herbicides from different grain size fractions of construction & demolition waste (CDW) and railway ballast (RB) after a novel treatment process.

Utilization and recycling of wood ashes from industrial heat and power plants regarding fertilizer use.

To achieve a sustainable circular economy for wood ash, the reuse of wood ash in agriculture and forestry is important. To evaluate the usability of ash from the combustion of natural as well as waste wood for application as fertilizer, wood fuel and corresponding ash fraction samples (n = 86) of four industrial wood-fired heat and power plants (>20 MW) were investigated. In different ash fractions, the concentrations of heavy metals (As, Cd, Pb, Ni, Tl, Zn) and plant nutrients (N, P, K, Ca) were assessed with regard to relevant legislation from the European Union and from selected European countries (Germany, Austria and Finland).

Biogeochemical Niches of Fe-Cycling Communities Influencing Heavy Metal Transport along the Rio Tinto, Spain.

In the mining-impacted Rio Tinto, Spain, Fe-cycling microorganisms influence the transport of heavy metals (HMs) into the Atlantic Ocean. However, it remains largely unknown how spatial and temporal hydrogeochemical gradients along the Rio Tinto shape the composition of Fe-cycling microbial communities and how this in turn affects HM mobility. Using a combination of DNA- and RNA-based 16S rRNA (gene) amplicon sequencing and hydrogeochemical analyses, we explored the impact of pH, Fe(III), Fe(II), and Cl on Fe-cycling microorganisms.

Temperature dependence of nitrate-reducing Fe(II) oxidation by Acidovorax strain BoFeN1 - evaluating the role of enzymatic vs. abiotic Fe(II) oxidation by nitrite.

Fe(II) oxidation coupled to nitrate reduction is a widely observed metabolism. However, to what extent the observed Fe(II) oxidation is driven enzymatically or abiotically by metabolically produced nitrite remains puzzling. To distinguish between biotic and abiotic reactions, we cultivated the mixotrophic nitrate-reducing Fe(II)-oxidizing Acidovorax strain BoFeN1 over a wide range of temperatures and compared it to abiotic Fe(II) oxidation by nitrite at temperatures up to 60°C.