TY - JOUR
T1 - Continuous shipboard measurements of oceanic δ18O, δD and δ13CDIC along a transect from New Zealand to Antarctica using cavity ring-down isotope spectrometry
AU - Bass, Adrian M.
AU - Munksgaard, Niels C.
AU - O'Grady, Damien
AU - Williams, Michael J M
AU - Bostock, Helen C.
AU - Rintoul, Stephen R.
AU - Bird, Michael I.
PY - 2014/9
Y1 - 2014/9
N2 - Cavity ring-down spectrometers, with automated sampling interfaces, were deployed to allow measurements of water isotopes (δ18O, δD) and dissolved inorganic carbon (δ13CDIC) stable isotope ratios at high temporal resolution along a transect from New Zealand to the Antarctic continental shelf. Measurements every 10 min for δ18O and δD, 15 min for DIC yielded 2499 and 2289 discrete measurements respectively. High resolution data enabled the delineation of water mass boundaries as well as revealing insights into surface hydrological and biological processes. δ18O, δD, and δ13CDIC decreased southwards, dropping by approximately 1.0‰, 7.0‰, and 0.5‰, respectively. Though the decline in δ13CDIC with latitude was generally linear, the drop in δ18O and δD was punctuated by areas of rapid, significant change corresponding to the Sub-Tropical, Sub-Antarctic and Polar Fronts. North of the Sub-Antarctic Front (approx. 54.5°S) the dominant control on water and DIC isotopes was the precipitation–evaporation balance and the contribution of upwelling waters, respectively. Further south, in close proximity to the sea ice and on the Antarctic shelf, water isotope values were more variable and predominantly influenced by the melting/freezing of sea-ice coupled to inputs from glacial/snow melt water. Local increases in δ13CDIC were likely due to photosynthetic enrichment of the DIC pool. Using this new instrumentation has provided one of the most comprehensive oceanic transect data sets yet achieved and illustrates the potential of these methods to delineate discrete water masses and advance our knowledge of both water and inorganic carbon cycling processes in the ocean. This methodology, combining high-resolution isotopic measurements with hydrographic data, has significant benefits in modelling water mixing in locations with multiple sources and controlling processes.
AB - Cavity ring-down spectrometers, with automated sampling interfaces, were deployed to allow measurements of water isotopes (δ18O, δD) and dissolved inorganic carbon (δ13CDIC) stable isotope ratios at high temporal resolution along a transect from New Zealand to the Antarctic continental shelf. Measurements every 10 min for δ18O and δD, 15 min for DIC yielded 2499 and 2289 discrete measurements respectively. High resolution data enabled the delineation of water mass boundaries as well as revealing insights into surface hydrological and biological processes. δ18O, δD, and δ13CDIC decreased southwards, dropping by approximately 1.0‰, 7.0‰, and 0.5‰, respectively. Though the decline in δ13CDIC with latitude was generally linear, the drop in δ18O and δD was punctuated by areas of rapid, significant change corresponding to the Sub-Tropical, Sub-Antarctic and Polar Fronts. North of the Sub-Antarctic Front (approx. 54.5°S) the dominant control on water and DIC isotopes was the precipitation–evaporation balance and the contribution of upwelling waters, respectively. Further south, in close proximity to the sea ice and on the Antarctic shelf, water isotope values were more variable and predominantly influenced by the melting/freezing of sea-ice coupled to inputs from glacial/snow melt water. Local increases in δ13CDIC were likely due to photosynthetic enrichment of the DIC pool. Using this new instrumentation has provided one of the most comprehensive oceanic transect data sets yet achieved and illustrates the potential of these methods to delineate discrete water masses and advance our knowledge of both water and inorganic carbon cycling processes in the ocean. This methodology, combining high-resolution isotopic measurements with hydrographic data, has significant benefits in modelling water mixing in locations with multiple sources and controlling processes.
KW - Antarctica
KW - Dissolved inorganic carbon
KW - Hydrogen isotopes
KW - Oxygen isotopes
KW - Polar front
KW - Sea-ice
KW - Southern ocean
KW - Sub-Antarctic front
KW - Sub-tropical front
UR - http://www.scopus.com/inward/record.url?scp=84899784362&partnerID=8YFLogxK
U2 - 10.1016/j.jmarsys.2014.04.003
DO - 10.1016/j.jmarsys.2014.04.003
M3 - Article
VL - 137
SP - 21
EP - 27
JO - Journal of Marine Systems
JF - Journal of Marine Systems
SN - 0924-7963
ER -