Environmental context. Both inorganic and organic arsenic species are toxic to the environment when labile. The Diffusive Gradients in Thin Films technique, equipped with ferrihydrite binding gel enables measurement of labile arsenic species from water and soil solutions. This study indicated that labile arsenic species are quantitatively adsorbed to the gel, and that they are stable for up to 2 weeks following deployment.

Environmental context. Fulvic acids account for a large proportion of dissolved organic matter in aquatic environments and affect the transportation and bioavailability of organic and inorganic pollutants. The structural and spectroscopic characteristics of fulvic acids mainly depend on the sources, seasons and anthropogenic activity. We present an advanced approach using fluorescence spectroscopy as a rapid and cost-effective method to investigate the composition, properties and origins of fulvic acids.

Environmental context. The speciation of trace metals in the environment is often dominated by complexation with natural organic matter such as humic acid. Humic acid is a negatively charged soft nanoparticle and its electrostatic properties play an important role in its reactivity with metal ions. The presence of major cations, such as Ca²⁺, can decrease the effective negative charge in the humic acid particle body and thus modify the chemodynamics of its interactions with trace metal ions.

Environmental context. Pollution of the aquatic environment by oxytetracycline can lead to microbial resistance thereby compromising the efficacy of current medication regimes. Adsorption by colloidal and sediment particles reduces the rate at which oxytetracycline degrades, whereas the longer the antimicrobial remains in the aquatic environment, the greater the danger of microbial resistance. There is need therefore for a fuller understanding of the kinetics of degradation of oxytetracycline in aquatic ecosystems before measures for mitigating pollution by the antimicrobial can be designed.

Environmental context. Heavy metal pollution is a worldwide environmental concern, and the risk depends not only on their total concentration, but also on their chemical speciation. Based on state-of-the-art geochemical modelling, we pinpoint the heavy metal pools approached by the widely used sequential extraction method. The finding of this paper can help users of sequential extraction methods to better interpret their results.

Environmental context. Water associated with coal seam gas is generally of poor quality and thus its management and potential further usage is a subject of concern. In a comprehensive study involving chemical and bioanalytical assessments of coal seam gas associated water, we found that less than 5 % of the biological effects could be explained by chemical analysis. The use of bioanalytical tools to complement chemical analysis is recommended for monitoring the quality of water associated with coal seam gas.

Environmental context. Dynamic speciation of an element in a natural medium is essential for understanding its availability. The technique of diffusion gradients in thin films (DGT) has become a widely used tool for in situ environmental studies, being applied to determine fluxes of metal cations, anions, organics and nanoparticles. The interpretation of the measurements with suitable physicochemical models gives valuable insights into the behaviour of the system.

Environmental context. Engineered nanomaterials (e.g. silver, zinc oxide and copper oxide) are being widely used in many consumer products such are cosmetics, food packaging and textiles. During their usage and treatment, they will be released to natural waters and partly dissolve, depending on the water type and nanomaterial characteristics. These nanomaterials may thus have some toxic effects to aquatic organisms and indirectly to humans because of higher concentrations of dissolved silver, zinc and copper in natural waters.

Environmental context. During the electrochemical analysis of natural waters, the Hg electrode could become the site for surface metal sulfide formation, such as FeS, which can have significant influence on the voltammetric determination of Fe^II. Reduction of Fe^II in such conditions can occur both on the bare Hg surface and on the FeS-modified Hg surface. Until recently, measurements of Fe^II have considered only the signal obtained from reduction on the bare Hg surface, and hence may have underdetermined the true Fe^II content of natural samples.

Environmental context. Hydraulic fracturing fluids, used in large volumes by the coal seam gas mining industry, are potentially present in the environment either in underground formations or in mine wastewater (produced water). Previous studies of the human health and environmental effects of this practice have been limited because they use only desktop methods and have not considered combined mixture toxicity. We use a novel in vitro method for toxicity assessment, and describe the toxicity of a hydraulic fracturing fluid on a human gastrointestinal cell line.

Environmental context. The treatment of extremely saline, high-strength wastewaters while producing electricity represents a great opportunity to mitigate environmental effects and recover resources associated with wastes from shale oil and gas production. This paper demonstrates that extreme halophilic microbes can produce electricity at salinity up to 3- to 7-fold higher than sea water.