Particulate organic carbon in the ocean
Most recently, I have been working with my Ph.D. advisor, Dr. Hilary Close, to assess the ubiquity of a lower euphotic zone minimum in δ13C values of particulate organic carbon (δ13C-POC) based on a compilation of previously published data. Many factors can influence δ13C-POC values, including photosynthetic isotopic fractionation, various sources of particulate organic carbon, and degradation. Statistical analysis showed that δ13C-POC values in the lower euphotic zone/below the mixed layer are statistically significantly different from values in the upper euphotic zone/mixed layer. This may indicate either spatial separation of organic matter due to differences in the phytoplankton community at each depth or substantial degradation/transformation over depth. You can read the paper here.
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