Environmental context. We are entering an epoch – the Anthropocene – in which human activity is changing the face of the planet. To stabilise climate, we may consider deliberate intervention into Earth’s systems, on a global scale. Responsible stewardship requires that we develop a safe, economic and environmentally acceptable means of sequestering CO₂ from the atmosphere.

Environmental context. The nitrate oxygen isotope anomaly has been suggested as a tool for quantifying the atmospheric input of this essential nutrient to terrestrial environments. However, it is calculated that the most important transport process in minerals, diffusion, may also be responsible for measurable anomalies. The signal in Chilean nitrate minerals could be associated with diffusion during crystal growth so the belief that the nitrate is of atmospheric origin is therefore questioned.

Heavy metals are non-degradable and are therefore a severe and persistent environmental menace. The toxic effects of Pb were investigated using NMR to determine the metabolic changes in earthworms exposed to Pb. The approach using ¹H NMR to analyse earthworm metabolomics demonstrated great potential as a reliable, rapid and convenient tool to assess the toxicity of heavy metals and could be used to identify warning signs of heavy metal contamination of soil.

Environmental context. The fate and behaviour of pollutants such as pesticides, metals and nanoparticles in natural waters will influence their effects on the environment and human health. Owing to the complexity of natural waters and suspended particulate matter (SPM) that can interact with pollutants, as well as low pollutant concentrations, determination of pollutant fate and transport is non-trivial. Herein, we report a characterisation of the Rhone River chemistry to provide insight into selecting SPM analogues for experimental and modelling approaches.

Environmental context. The extent to which organic matter decomposition generates carbon dioxide or methane in anaerobic ecosystems is determined by the presence or absence of particular electron acceptors. Evaluating carbon dioxide and methane production in anaerobic incubation of peat, we found that organic matter predominated as an electron acceptor over considered inorganic electron acceptors. We also observed changes in organic sulfur speciation suggesting a contribution of organic sulfur species to the electron-accepting capacity of organic matter.

Environmental context. At sediment surfaces, the availability of oxygen is controlled by its downward transport from the water surface and its consumption in microbial metabolism. Microorganisms can also consume substances other than oxygen to dispose of the surplus charge that is generated during microbial metabolism. We investigate the complex dynamics of these other substances when the oxygen availability fluctuates, and thereby contribute to the mechanistic understanding of oxygen-consuming processes in aquatic environments.

Environmental context. Goethite, commonly found in soils, is often partially substituted by Al and strongly influences the mobility of arsenic in the environment. The adsorption of As^V onto goethites with increasing Al substitution was explored, finding that Al incorporation decreases As^V sorption per gram of adsorbent, and that a low level of Al incorporation enhances the adsorption per unit area. Structures of the complexes formed between As^V and the oxy(hydr)oxide surface, at different pH values, are proposed by studying the changes in the surface charges of the adsorbed and non-adsorbed substituted and non-substituted goethites.

Environmental context. Although pharmaceuticals are found in wild fish, there is no consensus as to which fish tissue to use when measuring the pharmaceutical concentrations. Using the psychiatric pharmaceutical oxazepam in Eurasian perch as an example, we found that oxazepam was distributed in the perch tissues in the following order of concentration: muscle < liver = brain < blood plasma. These results help to interpret and compare previous studies, and provide guidance for future studies.

Environmental context. Biochar amendment in soil can sequester carbon but may also stimulate microbial activity, potentially enhancing soil organic matter degradation. We incubated biochar in a temperate forest soil and characterised the soil organic matter composition using molecular-level biomarker and nuclear magnetic resonance techniques. Biochar amendment altered the native soil organic matter composition and decreased the concentration of easily degradable soil organic matter components.

Environmental context. Owing to its remoteness, Antarctica is an excellent natural laboratory for conducting studies on the behavior of marine aerosols and for monitoring the impact of global human activities. The aim of this study is to provide an extensive chemical characterization of Antarctic aerosol and to investigate its sources. A distinction among anthropogenic, crustal, and biogenic sources was defined using several chemical markers.

Environmental context. Dissolved organic nitrogen (DON) often constitutes the largest portion of the dissolved nitrogen pool, yet is a commonly overlooked nutrient source in aquatic systems. Terrestrially aged Eucalyptus camaldulensis, a common Australian lowland leaf-litter species, rapidly released proteinaceous DON during the first 24 h of leaching. The results indicate that terrestrial leaf litter may play an important role in satisfying nutrient demand within aquatic systems through both direct deposition and floodplain interactions.

Environmental context. China has been experiencing severe particulate pollution and frequent haze episodes in recent years. We compare the molecular composition of urban organic aerosols on clear and hazy days in Beijing by high-resolution mass spectrometry. The comparative study shows that oxidation, sulfation and nitrification processes actively involve precursors of anthropogenic origin in the Beijing polluted urban atmosphere.