Seasonal and spatial variation in the denitrifying activity in estuarine and lagoonal sediments

• Published in: Journal of oceanography Vol. 66; no. 1; pp. 155 - 160
• Main Authors: Senga, Yukiko, Okumura, Minoru, Seike, Yasushi
• Format: Journal Article
• Language: English
• Published: Dordrecht Dordrecht : Springer Netherlands 01.02.2010; Springer Netherlands; Springer Nature B.V
• Subjects: Brackish; coastal area; Denitrification; distance from the sea; Earth and Environmental Science; Earth Sciences; Estuaries; estuary; Freshwater; Freshwater & Marine Ecology; Geochemistry; lagoon; Oceanography; Sediments; Short Contribution; INW, Japan, Honshu, Shimane Prefect., Matsue, Shinji L; distance from the sea; Denitrification; coastal area; estuary; lagoon
• ISSN: 0916-8370; 1573-868X
• DOI: 10.1007/s10872-010-0013-0

We have elucidated the seasonal and spatial variation in the potential denitrifying activity in estuarine and coastal lagoonal sediments in Lakes Shinji and Nakaumi, Japan. The denitrifying activity increased from summer through autumn and was positively correlated with the temperature of the overlying water at all sites except one, where the bottom was always more reductive than at the other sites and there was no NO₃ ⁻ as a substrate for denitrification from spring to autumn. Moreover, the relationship between the denitrifying activity and the distance from the sea showed different trends in estuarine and lagoonal sediments. These spatial differences indicate that different factors regulate the denitrification in estuarine and lagoonal sediments. Denitrifying activity in estuarine sediment was regulated by the discharge of freshwater containing NO₃ ⁻ or organic matter, while in the lagoonal sediments the occurrence of nitrification via the intrusion of oxic seawater into the reductive sediment appears to be a key requirement for the process of denitrification. Therefore, the denitrifying activity in the lagoonal sediment appears to be greater near the sea. Water intrusion is one of the key factors controlling denitrification in coastal marine ecosystems by affecting the supply of substrate available for denitrification.