(Table 3) Barium barite and excess comparison, accumulation rates and productivity from surface sediments

Since Dymond et al. (1992, doi:10.1029/92PA00181) proposed the paleoproductivity algorithm based on "Bio-Ba", which relies on a strong correlation between Ba and organic carbon fluxes in sediment traps, this proxy has been applied in many paleoproductivity studies. Barite, the main carrier of particulate barium in the water column and the phase associated with carbon export, has also been suggested as a reliable paleoproductivity proxy in some locations. We demonstrate that Ba(excess) (total barium minus the fraction associated with terrigenous material) frequently overestimates Ba(barite) (barium associated with the mineral barite), most likely due to the inclusion of barium from phases other than barite and terrigenous silicates (e.g., carbonate, organic matter, opal, Fe-Mn oxides, and hydroxides). A comparison between overlying oceanic carbon export and carbon export derived from Ba(excess) shows that the Dymond et al. (1992) algorithm frequently underestimates carbon export but is still a useful carbon export indicator if all caveats are considered before the algorithm is applied. Ba(barite) accumulation rates from a wide range of core top sediments from different oceanic settings are highly correlated to surface ocean 14C and Chlorophyll a measurements of primary production. This relationship varies by ocean basin, but with the application of the appropriate f ratio to 14C and Chlorophyll a primary production estimates, the plot of Ba(barite) accumulation and carbon export for the equatorial Pacific, Atlantic, and Southern Ocean converges to a global relationship that can be used to reconstruct paleo carbon export.

Sediment rates and structures in Bay of Kiel, Baltic Sea

Density and diversity of bottom fauna population as dependent on sediment types and water depth is largely well known in Kiel Bay. This is in contrast to structures and processes of bioturbation, although generally it has a big influence on the benthic boundary layer and its processes, e.g., the metabolism of the bottom fauna, the mechanical properties, the age dating, and the large field of chemical processes. In the densely inhabited sands and muddy sands of the shallower waters with sediment thicknesses of some decimeters only, bioturbation is usually ubiquitous, and most of the structures left are monotonously of "biodeformational" character. At greater water depths, however, where a sedimentary column of several meters of Holocene is developed, the X-ray radiographs of numerous sediment cores show heterogeneous biogenic structures with regional and stratigraphical differentiation. They are described in terms of ichnofabrics and are interpreted on ethological knowledge of the related macrobenthos species. lmportant organisms creating specific traces include the bivalve Arctica (Cyprina) islandica and the polychaete worm Pectinaria koreni. These species are abundant in Kiel Bay and produce by their crawling-plowing mode of locomotion, a characteristic biogenic stratification, the "plow-sole structure". Other typical biogenic structures are tube traces, which are left by a number of different polychaetes occurring either singly, or as U-pairs mainly in mud sediments. Although sea urchins are rare to absent in Kiel Bay, layers of their characteristic traces Scolicia occur as witness of paleohydrographic events in channel sediments of the central bay. Plow-sole traces, polychaete-tube ichnofabric, Scolicia layers and alternations of laminated and bioturbated layers are considered as building blocks of a future "ichnostratigraphy" of Kiel Bay.

Degradation rates and productivity signals of organic-walled dinoflagellate cyst species in surface sediment samples

To understand the role of the ocean within the global carbon cycle, detailed information is required on key-processes within the marine carbon cycle; bio-production in the upper ocean, export of the produced material to the deep ocean and the storage of carbon in oceanic sediments. Quantification of these processes requires the separation of signals of net primary production and the rate of organic matter decay as reflected in fossil sediments. This study examines the large differences in degradation rates of organic-walled dinoflagellate cyst species to separate these degradation and productivity signals. For this, accumulation rates of cyst species known to be resistant (R-cysts) or sensitive (S-cysts) to aerobic degradation of 62 sites are compared to mean annual chlorophyll-a, sea-surface temperature, sea-surface salinity, nitrate and phosphate concentrations of the upper waters and deep-water oxygen concentrations. Furthermore, the degradation of sensitive cysts, as expressed by the degradation constant k and reaction time t, has been related to bottom water [O2]. The studied sediments were taken from the Arabian Sea, north-western African Margin (North Atlantic), western-equatorial Atlantic Ocean/Caraibic, south-western African margin (South Atlantic) and Southern Ocean (Atlantic sector). Significant relationships are observed between (a) accumulation rates of R-cysts and upper water chlorophyll-a concentrations, (b) accumulation rates of S-cysts and bottom water [O2] and (c) degradation rates of S-cysts (kt) and bottom water [O2]. Relationships that are extremely weak or are clearly insignificant on all confidence intervals are between (1) S-cyst accumulation rates and chlorophyll-a concentrations, sea-surface temperature (SST), sea-surface salinity (SSS), phosphate concentrations (P) and nitrate concentrations (N), (2) between R-cyst accumulation rates and bottom water [O2], SST, SSS, P and N, and between (3) kt and water depth. Co-variance is present between the parameters N and P, N, P and chlorophyll-a, oxygen and water depth. Correcting for this co-variance does not influence the significance of the relationship given above. The possible applicability of dinoflagellate cyst degradation to estimate past net primary production and deep ocean ventilation is discussed.

(Table 1) Radiolarian accumulation rates and geochemistry of ODP Site 184-1143

Late Miocene-Recent micropaleontological and geochemical records from Ocean Drilling Program (ODP) Site 1143 in the southern South China Sea (SCS) indicate that increase and decrease in abundance of siliceous plankton may be controlled mainly by the input of nutrients derived from land and provided by upwelling. A high export production event - a "biogenic bloom" event - occurred in the southern SCS between 12 and 6 Ma. During this period, high ratios of smectite/(illite + chlorite), smectite/quartz and Al/K indicate a high weathering intensity of the Asian continent, possibly due to the intensification of the East Asian Summer Monsoon (EASM), which may have increased the net flux of nutrients to the ocean, both directly through terrestrial input and indirectly through upwelling activity. A drop in Ba/Ti, Al/Ti and Ca/Ti values around 6 Ma may indicate a lowering of productivity, possibly due to the large consumption of sea surface nutrients by the "biogenic bloom". Alternatively, it may indicate a shift in terrigenous input source area. At about 5.4 Ma, a decrease in weathering intensity, as indicated by a sudden decrease in the values of smectite/(illite + chlorite), smectite/quartz and Al/K, might have led to a sudden decrease of terrestrial nutrient input to the SCS. We suggest that the biogenic bloom ended when nutrients in surface waters were exhausted, because of a decrease in supply as well as a decrease in upwelling intensity due to weakening of the EASM. As a result, radiolarians were absent in the studied area between ~6 and 3.2 Ma. At ~3.2 Ma, radiolarians began to recover, possibly because the start of Northern Hemispheric glaciation and the rapid uplift of the Tibet Plateau led to intensification of the East Asian monsoon. After the Mid-Pleistocene Climate Transition at 0.9 Ma, the abundance and mass accumulation rates of radiolarians increased, probably as a result of increased upwelling activity driven by the increasing intensity of the summer monsoon.

(Table 1) Methane concentrations, MOX rates and MOB abundance in arctic aquatic ecosystems of the Lena Delta, Northeast Siberia

Large amounts of organic carbon are stored in Arctic permafrost environments, and microbial activity can potentially mineralize this carbon into methane, a potent greenhouse gas. In this study, we assessed the methane budget, the bacterial methane oxidation (MOX) and the underlying environmental controls of arctic lake systems, which represent substantial sources of methane. Five lake systems located on Samoylov Island (Lena Delta, Siberia) and the connected river sites were analyzed using radiotracers to estimate the MOX rates, and molecular biology methods to characterize the abundance and the community composition of methane-oxidizing bacteria (MOB). In contrast to the river, the lake systems had high variation in the methane concentrations, the abundance and composition of the MOB communities, and consequently, the MOX rates. The highest methane concentrations and the highest MOX rates were detected in the lake outlets and in a lake complex in a floodplain area. Though, in all aquatic systems we detected both, Type I and II MOB, in lake systems we observed a higher diversity including MOB, typical of the soil environments. The inoculation of soil MOB into the aquatic systems, resulting from permafrost thawing, might be an additional factor controlling the MOB community composition and potentially methanotrophic capacity.

Growth rates and possible age of a North Pacific manganese nodule

The rate of accumulation of a ferromanganese coating on a fragment of pillow basalt was estimated using a variety of techniques. Unsupported 230 Th activity decrease in the oxide layer, K/A dating of the basalt, fission tracks dating of the glassy layer around the basalt, thickness of the palagonitization rind, and integrated 230 Th activity give ages from approximately 3 x 10-6 years to 5 x 10-3 years. Data suggest that the ferromanganese material formed rapidly (33 mm/10-6 years) and by hydrothermal or volcanic processes.