Environmental context. Neuropsychiatric pharmaceuticals and illicit drugs in wastewaters are of increasing environmental concern. We compile the recent literature and evaluate the concentrations and profiles of various drugs and their removal efficiencies in wastewater treatment plants. The sewage epidemiology approach, used in the estimation of drug usage in communities, is discussed, and we make recommendations for future research in this area.

Environmental context. Cyanobacteria are ecologically important, photosynthetic organisms that are widely distributed throughout the environment. They play a central role in arsenic transformations in terms of both mineralisation and formation of organoarsenic species as the primary producers in aquatic ecosystems. In this review, arsenic resistance, transport and biotransformation in cyanobacteria are reviewed and compared with those in other organisms.

Environmental context. Laboratory and field studies have both provided evidence for organosulfate formation by esterification of H₂SO₄ with organic compounds in aerosols. Using an outdoor chamber, the production of dialkylsufate was measured for organic aerosols produced by photooxidation of various hydrocarbons in the presence of H₂SO₄ aerosol and NO_x. The formation of organosulfates influences the decrease of both aerosol acidity and aerosol hygroscopicity.

Environmental context. Galvanic corrosion has been recently reported as the main cause of lead contamination in drinking water in urban cities. Conditions that can deter or promote galvanic corrosion, however, are not well understood. Fundamental investigations exploring the mechanisms and processes involved in galvanic corrosion in drinking water could help to implement proper corrective measures to safeguard public health from lead contamination.

Environmental context. Nitrous acid is an important atmospheric trace gas, but the sources and the chemical mechanisms of its production are not well understood. This study explores the effects of ammonia and water on the hydrolysis of nitrogen dioxide and nitrous acid production. The calculated results show that ammonia is more effective than water in promoting the hydrolysis reaction of nitrogen dioxide.

Environmental context. Mangroves dominate at the interface between land and sea, especially along tropical and subtropical coasts. To gain a better understanding of how mangroves respond to various environmental stress factors, we investigated the use of monomethylalkanes as potential chemical tracers for black mangroves. The application of these chemical tracers could elucidate how black mangroves respond to environmental stress such as sea level rise in mixed mangrove environments.

Environmental context. The concentrations of n-alkanes, phthalates and alkylphenols in a dated sediment core from the Yangtze River estuary steadily increased, with evident peaks in c. 1980 and c. 2000. Most of the phthalates and alkylphenols in the core originated from direct industrial and municipal discharges into the lower reaches of the Yangtze River, whereas the n-alkanes were mainly from aquatic and terrestrial plants. The Yangtze River discharge plays an important role in the sedimentary records of organic compounds.

Environmental context. X-ray absorption near-edge spectroscopy (XANES) was applied to give arsenic chemical forms directly in the solid phase of mine wastes from two mine sites, including fluvial dispersion. The arsenic speciation data explained the variation of in vitro bioaccessibility and in vivo bioavailability (rat uptake) data of the mine wastes. The As speciation from XANES fitting supported the hypothesis that when soil intake is adjusted for bioaccessibility, the potential health risk estimate to local residents is significantly lower.

Environmental context. Ibuprofen, a common anti-inflammatory drug and one of many pharmaceuticals sold as a mixture of enantiomers, has recently been found in river and surface waters. There are, however, few analytical methods able to separate and accurately measure ibuprofen enantiomers in environmental matrices. This study reports a method for quantifying ibuprofen enantiomers in sediments and surface water, and applies it to shed light on the degradation and fate of the enantiomers in aquatic systems.

Environmental context. Nitroaromatic compounds constitute an important portion of brown carbon and thereby contribute to the light-absorbing properties of atmospheric aerosols. We report their abundance in Hong Kong over 3 years and show that they were mainly associated with aged biomass burning particles. Knowledge of the abundance and sources of nitroaromatic compounds could assist in evaluating their contribution to brown carbon and in apportioning secondary organic aerosols from biomass burning sources.

Environmental context. Chromate (CrO₄^2–)-containing waste is illegally dumped in some places in the state of Uttar Pradesh, north India, although CrO₄^2– is known to be toxic and carcinogenic. Because CrO₄^2– is leached from the landfills, this study investigated the adsorption of CrO₄^2– by soils. The results indicated that CrO₄^2– is highly leachable and adsorption is inhibited, which leads to contamination of the groundwater and drinking water in this area.

Environmental context. Anthropogenic pollutants deposited in and on snowpacks can undergo many sunlight-driven reactions. These processes have been studied, but typically without measuring the photon flux, the amount of light seen by the reactants, which is needed for comparing results across studies. This work investigates the effects of container albedo, solute location and mechanical ice crushing on the photon flux in laboratory ice samples to understand how these factors might affect photochemical rates.

Environmental context. The safeguarding of water supplies and drinking water is a major issue in the consideration of human health risk management. In this context, an automatic and on-site fractionation system for the detection of organic contaminants has been developed. The main goal of this system is to establish an initial diagnosis by identifying a class of substances involved in a case of pollution.

Environmental context. Ethyne is the lightest of the non-methane hydrocarbons, whose oxidation product, glyoxal, is an important precursor of secondary organic aerosol. This study explores the effects of relative humidity on the formation of secondary organic aerosol under irradiation in the presence of nitrogen oxides and sodium chloride. Results show that relative humidity can enhance aerosol formation, which provides evidence of the contribution of ethyne to organic particles.

Environmental context. Beryllium is a toxic environmental contaminant but has many industrial and scientific applications. Our work explores the effects of soil composition on beryllium retention, focussing on organic matter, mineralogy and pH and concludes that phosphorus and sulfur oxides in addition to soil acidity are strong controls on beryllium mobility. These results aid in future predictions regarding the fate of beryllium in the environment.

Environmental context. Rice is a major human dietary source of arsenic. We identified a novel organoarsenic species, arsinothricin, produced by a bacterium in the rice rhizosphere. This result suggests diverse biochemical dynamics and microbial biodiversity of arsenic metabolism in the rice rhizosphere.

Environmental context. How can we know what happens to organic matter in aquatic environments? Although several compounds exist that can be used to trace the origin and state of organic matter, not many are sufficiently stable and specific to trace degradation processes, but α- and β-amyrins can fulfil that role. Such knowledge will help us better understand and better quantify carbon fluxes in riverine and marine environments.

Environmental context. Natural haloform emissions contribute to stratospheric ozone depletion but there are major unknown or underestimated sources of these gases. This study demonstrates that soil and water at tidal wetlands are important haloform sources, and emissions peak at the forest–marsh transition zone. The low-lying forested wetlands of the south-eastern United States that are facing sea-level rise and seawater intrusion may become hotspots for haloform emission.

Environmental context. Reactions in natural waters such as lakes and streams are thought to be extremely slow in the absence of sunlight (e.g. at night). We demonstrate that in the presence of iron, hydrogen peroxide and certain bacteria (all of which are common in natural waters), certain reactions may occur surprisingly quickly. These findings will help us predict the fate of many compounds, including pollutants, in natural waters at night.

Environmental context. Environmental samples are best analysed in their native state, with minimal sample preparation, to fully understand the complex interactions and processes occurring in environmental systems. Nuclear magnetic resonance spectroscopy is a powerful tool used to study environmental samples but sample pre-treatment is often required to remove water and improve analysis. We introduce an experimental approach to remove water signals from environmental samples in their natural state, which opens the door to intact sample analysis and more environmentally relevant science.