Environmental context. Nitrate contamination of drinking water quality may be critical, particularly in rural areas where agricultural practices may release large amounts of nitrogen. Knowledge of the source of such contamination, mandatory for water supply management, can be successfully acquired by combining the natural stable isotopes of nitrate, boron isotopic ratios and microbiological indicators.

Environmental context. The organic fraction of atmospheric aerosols is a complex mixture of thousands of species, which play an important role in many atmospheric processes, such as absorbing and scattering solar radiation. We analysed the water-soluble organic fraction of ambient aerosol samples, and quantified over 45 carboxylic acids, sugars, sugar anhydrides and sugar alcohols. The presence of fairly high concentrations of sugars and sugar-alcohols suggests a significant biological input (e.g. pollen, fungi and bacteria) to the water-soluble organic fraction of non-urban aerosols.

Environmental context. Secondary organic aerosols (SOAs), a major organic component of ambient fine particles, contribute to adverse health effects and visibility degradation. Quantification of SOA tracers allows estimation of contributions from specific precursors, which helps the formulation of effective control strategies. We found that malic acid was present in SOA at high abundance in both winter and summer; its seasonally distinct inter-species relationships offer insights into distinct SOA formation pathways.

Environmental context. Lichens have been widely used as biomonitors of atmospheric pollution in the absence of high-density ambient monitoring networks. This study examines the potential for the lichen Xanthoparmelia spp. as a recorder of temporal histories of mercury deposition to the landscape.

Environmental context. Diatoms, unicellular algae that live suspended in the water column, can undergo periods of rapid growth, called blooms. When these algal blooms die, organic compounds including polyunsaturated aldehydes are released to the surrounding water with currently unknown ecological effects. Here we demonstrate that temperature differentially affects the persistence of three major polyunsaturated aldehydes produced by diatoms, and we quantify the removal rates from seawater of these compounds.

Environmental context. Knowledge of metal-chelating agent speciation is integral to our ability to predict and interpret the behaviour of synthetic chelating agents in the environment. Capillary electrophoresis can be used to separate metal–ligand complexes with similar spectroscopic characteristics but different stoichiometries, thereby providing insight into metal–ligand speciation that is not possible by any other technique. Here, we demonstrate the utility of capillary electrophoresis for the determination of metal–ligand stoichiometries and evaluate its limitations.

Environmental context. Antarctica has several scientific research stations located along its coast, where they discharge often untreated sewage containing organic micropollutants. Although degradation of these pollutants by microorganisms is limited by the cold conditions, other pathways such as photodegradation may be significant. Our results indicate that, during the summer, photolysis is a potentially significant degradation pathway for organic micropollutants in Antarctic surface waters, although the rate of loss would depend on ice cover and water depth.

Environmental context. Flocculent material (floc) in freshwater and coastal areas of the Florida Everglades plays an important role in food web dynamics and nutrient cycling. Using biomarkers and pigment chemotaxonomy, we determined the organic matter composition of floc from different environments in the Everglades, and found that it is dominated by local biomass inputs and influenced by hydrological regimes. With the on-going restoration of the Florida Everglades, it is important to gain a better understanding of the biogeochemical dynamics of floc, including its sources, transformations and reactivity.