Ventifacts distribution in Qatar

This study attempts to investigate the distribution of ventifacts in Qatar. It is believed that ventifacts are confined to the areas within about 5 km of the Miocene or Mio-Pliocene Hofuf formations and the spreads of continental gravels derived from them. Three hypotheses were formulated: (1) Ventifacts in Qatar are confined to areas within about 5 km of the Hofuf formations and the spreads of continental gravels derived from them. The distribution of ventifacts within these areas varies according to the nature of the ground surface; (2) The most active ventifaction areas are where the continental gravels merge with the Eocene limestone because of the increase in saltation particle speed in these areas where bedrock or bare limestone is exposed; (3) The unit area ratio of ventifact to non-ventifact pebbles varies inversely with the total amount of pebbles. To test these hypotheses, nine land class categories were identified in the three major Hofuf formations. Line transects were carried out from randomly selected stations near the middle of the Hofuf formations. Along each transect systematic sampling was carried out at 200 m intervals. The data were processed using a WANG MVP 2200 computer with software developed for the project. It was found that ventifacts tend to concentrate on the outer edges of the continental gravels in areas of limestone outcrop and limestone pavement. Higher areas have big gravel counts and a low ratio of ventifacts while the low-lying plains have small gravel counts and a higher ratio of ventifacts. In certain areas ‘ventifact fields’ were found where the density of ventifacts was as high as 30 per m². Many of the ventifacts in these fields were buried beneath the surface suggesting that the ventifaction predates the present site conditions. Other high ventifact density areas were discovered where the ventifacts have collected in shallow depressions or hollows on the limestone plateaux. Water action has washed these ventifacts, a high proportion of which are dreikanters, into the hollows, where they have been partially buried in fine alluvial silts. These ‘ventifact graveyards’ are generally only a few metres wide but contain large numbers of fine specimens.     

Calculated geochronology and stress field orientations along the Hawaiian chain

A new method has been discovered for calculating ages of the main shield building stages of volcanoes along the Hawaiian chain from Kilauea to the Hawaiian-Emperor bend. The method is based on a graphical technique for hypothetical subtraction of distance intervals that theoretically represent regions of simultaneous volcanism along adjacent or nearly en-echelon loci of volcanism. Distances along the chain, measured from Kilauea, when progressively foreshortened by the distances of hypothetical “collapse” and plotted versus existing age data are found to give linear age-distance relationships. A calibration graph is presented that agrees closely with the measured ages in 17 of the 20 existing dated volcanoes. The criterion for simultaneous activity on different loci is based on the concept of equal azimuths of synchronous volcanic propagation within coeval segments of the chain. This is the predicted relationship when magmatic fluids inject the lithosphere along directions normal to a nearly horizontal least principal stress. It appears that the Pacific plate has been subjected to oscillatory, but principally clockwise, rotations of horizontal stress components during the last 40 m.y.     

Release of volatile mercury from soils and non-vascular plants

Vegetation plays a significant role in the biogeochemical cycling of mercury. This conclusion is drawn from data presented here on bioaccumulation and subsequent release of volatile mercury from non-vascular plants together with the results of previous work. There is no obvious relation between total plant Hg or soil Hg and rate of release from the plant. Heat of vaporization for Hg⁰ was calculated at 13.99 kcal/g-atom; from soil it was experimentally determined at 13.81 kcal/g-atom but from the most active vascular plant was only 9.49 kcal/g-atom.     

Oxygen isotopic ratios in fine quartz silt from sediments and soils of southern Africa

Fine quartz silt (1–10μm dia, important in aerosol dust) isolated from a large number of soils, as well as Phanerozoic shales, sandstones and recent sands of the southern African stratigraphie column (Carboniferous, Permian and Triassic) exhibits a mean δ¹⁸O of 12.2 ± 2.1%0. These values are similar to those reported for South Pacific pelagic sediments and adjacent land areas of similar latitude but are lower than those reported for this size fraction of 30 Mesozoic and Paleozoic shales (20.7 ± 1.8%.) and soils from mid-continental U.S.A., for aerosol quartz in the North Pacific pelagic sediments, and for eolian caps in high-elevation soils of Hawaii. The lower oxygen isotopic ratios in fine quartz silt of southern Africa reinforces the earlier indication that Southern Hemisphere detritai sedimentary reservoirs contain a higher proportion of igneous and metamorphic quartz (lower δ¹⁸O) and less lowtemperature authigenic quartz (higherδ¹⁸O) than Northern Hemisphere detritai sediments. The difference reflects climates, as continents drifted in latitude.     

Earth observations for sustainable development goals monitoring based on essential variables and driver-pressure-state-impact-response indicators

ABSTRACT

In recent years, researchers of different communities have increased their efforts in formalizing a set of measurements regularly collected for analysing changes in Drivers, States, Impacts and Responses of a given discipline. In some cases, different actors have converged in a minimum set of Essential Variables (EVs), such as for Climate, Biodiversity or Oceans. The definition of such EVs is an ongoing evolution and in extension (e.g. EVs for water) although some communities have not even started (e.g. agriculture and energy). This paper characterizes the Earth Observation (EO) networks and creates a graph representation of their relations. Secondly, this graph is enriched with the EVs produced by each network creating a knowledge base. Finally, an effort has been done to identify links between EVs and Sustainable Development Goals (SDG) indicators in a way that they indirectly connect the EO. An analysis to detect gaps in EO variables due to a lack of observational networks is performed. Several suggestions for improving SDG indicators framework by considering EVs are exposed, as well as proposing new necessary EVs and suggesting new EO based indicators. The complete graph is available in the ENEON website (http://www.eneon.net/graph-ev-sdg/).     

Towards integrated essential variables for sustainability

ABSTRACT

Measuring the achievement of a sustainable development requires the integration of various data sets and disciplines describing bio-physical and socio-economic conditions. These data allow characterizing any location on Earth, assessing the status of the environment at various scales (e.g. national, regional, global), understanding interactions between different systems (e.g. atmosphere, hydrosphere, biosphere, geosphere), and modeling future changes. The Group on Earth Observations (GEO) was established in 2005 in response to the need for coordinated, comprehensive, and sustained observations related to the state of the Earth. GEO’s global engagement priorities include supporting the UN 2030 Agenda for Sustainable Development, the Paris Agreement on Climate, and the Sendai Framework for Disaster Risk Reduction. A proposition is made for generalizing and integrating the concept of EVs across the Societal Benefit Areas of GEO and across the border between Socio-Economic and Earth systems EVs. The contributions of the European Union projects ConnectinGEO and GEOEssential in the evaluation of existing EV classes are introduced. Finally, the main aim of the 10 papers of the special issue is shortly presented and mapped according to the proposed typology of SBA-related EV classes.     

Study of the interaction between U(VI) and the anoxic corrosion products of carbon steel

The objective of this study was to investigate the removal mechanism of U(VI) from groundwater by magnetite as the main product of anoxic steel corrosion. For this purpose, a systematic sequence of batch experiments was conducted to focus the active role of magnetite in the reduction of U under different conditions. Results indicated that under anoxic conditions U(VI) was sorbed at the magnetite surface, whereas under reducing conditions at different H₂(g) pressures, U was present in tetravalent form as amorphous UO₂.     

Synthesis and Preliminary Characterisation of New Silicate, Phosphate and Titanite Reference Glasses

Eleven synthetic silicate and phosphate glasses were prepared to serve as reference materials for in situ microanalysis of clinopyroxenes, apatite and titanite, and other phosphate and titanite phases. Analytical results using different micro-analytical techniques showed that the glass fragments were homogeneous in major and trace elements down to the micrometre scale. Trace element determinations using inductively coupled plasma-mass spectrometry (ICP-MS), multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS), laser-ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) and secondary ionisation mass spectrometry (SIMS) showed good agreement for most elements (Li, Be, B, Cs, Rb, Ba, Sr, Ga, Pb, U, Th, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Er, Tm, Yb, Lu, Zr, Hf, Ta, Nb) studied and provide provisional recommended values.     

A coastal reservoir of terrestrial resources for neanderthal populations in north‐eastern Iberia: palaeoenvironmental data inferred from the small‐vertebrate assemblage of Cova del Gegant,Sitges, Barcelona

Coastal areas as reservoirs of resources for hominid groups have been widely studied in recent years. These areas combine marine with terrestrial and wetland resources and would have been optimum sites for hominids, including Neanderthals. This is the case with the Cova del Gegant, a cave that today opens directly onto the Mediterranean Sea and is located in the north‐eastern Iberian Peninsula. The geomorphological evolution of the Massis del Garraf has provided evidence that during the late Pleistocene there was a littoral platform between 8 and 13 km wide in front of the Cova del Gegant. Within this framework, the data derived from analysis of the small vertebrates and large mammals recovered from Cova del Gegant, including taxa currently absent from the Massis del Garraf, suggest that the landscape surrounding the cave provided a richer terrestrial ecosystem for Neanderthals than is available in this zone today. Analysis of the small‐vertebrate association from the cave reveals that the landscape surrounding the cave was dominated by woodland‐edge and open environments and that the climate was Mediterranean. The results have been compared with the only Iberian site with similar characteristics to the Cova del Gegant, Gorham's cave (southern Iberia, Gibraltar), revealing differences and similarities in the landscape and climate on the basis of the small‐mammal assemblages as well as the differences in the accessibility to terrestrial mammalian resources for the Neanderthal groups. The landscape and the climate were reasonably similar at the two sites, but the differences in the accessibility of resources for the Neanderthals are directly related to the location of the sites and the coastal position. Whereas the Cova del Gegant was on a route of mammal migration (between the Ebro Valley and France) suited for securing terrestrial resources, Gorham's cave is located on a small peninsula with a lower abundance of terrestrial mammal resources. This is probably why the Neanderthal groups at Gorham's cave exploited marine resources, whereas there is no evidence of marine resources having been exploited at Cova del Gegant, even though the seashore was nearby. Copyright © 2011 John Wiley & Sons, Ltd.