The CO2 flux from hydrothermal systems of the Karymsky volcanic Centre, Kamchatka

The CO2 flux provided by the hydrothermal activity within the Karymsky Volcanic Centre, Kamchatka, was measured, and the CO2 balance of the Karymsky caldera lake was estimated in the framework of a Deep Carbon Observatory (DCO) project. The Karymsky Volcanic Centre located in the SE of the Kamchatka Peninsula, in the middle of the modern volcanic front consists of two calderas, hosts a caldera lake and is characterized by hydro thermal activity that is manifested at several thermal fields. Within the Akademii Nauk (AN) caldera which is filled by a caldera lake, the Akademii Nauk springs discharge boiling water into the lake. The lake is drained by the Karymsky River that then crosses the caldera of the Karymsky volcano (Karymsky caldera) and drains the thermal field of CO2-rich Karymsky springs. The lake after the 1996 sublimnic eruption is in a steady-state condition with the total dynamic CO2 budget of about 4 t/day, and has a total amount of CO2 stored inside of the lake of around 8000 t. The thermal springs of the Karymsky caldera drained by the Karymsky River enrich the river in dissolved carbon species. A total CO2 output of 320 t/day from both Karymsky Centre calderas was estimated, carrying around 130 t/day carbon species (expressed as CO2) as dissolved species (HCO3 and CO2(aq)), and emitting to the atmosphere around 190 t/day of CO2 as the diffusion flux from the soil and bubbling emanations from the springs.