Biochemical, geochemical and sedimentological study of ODP Leg 112 samples

Organic-rich diatomaceous muds from Ocean Drilling Program Leg 112 (offshore Peru) are the subject of a comprehensive organic diagenetic study covering the burial interval, <1 to >100 m. The organic matter has been classified in terms of its elemental, biochemical, and geochemical compositions. About 60% of the organic carbon in sediments from <1 m can be attributed to hydrolyzable, biochemical constituents, while at 22 m this figure decreased to 20%. Pyrolysis-gas chromatography and gas chromatography-mass spectrometry chromatograms of these same sediments contain mainly hydrocarbons and nitrogenous compounds, with low amounts of other heteroatomic compounds, even though the total organic matter is rich in oxygen (about 35 atoms per 100 carbon atoms) and sulfur (1 to 5 atoms per 100 C atoms). Overall, the organic matter in these sediments, even at these shallow depths and young ages, has many of the geochemical features of far more deeply buried sediments, providing further strong evidence for the claim that "kerogen-formation" is a very early diagenetic process.

Abundance of zooplankton based on a long-term study at the Galata transect and covers the spring-summer periods from 1967 till 2005

The dataset is based on a long-term study (38 years) at the Galata transect and covers the spring-summer periods from 1967 till 2005. The whole dataset is composed of 360 data of total zooplankton biomass and abundance . Samples were collected in discrete layers 0-10m, 10-20m, 10-25m, 25-50m, 50-70m, 50-100m, 100-150. Mesozooplankton abundance: the collected material was analysed using the method of Domov (1959). Samples were brought to volume of 25-30 ml depending upon zooplankton density and mixed intensively until all organisms were distributed randomly in the sample volume. After that 5 ml of sample was taken and poured in the counting chamber for taxomomic identification and count. Large (> 1 mm body length) and not abundant species were calculated in whole sample. Counting and measuring of organisms were made in the Dimov chamber under the stereomicroscope to the lowest taxon possible. Taxonomic identification was done at the Institute of Fishery Resource by Prof. Asen Konsulov and Institute of Oceanology by Prof. Asen Konsulov, Lyudmila Kamburska and Kremena Stefanova using the relevant taxonomic literature (Mordukhay-Boltovskoy, F.D. (Ed.). 1968, 1969,1972). Taxon-specific mesozooplankton abundance: The collected material was analysed using the method of Domov (1959). Samples were brought to volume of 25-30 ml depending upon zooplankton density and mixed intensively until all organisms were distributed randomly in the sample volume. After that 5 ml of sample was taken and poured in the counting chamber for taxomomic identification and count. Copepods and Cladoceras were identified and enumerated; the other mesozooplankters were identified and enumerated at higher taxonomic level (commonly named as mesozooplankton groups). Large (> 1 mm body length) and not abundant species were calculated in whole sample. Counting and measuring of organisms were made in the Dimov chamber under the stereomicroscope to the lowest taxon possible. Taxonomic identification was done at the Institute of Fishery Resource by prof. Asen Konsulov and Institute of Oceanology by Prof. Asen Konsulov, Lyudmila Kamburska and Kremena Stefanova using the relevant taxonomic literature (Mordukhay-Boltovskoy, F.D. (Ed.). 1968, 1969,1972).

A magneto-mineralogical study of basalt at DSDP Leg 73 Holes

The basalts in Holes 519A, 522B, and 524 were studied for intensity of natural remanent magnetization, magnetic hysteresis, magnetic susceptibility, stability of isothermal remanence, and thermomagnetic behavior. Some of these properties are sensitive to both the composition and the microstructure of the magnetic minerals, others to composition only. Thus it is possible to separate the two effects and to trace the variation of effective magnetic grain size and degree of alteration within a lithologic unit or over a yet larger distance or time interval. The flow in Hole 519A is highly maghemitized at the top, the degree of maghemitization decreasing with depth in the flow. Effective grain size increases with increasing depth. Electron microprobe analysis of the titanomaghemite grains in these samples provides no support for the leaching out of iron during alteration. The pillows and flows in Hole 522B are distributed among a number of cooling units, and no systematic downhole variations are apparent. The inferred magneto-petrology is consistent with the cooling and alteration history that might be expected within the units. The upper and lower sills in Hole 524 are more uniform and have a larger concentration of well-developed magnetic mineral grains than the pillows and flows in Holes 519A and 522B. Maghemitization appears to have developed from the boundaries of the sills that are in contact with the sediments between the sills.

Dissolved organic matter molecular composition and concentrations from a large scale mesocosm study KOSMOS 2013 Kristineberg) on ocean acidification

Marine dissolved organic matter (DOM) represents one of the largest active carbon reservoirs on Earth. Changes in pool size or composition could have major impacts on the global carbon cycle. Ocean acidification is a potential driver for these changes because it influences marine primary production and heterotrophic respiration. Here we show that ocean acidification as expected for a 'business-as-usual' emission scenario in the year 2100 (900 µatm) does not affect the DOM pool with respect to its size and molecular composition. We applied ultrahigh-resolution mass spectrometry to monitor the production and turnover of 7,360 distinct molecular DOM features in an unprecedented long-term mesocosm study in a Swedish Fjord, covering a full cycle of marine production. DOM concentration and molecular composition did not differ significantly between present-day and year 2100 CO2 levels. Our findings are likely applicable to other coastal and productive marine ecosystems in general.