Stream chemistry and quality control data for watersheds 2 and 7 (starting 1972) at Coweeta Hydrologic Lab, North Carolina

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Entity_and_Attribute_Information:

Overview_Description:

Entity_and_Attribute_Overview:

Below you will find a list and description of the files included in this data publication.

ABBREVIATIONS USED

WS = watershed
QC = quality control
NA = not applicable
n.a. = not available - the instrument the analyte was measured on could not discern the peak from noise.
avg = average
abs = absolute
mdl = method detection limit
%RSD = percent relative deviation
std dev = standard deviation

Cl = chloride
K = potassium
pH = Hydrogen ion potential
SO₄ = Sulfate
Na = sodium
NO₃₋N = nitrate expressed as nitrogen
Ca = calcium
NH₄₋N = ammonia expressed as nitrogen
o-PO₄ = ortho phosphate
Mg = magnesium
CaCO₃ = calcium carbonate = ANC - acid neutralizing capacity - bicarbonate calculated as CaCO₃
SiO₂ = silica

g = gram
ha = hectare
L = liter
mm = millimeter
mg = milligram


DATA FILES

These files contain chemistry and quality control data from watershed 2 (WS02) and watershed 7 (WS07) for the period of 1972-2017. Data are given in weekly concentration and monthly ion export. Data are provided in two formats: 1) Microsoft Excel Open XML spreadsheet file (\Data\XLSX\Coweeta_streamchem_and_QC.xlsx) with 7 worksheets and 2) each worksheet is also provided as a comma-delimited ASCII text file (\Data\CSV\*.csv). Below is a description of each worksheet/CSV file.


WORKSHEET 1 (Read_me):
Summary information about data files including a description of abbreviations used as well as references.


WORKSHEETS 2, 3 (WS02_ion_export_gram_per_ha, WS07_ion_export_gram_per_ha:
Monthly ion export data from 1972-2017 for WS02 and WS07.

Variables include:

period ending = date of measurement (year-month-day)

flow samples = number of days data recorded in the month

runoff (mm) = daily flow in mm

monthly ion exports are provided in grams per hectare: pH, NO₃₋N, NH₄₋N, o-PO₄, Cl, K, Na, Ca, Mg, SO₄, SiO₂, CaCO₃


WORKSHEETS 3, 4 (QC_weekly, QC_monthly):
Weekly data with quality control (QC) data gives the quarterly QC data (%error, %RSD and mdl) associated with the analysis performed on samples collected weekly. The QC data are obtained using certified samples containing the analyte of interest. The monthly spreadsheet has the same QC data but for the convenience of the user - monthly dates are given. There was no need to average results.

Variables include:

month = month

day = day

year = year

Instrument pH = The instrument quantifying pH was performed on. There were several different instruments for pH during the period of record beginning in 1972.

Instrument anions = anions = o-PO₄, NO₃, SO₄, Cl = The instrument quantifying anions was performed on. There were several different instruments for the analysis during the period of record beginning in 1972.

Instrument NH₄, SiO₂ = The instrument quantifying NH₄ and SiO₂ was performed on. There were several different instruments for the analysis during the period of record beginning in 1972.

Instrument cations = cations = K, Na, Ca, Mg = The instrument quantifying cations was performed on. There were several different instruments for the analysis during the record of time beginning in 1972.

pH QC %error = Deleted absolute on worksheet. Note: Very little QC data was available for pH.

For the ion exports (pH, NH₄, SiO₂, Ca, K, Mg, Na, Cl, NO₃, o-PO₄, SO₄) the following variables are included:

QC %error = How close the mean of observed values is to the actual value. Using certified samples for each analyte (o-PO₄, NO₃, SO₄, Cl, K, Na, Ca, Mg, NH₄, SiO₂) a percent error is calculated: ((true value-mean of observed values)/true value) x 100.

QC %RSD = % relative standard deviation = Precision - How reproducible the observed value is. Using certified samples for each analyte (o-PO₄, NO₃, SO₄, Cl, K, Na, Ca, Mg, NH₄, SiO₂) the %RSD is calculated: (standard deviation of observed values/mean of observed values) x 100. Note: no %RSD data for pH.

mdl mg/L = method detection limit = The minimum concentration of a substance that can be measured and reported with 99% confidence that the analyte concentration is greater than zero (USEPA 2016). Using certified samples for each analyte (pH, o-PO₄, NO₃, SO₄, Cl, K, Na, Ca, Mg, NH₄, SiO₂) the mdl is calculated: standard deviation of observed values times student t for n-1 at 99% confidence level. n=number of samples


WORKSHEETS 6, 7 (WS02_weekly_with_QC, WS07_weekly_with_QC):
Weekly stream chemistry concentrations in mg/L (pH has not been converted to mg/L, the units are in hydrogen ion potential). QC values of %error, %RSD and mdl are given with each ion excluding pH and CaCO₃. No QC values were recorded for CaCO₃ and very few values for pH.

Variables include:

month = month

day = day

year = year

Instrument pH = The instrument quantifying pH was performed on. There were several different instruments for pH during the period of record beginning in 1972.

Instrument anions = anions = o-PO₄, NO₃, SO₄, Cl = The instrument quantifying anions was performed on. There were several different instruments for the analysis during the period of record beginning in 1972.

Instrument NH₄, SiO₂ = The instrument quantifying NH₄ and SiO₂ was performed on. There were several different instruments for the analysis during the period of record beginning in 1972.

Instrument cations = cations = K, Na, Ca, Mg = The instrument quantifying cations was performed on. There were several different instruments for the analysis during the period of record beginning in 1972.

head = height of water (feet) in weir pond above weir blade

pH = hydrogen ion potential

CaCO₃ mg/L = The acid neutralizing capacity of bicarbonate given as CaCO₃.

For all other ion exports (pH, NH₄, SiO₂, Ca, K, Mg, Na, Cl, NO₃, o-PO₄, SO₄) the following variables are included:

QC %error = How close the mean of observed values is to the actual value. Using certified samples for each analyte (pH, o-PO₄, NO₃, SO₄, Cl, K, Na, Ca, Mg, NH₄, SiO₂) a percent error is calculated: ((true value-mean of observed values)/true value) x 100.

QC %RSD = Precision - How reproducible the observed value is. % relative standard deviation = Using certified samples for each analyte (o-PO₄, NO₃, SO₄, Cl, K, Na, Ca, Mg, NH₄, SiO₂) the %RSD is calculated: (standard deviation of observed values/mean of observed values) x 100. Note: no %RSD data for pH.

mdl mg/L = method detection limit = The minimum concentration of a substance that can be measured and reported with 99% confidence that the analyte concentration is greater than zero (USEPA 2016). Using certified samples for each analyte (pH, o-PO₄, NO₃, SO₄, Cl, K, Na, Ca, Mg, NH₄, SiO₂) the mdl is calculated: standard deviation of observed values times student t for n-1 at 99% confidence level. n=number of samples



Note: QC values for HCO₃ as CaCO₃ are not available. The QA/QC program did not include QC samples for this. Beginning in 2018 % ion balance difference was calculated and found to be less than 10%. See section 4 in Sullivan et al. (2012).

Entity_and_Attribute_Detail_Citation:

Swank, Wayne T.; Knoepp, Jennifer D.; Vose, James M.; Laseter, Stephanie N.; Webster, Jackson, R. 2014. Response and recovery of water yield and timing, stream sediment, abiotic parameters, and stream chemistry following logging. In: Swank, Wayne T.; Webster, Jackson R., comps., eds. Long-term response of a forest watershed ecosystem. Clearcutting in the southern Appalachian. Oxford University Press: 36-56. https://www.fs.usda.gov/treesearch/pubs/45945

Brown, Cindi L.; Miniat, Chelcy F.; Knoepp, Jennifer D. 2021. Investigating the effect of lab bias on long-term stream chemistry data. Hydrology Research. 52(4): 864-875. https://doi.org/10.2166/nh.2021.164

U.S. Department of Agriculture Forest Service [USDA FS], Coweeta Hydrologic Laboratory. 2021 (revised). Procedures for Chemical Analysis. 281 p. Unpublished manual. On file with: Cindi Brown, Analytical Lab Manager, USDA Forest Service, Southern Research Station, Coweeta Hydrologic Laboratory, 3160 Coweeta Lab Road, Otto, NC 28763. Available online at: https://www.srs.fs.usda.gov/coweeta/tools-and-data/ (also included in data publication download: \Supplements\wetlab-cookbook_revised-2021-08-04.pdf)

U.S. Environmental Protection Agency [USEPA]. 2016. Definition and Procedure for the Determination of the Method Detection Limit, Revision 2. EPA 821-R-16-006. Washington, D.C., US EPA Office of Water, 6 p. EPA 600/4-79-020. Office of Research and Development Washington, DC 20460, 491 p.

Sullivan, T.J.; Herlihy, A.T.; Lawrence, & G.B.; Webb, J.R. (eds.) 2012 USDA Forest Service national protocols for sampling air pollution- sensitive waters. Gen. Tech. Rep. RMRS-GTR-278WWW. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 334 p. https://doi.org/10.2737/RMRS-GTR-278

Metadata_Reference_Information:

Metadata_Date: 20210920

Metadata_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: USDA Forest Service, Southern Research Station, Coweeta Hydrologic Laboratory

Contact_Person: Andrew C. Oishi (Chris)

Contact_Position: Team Leader

Contact_Address:

Address_Type: mailing and physical

Address: 3160 Coweeta Lab Road

City: Otto

State_or_Province: NC

Postal_Code: 28763

Country: USA

Contact_Voice_Telephone: 828-524-2128

Contact_Electronic_Mail_Address: andrew.c.oishi@usda.gov

Metadata_Standard_Name: FGDC Biological Data Profile of the Content Standard for Digital Geospatial Metadata

Metadata_Standard_Version: FGDC-STD-001.1-1999