Dissolved inorganic Radiocarbon content of the Western Coral sea: Implications for Intermediate and Deep Water Circulation

• Published in: Radiocarbon
• Main Authors: Servettaz, Aymeric PM, Yokoyama, Yusuke, Hirabayashi, Shoko, Kienast, Markus, Miyairi, Yosuke, Mohtadi, Mahyar
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2019
• Subjects: Antarc*; Antarctic
• Online Access: http://dx.doi.org/10.1017/rdc.2019.122; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S003382221900122X

ABSTRACT The South Pacific Ocean contributes to the global carbon cycle by exchanging CO 2 between the atmosphere and intermediate to deep water masses. The path of the Antarctic Intermediate Water (AAIW) in the South Pacific gyre has been inferred from salinity, oxygen, and nutrient measurements, but radiocarbon ( 14 C) measurements—a direct tracer of the carbon cycle—remain sparse. Here, we present the first radiocarbon profiles in the western Coral Sea and compare our measurements with South Pacific stations from GLODAPv2, a database of ocean hydrochemistry. Surface and subsurface waters in the Coral Sea cannot be attributed to a single source based on their Δ 14 C signatures, and we observe a penetration of bomb-produced 14 C. AAIW in the western Coral Sea shows Δ 14 C values comparable to those in the South Pacific gyre, consistent with circulation of AAIW in the lower part of the southern equatorial current. The deep waters of the western Coral Sea have significantly higher 14 C than the South Pacific at the same isopycnal, consistent with a northward intrusion of Circumpolar Deep Water from the Tasman Sea, along with a westward influx of deep waters from the Central Pacific. In accordance with silicate concentrations published previously, this shows the dual origin of deep waters in the Coral Sea.