Alkenone UK37 measured in the upper water column at pump stations CariacoTrench, Peru and Vertex

A series of long-chain (C37, C38, C39), primarily di and tri-unsaturated methyl and ethyl ketones, first identified in sediments from Walvis Ridge off West Africa and from Black Sea (de Leeuw et al., 1979), has been found in marine sediments throughout the world (Brassell et al., 1986 doi:10.1038/320129a0). The marine coccolithophorid Emiliania huxleyi and members of the class Prymnesiophyceae are now the recognized sources of these compounds (Volkman et al., 1979; Marlowe, et al., 1984). Experiments with laboratory cultures of algae showed the degree of unsaturation in the ketone seris biosynthesized depends on growth temperature (Brassell et al., 1986; Marlowe, 1984), a physiological respons observed for classical membrane lipids (vanDeenen et al., 1972). Brassell and co-workers (Brassell et al., 198; Brassell et al., 1986b) thus proposed that systematic fluctuations in the unsaturation of these alkenones noted down-core in sediments from the Kane Gap region of the north-east tropical Atlantic Ocean and correlated with glacial-interglacial cycles provide an organic geochemical measure of past sea-surface water temperatures. Using laboratory cultures of E. huxleyi, we have calibrated changes in the unsaturation pattern of the long-chain ketone series versus growth temperature. The calibration curve is linear and accurtely predicts unsuturation patterns observed in natural particulate materials collected from oceanic waters of known temperature. We present evidence supporting the proposed paleotemperature hypothesis (Brassell et al., 1986, Brassel et al., 1986b) and suggesting absolute 'sea-surface temperatures' for a given oceanic location can be estimated from an analysis of long-chain ketone compositions preserved in glacial and interglacial horizons of deep-sea sediment cores.

Concentration of particulate matter and its dispersion factor in surface waters of the Canary upweling region, East Atlantic

Particulate matter concentration and water temperature at 5 m depth level are compared in the Canary upwelling region to the east of the Cape Blanc. It was found that accumulation of particulate matter was timed to hydrofrontal zones. Particle size distributions for particulate matter obtained using the Coulter counter agree with the hyperbolic law (of the Junge type) with double values for the size parameter, which changes for particle diameters of 5-6 microns. Average values for the size parameter in the region of the upwelling are significantly lower than in the open ocean. Specific surface of particulate matter associated with reactivity differs significantly on different sides of the upwelling front and increases beyond the upwelling.

(Table 2) Particulate organic carbon concentrations in the water column of the Barents Sea in August-September 1997

A comparative estimation of particulate organic matter concentration in seawater in various regions of the Barents Sea was carried out on the basis of materials collected by authors in August-September 1997. It is shown that the major feature of near-bottom distribution of particulate organic matter is distinct decrease in its concentration from off-shore areas of the Murman and Novaya Zemlya coasts and the Franz Josef Land Archipelago toward the central part of the Barents Sea. Using a method of mean and maximum concentrations of particulate organic matter, an attempt was made to estimate its fluxes from the surface to the bottom.

Isotopic ratios and concentrations for mineral-associated and particulate organic fractions of sediment core Wilson_Lake samples

The flux of sediment and organic carbon from continents to the coastal ocean is an important factor governing organic burial in coastal sediments, and these systems preserve important records of environmental and biogeochemical conditions during past global change events. Burial of organic materials in coastal systems can be promoted by chemical resilience or through protection by association with mineral surfaces, but the role and influence of these processes on organic records from ancient sediments is poorly known. We studied sediment and organic matter burial as particulate organic matter (POM) and mineral-bound organic matter (MOM) in near-shore marine sediments from the Wilson Lake core (New Jersey, USA) that span the Paleocene-Eocene thermal maximum (PETM), a climatic perturbation 55.9 Myr ago. Our results show that distinct POM and MOM fractions can be isolated from sediments. Both fractions appear to be dominated by terrestrial material, but POM consisted primarily of recently synthesized material whereas MOM included a significant fraction of pre-aged organic matter from soils or ancient sediments. Variation in organic burial through the PETM is associated with changes in inorganic nitrogen burial, clay mineralogy, and clastic grain size that we associate with enhanced continental weathering, erosion and redeposition of ancient kaolinites, and eustatic sea level variation, respectively. These results provide a new perspective on factors governing carbon burial and carbon isotope records in ancient marine margin settings and offer information on rate and phasing of late Paleocene/early Eocene Earth system changes that may constrain interpretations of the cause of the PETM climate change event.