1. Measurement methods
Each description below is cross-referenced with the brief methods
caption provided in the descriptions of the table columns.
Deployed SAMI CO2 probe: A Submersible Autonomous Moored Instrument
(SAMI) CO2 probe was deployed directly in the channel thalweg and
measured the partial pressure of dissolved CO2 in river water. The pH
of the indicator fluid measured by colorimetric absorbance can then be
calibrated to the influence of dissolved carbon dioxide gas on the
buffering system of the indicator. Calibrations were carried out in
the DeGrandpre lab at University of Montana. The probe also records
the water temperature and time of measurements.
Deployed SAMI pH probe: A Submersible Autonomous Moored Instrument
(SAMI) pH probe was deployed directly in the channel thalweg and
measured pH in the river water. Samples of river water are
automatically pumped into the SAMI and are passively mixed with
indicator dye. A spectrophotometric measurement of the mixture
provides a value for pH. The probe also records the water temperature
and time of measurements.
Deployed HOBO EC probe: A Hobo ONSET electrical conductivity probe was
deployed directly in the channel thalweg and measured the
temperature-corrected electrical conductivity in river water. The
electrical conductivity is measured by applying a voltage across leads
with a specific geometry of connection with river water and measuring
the resistance between those leads to conducting an electrical
current. The probe also records the water temperature and time of
measurements. The software from the manufacturer of the probe (Hobo
Onset) provides a post-processor that performs the
temperature-correction of the conductivity to 25 degrees Celsius. The
factory calibration was used on the instrument.
Deployed HOBO pressure probe: A Hobo ONSET pressure transducer was
deployed with the SAMI CO2 probe to track the relative variation in
river depth during the deployment. The pressure transducers derives
absolute pressure by measuring the deformation of a ceramic diaphragm.
The probe also records the water temperature and time of measurements.
The following methods apply to data collected for quality assurance.
The data have not been altered based on these measurements, and they
are provided for information to future users of these data.
Colorimetry with indicator dye: For quality assurance purposes, pH of
discrete river water samples was measured in a laboratory setting
following the procedures in Lai et al. (2016). Briefly, indicator dyes
were added to river samples stored in a 10-cm cylindrical optical
cell. Values of pH for the samples were obtained by monitoring the
spectrum of the dye-sample mixture via a Cary 300 spectrophotometer
(Varian, Inc.). Measurements are routinely performed at ~20 °C and
corrected to in situ temperature (i.e. temperature when samples were
taken) using the CO2Sys Excel spreadsheet model for the inorganic
carbon system (Pierrot et al., 2006).
Gran titration: Alkalinity samples were measured by acidimetric
open-cell titration (Gran 1952). Alkalinity is inferred from
non-linear regression analysis from a titration curve between pH
values of 3.5 and 3.0.
CO2Sys calculated from alkalinity and pH: The CO2Sys model (Pierrot et
al., 2006) was used to calculate the partial pressure of carbon
dioxide in sampled river water from the measured alkalinity and pH.
Partial pressure of carbon dioxide was calculated for both bottle
temperature at time of lab analysis and in situ river water
temperature at the time of sample collection.
2. Data processing methods
This data product is designed to provide the provenance of final
tables in a pipeline format, to the degree that provenance is
available. Raw data files from instruments and manufacturer software
are available in the 01_Input.zip file. The coding used to process the
data is available in the 02_Protocol.zip file. In this case, final
processing was carried out with R scripts and R markdown files.
Incremental files created for the purpose of data processing are
available in the 03_Incremental.zip file. Ready-to-use analytical data
are available at the data package’s root level (on the dataset landing
page under the “Resources” section) and are described in the full
metadata.
2.1. Contents of 01_Input.zip
003_HoboCond_20200212_2017-OCT.hobo - Binary file for In Situ Hobo
electrical conductivity sensor serial number 20200212
Cond_20200211.csv - Comma delimited export of data for In Situ Hobo
electrical conductivity sensor serial number 20200211
Cond_20200211.hobo - Binary file for In Situ Hobo electrical
conductivity sensor serial number 20200211
Cond_20200212.csv - Comma delimited export of data for In Situ Hobo
electrical conductivity sensor serial number 20200212
Depth_20183501_111517.csv - Comma delimited export of data for In Situ
Hobo pressure sensor serial number 20183501
Depth_20183502_111517.csv - Comma delimited export of data for In Situ
Hobo pressure sensor serial number 20183502
SAMI_P87_151117.txt - Raw file for SAMI pH sensor serial number P87
SAMI_S5u_151117.txt - Raw file for SAMI CO2 sensor serial number S5u
SAMI_S13u_151117.txt - Raw file for SAMI pH sensor serial number S13u
SAMI_S53u_151117.txt - Raw file for SAMI CO2 sensor serial number S53u
2.2. Contents of 02_Protocol.zip
.RProfile - An R profile file with R code that establishes the
appropriate working directory for the R project used to generate this
data product.
00_a_Deployment)_notes.docx - Microsoft Word document for generating
the deployment notes PDF file
00_b_cleaning_dates.R - R script that generates the table and metadata
for the cleaning dates
01_a_galen_tables.Rmd - R markdown defining the quality assurance
visualizations, tables, and metadata for Galen site data
01_b_compile_galen.R - R script that compiles the Galen site R
markdown to a PDF document (03_Incremental.zip -
Notes_Galen_Processing.pdf)
02_a_racetrack_tables.Rmd - R markdown defining the quality assurance
visualizations, tables, and metadata for Racetrack site data
02_b_compile_racetrack.R - R script that compiles the Racetrack site R
markdown to a PDF document (03_Incremental.zip -
Notes_Racetrack_Processing.pdf)
10_a_edi_tempate.Rmd - R markdown defining the EDI metadata template
10_b_compile_edi.R - R script that compiles the EDI template R
markdown to a Microsoft Word document (EDITemplate.docx)
Protocol.Rproj - An RStudio project file provided for convenience in
working with the code generating this data product with the
appropriate working directory.
2.3. Contents of 03_Incremental.zip
2017_UCFR_Sensor_Deployment_Data_Stackplot_pCO2_pH_T.pdf – A
visualization generated for data quality assurance purposes. The three
plots include time on the abscissa with pH, Temperature, and pCO2 on
separate ordinate axes.
Data_2017_LTREB_Bottle_Data_For_QA.xlsx - Microsoft Excel file with
the original quality assurance data from grab samples compiled by Cory
Beatty
Data_2017_UCFR_Sensor_Deployment_QA.xlsx - Microsoft Excel file with
the original sensor data compiled by Cory Beatty
Notes_Deployment.pdf - Original deployment notes compiled by Cory
Beatty
Notes_Galen_Processing.pdf - Notes on generating data tables for Galen
site
Notes_Racetrack_Processing.pdf - Notes on generating data tables for
Racetrack site
3. References:
Gran, G. 1952. Determination of the equivalence point in
potentiometric titrations. Part II. Analyst 77: 661–671. doi:
10.1039/AN9527700661
Lai C.-Z., M. D. DeGrandpre, B. D. Wasser, T. A. Brandon, D. S.
Clucas, E. J. Jaqueth, Z. D. Benson, C. M. Beatty, and R. S. Spauldin.
2016. Spectrophotometric measurement of freshwater pH with purified
meta‐cresol purple and phenol red. Limnology and Oceanography: Methods
14(12) 864-873. doi: 10.1002/lom3.10137.
Pierrot, D. E. Lewis,and D. W. R. Wallace. 2006. MS Excel Program
Developed for CO2 System Calculations. ORNL/CDIAC-105a. Carbon Dioxide
Information Analysis Center, Oak Ridge National Laboratory, U.S.
Department of Energy, Oak Ridge, Tennessee. doi:
10.3334/CDIAC/otg.CO2SYS_XLS_CDIAC105a