Lignin and chemical elements in the surface layer of bottom sediments from the Kandalaksha Bay of the White Sea

Chemical composition of the upper layer of sediments (0-1 cm) in the Kolvits and Knazhaya inlets, and also in the deep-water part of the Kandalaksha Bay is considered. It is shown that silts are richer in Fe, TOC, and heavy metals, than sands. The highest concentration of these elements is found in sediments under mixing zones of riverine and sea waters. Correlations of P, Zn, Cd, and Cu with iron are high, and correlations of Pb and Cu with organic carbon are also high. Very high concentration of Pb in the Kandalaksha Bay indicate technogenic pollution of sediments. Lignin makes significant contribution to formation of organic matter in the sediments. Composition of lignin in bottom sediments of the Kandalaksha Bay is defined by composition of lignin in soils and aerosols. Vanillin and syringyl structures prevail in molecular composition of lignin in bottom sediments. Their sources are coniferous vegetations, soils, and mosses. Ratios of certain types of phenol compounds indicate pollution of the upper layer of sediments by technogenic lignin. Lead and copper correlate well with this technogenic lignin.

Mineral composition of 0.1-0.05 mm grain size fraction from the surface layer of bottom sediments in the West European province of the Atlantic Ocean

Rock material sampled from the Mir manned deep-sea submersibles and by dradges, grabs, and sediment cores over a vast area of the North Atlantic was analyzed to show that this material is of continental origin, unlike original rocks of the ocean floor. It is proved to be related to iceberg rafting during Quaternary glaciations. Independent data on distribution and composition of sandy and silty grains in sediment cores also support this relation to the recent glaciation. New criteria for identification of iceberg rock matter in pelagic sediments are presented on the base of analysis of all available data.

Ocean bottom seismometer sgy-files of refraction seismic profiles from Professor Logachev cruise TTR16/3

Over the last decade pockmarks have proven to be important seabed features that provide information about fluid flow on continental margins. Their formation and dynamics are still poorly constrained due to the lack of proper three dimensional imaging of their internal structure. Numerous fluid escape features provide evidence for an active fluid-flow system on the Norwegian margin, specifically in the Nyegga region. In June-July 2006 a high-resolution seismic experiment using Ocean Bottom Seismometers (OBS) was carried out to investigate the detailed 3D structure of a pockmark named G11 in the region. An array of 14 OBS was deployed across the pockmark with 1 m location accuracy. Shots fired from surface towed mini GI guns were also recorded on a near surface hydrophone streamer. Several reflectors of high amplitude and reverse polarity are observed on the profiles indicating the presence of gas. Gas hydrates were recovered with gravity cores from less than a meter below the seafloor during the cruise. Indications of gas at shallow depths in the hydrate stability field show that methane is able to escape through the water-saturated sediments in the chimney without being entirely converted into gas hydrate. An initial 2D raytraced forward model of some of the P wave data along a line running NE-SW across the G11 pockmark shows, a gradual increase in velocity between the seafloor and a gas charged zone lying at ~300 m depth below the seabed. The traveltime fit is improved if the pockmark is underlain by velocities higher than in the surrounding layer corresponding to a pipe which ascends from the gas zone, to where it terminates in the pockmark as seen in the reflection profiles. This could be due to the presence of hydrates or carbonates within the sediments.