Minor and trace element chemistry of Lake Baikal, its tributaries, and surrounding hot springs

A Russian-American fieldwork effort on Lake Baikal, its tributaries, and surrounding hot springs was undertaken in June-July 1991. Here we report on aspects of major ion (Ca2+, Mg2+, Na+, K+, Aile, Cl-, SO42-) and several minor and trace element (Li isotopes, Sr isotopes, Ba, Al, V, Cr, Ni, Cu, Ge, Cd, Hg, U) cycles. Our riverine data for major ions generally concur with the more extensive, time-averaged Russian database; for the most part the homogeneously distributed major ions appear to be at steady state and dominated by riverine throughputs in the lake. Exceptions include Mg2+, which may be removed to a small extent (less than or equal to 15% of its riverine flux) by hydrothermal activity, and Na+ and Cl-, which seem to be impacted by pollution. Of the minor and trace elements, V also seems subject to anthropogenic disturbance. Other elements for which reliable data are available show conservative steady-state distributions (Li, Cr, Sr) or an subject to redistribution and removal within the lake (Ge, Al, Cu, Ni, Ba, U) as a result of involvement in a variety of particle cycling processes that tend to obscure non-natural influences. Chemical geothermometers for the four hot springs sampled (Smeyney, Khakuci, Kotelnikovski, Davsha) indicate subsurface reaction temperatures ranging from 70 to 150 degrees C and converging to smaller ranges (+/-15 degrees C) for a given spring. Both depletions (Mg, Ba, Cu, Ni, Sr, U) and enrichments (Na, K, Cl, Li, Al, Ge, Sr, U) with respect to lake water were observed. Ge levels in spring waters are sufficiently enriched over lake waters that Ge could serve as a useful tracer of subaquatic hydrothermal waters.