Environmental context. The detection and characterisation of engineered nanomaterials in the environment is essential for exposure and risk assessment for this emerging class of materials. However, the ubiquitous presence of naturally occurring nanomaterials presents a unique challenge for the accurate determination of engineered nanomaterials in environmental matrices. New techniques and methodologies are being developed to overcome some of these issues by taking advantage of subtle differences in the elemental and isotopic ratios within these nanomaterials.

Environmental context. Characterisation of nanoparticles in terms of number concentration and aggregation state is essential for interpreting data from toxicological tests. These parameters have never been measured in situ in tests carried out in soil matrices. Here, environmental scanning electron microscopy imaging is evaluated for particles in soil, and a method for determining the number concentrations by counting the particles in the images is developed.

Environmental context. Legacy contamination from mining operations is a serious and complex environmental problem. We examine a former uranium mine where groundwater leaving the site enters a stream with chemically dramatic effects resulting in a fundamental change in the way contaminant metals are transported to the surface environment. The results are important for our understanding of how these contaminants are dispersed, and how they could interact with the biosphere.

Environmental context. Nanoparticles are contained in many commercialised products, but the lack of validated methods to assess their potential release into the environment hampers our ability to perform a reliable risk assessment. Equipment to simulate aging is available, but the challenge is to sample released entities, and to analyse those fragments with suitable nano-analytics. We describe methods to characterise the degradation and surface accumulation of nanoparticles, and to quantify fragments released during UV irradiation of polymer nanocomposites.

Environmental context. Silver nanoparticles discharged with municipal wastewater may contaminate surface waters and harm aquatic ecosystems. We applied several analytical techniques to investigate the persistence and transformation of silver nanoparticles in a natural lake environment, and show, through multiple lines of evidence, that they persisted in lake water for several weeks after addition. The nanoparticles were releasing silver ions through dissolution, but these toxic ions were likely binding with natural organic matter in the lake water.

Environmental context. Volatile organic compounds are precursors of ozone, a pollutant with adverse environmental effects. It is important to determine the associations between the various sources of volatile organic compounds and ozone levels because emission controls are based on sources. We estimated the contributions of specific sources of volatile organic compounds on ozone levels using both measurements and statistical models, and found that traffic is the largest source even in events when wildfire smoke is present.

Environmental context. Structural and conformational information on organic matter–clay complexes and whole soils was obtained using different NMR methods. The results show that organic matter interactions with clay mineral surfaces determine the accessibility of specific organic matter components at the soil–water interface. This physical conformation may also play a role in soil biogeochemical processes and binding to pollutants in terrestrial environments.