Oxidative dissolution under the channel leads geomorphological evolution at the Shale Hills catchment

Sullivan, Pamela L.; Hynek, Scott A.; Gu, Xiaoxiong; Singha, Kamini; White, Timothy S.; West, Nicole; Kim, Hyojin; Clarke, B. A.; Kirby, Eric; Duffy, Christopher; Brantley, Susan L.

doi:10.2475/10.2016.02

Cited by 59 publications

(118 citation statements)

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“…However, further investigation is needed to understand the timescales of water and solute flux in Garner Run. This requires quantitative analysis of vegetation distribution, groundwater residence time, soil characteristics, fracture networks, and aspect dependence, which were important drivers of water flux at Shale Hills [ Lin , ; West et al ., ; Herndon et al ., ; Sullivan et al ., ]. Based upon the data set presented here, we propose that the difference in the routing and residence time of subsurface flow paths through solute‐generating zones, as governed by bedrock lithology, influences CQ trends in headwater streams.…”

Section: Discussionmentioning

confidence: 99%

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Hyporheic zone influences on concentration‐discharge relationships in a headwater sandstone stream

Hoagland

Russo

et al. 2017

Water Resources Research

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Complex subsurface flow dynamics impact the storage, routing, and transport of water and solutes to streams in headwater catchments. Many of these hydrogeologic processes are indirectly reflected in observations of stream chemistry responses to rain events, also known as concentration-discharge (CQ) relations. Identifying the relative importance of subsurface flows to stream CQ relationships is often challenging in headwater environments due to spatial and temporal variability. Therefore, this study combines a diverse set of methods, including tracer injection tests, cation exchange experiments, geochemical analyses, and numerical modeling, to map groundwater-surface water interactions along a first-order, sandstone stream (Garner Run) in the Appalachian Mountains of central Pennsylvania. The primary flow paths to the stream include preferential flow through the unsaturated zone (''interflow''), flow discharging from a spring, and groundwater discharge. Garner Run stream inherits geochemical signatures from geochemical reactions occurring along each of these flow paths. In addition to end-member mixing effects on CQ, we find that the exchange of solutes, nutrients, and water between the hyporheic zone and the main stream channel is a relevant control on the chemistry of Garner Run. CQ relationships for Garner Run were compared to prior results from a nearby headwater catchment overlying shale bedrock (Shale Hills). At the sandstone site, solutes associated with organo-mineral associations in the hyporheic zone influence CQ, while CQ trends in the shale catchment are affected by preferential flow through hillslope swales. The difference in CQ trends document how the lithology and catchment hydrology control CQ relationships. Plain Language Summary Stream chemistry serves as a fingerprint for the processes that occur in the critical zone, which extends from unweathered bedrock to the top of the tree canopy. The critical zone thus includes all resources critical to life. This paper evaluates chemical and physical processes in the critical zone, specifically in soils, streams, and groundwater. Our work suggests the important influence of groundwater-surface water interactions on mountain streams with an emphasis on the transport of water and solutes through the streambed. By comparing these transport processes on sandstone and shale, we hypothesize that the type of rock underlying a watershed can influence the relative importance of groundwater-surface water interactions on stream chemistry.

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Section: Discussionmentioning

confidence: 99%

“… All stream chemistry from SH weir site [ Sullivan et al ., ], except pH and DOC [ Herndon et al ., ].…”

Section: Methodsmentioning

confidence: 99%

Hyporheic zone influences on concentration‐discharge relationships in a headwater sandstone stream

Hoagland

Russo

et al. 2017

Water Resources Research

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“…In other words, observatories induce scientists from different disciplines to make measurements using different disciplinary approaches at the same location instead of making them at disparate sites, driving cross-disciplinary understanding in describing CZ function (Hynek et al, 2017;Sullivan et al, 2016;Yan et al, 2017;Chen et al, 2017, in press). At first, much of the synthesis crossed only two disciplines at a time: for example, several papers emphasized how geomorphological concepts related to erosion must be incorporated to understand chemical weathering, and vice versa (Rempe and Dietrich, 2014;Riebe et al, 2016).…”

Section: The Nine Emergent Roles Of Czosmentioning

confidence: 99%

“…First, we have observed that differences in natural and anthropogenic inputs at Earth's surface translate into differences in water, regolith structure, minerals, and biotic activity at depth, and we are starting to detect how these deep properties also impact the biota, climate, and CZ services (e.g., Richter and Billings, 2015;Sullivan et al, 2016;Richardson and Kumar, 2017;Chorover et al, 2011).…”

Section: Emergent Network-level Conceptsmentioning

confidence: 99%

Designing a network of critical zone observatories to explore the living skin of the terrestrial Earth

et al. 2017

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Abstract. The critical zone (CZ), the dynamic living skin of the Earth, extends from the top of the vegetative canopy through the soil and down to fresh bedrock and the bottom of the groundwater. All humans live in and depend on the CZ. This zone has three co-evolving surfaces: the top of the vegetative canopy, the ground surface, and a deep subsurface below which Earth's materials are unweathered. The network of nine CZ observatories supported by the US National Science Foundation has made advances in three broad areas of CZ research relating to the co-evolving surfaces. First, monitoring has revealed how natural and anthropogenic inputs at the vegetation canopy and ground surface cause subsurface responses in water, regolith structure, minerals, and biotic activity to considerable depths. This response, in turn, impacts aboveground biota and climate. Second, drilling and geophysical imaging now reveal how the deep subsurface of the CZ varies across landscapes, which in turn influences aboveground ecosystems. Third, several new mechanistic models now provide quantitative predictions of the spatial structure of the subsurface of the CZ.Many countries fund critical zone observatories (CZOs) to measure the fluxes of solutes, water, energy, gases, and sediments in the CZ and some relate these observations to the histories of those fluxes recorded in landforms, biota, soils, sediments, and rocks. Each US observatory has succeeded in (i) synthesizing research across disciplines into convergent approaches; (ii) providing long-term measurements to compare across sites; (iii) testing and developing models; (iv) collecting and measuring baseline data for comparison to catastrophic events; (v) stimulating new process-based hypotheses; (vi) catalyzing development of new techniques and instrumentation; (vii) informing the public about the CZ; (viii) mentoring students and teaching about emerging multidisciplinary CZ science; and (ix) discovering new insights about the CZ. Many of these activities can only be accomplished with observatories. Here we review the CZO enterprise in the United States and identify how such observatoriesPublished by Copernicus Publications on behalf of the European Geosciences Union. 842 S. L. Brantley et al.: Designing a network of critical zone observatories could operate in the future as a network designed to generate critical scientific insights. Specifically, we recognize the need for the network to study network-level questions, expand the environments under investigation, accommodate both hypothesis testing and monitoring, and involve more stakeholders. We propose a driving question for future CZ science and a "hubs-and-campaigns" model to address that question and target the CZ as one unit. Only with such integrative efforts will we learn to steward the life-sustaining critical zone now and into the future.

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“…To first approximation, unsaturated soils on planar slopes are characterized by vertical downward flow. Horizontal flow occurs at the base of pedons—the interface of soil with underlying rock—and sometimes at the interface of the A and B horizons when saturation occurs (Brantley et al, ; Jin et al, ; Lin, ; Sullivan, Hynek, et al, ; Sullivan, Ma, et al, ; Thomas et al, ). In this modeling effort, we focused on the changes in water chemistry versus depth that were dictated by unsaturated flow conditions.…”

Section: Introductionmentioning

confidence: 99%

Exploring the Effect of Aspect to Inform Future Earthcasts of Climate‐Driven Changes in Weathering of Shale

et al. 2019

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Projections of future conditions within the critical zone—earthcasts—can be used to understand the potential effects of changes in climate on processes affecting landscapes. We are developing an approach to earthcast how weathering will change in the future using scenarios of climate change. As a first step here, we use the earthcasting approach to model aspect‐related effects on soil water chemistry and weathering on hillsides in a well‐studied east‐west trending watershed (Shale Hills, Pennsylvania, USA). We completed model simulations of solute chemistry in soil water with and without the effect of aspect for comparison to catchment observations. With aspect included, aqueous weathering fluxes were higher on the sunny side of the catchment. But the effect of aspect on temperature (0.8 °C warmer soil on sunny side) and recharge (100 mm/year larger on shaded side) alone did not explain the magnitude of the observed higher weathering fluxes on the sunny side. Modeled aspect‐related differences in weathering fluxes only approach field observations when we incorporated the measured differences in clay content observed in augered soils on the two hillslopes. We also had to include a biolifting module to accurately describe cation concentrations in soil water versus depth. Biolifting lowered some mineral dissolution rates while accelerating kaolinite precipitation. These short‐duration simulations also highlighted that the inherited differences in particle size on the two sides of the catchment might in themselves be explained by weathering under different microclimates caused by aspect—over longer durations than simulated with our models.

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Oxidative dissolution under the channel leads geomorphological evolution at the Shale Hills catchment

Cited by 59 publications

References 79 publications

Hyporheic zone influences on concentration‐discharge relationships in a headwater sandstone stream

Hyporheic zone influences on concentration‐discharge relationships in a headwater sandstone stream

Designing a network of critical zone observatories to explore the living skin of the terrestrial Earth

Exploring the Effect of Aspect to Inform Future Earthcasts of Climate‐Driven Changes in Weathering of Shale

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