Reply to comment by R. Anderson on "Uranium-series disequilibrium, sedimentation, diatom frustules, and paleoclimate change in Lake Baikal"
No abstract available.
Earth and Planetary Science Letters↗
Geology topics
J. A. Robbins
Publications and source records attributed to J. A. Robbins.
A summary of the effects of mining and related activities on the sediment-trace element geochemistry of Lake Coeur d'Alene, Idaho, USA
During 1989 and 1990 a series of 12 gravity cores, and 150 surface grab samples were collected in Lake Coeur d'Alene, Idaho to determine trace element concentrations, partitioning and surface and subsurface distribution patterns in the bed sediments of the lake. In addition, selected subsamples from one core were analyzed for 117 Cs activity to begin to establish a trace element geochemical history for the lake. The intent was to try and relate the trace element concentrations and distributions in the sediment column to past and present mining and mining related activities in the area. Substantial portions of the surface and near-surface sediments in Lake Coeur d'Alene are markedly enriched in Ag, As, Cd, Hg, Pb, Sb and Zn, and somewhat enriched in Cu, Fe and Mn. Surface distribution patterns, as well as variations in the thickness of the trace element-rich subsurface sediments, indicate that the source of much of this enriched material is the Coeur d'Alene River. The similarity between the trace element-rich surface and subsurface sediments with respect to: their location, their bulk chemistry, and their trace element partitioning indicate that the sources and/or concentrating mechanisms causing the trace element enrichment in the lake sediments probably have been the same throughout their depositional history. An estimated 75 million metric tons of trace element-rich sediments have been deposited on or in the lakebed. Based on a Mt. St. Helens' ash layer from the 1980 eruption, ages estimated from 137 Cs activity, and the presence of 80 discernible and presumably annual layers in a core collected near the Coeur d'Alene River delta, indicate that the deposition of trace element-rich sediments began, at least in the Coeur d'Alene River delta, some time between 1895 and 1910, dates consistent with the onset of mining and ore-processing activities that began in the area in the 1880's.
Journal of Geochemical Exploration↗
The Effect of mining and related activities on the sediment-trace element geochemistry of Lake Coeur d'Alene, Idaho, U.S.A.; Part II, Subsurface sediments
During the summer of 1990, 12 gravity cores were collected in Lake Coeur d'Alene, Idaho, at various depths and in a variety of depositional environments. All core subsamples were analyzed to determine bulk chemistry and selected subsamples were analyzed for trace-element partitioning and (137)Cs activity. The purpose of these analyses was to determine the trace-element concentrations and distributions in the sediment column and to try to establish a trace-element geochemical history of the lake in relation to mining and mining-related discharge operations in the area. Substantial portions of the near-surface sediments in Lake Coeur d'Alene are markedly enriched in Ag, As, Cd, Hg, Pb, Sb, and Zn, and somewhat enriched in Cu, Fe, and Mn. Variations in the thickness of the trace element- rich sediments suggest that the source of much of this material is the Coeur d'Alene River. Calculated estimates indicate that there are some 75 million metric tons of trace element-rich sediments currently on/in the lakebed. Estimated trace-element masses in excess of those caused by non-mining-related sources, range from a high of 468,000 metric tons of Pb to a low of 260 metric tons of Hg. The similarity between the trace element-rich surface and subsurface sediments as regards their: (1) location; (2) bulk chemistry; (3) interelement relationships; and (4) trace-element partitioning indicate that the sources and/or concentrating mechanisms causing the trace-element enrichment in the lake probably have been the same throughout their depositional history. Based on Mt. St. Helens' ash layer from the 1980 eruption, ages estimated from (137)Cs activity, and the presence of 80 discernible and presumably annual layers in a core collected near the Coeur d'Alene River delta, it appears that deposition rates for the trace element-rich sediments varied from 2.1 to 1.3 cm/yr. These data also indicate that the deposition of trace element-rich sediments began, at least in the Coeur d'Alene River delta, sometime between 1895 and 1910, dates consistent with the onset of mining and ore-processing activities in the area which began in the 1880's.
Open-File Report↗