Environmental context. Volatile selenium compounds from the oceans may ultimately be an important selenium source for agricultural soils. It has been hypothesised that marine algae are responsible for volatile selenium emissions, but in laboratory experiments, we observed minimal volatile selenium production by two marine algae known to produce large amounts of volatile sulfur. Instead, we found hints that bacterial processes may be important in the production of volatile selenium in the oceans.

Environmental context. Releases to the aquatic environment from radiological dispersal devices, accidents or leaking waste disposal sites require close monitoring for radionuclide identification. A novel in situ gamma spectrometer deployable on platforms in coastal waters can provide detailed radioisotopic, however, only after the radionuclides are pre-concentrated on efficient sorbents. Here, we report results of particle–water distribution coefficients, K_D, on three novel MnO₂ sorbents using a set of artificial and natural radionuclides in small batch experiments.

Environmental context. The dispersion of antimony in the environment has been misunderstood over the last few decades. Investigating the solubility of naturally forming mineral phases such as nadorite resulted in determination of its limited role in Sb dispersion, providing evidence that nadorite can only limit antimony dispersion in mildly oxidising conditions. Nadorite can only play a significant role in Sb immobilisation in a particular redox window, which forms only a minor part of the framework of Sb dispersion.

Environmental context. Pollution of the aquatic environment by drugs results not only during their manufacture, but also from the excretion of drug residues and the discharge of expired drugs by households and hospitals. The transformation of ciprofloxacin, one of the leading antibiotic drugs, in the presence of surfactants has been investigated. The results provide a better understanding of how ciprofloxacin degrades in aquatic environments by considering the effect of omnipresent surfactants.

Environmental context. The chemical speciation of mercury (Hg) largely controls its biogeochemical cycling and exposure to biota. Here, we investigate the thermodynamic stabilities of complexes formed between inorganic divalent Hg (Hg^II) and 15 biogeochemically relevant low-molecular-mass (LMM) thiol ligands. This information is critical for accurate modelling of the chemical speciation of Hg^II and to clarify the role of Hg^II–LMM thiol complexes in the cycling of Hg in the environment.

Environmental context. Extracellular polymeric substances provide a nucleation site for calcium carbonate and hence are important for bio-calcification processes, with implications for sediment formation and the global carbon cycle. We investigate the calcification potential of polymeric substances produced by five species of cyanobacteria. The results indicate that the protein content and alkaline functional groups of the extracellular polymeric substances may have a significant effect on cyanobacterial calcification.