(Table 1) Oxygen isotope composition and comparison between ages and sea surface temperature from sediment core KH-79-3_L-3

The Japan Sea experienced bottom water anoxia at the last glacial maximum (LGM) since it is surrounded by four shallow straits, the sill depths of which are close to, or shallower than, the drop in sea level (~120 m) that occurred then. A distinctive negative d18O excursion of planktonic foraminifera also took place during the LGM. This excursion has been interpreted from foraminiferal data as recording a drop in the paleosalinity of surface waters on the assumption of a constant low sea surface temperatures between 34 and 11 ka. We present here a profile of alkenone-based sea surface temperatures (alkenone-SSTs) over the past 36 kyr. Our results suggest that SSTs during the LGM were much higher than those previously assumed. After considering the factors that might affect estimation of alkenone-SSTs and comparisons of core-top alkenone-SSTs values with values for modern seawater we conclude that the higher alkenone-SSTs during the LGM are reliable and reasonable. These warm SSTs were probably caused by radiative equilibrium associated with the development of stable water stratification in the Japan Sea during the LGM.

Sea surface temperature and age analysis from sediment core KT94-15_PC-9, XP98-PC-4 and XP98-PC-2

The Japan Sea experienced bottom water anoxia at the last glacial maximum (LGM) since it is surrounded by four shallow straits, the sill depths of which are close to, or shallower than, the drop in sea level (~120 m) that occurred then. A distinctive negative d18O excursion of planktonic foraminifera also took place during the LGM. This excursion has been interpreted from foraminiferal data as recording a drop in the paleosalinity of surface waters on the assumption of a constant low sea surface temperatures between 34 and 11 ka. We present here a profile of alkenone-based sea surface temperatures (alkenone-SSTs) over the past 36 kyr. Our results suggest that SSTs during the LGM were much higher than those previously assumed. After considering the factors that might affect estimation of alkenone-SSTs and comparisons of core-top alkenone-SSTs values with values for modern seawater we conclude that the higher alkenone-SSTs during the LGM are reliable and reasonable. These warm SSTs were probably caused by radiative equilibrium associated with the development of stable water stratification in the Japan Sea during the LGM.

Chemical observations in the Red Sea and the inner Gulf of Aden during the International Indian Ocean Expedition 1964/65

The Red Sea has a special place among the adjacent seas of the world. High evaporation, exclusion of its deep water from contact with the Indian Ocean proper and complete absence of continental drainage may result special conditions of the chemistry of the Red Sea. This paper aims to describe and explain the peculiarity of the hydrochemical situation. The influence of the topography, of the inflow and outflow through the straights of Bab el Mandeb, of the evaporation, of the stability of the water layers, and of the circulation will be studied. An attempt is made to estimate the apparent oxygen ultilisation in order to obtain an indication of the biological activity. A further attempt is made toward the quantitative estimation of the circulation of the nutrients and also to obtain some information about transport, dissolution, and precipitation of calcium carbonate. The basis of these investigations are mainly observations of R. V. "Meteor" during the International Indian Ocean Expedition 1964/65. The determination of dissolved oxygen, dissolved inorganic phosphate, nitrate, nitrite, ammonia, pH, alkalinity, silicate as well as salinity and temperature forms the necessary basis for such an investigation of the chemical conditions. In the first chapter the methods and some modifications for the determination of the chemical properties as applied during the I.I.O.E. cruise of R. V. "Meteor" are described. The new methods, as worked out and tested under sea going conditions during several years by the author, are described in more detail. These are the methods for nitrate, silicate, the automatic determination of dissolved inorganic phosphate and silicate, the automated determination of total phosphorus, the in situ recording of the oxygen tension, and the modification for the determination of ammonia, calcium, and dissolved oxygen. With these revised methods more than 18,000 determinations have been carried out during the Indian Ocean cruise. The complete working up of the chemical data of the Indian Ocean Expedition of R. V. "Meteor" is devided into four sections: Contributions 1) to the Chemistry of the Red Sea and the Inner Gulf of Aden, 2) to the Gulf of Aden and the Somali Coast Region, 3) to the Western Indian Coast Region, and 4) to the Persian Gulf and the Straits of Oman. This paper presents the first contribution. The special hydrographical conditions are discussed. It can be shown, that the increase of salinity in the surface waters from the south to the north of the Red Sea is only to about 30 % due to evaporation. The remaining increase is presumed to be due to the admixture of deep water to the surface layers. A special rate for the consumption of oxygen (0.114 ml/ l/a) is derived for the deep water of the Red Sea at 1500 m. Based upon the distribution of the dissolved oxygen along the axii of the Red Sea, a chematic model for the longitudinal circulation of the Red Sea is constructed. This model should be considered as a first approximation and may explain the special distribution of phosphate, nitrate, and silicate. Based upon the evaluation of the residence time of the deep water a dissolution rate for silicate is estimated as 1 mygat/a. It seems possible to calculate residence times of water masses outside the Red Sea from the silicate content. The increase of silicate and the consumption of oxygen lead to residence times of the water below the thermocine of 30 to 48 years. The distribution of oxygen in the Straits of Bab el Mandeb is described and discussed. The rate of consumption of the oxygen in the outflowing Red Sea water is estimated to 8.5 ml/ l/a. This rather high rate is explained with reference to the special conditions in the outflowing water. The Red Sea water is characterized initially by a relative high content of oxygen and a low content of nutrients. The increase in nutrients and the decrease in the oxygen content is a secondary process of the Red Sea water on its way to the Arabian Sea. Based upon the vertical distribution of the dissolved inorganic phosphate vertical exchange coefficients of 1 - 4 g/cm/sec and vertical current speeds of 10**-5 to 10**-4 cm/sec are calculated for some stations in the Red Sea. The distribution of phosphate, silicate, nitrate, nitrite and ammonia for the Red Sea and the Straits of Bab el Mandeb are discussed. The special circulation is evaluated and the balance of the nutrients is estimated by means of the brutto transport. The nutrient deficit is assumed to be balanced by sporadic inflow of intermediate water from the Gulf of Aden. An example for such an inflow has been observed and is demonstrated. The silicate-salinity relationships are a suitable way for characterizing water masses in the Red Sea. Equations for the calculation of the different components from the carbonate system, the ion activities, and the calcium carbonate saturation are evaluated. The influence of temperature and pressure is taken into account. The carbonate saturation is calculated from the determined concentrations of calcium, alkalinity, and the hydrogen ion activity. Saturation values of 320 % are found for the surface layer and of 100% ± 1 for the deep water. The extraordinary equilibrium conditions may explain the constant Ca/Cl ratio and also the sedimentation of undissolved carbonate skelecons even in greater depths. A main sedimentation rate of 2 * 10**-3cm/year is evaluated from a total sedimentation of 10 * 106 to/a of calcium carbonate in the Red Sea. The appendix contains those data, which are not published in the data volume of the I.I.O.E. expedition of R. V. "Meteor".

Radium in Arctic surface water

The transpolar drift is strongly enriched in 228Ra accumulated on the wide Arctic shelves with subsequent rapid offshore transport. We present new data of Polarstern expeditions to the central Arctic and to the Kara and Laptev seas. Because 226Ra activities in Pacific waters are 30% higher than in Atlantic waters, we correct 226Ra for the Pacific admixture when normalizing 228Ra with 226Ra. The use of 228Ra decay as age marker critically depends on the constancy in space and time of the source activity, a condition that has not yet adequately been tested. While 228Ra decays during transit over the central basin, ingrowth of 228Th could provide an alternative age marker. The high 228Th/228Ra activity ratio (AR = 0.8-1.0) in the central basins is incompatible with a mixing model based on horizontal eddy diffusion. An advective model predicts that 228Th grows to an equilibrium AR, the value of which depends on the scavenging regime. The low AR over the Lomonosov Ridge (AR = 0.5) can be due to either rapid transport (minimum age without scavenging 1.1 year) or enhanced scavenging. Suspended particulate matter load (derived from beam transmission and particulate 234Th) and total 234Th depletion data show that scavenging, although extremely low in the central Arctic, is enhanced over the Lomonosov Ridge, making an age of 3 years more likely. The combined data of 228Ra decay and 228Th ingrowth confirm the existence of a recirculating gyre in the surface water of the eastern Eurasian Basin with a river water residence time of at least 3 years.

Surface characteristics and metazoa occurrence at ice station PS67/006-1 during POLARSTERN cruise ANT-XXII/2 (Nov 2004-Jan 2005)

The surface and sub-ice layer habitats and their metazoan fauna were studied on a drifting pack-ice floe in the western Weddell Sea from 29 November 2004 to 1 January 2005 during the "Ice Station POLarstern" (ISPOL). Flooding of the floe occurred at some places, and the establishment of surface layers with a brownish colour due to growing algae was observed at several sampling sites. The average surface-layer temperature, brine salinity and brine volume were -1.4 °C, 25.3 and 54%, respectively. The temperature-salinity relationship in the surface layer was seldom at equilibrium conditions. Chlorophyll a (Chl a) concentrations in the brine varied between 1.0 and 53.5 µg /L. Surface-layer thickness, salinity, Chl a concentration and copepod abundances were generally higher at the edge of the floe than in the inner part. The sympagic copepod species Drescheriella glacialis/racovitzai and Stephos longipes, with abundances ranging between 0 and 3830 ind/L (median: 2 ind/L) and 0 and 1293 ind/L (median: 4 ind/L), respectively, were the dominant members of the surface-layer meiofauna. Their populations consisted mainly of adults and early naupliar stages, which points to an active reproduction of these species within the surface layer. Other taxa found in the surface layer were undetermined turbellarians, the gastropod Tergipes antarcticus, and, for the first time, the ctenophore Callianira antarctica, and the amphipods Eusirus antarcticus and Eusirus tridentatus. During the course of our study, slight melting at the ice underside took place, releasing sympagic organisms to the water column. Chl a concentrations in the sub-ice water layer were very low (0.1-0.5 µg /L), except for 25 December when the Chl a concentration at 0 m depth increased to 2.3 µg /L. The most dominant sympagic copepod species found in the sub-ice layer was Ectinosoma sp., with abundances ranging between 1 and 599 ind/m**3 (median: 25 ind/m**3). Other sympagic copepod species occurring regularly in this habitat were D. glacialis/racovitzai, Diarthrodes cf. lilacinus, Idomene antarctica and S. longipes. All of these sympagic species were generally found in higher abundances at 0 m depth underneath the ice than at 5 m depth, in contrast to pelagic copepod species that occurred more frequently at 5 m depth. Niche separation and probable life-cycle strategies of dominant sympagic metazoans are discussed.