Fuel cell stacks are growing: both in numbers deployed in the field but also in terms of active electrode areas. The pursuit of higher-power applications and power densities means that cell active areas upwards of 400cm² are now commonplace. With larger electrodes comes an increased risk of non-uniform distributions of current density, temperature and reactant concentrations, which may lead in turn to locally-accelerated degradation and premature failure. Whilst detailed CFD/FEA modelling and simulation can help to refine designs, direct observations via in-situ and in-operando measurements are vital to verify model outputs and identify complex phenomena that models can fail to capture. Our group has developed three spatially-resolved diagnostic techniques along with instrumentation, measurement systems and software tools designed to make their application as straightforward as possible for the characterisation of large-format PEMFC MEAs. Spatially-resolved electrochemical impedance spectroscopy (SR-EIS) has been demonstrated using a commercially-available, segmented current sensor plate. A new software tool integrates a multiplexer for automated SR-EIS measurements, along with automatic equivalent circuit fitting and visualisation of spatially-resolved Ohmic, charge transfer and mass transport-related losses. A novel technique has been developed for the measurement of distributed electrochemical surface area (dECSA), allowing localised changes in ECSA resulting from non-uniform ageing to be determined for the first time. Finally, a chronoamperometric sensor array is demonstrated for the spatially-resolved measurement of in-plane oxygen concentration at the PEMFC cathode. In combination, these characterisation techniques offer a significant advance in PEMFC diagnostics, providing a deeper insight into non-uniform conditions and degradation in large-format PEMFCs.

Migratory species face geographically dispersed pressures over the course of their annual cycles. Designing effective conservation strategies for these species requires a detailed understanding of how these different pressures affect demographic rates throughout the annual cycle. As a long-lived species, population trends in the rapidly declining Eurasian curlew Numenius arquata are likely to be highly sensitive to impacts on adult survival. We combine data from multiple sources to analyse survival rates of overlapping populations that breed and/or winter in the United Kingdom. Our analyses demonstrate that curlew survival rates are reduced by cold weather and at high density; however, overall survival rates are high and have increased in recent years. Current population declines are, therefore, likely to be driven by low productivity. As such, efforts to stabilise and reverse declines should focus on increasing breeding success from current estimated levels of 0.25 chicks nest−1 to 0.43 chicks nest−1. In addition to increasing productivity, effective conservation strategies will need to maintain high levels of survival, which requires an improved understanding of population connectivity and demographic variation throughout the annual cycle.

HPLC-ICP-MS utilising a ZirChrom (R)-SAX column with an aqueous 10 mM ammonium dihydrogen phosphate mobile phase at pH 7.5 (adjusted with aqueous ammonia) was evaluated for measuring glycerol arsenoriboside (OH-ribose), phosphate arsenoriboside (PO4-ribose), sulfonate arsenoriboside (SO3-ribose) and sulfate arsenoriboside (OSO3-ribose) in marine macroalgae and animals by analysis of seven reference materials. The results obtained were compared to those obtained using PRP-X100 anion-exchange chromatography. Inorganic arsenic species were not eluted from the zirconium column due to the strong interaction with the zirconia stationary phase. Measurements of SO3-ribose and OSO3-ribose concentrations were in close agreement with those obtained using the PRP-X100 column with a 0.005 mg As kg(-1) detection limit. Peak shapes of these arsenoriboses were improved allowing lower amounts to be quantified. The quantification of OH-ribose and PO4-ribose, however, was sample dependent and not possible if arsenobetaine (AB) and (DMA) were present at large concentrations in samples because of coelution of these species with OH-ribose and PO4-ribose, respectively. In the absence of OH-ribose, AB can be determined using the zirconium column while AB on the PRP-X100 column coelutes with arsenic cations.

Ferrosilicon 75, a 50:50 mixture of silicon and iron disilicide, has been activated toward hydrogen generation by processing using ball milling, allowing a much lower concentration of sodium hydroxide (2 wt %) to be used to generate hydrogen from the silicon in ferrosilicon with a shorter induction time than has been reported previously. An activation energy of 62 kJ/mol was determined for the reaction of ball-milled ferrosilicon powder with sodium hydroxide solution, which is around 30 kJ/mol lower than that previously reported for unmilled ferrosilicon. A series of composite powders were also prepared by ball milling ferrosilicon with various additives in order to improve the hydrogen generation properties from ferrosilicon 75 and attempt to activate the silicon in the passivating FeSi2 component. Three different classes of additives were employed: salts, polymers and sugars. The effects of these additives on hydrogen generation from the reaction of ferrosilicon with 2 wt% aqueous sodium hydroxide were investigated. It was found that composites formed of ferrosilicon and sodium chloride, potassium chloride, sodium polyacrylate, sodium polystyrene sulfonate-co-maleic acid or fructose showed reduced induction times for hydrogen generation compared to that observed for ferrosilicon alone, and all but fructose also led to an increase in the maximum hydrogen generation rate. In light of its low cost and toxicity and beneficial effects, sodium chloride is considered to be the most effective of these additives for activating the silicon in ferrosilicon toward hydrogen generation. Materials characterisation showed that neither ball milling on its own nor use of additives was successful in activating the FeSi2 component of ferrosilicon for hydrogen generation and the improvement in rate and shortening of the induction period was attributed to the silicon component of the mixture alone The gravimetric storage capacity for hydrogen in ferrosilicon 75 is therefore maintained at only 3.5% rather than the 10.5% ideally expected for a material containing 75% silicon. In light of these results, ferrosilicon 75 does not appear a good candidate for hydrogen production in portable applications. (C) 2018 The Authors. Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.

Be isotopes are a useful tracer of sediment source and transport pathways but have not been widely tested in glacio-marine environments. We measured Be isotopes in a range of depositional environments from open marine, sub-ice shelf and subglacial settings throughout Prydz Bay, one of Antarctica's largest ice drainage systems. We find that strong sub-ice shelf and bottom current circulations can advect 10Be-rich open marine sediments into an ice shelf cavity, and 10Be-poor terrestrial sediments onto the continental shelf at the ice shelf outflow, meaning that 10Be concentrations reflect sub-ice shelf circulation patterns rather than depositional environment. However, HCl-extractable 10Be/9Be ratios can provide a more robust discrimination of sediment deposited in open marine and sub-ice shelf settings. Thus, Be isotopes are a useful tracer of both environmental setting and sub-ice shelf circulation strength in both modern and paleo-ice sheet margins.

The influence of the air cooling flow rate and current density on the temperature, voltage and power density is a challenging issue for air-cooled, open cathode fuel cells. Electro-thermal maps have been generated using large datasets (530 experimental points) to characterise these correlations, which reveal that the amount of cooling, alongside with the load, directly affect the cell temperature. This work uses the design of experiment (DoE) approach to tackle two challenges. Firstly, an S-optimal design plan is used to reduce the number of experiments from 530 to 555 to determine the peak power density in an electro-thermal map. Secondly, the design of experiment approach is used to determine the fastest way to reach the highest power density, yet limiting acute temperature gradients, via three intermediate steps of current density and air cooling rate.

Environmental contextKnowledge of the pathways by which arsenic is accumulated and transferred in marine ecosystems is scarce. Molluscs are important keystone organisms providing a link between primary producers (micro and macroalgae) and higher trophic levels such as fish. The present study examines the accumulation and species of arsenic in common bivalve molluscs from south-east Australia to understand the cycling of arsenic in marine food webs. AbstractThe present paper reports the whole-tissue total arsenic concentrations and water-soluble arsenic species in 12 common coastal Australian bivalve mollusc species. Mean arsenic concentrations ranged from 18 to 57 mu gg(-1) dry mass. Planktivores had significantly less arsenic (20-40 mu gg(-1); 22 +/- 3 mu gg(-1)) than did suspension and deposit feeders (36-57 mu gg(-1); 43 +/- 7 mu gg(-1)), with those associated with fine clay-silt sediments (49 +/- 7 mu gg(-1)) having significantly more arsenic than those associated with sand substrates (31 +/- 11 mu gg(-1) ). Most planktivores and suspension feeders had similar arsenic species, with high proportions of arsenobetaine (AB) (64-92%) and relatively low proportions of other arsenic species (0.55-15.8%). Lower proportions of AB (13-57%) and larger proportions of inorganic arsenic (6-7%) were found in deposit feeders, reflecting increased exposure to inorganic arsenic in sediments. The study indicated that at lower trophic levels, organisms feed on algae and suspended matter containing a range of arsenic species including arsenosugars and AB. The implications for arsenic cycling are that as all bivalve molluscs accumulate AB and are a source of AB in benthic food webs. Because all bivalve molluscs also contained appreciable concentrations of arsenoriboses, precursors are present for the de novo synthesis of AB. As well, deposit feeders have higher proportions of inorganic arsenic that can be metabolised to different end products when ingested by higher trophic organisms

Mercury (Hg) is a toxic element and has no known biological functions in humans. This study measured total Hg and methyl mercury (MeHg) concentrations in commonly consumed fish and seafood as well as to estimate the risk of Hg contamination through seafood consumption by Malaysians. The concentrations of total Hg and MeHg in 8 species of crustaceans (n = 15), 5 species of cephalopods (n = 12), and 29 species of fish (n = 78) from West Peninsular Malaysia are reported. Total mercury concentrations in crustaceans, cephalopods and fish were 0.033 +/- 0.033 mu g/g, 0.040 +/- 0.025 mu g/g and 0.106 +/- 0.128 mu g/g wet weight respectively. The proportion of methyl mercury in fish was 81-99% with a mean of 93 +/- 5% (n = 15). Significantly higher mercury concentrations were observed in demersal fish, fish on higher trophic level and fish with body length of > 20 cm. All fish and seafood were below the Malaysian Food Regulations of 0.5 mu g/g wet weight mercury for fish and fishery products and 1.0 mu g/g wet weight mercury for predatory fish. The consumption of fish from certain seafood species, however, should be taken into consideration to ensure that the Provisional Tolerable Weekly Intake (PTWI) of MeHg does not exceed 1.6 mu g/kg body weight/week.

A variety of approaches for measuring the content and speciation of Sb in environmental matrices are discussed.

Environmental contextIn countries where inhabitants are not exposed to arsenic-contaminated drinking water, food is the major source of potentially toxic inorganic arsenic. To complement the existing worldwide dataset on arsenic in rice, data are presented on Australian- and overseas-grown rice, and assessed in terms of possible risk. Only a diet comprising multiple serves of some rice products per day poses a potential risk to young children. AbstractArsenic concentrations and speciation measurements were determined for six varieties of Australian-grown rice (n = 130), imported rice (n = 53) and rice products (n = 56) from supermarkets. Total As, inorganic As and dimethylarsinic acid (DMA) concentrations in Australian rice ranged from 16 to 630 µg As kg−1 (mean ± s.d.: 220 ± 122 µg kg−1), 16 to 250 µg As kg−1 (92 ± 52 µg As kg−1) and <5 to 432 µg As kg−1 (125 ± 109 µg As kg−1), respectively. Total As, inorganic As and DMA concentrations in imported rice ranged between 31 and 376 µg As kg−1 (130 ± 98 µg kg−1), 17 and 198 µg As kg−1 (73 ± 40 µg As kg−1) and <5 and 327 µg As kg−1 (84 ± 92 µg As kg−1) respectively. Few samples exceeded the guidelines for inorganic As in polished rice. In rice products, total As, inorganic As and DMA concentrations ranged between 21 and 480 µg As kg−1 (160 ± 110 µg As kg−1), 20 and 255 µg As kg−1 (92 ± 78 µg As kg−1) and <5 and 340 µg As kg−1 (65 ± 69 µg As kg−1) respectively. Sixteen samples exceeded the 100 µg kg−1 maximum for inorganic As concentration in rice foods for infants and young children. Ingestion of multiple serves of some rice products poses a potential risk. Environmental chemistry gaps, on processes influencing As occurrence in rice, are discussed.

For the first time, the process of hydrogen evolution from ferrosilicon 75 using sodium hydroxide solution has been investigated as a function of temperature using a combination of X-ray photoelectron spectroscopy, X-ray diffraction and physical measurements. Ferrosilicon 75, a mixture of silicon (50wt.%) and iron disilicide (50wt.%), has been shown to produce hydrogen by the action of sodium hydroxide solution on the silicon only, with the iron disilicide acting in the role of spectator/protector species for the silicon. Neither iron disilicide alone nor ferrosilicon 45, which does not contain a pure metallic silicon phase, was found to generate hydrogen under similar reaction conditions, further indicating that the presence of a pure metallic silicon phase is essential for hydrogen generation. As the iron disilicide acts as a diluent for the active silicon, it is hypothesized that this would result in a slower release of hydrogen than that which would be obtained from the reaction of silicon alone, which may be useful for applications which require a long-term, sustained release of hydrogen. A hydrogen yield of 462.5mL/g and a maximum hydrogen generation rate of 83mL/ming were obtained within 10min of reaction with 40wt.% NaOH at 348K. (c) 2017 The Authors. International Journal of Energy Research Published by John Wiley & Sons Ltd.

Agricultural practices, if not managed correctly, can have a negative impact on receiving environments via waste disposal and discharge. In this study, a chicken slaughter facility on the rural outskirts of Sydney, Australia, has been identified as a possible source of persistent effluent discharge into a peri-urban catchment. Questions surrounding the facility's environmental management practices go back more than four decades. Despite there having never been a definitive determination of the facility's impact on local stream water quality, the New South Wales Environment Protection Authority (NSW EPA) has implemented numerous pollution reduction requirements to manage noise and water pollution at the slaughter facility. However, assessment of compliance remains complicated by potential additional sources of pollution in the catchment. To unravel this long-standing conundrum related to water pollution we apply a forensic, multiple lines of evidence approach to delineate the origin of the likely pollution source(s). Water samples collected between 2014 and 2016 from irrigation pipes and a watercourse exiting the slaughter facility had elevated concentrations of ammonia (max: 63,000 µg/L), nitrogen (max: 67,000 µg/L) and phosphorus (max: 39,000 µg/L), which were significantly higher than samples from adjacent streams that did not receive direct runoff from the facility. Arsenic, sometimes utilised in growth promoting compounds, was detected in water discharging from the facility up to ~4 times (max 3.84 µg/L) local background values (<0.5 µg/L), with inorganic As(∑V+III) being the dominant species. The spatial association of elevated water pollution to the facility could not unequivocally distinguish a source and consequently DNA analysis of a suspected pollution discharge event was undertaken. Analysis of catchment runoff from several local streams showed that only water sampled at the downstream boundary of the facility tested positive for chicken DNA, with traces of duck DNA being absent, which was a potential confounder given that wild ducks are present in the area. Further, PCR analysis showed that only the discharge water emanating from the slaughter facility tested positive for a generalized marker of anthropogenic pollution, the clinical class 1 integron-integrase gene. The environmental data collected over a three-year period demonstrates that the slaughter facility is indisputably the primary source of water-borne pollution in the catchment. Moreover, application of DNA and PCR for confirming pollution sources demonstrates its potential for application by regulators in fingerprinting pollution sources.

The use of sub-critical water and hydrogen peroxide provides a fast, clean and efficient means of extracting arsenic from rice.

Recently developed analytical techniques allowed for the detection of a range of dissolved arsenic-sulphur species in sulphur-rich environments. These so called thioarsenates are unstable, however, and can degrade upon handling and storage. An experiment evaluating the effect of exposure to air on arsenic and sulphur-enriched geothermal waters demonstrated a near to complete loss of thioarsenate species to arsenite or arsenate during short oxidation times. In contrast, thioarsenic standards were stable for the duration of analysis in spite of exposure to air. For samples containing thio-methylated arsenic species, the extent of oxidation varied for different methylated arsenic species. This study recommends flash freezing of samples in liquid nitrogen immediately after recovery and further storage under anaerobic conditions at −80°C. A second experiment to test the efficiencies of different HPLC columns for separating arsenic species resulted in the preference for an IonPac column with NaOH as the mobile phase when analysing arsenic thioanions, over the commonly used PEEK PRP-X100 anion exchange and Atlantis C18 reverse phase column with ammonium phosphate mobile phases. Distinct separation of thio-methylated arsenic species with the IonPac column, however, was not successful potentially due to matrix components. Acceptable detection, separation and quantification of thio-methylated arsenic species were only achieved with the Atlantis C18 column. This study shows that preservation and analysis of samples is matrix dependent, which holds important implications for efforts to interpret arsenic speciation in geothermal waters, especially those of low pH (2–3), low oxygen (≤49% saturation), low iron (≤5mgL−1) and high sulphur concentrations (≥91mgL−1).

The contamination of cereals with arsenic (As) is a global health and agronomic concern. This study compared the physiological response, As uptake and As speciation in the grains and above ground tissues of 20 wheat cultivars exposed to 5 mg As kg(-1) soil as either arsenate (Asy) or dimethylarsenate (DMA) under glasshouse conditions.Germination rates for the majority of cultivars exceeded 80% for the majority of cultivars when exposed to Asy, but fell significantly to 20-40% when exposed to DMA. For a number of cultivars, grain yields were 20-50% lower when plants were exposed to DMA compared to Asy.Grain As concentrations were between 0.6 and 1.6 mu g As g(-1) grain across the twenty cultivars when exposed to As-v, whereas grain As concentrations were much higher (2.2-4.6 mu g As g(-1) grain) when exposed to DMA. When plants were exposed to As-v, 100% of the As present in the grain was found as inorganic As while in plants exposed to DMA, 70-90% of As was present as DMA with the remainder found as inorganic As. DMA is believed to be incorporated by plants via silica (Si) acid channels and assessment of grain Si concentrations demonstrated that up to 40% less Si was accumulated in grains when plants were exposed to DMA. The decreased germination rates and grain yields in the presence of DMA is similar to the symptoms described for straight head disease in rice, which has been linked to DMA exposure.The results presented here indicate some analogous processes occur in wheat to those described in rice. We hypothesise that exposure to DMA may have inhibited Si-metabolism and translocation which resulted in both developmental impairment and possibly an increased susceptibility to soil pathogens. (C) 2017 Elsevier Ltd. All rights reserved.