CO2 content beneath northern Iceland and the variability of mantle carbon

Primitive basalt melt inclusions from Borgarhraun, northern Iceland, display large correlated variations in CO2 and non-volatile incompatible trace elements (ITEs) such as Nb, Th, Rb, and Ba. The average CO2/ITE ratios of the Borgarhraun melt inclusion population are precisely determined (e.g., CO2/Nb = 391 ± 16; 2M, n = 161). These data, along with published data on five other populations of undegassed MORB glasses and melt inclusions, demonstrate that upper mantle CO2/Ba and CO2/Rb are nearly homogenous, while CO2/Nb and CO2/Th are broadly correlated with long-term indices of mantle heterogeneity reflected in Nd isotopes (143Nd/144Nd) in five out of the six regions of the upper mantle examined thus far. Our results suggest that heterogeneous carbon contents of the upper mantle are long-lived features, and that average carbon abundances of the mantle sources of Atlantic mid-ocean ridge basalts (MORB) are higher by a factor of two than those of Pacific MORB. This observation is correlated with a similar distinction in water contents (Michael, 1995) and trace elements characteristic of subduction fluids (Ba, Rb; Arevalo and McDonough, 2010). We suggest that the upper mantle beneath the younger Atlantic Ocean basin contains components of hydrated and carbonated subduction-modified mantle from prior episodes of Iapetus subduction that were entrained and mixed into the upper mantle during opening of the Atlantic Ocean basin.Maclennan is supported by Natural Environment Research Council grant NE/M000427/1. This research was supported by the Carnegie Institution of Washington and is a contribution to the Deep Carbon Observatory

Sulfur, Chlorine, and Flourine Degassing and Atmospheric Loading by the 1783 - 1784 AD Laki (Skaftar Fires) Eruption in Iceland

The 1783-1784 Laki tholeiitic basalt fissure eruption in Iceland was one of the greatest atmospheric pollution events of the past 250 years, with widespread effects in the northern hemisphere. The degassing history and volatile budget of this event are determined by measurements of pre-eruption and residual contents of sulfur, chlorine, and fluorine in the products of all phases of the eruption. In fissure eruptions such as Laki, degassing occurs in two stages: by explosive activity or lava fountaining at the vents, and from the lava as it flows away from the vents. Using the measured sulfur concentrations in glass inclusions in phenocrysts and in groundmass glasses of quenched eruption products, we calculate that the total accumulative atmospheric mass loading of sulfur dioxide was 122 Mt over a period of 8 months. This volatile release is sufficient to have generated approximately 250 Mt of H2SO4 aerosols, an amount which agrees with an independent estimate of the Laki aerosol yield based on atmospheric turbidity measurements. Most of this volatile mass (approximately 60 wt.%) was released during the first 1.5 months of activity. The measured chlorine and fluorine concentrations in the samples indicate that the atmospheric loading of hydrochloric acid and hydrofluoric acid was approximately 7.0 and 15.0 Mt, respectively. Furthermore, approximately 75% of the volatile mass dissolved by the Laki magma was released at the vents and carried by eruption columns to altitudes between 6 and 13 km. The high degree of degassing at the vents is attributed to development of a separated two-phase flow in the upper magma conduit, and implies that high-discharge basaltic eruptions such as Laki are able to loft huge quantities of gas to altitudes where the resulting aerosols can reside for months, or even 1-2 years. The atmospheric volatile contribution due to subsequent degassing of the Laki lava flow is only 18 wt.% of the total dissolved in the magma, and these emissions were confined to the lowest regions of the troposhere and therefore important only over Iceland. This study indicates that determination of the amount of sulfur degassed from the Laki magma batch by measurements of sulfur in the volcanic products (the petrologic method) yields a result which is sufficient to account for the mass of aerosols estimated by other methods

CO2 content beneath northern Iceland and the variability of mantle carbon

Primitive basalt melt inclusions from Borgarhraun, northern Iceland, display large correlated variations in CO2 and nonvolatile incompatible trace elements (ITEs) such as Nb, Th, Rb, and Ba. The average CO2/ITE ratios of the Borgarhraun melt inclusion population are precisely determined (e.g., CO2/Nb = 391 ± 16; 2σM [two standard errors of the mean], n = 161). These data, along with published data on five other populations of undegassed mid-oceanic ridge basalt (MORB) glasses and melt inclusions, demonstrate that upper mantle CO2/Ba and CO2/Rb are nearly homogeneous, while CO2/Nb and CO2/Th are broadly correlated with long-term indices of mantle heterogeneity reflected in Nd isotopes (143Nd/144Nd) in five of the six regions of the upper mantle examined thus far. Our results suggest that heterogeneous carbon contents of the upper mantle are long-lived features, and that average carbon abundances of the mantle sources of Atlantic MORB are higher by a factor of two than those of Pacific MORB. This observation is correlated with a similar distinction in water contents and trace elements characteristic of subduction fluids (Ba, Rb). We suggest that the upper mantle beneath the younger Atlantic Ocean basin contains components of hydrated and carbonated subduction-modified mantle from prior episodes of Iapetus subduction that were entrained and mixed into the upper mantle during opening of the Atlantic Ocean basin

Narrow genetic basis for the Australian dingo confirmed through analysis of paternal ancestry

The dingo (Canis lupus dingo) is an iconic animal in the native culture of Australia, but archaeological and molecular records indicate a relatively recent history on the continent. Studies of mitochondrial DNA (mtDNA) imply that the current dingo population was founded by a small population of already tamed dogs from Southeast Asia. However, the maternal genetic data might give a unilateral picture, and the gene pool has yet to be screened for paternal ancestry. We sequenced 14,437 bp of the Y-chromosome (Y-chr) from two dingoes and one New Guinea Singing Dog (NGSD). This positioned dingo and NGSD within the domestic dog Y-chr phylogeny, and produced one haplotype not detected before. With this data, we characterized 47 male dingoes in 30 Y-chr single-nucleotide polymorphism sites using protease-mediated allele-specific extension technology. Only two haplotypes, H3 and H60, were found among the dingoes, at frequencies of 68.1 and 31.9 %, respectively, compared to 27 haplotypes previously established in the domestic dog. While H3 is common among Southeast Asian dogs, H60 was specifically found in dingoes and the NGSD, but was related to Southeast Asian dog Y-chr haplotypes. H3 and H60 were observed exclusively in the western and eastern parts of Australia, respectively, but had a common range in Southeast. Thus, the Y-chr diversity was very low, similar to previous observations for d-loop mtDNA. Overall genetic evidence suggests a very restricted introduction of the first dingoes into Australia, possibly from New Guinea. This study further confirms the dingo as an isolated feral dog. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10709-012-9658-5) contains supplementary material, which is available to authorized users

Protect the natives to combat the aliens: Could octopus vulgaris cuvier, 1797 be a natural agent for the control of the lionfish invasion in the mediterranean sea?

[No abstract available

The association of circulating amylin with β-amyloid in familial Alzheimer's disease.

INTRODUCTION: This study assessed the hypothesis that circulating human amylin (amyloid-forming) cross-seeds with amyloid beta (Aβ) in early Alzheimer's disease (AD). METHODS: Evidence of amylin-AD pathology interaction was tested in brains of 31 familial AD mutation carriers and 20 cognitively unaffected individuals, in cerebrospinal fluid (CSF) (98 diseased and 117 control samples) and in genetic databases. For functional testing, we genetically manipulated amylin secretion in APP/PS1 and non-APP/PS1 rats. RESULTS: Amylin-Aβ cross-seeding was identified in AD brains. High CSF amylin levels were associated with decreased CSF Aβ42 concentrations. AD risk and amylin gene are not correlated. Suppressed amylin secretion protected APP/PS1 rats against AD-associated effects. In contrast, hypersecretion or intravenous injection of human amylin in APP/PS1 rats exacerbated AD-like pathology through disruption of CSF-brain Aβ exchange and amylin-Aβ cross-seeding. DISCUSSION: These findings strengthened the hypothesis of circulating amylin-AD interaction and suggest that modulation of blood amylin levels may alter Aβ-related pathology/symptoms

Compositional characteristics and spatial distribution of enriched Icelandic mantle components

Author Posting. © The Authors, 2010. This is the author's version of the work. It is posted here by permission of Oxford University Press for personal use, not for redistribution. The definitive version was published in Journal of Petrology 51 (2010): 1447-1475, doi:10.1093/petrology/egq025.We present compositional data on a suite of 18 primitive neovolcanic alkali basalts from three flank zone regions in Iceland (Vestmannaeyjar in the south, Snæfell in the east, and Snæfellsnes in the west) that are peripheral to the main rift zones that are dominated by tholeiitic basalts. This study integrates He isotope data with radiogenic isotope data (Sr-Nd-Pb-Hf), stable isotope data (δ18O), and trace element data to characterise the compositional features of the trace-elementenriched components of the Icelandic mantle. We also present high-precision Pb isotope data on an additional 57 lava samples from the flank zones (including Öræfajökull in the south-east) and the Northern and Eastern rift zones. Most Icelandic lavas have negative Δ207Pb (–4 to –1), with higher values (–1 to +4) found only in samples from Öræfajökull, Snæfell, and parts of the Reykjanes Peninsula. At Snæfell, this EM1-type component is characterised by a low δ18Oolivine signature (+4.1‰ to +4.6‰), moderate 206Pb/204Pb values (18.4-18.6) and MORB-like 3He/4He (6.9-7.5 R/RA). Samples from Vestmannaeyjar and Snæfellsnes have mantle-like δ18Oolivine (+4.9‰ to +5.0‰), and radiogenic 206Pb/204Pb values (18.9-19.3) that fall on the NHRL for 208Pb/204Pb (Δ208Pb –5 to +5). Compared to the Vestmannaeyjar lavas, Snæfellsnes lavas have higher La/YbN (5-11 vs. 3-5), lower εNd (5.5-6.5 vs. 6.8-7.6) and lower 3He/4He (6.3-8.6 R/RA vs. 11.4-13.5 R/RA). Therefore, the most trace element enriched components in the Icelandic mantle are not the carriers of the high 3He/4He values (> 15 R/RA) found in some lavas on Iceland and the adjacent ridges, and instead are consistent with degassed, recycled components. Even after excluding the EM1-type high Δ207Pb samples, high-precision Pb isotope data produce a kinked array on an 206Pb/204Pb vs. 208Pb/204Pb plot, which is not consistent with simple binary mixing between two end-members. This requires significant lateral heterogeneity within the Icelandic mantle and the presence of more than just two compositionally-distinct local mixing end-member components. Samples from each of the main axial rift zones define different trends. Despite the tectonic continuity between the Northern Volcanic Zone and the Eastern Volcanic Zone, lavas from these two rift zones define separate sub-parallel linear arrays. Lavas from the adjacent Western Volcanic Zone and the Eastern Volcanic Zone define oblique linear arrays that converge on a common local end-member that is not involved in the magmatism of the Northern Volcanic Zone. Therefore, there is a distinct NE-SW compositional heterogeneity within the Icelandic mantle.work was funded primarily by the Danish National Research Foundation through a grant to the former Danish Lithosphere Centre, with additional funding from the University of Iowa for the oxygen isotope analyses

The ALICE TPC, a large 3-dimensional tracking device with fast readout for ultra-high multiplicity events

The design, construction, and commissioning of the ALICE Time-Projection Chamber (TPC) is described. It is the main device for pattern recognition, tracking, and identification of charged particles in the ALICE experiment at the CERN LHC. The TPC is cylindrical in shape with a volume close to 90 m^3 and is operated in a 0.5 T solenoidal magnetic field parallel to its axis. In this paper we describe in detail the design considerations for this detector for operation in the extreme multiplicity environment of central Pb--Pb collisions at LHC energy. The implementation of the resulting requirements into hardware (field cage, read-out chambers, electronics), infrastructure (gas and cooling system, laser-calibration system), and software led to many technical innovations which are described along with a presentation of all the major components of the detector, as currently realized. We also report on the performance achieved after completion of the first round of stand-alone calibration runs and demonstrate results close to those specified in the TPC Technical Design Report.Comment: 55 pages, 82 figure

Protect the Natives to Combat the Aliens: Could Octopus vulgaris Cuvier, 1797 Be a Natural Agent for the Control of the Lionfish Invasion in the Mediterranean Sea?

Biological invasions constitute a major threat to native ecosystems and to global biodiversity [...]</jats:p