As a supplementary or the only water source in dry regions, dew plays a critical role in the survival of organisms. The new hydrological tracer17O-excess, with almost sole dependence on relative humidity, provides a new way to distinguish the evaporation processes and reconstruct the paleoclimate. Up to now, there is no published daily dew isotope record on δ2H, δ18O, δ17O, d-excess, and17O-excess. Here, we collected daily dew between July 2014 and April 2018 from three distinct climatic regions (i.e., Gobabeb in the central Namib Desert with desert climate, Nice in France with Mediterranean climate, and Indianapolis in the central United States with humid continental climate). The δ2H, δ18O, and δ17O of dew were simultaneously analyzed using a Triple Water Vapor Isotope Analyzer based on Off-Axis Integrated Cavity Output Spectroscopy technique, and then d-excess and17O-excess were calculated. This report presents daily dew isotope dataset under three climatic regions. It is useful for researchers to use it as a reference when studying global dew dynamics and dew formation mechanisms.
Tap water isotopic compositions could potentially record information on local climate and water management practices. A new water isotope tracer17O-excess became available in recent years providing additional information of the various hydrological processes. Detailed data records of tap water17O-excess have not been reported. In this report, monthly tap water samples (n = 652) were collected from December 2014 to November 2015 from 92 collection sites across China. The isotopic composition (δ2H, δ18O, and δ17O) of tap water was analyzed by a Triple Water Vapor Isotope Analyzer (T-WVIA) based on Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS) technique and two second-order isotopic variables (d-excess and17O-excess) were calculated. The geographic location information of the 92 collection sites including latitude, longitude, and elevation were also provided in this dataset. This report presents national-scale tap water isotope dataset at monthly time scale. Researchers and water resource managers who focus on the tap water issues could use them to probe the water source and water management strategies at large spatial scales.
more » « less- NSF-PAR ID:
- 10197739
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Scientific Data
- Volume:
- 7
- Issue:
- 1
- ISSN:
- 2052-4463
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Tropical islands are simultaneously some of the most biodiverse and vulnerable places on Earth. Water resources help maintain the delicate balance on which the ecosystems and the population of tropical islands rely. Hydrogen and oxygen isotope analyses are a powerful tool in the study of the water cycle on tropical islands, although the scarcity of long-term and high-frequency data makes interpretation challenging. Here, a new dataset is presented based on weekly collection of rainfall H and O isotopic composition on the island of O‘ahu, Hawai‘i, beginning from July 2019 and still ongoing. The data show considerable differences in isotopic ratios produced by different weather systems, with Kona lows and upper-level lows having the lowest δ 2 H and δ 18 O values, and trade-wind showers the highest. The data also show significant spatial variability, with some sites being characterized by higher isotope ratios than others. The amount effect is not observed consistently at all sites. Deuterium excess shows a marked seasonal cycle, which is attributed to the different origin and history of the air masses that are responsible for rainfall in the winter and summer months. The local meteoric water line and a comparison of this dataset with a long-term historical record illustrate strong interannual variability and the need to establish a long-term precipitation isotope monitoring network for Hawai‘i. Significance Statement The isotopic composition of water is often used in the study of island water resources, but the scarcity of high-frequency datasets makes the interpretation of data difficult. The purpose of this study is to investigate the isotopic composition of rainfall on a mountainous island in the subtropics. Based on weekly data collection on O‘ahu, Hawai‘i, the results improve our understanding of the isotopic composition of rainfall due to different weather systems, like trade-wind showers or cold fronts, as well as its spatial and temporal variability. These results could inform the interpretation of data from other mountainous islands in similar climate zones.more » « less
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Abstract Dew is one of the important moisture sources in many arid and semiarid regions. The knowledge of moisture origin of dew under various climatic conditions is still lacking. Isotopic variations can preserve information about moisture origin and formation mechanisms. Therefore, the isotopic compositions of dew and precipitation (δ2H, δ18O, δ17O,
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Abstract The isotopic composition of precipitation (δ18O, δ2H, and δ17O) is affected by evaporation and exchange as hydrometeors descend. These processes can significantly alter the isotopic ratio of precipitation relative to its initial condensation state in the cloud yet are exceedingly difficult to study in situ. The most widely utilized model for droplet‐atmosphere exchange was derived from controlled experiments where droplets were suspended by forced air in a narrow glass tube‐ a design that manipulated the structure of the boundary layer around the droplet. Here, we provide a novel experimental test of atmosphere‐hydrometeor isotopic exchange using the mechanism of acoustic levitation, where sound waves are projected vertically to levitate droplets in free‐flowing ambient air. We present results from a series of droplet levitation experiments where the droplets' surface temperatures were measured by a thermal camera and the background atmospheric isotope concentration was measured via cavity‐ringdown spectroscopy, providing a high degree of constraint on the fractionation conditions. We show that isotope enrichment of the suspended droplets met first order expectations based on existing models. However, to account for the slope of δ18O versus δ2H (i.e., the meteoric water line) and deuterium excess of the droplets as they evolved, we had to modify the existing model for droplet‐atmosphere exchange to account for the fact that some portion of the evaporative flux from the droplet remained present in the boundary layer around the droplet leading to an evolving feedback between droplet and the atmosphere‐that is, a quasi closed‐system effect. The isotopic enrichment of the boundary layer surrounding the droplet as a consequence of the closed‐system dynamics, drives more rapid δ18O isotope enrichment relative to δ2H of the droplet compared to what is predicted using an open system model. Although these were controlled experiments, they illustrate important dynamics regarding the isotopic signature of feedbacks between droplet evaporation and atmospheric humidity.
