TY JOUR TI Current Water Chemical Composition of the Kizhi Skerries of Lake Onego and Its Dynamics Over the Last 30 Years KW Water chemical composition KW organic matter KW nutrients KW pollutants KW climate change KW anthropogenic impact KW Lake Onega JO Russian Journal of Earth Sciences AU Zobkova, M.V. PY 2026 IS 26 PB Geophysical Center of the Russian Academy of Sciences