An unprecedented arctic ozone depletion event during spring 2020 and its impacts across Europe

The response of the ozone column across Europe to the extreme 2020 Arctic ozone depletion was examined by analyzing ground-based observations at 38 European stations. The ozone decrease at the northernmost site, Ny-Ålesund (79°N) was about 43% with respect to a climatology of more than 30 years. The magnitude of the decrease declined by about 0.7% deg−1 moving south to reach nearly 15% at 40°N. In addition, it was found that the variations of the ozone column at each of the selected stations in March-May were similar to those observed at Ny-Ålesund but with a delay increasing to about 20 days at mid-latitudes with a gradient of approximately 0.5 days deg−1. The distributions of reconstructed ozone column anomalies over a sector covering a large European area show decreasing ozone that started from the north at the beginning of April 2020 and spread south. Such behavior was shown to be similar to that observed after the Arctic ozone depletion in 2011. Stratospheric dynamical patterns in March–May 2011 and during 2020 suggested that the migration of ozone-poor air masses from polar areas to the south after the vortex breakup caused the observed ozone responses. A brief survey of the ozone mass mixing ratios at three stratospheric levels showed the exceptional strength of the 2020 episode. Despite the stronger and longer-lasting Arctic ozone loss in 2020, the analysis in this work indicates a similar ozone response at latitudes below 50°N to both 2011 and 2020 phenomena

Vícekanálové separační zařízení s paralelní elektrochemickou detekcí

A device with four parallel channels was designed and manufactured by 3D printing in titanium. A simple experimental setup allowed splitting of the mobile phase in four parallel streams, such that a single sample could be analysed four times simultaneously. The four capillary channels were filled with a monolithic stationary phase, prepared using a zwitterionic functional monomer in combination with various dimethacrylate cross-linkers. The resulting stationary phases were applicable in both reversed-phase and hydrophilic-interaction retention mechanisms. The mobile-phase composition was optimized by means of a window diagram so as to obtain the highest possible resolution of dopamine precursors and metabolites on all columns. Miniaturized electrochemical detectors with carbon fibres as working electrodes and silver micro-wires as reference electrodes were integrated in the device at the end of each column. Experimental separations were successfully compared with those predicted by a three-parameter retention model. Finally, dopamine was determined in human urine to further confirm applicability of the developed device.Bylo navrženo a pomocí 3D tisku titanu vyrobeno zařízení se čtyřmi paralelními kanály. Jednoduché experimentální uspořádání umožnilo rozdělit mobilní fázi na čtyři paralelní proudy, tudíž bylo možné analyzovat najednou jeden vzorek čtyřikrát. Čtyři kapilární kanály byly naplněny monolitickou stacionární fází, připravenou ze zwitterionického funkčního monomeru v kombinaci s různých cross-linkery na bázi dimethakrylátu. Výsledné stacionární fáze byly použitelné jak pro retenci v systému obrácených fází, tak i pro HILIC. Složení mobilní fáze bylo optimalizováno okénkovým diagramem pro co největší rozlišení prekurzorů dopaminu a jeho metabolitů na všech kolonách. Miniaturizované elektrochemické detektory z uhlíkových mikroelektrod jako pracovní a stříbrných mikrodrátků jako referentní elektrody byly integrovány do konců každé kolony. Experimentální separace byly úspěšně porovnány s tříparametrickým retenčním modelem. Závěrem byl stanovován dopamin v lidské moči k potvrzení využitelnosti tohoto zařízení

Tectonics, mineralisation and regolith evolution of the West African Craton

Studies of mafic dyke swarms may simultaneously provide information on the mechanical, geochemical, geochronological and magnetic environments at the time of their formation. The mafic intrusive history of different cratons can also be potentially used to unravel their assembly into their current configuration. The identification and classification of dykes is a first step to all these studies. Fortunately, even in regions with poor outcrop, we can use the strong magnetic response of mafic dykes to identify and map their extent. In West Africa the first maps of mafic dyke distribution were made over 40 years ago, but there are still large areas where there are almost no published data. In this paper we present a significantly updated map of mafic dykes for the West Africa Craton based in large part on new interpretations of the regional airborne magnetic database. This map includes the locations of over three thousand dykes across the craton, which locally shows several orientation clusters that provide a minimum estimate for the total number of dyke swarms in this region. Whilst we will have to wait until systematic dating of the different swarms is completed, we can demonstrate that there is a long and complex history of mafic magmatism across the craton, with up to 26 distinct dyke swarms mapped based according to their orientation. The mapping and dating of these swarms will provide key constraints on the assembly of the fragments that make up the modern continents

Multicommodity mineral systems analysis highlighting mineral prospectivity in the Halls Creek Orogen

Understanding the regional context of mineral prospectivity is essential for opening areas to effective exploration. The Halls Creek Orogen in Western Australia, is one such region. Here we have completed a multi-commodity mineral systems analysis, which we have used as a basis for the production of semi-automated prospectivity models. Known mineral occurrences or deposits formed over a period dominated by the compressional 1865-1850. Ma Hooper and 1835-1805. Ma Halls Creek orogenies, either followed, or preceded by periods of extension. Prospectivity models were built on knowledge-based fuzzy inference networks for seven commodity groups. The work has demonstrated a link between key model components and the propensity of disparate styles of mineral deposits to occur in this region, which has not been documented before. Different tectonic terranes defined as 'zones' in the Halls Creek Orogen are prospective for different commodity groups. A link between major crustal-scale faults or shear zones and the location of known ore deposits and occurrences in the area has been established. Many structures are either newly discovered, or their extension through the upper crust and down to the Moho has just been established. The lithospheric scale of these structurally weak zones would allow fluid migration from within, or below the lower crust. Of these structures, orogen perpendicular (northwest trending) and orogen oblique (north trending) faults are the most influential structures with respect to ore deposition, especially in regions where they intersect each other. The orogen-parallel structures were found to be less important. The crustal-scale architecture of the region and its link to known mineral occurrences suggests that the mineral prospectivity of the Halls Creek Orogen for commodities such as Ni, Cu, PGEs, Au, Pb, Zn and diamonds could be extended beyond known occurrences into the new zones delineated by the prospectivity analysis

The (U-Th)/He Chronology and Geochemistry of Ferruginous Nodules and Pisoliths Formed in the Paleochannel Environments at the Garden Well Gold Deposit, Yilgarn Craton of Western Australia: Implications for Landscape Evolution and Geochemical Exploration

Ferruginous nodules and pisoliths that cap deeply weathered profiles and transported cover are characteristic of the Yilgarn Craton, Western Australia. Here we show how ferruginous nodules and pisoliths formed in the paleochannel sediments during Miocene can be used to locate buried Au mineralization. Three types of ferruginous nodules and pisoliths were identified in paleochannel sediments and saprolite, representing different parent materials and environments covering the Garden Well Au deposit: (i) ferruginous nodules formed in saprolite on the flanks of the paleochannel (NSP), (ii) ferruginous pisoliths formed in the Perkolilli Shale in the middle of the paleochannel (PPS) and (iii) ferruginous nodules formed in the Wollubar Sandstone at the bottom of the paleochannel (NWS). The appearance, mineralogy and geochemistry of ferruginous nodules and pisoliths vary according to their origin. The PPS and NWS are goethite-rich whereas NSP is a mixture of goethite and hematite which make them all suitable for (U–Th)/He dating. The average age of goethite in the NSP is 14.8 Ma, in the NWS is 11.2 Ma and in the PPS is 18.6 and 14 Ma. The goethite ages in ferruginous nodules and pisoliths are thought to be younger than the underlying saprolite (Paleocene-Eocene) and were formed in different environmental conditions than the underlying saprolite. Anomalous concentrations of Au, As, Cu, Sb, In, Se, Bi, and S in the cores and cortices of the NWS and the PPS reflect the underlying Au mineralization, and thus these nodules and pisoliths are useful sample media for geochemical exploration in this area. These elements originating in mineralized saprolite have migrated both upwards and laterally into the NWS and the PPS, to form spatially large targets for mineral exploration

DayWater: summary and future development

International audienc