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Resolving the syn-genetic mineralization age of a metamorphosed Archean VHMS deposit using multiple geochronological approaches
No full textAccurately determining the timing of mineralization is essential for exploring syn-genetic stratiform mineral systems, such as volcanic-hosted massive sulfide (VHMS) deposits. This study integrates multiple geochronological techniques to constrain both the age of syn-genetic mineralization and subsequent overprinting magmatic, metamorphic and deformation events at the King VHMS deposit, Western Australia. The timing of syn-genetic mineralization is collectively constrained by consistent ages from U–Pb zircon geochronology of host felsic volcanic rocks (2725 ± 10 Ma), a Re–Os pyrite isochron (2730 ± 26 Ma), and Pb–Pb galena model ages (ca. 2714–2718 Ma). Pyrrhotite, formed via metamorphic desulfidation of pyrite, records a younger Re–Os age of 2652 ± 32 Ma, overlapping with the timing of prograde metamorphism dated by in situ Lu–Hf garnet analysis at 2680 ± 28 Ma. A Re–Os age from massive sulfide ore (2664 ± 23 Ma), reflecting a mixture of pyrite and pyrrhotite, produces a geologically meaningless average due to metamorphic re-equilibration, highlighting limitations of bulk Re–Os dating in high-grade metamorphosed systems. Quartz monzonite intrusions that crosscut the deposit and are associated with the regional M2 metamorphism yielded weighted mean U–Pb zircon ages of ca. 2676–2665 Ma, and are associated with minor molybdenite mineralization (Re–Os ages ca. 2650–2655 Ma). Collectively, these results confirm that the King Zn deposit represents the first phase of VHMS mineralization during the formation of the Kalgoorlie-Kurnalpi Rift (KKR), and significantly predates other VHMS deposits of the Eastern Goldfields. This study also demonstrates that the Re–Os isotopic signature of syn-genetic pyrite can be retained through amphibolite-facies metamorphism, providing a new opportunity to directly date VHMS deposits affected by high-grade metamorphism in Archean cratons globally. In contrast, Re–Os ages of pyrrhotite record prograde metamorphism, offering a potential tool for constraining metal remobilization events
Increasing concentrations of polychlorinated biphenyls (PCBs) in Eurasian otters (Lutra lutra) from Wales suggest remobilisation from sediment sinks
Full text linkDespite ongoing regulatory efforts to mitigate PCB pollution, their presence remains pervasive in the environment, with concentrations in top predators still reaching toxicologically significant levels. To assess temporal and spatial variation of PCB concentrations in Wales between 2010 and 2019, we analysed liver samples of a sentinel predator, the Eurasian otter (Lutra lutra), for 23 PCB congeners. PCBs were detected in all livers analysed, with PCB 153 recording the highest individual concentration (545.8 ug/kg wet weight); sixteen percent of otters had concentrations above a toxic threshold for dioxin-like PCBs. Statistical modelling revealed a negative correlation between concentrations of dioxin-like PCBs and otter body condition. While previous studies on otters from the UK showed declining PCB concentrations between 1983 and 2009, our model predictions indicated a significant increase between 2010 and 2019, mirroring trends seen in marine mammals. Higher concentrations were observed in otters from coastal, low-altitude areas. A multi-model inference approach was used to identify the best groups of predictors for each congener, suggesting that remobilisation of PCBs from riverine and coastal sediment sinks is now a major driver of PCB concentrations, with the impacts of climate change likely exacerbating remobilisation. While PCB concentrations are often below limits of detection in water, and below the current Water Framework Directive Environmental Quality Standard in fish, they remained at toxicologically relevant levels in otters from Wales. Our findings underscore the importance of biomonitoring across trophic levels, and suggest that current environmental quality standards for water and fish are not protective of top predators. Addressing environmental PCB contamination will require strengthened international efforts both to manage the significant sinks of legacy pollutants, as well as to meet climate change mitigation targets
Talking About the Weather: The Feasibility of Using Very High-Resolution Optical Satellite Imagery to Monitor Live and Stranded Cetaceans Around the UK and UK Overseas Territories
Full text linkMonitoring live and stranded cetaceans can be expensive and logistically challenging, resulting in knowledge gaps. Very high-resolution (VHR) optical satellites are considered a potential solution to addressing some of these gaps. Despite success at detecting live and stranded cetaceans, satellites have only been trialed on restricted spatiotemporal scales. This project presents a framework for assessing the feasibility of using VHR optical satellite-based monitoring of cetaceans at high temporal frequency and local to global scales, focusing on the UK and UK Overseas Territories as a case study. We assess the primary environmental conditions necessary for the successful application of this technology: cloud cover and wind speed. Five-year monthly median “Total cloud cover” and “10m wind speed” ERA5 global reanalysis data were analyzed to map the spatial feasibility of satellite monitoring. We found that for the United Kingdom, VHR optical satellites could complement existing monitoring methods to achieve greater spatial and temporal coverage of live cetacean surveys, particularly, offshore, during the boreal spring and summer. However, satellites cannot address gaps in UK live cetacean monitoring in winter due to high wind speeds reducing whale detection probability. Based on environmental conditions, the tropics hold the greatest promise for achieving year-round satellite-based cetacean monitoring. In the Falkland Islands, particularly, the remote, unpopulated coastlines of West Island, satellites have the potential to improve strandings monitoring, opportunistically complementing existing stranding monitoring efforts
Sensory pollutants have negative but different effects on nestbox occupancy and breeding performance of a nocturnal raptor across Europe
Full text linkAnthropogenic noise and artificial light at night (ALAN) are expanding globally, acting as pervasive sensory pollutants that can disrupt wildlife behaviour and reproduction. While most research has focused on diurnal species, the effects of these pollutants on the ecological response of nocturnal predators remain poorly understood. Using data from nine European countries, we investigated the effects of traffic noise, ALAN, and road proximity on nestbox occupancy and reproduction in the Tawny Owl (Strix aluco), a nocturnal raptor widespread across Europe. Traffic noise consistently reduced both nestbox occupancy and reproductive success regardless of road proximity. ALAN also impaired occupancy and reproduction, but its negative effect on reproduction changed based on the proximity to roads. Interestingly, the negative effect of ALAN was stronger in sites further from roads, but it attenuated in their proximity, where owls' hatching success and brood size moderately improved. This finding suggests that near roads, where prey abundance and availability are also generally high, owls may either find the prey regardless of ALAN or they may exploit it to facilitate hunting and brood provisioning. However, vicinity to roads might enhance mortality by vehicle collisions, which represents one of the greatest threats for the conservation of owls. Our findings highlight that anthropogenic noise and the co-occurrence between ALAN and roads can affect settlement decisions and breeding performance in nocturnal raptors, with potential consequences across the food chain. Mitigating anthropogenic noise and promoting nighttime-lighting systems that minimize owls' presence close to roads will represent valuable actions to improve their conservation
Restoration of ecological interactions: the influence of site and landscape factors
Full text linkRestoration has been extensively used in agricultural landscapes as a mitigation measure to reduce biodiversity loss in response to historic habitat destruction. Trophic interactions between insects and plants underpin key ecosystem processes and contribute to system robustness, which is a critical outcome for habitat restoration. We evaluate how restoration age, site size and landscape proximity to similar habitats impact the re-establishment of trophic linkages between empirically measured grassland plant-pollinator (60 sites; 1–76 years) and woodland plant-herbivore networks (60 sites; 13–67 years). In each case, sites were selected along a chronosequence with the goal of maximising variation along these temporal and spatial gradients. For both grassland and woodlands, older and larger sites typically support higher levels of connectance, nestedness and generality of the networks. In contrast, landscape proximity promotes these metrics for woodland webs but has the reverse effect for grassland webs. The similarities show common characteristics of community trophic re-establishment in response to local environmental drivers for these different ecosystems. Focusing on interactions rather than species identity highlights opportunities for targeted policies to restore ecosystem function in wider agricultural landscapes; for example, through increasing site size as well as the need for continuity of older sites
Application of measured in vitro dermal bioavailability of polycyclic aromatic hydrocarbons (PAH) in soil in detailed quantitative human health risk assessment
Full text linkOur study shows that site-specific estimates of dermal exposure to selected polycyclic aromatic hydrocarbons contained in contaminated gasworks soil result in lower average daily exposure and risk to human health when compared to the generic assumptions used in risk assessment software. We use site specific in vitro dermal bioavailability flux (μg/cm2/h) for benzo[a]pyrene measured by earlier research published by the authors, where dermal flux provides an analogue of diffusion through the skin and into systemic circulation. We used measured in vitro dermal flux for gasworks contaminated soil containing 150 mg/kg of benzo[a]pyrene to estimate average daily exposure and risk using the Contaminated Land Exposure Assessment (CLEA) framework. Site-specific flux (0.00237 ng/cm2/hour) was used to calculate an uptake of 23.7 ng benzo[a]pyrene/m2 skin/hour, resulting in an average daily exposure (ADE) ranging from 20.7 and 37.3 ng benzo[a]pyrene/kg bw/day for the first six years of a female child’s life. The average ratio of average daily exposure to the Health Criteria Value (Index Dose) was 0.54, where a soil concentration of 278.4 mg/kg is equivalent to a ratio of ADE to Index Dose of one. The results show that for the dermal pathway only the risk to human health calculated using site-specific dermal flux is lower than using default values used in CLEA. In our discussion we highlight that dermal bioavailability varies between sites and PAH and that differences are likely to be influenced by the source of contamination and the physico-chemical properties of soil. The findings support an evidence-based shift toward sample-specific parameters in regulatory risk assessment frameworks, but the scalability, inter-laboratory reproducibility, range and contaminants tested and the cost-effectiveness of in vitro flux testing need to be researched further before broader regulatory adoption
Unlocking river biofilm microbial diversity: a comparative analysis of sequencing technologies
Full text linkFreshwater ecosystems are under increasing pressure from pollution, habitat degradation and climate change, highlighting the need for reliable biomonitoring approaches to assess ecosystem health and identify the causes of biodiversity and ecosystem service loss. Characterisation of freshwater microbiomes has the potential to be an important tool for understanding freshwater ecology, ecosystem health and ecosystem function. High‐throughput sequencing technologies, such as Illumina short‐read and Pacific Biosciences long‐read sequencing, are widely used for microbial community analysis. However, the relative performance of these approaches for monitoring freshwater microbiomes has not been well explored. In this study, we compared the performance of long‐ and short‐read sequencing approaches to assess archaeal and bacterial diversity in 42 river biofilm samples across seven distinct river sites in England by targeting the 16S ribosomal RNA gene. Our findings demonstrated that longer reads generated by PacBio sequencing provide a higher taxonomic resolution, enabling the classification of taxa that remained unassigned in the short‐read Illumina datasets. This enhanced resolution is particularly beneficial for biodiversity assessments because it improves species‐level identification, which is crucial for ecological monitoring. Despite this, both sequencing methods produced comparable bacterial community structures regarding taxon relative abundance, suggesting that the sequencing approach does not profoundly affect the comparative assessment of community composition. However, while Illumina offers higher throughput and cost efficiency, PacBio's ability to resolve complex microbial communities highlights its potential for studies requiring precise taxonomic identification
Ecological drivers of multidimensional temporal beta diversity of phytoplankton communities in a temperate lake over 20 years
No full textUnderstanding how phytoplankton diversity changes over time and the driving mechanisms behind these changes is crucial for the development of freshwater ecosystem conservation policies. However, few studies have simultaneously explored the temporal patterns of lake phytoplankton diversity in three dimensions: taxonomy, function, and phylogeny. Using 20 years (January 1997–December 2016) of plankton monitoring data from Lake Kasumigaura, a temperate lake in Japan, we explored the correlations and ecological drivers between multidimensional temporal beta diversity of lake phytoplankton and their components (i.e., turnover and nestedness). Different dimensions of temporal beta diversity and their components were weakly correlated, suggesting that they provide complementary ecological information. Although temporal beta diversity was found to be primarily driven by stochastic processes, it is worth noting that biotic interactions play a more important role in deterministic processes compared to local environmental and climatic factors. Temporal functional and phylogenetic beta diversity showed a stronger response to deterministic processes compared to temporal taxonomic beta diversity. Our study emphasizes the need for integrated multidimensional biodiversity studies and calls for the incorporation of biological factors in studies of biodiversity drivers
Underground futures: the essential role of the subsurface in a net zero carbon future
No full textThis viewpoint examines the overlooked yet crucial role of the underground in achieving net zero carbon transitions. Drawing on insights from the Underground Futures scoping study, a collaboration between Lancaster University and the British Geological Survey, the viewpoint explores how subsurface spaces, once associated with extraction, are now central to energy storage, carbon sequestration, and geothermal heat generation, and the governance and regulatory challenges this presents. Through interviews and focus groups with UK stakeholders, it identifies governance, limited data, and a lack of integrated planning as major barriers to sustainable underground use. The viewpoint bridges geoscience, spatial planning, and concepts from political geology to ultimately suggest that the underground is a dynamic and active component of planetary change, that is both shaping and being shaped by human efforts toward a sustainable net zero future
Revisiting the age of the Fish Canyon sanidine dating standard
No full textIn 2008, Kuiper and others published an astronomically calibrated age of 28.201 ± 0.046 Ma for the Fish Canyon sanidine (FCs), the most widely used standard in Ar/Ar dating. This age was incorporated in GTS2012 and GTS2020, but has been challenged by later studies that used various approaches, leading again to a ∼ 1.5 % age scattering. This uncertainty hampers the construction of a uniform and coherent time scale that is key to modern high-resolution, multi-disciplinary studies in Earth history. To solve this ongoing uncertainty, we present 1) a visual and statistical re-examination of the astronomical tuning on which the FCs age of 28.201 Ma is based and 2) new single crystal U/Pb ID-TIMS zircon ages of the astronomically calibrated Faneromeni A1 ash bed and the Fish Canyon Tuff (FCT).
Our results corroborate the initial tuning and invalidate astronomical and U/Pb based FCs age calibrations, which are much younger or older. The preferred astronomical calibration seems to converge to a slightly younger age of 28.171–28.176 Ma. This is in good agreement with our new Bayesian zircon eruption age of 28.171 + 0.039/− 0.044 Ma for the FCT and the recently published Bayesian calibration of the 40 K decay scheme with a coupled FCs age of 28.183 ± 0.070 Ma. Importantly, the astronomical and U/Pb-based calibrations now yield similar ages, implying mutual agreement between the three main dating methods to construct our time scale. However, by contrast, the Cretaceous/Paleogene (K/Pg) boundary, which represents a critical triple point for the intercalibration, now produces divergent ages.
In summary, much progress has been made in solving the critical issue of the age of the FCs dating standard. For the moment, we either recommend the continued use of the astronomically calibrated age of 28.201 ± 0.046 Ma or, preferentially, a slightly younger age of 28.171–28.176 Ma. We further endorse investigation in a community-based effort where new data and improved methodologies may lead to further insight into fundamental properties and potentially a definitive age not only for the FCs dating standard, but importantly also for the K/Pg boundary
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