16 research outputs found

    Reservoir Greenhouse Gas Fluxes and Potential Predictor Variables

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    This data file contains reservoir greenhouse gas emission estimates as well as categorical and continuous data for tested predictors of these fluxes. There is one row reserved for each reservoir included in the study. The associated references for this data are included in a second spreadsheet tab

    Percent change in nitrate export in response to stream burial simulation scenarios.

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    <p>The simulation scenarios involve an even distribution of burial across the watershed with incremental increases of 5% and include: 1) Allowing both uptake rate constants and water velocities to change in response to burial (Combined response); 2) Allowing water velocity to change following burial, but holding uptake rate constants at open reach values; and 3) Allowing uptake rate constants to change following burial, but holding water velocities at open reach values.</p

    Stream burial is an extreme, but ubiquitous, consequence of urbanization in stream ecosystems.

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    <p>The buried stream channels in the cited studies were constructed from various materials including (a) a cement-lined corrugated metal pipe in Baltimore, Maryland (USA), (b) a concrete tunnel in Cincinnati, Ohio (USA), and (c) a corrugated metal pipe in Cincinnati.</p

    Biotic variable summary statistics and ANOVA results for Group*Period interaction.

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    1<p>Lambda is value for the exponential transformation.</p>2<p>**<i>P</i><0.01, *<i>P</i><0.05.</p>3<p>PIBI is the Periphyton Index of Biotic Integrity <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0085011#pone.0085011-Hill1" target="_blank">[45]</a>.</p>4<p>Macroinvertebrate variables were calculated separately for multi-habitat net samples (based on abundance data) and bucket samples in riffle habitats (represented as abundance and biomass).</p>5<p>EPT represents taxa in the orders Ephemeroptera, Plecoptera, and Trichoptera (considered sensitive to disturbance).</p

    Results of simulation scenarios involving an even distribution of burial across the watershed with incremental increases of 5%.

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    <p>The primary y-axis and solid line represent the average volumetric NO<sub>3</sub><sup>-</sup> uptake rate among in the open reaches. The secondary y-axis and dashed line represent total NO<sub>3</sub><sup>-</sup> uptake in the open reaches.</p

    High Methane Emissions from a Midlatitude Reservoir Draining an Agricultural Watershed

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    Reservoirs are a globally significant source of methane (CH<sub>4</sub>), although most measurements have been made in tropical and boreal systems draining undeveloped watersheds. To assess the magnitude of CH<sub>4</sub> emissions from reservoirs in midlatitude agricultural regions, we measured CH<sub>4</sub> and carbon dioxide (CO<sub>2</sub>) emission rates from William H. Harsha Lake (Ohio, U.S.A.), an agricultural impacted reservoir, over a 13 month period. The reservoir was a strong source of CH<sub>4</sub> throughout the year, emitting on average 176 ± 36 mg C m<sup>–2</sup> d<sup>–1</sup>, the highest reservoir CH<sub>4</sub> emissions profile documented in the United States to date. Contrary to our initial hypothesis, the largest CH<sub>4</sub> emissions were during summer stratified conditions, not during fall turnover. The river–reservoir transition zone emitted CH<sub>4</sub> at rates an order of magnitude higher than the rest of the reservoir, and total carbon emissions (i.e., CH<sub>4</sub> + CO<sub>2</sub>) were also greater at the transition zone, indicating that the river delta supported greater carbon mineralization rates than elsewhere. Midlatitude agricultural impacted reservoirs may be a larger source of CH<sub>4</sub> to the atmosphere than currently recognized, particularly if river deltas are consistent CH<sub>4</sub> hot spots. We estimate that CH<sub>4</sub> emissions from agricultural reservoirs could be a significant component of anthropogenic CH<sub>4</sub> emissions in the U.S.A

    Box and whisker plots of nitrate uptake velocity (Ê‹<sub>f</sub>) in the buried and open reaches in Cincinnati, Ohio and Baltimore, Maryland, as reported in Beaulieu et al. [20] and Pennino et al. [21].

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    <p>Literature data were derived from a recent survey of 72 streams spanning several biomes and land-use conditions [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132256#pone.0132256.ref016" target="_blank">16</a>]. Plots display 10<sup>th</sup>, 25<sup>th</sup>, 50<sup>th</sup>, 75<sup>th</sup>, and 90<sup>th</sup> percentiles and individual data points outside the 10<sup>th</sup> and 90<sup>th</sup> percentiles. Nitrate uptake velocity was 13 times greater in open than buried reaches (p<0.001, paired <i>t</i>-test).</p

    Physical and chemical variable summary statistics and ANOVA results for Group*Period interaction.

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    <p><sup>1</sup> Lambda is value for the exponential transformation.</p><p><sup>2</sup>***<i>P</i><0.001, *<i>P</i><0.05.</p>3<p>Habitat variables (including some water quality variables) were sampled five times per year during biotic sampling events.</p>4<p>HHEI score from Ohio Environmental Protection Agency Primary Headwater Habitat Evaluation Index <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0085011#pone.0085011-Ohio1" target="_blank">[40]</a>.</p>5<p>QHEI score from Rapid Bioassessment Protocols Quantitative Habitat Assessment for high gradient streams, and filamentous algae score (range 0–4) is from RBP benthic macroinvertebrate field sheet <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0085011#pone.0085011-Barbour1" target="_blank">[39]</a>.</p>6<p>Water quality variables were sampled monthly during baseflow conditions.</p

    ANOVA results for ordination axes.

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    1<p>See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0085011#pone-0085011-t002" target="_blank">Table 2</a> for variable descriptions.</p>2<p>***<i>P</i><0.001, **<i>P</i><0.01, * <i>P</i><0.05. – indicates effect not tested in combined axis model.</p>3<p>Macroinvertebrate abundance and biomass were based on bucket samples in riffle habitats.</p
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