Late Pleistocene–Holocene environmental and climatic history of a freshwater paramo ecosystem in the northern Andes

This study presents the first multi-proxy palaeoenvironmental and palaeoclimatic history for northern South America based on the palaeolimnological reconstruction of a pond located in a dry paramo at 3570 masl. During the Last Glacial Maximum (LGM), the study area was under glacial conditions, then during global events Heinrich Stadial 1 (HS1), Bølling–Allerød (BA), and the Younger Dryas (YD), the pond expanded, accumulation rates and proxies for erosion reached the highest values, indicative of humid conditions, with maxima in humidity during the BA and YD. Dry conditions and pond desiccation occurred in the Greenlandian–Northgrippian and by 6010 cal a bp the area was transformed into the mire of today. Comparisons with records from other sites in South America indicate that changes in humidity are most likely controlled by the Intertropical Convergence Zone, mainly during the glacial and postglacial, and by changes in the Pacific Ocean, more pronounced after the YD.     

People’s capacities in facing hazards and disasters: an overview

Natural Hazards - This article constitutes an effort towards providing an academic overview and grounding for the concept of capacities in the context of disaster studies and disaster risk...     

Fahien reconsidered: Pleistocene exploitation of wild bananas and Holocene introduction of Musa cultivars to Sri Lanka

A recent publication on the phytolith assemblage at Fahien rockshelter, Sri Lanka (Premathilake and Hunt) is argued to represent: the exploitation of wild Musa acuminata and M. balbisiana during the Late Pleistocene; the introduction of edible diploid cultivars from the Southeast Asia–New Guinea region during the early to mid‐Holocene; the generation and cultivation of triploid banana hybrids on Sri Lanka before 6194–5994 cal bp ; and the subsequent spread of derived triploid cultivars to mainland India and westward to Africa. A careful review of the archaeobotanical research presented by Premathilake and Hunt, in the context of broader multidisciplinary evidence (agronomy, archaeobotany, genetics and linguistics) for the domestication and spread of banana cultivars, indicates that three main aspects of their argument are problematic: the lack of clarity in the characterization of banana domestication in the past; the methods used to discriminate phytoliths into banana taxa; and the promotion of Sri Lanka as a source region rather than a recipient of banana cultivars. Following reconsideration, the Fahien evidence is consistent with previous interpretations for the origins of diploid and significant triploid cultivars outside of Sri Lanka and dispersal to that island. © 2019 John Wiley & Sons, Ltd.     

Petrology of pumices of April 1993 eruption of Lascar (Atacama, Chile)

Lascar Volcano (Atacama, Chile) erupted on 18–20 April 1993. Several sub-Plinian explosions occurred, and some were mushroom-shaped. The highest column rose up to 23 km. Ash clouds crossed South America eastwards. Dacite pumice falls made of blocks and ashes were deposited on the flanks of the volcano as a result of collapsed columns. The pumice contains phenocrysts of plagioclase, enstatite, augite, biotite, magnetite and ilmenite and small crystals of apatite. The 1992 previous andesite dome inside the crater was destroyed. Banded blocks resulting from mingling of the dacitic pumice and andesite from the dome are found in the pumice flow. Both the lava dome and the pumice are representative of the Lascar high-K magma unit. Dacitic pumice is a product of crystal fractionation of the andesitic magma.     

High-Frequency Response of the Atmospheric Electric Potential Gradient Under Strong and Dry Boundary-Layer Convection

The spectral response of atmospheric electric potential gradient gives important information about phenomena affecting this gradient at characteristic time scales ranging from years (e.g., solar modulation) to fractions of a second (e.g., turbulence). While long-term time scales have been exhaustively explored, short-term scales have received less attention. At such frequencies, space-charge transport inside the planetary boundary layer becomes a sizeable contribution to the potential gradient variability. For the first time, co-located (Évora, Portugal) measurements of boundary-layer backscatter profiles and the 100-Hz potential gradient are reported. Five campaign days are analyzed, providing evidence for a relation between high-frequency response of the potential gradient and strong dry convection.     

Rainfall intensity patterns derived from the urban network of Barcelona (NE Spain)

Theoretical and Applied Climatology - An analysis of the normalised rainfall intensity curves in Barcelona (NE Spain) has been undertaken from 41 selected rain rate episodes recorded by an urban...     

Clashing interpretations of REDD+ “results” in the Amazon Fund

Results-based funding (RBF) is a governance concept that is rapidly becoming the mainstream paradigm for international collaborations in the environmental sector. While portrayed as a compromise solution between market-based mechanisms and unconditional donations, the implementation of RBF is revealing new conflicts and contradictions of its own. This paper explores the application of RBF for Reducing Emissions from Deforestation and Forest Degradation (REDD+) by describing the discursive conflicts between recipient (i.e., Brazil) and donor (i.e., Norway and Germany) countries of the Amazon Fund about what constitutes “results” or “performance.” Although all parties agree that the financial transfers to RBF should be based on past emission reductions in relation to a historical baseline, they hold clashing interpretations about temporal (i.e., past or future) and epistemological (i.e., how to measure) aspects of the results these payments are intended for. Firstly, while Brazil emphasizes that it deserves a reward of USD 21 billion for results achieved between 2006 and 2016, donor countries have indicated an interest in paying only for most recent results as a way to incentivize further reductions. Secondly, while all parties believe that Amazon Fund should support policies to reduce deforestation, donor countries have revealed concerns that the performance of the Amazon Fund projects in generating further reductions has not been measured in a rigorous manner. This suggests that donor countries may consider making changes to current RBF mechanisms or getting involved in new forms of finance.     

Sedimentary provenance in the central Ribeira belt based on laser-ablation ICPMSPb/Pb zircon ages

²⁰⁷Pb/²⁰⁶Pb ages from 420 zircons from 9 upper amphibolite and granulite facies quartzites of the post-1.8 Ga metasedimentary cover from the Occidental and Oriental terranes from the Neoproterozoic central Ribeira belt, in eastern Brazil, are discussed. Ages from the Occidental terrane show that Proterozoic ages predominate with a modal class at 2.1–2.2 Ga and that Archean ages are less common and lie within the 2.5–3.6 Ga range. A wider dispersion on Proterozoic ages down to 1.1 Ga and youngest Neoproterozoic ages (550–700 Ma) were also observed and could be related to the Brasiliano/PanAfrican metamorphic events. The data show that detrital sediments of the Occidental terrane were derived predominantly from erosion of a 1.8–2.2 Ga Paleoproterozoic terrane with a small proportion of a 2.6–3.6 Ga Archean crust. Ages from the Oriental terrane are greatly dispersed, but show a significant proportion of ages between 1.7 and 2.1 Ga, although the great majority are between 0.5 and 1.6 Ga. Only 3 out of 144 grains yield Archean ages, between 2.5 and 2.9 Ga. Based on the greatest errors observed on the data from the Oriental Terrane (100–300 Ma), and a continuum of obtained ages between 2072 Ma (Paleoproterozoic) and 517 Ma (Cambrian), the more plausible interpretation is that the dispersion of ages results from partial resetting of the U–Pb system by Brasiliano metamorphism in Proterozoic–Archean zircons, although a Mesoproterozoic source could not be discarded.     

Thermoluminescence, electron paramagnetic resonance and optical absorption in natural and synthetic rhodonite crystals

Thermoluminescence, electron paramagnetic resonance and optical absorption properties of rhodonite, a natural silicate mineral, have been investigated and compared to those of synthetic crystal, pure and doped. The TL peaks grow linearly for radiation dose up to 4 kGy, and then saturate. In all the synthetic samples, 140 and 340°C TL peaks are observed; the difference occurs in their relative intensities, but only 340°C peak grows strongly for high doses. Al₂O₃ and Al₂O₃ + CaO-doped synthetic samples presented several decades intenser TL compared to that of synthetic samples doped with other impurities. A heating rate of 4°C/s has been used in all the TL readings. The EPR spectrum of natural rhodonite mineral has only one huge signal around g = 2.0 with width extending from 1,000 to 6,000 G. This is due to Mn dipolar interaction, a fact proved by numerical calculation based on Van Vleck dipolar broadening expression. The optical absorption spectrum is rich in absorption bands in near-UV, visible and near-IR intervals. Several bands in the region from 540 to 340 nm are interpreted as being due to Mn³⁺ in distorted octahedral environment. A broad and intense band around 1,040 nm is due to Fe²⁺. It decays under heating up to 900°C. At this temperature it is reduced by 80% of its original intensity. The pink, natural rhodonite, heated in air starts becoming black at approximately 600°C.