XRF-scanned elemental concentrations from sediment cores off Peru

We present a high-resolution marine record of sediment input from the Guayas River, Ecuador, that reflects changes in precipitation along western equatorial South America during the last 18ka. We use log (Ti/Ca) derived from X-ray Fluorescence (XRF) to document terrigenous input from riverine runoff that integrates rainfall from the Guayas River catchment. We find that rainfall-induced riverine runoff has increased during the Holocene and decreased during the last deglaciation. Superimposed on those long-term trends, we find that rainfall was probably slightly increased during the Younger Dryas, while the Heinrich event 1 was marked by an extreme load of terrigenous input, probably reflecting one of the wettest period over the time interval studied. When we compare our results to other Deglacial to Holocene rainfall records located across the tropical South American continent, different modes of variability become apparent. The records of rainfall variability imply that changes in the hydrological cycle at orbital and sub-orbital timescales were different from western to eastern South America. Orbital forcing caused an antiphase behavior in rainfall trends between eastern and western equatorial South America. In contrast, millennial-scale rainfall changes, remotely connected to the North Atlantic climate variability, led to homogenously wetter conditions over eastern and western equatorial South America during North Atlantic cold spells. These results may provide helpful diagnostics for testing the regional rainfall sensitivity in climate models and help to refine rainfall projections in South America for the next century.

Relative abundances of sea ice-related abundances in sediment core NBP01-01-JPC24

Micropaleontological and biomarker data from two high-accumulation marine sites from the Coastal and Continental Shelf Zone (CCSZ) off East Antarctica (Adélie Land at w140°E and eastern Prydz Bay at w77°E) are used to reconstruct Holocene changes in sea ice and wind stress at the basin-wide scale. These data demonstrate congruent increase in sea-ice concentration/persistence and wind stress-related sea-surface turbulence in the two regions since 7 cal ka BP, with a particularly strong signal since 4.5 - 3.5 cal ka BP. Comparison of these high latitude records with sea ice and turbulence records from the southern mid-latitudes highlights distinctive climatic evolutions according to the different latitudinal bands. Sea-ice persistence and turbulence increase in East Antarctica CCSZ are opposite to sea-surface warming and sea-ice retreat recorded after 4.5 - 3.5 cal ka BP in the East Atlantic and Indian sector between 55 and 45°S. At the same period, paleodata suggest SST cooling in all major coastal upwelling systems of the southern hemisphere, caused by the northward transport of subpolar surface waters as a response to southern Westerlies reinforcement. We therefore propose, as suggested for the northern hemisphere, that Holocene changes in the latitudinal insolation gradient, primarily forced by obliquity and precession and amplified by sea-ice and glacial-ice expansions in the Antarctic realm, are responsible for the observed contrasted latitudinal patterns of southern latitudes.

Ratio of Diene/Triene of sediment core NBP01-01-JPC24

Micropaleontological and biomarker data from two high-accumulation marine sites from the Coastal and Continental Shelf Zone (CCSZ) off East Antarctica (Adélie Land at w140°E and eastern Prydz Bay at w77°E) are used to reconstruct Holocene changes in sea ice and wind stress at the basin-wide scale. These data demonstrate congruent increase in sea-ice concentration/persistence and wind stress-related sea-surface turbulence in the two regions since 7 cal ka BP, with a particularly strong signal since 4.5 - 3.5 cal ka BP. Comparison of these high latitude records with sea ice and turbulence records from the southern mid-latitudes highlights distinctive climatic evolutions according to the different latitudinal bands. Sea-ice persistence and turbulence increase in East Antarctica CCSZ are opposite to sea-surface warming and sea-ice retreat recorded after 4.5 - 3.5 cal ka BP in the East Atlantic and Indian sector between 55 and 45°S. At the same period, paleodata suggest SST cooling in all major coastal upwelling systems of the southern hemisphere, caused by the northward transport of subpolar surface waters as a response to southern Westerlies reinforcement. We therefore propose, as suggested for the northern hemisphere, that Holocene changes in the latitudinal insolation gradient, primarily forced by obliquity and precession and amplified by sea-ice and glacial-ice expansions in the Antarctic realm, are responsible for the observed contrasted latitudinal patterns of southern latitudes.

Geochemical biomarker analyses on sediment cores PS51/154-11 and PS51/159-10 from the western Laptev Sea (Arctic Ocean)

Multi-proxy biomarker measurements were applied on two sediment cores (PS51/154, PS51/159) to reconstruct sea ice cover (IP25), biological production (brassicasterol, dinosterol) and river run-off (campesterol, beta-sitosterol) in the western Laptev Sea over the last ~17 ka with unprecedented temporal resolution. The absence of IP25 from 17.2 to 15.5 ka, in combination with minimum concentration of phytoplankton biomarkers, suggests that the western Laptev Sea shelf was mostly covered with permanent sea ice. Very minor river run-off and restricted biological production occurred during this cold interval. From ~16 ka until 7.5 ka, a long-term decrease of terrigenous (riverine) organic matter and a coeval increase of marine organic matter reflect the gradual establishment of fully marine conditions in the western Laptev Sea, caused by the onset of the post-glacial transgression. Intensified river run-off and reduced sea ice cover characterized the time interval between 15.2 and 12.9 ka, including the Bølling/Allerød warm period (14.7-12.9 ka). Prominent peaks of the DIP25 Index coinciding with maximum abundances of subpolar foraminifers, are interpreted as pulses of Atlantic water inflow on the western Laptev Sea shelf. After the warm period, a sudden return to severe sea ice conditions with strongest ice-coverage between 11.9 and 11 ka coincided with the Younger Dryas (12.9-11.6 ka). At the onset of the Younger Dryas, a distinct alteration of the ecosystem (reflected in a distinct drop in terrigenous and phytoplankton biomarkers) was detected. During the last 7 ka, the sea ice proxies reflect a cooling of the Laptev Sea spring/summer season. This cooling trend was superimposed by a short-term variability in sea ice coverage, probably representing Bond cycles (1500 ± 500 ka) that are related to solar activity changes. Hence, atmospheric circulation changes were apparently able to affect the sea ice conditions on the Laptev Sea shelf under modern sea level conditions.

Preliminary results of ON/OFF detection using an integrated system for Parkinson's disease monitoring

This paper describes the experimental set up of a system composed by a set of wearable sensors devices for the recording of the motion signals and software algorithms for the signal analysis. This system is able to automatically detect and assess the severity of bradykinesia, tremor, dyskinesia and akinesia motor symptoms. Based on the assessment of the akinesia, the ON-OFF status of the patient is determined for each moment. The assessment performed through the automatic evaluation of the akinesia is compared with the status reported by the patients in their diaries. Preliminary results with a total recording period of 32 hours with two PD patients are presented, where a good correspondence (88.2 +/- 3.7 %) was observed. Best (93.7 por ciento) and worst (87 por ciento) correlation results are illustrated, together with the analysis of the automatic assessment of the akinesia symptom leading to the status determination. The results obtained are promising, and if confirmed with further data, this automatic assessment of PD motor symptoms will lead to a better adjustment of medication dosages and timing, cost savings and an improved quality of life of the patients.

Ireland gets the new Trio Presidency off to a propitious start. CEPS Commentary, 30 August 2013

The Irish Presidency of the Council of the EU (January-June 2013) faced numerous challenges, not least of which was to negotiate the financial framework for the period 2014-2020 and the reform of the Common Agricultural Policy with the European Parliament, as well as the pressure to advance the banking agenda. Moreover, the fact that it was the start of a new Trio Presidency, the small size of the Irish administration and its fragile financial situation gave rise to some doubts as to how much it could achieve. Nevertheless, this post mortem on the Irish presidency finds that the Irish government approached the task with realism and optimism, a firm focus on results and the strong conviction that a good performance would enhance its reputation at home and in the EU. It is now for Lithuania and subsequently Greece, in the first half of 2014, to continue to tackle the remaining formidable challenges.

Pollen abundance in Late Quaternary sediment cores off West Africa

The pollen record of three marine late Quaternary cores off Senegal shows a juxtaposition of Mediterranean, Northern Saharan, Central Saharan elements, which are considered transported by the trade winds from a winter-rainfall area, and Sahelian, Soudanese, Soudano-Guinean elements, considered transported both by winds and mostly by the Senegal River, and coming from the monsoonal, summer tropical rainfall area of southern West Africa. Littoral vegetation is either the edaphically dry and saline Chenopodiaceae from sebkhas at the time of the main regression, or the warm tropical humid mangrove with Rhizophora during the humid optimum period. Four stratigraphic zones reflect, from basis to top: Zone 4. A semi-arid period with a balanced pollen input. Zone 3. A very arid period with the disappearance of monsoonal pollen, probably from the disappearance of the Senegal River, a very saline littoral plain with Chenopodiaceae, a larger input of northern Saharan pollen from intensified trade winds. Zone 2. A quite humid period, much more so than today, very suddenly established, with a northward extension of the monsoonal areas, a rich littoral mangrove, and weakening of the trade winds. Zone l. A slow and steady evolution toward the present semi-humid conditions with regression of the mangrove, and of the monsoonal areas toward the south. Tentative datations and correlations with the Tchad area suggested: zone 4: 22,500 to 19,000 years BP; zone 3: 19,000 to 12,500 years BP; zone 2: 12,500 to 5,500 years BP; zone 1: 5,500 years BP to top of core. Dinoflagellate cysts display a tropical assemblage with mostly estuarine neritic elements and also a weak oceanic component, mostly in the lower slope core 47. Cosmopolitan taxa dominate the assemblage and only a few species point to more specialized environments. Quantitative variations of the assemblage are the basis of stratigraphy which is not similar to the pollen stratigraphy, and an inshore-outshore gradient has to be taken into account to correlate the three cores.

Sedimentological and paleomagnetic investigations on two gravity cores and ODP sites 113-690 and 693 off Kapp Norvegia, Antarctic continental margin

Oligocene to Quaternary sediments were recovered from the Antarctic continental margin in the eastern Weddell Sea during ODP Leg 113 and Polarstern expedition ANT-VI. Clay mineral composition and grain size distribution patterns are useful for distinguishing sediments that have been transported by ocean currents from those that were ice-rafted. This, in turn, has assisted in providing insights about the changing late Paleogene to Neogene sedimentary environment as the cryosphere developed in Antarctica. During the middle Oligocene, increasing glacial conditions on the continent are indicated by the presence of glauconite sands, that are interpreted to have formed on the shelf and then transported down the continental slope by advancing glaciers or as a result of sea-level lowering. The dominance of illite and a relatively high content of chlorite suggest predominantly physical weathering conditions on the continent. The high content of biogenic opal from the late Miocene to the late Pliocene resulted from increased upwelling processes at the continental margin due to increased wind strength related to global cooling. Partial melting of the ice-sheet occurred during an early Pliocene climate optimum as is shown by an increasing supply of predominantly current-derived sediment with a low mean grain size and peak values of smectite. Primary productivity decreased at ~ 3 Ma due to the development of a permanent sea-ice cover close to the continent. Late Pleistocene sediments are characterized by planktonic foraminifers and biogenic opal, concentrated in distinct horizons reflecting climatic cycles. Isotopic analysis of AT. pachyderma produced a stratigraphy which resulted in a calculated sedimentation rate of 1 cm/k.y. during the Pleistocene. Primary productivity was highest during the last three interglacial maxima and decreased during glacial episodes as a result of increasing sea-ice coverage.

Alkenone data of sediment core GeoB9508-5 from the continental slope off Senegal

In order to investigate a possible link between tropical Northeast (NE) Atlantic sea-surface temperature (SST), Atlantic meridional overturning circulation (AMOC), and drought in the Sahel during the past 44 thousand years (kyr) we used alkenone paleothermometry and d13C of C. wuellerstorfi of a marine sediment core from the continental slope off Senegal. Our data show periods of low SST and reduced AMOC that coincided with drought in the Sahel during North Atlantic Heinrich stadials (HS). The coldest period was HS1 (ca. 15-18 kyr before present, BP) when SST decreased by more than 2°C. Moreover, the SST off Senegal lagged variations in Sahel aridity, which is in agreement with results from a freshwater hosing experiment. We conclude that variations in tropical NE Atlantic SST were not the initial trigger of millennial-scale Sahel droughts of the past 44 kyr. Instead, it is thought that these droughts were induced by substantial coolings of the extratropical North Atlantic.