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Sheila F Murphy

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Slug additions are often the most accurate method for determining discharge when traditional current meter or acoustic measurements are unreliable because of high turbulence, rocky streambed, shallow or sheet flow, or the stream is physically inaccessible (e.g., under ice or canyon walls) or unsafe to wade (Zellweger et al., 1989, Kilpatrick and Cobb 1984, Ferranti 2015). The slug addition method for determining discharge requires an injection of a known amount of a single salt and high-frequency downstream measurement of solute concentration to capture the response curve (Kilpatrick and Cobb 1984). A new slug method was developed to determine stream discharge utilizing specific conductance and ionic molal conductivities...
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Multiple sampling campaigns were conducted near Boulder, Colorado, to quantify constituent concentrations and loads in Boulder Creek and its tributary, South Boulder Creek. Diel sampling was initiated at approximately 1100 hours on September 17, 2019, and continued until approximately 2300 hours on September 18, 2019. During this time period, samples were collected at two locations on Boulder Creek approximately every 3.5 hours to quantify the diel variability of constituent concentrations at low flow. Synoptic sampling campaigns on South Boulder Creek and Boulder Creek were conducted October 15-18, 2019, to develop spatial profiles of concentration, streamflow, and load. Numerous main stem and inflow locations...
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Atmospheric deposition of reactive nitrogen (Nr) due to human activities can have measurable effects on ecosystem processing and export of nutrients, groundwater and surface-water quality. Rates of Nr deposition to lower-elevation forests immediately adjacent to the Denver/Boulder urban area, however, have only recently been measured. The focus of this study was to determine the extent of urban and agricultural N pollution transport to the Colorado Front Range. In conjunction with the Network for Urban Atmospheric Nitrogen Chemistry (NUANC) and the National Atmospheric Deposition Program (NADP), we measured wet-plus-dry Nr deposition and evaluated spatial and seasonal variations in N deposition along an elevational...
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Atmospheric deposition of reactive nitrogen (Nr) can impact the soil microbial community structure and function and thus ecosystem processing and export of nutrients. Ecosystem response to atmospheric inputs of nitrogen depends on several factors, including elevational climate conditions (freeze/thaw cycles, precipitation), geology, soil and vegetation type, N speciation and microbial community structure. The focus of this study was to evaluate how spatial and seasonal variations in N deposition affect the ability of soil microbial communities to process N along an elevational gradient (1700 to 3015 meters) from plains to subalpine ecosystems west of Boulder, Colorado. In conjunction with a study measuring the variability...
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Post Wildfire Hydrological, Sedimentological, and Water Quality Responses
This is a multi-disciplinary community of scientists who study the effects of wildfire disturbance on the built and natural environment. The mission is to understand natural processes such as infiltration, rainfall-runoff, erosion, sediment and chemical transport, and water quality effects. The focus is on obtaining field-based measurements that can be used to improve or develop models for use by emergency, land and water supply managers as tools for decision making.
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