Sediment Parameters of Northwest Black Sea Shelf and Slope: Implications for Transport of Heavy Metals and Radionuclides

Abstract

In June 1990, sediment cores were obtained from several locations in the Northwest Black Sea shelf and slope by a joint US/USSR scientific team aboard the survey vessel R N VODYANITSKY. The goal of this investigation was to determine the distribution and levels of radioactivity resulting from the Chernobyl 1986 nuclear accident. The sediment was characterized for texture, mineral composition, redox state, heavy metals, and radionuclides. Correlations emerging from these data reveal paths of dispersal and transport of materials from river sources to deposition sites on the shelf and slope. Kaolinite in the clay mineral suite clearly reflects a dispersal pattern originating in the Danube River and progressing in an easterly direction across the shelf. Sand-size gypsum and the elemental heavy metals Zn, Cu, Cr, and Pb (probable industrial source) as well as the elements A1 and Mg (probable terrigenous source) also show a dispersal pattern from the Danube station location in an easterly direction across the shelf. The dispersal direction indicated by these materials is not in conflict with recent existing notions concerning the hydrology of the Northwest Black Sea. Barium anomalies at a midshelf location may be related to operations in the Lebada oil fields situated updrift. Heavy mineral dispersal reflect the Danube and Crimean Provinces established for the shelf and relate to terrestrial source areas. In addition, the heavy mineral monazite correlates with the radioactive Th 232 found most abundantly in the Crimean Province. Local anomalies of Mn, Fe and U in the sediment at station locations are related to redox (Eh) conditions and other factors. CS'"''~' data, reported by Curtis and Broadway (1991), correspond to transport and dispersal patterns implicit in the mineralogic, anthropogenic indicators, and sediment characteristics of the study area.

Partitioning of Cs-137 Between Sediment and Water From the Black Sea

“…equal to 28 and 24 respectively. Stations 11, 10 and 8 have ratios of 50, 51 and 49 respectively, There are few data points on which this interpretation can be based but it is strengthened by examining Figure 2 in Neiheisel et al (1992) in which the dispersion of kaolinite from the Danube is shown to include stations 4, 5 and 6. Station 4 is located near the mouth of the Danube River and represents the population with high percentages of organics and silt.…”