Ana Moreno

Orbital forcing of dust supply to the North Canary Basin over the last 250kyr

Abstract The Canary Basin lies in a region of strong interaction between the atmospheric and ocean circulation systems: Trade winds drive seasonal coastal upwelling and dust storm outbreaks from the neighbouring Sahara desert are the major source of terrigenous sediment. To investigate the forcing mechanisms for dust input and wind strength in the North Canary Basin, the temporal pattern of variability of sedimentological and geochemical proxy records has been analysed in two sediment cores between latitudes 30°30′N and 31°40′N. Spectral analysis of the dust proxy records indicates that insolation changes related to eccentricity and precession are the main periods of temporal variation in the record. Si/Al and grain-size of the terrigenous fraction show an increase in glacial–interglacial transitions while Al concentration and Fe/Al ratio are both in phase with minima in the precessional index. Hence, the results obtained show that the wind strength was intensified at Terminations. At times of maxima of Northern Hemisphere seasonal insolation, when the African monsoon was enhanced, the North Canary Basin also received higher dust input. This result suggests that the moisture brought by the monsoon may have increased the availability of dust in the source region.

Upwelling intensity and filament activity off Morocco during the last 250,000 years

Abstract The high-productive upwelling area off Morocco is part of one of the four major trade-wind driven continental margin upwelling zones in the world oceans. While coastal upwelling occurs mostly on the shelf, biogenic particles derived from upwelling are deposited mostly at the upper continental slope. Nutrient-rich coastal water is transported within the Cape Ghir filament region at 30°N up to several hundreds of kilometers offshore. Both upwelling intensity and filament activity are dependent on the strength of the summer Trades. This study is aimed to reconstruct changes in trade wind intensity over the last 250,000 years by the analysis of the productivity signal contained in the sedimentary biogenic particles of the continental slope and beneath the Cape Ghir filament. Detailed geochemical and geophysical analyses (TOC, carbonate, C/N, δ13Corg, δ15N, δ13C of benthic foraminifera, δ18O of benthic and planktic foraminifera, magnetic susceptibility) have been carried out at two sites on the upper continental slope and one site located further offshore influenced by the Cape Ghir filament. A second offshore site south of the filament was analyzed (TOC, magnetic susceptibility) to distinguish the productivity signal related to the filament signal from the general offshore variability. Higher productivity during glacial times was observed at all four sites. However, the variability of productivity during glacial times was remarkably different at the filament-influenced site compared to the upwelling-influenced continental slope sites. In addition to climate-related changes in upwelling intensity, zonal shifts of the upwelling area due to sea-level changes have impacted the sedimentary productivity record, especially at the continental slope sites. By comparison with other proxies related to the strength and direction of the prevailing winds (Si/Al ratio as grain-size indicator, pollen) the productivity record at the filament-influenced site reflects mainly changes in trade-wind intensity. Our reconstruction reveals that especially during glacial times trade-wind intensity was increased and showed a strong variability with frequencies related to precession.

Productivity response in the North Canary Basin to climate changes during the last 250 000 yr: a multi-proxy approach

We present results from the investigation of the primary productivity record over the last 250 kyr in the North Canary Basin (30°N) off Northwest Africa. Two distinct productive systems interfere in this area: the oligotrophic open ocean and the upwelling filament off Cape Ghir, that occasionally carries offshore cool nutrient-rich waters. The following geochemical and micropaleontological paleoproductivity proxies have been used in our study: calcium carbonate, barium excess (Baexcess), total organic carbon (TOC) and diatoms. Time series analysis of these proxies indicates that paleoproductivity in the North Canary Basin underwent important changes following precession and eccentricity cycles. While the precessional signal appears to be mainly related to trade wind strength, superimposed peaks in Baexcess, TOC and diatom records point to large productivity events at Terminations I, II and III. Lowering of the North Atlantic sea surface temperatures by melt water discharges which in turn strengthened the Azores high-pressure center and increased trade wind velocities is postulated as the mechanism to explain the enhancement of the coastal upwelling and associated filaments at terminations. Additionally, the Canary Current may play a role in transmitting cold melt waters and nutrients from higher latitudes to the North Canary Basin.

Hydrological change in Southern Europe responding to increasing North Atlantic overturning during Greenland Stadial 1

Significance This study presents robust evidence of two hydrological phases within the Greenland Stadial 1 (GS-1) cold event (12.8−11.7 ka B.P.) in Southern Europe. We present a well-dated high-resolution speleothem record (Seso Cave, Central Pyrenees) where temperature and hydrological signals are independently reconstructed. Detailed interpretation of stable isotopes and trace elements allow characterizing a first dry period followed, after 12,500 y before 2000 A.D., by more humid conditions. Our findings point to the resumption of the Atlantic overturning circulation as the main mechanism behind the hydrological response in Europe during this mid–GS-1 transition. The second phase, cold in Greenland but humid in Western Europe, represents a new paradigm in the well-established model of dry, cold stadials during the last glacial period. Greenland Stadial 1 (GS-1) was the last of a long series of severe cooling episodes in the Northern Hemisphere during the last glacial period. Numerous North Atlantic and European records reveal the intense environmental impact of that stadial, whose origin is attributed to an intense weakening of the Atlantic Meridional Overturning Circulation in response to freshening of the North Atlantic. Recent high-resolution studies of European lakes revealed a mid–GS-1 transition in the climatic regimes. The geographical extension of such atmospheric changes and their potential coupling with ocean dynamics still remains unclear. Here we use a subdecadally resolved stalagmite record from the Northern Iberian Peninsula to further investigate the timing and forcing of this transition. A solid interpretation of the environmental changes detected in this new, accurately dated, stalagmite record is based on a parallel cave monitoring exercise. This record reveals a gradual transition from dry to wet conditions starting at 12,500 y before 2000 A.D. in parallel to a progressive warming of the subtropical Atlantic Ocean. The observed atmospheric changes are proposed to be led by a progressive resumption of the North Atlantic convection and highlight the complex regional signature of GS-1, very distinctive from previous stadial events.

The Big’95 Debris Flow and Adjacent Unfailed Sediments in the NW Mediterranean Sea: Geotechnicalsedimentological Properties, and Dating

In this paper sedimentological, geotechnical, and age data from 7 piston cores of the continental slope and rise off the Ebro margin, North-western Mediterranean, are presented. The cores were obtained within and nearby an area that has undergone a major instability event occurred about 10 ka, known as the BIG’95. They show, at least, three distinct units, which are identified in relation to such event, namely a postlandslide, landslide and pre-landslide unit. Each one of these units shows distinct sedimentological and geotechnical characteristics interpreted in terms of depositional processes and consolidation history. The sedimentological and geotechnical data allows to infer that the BIG’95 is the result of a retrogressive slide and that the location of the channel levee complexes probably had a fundamental role in triggering the landslide, as well as controlling the location of the failure surface.

Innovative strategies minimize engraftment syndrome in multiple myeloma patients with novel induction therapy following autologous hematopoietic stem cell transplantation

Autologous stem cell transplantation (PBSCT) is standard for young patients in MM and its TRM has decreased after the 2000s. Bortezomib and immunomodulatory agents (IMiDs) in MM have improved the outcome. However, they seem to boost pro-inflammatory stage increasing the incidence of engraftment syndrome (ES). Favorable factors in PBSCT such as G-CSF could increase inflammatory stage during transplant. Corticosteroids have shown an excellent response of ES and some authors propose them as prophylaxis for ES. The aim was to analyze the impact of G-CSF avoidance and corticosteroids’ prophylaxis in 170 patients diagnosed of MM treated with bortezomib/IMiDs that underwent PBSCT. We established three groups: Group-I [(G-CSF_administration), 60 patients (35%)], group-II [(nonG-CSF), 60 patients (35%)] and group-III [(nonG-CSF plus corticosteroid’s prophylaxis), 50 patients (30%)]. A decreased ES incidence among groups was observed: 62, 42, and 22% (P < 0.0001). The incidence of symptoms mimicking a capillary leak syndrome associated with ES dropped: 43, 32, and 0% (P = 0.03). The G-CSF avoidance and corticosteroids had impact over admission 24, 21, and 20 days (P = 0.001). The most important variables related to ES were HCT-CI >2 (p < 0.0001; HR 8.5) and risk groups (p < 0.0001; HR 7.2). Hence, G-CSF avoidance and corticosteroid’s prophylaxis decrease morbidity in patients undergoing PBSCT with MM treated with bortezomib/IMiDs.