Geochemical data from pore water and solids from cores GS08-153-91GC12 and GS08-153-53-GC6, Arctic Mid-Ocean Ridge

Microbial communities and their associated metabolic activity in marine sediments have a profound impact on global biogeochemical cycles. Their composition and structure are attributed to geochemical and physical factors, but finding direct correlations has remained a challenge. Here we show a significant statistical relationship between variation in geochemical composition and prokaryotic community structure within deep-sea sediments. We obtained comprehensive geochemical data from two gravity cores near the hydrothermal vent field Loki's Castle at the Arctic Mid-Ocean Ridge, in the Norwegian-Greenland Sea. Geochemical properties in the rift valley sediments exhibited strong centimeter-scale stratigraphic variability. Microbial populations were profiled by pyrosequencing from 15 sediment horizons (59,364 16S rRNA gene tags), quantitatively assessed by qPCR, and phylogenetically analyzed. Although the same taxa were generally present in all samples, their relative abundances varied substantially among horizons and fluctuated between Bacteria- and Archaea-dominated communities. By independently summarizing covariance structures of the relative abundance data and geochemical data, using principal components analysis, we found a significant correlation between changes in geochemical composition and changes in community structure. Differences in organic carbon and mineralogy shaped the relative abundance of microbial taxa. We used correlations to build hypotheses about energy metabolisms, particularly of the Deep Sea Archaeal Group, specific Deltaproteobacteria, and sediment lineages of potentially anaerobic Marine Group I Archaea. We demonstrate that total prokaryotic community structure can be directly correlated to geochemistry within these sediments, thus enhancing our understanding of biogeochemical cycling and our ability to predict metabolisms of uncultured microbes in deep-sea sediments.

Analyses of Manganese nodules off Izu Island

Manganese nodules have been found by the author in the shallow waters of the Hyotan-se bank west of Shikime-jima, an island of the Izu archipelago in the Sea of Japan. The slopes around the bank are steep and rocks are exposed; gravels and coarse material cover the broad and flat plain on its top; andesite and basalt, which are very common in the bedrock, are found mingled with liparite gravels together with a number of manganese concretions from the bank.

Chemical composition of sediment core GeoB12309-5 from the northern Arabian Sea, its pore water profile and age depth relationship as well as CTD data obtained during cruise M74/3

The Arabian Sea off the Pakistan continental margin is characterized by one of the world's largest oxygen minimum zones (OMZ). The lithology and geochemistry of a 5.3 m long gravity core retrieved from the lower boundary of the modern OMZ (956 m water depth) were used to identify late Holocene changes in oceanographic conditions and the vertical extent of the OMZ. While the lower part of the core (535 - 465 cm, 5.04 - 4.45 cal kyr BP, Unit 3) is strongly bioturbated indicating oxic bottom water conditions, the upper part of the core (284 - 0 cm, 2.87 cal kyr BP to present, Unit 1) shows distinct and well-preserved lamination, suggesting anoxic bottom waters. The transitional interval from 465 to 284 cm (4.45 - 2.87 cal kyr BP, Unit 2) contains relicts of lamination which are in part intensely bioturbated. These fluctuations in bioturbation intensity suggest repetitive changes between anoxic and oxic/suboxic bottom-water conditions between 4.45 - 2.87 cal kyr BP. Barium excess (Baex) and total organic carbon (TOC) contents do not explain whether the increased TOC contents found in Unit 1 are the result of better preservation due to low BWO concentrations or if the decreased BWO concentration is a result of increased productivity. Changes in salinity and temperature of the outflowing water from the Red Sea during the Holocene influenced the water column stratification and probably affected the depth of the lower boundary of the OMZ in the northern Arabian Sea. Even if we cannot prove certain scenarios, we propose that the observed downward shift of the lower boundary of the OMZ was also impacted by a weakened Somali Current and a reduced transport of oxygen-rich Indian Central Water into the Arabian Sea, both as a response to decreased summer insolation and the continuous southward shift of the Intertropical Convergence Zone during the late Holocene.

Analysis of Manganese nodules from Sonne cruises SO06/1 and /2, "Hawaii-Tahiti-Transect", Teilprojekt ICIME

Manganese nodules research has focused on the area between the Clarion Fracture Zone to the North and the Clipperton Fracture Zone to the South where significant concentrations were found ni Ni-Cu. During the CCOP/SOPAC-IOC/IDOE International workshop on the "Geology Mineral Resources and Geophysics of the South Pacific" held in Fiji in September 1975, a working group on manganese nodules was formed by scientists from: CNEXO, Brest, the Institute of Oceanography, New Zealand, Imperial College, London and the Technical University of Aachen. A draft project was presented in July 1976 by J. Andrews, University of Hawaii and G. Pautot, Cnexo on a joint survey under the name of: "Hawaii-Tahiti Transect program". Further details were worked on in September 1976 during the International Geological Congress in Sydney with the participation of D. Cronan, Imperial College, Glasby, New Zealand Geological Survey and G. Friedrich, Aachen TU. The scientific final program was established in July 1977, planning on the participation of three research vessels: the Suroit (CNEXO), the Kana Keoki (U. of Hawaii) and the Sonne (Aachen TU). Several survey areas were selected across the Pacific Ocean (Areas A, B, C, D, E, F, G and H) with about the same crustal age (about 40 million years) and a similar water depths. Being near large fault zones, the ares would be adequate to study the influences of biological productivity, sedimentation rate and possibly volcanic activity on the formation and growth of manganese nodules. The influnece of volcanic activity study would particularly apply to area G being situated near the Marquesas Fracture Zone. The cruise from R/V Sonne started in August 1978 over areas C, D, F, G K. The R/V suroit conducted a similar expedition in 1979 over areas A, B, C, D, E, H and I. Others cruises were planned during the 1979-1980 for the R/V Kana Keoki. The present text relates the R/V Sonne Cruises SO-06/1 and SO-06/2 held within the frame work of this international cooperative project.

(Table 1, page 146) Iron, manganese and nickel contents of 21 ferromanganese nodules from Combe D'Izame and Mont Peyroux, Montagne Noire

Ferromanganese nodules (equivalent to Recent manganese nodules) are described from the Upper Devonian griotte (red pelagic limestone) of the Montagne Noire (S. France) and the Cephalopodenkalk of the Rheinisches Schiefergebirge, West Germany. They occur as encrustations, commonly exhibiting colloform structures, around skeletal material and limestone clasts. The nodules are associated with encrusting foraminifera and a development in the sublittoral environment is envisaged. Chemically, the ferromanganese nodules are depleted in manganese relative to iron, compared with Recent nodules, a loss which is attributed to diagenetic migration of manganese. Electron probe studies show that manganese covaries positively with calcium, but negatively with iron and silicon. Diagenetic enrichment of hematite occurs in the griotte at hardground horizons where two periods of mineralization can be established. The Devonian ferromanganese nodules show that solution of nodules has not occurred on burial.

Composition of bottom sediments, rocks, and ores from the Tropical Atlantic

Geological features of some areas of the Tropical Atlantic (stratigraphy, tectonic structure, lithology, distribution of ore components in bottom sediments, petrography of bedrocks, etc.) are under consideration in the book. Regularities of concentration of trace elements in iron-manganese nodules, features of these nodules in bottom sediments, distribution of phosphorite nodules and other phosphorites have been studied. Much attention is paid to rocks of the ocean crust. A wide range of mineralization represented by magnetite, chromite, chalcopyrite, pyrite, pentlandite, and other minerals has been found.

Sulphur isotope composition in the Gulf of California and the Eastern Pacific

The book is devoted to study of diagenetic changes of organic matter and mineral part of sediments and interstitial waters of the Pacific Ocean due to physical-chemical and microbiological processes. Microbiological studies deal with different groups of bacteria. Regularities of quantitative distribution and the role of microorganisms in geochemical processes are under consideration. Geochemical studies highlight redox processes of the early stages of sediment diagenesis, alterations of interstitial waters, regularities of variations in chemical composition of iron-manganese nodules.

(Appendix A) Dissolved manganese concentrations during POLARSTERN Cruise ARK-XXII/2

A total of 773 samples were analysed for dissolved manganese (Mn) in the Arctic Ocean aboard R.V. Polarstern during expedition ARK XXII/2 from 28 July until 07 October 2007 from Tromsø (Norway) to Bremerhaven. Concentrations of Mn were elevated in the surface layer with concentrations of up to 6 nM over the deep Basins and over 20 nM in the Laptev Sea. The general distribution of Mn through the water column is consistent with previous studies, but there are differences in the absolute concentrations that are most likely related to differences in sample area, sampling and filtration. The elevated concentrations of Mn in the surface layer are related to fresh water input. This was visible in the strong negative correlations observed between dissolved Mn and salinity. The correlation between Mn and salinity and the correlation between Mn and the quasi conservative trace water mass tracer PO4*, showed fluvial and melt water input and the Pacific and Atlantic origin of the surface waters. A large portion of the Mn delivered by the Arctic rivers is removed in the shelf seas and does not pass into the central basins. Most likely a benthic flux is at the origin of the elevated concentrations of Mn near the sediments in the Barents and Kara Seas. These elevated concentrations of Mn apparently affected the deep basins as well, as maxima in the concentrations of Mn were observed that corresponded with lowered transmission over the continental slope. A maximum in the concentration of Mn in the deep basin corresponded with anomalies in light transmission, potential temperature and dissolved iron, confirming the hydrothermal origin. The hydrothermal plume was observed throughout the Nansen Basin and over the deep Gakkel Ridge around 2500 m depth and a smaller plume was observed around 3200 m. The concentration of Mn at the Mn maximum around 2500 m depth decreased exponentially, consistent with a first order scavenging model. The concentrations of Mn were extremely low in the deep Makarov Basin (~0.05 nM) and slightly higher in the Eurasian Basin (~0.1 nM) outside the influence of the hydrothermal activity.

Geochemistry of hydrothermal solutions, ores, and biota from hydrothermal fields at the East Pacific Rise axis near 9°50'N

Hydrothermal solutions were examined in a circulation system that started to develop after the 1991 volcanic eruption in the axial segment of the EPR between 9°45'N and 9°52'N. Within twelve years after this eruption, diffusion outflow of hot fluid from fractures in basaltic lavas gave way to focused seeps of hot solutions through channels of hydrothermal sulfide edifices. An example of the field Q demonstrates that from 1991 to 2003 H2S concentrations decreased from 86 to 1 mM/kg, and the Fe/H2S ratio simultaneously increased by factor 1.7. This fact can explain disappearance of microbial mats that were widespread within the fields before 1991. S isotopic composition of H2S does not depend on H2S concentration. This fact testifies rapid evolution of the hydrothermal system in the early years of its evolution. Carbon in CH4 from hot fluid sampled in 2003 is richer in 12C isotope than carbon in fluid from the hydrothermal field at 21°N EPR. It suggests that methane comes to the Q field from more than one source. Composition of particulate matter in hydrothermal solutions indicates that it was contributed by biological material. Experimental solutions with labeled substrates (t<70°C) show evidence of active processes of methane oxidation and sulfate reduction. Our results indicate that, during 12-year evolution of the hydrothermal system, composition of its solutions evolved and approached compositions of solutions in mature hydrothermal systems of the EPR.

Composition of interstitial waters from sediments of the Gulf of California

The book is devoted to study of diagenetic changes of organic matter and mineral part of sediments and interstitial waters of the Pacific Ocean due to physical-chemical and microbiological processes. Microbiological studies deal with different groups of bacteria. Regularities of quantitative distribution and the role of microorganisms in geochemical processes are under consideration. Geochemical studies highlight redox processes of the early stages of sediment diagenesis, alterations of interstitial waters, regularities of variations in chemical composition of iron-manganese nodules.

Description and iron and manganese content of ferromanganese nodules from Oneida Lake, NY

Ferromanganese nodules in the deep-sea and in freshwater lakes usually accrete layers rich in manganese oxides alternating with layers rich in iron oxides. The mechanism producing these alternating layers is unknown; indeed, the mechanism producing the nodules themselves is unknown. In Oneida Lake, New York, precipitants from the lake water and the surfaces of nodules at the sediment-water interface are enriched in Mn, whereas nodules buried in lake sediments have surface layers enriched in Fe. It is hypothesized here, using field and laboratory evidence, that reduction and mobilization of Mn from the nodule surface during periods of anoxic sediment cover produce the high Fe layers observed in the nodules.

Geological, geochemical and biogeochemical data on boundary zones of the Atlantic Ocean

Results of studies in two biogeochemically active zones of the Atlantic Ocean (the Benguela upwelling waters and the region influenced by the Congo River run-off) are reported in the book. A multidisciplinary approach included studies of the major elements of the ocean ecosystem: sea water, plankton, suspended matter, bottom sediments, interstitial waters, aerosols, as well as a wide complex of oceanographic studies carried out under a common program. Such an approach, as well as a use of new methodical solutions led to obtaining principally new information on different aspects of oceanology.

Geochemistry of sediment cores GeoB13820-1 and GeoB13863-1 from the western South Atlantic

Here, we present results from sediments collected in the Argentine Basin, a non-steady state depositional marine system characterized by abundant oxidized iron within methane-rich layers due to sediment reworking followed by rapid deposition. Our comprehensive inorganic data set shows that iron reduction in these sulfate and sulfide-depleted sediments is best explained by a microbially mediated process-implicating anaerobic oxidation of methane coupled to iron reduction (Fe-AOM) as the most likely major mechanism. Although important in many modern marine environments, iron-driven AOM may not consume similar amounts of methane compared with sulfate-dependent AOM. Nevertheless, it may have broad impact on the deep biosphere and dominate both iron and methane cycling in sulfate-lean marine settings. Fe-AOM might have been particularly relevant in the Archean ocean, >2.5 billion years ago, known for its production and accumulation of iron oxides (in iron formations) in a biosphere likely replete with methane but low in sulfate. Methane at that time was a critical greenhouse gas capable of sustaining a habitable climate under relatively low solar luminosity, and relationships to iron cycling may have impacted if not dominated methane loss from the biosphere.