First Multi-Isotopic (Pb-Nd-Sr-Zn-Cu-Fe) Characterisation of Dust Reference Materials (ATD and BCR-723): A Multi-Column Chromatographic Method Optimised to Trace Mineral and Anthropogenic Dust Sources

Atmospheric dust is an integral component of the Earth system with major implications for the climate, biosphere and public health. In this context, identifying and quantifying the provenance and the processes generating the various types of dust found in the atmosphere is paramount. Isotopic signatures of Pb, Nd, Sr, Zn, Cu and Fe are commonly used as sensitive geochemical tracers. However, their combined use is limited by the lack of (a) a dedicated chromatographic protocol to separate the six elements of interest for low-mass samples and (b) specific reference materials for dust. Indeed, our work shows that USGS rock reference materials BHVO-2, AGV-2 and G-2 are not applicable as substitute reference materials for dust. We characterised the isotopic signatures of these six elements in dust reference materials ATD and BCR-723, representatives of natural and urban environments, respectively. To achieve this, we developed a specific procedure for dust, applicable in the 4–25 mg mass range, to separate the six elements using a multi-column ion-exchange chromatographic method and MC-ICP-MS measurements.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Dominant TCR Valpha usage by virus and tumor- reactive T cells with wide affinity ranges for their specific antigens

International audienceWe have studied the TCR features and functional responses of three sets of human cytolytic T cell (CTL) clones, recognizing antigenic peptides presented by HLA-A2 and derived from the Epstein-Barr virus proteins BMLF1 and BRLF1 and from the melanoma protein Melan-A/MART-1. Within each set, a majority of clones used a recurrent V alpha region, even though they expressed highly diverse TCR beta chains and V(D)J junctional sequences. Functional assays and peptide/MHC multimer binding studies indicated that this restricted V alpha usage was not associated with the affinity/avidity of the CTL clones. The V alpha dominance, which may be a frequent feature of antigen-specific T cells, likely reflects a restricted geometry of TCR/peptide/MHC complexes, primarily determined by V alpha CDR

Reading dust provenance in Epica Dome C ice core (East Antarctica): high-resolution, quantitative records from a new Rare Earth Elements (REE) mixing model

Antarctic ice cores are invaluable, direct and high-resolution archives of the past atmosphere and the evolution of Earth’s climate. These unique deposits have revealed tight interplays between dust and climate in Southern Hemisphere. We developed an algorithm (complemented with Monte Carlo simulations) using a large database of REE patterns measured in sediments/soils from well-known dust Potential Source Areas (PSAs) located in the Southern Hemisphere to determine respective contributions of these sources that best fit REE patterns measured in ice cores. We applied this methodology to Epica Dome C (EDC)[1] ice core and provide the first continuous, high-resolution record of dust provenance in Antarctica through the Last Glacial-Interglacial Transition (LGIT-2.9 to 33.7kyr BP). Our reconstructed provenance record is consistent with (i) reported isotopic signature of Antarctic dust and (ii) the climatic evolution of the various PSAs contributing to Antarctic depositions. More importantly, our results compare well with our provenance record in Epica Dronning Maud Land (EDML)[2]. Both cores show a major shift in sources between 14 and 15kyr BP when the contribution of Patagonia (main supplier of dust) fell from ̴55% and ̴70% to 35% and ̴50% in EDC and EDML, respectively. After 14kyr BP, dust from Southern Africa (and to a less extent Australia and New Zealand) became more prevalent from ̴20% and ̴8% to ̴35% and ̴23% in EDC and EDML, respectively. Intriguingly, this compositional shift occurs later than the decline in total dust flux observed between 16-18kyr BP in EDC and EDML. We ascribe this 14-15kyr BP shift in the relative contribution of dust from Patagonia and Southern Africa to (i) long-lasting changes in the hydrology of Patagonian rivers and (ii) a sudden acceleration of sea-level rise at 14.5kyr BP that submerged vast swathes of Patagonian continental shelf, triggering a decline in the supply of Patagonian dust to Antarctica and thus, letting the South African dust contribution to emerge. Overall, our tracing method and dust provenance record in ice core offer a new proxy for the reconstruction of atmospheric paleo-circulation and paleoclimate in the Southern Hemisphere.info:eu-repo/semantics/publishe

High-resolution statistical quantification of aeolian dust provenance in East Antarctica over the Last Glacial-Interglacial Transition

info:eu-repo/semantics/inPres

REE-based reconstruction and quantification of dust flux provenances at EDML, East Antarctica, over the Last Glacial-Interglacial Transition

info:eu-repo/semantics/publishe

First high-resolution reconstruction and quantification of dust flux provenance in East Antarctica over the Last Glacial-Interglacial Transition.

info:eu-repo/semantics/publishe

Identifying the provenance and quantifying the contribution of dust sources in EPICA Dronning Maud Land ice core (Antarctica) over the last deglaciation (7–27 kyr BP): A high-resolution, quantitative record from a new Rare Earth Element mixing model

info:eu-repo/semantics/publishe

Chasing dust in Dronning Maud Land, East Antarctica: A Trace Element perspective

info:eu-repo/semantics/publishe