The carbon and nutrient dynamics in Tokyo Bay:sewage maintenance alters carbon and nutrient cycling

Abstract

This article summarizes results of the study conducted on the cycling of carbon and nutrients in Tokyo Bay. Extensive surveys on the partial pressure of CO₂ in the bay showed that the bay acts as a strong net sink for atmospheric CO₂, as a result of active photosynthesis driven by nutrient loading from the land, which overwhelms the decomposition of terrestrial organic matter. This is because sewage treatment plants in the watershed remove most of the labile organic carbon and provide mainly recalcitrant organic carbon to the bay. Furthermore, nutrient concentrations in the bay significantly decreased from January 1989 to December 2015. These reflect the reduced loading of nutrients into the bay due to the implementation of advanced wastewater treatment techniques.