干旱区生态环境知识资源中心(Arid): The triple argon isotope composition of groundwater on ten-thousand-year timescales

Arid

DOI	10.1016/j.chemgeo.2021.120458
	The triple argon isotope composition of groundwater on ten-thousand-year timescales
	Seltzer, Alan M.; Krantz, John A.; Ng, Jessica; Danskin, Wesley R.; Bekaert, David V.; Barry, Peter H.; Kimbrough, David L.; Kulongoski, Justin T.; Severinghaus, Jeffrey P.
通讯作者	Seltzer, AM (corresponding author), Woods Hole Oceanog Inst, Marine Chem & Geochem Dept, Woods Hole, MA 02543 USA.
来源期刊	CHEMICAL GEOLOGY
ISSN	0009-2541
EISSN	1872-6836
出版年	2021
卷号	583
英文摘要	Understanding the age and movement of groundwater is important for predicting the vulnerability of wells to contamination, constraining flow models that inform sustainable groundwater management, and interpreting geochemical signals that reflect past climate. Due to both the ubiquity of groundwater with order ten-thousand-year residence times and its importance for climate reconstruction of the last glacial period, there is a strong need for improving geochemical dating tools on this timescale. Whereas C-14 of dissolved inorganic carbon and dissolved He-4 are common age tracers for Late Pleistocene groundwater, each is limited by systematic uncertainties related to aquifer composition and lithology, and the extent of water-rock interaction. In principle, radiogenic Ar-40 in groundwater acquired from decay of 40K in aquifer minerals should be insensitive to some processes that impact C-14 and He-4 and thus represent a useful, complementary age tracer. In practice, however, detection of significant radiogenic Ar-40 signals in groundwater has been limited to a small number of studies of extremely old groundwater (>100 ka). Here we present the first high-precision (<1 parts per thousand) measurements of triple Ar isotopes (Ar-40, Ar-38, Ar-36) in groundwater. We introduce a model that distinguishes radiogenic Ar-40 from atmospheric Ar-40 by using the non-radiogenic Ar isotopes (Ar-36, Ar-38) to correct for mass-dependent fractionation. Using this model, we investigate variability in radiogenic Ar-40 excess (Delta Ar-40) across 58 groundwater samples collected from 36 wells throughout California (USA). We find that Delta Ar-40 ranges from similar to 0 parts per thousand (the expected minimum value) to +4.2 parts per thousand across three study areas near Fresno, San Diego, and the western Mojave Desert. Based on measurements from a network of 23 scientific monitoring wells in San Diego, we find evidence for a strong dependence of Delta Ar-40 on aquifer lithology. We suggest that Delta Ar-40 is fundamentally controlled by the weathering of old K-bearing minerals and thus reflects both the degree of groundwater-rock interaction, which is related to groundwater age, and the integrated flow through different geological formations. Future studies of Late Pleistocene groundwater may benefit from high-precision triple Ar isotope measurements as a new tool to better interpret C-14- and He-4-based constraints on groundwater age and flow.
英文关键词	Noble gas Groundwater Isotope geochemistry Groundwater dating
类型	Article
语种	英语
开放获取类型	Green Published
收录类别	SCI-E
WOS记录号	WOS:000702309700010
WOS关键词	GREAT ARTESIAN BASIN ; NOBLE-GASES ; MOLECULAR-DIFFUSION ; MOJAVE DESERT ; CALIFORNIA ; FRACTIONATION ; WATER ; CRUSTAL ; HELIUM ; EOCENE
WOS类目	Geochemistry & Geophysics
WOS研究方向	Geochemistry & Geophysics
来源机构	United States Geological Survey
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/362844
作者单位	[Seltzer, Alan M.; Krantz, John A.; Bekaert, David V.; Barry, Peter H.] Woods Hole Oceanog Inst, Marine Chem & Geochem Dept, Woods Hole, MA 02543 USA; [Ng, Jessica; Kulongoski, Justin T.; Severinghaus, Jeffrey P.] Scripps Inst Oceanog, Geosci Res Div, La Jolla, CA USA; [Danskin, Wesley R.; Kulongoski, Justin T.] US Geol Survey, Calif Water Sci Ctr, San Diego, CA USA; [Kimbrough, David L.] San Diego State Univ, Geol Sci, San Diego, CA 92182 USA
推荐引用方式 GB/T 7714	Seltzer, Alan M.,Krantz, John A.,Ng, Jessica,et al. The triple argon isotope composition of groundwater on ten-thousand-year timescales[J]. United States Geological Survey,2021,583.
APA	Seltzer, Alan M..,Krantz, John A..,Ng, Jessica.,Danskin, Wesley R..,Bekaert, David V..,...&Severinghaus, Jeffrey P..(2021).The triple argon isotope composition of groundwater on ten-thousand-year timescales.CHEMICAL GEOLOGY,583.
MLA	Seltzer, Alan M.,et al."The triple argon isotope composition of groundwater on ten-thousand-year timescales".CHEMICAL GEOLOGY 583(2021).