ORCID Profile
0000-0002-0499-3332
Current Organisation
University of Oxford
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Publisher: American Association for the Advancement of Science (AAAS)
Date: 07-06-2019
Abstract: A sediment record reveals a 2-year delayed response following the 2008 Wenchuan earthquake, attributed to monsoon rainfall.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 06-10-2017
Abstract: Mountain glaciation greatly enhances oxidative weathering rates of organic carbon in rocks and associated carbon dioxide release.
Publisher: Elsevier BV
Date: 02-2016
DOI: 10.1016/J.ULTRAS.2015.09.009
Abstract: The acceptance of broadband ultrasound attenuation (BUA) for the assessment of osteoporosis suffers from a limited understanding of both ultrasound wave propagation through cancellous bone and its exact dependence upon the material and structural properties. It has recently been proposed that ultrasound wave propagation in cancellous bone may be described by a concept of parallel sonic rays the transit time of each ray defined by the proportion of bone and marrow propagated. A Transit Time Spectrum (TTS) describes the proportion of sonic rays having a particular transit time, effectively describing the lateral inhomogeneity of transit times over the surface aperture of the receive ultrasound transducer. The aim of this study was to test the hypothesis that the solid volume fraction (SVF) of simplified bone:marrow replica models may be reliably estimated from the corresponding ultrasound transit time spectrum. Transit time spectra were derived via digital deconvolution of the experimentally measured input and output ultrasonic signals, and compared to predicted TTS based on the parallel sonic ray concept, demonstrating agreement in both position and litude of spectral peaks. Solid volume fraction was calculated from the TTS agreement between true (geometric calculation) with predicted (computer simulation) and experimentally-derived values were R(2)=99.9% and R(2)=97.3% respectively. It is therefore envisaged that ultrasound transit time spectroscopy (UTTS) offers the potential to reliably estimate bone mineral density and hence the established T-score parameter for clinical osteoporosis assessment.
Publisher: Springer Science and Business Media LLC
Date: 10-06-2022
DOI: 10.1038/S41467-022-31076-Y
Abstract: Seawater lithium isotopes (δ 7 Li) record changes over Earth history, including a ∼9‰ increase during the Cenozoic interpreted as reflecting either a change in continental silicate weathering rate or weathering feedback strength, associated with tectonic uplift. However, mechanisms controlling the dissolved δ 7 Li remain debated. Here we report time-series δ 7 Li measurements from Tibetan and Pamir rivers, and combine them with published seasonal data, covering small ( 2 km 2 ) to large rivers ( 6 km 2 ). We find seasonal changes in δ 7 Li across all latitudes: dry seasons consistently have higher δ 7 Li than wet seasons, by −0.3‰ to 16.4‰ (mean 5.0 ± 2.5‰). A globally negative correlation between δ 7 Li and annual runoff reflects the hydrological intensity operating in catchments, regulating water residence time and δ 7 Li values. This hydrological control on δ 7 Li is consistent across climate events back to ~445 Ma. We propose that hydrological changes result in shifts in river δ 7 Li and urge reconsideration of its use to examine past weathering intensity and flux, opening a new window to reconstruct hydrological conditions.
Publisher: American Geophysical Union (AGU)
Date: 06-2022
DOI: 10.1029/2022JG006824
Abstract: The delivery and burial of terrestrial particulate organic carbon (OC) in marine sediments is important to quantify, because this OC is a food resource for benthic communities, and if buried it may lower the concentrations of atmospheric CO 2 over geologic timescales. Analysis of sediment cores has previously shown that fjords are hotspots for OC burial. Fjords can contain complex networks of submarine channels formed by seafloor sediment flows, called turbidity currents. However, the burial efficiency and distribution of OC by turbidity currents in river‐fed fjords had not been investigated previously. Here, we determine OC distribution and burial efficiency across a turbidity current system within Bute Inlet, a fjord in western Canada. We show that 62% ± 10% of the OC supplied by the two river sources is buried across the fjord surficial (30–200 cm) sediment. The sandy subenvironments (channel and lobe) contain 63% ± 14% of the annual terrestrial OC burial in the fjord. In contrast, the muddy subenvironments (overbank and distal basin) contain the remaining 37% ± 14%. OC in the channel, lobe, and overbank exclusively comprises terrestrial OC sourced from rivers. When normalized by the fjord’s surface area, at least 3 times more terrestrial OC is buried in Bute Inlet, compared to the muddy parts of other fjords previously studied. Although the long‐term ( years) preservation of this OC is still to be fully understood, turbidity currents in fjords appear to be efficient at storing OC supplied by rivers in their near‐surface deposits.
Publisher: Wiley
Date: 13-02-2022
Publisher: Wiley
Date: 11-02-2022
Publisher: American Association for the Advancement of Science (AAAS)
Date: 05-06-2020
Abstract: Large earthquakes shape mountain landscapes at high elevations.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Robert Hilton.