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Boulder City, WI, United States

Watras C.J.,UW Trout Lake Research Station | Watras C.J.,University of Wisconsin - Madison | Hanson P.C.,University of Wisconsin - Madison | Stacy T.L.,University of Wisconsin - Madison | And 5 more authors.
Limnology and Oceanography: Methods | Year: 2011

The effect of temperature on CDOM fluorescence was investigated in dystrophic freshwaters of Wisconsin and in aqueous standards. Laboratory experiments with two commercial in situ fluorometers showed that CDOM fluorescence intensity decreased as ambient water temperature increased. A temperature compensation equation was derived to standardize CDOM fluorescence measurements to a specific reference temperature. The form of the equation is: CDOM r = CDOM m/[1 + ρ(T m - T r)], where T is temperature (°C), ρ is the temperaturespecific coefficient of fluorescence (°C-1), and the subscripts r and m stand for the reference and measured values. (We note that an analogous function is used widely to calculate temperature-specific conductance from the measured conductivity of natural waters.) For the two sensors we tested, the temperature-specific fluorescence coefficients (r) were -0.015 ± 0.001 and -0.008 ± 0.0008 for Wisconsin bog waters at 20°C. When applied to field data, temperature compensation removed the effect of multi-day trends in water temperature, and it also damped the diel CDOM cycle. We conclude that temperature compensation is a necessary and important aspect of CDOM monitoring using in situ fluorescence sensors. © 2011, by the American Society of Limnology and Oceanography, Inc.

Watras C.J.,UW Trout Lake Research Station | Watras C.J.,University of Wisconsin - Madison | Morrison K.A.,UW Trout Lake Research Station | Morrison K.A.,University of Wisconsin - Madison | And 3 more authors.
Limnology and Oceanography: Methods | Year: 2014

A method recently proposed by Ryder et al. (2012) as the preferred way to compensate for temperature quenching of CDOM fluorescence is mathematically equivalent to the prior method that they claim to improve upon. © 2014, by the American Society of Limnology and Oceanography, Inc.

Watras C.J.,UW Trout Lake Research Station | Watras C.J.,University of Wisconsin - Madison | Morrow M.,University of Wisconsin - Madison | Morrison K.,UW Trout Lake Research Station | And 8 more authors.
Environmental Monitoring and Assessment | Year: 2014

Here, we describe and evaluate two low-power wireless sensor networks (WSNs) designed to remotely monitor wetland hydrochemical dynamics over time scales ranging from minutes to decades. Each WSN (one student-built and one commercial) has multiple nodes to monitor water level, precipitation, evapotranspiration, temperature, and major solutes at user-defined time intervals. Both WSNs can be configured to report data in near real time via the internet. Based on deployments in two isolated wetlands, we report highly resolved water budgets, transient reversals of flow path, rates of transpiration from peatlands and the dynamics of chromophoric-dissolved organic matter and bulk ionic solutes (specific conductivity) - all on daily or subdaily time scales. Initial results indicate that direct precipitation and evapotranspiration dominate the hydrologic budget of both study wetlands, despite their relatively flat geomorphology and proximity to elevated uplands. Rates of transpiration from peatland sites were typically greater than evaporation from open waters but were more challenging to integrate spatially. Due to the high specific yield of peat, the hydrologic gradient between peatland and open water varied with precipitation events and intervening periods of dry out. The resultant flow path reversals implied that the flux of solutes across the riparian boundary varied over daily time scales. We conclude that WSNs can be deployed in remote wetland-dominated ecosystems at relatively low cost to assess the hydrochemical impacts of weather, climate, and other perturbations. © 2013 Springer Science+Business Media Dordrecht.

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