Accompanying Data to Hampton et al. (2020) Experimental shifts of hydrologic residence time in a sandy urban stream sediment-water interface alter nitrate removal and nitrous oxide fluxes

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Abstract

The sediment-water interfaces (SWI) of streams serve as important biogeochemical hotspots in watersheds and contribute to whole-catchment reactive nitrogen budgets and water-quality conditions. Recently, the SWI has been identified as an important source of nitrous oxide (N2O) produced in streams, with SWI residence time among the principal controls on its production. Here, we conducted a series of controlled manipulations of SWI exchange in an urban stream that has high dissolved N2O concentrations and where we concurrently evaluated less-mobile porosity dynamics. Our experiments took place within isolated portions of two sediment types: a coarse sandy stream bed resulting from excess road-sand application in the watershed, and a coarse sand mixed with clay and organic particles. In these manipulation experiments we systematically varied SWI vertical-flux rates and residence times to evaluate their effect on the fate of nitrate and production rates of N2O. Our experiments demonstrate that the fate and transport of nitrate and N2O production are influenced by hydrologic flux rates through SWI sediments and associated residence times. Specifically, we show that manipulations of hydrologic flux systematically shifted the depth of the bulk oxic-anoxic interface in the sediments, and that nitrate removal increased with residence time. Our results also support the emerging hypothesis of a ‘Goldilocks’ timescale for the production of nitrous oxide, when transport and reaction timescales favor incomplete denitrification. Areal N2O production rates were up to 3-fold higher during an intermediate residence-time experiment, compared to shorter or longer residence times. In our companion study we documented that the studied sediments were dominated by a long-residence-time less-mobile porosity domain, which could explain why we observed N2O production even in bulk-oxic sediments. Overall, we have experimentally demonstrated that changes to SWI hydrologic residence times and SWI substrate associated with urbanization can change the biogeochemical function of the river corridor.

Resource Level Coverage

Spatial

Coordinate System/Geographic Projection:
WGS 84 EPSG:4326
Coordinate Units:
Decimal degrees
North Latitude
42.5288°
East Longitude
-71.1711°
South Latitude
42.5212°
West Longitude
-71.1891°

Content

Tyler Hampton 2020-02-14

Intro

This R Markdown README file accompanies Hampton et al. (2020): Experimental shifts of hydrologic residence time in a sandy urban stream sediment-water interface alter nitrate removal and nitrous oxide fluxes

Corresponding Author Information: Tyler B. Hampton Email: tyler.hampton@uwaterloo.ca; ORCID: https://orcid.org/0000-0003-1087-2059

This document details the scripts and data accompanying this Rproject

Scripts

r list.files(pattern=".R")

## [1] "README.Rmd"
## [2] "SawmillBrook_dataanalysis_20200214.R"
## [3] "SawmillBrook_paperfigures_20200214.R"
## [4] "SawmillBrook_Rproj.Rproj"


“SawmillBrook_dataanalysis_20200214.R” This is the primary script accompanying this publication. Running it in its entirety will process all the raw data, create figures in the figures folder and write all datasets to the outdata folder.

“SawmillBrook_dataanalysis_20200214.R” This script is called by dataanalysis and processes the input data for a given subset of parameters.

Input Files

r list.files(path="input")

## [1] "otherstudiesDENrates.csv"  "otherstudiesDENrates.xlsx"
## [3] "SawB_rawdata.csv"          "SawB_timedata.csv"
## [5] "SMBcaption.png"


“SMBcaption.png”
A PNG file that serves as a caption for all plots

“otherstudiesDENrates.csv” This data accompanies Figure 9. The columns are:

• study: A shortened name of the study. See the manuscript for paper citations

• Denrate: Areal denitrification rates from the study, all units are (\mu)mol m-2 hr-1

“otherstudiesDENrates.xlsx” This xlsx file contains the same data in the csv sorted by study, including calculations to convert study units to the units used in the csv file

“SawB_timedata.csv” This csv contains the fluid residence times (in hours) measured at each sediment depth (0,5,10,15,20 cm) for each experiment. The columns are:

• Exp: a text string with the experiment flux rate appended with the ring, so 3 m/d US is for the short residence time experiment in ring US

• Depth [cm]: the sediment depth in centimeters

• time [hr]: the fluid residence time in hours

“SawB_rawdata.csv” This csv file contains all the chemical concentrations used in this study. Though the data are from different sources or instruments, see methods section of paper, they are all sorted by individual sample. The columns are:

• Flux.Ring: a text string with the experiment flux rate appended with the ring, so 3 m/d US is for the short residence time experiment in ring US. Same as “Exp” column for “SawB_timedata.csv”

• Depth.cm.: the sediment depth in centimeters

• Time.hours.: the fluid residence time in hours

• XsampleN2: measured 15N atom percent (15/(15+14)) in N2 gas from solution

• XsampleN2O: measured 15N atom percent (15/(15+14)) in N2O gas from solution

• XsampleNO3: measured 15N atom percent (15/(15+14)) in NO3 in solution

• d15N2: measured del 15N enrichment in N2 gas from solution

• N2.uM: concentration of N2 gas in porewater, in (\mu)mol N L-1. See methods for calculation in Hampton MS Thesis: https://d.lib.msu.edu/etd/16393

• N2O.uM: concentration of N2O gas in porewater, in (\mu)mol N L-1. See methods for calculation in Hampton MS Thesis

• N2x15N2: concentration of N2 gas in porewater multiplied by XsampleN2, in (\mu)mol N L-1

• N2Ox15N2O: concentration of N2O gas in porewater multiplied by XsampleN2O, in (\mu)mol N L-1

• NO3.uM: concentration of NO3 in solution in (\mu)mol N L-1

• NO3x15NO3: concentration of NO\~3 in porewater multiplied by XsampleNO3, in (\mu)mol N L-1

• O2.uM: concentration of dissolved O2 in porewater, in in (\mu)mol O2 L-1

• C.uM: concentration of dissolved organic carbon (DOC) in porewater, in in (\mu)mol C L-1

Output Files

r list.files(path="outdata")

## [1] "publish_means2.csv"    "publish_Ratesk.csv"    "publish_RatesU.csv"
## [4] "SawB_means.csv"        "SawB_N2Oexport.csv"    "SawB_uptakewhole.csv"
## [7] "SawB_uptakewholeK.csv" "TableSM1.csv"          "TableSM2.csv"


“TableSM1.csv” This csv file contains the data from Supplementary Materials Table 1, showing sediment percent sand and organic carbon with depth for the two rings.

“TableSM2.csv” This csv file contains reaction rates as k and U from the experiments, rounded with error estimates in parentheses next to each measurement.

“SawB_means.csv” This csv file contains mean concentrations and standard deviation for each chemical, per experiment and depth. Columns are the same as for “SawB_rawdata.csv” except for column “type”.

• type: one of “M” or “sd” for mean or standard deviation.

“publish_means2.csv” This csv is the same as “SawB_means.csv” but means are rounded and grouped with standard deviation in parentheses

“SawB_uptakewhole.csv” This csv file contains reaction rates (U) summarized in TableSM2, tall format Columns:

• chem: one of the chemical columns from “SawB_rawdata.csv”, specifying the reaction rates for that species.

• plot: the reaction rate, in (\mu)mol m-2 hr-1

• err: the reaction rate standard error, in (\mu)mol m-2 hr-1

“SawB_uptakewholeK.csv” This csv file contains reaction rates (k) summarized in TableSM2, tall format

“SawB_N2Oexport.csv” This csv contains the output data summarized for N2O in TableSM2 Columns:

• N2O.umold: the concentration of N2O multiplied by the flux rate, units are (\mu)mol d-1

• N2O.umold.stdev: the standard deviation of N2O concentrations, multiplied by the flux rate, units are (\mu)mol d-1

• print: the rounded values shown in TableSM2, derived from the prior two columns

“publish_RatesU.csv” This csv file contains rounded reaction rates with error (U) summarized in TableSM2, wide format

“publish_Ratesk.csv” This csv file contains rounded reaction rates with error (k) summarized in TableSM2, wide format

Credits

Funding Agencies

This resource was created using funding from the following sources:
Agency Name Award Title Award Number
National Science Foundation EAR-1446328, EAR-1446300, and EAR-1446375
U.S. Geological Survey Toxic Substances Hydrology Program

How to Cite

Hampton, T. B. (2020). Accompanying Data to Hampton et al. (2020) Experimental shifts of hydrologic residence time in a sandy urban stream sediment-water interface alter nitrate removal and nitrous oxide fluxes, HydroShare, https://doi.org/10.4211/hs.ded08cce17244dbf871a437c3b333d03

This resource is shared under the Creative Commons Attribution CC BY.