Description of a global marine particulate organic carbon-13 isotope data set

• Published in: Earth System Science Data
• Main Authors: Verwega, Maria-Theresia, Somes, Christopher J., Schartau, Markus, Tuerena, Robyn Elizabeth, Lorrain, Anne, Oschlies, Andreas, Slawig, Thomas
• Format: Text
• Language: English
• Published: 2021
• Subjects: Arctic; Arctic Ocean; Southern Ocean; Phytoplankton
• Online Access: https://doi.org/10.5194/essd-13-4861-2021; https://essd.copernicus.org/articles/13/4861/2021/

Marine particulate organic carbon stable isotope ratios ( δ 13 C POC ) provide insights into understanding carbon cycling through the atmosphere, ocean and biosphere. They have for example been used to trace the input of anthropogenic carbon in the marine ecosystem due to the distinct isotopically light signature of anthropogenic emissions. However, δ 13 C POC is also significantly altered during photosynthesis by phytoplankton, which complicates its interpretation. For such purposes, robust spatio-temporal coverage of δ 13 C POC observations is essential. We collected all such available data sets and merged and homogenized them to provide the largest available marine δ 13 C POC data set ( https://doi.org/10.1594/PANGAEA.929931 Verwega et al. , 2021 ). The data set consists of 4732 data points covering all major ocean basins beginning in the 1960s. We describe the compiled raw data, compare different observational methods, and provide key insights in the temporal and spatial distribution that is consistent with previously observed large-scale patterns. The main different sample collection methods (bottle, intake, net, trap) are generally consistent with each other when comparing within regions. An analysis of 1990s median δ 13 C POC values in a meridional section across the best-covered Atlantic Ocean shows relatively high values ( <math xmlns="http://www.w3.org/1998/Math/MathML" id="M11" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>≥</mo><mo>-</mo><mn mathvariant="normal">22</mn></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="32pt" height="11pt" class="svg-formula" dspmath="mathimg" md5hash="560d990da7c2829292cafe814d2cfdc0"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="essd-13-4861-2021-ie00001.svg" width="32pt" height="11pt" src="essd-13-4861-2021-ie00001.png"/></svg:svg> ‰) in the low latitudes ( <30 ∘ ) trending towards lower values in the Arctic Ocean ( <math xmlns="http://www.w3.org/1998/Math/MathML" id="M14" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>∼</mo><mo>-</mo><mn mathvariant="normal">24</mn></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="32pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="47ddd52e370c2a6e8b9006ebb05b218c"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="essd-13-4861-2021-ie00002.svg" width="32pt" height="10pt" src="essd-13-4861-2021-ie00002.png"/></svg:svg> ‰) and Southern Ocean ( <math xmlns="http://www.w3.org/1998/Math/MathML" id="M15" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>≤</mo><mo>-</mo><mn mathvariant="normal">28</mn></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="32pt" height="11pt" class="svg-formula" dspmath="mathimg" md5hash="72864cfbe94f5621d7358b3ba7747c08"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="essd-13-4861-2021-ie00003.svg" width="32pt" height="11pt" src="essd-13-4861-2021-ie00003.png"/></svg:svg> ‰). The temporal trend since the 1960s shows a decrease in the median δ 13 C POC by more than 3 ‰ in all basins except for the Southern Ocean, which shows a weaker trend but contains relatively poor multi-decadal coverage.