Perspectives on using peat records to reconstruct past atmospheric Hg levels.

Anthropogenic mercury (Hg) emissions to the atmosphere have increased the concentration of this potent neurotoxin in terrestrial and aquatic ecosystems. The magnitude of regional variation in atmospheric Hg pollution levels raises questions about the interactions between natural processes and human activities at local and regional scales that are shaping global atmospheric Hg cycling. Peatlands are potentially valuable and widespread records of past atmospheric Hg levels that could help address these questions.

Microbiota-dependent in vivo biotransformation, accumulation, and excretion of arsenic from arsenobetaine-rich diet.

Arsenobetaine (AB), a major organic arsenic (As) species in seafood, is regarded as safe by current regulatory assessments due to low toxicity and rapid unmodified urinary excretion. This notion has been challenged by reports of AB metabolism by intestinal bacteria in vitro and more recent evidence of in vivo AB metabolism in mice. However, these studies did not establish the causal role of intestinal bacteria in AB transformation in vivo.

Marine and terrestrial contributions to atmospheric deposition fluxes of methylated arsenic species.

Arsenic, a toxic element from both anthropogenic and natural sources, reaches surface environments through atmospheric cycling and dry and wet deposition. Biomethylation volatilizes arsenic into the atmosphere and deposition cycles it back to the surface, affecting soil-plant systems. Chemical speciation of deposited arsenic is important for understanding further processing in soils and bioavailability.

Root-exuded specialized metabolites reduce arsenic toxicity in maize.

By releasing specialized metabolites, plants modify their environment. Whether and how specialized metabolites protect plants against toxic levels of trace elements is not well understood. We evaluated whether benzoxazinoids, which are released into the soil by major cereals, can confer protection against arsenic toxicity.

Plant secondary metabolite-dependent plant-soil feedbacks can improve crop yield in the field.

Plant secondary metabolites that are released into the rhizosphere alter biotic and abiotic soil properties, which in turn affect the performance of other plants. How this type of plant-soil feedback affects agricultural productivity and food quality in the field in the context of crop rotations is unknown. Here, we assessed the performance, yield and food quality of three winter wheat varieties growing in field plots whose soils had been conditioned by either wild type or benzoxazinoid-deficient maize mutant plants.

Soil (microbial) disturbance affect the zinc isotope biogeochemistry but has little effect on plant zinc uptake.

Zinc (Zn) is an important micronutrient but can be toxic at elevated concentrations. We conducted an experiment to test the effect of plant growth and soil microbial disturbance on Zn in soil and plants. Pots were prepared with and without maize and in an undisturbed soil, a soil that was disturbed by X-ray sterilization and a soil that was sterilized but reconditioned with the original microbiome.

Organo-mercury species in a polluted agricultural flood plain: Combining speciation methods and polymerase chain reaction to investigate pathways of contamination.

The analysis of organic mercury (Hg) species in polluted soils is a necessary tool to assess the environmental risk(s) of mercury in contaminated legacy sites. The artificial formation of monomethylmercury (MeHg) during soil extraction and/or analysis is a well-known limitation and is especially relevant in highly polluted areas where MeHg/Hg ratios are notoriously low. Although this has been known for almost 30 years, the thorough characterisation of artificial formation rates is rarely a part of the method development in scientific literature.

Increasing temperature and flooding enhance arsenic release and biotransformations in Swiss soils.

Reductive dissolution is one of the main causes for arsenic (As) mobilisation in flooded soils while biomethylation and biovolatilisation are two microbial mechanisms that greatly influence the mobility and toxicity of As. Climate change results in more extreme weather events such as flooding and higher temperatures, potentially leading to an increase in As release and biotransformations. Here, we investigated the effects of flooding and temperature on As release, biomethylation and biovolatilisation from As-rich soils with different pH and source of As (one acidic and anthropogenic (Salanfe) and one neutral and geogenic (Liesberg)).

Soil chemistry determines whether defensive plant secondary metabolites promote or suppress herbivore growth.

Plant secondary (or specialized) metabolites mediate important interactions in both the rhizosphere and the phyllosphere. If and how such compartmentalized functions interact to determine plant-environment interactions is not well understood. Here, we investigated how the dual role of maize benzoxazinoids as leaf defenses and root siderophores shapes the interaction between maize and a major global insect pest, the fall armyworm.

Validation and deployment of a quantitative trapping method to measure volatile antimony emissions.

Microbial-mediated Sb volatilization is a poorly understood part of the Sb biogeochemical cycle. This is mostly due to a lack of laboratory and field-deployable methods that are capable of quantifying low-level emissions of Sb from diffuse sources. In this study, we validated two methods using a HO -HNO liquid chemotrap and an activated coconut shell charcoal solid-phase trap, achieving an absolute limit of detection of 4.

A Systematic Analysis of Metal and Metalloid Concentrations in Eight Zebrafish Recirculating Water Systems.

Metals and metalloids are integral to biological processes and play key roles in physiology and metabolism. Nonetheless, overexposure to some metals or lack of others can lead to serious health consequences. In this study, eight zebrafish facilities collaborated to generate a multielement analysis of their centralized recirculating water systems.

250-year records of mercury and trace element deposition in two lakes from Cajas National Park, SW Ecuadorian Andes.

Historical records of trace elements in lake sediments provide source-to-sink information about potentially toxic pollutants across space and time. We investigated two lakes located at different elevations in the Ecuadorian Andes to understand how trace element fluxes are related to (i) geology, (ii) erosion in the watersheds, and (iii) local point sources and atmospheric loads. In remote Lake Fondococha (4150 m a.

Arsenic dynamics in paddy soil under traditional manuring practices in Bangladesh.

Fertilization with organic matter (farm yard manure and/or rice straw) is thought to enhance arsenic (As) mobilization into soil porewaters, with subsequent As assimilation by rice roots leading to enhanced translocation to the grain. Here, interlinked experiments (field manuring and soil batch culture) were conducted to find the effect of organic matter at a field application rate practiced in Bangladesh (5 t/ha) on As mobilization in soil for paddies impacted by As contaminated groundwater irrigation, a widespread phenomenon in Bangladesh where the experiments were conducted. Total As concentration in a paddy soil (Sonargaon) ranged from 21.

Variability in Arsenic Methylation Efficiency across Aerobic and Anaerobic Microorganisms.

Microbially-mediated methylation of arsenic (As) plays an important role in the As biogeochemical cycle, particularly in rice paddy soils where methylated As, generated microbially, is translocated into rice grains. The presence of the arsenite (As(III)) methyltransferase gene () in soil microbes has been used as an indication of their capacity for As methylation. Here, we evaluate the ability of seven microorganisms encoding active ArsM enzymes to methylate As.

Emerging investigator series: mercury mobility and methylmercury formation in a contaminated agricultural flood plain: influence of flooding and manure addition.

The fate and the methylation of mercury (Hg) in the terrestrial environment are still poorly understood and although the main drivers of release and methylation of mercury in soils are known (low redox potential and microbial carbon availability) their interactions are not well understood. This is of concern since many agriculturally used floodplains, where the recurring flooding and agricultural practices (e.g.

Sorption kinetics of isotopically labelled divalent mercury (Hg) in soil.

Understanding the sorption kinetics of Hg is the key to predicting its reactivity in soils which is indispensable for environmental risk assessment. The temporal change in the solubility of Hg spikes (6 mg kg) added to a range of soils with different properties was investigated and modelled. The sorption of Hg displayed a biphasic pattern with a rapid initial (short-term) phase followed by a slower (time-dependent) one.

Uptake and Transformation of Methylated and Inorganic Antimony in Plants.

Used as a hardening agent in lead bullets, antimony (Sb) has become a major contaminant in shooting range soils of some countries including Switzerland. Soil contamination by Sb is also an environmental problem in countries with Sb-mining activities such as China and Bolivia. Because of its toxicity and relatively high mobility, there is concern over the risk of Sb transfer from contaminated soils into plants, and thus into the food chain.

A Herbivore Tag-and-Trace System Reveals Contact- and Density-Dependent Repellence of a Root Toxin.

Foraging behavior of root feeding organisms strongly affects plant-environment-interactions and ecosystem processes. However, the impact of plant chemistry on root herbivore movement in the soil is poorly understood. Here, we apply a simple technique to trace the movement of soil-dwelling insects in their habitats without disturbing or restricting their interactions with host plants.

Cadmium and lead in vegetable and fruit produce selected from specific regional areas of the UK.

Cadmium and lead were determined in fruit and vegetable produce (~1300 samples) collected from a field and market basket study of locally grown produce from the South-West of Britain (Devon and Cornwall). These were compared with similarly locally grown produce from the North-East of Britain (Aberdeenshire). The concentrations of cadmium and lead in the market basket produce were compared to the maximum levels (ML) set by the European Union (EU).

Identification and quantification of phytochelatins in roots of rice to long-term exposure: evidence of individual role on arsenic accumulation and translocation.

Rice has the predilection to take up arsenic in the form of methylated arsenic (o-As) and inorganic arsenic species (i-As). Plants defend themselves using i-As efflux systems and the production of phytochelatins (PCs) to complex i-As. Our study focused on the identification and quantification of phytochelatins by HPLC-ICP-MS/ESI-MS, relating them to the several variables linked to As exposure.

Biovolatilisation: a poorly studied pathway of the arsenic biogeochemical cycle.

It has been known for over a hundred years that microorganisms can produce volatile arsenic (As) species, termed "arsines". However, this topic has received relatively little attention compared to As behaviour in soils and biotransformation through the trophic level in the marine and terrestrial environment. We believe this is due to long-standing misconceptions regarding volatile As stability and transport as well as an absence, until recently, of appropriate sampling methods.

Arsenic speciation and localization in horticultural produce grown in a historically impacted mining region.

A field and market basket study (~1300 samples) of locally grown fruits and vegetables from historically mined regions of southwest (SW) England (Cornwall and Devon), and as reference, a market basket study of similarly locally grown produce from the northeast (NE) of Scotland (Aberdeenshire) was conducted to determine the concentration of total and inorganic arsenic present in produce from these two geogenically different areas of the U.K. On average 98.

Arsenic and selenium mobilisation from organic matter treated mine spoil with and without inorganic fertilisation.

Organic matter amendments are applied to contaminated soil to provide a better habitat for re-vegetation and remediation, and olive mill waste compost (OMWC) has been described as a promising material for this aim. We report here the results of an incubation experiment carried out in flooded conditions to study its influence in As and metal solubility in a trace elements contaminated soil. NPK fertilisation and especially organic amendment application resulted in increased As, Se and Cu concentrations in pore water.

HPLC-HG-ICP-MS: a sensitive and selective method for inorganic arsenic in seafood.

The addition of an online post-column hydride generation (HG) step to the commonly used high-performance liquid chromatography inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) setup for arsenic speciation proved to significantly improve the detection limits for the determination of inorganic arsenic (iAs) as arsenate in seafood samples, where the limit of detection and limit of quantification were found to be 0.0004 and 0.0014 mg kg(-1), respectively with HG.