High-frequency Concentration and Discharge Data for Augusta Creek, Michigan

Concentration and discharge data for a high-frequency analysis of storm event dynamics at a Wetland Inlet, a Wetland Outlet, and a downstream Main Stem site in Augusta Creek, Michigan. We collected this high-frequency data beginning 25 April 2023 at the Wetland Inlet and Outlet, and 24 May 2023 at the Main Stem, with data collection ending on 28 November 2023. Concentration data includes dissolved organic carbon (DOC) and nitrate (NO3-), collected every 15 minutes using in-situ ultraviolet spectrophotometers (s::can Messtechnik GMbH, Vienna, Austria), that measure light absorbance wavelengths of 220 to 750 nm. These spectrophotometers were deployed in PVC tubes mounted in the stream channel, and powered by battery and solar panels mounted on the banks. To determine concentration values, we created site specific calibrations using partial least square regression (PLSR) models based on grab samples of DOC and NO3- collected every two weeks. Grab samples were vacuum filtered within 24 hours of field collection using 0.45 um cellulose acetate filters (Sartorius, 11106--47------N) and polysulfone filter towers triple rinsed with sample water. To measure DOC (as NPOC, non-purgeable organic carbon, mg/L), we used a total organic carbon analyzer (Shimadzu TOC-L CPH/CPN and autosampler ASI-L). To measure NO3- (as NO3--N, converted to NO3-), we used an ion chromotography system (Thermo Fisher Dionex, ICS1100 and ICS1000 and AS-DV autosampler). Our method detection limits were: 0.02 mg L-1 for nitrate and 0.43 mg L-1 for DOC. Values that are \"BDL\" were below instrument detection limit. For values below method or instrument detection limit, we assigned concentrations of half the limit of quantification for the purpose of calculations and analyses. If this data is used in the future, values below the method detection limit will need to be filtered appropriately. Values that are NA were not analyzed. Discharge data was measured by converting high-frequency water level data to continuous discharge data using discrete discharge measurements and a discharge-water level rating curve. Water level was calculated using pressure transducers (PT) co-located with barometric pressure loggers (Onset HOBO, Bourne Massachusetts) to determine above-sensor pressure every 15 minutes.

This data supports the paper:
Evaluating Wetland Influence on Downstream Carbon and Nitrate Dynamics During Storms in a Low-Relief Catchment
Authors: Caroline R. Weidner, Jay P. Zarnetske, Arsh Grewal, Arial J. Shogren