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Towards sustainable lake restoration
No full textSustainable lake restoration has been introduced recently as a strategy to address ecological, economic, and social challenges in nutrient management. The strategy would benefit at least 40 % of the world's lakes through addressing eutrophication, and the impact becomes even broader if we consider the complex nature of eutrophication (its linkage to multiple environmental problems). This approach involves: 1) demonstrating broader social and economic benefits, 2) integrating circular economies, and 3) directly engaging local communities in co-developing restoration goals, targets and monitoring. The current study explores opportunities to advance sustainable lake restoration using a well-established model that fosters interaction among restoration stakeholders. We assessed each model step for sustainability needs, identifying knowledge gaps and key factors for future success. We emphasize the need for a better understanding of the linkages between eutrophication and other environmental problems, proper monitoring programs to demonstrate broader restoration benefits, effective system analysis tools, sustainable nutrient recycling measures and accurate realization, and thorough documentation for life-cycle assessments. Achieving these goals requires significant policy and financing transformations, continuous engagement, and close collaboration among all stakeholders
The geothermal potential of early Carboniferous limestone in the UK
Get PDF• The thermal springs in Bath, Bristol, the Taff Valley and the Peak District are formed where early
Carboniferous limestone rocks come to surface
• Where the limestone is buried in the subsurface, groundwater flowing through it creates
potential for geothermal energy in the UK
• The groundwater could be exploited via geothermal doublets, for direct-use heat, or heat
pumps for heating, cooling and thermal storage; geothermal energy can also be used in
conjunction with district heating networks
• Areas of potential summarised here from legacy reports are:
» East Midlands, northern West Midlands and northern England (northern province)
» Mendip Hills and South Wales (southern province)
» Northern Ireland
• Many of these areas are close to urban settlements and therefore heat demand
• Geothermal potential is controlled by the ability of groundwater to flow through the rock and
is significantly affected by processes that create porosity and permeability some time after the
rock was deposited (secondary porosity
World mineral production 2019-23
Get PDFWelcome to the latest edition of World Mineral Production which includes global mineral production data for 2023. This is a continuation of the dataset that began in 1913.
This publication is compiled from a comprehensive database, maintained by the British Geological Survey (BGS), through which we aim to provide a reliable and continuous set of data covering most of the minerals that enter international trade. In this volume we set out the production figures by country for more than 70 mineral commodities over the five-year period from 2019 to 2023. The objective of this series remains to present the latest production information obtained from official bodies in individual countries, although other sources are also used to ensure completeness and accuracy. The cooperation afforded to the BGS by numerou
How Alluvial Storage Controls Spatiotemporal Water Balance Partitioning in Intermittent and Ephemeral Stream Systems
Get PDFThe hydrological dynamics of intermittent rivers and ephemeral streams (IRES) impacts the availability of water to riparian ecosystems, the height of downstream runoff peaks, and the replenishment of groundwater systems. Despite its significance, the influence of superficial geology on IRES flow processes remains an area of limited understanding. Here we first present a comprehensive data set encompassing streamflow and groundwater levels from an intermittent stream situated in New South Wales, Australia. We then use targeted geophysical investigations to show how the configurations of superficial geology control the streamflow and groundwater responses. The analysis reveals that periods of stable stream stage consistently occur after episodic surges in streamflow, followed by recession and channel desiccation. The duration of the stable phases exhibits an upstream-to-downstream pattern, reaching a maximum of 44 ± 3 days upstream and then abruptly declining further downstream. There is remarkable consistency in the duration of these stable flow periods, irrespective of the size of preceding streamflow peaks. We propose two primary controls of this behavior: (a) variability in permeability contrasts between channel alluvium and surrounding geological deposits, and (b) longitudinal fluctuations in the volume of the recent channel alluvial reservoir. The interplay of these controls generates a “goldilocks zone,” which optimizes riparian water availability and the potential for groundwater recharge in IRES landscapes. These geological controls may reflect a continuum present in other dryland catchments with widespread implications for groundwater recharge and stream classification based on flow occurrence and duration
Shelf-edge glaciation offshore of northeast Greenland during the last glacial maximum and timing of initial ice-sheet retreat
Get PDFThis paper presents new marine geophysical data and radiocarbon dated sediment cores to reconstruct the maximum extent of the Northeast Greenland Ice Stream (NEGIS) during the last glaciation and the timing of its initial retreat from the continental shelf. The NEGIS is the largest ice stream to drain the Greenland Ice Sheet (GrIS) today, and holds a sea-level equivalent of 1.1–1.4 m. It has undergone recent retreat but the longer-term history of NEGIS on the adjoining continental shelf is still relatively poorly constrained. Two cross-shelf bathymetric troughs, Westwind and Norske troughs, acted as pathways for offshore-flowing ice during the last glaciation but little is known about the acoustic stratigraphy, sedimentology and chronology of ice sheet retreat in the outer shelf sections of both troughs. Multibeam swath bathymetry and acoustic data from both troughs show flow parallel and flow transverse glacial landforms in the outer shelf sections of both troughs. Mega-scale glacial lineations in Westwind Trough record former streaming flow towards the shelf-edge. Grounding-zone wedges record episodic stabilisation during retreat from the shelf-edge. Sediment cores recovered subglacial tills and grounding-zone proximal sediments overlain by glacimarine sediments. The slope beyond Norske Trough is characterised by glacigenic debris flows typical of submarine slopes offshore of shelf-edge terminating palaeo-ice streams. Radiocarbon dates indicate that initial retreat of the ancestral NEGIS from the northeast Greenland shelf-edge was underway by 21.5–21.6 cal ka BP in Norske Trough and c. ≥19.0 cal ka BP in Westwind Trough. Retreat rates across the outer shelf were slow at 19–23 m a−1 but increased across the inner shelf. Our data provides the first direct chronological support for a shelf-edge terminating GrIS offshore of northeast Greenland during the last glacial maximum and demonstrates this sector of the GrIS underwent relatively early retreat from the shelf-edge
Conservation changed but not divided [Letter]
No full textWe acknowledge the valuable perspectives presented in the letter by Murray et al. in response to our recent publication. They highlight the risk that artificial intelligence (AI) may divide conservation if ecological and field experience do not underpin the design of AI tools, and if AI capacity in the Global South does not develop to avoid further scientific inequities. We agree wholeheartedly with these points and recognise that the task of equitable integration of AI into conservation is beyond the scope of any single group and requires collective action. We take this opportunity to further develop our original discussion, and to elaborate how we think equitable integration of AI into conservation may be achieved and the potential roles of different actors, to enable conservation to be changed, but not divided
Land‐to‐sea sediment fluxes From a major glacial lake outburst flood were stepped rather than instantaneous
Get PDFGlacial lake outburst floods can transport large volumes of sediment. Where these floods reach the coastline, much of the particulate matter is delivered directly to the marine environment. It has been suggested that offshore deposits, specifically in fjord settings, may provide a faithful record of past outburst flood events. However, a lack of observations means that the mechanics and the timing of sediment transport offshore following a glacial lake outburst event remain poorly constrained. Here, we document the changes in sea surface sediment dynamics following the 28 November 2020 Elliot Lake outburst flood in British Columbia, which transported ∼4.3 × 106 m3 of sediment into an adjacent fjord (Bute Inlet) as a deep nepheloid layer directly following the event. However, analysis of sea surface turbidity using in situ measurements and satellite-derived estimates reveals that changes in fjord-head surface turbidity in the months following the major flood were surprisingly small. The highest measured sea surface turbidity instead occurred 5 months after the initial outburst flood. This delayed increase in seaward sediment flux coincided with the onset of the spring freshet, when the discharge of the rivers feeding Bute Inlet increases each year. We suggest that large quantities of sediment were temporarily stored within the river catchment and were only remobilized when river discharge exceeded a threshold level following seasonal snowmelt. Our results reveal a temporal disconnect, where onshore to offshore transfer of sediment is stepped following a glacial lake outburst flood, which could complicate the sedimentology of subsequent deposits
Historical geomagnetic observations from the Netherlands during the Carrington event (1859)
Get PDFThe Carrington event of September 1859 is the best known example of an extreme geomagnetic storm, often cited when discussing space weather risks for modern infrastructure. Historic observations including auroral sightings, magnetometer records and anecdotes of impacts on telegraph systems have been widely shared before, but none of these have included observations from the Netherlands. Geomagnetic observations taken in Utrecht and Den Helder during the Carrington event were digitised from the Royal Netherlands Meteorological Institute’s (KNMI) yearbook of 1859, and compared to much more detailed magnetograms from London. This combined analysis, beyond its application in communication with Dutch stakeholders, contributes to a better understanding of the interpretation, limitations, and uses of such archived measurements, of which more examples might be available in archives internationally. The observations consist of spot measurements taken three times per day. The Den Helder data only partially record the Carrington storm. Conversion factors from Den Helder have been used to estimate missing conversion factors of the Utrecht data. The correlation between the Dutch declination measurements and those made in London is strong with correlation coefficients larger than 0.7 for the Utrecht data and larger than 0.9 for the Den Helder data. However, there is very little correlation between the Dutch and British inclination measurements. The London horizontal intensity measurements compared to Den Helder data give correlation values larger than 0.8 but the observations from Utrecht match less well. There is a significant deviation between the British data and the Utrecht declination and horizontal intensity measurements during the quiet period between 30 August and 2 September. It is unclear what causes this deviation. Given the proximity of the locations and similarity in latitude, and based on the coherent registration of the measurements, it is reasonable to assume that the magnetic traces captured in London provide a good approximation of the magnetic field variations in the Netherlands during the storm, indicating that these may be used for impact assessment studies for Dutch vital infrastructure
Subglacial Conditions From Converted-Wave Seismic Reflection Amplitudes: Synthetic Experiments and Case Study Reveal a Frozen Bed at an Antarctic Ice Rise
Get PDFUnderstanding how an ice sheet slips at its base is an important part of ice sheet models; this requires knowledge of the geological materials underlying the ice. Controlled-source seismic surveys which estimate the amplitude of the seismic waves reflected from the ice base are a common means of inferring the properties of these materials. Typically, these surveys are sensitive to reflected compressional (PP) waves only; this excludes important information contained in the waves converted to shear waves (PS) when reflected at the ice base. This study investigates how inferences of glacier bed properties may be improved by joint analysis of PP and PS waves. Using synthetic data, we demonstrate that joint analysis improves upon the conventional method in both precision and accuracy. Analysis of PS waves may allow accurate ice base properties to be retrieved using smaller survey geometries than those intended for PP analysis only. Our method provides the greatest improvement when soft sediment or water is beneath the ice. We apply the method to data from Korff Ice Rise, West Antarctica, inferring that the ice base is frozen
Diversity hosted by moss carpets in the Amazonian forest of Amapá, new insights from DNA metabarcoding
Get PDFBryophytes play an important role as habitats for many organisms, especially invertebrates, however, few studies have focused on understanding the cryptic ecosystems associated with them. The use of molecular tools allows for advances in diversity assessment of environmental samples. In particular, the use of DNA metabarcoding is an efficient method for detection of the DNA of rare and cryptic species, including resting stages typically undetected in morphological surveys. We used DNA metabarcoding to investigate the hidden diversity present in two moss carpets in the largest of the world’s remaining rainforests, the Amazon. More specifically, our samples took place in the Brazilian state of Amapá, the least affected by anthropogenic pressures. Samples, 10 m apart, were collected under sterile conditions and eDNA was extracted. To maximize diversity coverage, three regions were sequenced (ITS2, COX1 and 16S). A total of 348 taxa were assigned from the sequences obtained, with 123 eukaryotic taxa representing five Kingdoms assigned from COX1, 64 representing four Kingdoms from ITS2 and 161 representing one prokaryotic Domain from the 16S region. A total of 38% of taxa were Fungi, 35% Bacteria and 27% non-fungal eukaryotes. The data obtained highlight the importance of moss carpets providing habitats that support diverse communities. Given the high number of unassigned sequences, the available sequence databases for Amazonian species require improvement. As the region faces multiple threats, there is an urgent need for improvements in collection, identification ability, sequencing and DNA curation. There were several assignments of disease-causing organisms, this highlights the need for monitoring changes in these under-researched habitats
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