3 research outputs found
An Ultrahigh Precision, High-Frequency Dissolved Inorganic Carbon Analyzer Based on Dual Isotope Dilution and Cavity Ring-Down Spectroscopy
We
present a novel method for continuous and automated shipboard
measurements of dissolved inorganic carbon concentration ([DIC]) in
surface water. The method is based on dual isotope dilution and cavity
ring-down spectroscopy (DID-CRDS). In this method, seawater is continuously
sampled and mixed with a flow of NaH<sup>13</sup>CO<sub>3</sub> solution
that is also enriched in deuterated water (the spike). The isotopic
composition of CO<sub>2</sub> (δ<sup>13</sup>C<sub>spiked_sample</sub>) derived from the DIC in the mixture, and the D/H ratio of the mixed
water (δD<sub>spiked_sample</sub>), are measured by CRDS analyzers.
The D/H of the water in the mixture allows accurate estimates of the
mixing ratio of the sample and the spike. [DIC] of the sample is then
calculated from the mixing ratio, [DI<sup>13</sup>C] of the spike,
and δ<sup>13</sup>C<sub>spiked_sample</sub>. In the laboratory,
the precision of the method is <0.02% (±0.4 μmol kg<sup>–1</sup> when [DIC] = 2000 μmol kg<sup>–1</sup>). A shipboard test was conducted in the Delaware Bay and Estuary.
For 2 min average [DIC], a precision of <0.03% was achieved. Measurements
from the DID-CRDS showed good agreement with independent measurements
of discrete samples using the well-established coulometric method
(mean difference = −1.14 ± 1.68 μmol kg<sup>–1</sup>), and the nondispersive infraredÂ(NDIR)-based methods (mean difference
= −0.9 ± 4.73 μmol kg<sup>–1</sup>)
C++ code needed for running R code
C++ code needed for running R cod
R code used in Bolstad et al. (2017, Nature Ecology & Evolution)
R code used in Bolstad et al. (2017, Nature Ecology & Evolution