The CO 2 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 hydrothermal
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 fromthe soil and bubbling
emanations from the springs.