Surface transient storage (STS) has functional significance in stream ecosystems because it increases solute interaction with sediments. After volume, mean residence time is the most important metric of STS, but it is unclear how this can be measured accurately or related to other timescales and field-measureable parameters. We studied mean...
1. Temperature is a major driver of ecological processes in stream ecosystems, yet the dynamics of
thermal regimes remain poorly described. Most work has focused on relatively simple descriptors
that fail to capture the full range of conditions that characterise thermal regimes of streams across
seasons or throughout the year....
Current stream tracer techniques do not allow separation of in-channel dead zone (e.g., eddies) and out-of-channel (hyporheic) transient storage, yet this separation is important to understanding stream biogeochemical processes. We characterize in-channel transient storage with a rhodamine WT solute tracer experiment in a 304 m cascade-pool-type bedrock reach with no...
A “smart” tracer is a tracer that provides, directly or through measurement of its concentration or in combination with another compound, at least one “bit” more of information about the environment through which it travels than a conservative tracer. In this study we propose and present the chemical compound resazurin...
Previous field-scale experimental data and numerical modeling suggest that the dual-domain mass transfer (DDMT) of electrolytic tracers has an observable geoelectrical signature. Here we present controlled laboratory experiments confirming the electrical signature of DDMT and demonstrate the use of time-lapse electrical measurements in conjunction with concentration measurements to estimate the...
Stream temperature will be subject to changes because of atmospheric warming in the future. We investigated the effects of the diurnal timing of air temperature changes – daytime warming versus nighttime warming – on stream temperature. Using the physically based model, Heat Source, we performed a sensitivity analysis of summer...
Biogeochemical reactions associated with stream nitrogen cycling, such as
nitrification and denitrification, can be strongly controlled by water and solute residence
times in the hyporheic zone (HZ). We used a whole‐stream steady state ¹⁵N‐labeled
nitrate (¹⁵NO₃⁻) and conservative tracer (Cl⁻) addition to investigate the spatial and
temporal physiochemical conditions controlling...
In a set of streamside mesocosms, stream ecosystem respiration (ER) increased with biofilm biomass and flow heterogeneity (turbulence) generated by impermeable bed forms, even though those bed forms had no hyporheic exchange. Two streamside flumes with gravel beds (single layer of gravel) were operated in parallel. The first flume had...
In field studies of solute transport, transient storage within lateral cavities and other stream features generates
breakthrough curves (BTCs) with pronounced and persistent skewness. Current solute transport
theory requires that the coefficient of skewness (CSK) decrease over time because the system eventually
reaches Fickian conditions. However, published data show that...
Flow and temperature are strongly linked environmental factors driving ecosystem processes in streams. Stream temperature maxima (T [subscript max_w]) and stream flow minima (Q[subscript min]) can create periods of stress for aquatic organisms. In mountainous areas, such as western North America, recent shifts toward an earlier spring peak flow and...