uid=HFR,o=lter,dc=ecoinformatics,dc=org
all
public
read
doi:10.6073/pasta/b307cd3005dc90b5ff28abb7e74cf394
Hydrocarbon Concentrations at Harvard Forest EMS Tower 1992-2001
William
Munger
https://orcid.org/0000-0002-1042-8452
Steven
Wofsy
https://orcid.org/0000-0002-3133-2089
Allen
Goldstein
https://orcid.org/0000-0003-4014-4896
Researcher
Ben
Lee
Researcher
2023
English
Hydrocarbons are products of incomplete combustion and also emitted by vegetation. Hydrocarbons are important precursors for photochemical ozone formation. A system to quantify concentrations of several low-molecular weight hydrocarbons was installed at the EMS tower in the summer of 1992. The measurements were intended to help resolve questions about the potential reactivity in rural New England atmosphere and identify and quantify biogenic hydrocarbon emissions.
air pollution
hydrocarbons
organic carbon
LTER controlled vocabulary
primary production
inorganic nutrients
LTER core area
Harvard Forest
HFR
LTER
USA
HFR default
This dataset is released to the public under Creative Commons CC0 1.0 (No Rights Reserved). Please keep the dataset creators informed of any plans to use the dataset. Consultation with the original investigators is strongly encouraged. Publications and data products that make use of the dataset should include proper acknowledgement.
Creative Commons Zero v1.0 Universal
https://spdx.org/licenses/CC0-1.0.html
CC0-1.0
https://harvardforest.fas.harvard.edu/exist/apps/datasets/showData.html?id=hf145
Prospect Hill Tract (Harvard Forest). Coordinates based on WGS84 datum.
-72.171478
-72.171478
+42.537755
+42.537755
340
340
meter
1992
2001
complete
Information Manager
Harvard Forest
324 North Main Street
Petersham
MA
01366
USA
(978) 724-3302
hf-im@lists.fas.harvard.edu
Harvard Forest
324 North Main Street
Petersham
MA
01366
USA
(978) 724-3302
(978) 724-3595
https://harvardforest.fas.harvard.edu
Air was drawn continuously from two inlets (24 and 29 m). Samples for analysis were extracted from the inlet lines, and passed through glass cold traps at -20 C and Ascarite II (Thomas Scientific) traps to remove H2O, O3, and CO2. Samples were cryogenically preconcentrated on dual traps (40 ml min-1 of air for 10 minutes onto fused silica lined 1/16" OD stainless steel tube, Silcosteel), and injected into a gas chromatograph with dual Flame Ionization Detectors (Hewlett Packard 5890 series II). Chromatographic separation was accomplished using 30 meter PLOT GS-Alumina Megabore capillary columns (J+W Scientific). Every fifth pair of samples was taken from the same altitude (29 m) by switching a valve near the inlet of the 24 m sampling line in order to determine the NULL for the observed concentration gradient. The measurement system could operate continuously and unattended for more than two weeks, although data were normally downloaded at six day intervals. Concentrations for most hydrocarbons were determined using relative response referenced to an internal neohexane standard (Scott-Marrin, NIST traceable * 2%) added to every sample near the sample inlet by dynamic dilution. Response factors for isoprene were determined from dynamic dilution of isoprene standards (Scott-Marrin, NIST traceable * 2%) added to ambient air samples near the sample inlet periodically from May to November 1995.
The accuracy of the system was estimated to be better than * 18% for hexane and for hydrocarbons eluting before hexane, based on the cumulative uncertainty of the neohexane standard, measurements of standard addition flows, the integrity of individual compounds in the sampling and analysis process, and relative response factors. Accuracy of the isoprene measurements was estimated to be better than * 8% (more accurate than other species because the uncertainty of the relative response factor was eliminated). Measurement precision was approximately 3% at 1 ppbv, 5% at 0.5 ppbv, 10% at 0.2 ppbv, and 20% for concentrations less than 0.1 ppbv, as determined by the variance between measurements taken from the same level every fifth injection. The detection limit for these compounds was approximately 0.01 ppbv.
The analytical system was checked for contamination daily by running zero-air blanks. In addition, the Teflon sampling tubes were checked for contamination and memory effects by introducing zero-air at the sample inlets on top of the tower. No contamination or memory effects were detected for isoprene.
Concentration gradients of CO2 were measured simultaneously with the hydrocarbon gradients using a differential infrared gas analyzer (LICOR 6251), with air from 29 meters passed through the reference cell and air from 24 meters through the sample cell. Water vapor was removed from the air samples using nafion dryers, and the samples were assumed to be at a common temperature before analyzing for CO2. The NULL gradient was measured after every sampling period by filling both cells with air from 29 meters. Instrument gain was determined by standard addition of CO2 selectively to both the sample and reference air. The standard deviations of the zero gradient measurements were determined by comparing the NULL gradient measured every fifth sampling period (when hydrocarbon NULL gradients were determined) to the zero measurement directly following that period. The standard deviation in the zero measurements for CO2 (0.18 ppm) was much greater than 20 % of the mean midday gradients (-0.9 ppm CO2). Flux determinations were not attempted when observed gradients were very small, i.e. within 1 standard deviation of zero. The CO2 fluxes and gradients, and all the NMHC measurements are reported as mole fractions relative to dry air at a common temperature, avoiding the need for density corrections due to gradients in temperature or H2O.
Harvard Forest Long-Term Ecological Research
Harvard Forest
324 North Main Street
Petersham
MA
01366
USA
(978) 724-3302
(978) 724-3595
https://harvardforest.fas.harvard.edu
https://ror.org/059cpzx98
pointOfContact
The Harvard Forest Long-Term Ecological Research (LTER) program examines ecological dynamics in the New England region resulting from natural disturbances, environmental change, and human impacts.
National Science Foundation LTER grants: DEB-8811764, DEB-9411975, DEB-0080592, DEB-0620443, DEB-1237491, DEB-1832210.
hf145-01-hydrocarbon.csv
hydrocarbons
hf145-01-hydrocarbon.csv
5755001
def9bd79e1b0b845978e0de4e44e01a6
1
\r\n
column
,
https://harvardforest.fas.harvard.edu/data/p14/hf145/hf145-01-hydrocarbon.csv
year
year
YYYY
doy
day of year
nominalDay
0.001
real
NA
missing value
ethane
concentration of ethane in parts per billion by volume (ppbv)
dimensionless
0.00001
real
NA
missing value
ethene
concentration of ethene in parts per billion by volume (ppbv)
dimensionless
0.00001
real
NA
missing value
propane
concentration of propane in parts per billion by volume (ppbv)
dimensionless
0.00001
real
NA
missing value
propene
concentration of propene in parts per billion by volume (ppbv)
dimensionless
0.00001
real
NA
missing value
isobutane
concentration of isobutane in parts per billion by volume (ppbv)
dimensionless
0.00001
real
NA
missing value
butane
concentration of butane in parts per billion by volume (ppbv)
dimensionless
0.00001
real
NA
missing value
acetylene
concentration of acetylene in parts per billion by volume (ppbv)
dimensionless
0.00001
real
NA
missing value
butene
concentration of 1-butene in parts per billion by volume (ppbv)
dimensionless
0.00001
real
NA
missing value
cyclopentane
concentration of cyclopentane in parts per billion by volume (ppbv)
dimensionless
0.00001
real
NA
missing value
methylbutane
concentration of 2-methylbutane in parts per billion by volume (ppbv)
dimensionless
0.00001
real
NA
missing value
pentane
concentration of pentane in parts per billion by volume (ppbv)
dimensionless
0.00001
real
NA
missing value
butadiene
concentration of 1;3-butadiene in parts per billion by volume (ppbv)
dimensionless
0.00001
real
NA
missing value
propyne
concentration of propyne in parts per billion by volume (ppbv)
dimensionless
0.00001
real
NA
missing value
methyl.1butene
concentration of 3-methyl-1-butene in parts per billion by volume (ppbv)
dimensionless
0.00001
real
NA
missing value
pentene
concentration of t-2-pentene in parts per billion by volume (ppbv)
dimensionless
0.00001
real
NA
missing value
methyl.2butene
concentration of 2-methyl-2-butene in parts per billion by volume (ppbv)
dimensionless
0.00001
real
NA
missing value
cyclohexane
concentration of cyclohexane in parts per billion by volume (ppbv)
dimensionless
0.00001
real
NA
missing value
methylcyclopentane
concentration of methylcyclopentane in parts per billion by volume (ppbv)
dimensionless
0.00001
real
NA
missing value
hexane
concentration of hexane in parts per billion by volume (ppbv)
dimensionless
0.00001
real
NA
missing value
isoprene
concentration of isoprene in parts per billion by volume (ppbv)
dimensionless
0.00001
real
NA
missing value
52155
hf145-02-isoprene.csv
isoprene
hf145-02-isoprene.csv
68420
c6340ce1fbc81a6c373a7c30bf01dd42
1
\r\n
column
,
https://harvardforest.fas.harvard.edu/data/p14/hf145/hf145-02-isoprene.csv
year
year
YYYY
doy
day of year
nominalDay
0.001
real
NA
missing value
f.isop
isoprene flux
micromolePerMeterSquaredPerHour
0.01
real
NA
missing value
3871
atmosphere
long-term measurement
2
https://atmos.seas.harvard.edu/
https://harvardforest.fas.harvard.edu/exist/apps/datasets/showData.html?id=hf004
https://harvardforest.fas.harvard.edu/exist/apps/datasets/showData.html?id=hf066
https://harvardforest.fas.harvard.edu/exist/apps/datasets/showData.html?id=hf067
https://harvardforest.fas.harvard.edu/exist/apps/datasets/showData.html?id=hf060
micromolePerMeterSquaredPerHour