Measurement of δ¹⁸O, δ¹⁷O, and ¹⁷O-excess in Water by Off-Axis Integrated Cavity Output Spectroscopy and Isotope Ratio Mass Spectrometry

Abstract

Stable isotopes of water have long been used to improve understanding of the hydrological cycle, catchment hydrology, and polar climate. Recently, there has been increasing interest in measurement and use of the less-abundant 17O isotope in addition to 2H and 18O. Off-axis integrated cavity output spectroscopy (OA-ICOS) is demonstrated for accurate and precise measurements δ18O, δ17O, and 17O-excess in liquid water. OA-ICOS involves no sample conversion and has a small footprint, allowing measurements to be made by researchers collecting the samples. Repeated (514) high-throughput measurements of the international isotopic reference water standard GISP demonstrate the precision and accuracy of OA-ICOS: δ18OVSMOW-SLAP =−24.74 ± 0.07 ‰ (1σ) and δ17OVSMOW-SLAP = −13.12 ± 0.05 ‰ (1σ). For comparison, the IAEA value for δ18OVSMOW-SLAP is −24.76 ± 0.09 ‰ (1σ) and an average of previously reported values for δ17OVSMOW-SLAP is −13.12 ± 0.06 ‰ (1σ). Multiple (26) high-precision measurements of GISP provide a 17O-excessVSMOW-SLAP of 23 ± 10 per meg (1σ); an average of previously reported values for 17O-excessVSMOW-SLAP is 22 ± 11 per meg (1σ). For all these OA-ICOS measurements, precision can be further enhanced by additional averaging. OA-ICOS measurements were compared with two independent isotope ratio mass spectrometry (IRMS) laboratories and shown to have comparable accuracy and precision as the current fluorination-IRMS techniques in δ18O, δ17O, and 17O-excess. The ability to measure accurately δ18O, δ17O, and 17O-excess in liquid water inexpensively and without sample conversion is expected to increase vastly the application of δ17O and 17O-excess measurements for scientific understanding of the water cycle, atmospheric convection, and climate modeling among others.

Evaporation induced 18O and 13C enrichment in lake systems: A global perspective on hydrologic balance effects

“…Determining the extent to which source water O and C isotopic compositions are modified by evaporation can now be determined with relative ease. Triple-oxygen isotope analysis of water, an excellent indicator of evaporation effects , is becoming more common as researchers begin utilizing current generation off-axis integrated cavity output spectrometers (Berman et al, 2013) and high sensitivity isotope ratio mass spectrometers (Barkan and Luz, 2005), and d 13 C-DIC analyses are similarly more accessible to the geochemical research community (e.g. Bass et al (2014)).…”

Vapor hydrogen and oxygen isotopes reflect water of combustion in the urban atmosphere

“…Quantitative adoption of this approach will be challenging and require a more thorough understanding of controls on d for water emitted from different combustion processes (including O-bearing fuels) as well as accounting for other sources and sinks for boundary layer vapor or the use of independent tracers to help separate combustion and noncombustion influences on d values. One such tracer may be 17 O (28, 35), which, through recent advances in laser spectroscopy, is now a potential candidate for inclusion in atmospheric monitoring (36,37). With such information, d may prove to be a useful complement to other tracers used in partitioning urban emissions, such as δ 13 CO 2 and [CO] (17,38).…”

Water vapor δ2H, δ18O and δ17O measurements using an off‐axis integrated cavity output spectrometer – sensitivity to water vapor concentration, delta value and averaging‐time

“…Recently, there has been growing interest in a new hydrological tracer δ 17 O, accompanied by the development of high-precision analytical methods [9,10] . Similar to δ 2 H and δ 18 O, δ 17 O can be used to infer the degree of isotope enrichment during transpiration [11] , serve as tracer in different water bodies (e.g., meteoric water and ice cores) [12][13][14] , and characterize evaporative regimes.…”

“…In addition, the technique requires water to be converted to O2 rather than CO2 or CO, which is a laborious process [19][20][21] . As a result, δ 17 O measurements derived from the IRMS technique are complicated, expensive and timeconsuming, and can only be done in a small number (< 10) of laboratories worldwide [9,10,21,22] .…”