No description available.

No description available.

No description available.

No description available.

No description available.

The Wissahickon Creek is an urban stream that runs through Montgomery and Philadelphia Counties and discharges to the Schuylkill River in Philadelphia. A majority of stream segments in the Wissahickon watershed are considered impaired by the USEPA due to sediment and nutrients. Total Maximum Daily Loads (TMDLs) were implemented in 2003 for nutrients (NO3-, PO43-, NO2-, and CBOD5) and siltation. A new TMDL for total phosphorus (TP) was proposed in 2015, despite minimal data on the effectiveness of the 2003 TMDLs. This new proposal was met with concern, suggesting more data must be collected to better understand impairment in the Wissahickon Creek. The purpose of this research was to study turbidity and nutrient responses to storm events, as storm events are known to contribute significant loads of both sediment and nutrients. Twelve sites were chosen for high frequency turbidity and water level monitoring along the Wissahickon Creek and one of its main tributaries, Sandy Run. These sites were selected around three of the major wastewater treatment plants (WWTPs) to determine the relative roles of WWTPs and overland flow as sources of turbidity and nutrients during storm events. The upstream site and first downstream site at each WWTP were monitored for nutrients during storms using high frequency loggers and ISCO automatic samplers. Stream assessments were done at each site to characterize in-stream physical parameters, bank vegetation, and algae cover. High frequency turbidity data suggests that the turbidity is locally sourced, as turbidity peaks at the same time as water level, or within an hour or two, at all sites regardless of storm size. Comparisons of the turbidity response with in-stream parameters and land cover helped determine that the main factor driving the turbidity response is discharge, although bank topping and impervious cover, particularly roads, may increase turbidity responses at some sites. Similarities in nutrient, turbidity, and conductivity responses upstream and downstream of the WWTPs strongly suggest that overland flow, not WWTP effluent, is the major source of nutrients and sediment during storm events. Finally, a strong relationship between total phosphorus and high turbidity suggests that only during high discharge events is there a significant increase in TP in the Wissahickon Creek. Results from this research identify the source of turbidity and nutrients to the Wissahickon Creek during storms as primarily coming from overland flow, that the primary factor controlling the turbidity response is discharge, with some secondary influence from over-banking and the contribution of roads to land use, and a close link between TP concentrations and sediment during storms in the stream. / Geology

<p>Validerat; 20111223 (anonymous)</p>

Eutrophication is a global problem that has a major impact on aquatic ecosystems. Over the past 50 years, the nutrient content of lakes and streams has increased as a result of urban development and agricultural sources. It can cause health problems for both humans and animals through direct contact or when consumed. In addition, it can result in the extinction of aquatic organisms. By studying the topography, soil chemistry, hydrology and human impact of areas, we can understand how nutrients are transported from their sources of origin to surface water, where they increase nutrient content. Understanding this is crucial to identify and prioritise areas that require action to reduce the effects of eutrophication. The purpose of this study was to trace potential sources of dispersion of nutrients to the surface water through analysis of these. The site chosen for the study was the area of Tvärålund where the stream Sjöbäcken and lake Tväråträsket are located, where 11 sampling points were also placed. These had the purpose of proving any emissions from ancillary activities. The results indicate that only one of the selected sampling points was contaminated from active point sources (individual sewers) while the remaining points showed a constant increase supported by a linear relationship between distance from the reference point and measured concentration.

The U.S. EPA has identified pathogen indicators as a leading cause of impairments in rivers and streams in the U.S. Elevated levels of bacteria in streams draining the agricultural watersheds cause concern because they indicate the potential presence of pathogenic organisms. Limited understanding of how bacteria survive in the environment and are released from fecal matter and transported along overland flow pathways results in high uncertainty in the design and selection of appropriate best management practices (BMPs) and in the bacterial fate and transport models used to identify sources of pathogens. The overall goal of this study was to improve understanding of the fate and transport mechanisms of two pathogen indicators, E. coli and enterococci, from grazed pasturelands. This goal was addressed by monitoring pathogen indicator concentrations in fresh fecal deposits for an extended period of time. Transport mechanisms of pathogen indicators were examined by developing a method to partition between the attached and unattached phases and then applying this method to analyze runoff samples collected from small box plots and large transport plots. The box plot experiments examined the partitioning of pathogen indicators in runoff from three different soil types while the transport plot experiments examined partitioning at the edge-of-the-field from well-managed and poorly-managed pasturelands. A variety of techniques have been previously used to assess bacterial attachment to particulates including filtration, fractional filtration and centrifugation. In addition, a variety of chemical and physical dispersion techniques are employed to release attached and bioflocculated cells from particulates. This research developed and validated an easy-to-replicate laboratory procedure for separation of unattached from attached E. coli with the ability to identify particle sizes to which indicators preferentially attach. Testing of physical and chemical dispersion techniques identified a hand shaker treatment for 10 minutes followed by dilutions in 1,000 mg L-1 of Tween-85 as increasing total E. coli concentrations by 31% (P value = 0.0028) and enterococci concentrations by 17% (P value = 0.3425) when compared to a control. Separation of the unattached and attached fractions was achieved by fractional filtration followed by centrifugation. Samples receiving the filtration and centrifugation treatments did not produce statistically different E. coli (P value = 0.97) or enterococci (P value = 0.83) concentrations when compared to a control, indicating that damage was not inflicted upon the cells during the separation procedure. In-field monitoring of E. coli and enterococci re-growth and decay patterns in cowpats applied to pasturelands was conducted during the spring, summer, fall and winter seasons. First order approximations were used to determine die-off rate coefficients and decimal reduction times (D-values). Higher order approximations and weather parameters were evaluated by multiple regression analysis to identify environmental parameters impacting in-field E. coli and enterococci decay. First order kinetics approximated E. coli and enterococci decay rates with regression coefficients ranging from 0.70 to 0.90. Die-off rate constants were greatest in cowpats applied to pasture during late winter and monitored into summer months for E. coli (k = 0.0995 d-1) and applied to the field during the summer and monitored until December for enterococci (k = 0.0978 d-1). Decay rates were lowest in cowpats applied to the pasture during the fall and monitored over the winter (k = 0.0581 d-1 for E. coli and k = 0.0557 d-1 for enterococci). Higher order approximations and the addition of weather variables improved regression coefficients (R2) to values ranging from 0.81 to 0.97. Statistically significant variables used in the models for predicting bacterial decay included temperature, solar radiation, rainfall and relative humidity. Attachment of E. coli and enterococci to particulates present in runoff from highly erodible soils was evaluated through the application of rainfall to small box plots containing different soil types. Partitioning varied by indicator and by soil type. In general, enterococci had a higher percent attached to the silty loam (49%) and silty clay loam (43%) soils while E. coli had a higher percent attached to the loamy fine sand soils (43%). At least 50% of all attached E. coli and enterococci were associated with sediment and organic particles ranging from 8 – 62 μm in diameter. Much lower attachment rates were observed from runoff samples collected at the edge-of-the-field, regardless of pastureland management strategy. On average, 4.8% of E. coli and 13% of enterococci were attached to particulates in runoff from well-managed pasturelands. A second transport plot study found that on average only 0.06% of E. coli PC and 0.98% of enterococci were attached to particulates in runoff from well-managed pasturelands, but percent attachment increased slightly in runoff from poorly-managed pasture with 2.8% of E. coli and 1.23% of enterococci attached to particulates. Equations to predict E. coli and enterococci loading rates in the attached and unattached forms as a function of total suspended solids (TSS), phosphorous and organic carbon loading rates appeared to be a promising tool for improving prediction of bacterial loading rates from grazed pasturelands (R2 values ranged from 0.61 to 0.99). This study provides field-based seasonal die-off rate coefficients and higher order approximations to improve predictions of indicator re-growth and decay patterns. The transport studies provide partitioning coefficients that can be implemented into NPS models to improve predictions of bacterial concentrations in surface waters and regression equations to predict bacterial partitioning and loading based on TSS and nutrient data. Best management practices to reduce bacterial loadings to the edge-of-the-field from pasturelands (regardless of management strategy) should focus on retention of pathogen indicators moving through overland flow pathways in the unattached state. Settling of particulates prior to release of runoff to surface waters might be an appropriate method of reducing bacterial loadings by as much as 50% from highly erodible soils. / Ph. D.

I investigated the baseline benthic macroinvertebrate community in relation to the environmental conditions in a section of Smith Creek, north of Harrisonburg, VA, prior to restoration. Quantitative benthic macroinvertebrate and environmental samples were collected in April and September 2006 from the Bruce Farm (BR) section of Smith Creek and the nearby Mixed Use (MU) section of Mountain Run. BR had been heavily used for cattle grazing for decades and suffered from sediment, nutrients, and lack of a forested riparian zone. MU had a forested riparian zone, but still received nutrient and sediment inputs from upstream cattle grazing. Visual habitat assessments were performed in September 2006 and were compared to quantitative measures. Benthic macroinvertebrate densities and taxa richness were greater at BR (total density for combined seasons = 52,438; taxa richness for both seasons = 84) than MU (total density for combined seasons = 3,982 and taxa richness for both seasons = 63). Biological environmental variables related to nutrients and growth of plants on rocks (ash-free dry mass, chlorophyll a, epilithic biomass) influenced the benthic macroinvertebrate assemblage more than physical environmental variables related to the substrate composition (% fines, % gravel, Trask's sorting coefficient). Visual habitat estimates were not as effective as quantitative measures of habitat for explaining the benthic macroinvertebrate assemblage. / Master of Science