Geological Survey of Sweden

About: Geological Survey of Sweden is a government organization based out in Uppsala, Sweden. It is known for research contribution in the topics: Metamorphism & Zircon. The organization has 316 authors who have published 671 publications receiving 18333 citations. The organization is also known as: Sveriges Geologiska Undersökning.

Magnetic cues trigger extensive refuelling

Abstract: Long stretches of sea and desert often interrupt the migration routes of small songbirds, whose fat reserves must be restored before these can be crossed as they provide no opportunity for refuelling. To investigate whether magnetic cues might enable inexperienced migratory birds to recognize a region where they need to replenish their body fat, we caught and held thrush nightingales (Luscinia luscinia) in Sweden just before their first migration and exposed them to a magnetic field simulating that at a migratory stopover in northern Egypt, before the Sahara Desert. We found that this magnetic field stimulated the birds to extend their fat-deposition period, indicating that magnetic cues may help small migratory birds to confront large ecological barriers.

Low Atlantic hurricane activity in the 1970s and 1980s compared to the past 270 years

Abstract: The frequency of major hurricanes over the Atlantic Ocean has increased significantly since 1995, but it is still not clear whether this is due to global warming or natural variability. One way to address this question is to consider changes in hurricane frequency in the past, but reliable observations of Atlantic hurricane activity only cover a few decades. Nyberg et al. use proxy records from corals and a marine sediment core that appear to reflect changes in the two main parameters that influence hurricane activity — vertical wind shear and sea surface temperature — to reconstruct the frequency of major hurricanes over the Atlantic since 1730. The results indicate that the frequency was anomalously low during the 1970s and 1980s compared with the past 270 years, and that the phase of increased hurricane frequency since 1995 represents a recovery to 'normal' hurricane activity. These trends appear to be related to wind shear, but what caused this parameter to change remains uncertain. Proxy records from corals and marine sediment core that reflect changes in vertical wind shear and sea surface temperature (the two main parameters that influence hurricane activity) are used to reconstruct the frequency of major hurricanes over the Atlantic since 1730. The results indicate that the frequency of major hurricanes was anomalously low during the 1970s and 1980s compared to the past 270 years. Hurricane activity in the North Atlantic Ocean has increased significantly since 1995 (refs 1, 2). This trend has been attributed to both anthropogenically induced climate change3 and natural variability1, but the primary cause remains uncertain. Changes in the frequency and intensity of hurricanes in the past can provide insights into the factors that influence hurricane activity, but reliable observations of hurricane activity in the North Atlantic only cover the past few decades2. Here we construct a record of the frequency of major Atlantic hurricanes over the past 270 years using proxy records of vertical wind shear and sea surface temperature (the main controls on the formation of major hurricanes in this region1,3,4,5) from corals and a marine sediment core. The record indicates that the average frequency of major hurricanes decreased gradually from the 1760s until the early 1990s, reaching anomalously low values during the 1970s and 1980s. Furthermore, the phase of enhanced hurricane activity since 1995 is not unusual compared to other periods of high hurricane activity in the record and thus appears to represent a recovery to normal hurricane activity, rather than a direct response to increasing sea surface temperature. Comparison of the record with a reconstruction of vertical wind shear indicates that variability in this parameter primarily controlled the frequency of major hurricanes in the Atlantic over the past 270 years, suggesting that changes in the magnitude of vertical wind shear will have a significant influence on future hurricane activity.

Bioaccessibility of metals in urban playground soils.

Abstract: Children ingest soil. The amount ingested varies with the child's behaviour, and daily ingestion rates have been calculated to be between 39 and 270 mg day− 1. During play, children ingest soil both involuntarily and deliberately, and it can be assumed that the latter may result in ingestion of a larger soil particle size fraction and a larger soil mass than the former. Measurements of soil metal contents commonly display the total metal content, where soil sieved to < 2 mm has been digested with strong acids. This procedure does not consider differences in metal contents between size fractions or ingested soil masses. Moreover, it does not consider the difference between bioaccessible and total metal content, possibly resulting in an incorrect evaluation of the potential health risks from soil intake. Intervention and guideline values are commonly calculated via tolerable daily intake values, in turn derived from toxicological studies where the contaminant is administered to a test animal in feed or wate...

40Ar/39Ar mineral dates from retrogressed eclogites within the Baltoscandian miogeocline: Implications for a polyphase Caledonian orogenic evolution

Abstract: Late Proterozoic, rift-facies dolerite dikes within Baltoscandian rocks of the Seve Nappe Complex locally underwent eclogite metamorphism during Caledonian orogenesis. Hornblende from retrograde amphibolite selvages developed around two eclogite boudins exposed at Grapesvare, Norrbotten County, Sweden, record identical 40Ar/39Ar plateau dates of 491 ± 8 Ma. Phengitic muscovite from host schists records plateau dates of 447 ± 7 Ma and 436 ± 7 Ma. Coexisting biotite yields plateau dates of 594 ± 10 Ma and 808 ± 13 Ma. The biotite dates are interpreted to reflect the presence of extraneous argon components. The hornblende and phengitic muscovite ages are interpreted to date times of postmetamorphic cooling through argon retention temperatures. Together with previous 40Ar/39Ar mineral ages from Jamtland, Sweden, they confirm that a significant pre-Scandian tectonothermal event is recorded regionally in allochthonous sequences which originated within the Baltoscandian miogeocline. The eclogite assemblages are interpreted to have formed during westerly subduction of distal portions of the miogeocline with attendant development of an accretionary wedge. The latter was subsequently uplifted and eroded, providing a source for Middle Ordovician through Lower Silurian clastic successions which accumulated in both eastern and western basins. These, together with previously metamorphosed older portions of the miogeocline, were imbricated, folded, and variably metamorphosed during Late Silurian to Early Devonian transport onto the Baltoscandian Platform.