Carbon budget in eutrophic lake, Lake Tega

Abstract

The observation of organic carbon (TOC) was conducted throughout year in the water of Lake Tega in Japan, identified as a eutrophic lake. Higher TOC inventory was found in spring, and TOC inventory was correlated with organic carbon production rate. Total annual riverine outflow of TOC was approximately 300MgC larger than the inflow of TOC. Based on the results of inorganic and organic carbon in Lake Tega, we made a comprehensive evaluation of the role of this lake to the atmospheric CO₂ concentration. Lake Tega releases CO₂ to the atmosphere from lake water at a twice rate of the mean rate of global lakes. On the other hand, this lake self-constrains the CO₂ release rate due to changing inorganic carbon into organic matter which cannot exchange to the atmospheric CO₂, by the higher productivity.