Evaluation of the moderate DI 13 C isotope enrichment method for measuring photochemical mineralization of marine dissolved organic carbon
Evaluation of the moderate DI 13 C isotope enrichment method for measuring photochemical mineralization of marine dissolved organic carbon
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中等DI 13 C同位素富集法测量海洋溶解有机碳光化学矿化作用的评价
DOI：
10.1002/lom3.10450
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Beaupré, Steven
中科院分区：
文献类型：
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作者：
Lu, Xi;Beaupré, Steven
Powers等人（2017）的中度DI13 C同位素富集（MoDIE）方法是一种有前途的方法，可以精确测量水样中溶解有机碳（DOC）的光化学矿化，而不会显著改变样品的pH值或有机碳库。在这里，我们评估了MoDIE方法的分析不确定性，并使用Monte Carlo模拟来优化实验设计，以最精确地测量光化学产生的溶解无机碳（DIC）（DIChν）。从分析上讲，我们建议使用质量守恒的精确表达式计算DIChv的产率，这在本质上减少了误差和不确定性。在方法学上，MoDIE方法的总体不确定性和检测限可以通过部分剥离原始DIC池、用更多的DI13C富集残留DIC以及经由更长的照射增加DI13C的产率来显著降低。在仪器方面，需要更精确地测量辐照前后富集的δ 13 C值，以进一步提高DIChν浓度测定的精度。通过优化的MoDIE方法获得的更高精度的DIChv测量值可以提高我们对DOC光化学矿化的理解，从而提高海洋DOC的收支。随着未来MoDIE实验的测量和相关不确定性的可用，这里报告的优化和检测限将变得更加精确。
The moderate DI13C isotope enrichment (MoDIE) method by Powers et al. (2017) is a promising method to precisely measure the photochemical mineralization of dissolved organic carbon (DOC) in water samples without dramatically altering a sample's pH or organic carbon pool. Here, we evaluated the analytical uncertainties of the MoDIE method and used Monte Carlo simulations to optimize the experimental design for the most precise measurements of dissolved inorganic carbon (DIC) that is produced photochemically (DIChν). Analytically, we recommend calculating yields of DIChvwith an exact expression of conservation of mass that intrinsically reduces error and uncertainty. Methodologically, the overall uncertainty and detection limit of the MoDIE method can be significantly reduced by partially stripping away the original DIC pool, enriching the residual DIC with more DI13C, and increasing the yields of DIChvvia longer irradiation. Instrumentally, more precise measurements of enriched δ13C values before and after irradiation are needed to further improve the precision of DIChνconcentration determinations. Higher precision DIChvmeasurements via the optimized MoDIE method can improve our understanding of the photochemical mineralization of DOC and thus the budget of marine DOC. The optimizations and detection limits reported here will become more refined as measurements and associated uncertainties from future MoDIE experiments become available.