Paleoclimate Signals and Groundwater Age Distributions From 39 Public Water Works in the Netherlands; Insights From Noble Gases and Carbon, Hydrogen and Oxygen Isotope Tracers

Abstract

Worldwide, groundwater is one of the most important sources for fresh water supply. Approximately 70% of the Dutch population relies on groundwater for their drinking water, especially in the southern and eastern parts of the Netherlands where unconsolidated sandy deposits provide the best aquifers. Globally, groundwater resources are under pressure from overexploitation (Aeschbach-Hertig & Gleeson, 2012;Gleeson et al., 2012) and point and diffuse sources of pollution, especially by pesticides and nutrients from intensive use of agricultural lands. (Hansen et al., 2010;Nolan et al., 1997;Visser et al., 2007). The Netherlands is one of the most densely populated countries with an economy that is partly based on its agricultural sector. These two factors lead to high water demands and pressures on the groundwater system. The strong increase of intensive livestock farming in the Netherlands has created an increasing pressure on the groundwater pumped for drinking water supply (Mendizabal & Stuyfzand, 2011, Mendizabal et al., 2012. Although European legislation (EU, 2006) aims at reducing the leaching of agricultural contaminants to groundwater and surface water resources, many well fields for public water supply are still under threat. This resulted in the systematic closure of shallow well fields during the past 3 decades. Blending of water from different aquifers and different locations is often required to satisfy drinking water standards (e.g., Visser et al., 2013). Moreover, new developments put pressure on the available groundwater resources, such as the exponential increase of aquifer thermal energy systems in urbanized areas (Bonte et al., 2011) and the increased demands for irrigation from groundwater due to water scarcity during dry summers in agricultural areas.

Multi‐Tracer Groundwater Dating in Southern Oman Using Bayesian Modeling

“…All wells exhibited age distributions of two clusters with a large gap in between, indicating water below 30 yr and beyond 1,000 yr. While the occurrence of two peaks in the age distribution of groundwater has been found in other studies as well (Broers et al., 2021; McCallum et al., 2017), the extreme age difference observed here seems unusual and may be related to the rather special hydrogeological and climatic conditions of the Salalah Plain.…”

“…If a water mixture cannot be described by analytical models, complex numerical methods can offer a broader range of possibilities (Broers et al., 2021; Cirpka et al., 2007; Troldborg et al., 2008; Visser et al., 2013). Those shape‐free models, also called nonparametric models or age histograms, can help to identify the age contributions from a selected number of bins.…”

Evaluation of Aqueous Gastropod Shells as Groundwater Radiocarbon Proxies Across Species and Sites

“…The 14 C s proxy described in this study can be used to model groundwater transit times rather than direct measurement of 14 C gw . Measurements of 14 C gw are commonly used to estimate aquifer transit times, and many methods have been developed to do this by not only considering the radioactive decay of 14 C along the flowpath, but also corrections including the distiubution of flowpath lengths sampled (e.g., Jurgens et al 2016;Broers et al 2021) and the input of 14 C in pre-recharge atmosphere, DIC from the dissolution of aquifer materials, or soil CO 2 (Fontes and Garnier 1979;Kalin 2000;Clark and Fritz 2013;Clark 2015;Han and Plummer 2016;Cartwright et al 2020;Wang et al 2020 For example, the apparent 14 C transit time at BL-Spring was modelled by Lerback et al 2019) to be on average Holocene recharge. They used the measured 14 C of 8.5 pMC, δ 13 C of -4.5‰, and alkalinity of 226 mg/L as CaCO3 and pH of 7.3, with an initial 14 C of 100 pMC and δ 13 C of -22‰.…”

Reconstruction of the Pleistocene Paleoclimate From Deep Groundwater in Southern Germany From Noble Gas Temperatures Linked With Organic Radiocarbon Dating

“…Several paleoclimate studies from European aquifers show differing groundwater evolution during this time (McIntosh et al., 2012). Some of the studies from aquifer systems located in Belgium (Blaser et al., 2010), England (Andrews & Lee, 1979), and Switzerland (Beyerle et al., 1998) have shown an interruption in continuous groundwater recharge, which occurred during the Late Pleistocene, while other basins show no or no complete cessation of groundwater recharge between 17 and 25 ka (e.g., Broers et al., 2021; Varsányi et al., 2011).…”