Net additions of recalcitrant dissolved organic carbon in the deep Atlantic Ocean

• Main Authors: Romera-Castillo, C. (Cristina), Álvarez, M. (Marta), Pelegrí-Llopart, J.L. (José Luis), Hansell, D.A., Álvarez-Salgado, X.A. (Xosé Antón)
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union (AGU) 2019
• Subjects: North Atlantic
• Online Access: http://hdl.handle.net/10508/14878; https://rss.onlinelibrary.wiley.com/doi/am-pdf/10.1029/2018gb006162

Most dissolved organic carbon (DOC) sequestered in the deep ocean has residence times of decades to thousands of years, with clear implications for climate regulation, though some net removal is typically observed with increasing water mass age. Here, a high‐quality‐high‐resolution data set has allowed us to identify net additions of recalcitrant DOC in specific water masses of the deep South Atlantic. Overall, the South Atlantic is a net source of recalcitrant DOC, adding 0.027 ± 0.019 Pg C/year, while the North Atlantic is a net sink that removes 0.298 ± 0.141 Pg C/year. We find that the balance of addition/removal of recalcitrant DOC depends not only on the origin but also on the temperature, age, and depth of the water masses that circulate and mix in the Atlantic Ocean. Future changes in the water mass composition and circulation patterns due to climate change would eventually affect that balance, altering the carbon cycle.