The main producer of organic matter in Lake Baikal is diatoms, whose development largely depends on silica concentrations in the lake water. Silica is introduced to the lake from inflowing surface waters. The Selenga River, the main tributary of the lake, delivers ∼50% of the total surface water inflow and more than half of the chemical inputs to Lake Baikal. The average annual input of silica to the lake is ∼114 000 t during years when water level in the river approximates the long term average. The period under study (2001–2017), however, was characterized by exceptionally low water levels in the Selenga River and an annual average reduction of silica input to Lake Baikal up to 56 000 t. Since the beginning of the 21st century, the total deficit of silica input to the lake from the Selenga River is ∼650 000 t. Currently, the silica concentrations in the Selenga River Shoal have declined to values that limit the development of dominant diatom species in Lake Baikal.

贝加尔湖有机物的主要生产者是硅藻，硅藻的发展在很大程度上取决于湖水中二氧化硅的浓度。二氧化硅从流入的地表水引入湖中。塞伦加河是该湖的主要支流，向贝加尔湖提供了约50％的总地表水流入量和一半以上的化学投入。当河流中的水位接近长期平均水平时，每年向湖中添加的二氧化硅的年平均量约为11.4万吨。然而，本研究期（2001年至2017年）的特征是，塞伦加河的水位极低，贝加尔湖的二氧化硅年均输入量减少了56000吨。自21世纪初以来，从塞伦加河向湖中输入的二氧化硅总量约为650 000吨。目前，