Concentrations of As and other chemical elements in bottom sediments of the Baltic Sea

As is less toxic than Hg, Cd, Pb, Se, Zn, and Cu. The As clarke for clays and shales is 10 ppm. Our samples of bottom sediments from Kurshskii Bay were determined to contain from 15 to 26 ppm As and up to 34 ppm As in the vicinity of the Neman River mouth. Elevated As concentrations (50-114 ppm) were detected in four columns of subsurface bottom sediments (at depths of 10-65 cm) from the Vistula Lagoon. Elevated As concentrations (50-180 ppm) were also found in a few surface samples of sand from the Gdansk Deep near oil platform D-6. These sediments are either partly contaminated with anthropogenic As or contain Fe sulfides and glauconite, which can concentrate As and contain its elevated concentrations. The As concentration in columns of bottom sediments from the Gulf of Finland were at the natural background level (throughout the columns) typical of the area (9-34 ppm). We repeatedly detected very high As concentrations (up to 227 ppm As) in politic ooze from Bornholm Deep, in the vicinity of the sunken vessel with chemical weapons. The sources of elevated As concentrations in the Baltic Sea are the following: (1) chemical weapon (CW) material buried in the floor of the Baltic Sea; (2) As-bearing pesticides, agricultural mineral fertilizers, and burned coal and other fuels; (3) kerogen-bearing Ordovician rocks exposed on the bottom; and (4) As-rich Fe sulfides brought to the area together with construction sand and gravel. This mixture was used in paper production and for the construction of hydraulic engineering facilities in the Vistula Lagoon in the early 20th century and later caused the so-called lagoon disease.

Chemical composition of phosphorite nodules off Peru

Phosphorite nodules collected during Cruise 8 of R/V Dmitry Mendeleev off the Peruvian coast are represented by three lithologic types: friable, compacted, and solid. As the nodules are progressively compacted, contents of phosphate components increase and of non-phosphate components decrease. Isotope composition of uranium in the friable nodules is the same as in ocean water, and diatoms contained in the nodules are represented by recent species indicating Late Quaternary age of the nodules.

(Table 1) Chemical composition of magmatic rocks from a submarine seamount

Petrography of magmatic rocks collected from a submarine seamount on the Mid-Pacific Rise is briefly characterized. Variety of petrographic types of effusive rocks and xenoliths contained in them indicates complexity of geologic development and distinctive structure of the oceanic crust in the area under study.