MINOR AND TRACE-ELEMENT CHEMISTRY OF LAKE BAIKAL, ITS TRIBUTARIES, AND SURROUNDING HOT-SPRINGS

A Russian-American fieldwork effort on Lake Baikal, its tributaries, a nd surrounding hot springs was undertaken in June-July 1991. Here we r eport 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 ion s generally concur with the more extensive, time-averaged Russian data base; for the most part the homogeneously distributed major ions appea r to be at steady state and dominated by riverine throughputs in the l ake. Exceptions include Mg2+, which may be removed to a small extent ( less than or equal to 15% of its riverine flux) by hydrothermal activi ty, and Na+ and Cl-, which seem to be impacted by pollution. Of the mi nor and trace elements, V also seems subject to anthropogenic disturba nce. Other elements for which reliable data are available show conserv ative steady-state distributions (Li, Cr, Sr) or an subject to redistr ibution and removal within the lake (Ge, Al, Cu, Ni, Ba, U) as a resul t of involvement in a variety of particle cycling processes that tend to obscure non-natural influences. Chemical geothermometers for the fo ur hot springs sampled (Smeyney, Khakuci, Kotelnikovski, Davsha) indic ate 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, L i, Al, Ge, Sr, U) with respect to lake water were observed. Ge levels in spring waters are sufficiently enriched over lake waters that Ge co uld serve as a useful tracer of subaquatic hydrothermal waters.