pH and Acid Anion Time Trends in Different Elevation Ranges in the Great Smoky Mountains National Park

Robinson, Robert J.; Barnett, Thomas W.; Harwell, Glenn R.; Moore, Stephen E.; Kulp, Matt A.; Schwartz, John S.

doi:10.1061/(asce)0733-9372(2008)134:9(800)

Cited by 17 publications

(9 citation statements)

References 34 publications

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“…The dominant vegetation types in the GRSM include montane oak‐hickory (31%), high‐elevation hardwood (17%), yellow pine species (16%), cove hardwood (12%) and spruce‐fir forest (8%) (Jenkins, ; Whittaker, ). Park watersheds are sensitive to acidic deposition due to high‐elevation topographic features coupled with highly weathered, unglaciated, base‐poor soils, shallow hydrological flowpaths and mature forests (Cai, Johnson, Schwartz, Moore, & Kulp, ; Johnson & Lindberg, ; Neff, Schwartz, Moore, & Kulp, ; Robinson et al., ). Atmospheric sulphur and nitrogen depositions have resulted in acidification of the soil and the stream water in GRSM (Cook et al., ; Deyton et al., ; Nodvin, Van Miegroet, Lindberg, Nicholas, & Johnson, ).…”

Section: Methodsmentioning

confidence: 99%

Native brook trout and invasive rainbow trout respond differently to seasonal weather variation: Spawning timing matters

et al. 2017

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Salmonids have been introduced globally, and native and invasive salmonids co‐exist in many regions. However, their responses to seasonal weather variation and global climate change are poorly known. The aim of this study was to compare effects of inter‐annual variation in seasonal weather patterns on native brook trout (BKT) (Salvelinus fontinalis) versus invasive rainbow trout (RBT) (Oncorhynchus mykiss) abundance using summer electrofishing data (May through September) spanning 28 years in the Great Smoky Mountains National Park, U.S.A. (c. 200 stream sites per species). In particular, we tested if different spawning timing between BKT (autumn) and RBT (late winter) would result in heterogeneous population responses to high seasonal precipitation, which would negatively affect early life stages with impaired swimming ability. As predicted, young‐of‐the‐year (YOY) abundance of autumn‐spawning BKT was most strongly impacted by total precipitation between February and March, and RBT YOY abundance was most strongly impacted by peak precipitation between April and May. Despite the presence of these different key seasonal drivers, inter‐annual variation in YOY density of these two species was positively correlated because precipitation in April and May also impacted the abundance of BKT YOY. Adult abundance was less responsive to weather variation than YOY abundance, and was most strongly correlated with YOY abundance in the previous year, indicating the importance of flow‐driven population control influences on early life stages affecting population sizes into subsequent years. Adult BKT densities were not affected by any weather covariate, whereas adult RBT densities were correlated with four weather covariates in competing models. As a result, there was no correlation in the inter‐annual variation in adult density in these two species. The differing responses of BKT and RBT to long‐term seasonal weather patterns suggest that they will likely respond differently to global climate change. In particular, winter precipitation will likely be the key environmental driver of differences in their population responses.

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Section: Methodsmentioning

confidence: 99%

Native brook trout and invasive rainbow trout respond differently to seasonal weather variation: Spawning timing matters

et al. 2017

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“…Because trends and seasonal patterns in stream acidification response differ regionally, it is important to document responses among locations where longterm data exists. In the GRSM, Robinson et al (2008) investigated trends with stream baseflow chemistry among elevation ranges finding sulfate concentration and pH declines between 1993 and 2002 in the lower elevation streams (<1,060 m), but not at the higher elevations. No trends were observed for nitrate and acid neutralizing capacity (ANC) from that park-wide dataset.…”

Section: Introductionmentioning

confidence: 99%

Long-Term Annual and Seasonal Patterns of Acidic Deposition and Stream Water Quality in a Great Smoky Mountains High-Elevation Watershed

Cai

Schwartz

Robinson

et al. 2011

Water Air Soil Pollut

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The recovery potential of stream acidification from years of acidic deposition is dependent on biogeochemical processes and varies among different acidsensitive regions. Studies that investigate long-term trends and seasonal variability of stream chemistry in the context of atmospheric deposition and watershed setting provide crucial assessments on governing biogeochemical processes. In this study, water chemistries were investigated in Noland Divide watershed (NDW), a high-elevation watershed in the Great Smoky Mountains National Park (GRSM) of the southern Appalachian region. Monitoring data from 1991 to 2007 for deposition and stream water chemistries were statistically analyzed for long-term trends and seasonal patterns by using Seasonal Kendall Tau tests. Precipitation declined over this study period, where throughfall (TF) declined significantly by 5.76 cm year −1 . Precipitation patterns play a key role in the fate and transport of acid pollutants. On a monthly volume-weighted basis, pH of TF and wet deposition, and stream water did not significantly change over time remaining around 4.3, 4.7, and 5.8, respectively. Per NDW area, TF SO 4 2-flux declined 356.16 eq year −1 and SO 4 2-concentrations did not change significantly over time. Stream SO 4 2-remained about 30 μeq L −1 exhibiting no long-term trends or seasonal patterns. SO 4 2-retention was generally greater during drier months. TF monthly volume-weighted NH 4 + and NO 3 -concentrations significantly increased by 0.80 μeq L −1 year −1 and 1.24 μeq L −1 year −1 , respectively. TF NH 4 + fluxes increased by 95.76 eq year −1 . Most of NH 4 + was retained in the watershed, and NO 3 -retention was much lower than NH 4 + . Stream monthly volumeweighted NO 3 -concentrations and fluxes significantly declined by 0.56 μeq L −1 year −1 and 139.56 eq year −1 , respectively. Overall, in NDW, inorganic nitrogen was exported before 1999 and retained since then, presumably from forest regrowth after Frazer fir die-off in the 1970s from balsam wooly adelgid infestation. Stream export of NO 3 -was greater during winter than summer months. During the period from 1999 to 2007, stream base cations did not exhibit significant changes, apparently regulated by soil supply. Statistical models predicting stream pH, ANC, SO 4 2-, and NO 3 -concentrations were largely correlated with stream discharge and number of dry days between precipitation events and SO 4 2-deposition. Dependent on precipitation, governing biogeochemical processes in NDW appear to be SO 4 2-adsorption, nitrification, and NO 3 -forest uptake. This study provided essential information to aid the GRSM management for developing predictive models of the future water quality and potential impacts from climate change.

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“…Surface water of high elevation watersheds in the GRSM and elsewhere in the eastern USA have been shown to be especially sensitive to acidic inputs due to a limited ability to neutralize acidic deposition, as evidenced by low stream pH and acid neutralizing capacity (ANC; Johnson and Lindberg 1992;Robinson et al 2008;Silsbee and Larson 1982). The Noland Divide Watershed (NDW), a high-elevation watershed in the GRSM, has historically received high rates of ammonium, nitrate, and sulfate via precipitation and has shown symptoms of acidity sensitivity.…”

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Soil Acid-Base Chemistry of a High-Elevation Forest Watershed in the Great Smoky Mountains National Park: Influence of Acidic Deposition

Cai

Johnson

Schwartz

et al. 2011

Water Air Soil Pollut

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Understanding the acid-base chemistry of soil and the soil processes related to the release or retention of sulfate and nitrate is important in order to predict watershed recovery from long-term acid deposition. Soils were sampled from the Noland Divide Watershed (NDW), a small, high-elevation watershed in the Great Smoky Mountains National Park receiving high rates of acid deposition over several decades. Soil samples were measured for chemical properties related to acidification and used to conduct sulfate adsorption and nitrogen (N) incubation experiments. Shallow soil was higher in acidic and basic ions than deeper soils, and the mean effective cation exchange capacity was 8.07, 5.06, and 3.57 cmol c kg −1 in the A, Bw, and Cb horizons, respectively. In all three soil horizons, the base saturation was equal to or below 7% and the ratio of Ca/Al was below 0.01, indicating that the NDW is very sensitive to acid deposition. Based on results from sulfate adsorption isotherms, the NDW has not reached its maximum sulfate adsorption saturation and is likely able to retain further additions of sulfate. Desorption of sulfate from NDW soils is expected if sulfate concentrations in soil solution drop below 50 μeq L −1 but is highly dependent on soil pH and organic carbon content. Total soil organic N was 500 times greater than inorganic N in the A soil horizon, and net N mineralization and nitrification remained constant during a 28-day incubation indicating a large reservoir of N substrate for soil microbes. Nitrogen experiment results suggest that nitrate export from the watershed is largely controlled by biological processes rather than by nitrate deposition flux. Soil data collected in this study contributes to our understanding of biogeochemical processes affecting the response of acid-impacted ecosystems such as the NDW to future changes in atmospheric deposition.

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pH and Acid Anion Time Trends in Different Elevation Ranges in the Great Smoky Mountains National Park

Cited by 17 publications

References 34 publications

Native brook trout and invasive rainbow trout respond differently to seasonal weather variation: Spawning timing matters

Native brook trout and invasive rainbow trout respond differently to seasonal weather variation: Spawning timing matters

Long-Term Annual and Seasonal Patterns of Acidic Deposition and Stream Water Quality in a Great Smoky Mountains High-Elevation Watershed

Soil Acid-Base Chemistry of a High-Elevation Forest Watershed in the Great Smoky Mountains National Park: Influence of Acidic Deposition

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