Environmental context. Carbon and nitrogen isotopes in terrestrial organic matter are widely used for reconstructing past environments, but organic matter is exposed to degradation as soon as it is deposited during what is called early diagenesis. This study explores the effects of this process on organic carbon and nitrogen isotopes, and concludes that it homogenises an environmental signal by integrating all their components. Thus, early diagenesis may not preclude paleoenvironmental reconstructions.

Environmental context. Nitrous acid (HONO) has long been recognized as an important atmospheric pollutant, with the reaction of HOSO + NO₂ being a source of HONO. We explore the effects of an additional water or ammonia molecule on this reaction. Calculations show that the ammonia molecule has a more effective role than the water molecule in assisting the reaction.

Environmental context. The environmental behaviour of trace metals in soils and waters largely depends on the chemical form (speciation) of the metals. Speciation software programs combining models for the binding of metals to soil and sediment constituents are powerful tools in environmental risk assessment. This paper describes a new combination of speciation software with a fitting program to optimise geochemical model parameters that describes proton and metal binding to humic substances.

Environmental context. Cerium, a Technology Critical Element with many technical, agricultural, and medicinal applications, is increasingly being discharged to the environment. One of the best ways to remove cerium from wastes is its fixation into inexpensive bulk material such as vermiculite. This paper investigates the mechanism of Ce^III and Ce^IV uptake and capture by vermiculite in neutral and acidic aqueous solutions.

Environmental context. Eutrophication caused by excessive inputs of phosphorus is a prevalent global environmental problem. Reactive phosphorus released from sediments was measured by two new in situ passive sampling techniques capable of high-resolution measurements of phosphorus concentration. The methods provide the scientific evidence for solving the problems associated with deteriorating surface water quality.

Environmental context. Terrestrial environments receiving trace metal contaminants are often impacted by more than one metal. This study demonstrates the adaptation of an ion-exchange technique to simultaneously obtain Cu²⁺, Ni²⁺ and Zn²⁺ activities in soil extracts. These measurements can be used to better understand and predict the behaviour and bioavailability of soil metals in metal–mixture contamination scenarios.

Environmental context. Natural organic matter in surface waters is a transport vector for environmental pollutants with both its concentration and composition influencing pollutant fate. Characterisation of organic matter in surface waters, crucial to understanding pollutant transport, should also account for spatial variation along the water source. The present work characterises the natural organic matter in the Rhone River and describes the distributions of various pesticides and metabolites along the river.