Environmental context. Ocean acidification affects marine algae and bacteria, which can produce climate active trace gases such as methane or dimethylsulfide from marine dimethylsulfoxide. We conducted field experiments simulating future ocean acidification, and showed that dimethylsulfoxide concentrations decreased with increasing acidification. Less dimethylsulfoxide in the future can affect climate by influencing the concentration of methane and dimethylsulfide.

Dimethylsulfoniopropionate (DMSP) comprises an important fraction of the organic carbon produced by phytoplankton, and is a major source of carbon and sulfur for heterotrophic bacteria. Here, we show that a non-bioavailable fraction of DMSP recently discovered in coastal waters also exists in oligotrophic open-ocean waters. Taking account of the non-bioavailable pool improved estimates of cycling rates of DMSP and its contribution to bacterial nutrition.

Environmental context. Aluminium may be released into coastal waters in dissolved and particulate forms from urban runoff, industrial discharges and acid sulfate soils. Aquatic organisms may experience toxic effects from exposure to dissolved and particulate aluminium. Therefore, the current study reports the geochemical controls such as speciation, precipitation and adsorption that influence the exposure to these aluminium forms in the field and the laboratory.

Environmental context. Neonicotinoids are under increased scrutiny because they have been implicated in pollinator declines and, more recently, as potential aquatic toxicants. Nevertheless, there is currently little information on concentrations of multiple neonicotinoids in surface water. This paper presents a summary of concentrations of six neonicotinoids in streams from across the United States in both urban and agricultural areas. These environmental data are important in determining the potential risk of neonicotinoids to non-target aquatic and terrestrial organisms.

Environmental context. The general perception that nature does not produce compounds containing halogens – chlorine, bromine, iodine and fluorine – is now known to be erroneous. Modern isolation and identification techniques have led to the discovery of more than 5000 halogen-containing compounds from myriad marine and terrestrial plant and animal sources. Many of these compounds possess extraordinary biological activity, including anticancer, antiviral and antibacterial activity of potential human benefit.

Environmental context. Water associated with coal seam gas is generally of poor quality and thus its management and potential further usage is a subject of concern. In a comprehensive study involving chemical and bioanalytical assessments of coal seam gas associated water, we found that less than 5 % of the biological effects could be explained by chemical analysis. The use of bioanalytical tools to complement chemical analysis is recommended for monitoring the quality of water associated with coal seam gas.

Environmental context. There is growing worldwide interest in the production of oil and gas from deep, shale formations following advances in the technical expertise to exploit these resources such as hydraulic fracturing (fracking). The potential widespread application of hydraulic fracturing has raised concerns over deleterious environmental impacts on fragile water resources. We discuss the environmental management challenges faced by the oil and gas industry, and the opportunities for innovation in the industry.

Environmental context. In marine environments, inorganic arsenic present in seawater is transformed to organoarsenic species, mainly arsenoribosides in algae and arsenobetaine in animals. These transformations decrease the toxicity of arsenic, yet the fate of arsenoribosides and arsenobetaine when marine organisms decompose is unknown. We review the current literature on the degradation of these organoarsenic species in marine systems detailing the drivers behind their degradation, and also discuss the environmental relevance of laboratory-based experiments.

Environmental context. The health of aquatic organisms depends on the distribution of the dissolved forms of chemical components (speciation) and their rates of interaction (dynamics). This review documents and explains progress made using the dynamic technique of diffusive gradients in thin-films (DGT) to meet these challenges of measuring directly chemical speciation and associated dynamics in natural waters. The relevance of these measurements to uptake by biota of chemical forms in soils, sediments and water is discussed with reference to this expanding literature.

Environmental context. Organo–mineral associations represent a fundamental process for stabilising organic carbon in soils. In this study, we employed scanning transmission X-ray microscopy–near edge X-ray absorption fine structure (STXM-NEXAFS) spectroscopy at C, Al and Si K-edges as well as Ca and Fe L-edges to conduct submicrometre-level investigations of the associations of C with mineral components in soils from reduced environments. This study provides the first insights into organo–mineral associations in reduced environments and shows progress towards examining, at the submicrometre level, compositional chemistry and associative interactions between organic matter and soil mineral components.

Environmental context. Most chemical processes in water are either ligand- or electron-exchange reactions. Here the general reactivity trends for ligand-exchange reactions in aqueous solutions are reviewed and it is shown that simple rules dominate the chemistry. These simple rules shed light on most molecular processes in water, including the uptake and degradation of pesticides, the sequestration of toxic metals and the corrosion of minerals.

Environmental context. Himalayan derived arsenic contaminates groundwater across Asia, ranging from the deltas of Ganges-Brahmaputra of Bangladesh to the interior basins of the Yangtze and Yellow Rivers in China, where more than one hundred million people are drinking water with hazardous levels of the toxin. Our ability to predict the distribution and changes in arsenic concentration in aquifers of affected regions has been limited. Here we provide a dynamic model that captures arsenic migration and can be used to forecast changes in groundwater arsenic concentrations.

Environmental context. The low concentration of iron in the oceans limits growth of phytoplankton. Dissolved organic molecules, called ligands, naturally present in seawater, bind iron thereby increasing its solubility and, consequently, its availability for biological uptake by phytoplankton. The characteristics of these ligands are determined indirectly with various mathematical solutions; we critically evaluate the underlying method and calculations used in these determinations.

Environmental context. Carbon tetrachloride in the background atmosphere is a significant environmental concern, responsible for ~10 % of observed stratospheric ozone depletion. Atmospheric concentrations of CCl₄ are higher than expected from currently identified emission sources: largely residual emissions from production, transport and use. Additional sources are required to balance the expected atmospheric destruction of CCl₄ and may contribute to a slower-than-expected recovery of the Antarctic ozone ‘hole’.

Environmental context. Iron-bearing particles in the ocean have attracted interest due to the role of iron as an essential nutrient for microscopic algae, which form the base of the marine food chain. Modern techniques make it possible to analyse individual particles of iron to determine their composition, but the resulting flood of data can be overwhelming. We show a method of simplifying the data to answer such questions as what groups of minerals are present and whether they are different between ocean basins.