Porosity and mineralogy evolution during the decay process involved in the Chellah monument stones

The objective of this work is to study the decay process involved in the historical Roman Chellah located in the Rabat city (Morocco). This monument is made up of porous calcarenite stone. Several samples, taken from altered and unaltered blocks, were analyzed by the water saturation, the mercury intrusion porosimetry techniques and using the scanning electron microscopy coupled to energy dispersive X-ray spectrometer (SEM–EDX). To perform a reliable chemical analysis, some samples were also analyzed by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The mercury porosimetry results show a bimodal porous network for this porous material, the deterioration process of these stones involved an increase in porous volume of about 2%. The lowest porosity observed in the unaltered block is connected to the presence of sparitic cement which causes a partial inter-granular porosity clogging. The highest porosity of the deteriorated block without crust is due to the increase in inter-granular space. SEM photographs of the unaltered sample show the presence of the porous primary grains, of ovoid forms and millimeter-length sizes, and of the secondary grains, of rhombohedric forms and micro size. Porosity is essentially located between the primary grains and can be completely clogged by secondary precipitations. Various forms of deterioration are observed on the altered samples such as the dissolution of the secondary grains edges, wells of dissolution and also the presence of argillaceous residues on the surface. This last was also detected by the ICP-AES and EDX analysis which show an increase of the silicon and aluminum contents toward the surface.     

Burgundy regional climate change and its potential impact on grapevines

ARPEGE general circulation model simulations were dynamically downscaled by The Weather Research and Forecasting Model (WRF) for the study of climate change and its impact on grapevine growth in Burgundy region in France by the mid twenty-first century. Two time periods were selected: 1970–1979 and 2031–2040. The WRF model driven by ERA-INTERIM reanalysis data was validated against in situ surface temperature observations. The daily maximum and minimum surface temperature (T_max and T_min) were simulated by the WRF model at 8?×?8?km horizontal resolution. The averaged daily T_max for each month during 1970–1979 have good agreement with observations, the averaged daily T_min have a warm bias about 1–2?K. The daily T_max and T_min for each month (domain averaged) during 2031–2040 show a general increase. The largest increment (~3?K) was found in summer. The smallest increments (<1?K) were found in spring and fall. The spatial distribution of temperature increment shows a strong meridional gradient, high in south in summer, reversing in winter. The resulting potential warming rate in summer is equivalent to 4.7?K/century under the IPCC A2 emission scenario. The dynamically downscaled T_max and T_min were used to simulate the grape (Pinot noir grape variety) flowering and véraison dates. For 2031–2040, the projected dates are 8 and 12?days earlier than those during 1970–1979, respectively. The simulated hot days increase more than 50% in the two principal grapevine regions. They show strong impact on Pinot noir development.     

Uncertainties in simulating regional climate of Southern Africa: sensitivity to physical parameterizations using WRF

This study aims at quantifying seasonal biases of regional climate model outputs during southern African summer, against a dense in situ measurement network (daily rain-gauge and surface air temperature records, and 12?h UTC radiosondes), and uncertainties associated with some physical parameterizations. Using the non-hydrostatic Advanced Research Weather Forecast (WRF) laterally forced by ERA40 reanalysis, twenty-seven experiments configured with three schemes of cumulus (CU), planetary boundary layer (PBL) and microphysics (MP), are performed at 35?km horizontal resolution during the core of a summer rainy season (December 1993 to February 1994 season) representative of the South African rainfall climatology. WRF simulates accurately seasonal large-scale rainfall patterns, as well as seasonal gradients of South African rainfall and 2-m temperature, and seasonal vertical profiles of the air temperature and humidity. However seasonal biases fluctuate strongly from an experiment to another, denoting considerable uncertainties generated by the physical package. Rainfall amounts are the most sensitive parameter to the tested schemes. Their geography, intensity, and intraseasonal characteristics are predominantly sensitive to CU schemes, and much less to PBL and MP schemes. Some CU-PBL combinations produce additive effects, which can dramatically either reduce or increase biases. Satisfactory configurations are found for South African climate, which would not have been possible without testing numerous physical parameterizations.     

Thermo‐tectonic evolution of the south‐central Pyrenees from rifting to orogeny: insights from detrital zircon U/Pb and (U‐Th)/He thermochronometry

Constraining the thermal and denudational evolution of continental margins from extensional episodes to early orogenic stages is critical in the objective to better understand the sediment routing during the growth of orogenic topography. Here, we report 160 detrital zircon U/Pb ages and 73 (U‐Th)/He ages from Albian, Upper Cretaceous and Eocene sandstones from the south‐central Pyrenees. All samples show dominant zircon U/Pb age peaks at 310–320 Ma, indicating a primary contribution from Variscan granites of the central Pyrenean Axial Zone. A secondary population at 450–600 Ma documents zircon grains sourced from the eastern Pyrenees. Zircon (U‐Th)/He ages recovered from older samples document, a Triassic age peak at ca. 241 Ma, corresponding to denudation coeval with the initiation of Atlantic rifting. An Early Cretaceous cooling event at ca. 133 Ma appears consistent with rift‐related exhumation and thermal overprint on the Iberian margin. The (U‐Th)/He age peaks from ca. 80 Ma to ca. 68 Ma with decreasing depositional ages are interpreted to reflect the southward‐migrating thrust‐related exhumation on the pro‐wedge side of the Pyrenean orogen. The increase in lag times, from ca. 15 Ma in the Tremp Formation (ca. 65 Ma) to 28 Ma in the Escanilla Formation (ca. 40 Ma), suggests decreasing exhumation rates from 0.4 km Myr^–1 to 0.2 km Myr^–1. The apparent inconsistency with convergence rates is used to infer that rocks cooled at 68 Ma may have resided in the crust before final exhumation to the surface. Finally, the cooling event observed at 68 Ma provides support to the inferred acceleration of convergence, shortening and exhumation during Late Cretaceous times.     

High Resolution DEM Generation in High‐Alpine Terrain Using Airborne Remote Sensing Techniques

Up‐to‐date and accurate digital elevation models (DEMs) are essential for many applications such as numerical modeling of mass movements or mapping of terrain changes. Today the Federal Department of Topography, swisstopo, provides Digital Terrain Models (DTMs) and Digital Surface Models (DSMs) derived from airborne LiDAR data with a high spatial resolution of 2 m covering the entire area of Switzerland below an elevation of 2000 m a.s.l.. However, above an elevation of 2000 m a.s.l., which is typical for high‐alpine terrain, the best product available is the a DTM with a spatial resolution of 25 m. This spatial resolution is insufficient for many applications in complex terrain. In this study, we investigate the quality of DSMs derived from opto‐electronic scanner data (ADS80; acquired in autumn 2010) using photogrammetric image correlation techniques based on the multispectral nadir and backward looking sensor data. As reference, we take a high precision airborne LiDAR data set with a spatial resolution of ca. 0.5 m, acquired in late summer 2010, covering the Grabengufer/Dorfbach catchment near Randa, VS. We find the deviations between the two datasets are surprisingly low. In terrain with inclination angles of less than 30° the RMSE is below 0.5 m. In extremely steep terrain of more than 50° the RMSE goes up to 2 m and outliers increase significantly. We also find dependencies of the deviations on illumination conditions and ground cover classes. Finally we discuss advantages and disadvantages of the different data acquisition methods.     

Reviews

CUL DE SAC: The Question of New Zealand's Future by H. Franklin. 13 x 19 cm, 184 pages. Allen & Unwin: Sydney 1985 (ISBN 0 86861 514 5) $A12.95 (soft).

SHOPPING CENTRE DEVELOPMENT: Policies and Prospects edited by J. A. Dawson and J. D. Lord. 14 x 22 cm, 269 pages. Croom Helm: London 1985 (ISBN 0 7099 0845 8) $A49.95 (hard).

GENTRIFICATION OF THE CITY edited by N. Smith and P. Williams. 13 x 22 cm, xiii and 257 pages. Allen & Unwin: Boston 1986 (ISBN 0 04 301201 9) $A59.00 (hard); (ISBN 0 04 301202 7) $A26.95 (soft).

EUROPE TODAY: Countries and Issues by D. J. Davis and D. C. Flint. 19 x 27 cm, 256 pages. Bell & Hyman: London 1986 (ISBN 0 7135 2518 5) £5.95 (soft).

THE WORLD NOW (Australian edition) by A. Reed and R. Pask. 21 x 30 cm, 96 pages. Edward Arnold: Melbourne 1986 (ISBN 0 7131 8225 3) $A12.95 (soft).

THE INDO‐PACIFIC LIBRARY: Set Two — Ten Titles (11 Australia, 12 Burma, 13 French Polynesia, 14 India, 15 Laos and Kampuchea, 16 North and South Korea, 17 Pakistan and Bangladesh, 18 Sri Lanka, 19 Thailand, 20 Vietnam) by G. Houghton and J. Wakefield. 19 x 25 cm, 32 pages each. Macmillan: Melbourne 1987 $A9.95 (hard) each title.

THE INDO‐PACIFIC LIBRARY: Set Two — Macmillan Black Line Masters by G. Houghton and J. Wakefield. Macmillan: Melbourne 1987 (ISBN 0 333 43059 X) $A19.95 (soft).

QUEENSLAND: A Geographical Interpretation (Queensland Geographical Journal, 4th Series, Volume 1) edited by J. H. Holmes. 18 x 24 cm, 343 pages. Boolarong Publications: Brisbane 1986 (ISBN 0817 489X) $A25.00 (soft).

THE ROAD TO BOTANY BAY: An Essay in Spatial History by P. Carter. 14 x 22 cm, xv and 384 pages. Faber and Faber: London 1987 (ISBN 0 571 14551 5) $A29.95 (hard).

AN EVALUATION OF LOCAL AREA ECONOMIC STRATEGY STUDIES (Australian Regional Developments, No. 6) edited by J. D. Conroy. 30 x 21 cm, vii and 102 pages. Australian Government Publishing Service: Canberra 1987 (ISBN 0 644 06161 8).

PRODUCTION, WORK, TERRITORY: The Geographical Anatomy of Industrial Capitalism edited by A. J. Scott and M. Storper. 15 x 23 cm, xix and 344 pages. Allen & Unwin Inc: Boston 1986 (ISBN 0 04 338126 X) $A90.00 (hard); (ISBN 0 04 338127 8) $A38.95 (soft).

ANALYTICAL BEHAVIOURAL GEOGRAPHY by R. G. Golledge and R. J. Stimson. 16 x 24 cm, 345 pages. Croom Helm: London 1987 (ISBN 0 7099 3844 6) $A122.95 (hard).

AMBIGUOUS ALTERNATIVE: Tourism in Small Developing Countries edited by S. Britton and W. C. Clarke. 20 x 21 cm, 194 pages. University of the South Pacific: Suva 1987 (ISBN 982 01 0009); available from Geography Department, University of the South Pacific, Box 1168, Suva, Fiji.

AN ATLAS OF ENVIRONMENTAL AND RUMINANT POPULATION CHARACTERISTICS OF JAVA: A Multivariate Analysis Approach by J. M. Perkins, Armiadi Semali, P. W. Orchard and Rach‐met Rachman. 46 x 31 cm, 71 pages. Forage Research Project, University of New England: Armidale 1986 (ISBN 0 85834 691 5) $A50.00 plus postage (developed countries); $A20.00 plus postage (developing countries).

ANTARCTICA: THE NEXT DECADE. Report of a Study Group (Studies in Polar Research) by A. Parsons et al. 15 x 23 cm, xii and 164 pages. Cambridge University Press: Cambridge 1987 (ISBN 0521 331811) $A65.00 (hard).

THE HUMAN IMPACT ON THE NATURAL ENVIRONMENT by A. Goudie, 25 x 17 cm, x and 338 pages. Basil Blackwell: Oxford 1986 (ISBN 0 631 13758 0) $A29.50 (soft).

ATMOSPHERIC POLLUTION: Causes, Effects and Control Policies by D. Elsom. 15 x 23 cm, x and 319 pages. Basil Blackwell: Oxford 1987 (ISBN 0 631 13813 3) $A122.50 (hard); (ISBN 0 631 15674 7) $A43.95 (soft).

SEA SURFACE STUDIES: A Global View edited by R. J. N. Devoy. 16 x 24 cm, 649 pages. Croom Helm: London 1987 (ISBN 0 7099 0871 7) £55.00 (hard).     

Chemical characteristics of groundwater around two massive sulphide deposits in an area of previous mining contamination, Iberian Pyrite Belt, Spain

A detailed chemical study of groundwater was carried out to elucidate the processes controlling the oxidation and dissolution of sulphide minerals at two massive sulphide deposits in the Iberian Pyrite Belt (IPB), i.e. the mined La Zarza deposit and the unmined Masa Valverde deposit. It was found that major-element compositions varied according to the hydrological regime, La Zarza being in a relatively high area with groundwater recharge (and disturbance due to the human factor) and Masa Valverde being in a relatively low area with groundwater discharge. The variations mainly concern pH, Eh, SO₄ and Na concentrations. Metal concentrations were determined (a) by ICP-MS after filtration, and (b) in some cases by voltammetric measurement of Cu, Pb, Zn, Cd and Mn using the Voltammetric In situ Profiling (VIP) System, which allows detection of only the mobile fractions of trace elements (i.e., free metal ions and small labile complexes a few nanometers in size). If one compares the results obtained by each of the two methods, it would appear that the groundwater shows significant enhancement of metal solubility through complexing with organic matter and/or adsorption onto colloids and/or small particles. In areas of sulphide oxidation, however, this solubility enhancement decreases according to Cu>Zn>Cd>Pb. Under very low redox conditions, the attained metal concentrations can be several orders of magnitude (up to 10⁸–10⁹ for Cu and 10²–10³ for Pb) larger than those expected from equilibrium with respect to sulphide minerals as calculated with the EQ3NR geochemical code; Zn concentrations, however, are close to equilibrium with respect to sphalerite. The implication of these results is discussed with respect both to mineral exploration and to environmental issues.     

Solute transfer across the sediment surface of a eutrophic lake: I. Porewater profiles from dialysis samplers

Porewater profiles often are used to identify and quantify important biogeochemical processes occurring in lake sediments. In this study, multiple porewater profiles were obtained from two eutrophic Swiss lakes using porewater equilibrators (peepers) in order to examine spatial and seasonal trends in biogeochemical processes. Variability in profile shapes and concentrations was small on spatial scales of a few meters, but the uncertainty in calculated diffusive fluxes across the sediment surface was, on average, 35%. Focusing of Fe and Mn oxides toward the lake center resulted in systematic increases in porewater concentrations and diffusive fluxes of Fe²⁺ and Mn²⁺ with increasing water depth; these fluxes are postulated to be regulated by the pH-dependent dissolution of reduced-metal phases. Despite higher concentrations of inorganic carbon, NH ₄ ⁺ , Si and P in pelagic compared to littoral sites, diffusive fluxes of these substances across the sediment surface increased only slightly or not at all with increasing water depth. Porewater profiles did reveal temporal changes in Fe²⁺, Mn²⁺, Ca²⁺ and Mg²⁺ that were an indirect result of the large, seasonal changes in seston deposition, but no clear seasonal variations were found in diffusive fluxes of nutrients across the sediment surface. The intense mineralization occurring at the sediment surface was not reflected in the porewater profiles nor in the calculated diffusive fluxes. Calculated diffusive fluxes across the sediment surface resulted from decomposition occurring primarily in the top 5–7 cm of sediment. Diffusive fluxes from this subsurface mineralization were equal to the solute release from mineralization occurring at the sediment-water interface. Buried organic matter acts as a memory of previous lake conditons; it will require at least a decade before reductions in nutrient inputs to lakes fully reduce the diffusive fluxes into the lake from the buried reservoir of organic matter.