Congratulations to Dr. Xi Lu, who just published her latest paper, “Evaluation of the moderate DI13C isotope enrichment method for measuring photochemical mineralization of marine dissolved organic carbon” in Limnology and Oceanography: Methods.
Dr. Lu used monte carlo simulations to study the limits of moderate isotope dilution to measure the rates at which organic matter that is dissolved in seawater (DOM) is naturally converted to carbon dioxide when exposed to sunlight, i.e., the rates of “photochemical mineralization”. This is a unique and promising application that was originally developed by Dr. Leanne Powers and colleagues (2017)
This study is important because photochemical mineralization is presently believed to be the fastest natural process that destroys the oldest organic matter found in seawater–molecules that are thousands of years old! However, additional high precision measurements of the reaction rates are needed to test whether this is true. Aside from fundamental improvements in mass spectrometry, Dr. Lu’s work suggests that 1) using fractional isotopic abundances in calculations, 2) partially stripping the original dissolved inorganic carbon (DIC) from seawater and enriching the remaining DIC to higher 13C abundances prior to irradiating with sunlight, and 4) maximizing yields should improve the overall measurement precision and decrease the detection limit.
How did she figure this out? Read all about it in L&O: Methods, available here (and don’t forget to check out the supplemental materials)