Alkyl nitrates are considered to be important intermediates in the atmospheric hydrocarbons–nitrogen oxides–ozone cycle, which significantly determines air quality and nitrogen exchange between the atmosphere and the Earth’s surfaces. The present laboratory study investigates reaction products of alkyl nitrates to elucidate their photochemical reaction mechanisms in the atmosphere. The results provide a better understanding of the role played by alkyl nitrates in the atmospheric environment.

Elevated levels of selenium and arsenic in the environment as a result of anthropogenic activities are creating significant concerns for the health of aquatic ecosystems. How biofilms, or aquatic microbial communities, interact with and chemically modify selenium and arsenic species has been examined. The results demonstrate that selenium and arsenic induce structural changes in biofilms, and concurrently undergo extensive biotransformation, in most cases to less bioavailable species.

Understanding the uptake of mercury by bacteria is essential for predicting the amount of toxic methyl mercury formed in the environment. This study shows that the uptake of mercury by a whole-cell bacterial biosensor as a function of a strong ligand was greater than predicted by chemical speciation measurements or equilibrium calculations. These results call into question the use of chemical measurements and equilibrium modelling for predicting the toxicity of metals to living organisms in the environment and suggest that direct biological methods yield more accurate results.

Hexabromocyclododecanes are widely used as additive brominated flame retardants in thermal insulation building materials, upholstery textiles and electronic products. Dongjiang River is located at the Pearl River Delta, one of the most highly industrialised regions in China, which was seriously polluted by hexabromocyclododecanes. Higher levels of hexabromocyclododecanes in Dongjiang River will pose a serious threat to ecological health in this region.

Fine particles affect air quality locally, regionally and globally. Determining the sources of fine particles is therefore critical for developing strategies to reduce their adverse effects. Advanced data analysis techniques were used to determine the sources of fine particles at two sites, providing information for future pollution reduction strategies not only at the study sites but in other areas of the world as well.

The environmental fate of a particular contaminant can be influenced by the presence of other chemicals. It is shown that the photodegradation in water of benzotriazole, a common household and industrial chemical, is reduced in the presence of a sunscreen compound. Thus, contaminants such as benzotriazole may persist longer in the environment in the presence of chemicals designed to filter ultraviolet rays, such as those used in sunscreens.

Analysis of soil organic matter is important for understanding turnover and stabilisation processes of organic carbon in soils. Capillary electrophoresis is used here to investigate humic acids from soils of diverse forest sites, and show that the patterns of signals are indicative of soil characteristics. The method provides useful information of soil types and complements the existing set of methods for humic acid characterisation.

Leaf litter can be found at the Earth’s surface in large quantities, and has the potential to release significant amounts of volatile compounds into the atmosphere where they influence atmospheric chemistry and local air quality. This study investigates the influence of UV radiation on the emission of C₂–C₅ hydrocarbons from leaf litter. Research on volatile compound emissions from leaf litter is limited, but essential for establishing their global budgets and understanding atmospheric chemistry.

Mercury is classified as a priority pollutant owing to the biomagnification of its methylated species along food chains and the consequent effects on top consumers. The pH of natural waters affects many of the biogeochemical processes that control mercury accumulation in aquatic organisms. Here, evidence is presented that pH affects mercury uptake by unicellular algae, primary producers in aquatic food chains, thereby providing a new example of the pervasive influence of pH on the mercury biogeochemical cycle.