Ice-rafted debris record in the Prydz Bay

Ice-rafted debris mass accumulation rates (IRD MAR) at a drill site on the Antarctic continental margin are investigated to evaluate the linkages between East Antarctic Ice Sheet extent and Southern Ocean temperatures in the early to mid-Pliocene. ODP Site 1165 is within 400 km of the Antarctic coastline and in the direct pathway of icebergs released by the Amery Ice Shelf. The Amery Ice Shelf is the largest ice shelf in East Antarctica and it buttresses the Lambert Glacier drainage system, which accounts for 14% of the outflow from the East Antarctic Ice Sheet. IRD MAR were low during peak Southern Ocean warming in the early Pliocene. After a brief precursor, a tenfold increase in IRD MAR at 3.3 Ma marks the termination of the early Pliocene ice sheet minimum, coincident with the M2 glacial. For the mid-Pliocene, a strong correlation exists between the high-amplitude signal in the LR04 benthic stack and IRD MAR, suggesting linkages between East Antarctic ice extent, global ice volume and deep-water temperatures. The IRD record at Site 1165 provides evidence of greater sensitivity of the Lambert Glacier-Amery Ice Shelf system to Southern Ocean warming than is currently predicted by ice sheet models, which may relate to uncertainties in the understanding of ocean heat uptake, poleward heat transport and ice sheet-ocean interactions.

Composition and fluxes of sinking particulate material and bottom sediments in the northeast Black Sea in 1998-1999

For the first time deep-sea mooring stations with sediment traps were deployed in the northeast Black Sea. One sediment trap for long-term studies was located at Station 1 (44°15'N, 37°43'E, deployment depth 1800 m, depth 1900 m). The trap collected sinking sedimentary material from January to May 1998. Material collectors were changed every 15 days. Other stations with sediment traps for short-term studies (September-October 1999) were located on the shelf: Station 2 (44°16'N, 38°37'E, deployment depth 45 m, depth 50 m) and on the bottom of the canyon: Station 3 (44°16'N, 38°22'E, deployment depth 1145 m, depth 1150 m), Station 4 (44°11'N, 38°21'E, deployment depths 200, 1550, 1650 m, depth 1670 m). Collected material indicates that vertical particle fluxes are controlled by seasonal changes of in situ production and by dynamics of terrigenous matter input. Higher vertical particle flux of carbonate and biogenic silica was in spring due to bloom of plankton organisms. Maximum of coccolith bloom is in April-May. Bloom of diatoms begins in March. In winter and autumn lithogenic material dominates in total flux. Its amount strongly depends on storms and river run-off. Suspended particle material differs from surface shelf sediments by finer particles (mainly clay fraction) and high content of clay minerals and biogenic silica. This material may form lateral fluxes with higher concentration of particles transported along the bottom of deep-sea canyons from the shelf to the deep basin within the nepheloid layer. In winter such transportation of sedimentary material is more intensive due to active vertical circulation of water masses.

Plant height along the plant diversity gradient in the Jena Experiment (Main Experiment, year 2002)

This data set contains measurements of plant height: vegetative height (non-flowering indviduals) and regenerative height (flowering individuals) in 2002 from the Main Experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the Main Experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. In 2002, plant height was recorded twice a year: in late June and just before biomass harvest during peak standing biomass in late August. For 3 target plant individuals (if present) per sown species from the central area of the plots, vegetative height (non-flowering indviduals) and regenerative height (flowering individuals) were measured as stretched height. Provided are the indivdiual measurements and the mean over the measured plants per plot (in June) and the mean over the measured plants per plot (in August).

Organic carbon accumulation in the equatorial Atlantic

Organic geochemical records of the last 940 kyr are presented for equatorial Atlantic Ocean Drilling Program (ODP) sites 663 and 664 and discussed with regard to the development of ocean productivity and African paleoclimate. Proportions of marine and terrigenous organic matter (OM) are estimated from elemental, pyrolytic, isotopic, and petrologic data. Spectral analyses reveal a strong power at the eccentricity and obliquity band, indicating a close response of tropical organic sedimentation to the climatic evolution at high latitudes. The orbital covariance of organic carbon with biogenous opal and terrigenous records favor that glacially enhanced dust supply and surface water mixing were primary controls for deposition of organic carbon. Wind-borne supply of terrigenous OM contributes 26 to 55% and 0 to 39% to the bulk OM based on microscopic and isotopic records, respectively. Admixture of C4 plant matter was approximated to contribute up to 16% to the bulk organic fraction during peak glacial conditions.

Ostracode fauna of sediment core GIK23414-9 in the northeast Atlantic

Sediment core M23414 from the Rockall Plateau (North Atlantic) covering the last two climatic cycles, marine isotope stages (MIS) 7 to 1, was investigated for glacial-interglacial variations in the deep-sea benthic ostracode fauna. A highly diversified ostracode fauna including 98 species was found. Two climate-related assemblages were identified, associated with interglacial and peak glacial periods, respectively. The 'interglacial' group occurs during the end of MIS 7, 5 and 1 and is composed of the genera Henryhowella, Pelecocythere, Echinocythereis, Cytherella, Bradleya, Aversovalva and Eucytherura. The 'glacial' group consists of the genera Acetabulastoma (which is known as 'sea ice indicator' in the modern Arctic Ocean), Polycope, Bythoceratina, ?Rhombobythere, and some species possibly belonging to the genus Pseudocythere and is found during MIS 6, 4 and 2. These longer-term variations within the ostracode fauna seem related to the particular glacial and interglacial climate conditions that affected both deep-water production as well as primary production in the surface waters. However, a detailed comparison of ostracode abundances with the occurrence of events marked by increased ice-rafted debris reveals also much shorter-term climate related changes in the ostracode fauna. Thus, the temporal fluctuations within ostracode assemblages reflect long- and short-term alterations of the deep-sea environment that are clearly linked to climate changes.

Collection of data on particulate and dissolved soil phosphorus in the Jena Experiment (Main Experiment, time series since 2002)

This data set contains two time series of measurements of dissolved phosphorus (organic, inorganic and total with a biweekly resolution) and dissolved inorganic phosphorus with a seasonal resolution. In addition, data on phosphorus from soil samples measured in 2007 and fractionated by different acid-extrations (Hedley fractions) are provided. All data measured at the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. 1. Dissolved phosphorus in soil solution: Suction plates installed on the field site in 10, 20, 30 and 60 cm depth were used to sample soil pore water. Cumulatively extracted soil solution was collected every two weeks from October 2002 to May 2006. The biweekly samples from 2002, 2003 and 2004 were analyzed for dissolved organic phosphorus (DOP), dissolved inorganic phosphorus (PO4P) and dissolved total phosphorus (TDP) by Continuous Flow Analyzer (CFA SAN ++, SKALAR [Breda, The Netherlands]). 2. Seasonal values of dissolved inorganic phosphorus in soil solution were calculated as volume-weighted mean values of the biweekly measurements (spring = March to May, summer = June to August, fall = September to November, winter = December to February). 3. Phosphorus fractions in soil: Five independent soil samples per plot were taken in a depth of 0-15 cm using a soil corer with an inner diameter of 1 cm. The five samples per plot were combined to one composite sample per plot. A four-step sequential P fractionation (Hedley fractions) was applied and concentrations of P fractions in soil were measured photometrically (molybdenum blue-reactive P) with a Continuous Flow Analyzer (Bran&Luebbe, Germany).

Nutrient concentration profiles from time series stations E1 and L4 in the western English Channel from 2000 to 2010

The marine laboratories in Plymouth have sampled at two principle sites in the Western English Channel for over a century in open-shelf (station E1; 50° 02'N, 4° 22'W) and coastal (station L4; 50° 15'N, 4° 13'W) waters. These stations are seasonally stratified from late-April until September, and the variable biological response is regulated by subtle variations in temperature, light, nutrients and meteorology. Station L4 is characterized by summer nutrient depletion, although intense summer precipitation, increasing riverine input to the system, results in pulses of increased nitrate concentration and surface freshening. The winter nutrient concentrations at E1 are consistent with an open-shelf site. Both stations have a spring and autumn phytoplankton bloom; at station E1, the autumn bloom tends to dominate in terms of chlorophyll concentration. The last two decades have seen a warming of around 0.6°C per decade, and this is superimposed on several periods of warming and cooling over the past century. In general, over the Western English Channel domain, the end of the 20th century was around 0.5°C warmer than the first half of the century. The warming magnitude and trend is consistent with other stations across the north-west European Shelf and occurred during a period of reduced wind stress and increased levels of insolation (+20%); these are both correlated with the larger scale climatic forcing of the North Atlantic Oscillation.

Sediment investigations in the Kara Sea

AMS-14C dated sediment cores from the Ob and Yenisei estuaries and the adjacent inner Kara Sea were investigated to determine the siliclastic and organic carbon fluxes and their relationship to paleoenvironmental changes. The variability of sediment fluxes during Holocene times is related to the post-glacial sea-level rise and changes in river discharge and coastal erosion input. Whereas during the late/middle Holocene most of the terrigenous sediments were deposited in the estuaries and the areas directly off the estuaries, huge amounts of sediments accumulated on the Kara Sea shelf farther north during the early Holocene before about 9 Cal. kyrs. BP. The maximum accumulation at that time is related to the lowered sea level, increased coastal erosion, and increased river discharge due to the final stage of mountain deglaciation of the Putoran Massif. Increased supply of Yenisei-derived material indicated by peak magnetic susceptibility values probably occurred in climate-related pulses culminating near 11, 10, and 9 Cal. kyrs. BP. As sea level rose, the main Holocene depocenter migrated southward. Based on hydrogen index values and n-alkanes, the organic matter is predominantly of terrigenous origin. Maximum accumulation rates of 1.5 to more than 6 g/cm**2/y occurred in the early Holocene sediments, suggesting more humid climatic conditions with an increased vegetation cover in the source area at that time. In general, high organic carbon accumulation rates characterize the estuaries and the inner Kara Sea as important sink for terrigenous organic carbon. A high-resolution record of Holocene variability of magnetic susceptibility (MS) in an AMS14C-dated sediment core from the northern Yenisei estuary may indicate natural variability of Arctic climate change and river discharge on a centennial to millenial time scale. Short-term maxima in MS probably related to warmer climate, enhanced precipitation, intensified weathering/erosion and increased river discharge, display a frequency of about 300 to 700 years.