Water use efficiency of olive tree under two water treatments in Tunisian semi-arid conditions

Olive trees are grown under high evaporative demand and less precipitations that are variable in time and space especially in semi-arid conditions. The objective of this work is to determine the most efficient water treatment applied in an olive field (Olea europaea L. cv Chemlali) from the 98th to the 294th Julian day, in Tunisian semi-arid conditions. The choice of this time frame was done to control the effect of irrigation on the trees behavior in the irrigation period of the year (from April to October) and determine the most sensitive phenological stages to irrigation. For this reasons, two water treatments were applied: T100% (irrigation at 100% of Available Water Content (AWC)) and T50% (irrigation at 50% AWC). The results show that, according to leaf water potential, carbon isotope discrimination, and olive production parameters, the T50% AWC water treatment is the most efficient. The leaf water potential of the two water treatments applied has not exceeded ?2.5 MPa during the whole experiment which indicates that the trees of the two water treatments were not stressed. The T50% AWC shows a water use efficiency of 5.18 g/l compared to 2.93 g/l for T100% water treatment. This result demonstrate that Chemlali cultivar valorizes better low quantities of water rather than high quantities, so saving 50% of water resources applied will ensure the sustainability of water resources and stability of olive production.     

Seismic Imaging of Collapsed-Anticline Diapirs in Central Tunisia

Geotectonics - Central Tunisia is characterized by major fault systems, being ornamented by salt diapirs of the Late Triassic evaporite-rich interval. Salt movement began in the Late Triassic and...     

Mesozoic paleostress evolution in the Saharian platform (southern Tunisia)

Abstract

A detailed analysis of brittle deformations in the Saharian platform of southern Tunisia is based on studies of fault-slip data sets and joint sets. It allows reconstruction of the Mesozoic paleostress evolution. During the Permo-Triassic, N-S extensions occurred with high late Permian subsidence rates. During the Norian, strike-slip movements reactivated former normal faults. During the Jurassic and the Cretaceous a succession of extensional events was characterized by : (1) a N-S extension which dominated from late Triassic to early Aptian. We relate this extension to the Africa-Eurasia divergence; (2) a ENE-WSW extension during the Cenomanian. We relate this extension to the opening of «he African basins ; (3) a NE-SW Senonian extension that continued during the Cenozoic in the Jeffara and in the Gabes Gulf, during the further evolution of the northern African margin. The various compressional trends recorded in the platform are attributed to Cenozoic events.     

Changes of snow cover in Poland

The present paper examines variability of characteristics of snow cover (snow cover depth, number of days with snow cover and dates of beginning and end of snow cover) in Poland. The study makes use of a set of 43 long time series of observation records from the stations in Poland, from 1952 to 2013. To describe temporal changes in snow cover characteristics, the intervals of 1952–1990 and of 1991–2013 are compared and trends in analysed data are sought (e.g., using the Mann–Kendall test). Observed behaviour of time series of snow-related variables is complex and not easy to interpret, for instance because of the location of the research area in the zone of transitional moderate climate, where strong variability of climate events is one of the main attributes. A statistical link between the North Atlantic Oscillation (NAO) index and the snow cover depth, as well as the number of snow cover days is found.     

What can we learn from the projections of changes of flow patterns? Results from Polish case studies

River flow projections for two future time horizons and RCP 8.5 scenario, generated by two projects (CHASE-PL and CHIHE) in the Polish-Norwegian Research Programme, were compared. The projects employed different hydrological models over different spatial domains. The semi-distributed, process-based, SWAT model was used in the CHASE-PL project for the entire Vistula and Odra basins area, whilst the lumped, conceptual, HBV model was used in the CHIHE project for eight Polish catchments, for which the comparison study was made. Climate projections in both studies originated from the common EURO-CORDEX dataset, but they were different, e.g. due to different bias correction approaches. Increases in mean annual and seasonal flows were projected in both studies, yet the magnitudes of changes were largely different, in particular for the lowland catchments in the far future. The HBV-based increases were significantly higher in the latter case than the SWAT-based increases in all seasons except winter. Uncertainty in projections is high and creates a problem for practitioners.     

Richterite-bearing peridotites and MARID-type inclusions in lavas from North Eastern Morocco: mineralogy and D/H isotopic studies

 K-richterite/phlogopite-bearing peridotite xenoliths and MARID inclusions have been found in Late Cretaceous (67±0.2 million years) monchiquites and an olivine nephelinite from North Eastern Morocco. It is the first evidence of MARID rocks and K-richterite/phlogopite-bearing peridotites outside the kimberlitic context. In the hydrous xenoliths, textural features suggest that K-richterite, phlogopite and Al-poor diopside are replacement minerals. K-richterites contain 2–5 wt% FeO, 0.1–1.5 wt% TiO₂ and <0.5 wt% Cr₂O₃. Micas contain 5.4–7.4 wt% FeO and 0.3–2.2 wt% TiO₂, with Cr and Ni contents <0.2 wt%. Diopsides are Al-poor (<0.2 wt% Al₂O₃) and contain 0.1–0.2 wt% TiO₂, 0.9–1.1 wt% Na₂O and 1.3–1.7 wt% Cr₂O₃. Compared to known K-richterites and micas from metasomatised peridotite nodules (PKP types), the Moroccan minerals are more Fe rich, K-richterites have higher Ti and micas less Cr and Ni. They are thus closer to MARID than to PKP minerals. K-richterites and mica from the MARID inclusions show typical characteristics, e.g. high FeO (4.3–4.7 wt% in richterite and 7.2 wt% in mica), low NiO and/or Cr₂O₃ and the incomplete filling of the tetrahedral site by Si+Al. Ion probe D/H analyses of amphiboles and micas from both xenolith types give high δD values ranging from –8 to –73, with large variations within single grains (up to 50‰). Both the D-enrichment and the δD variations are inherited from the mantle. The similar chemical composition and δD values of K-richterite/phlogopite from the hydrous peridotites and MARID minerals suggest a genetic link between the two types of xenoliths. The conditions required for producing MARIDs and K-richterite/phlogopite-bearing peridotites may thus exist in contexts other than stable cratonic settings. MARID rocks and the associated metasomites may result from a hydrous fluid interaction with a peridotite, the metasomatic agent being characterised by a high K and low Al signature and a high δD value. A D-rich source is involved in the metasomatic event producing the hydrous minerals, and the scatter observed in the δD values suggests a mixing between this source and another one with typical upper mantle D/H composition. As indicated by the low δD (–74) values of micas from the host lava, metasomatism predated and is unrelated to the alkaline volcanism. Received: 9 March 1995 / Accepted: 4 April 1996     

Structure et caractérisation des matériaux utilisés dans la construction d'une mosaı̈que romaine de la cité de Volubilis (Maroc)

In Volubilis, Roman mosaics are very beautiful and reveal, from the bottom to the surface, three layers: (i) ‘hedgehog’ layer, (ii) coarse grain mortar layer (rudus + nucleus) and (iii) tesselatum. Mineralogical analysis of coarse grain mortar sampled in Flavius Germanus mosaic shows that it consisted of quartz and calcite, with some feldspar and probably mica and dolomite. Fine-grained mortar in tesselatum is made from a mixture of calcite and quartz only. Limestone tesserae (white, pink and brown) show petrographic facies that change from micritic to oolithic limestone. Conversely, black and brick red tesserae are respectively made of marble, red sandstone and from fire clay. Other colours as yellow, blue, green and grey are obtained from artificial glass with different chemical compositions. To cite this article: A. Dekayir et al., C. R. Geoscience 336 (2004).     

Geophysical approach for assessment of seawater intrusion in the coastal aquifer of Wadi Nador (Tipaza,Algeria)

The aquifer of Nador has suffered significant salinization due to seawater intrusion. It was strongly exploited during the 1980s and 1990s. A piezometric analysis in April 2012 showed the piezometric level to lie at 0 m a.s.l. over the plain; as a result, this aquifer is highly sensitive to the marine intrusion with an electrical conductivity of the groundwater in of exceeds 2500 μS/cm and so there are no abstractions for irrigation or drinking purpose from these sectors. The geoelectric study also showed the lateral variation in the electrical resistivity for two moments separated in time by more than 45 years. The fall in resistivity may be due to the encroachment of seawater into previously freshwater zones and/or infiltration during the era of pumped abstractions downstream. The resistivity surveys reveal two distinct sectors: the saturated aquifer in brackish and saltwater having resistivity values to 36-10 Ωm, which extends nearly 1600 m inland.     

Cs baseline levels in the Mediterranean and Black Sea: A cross-basin survey of the CIESM Mediterranean Mussel Watch programme

The common mussel Mytilus galloprovincialis was selected as unique biomonitor species to implement a regional monitoring programme, the CIESM Mediterranean Mussel Watch (MMW), in the Mediterranean and Black Seas. As of today, and upon standardization of the methodological approach, the MMW Network has been able to quantify ¹³⁷Cs levels in mussels from 60 coastal stations and to produce the first distribution map of this artificial radionuclide at the scale of the entire Mediterranean and Black Seas. While measured ¹³⁷Cs levels were found to be very low (usually <1 Bq kg⁻¹ wet wt) ¹³⁷Cs activity concentrations in the Black Sea and North Aegean Sea were up to two orders of magnitude higher than those in the western Mediterranean Basin. Such effects, far from representing a threat to human populations or the environment, reflect a persistent signature of the Chernobyl fallout in this area.     

Climate change impact on rainfall spatio-temporal variability (Macta watershed case,Algeria)

This work describes the climate change impact study on rainfall patterns in Macta watershed, located in the northwest of Algeria. The monthly rainfall data collection, verification and validation have built a database with 42 stations, each with 42 years of observations from 1970 to 2011. The study of annual total rainfall has identified a downward trend and quantifies the deficits that are within the observation time series. The division of the annual rainfall series into four periods allowed to highlighting the increase in inter-year temporal variability with the coefficient of variation increases from 17 to 27%. The study shows an annual rainfall deficit increment from 13 to 25%. The standard deviation values decrease significantly for the last two periods showing a spatial variability. Multivariate statistical study by the hierarchical clustering method resulted in the formation of station groups indicating the unification of monthly rainfall patterns.