干旱区生态环境知识资源中心(Arid): Identifying paleowater in California drinking water wells

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DOI	10.1016/j.quaint.2019.04.008
	Identifying paleowater in California drinking water wells
	de Jong, Menso; Moran, Jean E.; Visser, Ate
通讯作者	Moran, JE
来源期刊	QUATERNARY INTERNATIONAL
ISSN	1040-6182
EISSN	1873-4553
出版年	2020
卷号	547 页码:197-207
英文摘要	Identification of paleowater in aquifers tapped for the public water supply is important both for sound water management, because paleowater is likely to be withdrawn unsustainably in high demand regions in the absence of large scale artificial recharge operations, and for contamination susceptibility assessment, because paleowater is typically isolated from contamination sources. In this study, paleowater, which herein includes pre-Holocene groundwater and also water that recharged well before the onset of significant human alteration of the hydrologic system in California, is identified using three key isotopic indicators of groundwater residence time: tritium (H-3), radiocarbon (C-14), and radiogenic helium-4 (He-4(rad)). We compared results of these three tracers from a unique data set of more than 2000 wells that are predominantly long-screened drinking water production wells. Although considerable uncertainty is associated with calculated apparent ages for individual samples, non-parametric statistical tests indicate that the composite set of isotopic indicators support classification of samples into categories that allow identification of wells most likely to produce paleowater. Approximately 7% of the wells included in the study show strong evidence for producing paleowater, with screens extending greater than 146 m below ground surface, in which 3H activity is less than 1 pCi/L, C-14 activity is less than 40.9 pmC, and He-4(rad) concentration exceeds 7.4 x 10(-8) cm(3)STP/g(water). An additional 22% of wells produce mixed-age water with a component of paleowater, with screens extending greater than 95 m below ground surface, in which H-3 is less than 5 pCi/L, and C-14 activity is less than 95.91 pmC. Wells in desert basins of southeastern California and wells in the southwestern quadrant of the Central Valley are most likely to produce paleowater that is pre-Holocene in age. Very few wells in the northwestern portion of the state, the foothills and Sierra Nevada regions, and coastal basins with intensive artificial recharge activities are categorized as producing paleowater. Climate is the primary control on paleowater occurrence, with arid portions of the state that were wetter during the Pleistocene having the largest number of wells categorized as producing paleowater. Secondarily, paleowater is found at the end of very long flow paths in confined aquifers, e.g., in the center of the Northern Sacramento Valley. In contrast, paleowater may be masked in areas where unconfined or semi-confined conditions allow substantial mixing between modern recharge and paleowater. Modern, artificially recharged water has replaced very old groundwater on a large scale in urban coastal basins.
类型	Article
语种	英语
收录类别	SCI-E
WOS记录号	WOS:000562456200002
WOS关键词	DISSOLVED NOBLE-GASES ; SAN-JOAQUIN VALLEY ; GROUNDWATER ; AQUIFER ; RADIOCARBON ; RECHARGE ; TRITIUM ; HELIUM ; FLOW ; GEOCHEMISTRY
WOS类目	Geography, Physical ; Geosciences, Multidisciplinary
WOS研究方向	Physical Geography ; Geology
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/325806
作者单位	[de Jong, Menso] Univ Calif Santa Barbara, Santa Barbara, CA 93106 USA; [Moran, Jean E.] Calif State Univ East Bay, Hayward, CA 94542 USA; [Visser, Ate] Lawrence Livermore Natl Lab, Lawrence, KS USA
推荐引用方式 GB/T 7714	de Jong, Menso,Moran, Jean E.,Visser, Ate. Identifying paleowater in California drinking water wells[J],2020,547:197-207.
APA	de Jong, Menso,Moran, Jean E.,&Visser, Ate.(2020).Identifying paleowater in California drinking water wells.QUATERNARY INTERNATIONAL,547,197-207.
MLA	de Jong, Menso,et al."Identifying paleowater in California drinking water wells".QUATERNARY INTERNATIONAL 547(2020):197-207.