Contribution of Organic Matter Decomposition in Water Column to Oxygen Consumption in the Inner Part of the Ariake Sea

Abstract

The contribution of dissolved organic carbon （ DOC ） decomposition to oxygen consumption was estimated in the inner part of the Ariake sea. Oxygen consumption and decomposition of particulate organic carbon （ POC ） and DOC were estimated using the bottom water samples collected from two stations in the inner part of the Ariake sea from May to August 2018. The contribution of DOC decomposition to total organic carbon decomposition was about 10%. Although the contribution of organic matter decomposition to total oxygen consumption was 47.0-54.2% before the occurrence of hypoxia, the contribution of organic matter decomposition to total oxygen consumption was minor during the hypoxia. These results suggest that organic matter decomposition plays an important role in oxygen consumption before the occurrence of hypoxia, and DOC decomposition is one of the driving forces of hypoxia.