John S. Schwartz

Temporal Variation and Persistence of Bacteria in Streams

Better understanding of bacterial fate and transport in watersheds is necessary for improved regulatory management of impaired streams. Novel statistical time series analyses of coliform data can be a useful tool for evaluating the dynamics of temporal variation and persistence of bacteria within a watershed. For this study, daily total coliform data for the Little River in East Tennessee from 1 Oct. 2000 to 31 Dec. 2005 were evaluated using novel time series techniques. The objective of this study was to analyze the total coliform concentration data to: (i) evaluate the temporal variation of the total coliform, and (ii) determine whether the total coliform concentration data demonstrated any long-term or short-term persistence. For robust analysis and comparison, both time domain and frequency domain approaches were used for the analysis. In the time domain, an autoregressive moving average approach was used; whereas in the frequency domain, spectral analysis was applied. As expected, the analyses showed that total coliform concentrations were higher in summer months and lower in winter months. However, the more interesting results showed that the total coliform concentration exhibited short-term as well as long-term persistence ranging from about 4 wk to approximately 1 yr, respectively. Comparison of the total coliform data to hydrologic data indicated both runoff and baseflow are responsible for the persistence.

Suspended sediment regimes in contrasting reference-condition freshwater ecosystems: implications for water quality guidelines and management.

Suspended sediment (SS), ranging from nano-scale particles to sand-sized sediments, is one of the most common contributors to water quality impairment globally. However, there is currently little scientific evidence as to what should be regarded as an appropriate SS regime for different freshwater ecosystems. In this article, we compare the SS regimes of ten systematically-selected contrasting reference-condition temperate river ecosystems that were observed through high-resolution monitoring between 2011 and 2013. The results indicate that mean SS concentrations vary spatially, between 3 and 29 mg L(-1). The observed mean SS concentrations were compared to predicted mean SS concentrations based on a model developed by Bilotta et al. (2012). Predictions were in the form of probability of membership to one of the five SS concentration ranges, predicted as a function of a number of the natural environmental characteristics associated with each rivers catchment. This model predicted the correct or next closest SS range for all of the sites. Mean annual SS concentrations varied temporally in each river, by up to three-fold between a relatively dry year (2011-2012) and a relatively wet year (2012-2013). This inter-annual variability could be predicted reasonably well for all the sites except the River Rother, using the model described above, but with modified input data to take into account the mean annual temperature (°C) and total annual precipitation (mm) in the year for which the mean SS prediction is to be made. The findings highlight the need for water quality guidelines for SS to recognise natural spatial and temporal variations in SS within rivers. The findings also demonstrate the importance of the temporal resolution of SS sampling in determining assessments of compliance against water quality guidelines.

Fish functional traits correlated with environmental variables in a temperate biodiversity hotspot.

The global biodiversity crisis has invigorated the search for generalized patterns in most disciplines within the natural sciences. Studies based on organismal functional traits attempt to broaden implications of results by identifying the response of functional traits, instead of taxonomic units, to environmental variables. Determining the functional trait responses enables more direct comparisons with, or predictions for, communities of different taxonomic composition. The North American freshwater fish fauna is both diverse and increasingly imperiled through human mediated disturbances, including climate change. The Tennessee River, USA, contains one of the most diverse assemblages of freshwater fish in North America and has more imperiled species than other rivers, but there has been no trait-based study of community structure in the system. We identified 211 localities in the upper Tennessee River that were sampled by the Tennessee Valley Authority between 2009 and 2011 and compiled fish functional traits for the observed species and environmental variables for each locality. Using fourth corner analysis, we identified significant correlations between many fish functional traits and environmental variables. Functional traits associated with an opportunistic life history strategy were correlated with localities subject to greater land use disturbance and less flow regulation, while functional traits associated with a periodic life history strategy were correlated with localities subject to regular disturbance and regulated flow. These are patterns observed at the continental scale, highlighting the generalizability of trait-based methods. Contrary to studies that found no community structure differences when considering riparian buffer zones, we found that fish functional traits were correlated with different environmental variables between analyses with buffer zones vs. entire catchment area land cover proportions. Using existing databases and fourth corner analysis, our results support the broad application potential for trait-based methods and indicate trait-based methods can detect environmental filtering by riparian zone land cover.

Use of fish functional traits to associate in-stream suspended sediment transport metrics with biological impairment

Loss of ecological integrity due to excessive suspended sediment in rivers and streams is a major cause of water quality impairment in the USA. Current assessment protocols for development of sediment total maximum daily loads (TMDLs) lack a means to link temporally variable sediment transport rates with specific losses of ecological functions as loads increase. In order to accomplish this linkage assessment, a functional traits-based approach was used to correlate site occurrences of 17 fish species traits in three main groups (preferred rearing habitat, trophic feeding guild, and spawning behavior) with suspended sediment transport metrics. The sediment transport metrics included concentrations, durations, and dosages for a range of exceedance frequencies; and mean annual suspended sediment yields (SSY). In addition, this study in the Northwestern Great Plains Ecoregion examined trait relationships with three environmental gradients: channel stability, drainage area, and elevation. Potential stressor responses due to elevated suspended sediment concentration (SSC) levels were correlated with occurrences of five traits: preferred pool habitat; feeding generalists, omnivores, piscivores, and nest-building spawners; and development of ecologically based TMDL targets were demonstrated for specific SSC exceedance frequencies. In addition, reduced site occurrences for preferred pool habitat and nest-building spawners traits were associated with unstable channels and higher SSY. At an ecoregion scale, a functional traits assessment approach provided a means to quantify relations between biological impairment and episodically elevated levels of suspended sediment, supporting efforts to develop ecologically based sediment TMDLs.

Curve Numbers for Low-Compaction Steep-Sloped Reclaimed Mine Lands in the Southern Appalachians

AbstractIn the coal-mining region of the Appalachians, the Forestry Reclamation Approach (FRA) is currently promoted by the U.S. Dept. of Interior, Office of Surface Mining (OSM). FRA’s goal in establishing native forest cover on reclamation sites requires the use of loose spoils rather than traditionally compacted spoils during hillslope reconstruction. Loose spoils improve tree planting survival and enhance overall forest growth. Although FRA has been shown to be successful on low-gradient slopes without excessive runoff leading to erosion, rainfall-runoff relationships have not been studied on steep slopes (>20°) where most surface-mine reclamation typically occurs. A curve number (CN) range representing low-compaction steep-sloped conditions was needed for Appalachian FRA sites. Three active surface-mine sites in East Tennessee were monitored during a 1-year period (June 2009–July 2010) for rainfall (5-min intervals) and runoff hydrology (discharge volume, peak discharge) using a unique Pinson-type co...

Surface erosion and sediment yields on steep-sloped coal mining reclamation sites in the Appalachian Region.

Reclamation activities on coal mining sites to prevent excessive erosion have traditionally been very successful with the establishment of grass covers, on sites where the slopes are moderate to low. Establishment of native forest cover on reclaimed sites has become a priority directive of the US Department of Interior, Office of Surface Mining. However, standard construction techniques are based on slope stability criteria using high levels of compaction, resulting in poor soil medium for tree survival. A team of researchers at the University of Tennessee are engaged in studies with the overall objective to develop design criteria for stable steep slopes (∼28–35%), minimal erosion, and successful reforestation. A part of the overall project, the focus of this presentation provides a summary of the hydrological and erosion monitoring results at three experimental study sites on active coal mining locations in East Tennessee. Each site was equipped with a fully automated weather station, and consisted of four measurement plots. Sediment yields were measured using Pinson divider budgets following an H-flume and sedimentation tank. Initial results characterized pre-cover conditions in which erosion ranged from approximately < 1 ton to 10+ ton per event. Particle size distributions of the transported sediment from the hillslopes were also characterized. Results from this study will guide erosion control and detention pond design practices at early stages of coal mining reclamation, prior to reestablishment of native forest cover.

Hurst Analysis of Hydrologic and Water Quality Time Series

A continued important area of research in hydrologic modeling is the issue of spatial and temporal scaling of biogeochemical properties and processes. Hurst analysis, which is a fractal-based scale invariant approach for analyzing long-term time series data, can provide insight into this issue as a quantitative approach for evaluating temporal scale in time series. The objectives of this paper were to compute the Hurst coefficient (H) for hydrologic and water quality variables, to study the effects of seasonality on H, and to determine how the H for the water quality indicators are related to that of the hydrologic parameters (e.g., discharge and rainfall). Two sites were investigated, Little River and Walker Branch, both located in east Tennessee. The water quality indicators include total coliform for Little River data and nitrate, chloride, sulfate, and calcium concentrations for Walker Branch data. H was estimated using spectral analysis. It was found that H for water quality indicators were significa...

Sensitivity and uncertainty analysis of PnET-BGC to inform the development of Total Maximum Daily Loads (TMDLs) of acidity in the Great Smoky Mountains National Park

Abstract The biogeochemical model, PnET-BGC, has been used to evaluate the long-term acid-base response of surface waters to changes in atmospheric acid deposition. We propose a methodology to identify the input factors of greatest model sensitivity and propagate uncertainty of input factors to model outputs. The quantified model uncertainty enabled application of an “exceedance probability” approach to determine allowable atmospheric deposition in the form of Total Maximum Daily Loads (TMDLs) for twelve acid-impaired streams in Great Smoky Mountains National Park. Results indicate that acidification of surface water resulting from acidic deposition has been substantial. Even if current atmospheric deposition is reduced to pre-industrial levels, only one of the twelve impaired streams might be recovered to its site-specific standard by 2050. Our sensitivity analysis indicates that the model is most sensitive to precipitation quantity, air temperature and calcium weathering rate, and suggests further research to improve characterization of these inputs.

Use of River2D Hydrodynamic Model for Stream Restoration Assessment and Design

In urbanizing streams, the use of two-dimensional (2D) hydrodynamic models are essential for prediction of flow capacity channel stability, infrastructure protection, and physical habitat enhancement. River2D, a 2D hydrodynamic model has the capability to meet these needs for stream restoration assessment and design. As a restoration tool, depth-average and shear velocities for finite element cells within a mesh grid, which can be assessed for maximums spatially estimated throughout a design reach. Velocities can be estimated for current conditions and multiple design morphologies. Physical habitat quality can be assessed using species preferences for habitat suitability. Typically applied to fish species, weighted usable areas (WUAs) utilizing preferences for velocity, depth, and channel substrate are computed with River2D. Examples of model performance and their output’s use in the design process are presented for the: 1) Embarras River, Champaign County, Illinois; 2) West Prong of the Little Pigeon River, Sevier County, Tennessee; and 3) Beaver Creek, Knox County, Tennessee.

WinHSPF Model Simulations of Nitrogen and pH for a Low-Alkalinity Stream Impacted from Atmospheric Acid Deposition

The Hydrologic Simulation Program-Fortran (WinHSPF) was used to simulate the stream flow, ammonium, nitrate and pH for the No land Divide watershed from 1999 to mid-2006, to evaluate the model applicability to watersheds impacted by acidic deposition. Noland Divide watershed is located in the Great Smoky Mountains National Park, Tennessee. Model calibration for hydrology was satisfactory showing total error of 2.1% for stream discharge during simulation period. The model simulated low ammonium concentration (0.04 mgN L –1 ) in the stream, which is likely due to the high nitrification rate on the land converting most deposited ammonium to nitrate. The deviation between the simulated and measured nitrate concentration was 0.03 mgN L –1 while the mean observed nitrate concentration was 0.57 mgN L –1 . Although the model output for pH (from 5.7 to 6.0) were similar to observed stream pH measurements (from 5.5 to 6.5), model calculations of pH did not consider stream acidification due to mineral anion acids. The WinHSPF model computes pH simply based on carbonate system and alkalinity equilibrium, and therefore is only applicable to waterbodies governed by the carbonate-dominated chemistry. In low alkalinity waters like those found in the Noland Divide watershed, WinHSPF can not predict stream chemistry response from impacts of acidic deposition.