Collaborative Research: Quantifying past water table depth and hydroclimate with dissolved noble gas isotopes in groundwater

合作研究：利用地下水中溶解的惰性气体同位素量化过去的地下水位深度和水文气候

• 批准号: 1702704
• 负责人: Jeffrey Severinghaus
• 金额: $ 35.15万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-07-01 至 2020-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1702704&HistoricalAwards=false
• 关键词: Collaborative; Research; Quantifying; past; water

Water resources are a critical issue for agriculture in the arid parts of the US, and it is likely that water availability will be affected by future climate change, yet it remains difficult to predict the magnitude of future rainfall changes. The proposed research will develop a new and precise method for quantifying past changes in water table depth, using measurements of dissolved noble gas isotopes in ancient groundwater. This knowledge of past water table fluctuations will help illuminate the regional rainfall response to climate variations, and strengthen predictions by providing rigorous tests of rainfall models. The method is based on the demonstrated fact that heavy gases settle to the bottom of the stagnant column of air in the soil above the water table depth. The deeper the water table, the more extreme the enrichment of heavy isotopes, and these heavy isotopes become dissolved in the water thus preserving information about the water table depth in aquifers containing ancient groundwater. This groundwater is already routinely sampled to learn about past temperature from the abundance of the noble gases; the proposed research will add water table depth to the information that can be extracted from the samples.

水资源是美国干旱地区农业的一个关键问题，未来气候变化很可能会影响水资源的供应，但预测未来降雨量变化的幅度仍然很困难。这项拟议中的研究将开发一种新的精确方法，通过测量古代地下水中溶解的稀有气体同位素，来量化过去地下水位的变化。这种对过去地下水位波动的了解将有助于阐明区域降雨对气候变化的反应，并通过提供对降雨模型的严格检验来加强预测。该方法是基于已证明的事实，即重气体沉降到地下水位以上的土壤中停滞的空气柱的底部。地下水位越深，重同位素的富集程度就越极端，这些重同位素溶解在水中，从而保存了含有古代地下水的含水层中地下水位深度的信息。这些地下水已经被常规取样，以从丰富的惰性气体中了解过去的温度；拟议的研究将增加地下水位深度的信息，可以从样品中提取。

项目成果

Precise determination of Ar, Kr and Xe isotopic fractionation due to diffusion and dissolution in fresh water

精确测定淡水中由于扩散和溶解而引起的 Ar、Kr 和 Xe 同位素分馏

• DOI: 10.1016/j.epsl.2019.03.008
• 发表时间: 2019
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: Seltzer, Alan M.;Ng, Jessica;Severinghaus, Jeffrey P.
• 通讯作者: Severinghaus, Jeffrey P.

Deglacial water-table decline in Southern California recorded by noble gas isotopes

• DOI: 10.1038/s41467-019-13693-2
• 发表时间: 2019-12-16
• 期刊: NATURE COMMUNICATIONS
• 影响因子: 16.6
• 作者: Seltzer, Alan M.;Ng, Jessica;Severinghaus, Jeffrey P.
• 通讯作者: Severinghaus, Jeffrey P.

Steady state fractionation of heavy noble gas isotopes in a deep unsaturated zone: UZ NOBLE GAS ISOTOPIC FRACTIONATION

深层不饱和区重惰性气体同位素的稳态分馏：UZ 稀有气体同位素分馏

• DOI: 10.1002/2016wr019655
• 发表时间: 2017
• 期刊: Water Resources Research
• 影响因子: 5.4
• 作者: Seltzer, Alan M.;Severinghaus, Jeffrey P.;Andraski, Brian J.;Stonestrom, David A.
• 通讯作者: Stonestrom, David A.