@article {2996,
	title = {Over a third of groundwater in USA public-supply aquifers is Anthropocene-age and susceptible to surface contamination},
	journal = {Communications Earth \& Environment},
	volume = {3},
	year = {2022},
	month = {07/2022},
	pages = {1 - 9},
	abstract = {The distribution of groundwater age is useful for evaluating the susceptibility and sustainability of groundwater resources. Here, we compute the aquifer-scale cumulative distribution function to characterize the age distribution for 21 Principal Aquifers that account for ~80\% of public-supply pumping in the United States. The aquifer-scale cumulative distribution function for each Principal Aquifer was derived from an ensemble of modeled age distributions (~60 samples per aquifer) based on multiple tracers: tritium, tritiogenic helium-3, sulfur hexafluoride, chlorofluorocarbons, carbon-14, and radiogenic helium-4. Nationally, the groundwater is 38\% Anthropocene (since 1953), 34\% Holocene (75 {\textendash} 11,800 years ago), and 28\% Pleistocene (>11,800 years ago). The Anthropocene fraction ranges from <5 to 100\%, indicating a wide range in susceptibility to land-surface contamination. The Pleistocene fraction of groundwater exceeds 50\% in 7 eastern aquifers that are predominately confined. The Holocene fraction of groundwater exceeds 50\% in 5 western aquifers that are predominately unconfined. The sustainability of pumping from these Principal Aquifers depends on rates of recharge and release of groundwater stored in fine-grained layers.},
	keywords = {Environmental impact, hydrology, Sustainability},
	isbn = {2662-4435},
	doi = {10.1038/s43247-022-00473-y},
	url = {https://www.nature.com/articles/s43247-022-00473-y},
	author = {Jurgens, Bryant C. and Faulkner, Kirsten and McMahon, Peter B. and Hunt, Andrew G. and Casile, Gerolamo and Young, Megan B. and Belitz, Kenneth}
}
@article {2703,
	title = {Comparing and improving methods for reconstructing peatland water-table depth from testate amoebae},
	journal = {The Holocene},
	volume = {29},
	year = {2019},
	month = {Jan-08-2020},
	pages = {1350 - 1361},
	abstract = {Proxies that use changes in the composition of ecological communities to reconstruct temporal changes in an environmental covariate are commonly used in paleoclimatology and paleolimnology. Existing methods, such as weighted averaging and modern analog technique, relate compositional data to the covariate in very simple ways, and different methods are seldom compared systematically. We present a new Bayesian model that better represents the underlying data and the complexity in the relationships between species{\textquoteright} abundances and a paleoenvironmental covariate. Using testate amoeba{\textendash}based reconstructions of water-table depth as a test case, we systematically compare new and existing models in a cross-validation experiment on a large training dataset from North America. We then apply the different models to a new 7500-year record of testate amoeba assemblages from Caribou Bog in Maine and compare the resulting water-table depth reconstructions. We find that Bayesian models represent an improvement over existing methods in three key ways: more complete use of the underlying compositional data, full and meaningful treatment of uncertainty, and clear paths toward methodological improvements. Furthermore, we highlight how developing and systematically comparing methods lead to an improved understanding of the proxy system. This paper focuses on testate amoebae and water-table depth, but the framework and ideas are widely applicable to other proxies based on compositional data.},
	keywords = {Bayesian statistics, compositional data, Holocene, hydrology, North America, Northeast United States, Paleoclimate, peatlands, statistical methods, testate amoebae},
	issn = {0959-6836},
	doi = {10.1177/0959683619846969},
	url = {https://journals.sagepub.com/doi/10.1177/0959683619846969},
	author = {Nolan, Connor and Tipton, John and Booth, Robert K and Hooten, Mevin B and Jackson, Stephen T}
}
