51,334 research outputs found

    Bentonite homogenisation and swelling: The effect of salinity

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    Hazardous radioactive waste must be removed from the biosphere, and geological storage is the universally favoured option for accomplishing this. In many cases, the repository designs include a clay buffer as part of the engineered barrier system (EBS) that surrounds the individual waste canisters and seals the disposal galleries. The emplacement of the EBS around the waste will generate small void spaces that must be closed to ensure that high permeability pathways do not develop. Many of the groundwaters at proposed disposal sites are saline, and this porewater chemistry, combined with the presence of technological voids may present a technical challenge to repository designers. In this study, a suite of experiments was conducted to examine the impact of fluid salinity in combination with the presence of a void space on the swelling behaviour of barrier bentonites. Both sodium and calcium bentonites were studied and the sample lengths were varied to provide an understanding of the role of axial strain on the homogenisation and swelling pressure development in the bentonite. After 100 days of testing the clay had swelled into the void space and differential swelling pressures (difference between the maximum and minimum swelling pressure recorded at a given time) had reduced substantially, highlighting the ability of the bentonite to expand into a void. However, clay that swelled into the void never generated significant swelling pressures during the testing period and differential pressures were still significant at the end of the tests. The calcium bentonite demonstrated much smaller peak swelling pressures than the sodium bentonite under the same salinity conditions, and in all tests, the generation of significant swelling pressure in the clay in the low-density end of the sample did not occur during the testing period. These findings suggest that the suppression of clay swelling at higher salinities is likely to strongly impact the void-filling process

    Diesel−biodegradation and biosurfactant−production by Janthinobacterium lividum AQ5-29 and Pseudomonas fildesensis AQ5-41 isolated from Antarctic soil

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    Given the substantial diesel demand in Antarctic operations, the means of addressing ecological restoration following its inappropriate release are attracting attention from researchers. The Madrid Protocol mandates the use of indigenous microbes in bioremediation. Recent studies have proposed many native isolates with biodegradation temperatures exceeding 20 °C, which are impractical for Antarctic contexts. Therefore, harnessing psychrophilic, native degraders with biosurfactant−producing traits presents an advantage for implementation in the harsh Antarctic environment. In this study, effective consortia/isolates demonstrated robust growth and biodegradation rates at 10 °C with diesel as the sole carbon source. Two primary bacterial members, Janthinobacterium lividum and Pseudomonas fildesensis, were identified from the most effective consortium SI 20 using 16S rRNA and multilocus−sequence−analysis (MLSA) clustering. The degraders were characterised as being psychrophilic, Gram-negative, rod−shaped, and catalase− and oxidase−positive. Despite the observed antagonistic effects during co-cultivation, strains J. lividum AQ5-29 and P. fildesensis AQ5-41 demonstrated effective diesel removal (2.91 & 4.20 mg mL−1) with biodegradation of C10 to C30 hydrocarbons (40−100%) at 10 °C in less than 8 days. Both strains also were identified as biosurfactant producers with varying emulsification activities (32−92%) and cell surface hydrophobicity (52−58%). These findings highlight the potential of both strains for restoring diesel-related substrates, particularly in Antarctica

    The genome sequence of the marbled white spot, Protodeltote pygarga (Hufnagel, 1766)

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    We present a genome assembly from an individual male Protodeltote pygarga (the Marbled White Spot; Arthropoda; Insecta; Lepidoptera; Noctuidae). The genome sequence is 421.1 megabases in span. Most of the assembly is scaffolded into 31 chromosomal pseudomolecules, including the Z sex chromosome. The mitochondrial genome has also been assembled and is 15.48 kilobases in length. Gene annotation of this assembly on Ensembl identified 17,784 protein coding genes

    UK hydrological outlook - January 2024

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    The Hydrological Outlook provides an insight into future hydrological conditions across the UK. Specifically, it describes likely trajectories for river flows and groundwater levels on a monthly basis, with a particular focus on the next three months. Well established monitoring programmes provide the current status of both river flows and groundwater levels at many sites across the UK, and data from these programmes provide the starting point for the Outlook. A number of techniques are used to project forwards from the current state and results from these are used to produce a summary that includes a highlights map

    Hydrochar from dairy sludge as phosphorus fertiliser affects greenhouse gas emissions and maize yield

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    Dairy processing sludge is a phosphorus (P) rich waste with a high potential to replace mineral phosphorus fertiliser in crop production, with possible enhancement of greenhouse gas emissions to the environment. Hydrothermal carbonisation is a technology that transforms the sludge into a hydrochar. The objective of this study is examining P availability of two hydrochars produced from Danish and Irish dairy sludge and their influence on greenhouse gas emissions and maize yields. The trial assessed (i) Danish dairy sludge; (ii) hydrochar derived from Danish sludge; (iii) hydrochar made from Irish dairy sludge; (iv) mineral phosphorus fertiliser; and (v) control. Emissions of nitrous oxide and carbon dioxide, soil pH, mineral nitrogen contents and crop yields were measured. Treatment with Danish dairy sludge had significantly higher cumulative nitrous oxide emissions while the emissions from both hydrochars were not significantly different compared to mineral phosphorous fertiliser. Statistical modelling showed that temperature, soil nitrate content, interactions both between temperature and precipitation, and between soil moisture and precipitation were drivers for nitrous oxide emissions. There was no difference in emissions among all treatments when scaled for yield. Hydrochar may alleviate the enhanced nitrous oxide emissions in soil without constraining P availability and maize crop yields

    Citizen scientists filling knowledge gaps of phosphate pollution dynamics in rural areas

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    In situ monitoring is fundamental to manage eutrophication in rivers and streams. However, in recent decades, the frequency and spatial coverage of regulatory monitoring have often been reduced due to funding and infrastructure limitations. This reduction has made it impossible to provide adequate coverage for most water bodies. In this study, trained citizen scientists filled spatial and temporal gaps in agency monitoring across a major catchment in rural England. By integrating data from citizen scientists, regulatory agencies, and the local water company, it was possible to demonstrate the opportunities for hypothesis-based citizen scientist monitoring to identify continuous and event-driven sources of phosphate pollution. Local citizen scientists effectively covered important spatial gaps, investigating river conditions both upstream and downstream of suspected pollution point sources, improving the identification of their temporal dynamics. When combined with long-term monitoring data from regulatory agencies, it became possible to identify areas within the catchment that exhibited increased phosphate concentrations during periods of low river discharge (summer). Inter-annual trends and anomaly detection suggested that continuous pollution sources dominated over event-driven sources in many sub-basins, allowing for the prioritisation of mitigation actions. This study highlights the opportunity for citizen scientists to fill gaps in regulatory monitoring efforts and contribute to the improved management of eutrophication in rural catchments

    Spatial, temporal, and demographic variability in patagonian toothfish (Dissostichus eleginoides) spawning from twenty-five years of fishery data at South Georgia

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    Patagonian toothfish (Dissostichus eleginoides) are a commercially important species that support a longline fishery at the subantarctic island of South Georgia (CCAMLR Subarea 48.3). Understanding the life history of Patagonian toothfish is key to the successful management and sustainability of this fishery. Using catch data from the past 25-years, 1997 to 2021, we provide an updated assessment of the spatial, temporal, and demographic variability of Patagonian toothfish spawning at South Georgia. Our findings confirm that spawning occurs in the vicinity of the shelf-break of South Georgia, with significant spawning hotspots detected at Shag Rocks, midway along both the northern and southern shelf breaks, and at the eastern end of the island. The location of these hotspots were consistent over the 25-years examined. Based on data between 1997 and 2007, when fishing occurred routinely all around the island and at Shag Rocks, 40% of detected hotspot locations overlapped with regions where Benthic Closed Areas (BCAs) were established in 2008. With this, we can estimate that approximately 40% of spawning hotspots are located within, and already protected by, the existing network of BCAs. There was evidence that the timing of toothfish spawning exhibited bimodality at South Georgia with a peak in April being observed in the first two years of the time series. This peak fell outside the seasonally restricted fishing season for many subsequent years. These findings are discussed in the context of both historic, current, and possible future regulatory changes to this longline fishery

    The role of the soil microbiome in the colonisation of glacier forefields by Antarctic pearlwort (Colobanthus quitensis) under current and future climate change scenarios

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    Glacier retreat in cold regions exposes new terrain for plant colonization. However, the roles of soil microbiomes in plant establishment and performance on newly-exposed forefields have rarely been assessed. Here, we compared the survival of Antarctic pearlwort (Colobanthus quitensis) individuals grown for three years in sterilised and unsterilised soils at sites initially at 30 m, 100 m and 300 m from three retreating Maritime Antarctic glaciers. We also installed open top chambers (OTCs), which increased air temperatures by ∼1.8 °C and reduced soil water potential by ≤ 4 kPa, on one forefield to test the effects of warming on C. quitensis survival and the soil microbiome. The main driver of plant performance was distance from glacier fronts, with a 32 kPa reduction in soil water potential apparently explaining reduced plant survival at 300m compared with 30 m from glaciers. Soil sterilisation had few effects on plant survival at 30 m and 100 m, but reduced survival at 300 m, which was attributable to reductions in beneficial plant-microbial interactions. Effects of OTCs on plant survival were amplified with distance from glacier and sterilisation, with plants not surviving in chambered and sterilised soil at 300 m after three years. Soil bacterial functionality altered from a phototrophic community at 30 m to a more specialized chemoheterotrophic community at 100–300 m. Fungal ortholog groups showed transfer RNA and ribosome biogenesis to be enriched in soil at 30 m, with spliceosomes and messenger RNA synthesis being more frequent at 300 m. We propose that soil microbiomes improve the environmental tolerance of C. quitensis through enhanced physiological performance, which in turn improves survival and facilitates the species’ colonization of newly-exposed glacier forefield soils. These plant-microbe interactions are likely to become increasingly important as the climate of Maritime Antarctica changes over future decades

    Atmospheric Degradation of Ecologically Important Biogenic Volatiles:Investigating the Ozonolysis of (E)-β-Ocimene, Isomers of α and β-Farnesene, α-Terpinene and 6-Methyl-5-Hepten-2-One, and Their Gas-Phase Products

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    Biogenic volatile organic compounds (bVOCs), synthesised by plants, are important mediators of ecological interactions that can also undergo a series of reactions in the atmosphere. Ground-level ozone is a secondary pollutant generated through sunlight-driven reactions between nitrogen oxides (NOx) and VOCs. Its levels have increased since the industrial revolution and reactions involving ozone drive many chemical processes in the troposphere. While ozone precursors often originate in urban areas, winds may carry these hundreds of kilometres, causing ozone formation to also occur in less populated rural regions. Under elevated ozone conditions, ozonolysis of bVOCs can result in quantitative and qualitative changes in the gas phase, reducing the concentrations of certain bVOCs and resulting in the formation of other compounds. Such changes can result in disruption of bVOC-mediated behavioural or ecological interactions. Through a series of gas-phase experiments using Gas Chromatography Mass Spectrometry (GC-MS) and Proton Transfer Reaction Mass Spectrometry (PTR-MS), we investigated the products and their yields from the ozonolysis of a range of ubiquitous bVOCs, which were selected because of their importance in mediating ecological interactions such as pollinator and natural enemy attraction and plant-to-plant communication, namely: (E)-β-ocimene, isomers of α and β-farnesene, α-terpinene and 6-methyl-5-hepten-2-one. New products from the ozonolysis of these compounds were identified, and the formation of these compounds is consistent with terpene-ozone oxidation mechanisms. We present the degradation mechanism of our model bVOCs and identify their reaction products. We discuss the potential ecological implications of the degradation of each bVOC and of the formation of reaction products
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