Abstract
Fluxes of nitrogen, phosphorus and dissolved organic carbon (DOC) from benthic sediments were investigated in two connected brackish lakes, Shinji and Nakaumi. Fluxes were estimated in laboratory experiments using intact sediment cores that had been collected from two sites in each of the lakes. In aerobic conditions, nitrate (NO3--N) was released from the sediment in western Lake Shinji. In the center of Lake Nakaumi, no nitrogen flux was observed from the sediment under aerobic conditions, and the sediment flux in the Yonago embayment was substantially less than that of Lake Shinji. The release of phosphate (PO43--P) from benthic sediments in Lake Shinji was observed under both anaerobic and aerobic conditions. In anaerobic conditions, sediment flux of both nitrogen and phosphorus increased substantially.
Additionally, we found that in both lakes, the flux of DOC under anaerobic conditions was several fold higher than under aerobic conditions.
