87Sr/86Sr of Lake Baikal: Evidence for rapid homogenization of water

Abstract

We provide an extended 87Sr/86Sr database for the water of Lake Baikal collected along the lake and within its bays at a depth range from the surface down to 1366 m, the major tributary rivers, lake animals, and atmospheric precipitation. The water of open Lake Baikal, the Little Sea (Maloe More) Strait, and large bays are characterized by a uniform 87Sr/86Sr = 0.7086266 ± 0.0000045 (n = 44, uncertainty at 95% confidence interval). Major volumetric contributors of water to the lake (the eastern rivers and precipitation) are only slightly different from the lake value in terms of 87Sr/86Sr. In the western rivers, 87Sr/86Sr is much higher, but due to their small incoming volume, their contribution is rapidly diluted by the water currents of the lake. The exception is water with high 87Sr/86Sr from isolated Mukhor Bay at the inland end of the Little Sea Strait and water above the underwater discharge of hydrothermal springs. Benthic and pelagic Lake Baikal animals have 87Sr/86Sr similar to the values of the open lake, supporting lake water homogenization. The modelled budget of Sr suggests that 86 ± 14% of input Sr is stored in the waters of Lake Baikal. In other words, according to the estimations some Sr (from 0 to 28%) may be precipitated at the lake bottom by chemical and biochemical processes.