Andrew H Manning

Andrew H Manning
United States Geological Survey | USGS · Geology, Geophysics and Geochemistry Science Center

Ph.D.

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50
Publications
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1,688
Citations

Publications

Publications (50)
Article
Environmental tracers are useful for determining groundwater age and recharge source, yet their application in studies of geogenic Cr(VI) in groundwater has been limited. Environmental tracer data from 166 wells located in the Sacramento Valley, northern California, were interpreted and compared to Cr concentrations to determine the origin and age...
Article
Recent studies suggest that climate change is causing rising solute concentrations in mountain lakes and streams. These changes may be more pronounced in mineralized watersheds due to the sensitivity of sulfide weathering to changes in subsurface oxygen transport. Specific causal mechanisms linking climate change and accelerated weathering rates ha...
Article
a b s t r a c t We compile a unique 13-year record of groundwater age for 11 springs in Sagehen basin, a watershed in the Sierra Nevada Mountains of California, USA. Chlorofluorocarbon (CFC), sulfur hexafluoride (SF 6), and tritium (3 H) data collected in prior studies from 1997 to 2003 are re-interpreted and combined with new data collected in 200...
Article
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The depth of active groundwater circulation is a fundamental control on stream flows and chemistry in mountain watersheds, yet it remains challenging to characterize and is rarely well constrained. We collected hydraulic conductivity, hydraulic head, temperature, chemical, noble gas, and ³H/³He groundwater age data from discrete levels in two boreh...
Article
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Groundwater chemistry has been predominantly used in geochemical exploration studies to identify mineralized targets concealed under transported cover in areas with gentle topography. Another potentially valuable application that has received little attention is using groundwater chemistry to identify deposits concealed within mountain ridges. A nu...
Article
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From 1997 to the present, the U.S. Geological Survey and other agencies have been collecting water samples for chemical analyses on Mount Emmons in central Colorado, USA. The geology of Mount Emmons is dominated by Upper Cretaceous to Paleogene sediments of marine to continental origin, with felsic intrusive rocks interrupting the sedimentary block...
Article
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Sedimentary exhalative (sedex) ore deposits are the world's largest Zn-Pb deposits. While the geologic processes that formed these deposits are generally well understood, the fundamental hydrologic processes that drove these massive hydrothermal systems remain an area of debate. We use numerical modeling to test an emerging hypothesis, supported by...
Conference Paper
Full-text available
Nitrate contamination in groundwater from over-application of fertilizers and wastewater sources is a significant and growing threat to water quality in major aquifers around the world. Nitrate concentrations in groundwater underlying the agriculturally intensive Arborea plain in Sardinia (Italy) commonly exceed the World Health Orga-nization's thr...
Article
Regional geochemical databases for the northern Midwest USA are being compiled to examine the various geogenic and anthropogenic factors that control the chemistry of groundwater. At the regional scale, variations are seen that are attributable to agricultural and urban effects, or to geologic factors. Examples of the former include enrichments of...
Article
Determining groundwater discharge to streams using dissolved gases is known to be useful over a wide range of streamflow rates but the suitability of dissolved gas methods to determine discharge rates in high gradient mountain streams has not been sufficiently tested, even though headwater streams are critical as ecological habitats and water resou...
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The He, Ne, and Ar isotopic composition of fluid inclusions in ore and gangue minerals were analyzed to determine the source of volatiles in the high-grade Goldfield and Tonopah epithermal Au-Ag deposits in southwestern Nevada, USA. Ar and Ne are mainly atmospheric, whereas He has only a minor atmospheric component. Corrected ³He/⁴He ratios (with a...
Article
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Existing studies on the impacts of climate change on groundwater recharge are either global or basin/location-specific. The global studies lack the specificity to inform decision making, while the local studies do little to clarify potential changes over large regions (major river basins, states, or groups of states), a scale often important in the...
Article
Environmental tracers provide information on groundwater age, recharge conditions, and flow processes which can be helpful for evaluating groundwater sustainability and vulnerability. Dissolved noble gas data have proven particularly useful in mountainous terrain because they can be used to determine recharge elevation. However, tracer-derived rech...
Article
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Montezuma Well is a unique natural spring located in a sinkhole surrounded by travertine. Montezuma Well is managed by the National Park Service, and groundwater development in the area is a potential threat to the water source for Montezuma Well. This research was undertaken to better understand the sources of groundwater to Montezuma Well. Stront...
Article
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A unique 30-year streamwater chemistry data set from a mineralized alpine watershed with naturally acidic, metal-rich water displays dissolved concentrations of Zn and other metals of ecological concern increasing by 100-400% (400-2000 μg/L) during low-flow months, when metal concentrations are highest. SO(4) and other major ions show similar incre...
Conference Paper
Full-text available
A water, energy, and biogeochemical model (WEBMOD) was constructed to simulate hydrology and pyrite oxidation for the period October 1992 through September 1997. The hydrologic model simulates processes in Loch Vale, a 6.6-km² granitic watershed that drains the east side of the Continental Divide. Parameters describing pyrite oxidation were derived...
Article
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Water tables at regional to continental scales can be classified into two distinct types: recharge-controlled water tables that are largely disconnected from topography and topography-controlled water tables that are closely tied to topography. We use geomatic synthesis of hydrologic, geologic and topographic data sets to quantify and map water-tab...
Article
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Noble gas recharge temperatures (NGTs) and radiocarbon ages were determined for 43 groundwater samples collected in the eastern Espa ola Basin, New Mexico (USA), to identify mountain-block recharge in waters <10 thousand years (ka) old and to evaluate possible changes in mountain-block recharge over the past similar to 35ka. For Holocene samples fr...
Article
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Permeability, the ease of fluid flow through porous rocks and soils, is a fundamental but often poorly quantified component in the analysis of regional-scale water fluxes. Permeability is difficult to quantify because it varies over more than 13 orders of magnitude and is heterogeneous and dependent on flow direction. Indeed, at the regional scale,...
Technical Report
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Geophysical data were collected at the Standard Mine in Elk Basin near Crested Butte, Colorado, to help improve the U.S. Environmental Protection Agency’s understanding of the hydrogeologic controls in the basin and how they affect surface and groundwater interactions with nearby mine workings. These data are discussed in the context of geologic ob...
Article
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An understanding of the natural production of low-pH and metal-rich ground and surface water (acid-rock drainage, or ARD) in mineralized watersheds is important for establishing pre-mining conditions in mined locations and for evaluating the potential environmental impacts of future mining in unmined locations. The significance of hydrothermal alte...
Article
Geophysical and geologic data were collected at the Standard Mine in Elk Basin near Crested Butte, CO, to improve our understanding of the hydrogeologic controls in the basin and how they influence surface and groundwater interactions with nearby mine workings. The Tertiary Ohio Creek and Wasatch formations are the bedrock geologic units; both are...
Conference Paper
The Development of Mineral Environmental Assessment Methodologies Project (MEAP) is a new project within the U.S. Geological Survey’s Mineral Resources Program. One objective of the MEAP is to predict potential environmental impacts at a watershed scale, with associated uncertainty, from future mining activities. One initial task is to determine th...
Article
The solubility of noble gases in water is temperature dependent. Noble gas concentrations in ground water can therefore be used to determine the temperature at the water table at the recharge location (recharge temperature). The Pajarito Plateau in Northern New Mexico is an example of a hydrogeologic setting where noble gas recharge temperatures pr...
Article
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This study uses numerical simulations to define the salient controls on regional groundwater flow in 3-D mountainous terrain by systematically varying topographic and hydrogeologic variables. Topography for idealized multiple-basin mountainous terrain is derived from geomatic data and literature values. Water table elevation, controlled by the rati...
Article
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Water-table elevation measurements and aquifer parameter estimates are rare in alpine settings because few wells exist in these environments. Alpine groundwater systems may be a primary source of recharge to regional groundwater flow systems. Handcart Gulch is an alpine watershed in Colorado, USA comprised of highly fractured Proterozoic metamorphi...
Article
Understanding how ground water transports metals and acid to mountain streams is critical in order to effectively manage mountain watersheds affected by acid-rock and acid-mine drainage. The transport of dissolved constituents in ground water is best represented by a coupled numerical ground-water How and solute-transport model. Building such a num...
Article
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Handcart Gulch is an alpine watershed along the Continental Divide. It contains an unmined mineral occurrence composed primarily of pyrite with trace metals including copper and molybdenum. Although the geology of Handcart Gulch is typical of many hydrothermal mineral deposits in the intermountain West, the area is unique because of a set of deep a...
Article
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Geochemical studies show a variety of different types of water in Big Bend National Park. Rainfall recharges ground water aquifers that supply wells and springs that constitute significant drinking water supplies at The Basin, the Headquarters area, Rio Grande Village, and the Castolon area. Panther Junction, K-Bar, and oak Spring produce water tha...
Article
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1] Bedrock groundwater in alpine watersheds is poorly understood, mainly because of a scarcity of wells in alpine settings. Groundwater noble gas, age, and temperature data were collected from springs and wells with depths of 3–342 m in Handcart Gulch, an alpine watershed in Colorado. Temperature profiles indicate active groundwater circulation to...
Article
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1] The subsurface transfer of water from a mountain block to an adjacent basin (mountain block recharge (MBR)) is a commonly invoked mechanism of recharge to intermountain basins. However, MBR estimates are highly uncertain. We present an approach to characterize bulk fluid circulation in a mountain block and thus MBR that utilizes environmental tr...
Article
Regulatory agencies are becoming increasingly interested in using young-ground water dating techniques, such as the 3H/3He method, in assessing the susceptibility of public supply wells (PSWs) to contamination. However, recent studies emphasize that ground water samples of mixed age may be the norm, particularly from long-screened PSWs, and tracer-...
Article
Here we present information from an innovative suite of stable, radiogenic, and cosmogenic isotopes to better understand groundwater flowpaths and groundwater-surface water interactions in an applied acid mine drainage system. Stable water isotopes, tritium, helium-tritium, sulfur-35, and uranium 234/238 ratios were analyzed from precipitation, gro...
Article
Measurements of dissolved gases have numerous applications in ground water hydrology, and it is now possible to measure the total dissolved gas pressure in situ using a probe. Dissolved gas pressure is measured by submerging a headspace volume with a gas-permeable membrane, allowing dissolved gases in the water to equilibrate with gases in the head...
Article
Mountain-front recharge is a major component of recharge to inter-mountain basin-fill aquifers. The two components of mountain-front recharge are (1) subsurface inflow from the mountain block (subsurface inflow), and (2) infiltration from perennial and ephemeral streams near the mountain front (stream seepage). The magnitude of subsurface inflow is...
Article
Much of the recent debate over low-angle normal faults exposed in metamorphic core complexes has centered on the rolling hinge model. The model predicts tilting of seismogenic high-angle normal faults to lower dips by footwall deformation in response to isostatic forces caused by footwall exhumation. This shallow brittle deformation should visibly...
Article
Slickensided fractures occur in 52% of the 235 Mesozoic dikes examined in Vermont, New Hampshire, and southern Maine. About 80% are tectonically reactivated cooling joints; about 20% are true faults. Stress configurations were derived from the fractures by using the Gephart stress inversion programs. The data provide clear evidence for east-northea...

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