Environmental context. Volatile selenium compounds from the oceans may ultimately be an important selenium source for agricultural soils. It has been hypothesised that marine algae are responsible for volatile selenium emissions, but in laboratory experiments, we observed minimal volatile selenium production by two marine algae known to produce large amounts of volatile sulfur. Instead, we found hints that bacterial processes may be important in the production of volatile selenium in the oceans.

Environmental context. Arsenic contamination of groundwater is a major environmental problem in many areas of the world. In south-east Asia, iron-rich reducing groundwater mixes with oxidising river water in hyporheic zones, precipitating iron oxides. These oxides can act as a natural reactive barrier capable of accumulating elevated solid-phase concentrations of arsenic.

Environmental context. Copper released by deep-sea hydrothermal vents has been recognised to be partly stabilised against precipitation by its complexation with strong Cu binding ligands. Yet, the sources and nature of these compounds in such environments are still not fully understood. This study shows that the Cu ligands detected are hydrothermally sourced and could be mainly inorganic sulfur species.

Environmental context. Low availability of calcium (Ca²⁺) in soils is one of the major factors in Ca²⁺ deficiency of plants and physiological plant disorders. A device based on functionalised silica was developed for in-situ measurement of the available Ca²⁺ in soils. Application of the proposed device to measure available Ca²⁺ may help to develop and improve agricultural practices.

Environmental context. The behaviour of magnesium, which is an essential element for all living organisms, in terrestrial environments is influenced by natural organic matter. This study shows that magnesium binding by terrestrial humic acids exhibits a pronounced ionic strength-dependence indicating a strong preference for electrostatic binding to humic acids. This interaction is expected to influence the mobility of humic substances and their associated trace elements.

Environmental context. Sphagnum moss is a widespread species in peatlands globally and responsible for a large fraction of carbon storage in these systems. We used synchrotron infrared microspectroscopy to characterise the acid-base properties of Sphagnum moss and the conditions under which calcium uptake can occur (essential for plant tissue integrity). The work allows a chemical model for Sphagnum distribution in the landscape to be proposed.

Environmental context. Chitosan is an abundant natural component of marine life with potential applications as an adsorbant material for pollutants. We investigate the binding behaviour of chitosan, and show that the β-type structure readily chelates metal ions leading to enhanced adsorption of anionic pollutants in the chitosan-metal complex. The results are highly relevant to the removal of anionic organic pollutants from water.

Environmental context. Vanadium, a metal pollutant from fossil fuels and slags, may be toxic, thereby necessitating an understanding of its environmental chemistry. One important factor that controls the mobility and bioavailability of vanadium is its binding to iron oxides. This study focuses on the characterization and modelling of vanadium adsorption onto ferrihydrite. The new model can be used to simulate the transport and bioavailability of vanadium in the environment.

Environmental context. Dissolved organic matter (DOM) plays an important role in influencing the migration and ultimate fate of metals. Different sources of pollution resulted in changes in the structure of sediment DOM in Lake Wuliangsuhai. We investigate the binding properties of DOM with Cu^II and Hg^II using fluorescence quenching combined with two-dimensional correlation spectroscopy (2D-COS) in order to demonstrate the influence of different sources of DOM on metals.

Environmental context. Studying the mechanism of binding between metals and natural organic matter is fundamental to understanding the transport and availability of these contaminants in the environment. The influence of sample treatment on the purification of organic matter showed significant differences in the interaction with metals. The results will contribute to improved modelling of metal binding to organic matter in soils, thereby providing a basis for a more realistic risk assessment.

Environmental context. Mercury (Hg) is a major environmental contaminant due to its toxicity, accumulation and biomagnification along the food chain. We demonstrate that Hg accumulation by biofilms, one possible entry point for Hg into food webs, is rapid and depends on biofilm structure and composition. These findings have important implications for the understanding of Hg bioavailability and effects towards aquatic microorganisms.

Environmental context. In countries where inhabitants are not exposed to arsenic-contaminated drinking water, food is the major source of potentially toxic inorganic arsenic. To complement the existing worldwide dataset on arsenic in rice, data are presented on Australian- and overseas-grown rice, and assessed in terms of possible risk. Only a diet comprising multiple serves of some rice products per day poses a potential risk to young children.