Environmental context.  Cobalt is a technologically critical element due to its uses in the green energy transition, but its cycling is poorly constrained in surface environments. We determined the form of cobalt in naturally enriched soils and found that it is commonly associated with manganese as mixed oxide nanoparticles. These findings demonstrate that the behaviour of critical elements such as cobalt in the environment is in part governed at the nanoscale. (Photograph by O. P. Missen, 11 July 2022.)
Environmental context. Arsenic’s effect on rice plant health is a critical environmental issue. This study reveals that rice plants absorb inorganic arsenic and dimethylarsenic differently, with dimethylarsenic posing a greater threat to rice plant health. These findings contribute to our understanding of arsenic toxicity in plants, highlighting the need for further research into detoxification strategies for dimethylarsenic.
Environmental context. Mine tailings are a mixture of fine materials obtained after crushing, processing and extracting the valuable minerals from ore. Ultramafic and mafic mine tailings have the potential to mineralise carbon, offering a solution to offset greenhouse gas emissions from the mining sector. The study revealed that the effects of wetting and drying ultramafic and mafic mine tailings under atmospheric conditions have the potential for carbon sequestration and acid mine drainage.
Environmental context. Environmental estrogens can disrupt the normal functioning of endocrine systems, and their occurrence in drinking water sources could cause potential health risk. We investigated concentrations of four estrogens in the lakes from the Taihu Basin, and found that BPA and EE2 were elevated in some sites. However, concentrations of all four environmental estrogens were below the national standards, and caused no health threat to local population.
Environmental context. Wildland fire smoke and its impacts on air quality and human health are increasing globally. However, uncertainties in organic emissions from these fires hinder our understanding of downwind atmospheric photochemical processes driving the formation of hazardous air pollutants. In this study, we investigated the impact of fuel moisture content on organic species emission during the combustion of ponderosa pine needles, an important fuel source in the western United States.
Environmental context. Arsenic (As) contamination in agricultural soil threatens safe agricultural production. Therefore, an ex situ magnet-assisted soil washing, using different types of nanoscale zerovalent iron was tested as a remediation option in soil restoration. Uncoated nanoparticles was the best tested option, with As removal at 45.5% and the nanoparticles were reusable up to four times.
Environmental context Organophosphorus (OP) is bioavailable to phytoplankton with photolysis can play an important role in the process. The photolysis behaviour of an OP (adenosine 5′-monophosphate, AMP) in seawater was investigated, and AMP can release inorganic phosphate under environmentally relevant light conditions, indicating OP photodegradation might be important in the phosphorus biogeochemical cycle. The results are helpful to further understand the bioavailability and cycle of OP in marine environment.
Environmental context Soil carbon sequestration plays an important role in achieving the goal of carbon neutrality. We studied the characteristics of organic carbon distribution and sequestration by stable carbon isotopes in nine types of soils in China and found that macro-aggregates possessed more organic carbon with a low degree of decomposition, while the overall direction of organic carbon transfer between aggregates was from macro-aggregates through micro-aggregates to the grain-size fractions of chalky clay. These results provide a foundation for understanding soil carbon sequestration in China’s cultivated lands.
Environmental context. The consumption of repurposed antibiotics increased due to the management of COVID-19, which in turn led to their increased presence in wastewater and potential environmental effects. This change has created a greater need for their analysis and treatment in different environmental water. This work presents a safe, low-cost method for analysing and treating water samples to ensure their suitability for human and animal use.
Environmental context. Natural dissolved organic matter strongly influences the biogeochemistry and bioavailability of trace metals in natural waters. Chemical equilibrium models are often used to predict the relative importance of the free metal cation, a recognised indicator of the metal’s bioavailability. Here we show how the nature of the organic matter varies between two lakes, affecting the measured speciation of copper and nickel, a result that challenges existing chemical equilibrium models.
This article belongs to the collection Dedication to Prof. Edward Tipping.
Environmental context. Decades of research tried to understand the inherent complexity of biodegradation of contaminants. We describe calculus of biodegradation driven by bioavailability, redox, geometry and acclimation (adaptation) of microbiota. We tested predictions for thousands of contaminants across wastewater treatment plants, explaining up to 70% of the variance in observations. This competes with more intensive methods, and enables more efficient monitoring, experimentation and data interpretation.
Environmental context. It is useful to know the concentration of ‘labile’, or chemically active, metal in soils because it can be used to predict metal solubility and environmental impact. Several methods for extracting the labile metal from soils have been proposed, and here we have tested two of these to see how well the resulting data can be used to model metal solubility. Such mixed approaches can be applied to different soil types with the potential to model metal solubility over large areas.
This article belongs to the collection Dedication to Prof. Edward Tipping.
Environmental context. The process of ethylene ozonolysis is an essential source of CH2OO radicals, and the latter is an important oxidant for the atmospheric pollutant SO2. The accuracy of a widely used atmospheric chemistry model (Master Chemical Mechanism, MCM) in quantifying SO2 oxidation has not been evaluated. In this study, this accuracy was evaluated, and optimal parameters underpinned by data from smog chamber experiments.
Environmental context. Everyone is familiar with the earth odour that comes from digging in the soil. We measured the chemicals comprising this odour and studied how the environment influences how much of these chemicals are released from disturbed soils. Understanding what conditions affect emission of these compounds from soils could provide new technologies for remotely assessing soil health and what people are doing to soils.
Environmental context. Organic matter (OM) biodegradation plays a key role as it is one of the main processes causing changes in the amount, composition and properties of OM in sediment. However, a complete understanding of its processes and mechanisms is still not reached. In this study, we aim to explore the chemical composition changes during biodegradation and identify underlying processes.
Environmental context. 
Rare earth elements (REEs) are technologically critical elements released into the environment by various anthropogenic activities, and whose ecotoxicological impacts are still largely unknown. REE binding to natural organic matter (NOM) is key to understand their fate and bioavailability in the environment. With this work, it is now possible to predict REE binding to NOM in various environments using various speciation software (ECOSAT, ORCHESTRA, Visual MINTEQ).
This article belongs to the collection Dedication to Prof. Edward Tipping.
Environmental context. Pesticides and other contaminants released by agricultural activities negatively impact aquatic biota and water quality, but are not always measured. The Polar Organic Chemical Integrative Sampler (POCIS) is among the most suitable tools for identifying pesticides and other organic compounds in water bodies. However, determination of a mean concentration (over the duration of the deployment) is still a significant challenge, which is addressed in the present work using field observations and a computational model.
Environmental context. Metal concentrations can build up to potentially harmful levels in marine mammals as they are at the top of the food chain. This review summarises the information available on metal concentrations in marine mammals, birds and turtles from around Australia. Despite large data gaps, the available data suggest that metal concentrations are similar to those encountered in other regions of the world.
Environmental context. Freshwater phytoplankton are involved in the biogeochemical cycling of arsenic within aquatic ecosystems via uptake processes. Rather than determining the mean arsenic content in a population of freshwater phytoplankton, we investigate the heterogeneity of arsenic uptake by single-cell ICP-MS. Our data show that arsenic distribution within a cell population may be highly heterogeneous, measured at the femtogram per cell level, and are affected by species and salinity.
Environmental context. Iron-containing combustion particles are likely to contribute to environmental iron deposition, while atmospheric acidic processing of such particles can promote their dissolution. Here we report the surface-mediated dissolution of iron from ashes generated by biomass burning power plants and kilns. Examination of the dissolution process at several environmentally relevant pHs, suggests that pH has little impact on the fraction of bioavailable Fe(II) that dissolves into the aqueous phase, although Fe(III) is heavily pH dependent.
Environmental context. Ammonia emissions from inorganic nitrogen fertilisers used in agriculture can impact air quality, human health and ecology. This study quantifies such emissions and their controlling factors from UK and Ireland agricultural soils. Emissions are variable and, from non-urea fertilisers, substantially exceed maximum emission factors used by the UK Department for Environment, Food and Rural Affairs. This suggests that UK emission factors need to be refined further, with consideration of inter alia land-use, fertiliser type, soil pH and chemical inhibitors.
This article belongs to the collection Dedication to Prof. Edward Tipping.
Environmental context. Elemental selenium plays an important role in maintaining human health and the growth of plants and animals. We studied the availability of selenium in soils and agricultural crops in Guiyang City, China, and found that the soil is selenium-rich and the crops are selenium-enriched. These results can help to understand and improve the development of mountain agriculture and rural revitalisation.
Environmental context. Naturally occurring arsenic was the likely cause of endemic black foot disease in groundwaters in Taiwan, and levels still exceed Taiwan EPA water quality standards. A method for the clean-up of these groundwaters that is both feasible and environmentally friendly is urgently needed. Oxidation of As(III) as H3AsO3 to the less toxic As(V)− and removal of As in groundwater was performed quantitatively by electrosorption using materials derived from agricultural wastes; this shows that this method has the potential to be a novel, green remediation method.
Environmental context. Mosses and lichens are widely distributed in montane forests and their important role in global biogeochemical cycles has been increasingly recognised. This study of mercury accumulation and sources in mosses and lichens, using mercury isotopic data, provides evidence that they promote atmospheric mercury deposition in these forests, which is an important function that should be incorporated into current mercury mass balance budgets for forests.
Environmental context. With the rapid pace of industrialisation and urbanisation, soil contamination by organic pollutants has become a global focus of concern due to its serious threat to ecosystems and human health. Although a myriad of synthetic catalysts have been developed, natural minerals have the potential to be developed into cost-effective, environmentally benign and efficient catalysts to decontaminate soil. The efficient performance of natural minerals demonstrated in this study indicates a potential for their utilisation in the removal of refractory organic pollutants in soil.