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Only few datasets on scandium (Sc) and rare earths and yttrium (REY) in rivers are available and the behaviour of Sc in the hydrosphere is poorly understood. We determined Sc and REY concentrations in the dissolved fraction of twelve boreal rivers in Sweden, which show low conductivity, circumneutral pH and elevated dissolved organic carbon (DOC). Scandium concentrations vary between 189 and 1170 pmol/l and are at the high end of the range reported for rivers worldwide. Unusually high Sc concentrations in the Dalsälven and Västerdalälven could be tracked to the Vanån, a tributary to the headwaters of the latter. Increasing Sc with increasing DOC and Yb concentrations suggest that organic ligands play a major role in the distribution of Sc. The REYSN patterns are similar for all rivers (except the Västerdalälven) and are slightly light REY-depleted with negative Ce and Eu anomalies, and positive Y anomalies. These patterns appear to be a general feature of freshwater draining the Fennoscandian Shield into the Baltic Sea for at least the past 28 years. Our results clearly demonstrate that Sc and REY are fractionated in river waters relative to their crustal source and that they should not be discussed jointly as "REE". [ABSTRACT FROM AUTHOR]

Scandium is a critical raw material that is essential for the EU economy because of its potential application in enabling technologies such as fuel cells and lightweight materials. As there is currently no secure supply of Sc, several projects worldwide evaluate potential Sc sources. While elsewhere in Europe emphasis is placed upon secondary resources such as red mud, we investigated the potential of industrial garnet sand and its waste products. Since Sc readily substitutes for Mg and Fe in the crystal lattice of garnet, the garnet minerals almandine and pyrope, in particular, may show high Sc concentrations. Garnet sand, after being used as an abrasive in the cutting and sandblasting industry, is recycled several times before it is finally considered waste which eventually must be disposed of. Extraction of Sc (and rare earth elements, REE) from such garnet sand may generate added value and thereby reduce disposal cost. The studied garnet sands from different mines in Australia, India and the U.S., and industrial garnet sands commercially available in Germany from different suppliers show average Sc concentrations of 93.7 mg/kg and 90.7 mg/kg, respectively, i.e. similar to red mud. Our data also show that "fresh" and recycled garnet sands yield similar Sc concentrations. Within the framework of a minimum-waste approach, it may be feasible to utilize the industrial waste-product "garnet sand" as an unconventional source of Sc and REE, that reduces disposal cost. [ABSTRACT FROM AUTHOR]

It is widely assumed that atmospheric oxygen concentrations remained persistently low (less than 10−5 times present levels) for about the first 2 billion years of Earth's history. The first long-term oxygenation of the atmosphere is thought to have taken place around 2.3 billion years ago, during the Great Oxidation Event. Geochemical indications of transient atmospheric oxygenation, however, date back to 2.6-2.7 billion years ago. Here we examine the distribution of chromium isotopes and redox-sensitive metals in the approximately 3-billion-year-old Nsuze palaeosol and in the near-contemporaneous Ijzermyn iron formation from the Pongola Supergroup, South Africa. We find extensive mobilization of redox-sensitive elements through oxidative weathering. Furthermore, using our data we compute a best minimum estimate for atmospheric oxygen concentrations at that time of 3 × 10−4 times present levels. Overall, our findings suggest that there were appreciable levels of atmospheric oxygen about 3 billion years ago, more than 600 million years before the Great Oxidation Event and some 300-400 million years earlier than previous indications for Earth surface oxygenation. [ABSTRACT FROM AUTHOR]

Opinion. Presents information on the lanthanide effect in highly evolved felsic igneous rocks which is a response to the comment made by Y. Pan. Use of the term `lanthanide tetrad effect'; Perception of the individual as it pertains to subject.