Hydrology:
Head (water-level) - A Schlumberger Micro-Diver (DI601) pressure
transducer was deployed in a manually installed stream gauge to record
surface water head, and Schlumberger Baro (DI500) pressure transducers
were deployed in three manually installed shallow piezometers to
record subsurface head levels at ~35 cm depth; calculations accounted
for the contribution of air pressure recorded by an additional
Schlumberger Baro. Two of the piezometers were deployed at the main
monitoring/sampling sites: in the center of the stream channel, and in
the west-flanking wetland sufficiently close to the channel such that
inundated conditions persisted throughout the summer. To assess
variability within Second Creek, the third piezometer was deployed
between the first two locations in the channel near its west bank.
Temperature - Vertical temperature probes collocated with the
piezometers measured porewater temperature at 0, 5, 10, 15, 20, and 30
cm depths below the sediment-water interface. The temperature probes
were constructed using wooden dowels, housed thermistors potted at the
dowel surface in waterproof epoxy, and were connected to an
open-source “ALog” data-logger (an intermediary version between that
presented in Wickert [2014] and Wickert et al. [2018].
Flux - Time series data of temperature profile and hyporheic zone head
gradients in the center channel, west wetland, and west channel were
incorporated in the heat-transport inverse model 1DTempPro [Voytek et
al., 2014] to estimate the time series of hyporheic flux at each
location. For parameters required by 1DTempPro model, we used sediment
porosity of 0.51 previously measured by Myrbo et al. [2017], thermal
conductivity of 0.56 W/m/C, and saturated heat capacity of 2.44 × 10 6
J/m^3/C estimated assuming 80% sediment organic matter and 20%
siliciclastic material in the approach by Farouki [1986], and heat
dispersivity of 0.1 m assigned based on typical solute dispersivity
for the tens of centimeters spatial scale considered here [Zheng and
Bennett, 2002].
Water chemistry:
On June 14 and August 15, 2016, we sampled porewater at 1.56 cm depth
intervals from 1.56 cm above the sediment-water interface to about
40-50 cm depth below the interface using passive porewater
equilibrators (“peepers”) following the method described in Ng et al.
[2017]. In June, duplicate peepers were deployed in the channel and
wetland monitoring/sampling locations. In August, duplicate peepers
were deployed again in the channel; intended peeper deployment in the
wetland in August was later found to be mislocated in channel
sediments and failed to capture actual wetland conditions. For all
peeper samples, pH was analyzed in the field using a Thermo Scientific
Orion STAR A329. Fe^2+ was quantified in the field using the
phenanthroline method [Eaton et al., 2005]. Methane samples were
collected and analyzed using the same methods described in [Ng et al.,
2017]. For select peeper samples, we acidified cation samples of about
12 mL volume with one drop of 6N HCl before analysis using a Thermo
Scientific iCAP 6500 dual view ICP-OES (for Al, Ba, Ca, Fe, K, Li, Mg,
Mn, Na, P, Si, and Sr) at University of Minnesota, Twin Cities; anion
samples were analyzed using a Thermo Dionex ICS 5000+ ion
chromatography system (for F−, Cl− ,NO3− ,Br− , and SO4^2− ) at
University of Minnesota, Twin Cities.
References:
Eaton, D. A., L. S. Clesceri, and others (2005), Standard Methods for
the Examination of Water & Wastewater–3500-Fe- B. Phenanthroline
Method.
Farouki, O. (1986), Thermal properties of soils, 136 pp., Trans Tech
Publications, Limited, Clausthal-Zellerfeld, Germany.
Myrbo, A., E. B. Swain, D. R. Engstrom, J. Coleman Wasik, J. Brenner,
M. Dykhuizen Shore, E. B. Peters, and G. Blaha (2017), Sulfide
Generated by Sulfate Reduction is a Primary Controller of the
Occurrence of Wild Rice ( Zizania palustris ) in Shallow Aquatic
Ecosystems, Journal of Geophysical Research: Biogeosciences, 122(11),
2736–2753, doi:10.1002/2017JG003787.
Ng, G.-H. C., A. R. Yourd, N. W. Johnson, and A. E. Myrbo (2017),
Modeling hydrologic controls on sulfur processes in sulfate-impacted
wetland and stream sediments, Journal of Geophysical Research:
Biogeosciences, 122(9), 2435–2457, doi:10.1002/2017JG003822.
Voytek, E. B., A. Drenkelfuss, F. D. Day-Lewis, R. Healy, J. W. Lane,
and D. Werkema (2014), 1DTempPro: Analyzing Temperature Profiles for
Groundwater/Surface-water Exchange, Groundwater, 52(2), 298–302,
doi:10.1111/gwat.12051.
Wickert, A. D. (2014), The ALog: Inexpensive, Open-Source, Automated
Data Collection in the Field, Bulletin of the Ecological Society of
America, 95(2), 166–176, doi:10.1890/0012-9623-95.2.68.
Wickert, A. D., C. T. Sandell, B. Schulz, and G.-H. C. Ng (2018),
Open-source Arduino-derived data loggers designed for field research,
Hydrology and Earth System Sciences, (December), 1–16,
doi:10.5194/hess-2018-591.
Zheng, C., and G. D. Bennett (2002), Applied Contaminant Transport
Modeling, 2nd ed., 656 pp., Wiley and Sons, New York, NY