(Table 1) Attenuation coefficient of lateral propagating light in sea ice, southern Beaufort Sea

The attenuation property of a lateral propagating light (LPL) in sea ice was measured using an artificial lamp in the Canadian Arctic during the 2007/2008 winter. A measurement method is proposed and applied whereby a recording instrument is buried in the sea ice and an artificial lamp is moved across the instrument. The apparent attenuation coefficient µ(lamda) for the lateral propagating light is obtained from the measured logarithmic relative variation rate. With the exception of blue and red lights, the attenuation coefficient changed little with wavelength, but changed considerably with depth. The vertical decrease of the attenuation coefficient was found to be correlated with salinity: the greater the salinity, the greater the attenuation coefficient. A clear linear relation of salinity and the lateral attenuation coefficient with R2 = 0.939 exists to address the close correlation of the attenuation of LPL with the scattering from the brine. The observed attenuation coefficient of LPL is much larger than that of the vertical propagation light, which we speculate to be caused by scattering. Part of this scattered component is transmitted out of the sea ice from the upper and lower surfaces.

(Table 2) Similarity Indexes (Pearson's correlation coefficient) of the silicoflagellate assemblages of IODP Exp302

The silicoflagellate and ebridian assemblages in early middle Eocene Arctic cores obtained by IODP Expedition 302 (ACEX) were studied in order to decipher the paleoceanography of the upper water column. The assemblages in Lithologic Unit 2 (49.7-45.1 Ma), one of the biosiliceous intervals, were usually endemic as compared to the assemblages that occurred outside of the Arctic Ocean. The presence of these endemic assemblages is probably due to a unique environmental setting, controlled by the degree of mixing between the low-salinity Arctic waters and relatively high salinity waters supplied from outside the Arctic Ocean, such as the Atlantic and possibly the Western Siberian Sea. Using the basin-to-basin fractionation model, the early middle Eocene Arctic Ocean corresponds to an estuarine circulation type, which includes the modern-day Black Sea. The abundant down-core occurrence of ebridians strongly suggests the past presence of low-salinity waters, and may indicate that low oxygen concentrations prevailed in the euphotic layer, on the basis of the ecology of the modern ebridian Hermesinum adriaticum.

Phosphorus partition and acumulation rates in sediments of ODP Legs 130 and 138

Understanding phosphorus (P) geochemistry and burial in oceanic sediments is important because of the role of P for modulating oceanic productivity on long timescales. We investigated P geochemistry in seven equatorial Pacific sites over the last 53 Ma, using a sequential extraction technique to elucidate sedimentary P composition and P diagenesis within the sediments. The dominant P-bearing component in these sediments is authigenic P (61-86% of total P), followed in order of relative dominance by iron-bound P (7-17%), organic P (3-12%), adsorbed P (2-9%), and detrital P (0-1%). Clear temporal trends in P component composition exist. Organic P decreases rapidly in younger sediments in the eastern Pacific (the only sites with high sample resolution in the younger intervals), from a mean concentration of 2.3 µmol P/g sediment in the 0-1 Ma interval to 0.4 µmol/g in the 5- 6 Ma interval. Over this same time interval, decreases are also observed for iron-bound P (from 2.1 to 1.1 µmol P/g) and adsorbed P (from 1.5 to 0.7 µmol P/g). These decreases are in contrast to increases in authigenic P (from 6.0-9.6 µmol P/g) and no significant changes in detrital P (0.1 µmol P/g) and total P (12 µmol P/g). These temporal trends in P geochemistry suggest that (1) organic matter, the principal shuttle of P to the seafloor, is regenerated in sediments and releases associated P to interstitial waters, (2) P associated with iron-rich oxyhydroxides is released to interstitial waters upon microbial iron reduction, (3) the decrease in adsorbed P with age and depth probably indicates a similar decrease in interstitial water P concentrations, and (4) carbonate fluorapatite (CFA), or another authigenic P-bearing phase, precipitates due to the release of P from organic matter and iron oxyhydroxides and becomes an increasingly significant P sink with age and depth. The reorganization of P between various sedimentary pools, and its eventual incorporation in CFA, has been recognized in a variety of continental margin environments, but this is the first time these processes have been revealed in deep-sea sediments. Phosphorus accumulation rate data from this study and others indicates that the global pre-anthropogenic input rate of P to the ocean (20x10**10 mol P/yr) is about a factor of four times higher than previously thought, supporting recent suggestions that the residence time of P in the oceans may be as short as 10000-20000 years.