Samples collected by the National Center for Atmospheric Research (NCAR) using the multiple-filter sampler on the U-2 were analyzed. The sampler is capable of exposing a number of 110 mm filters in sequence to ram air flow. Two types of filters, IPC cellulose and polystrene, were used, both of which have high blank levels for the trace elements determined. The levels of most trace elements in the stratosphere are so low under normal circumstances that none can be seen. Results from the eruption of Mt. St. Helens, a mystery cloud (probably volcanic in origin) in 1982, and the El Chichonal eruption in 1983 are discussed. To improve the collection of particles for chemical analysis, a new sampling system was developed for use on the U-2. The sampler consisted of an electrostatic collection of particles between 1 and 0.001 micron diameter dierectly onto electron microscopic grids, followed by a thermal precipitation for the smaller particles. The system was built and tested in the laboratory, but never flown on the U-2

Zoller, W. H.

English

NASA Technical Reports Server

Final Report NASA Contract NAG2-28
(NASA-CR-1769,01). VOLC1NIC IMPACT ON N86-31T16
STRAIOSPHERIC AEEOEOI. CHEMISl 'BY .Final .,
Beport,»ar.v19-8Q - Dec. ,19:83 (Haryland . .
Dniv.) 16 p . CSCL; 13B Onclas
63/^5 43027
VOLCANIC IMPACT ON STRATOSPHERIC AEROSOL CHEMISTRY
William H. Zoller
Department of Chemistry
University of Maryland
College Park, Maryland 20742
Final Report Covering the Period March 1980 to December 1983
https://ntrs.nasa.gov/search.jsp?R=19860021644 2020-03-20T13:21:23+00:00Z
.•4 —
A. Project Summary
This project was initiated as a supplemental program to analyze filter
samples collected by the National Center for Atmospheric Research (NCAR) group
using the multiple-filter sampler on the U-2. Al Lazrus and Bruce Gandrud of
NCAR designed and built the sampler which was capable of exposing a number of
110-mm filters in sequence to ram air flow. Two types of filters, IPC cellu-
lose and polystyrene, were used throughout this study, both of which had high
blank levels for the trace elements determined. The levels of most trace ele-
ments in the stratosphere are so low under normal circumstances that none can
be seen. During periods of volcanic injection into the stratosphere the
levels of many elements are significantly higher and measurements of the ash
content can easily be made. Following the eruption of Mt. St. Helens, samples
collected in the stratosphere contained significant levels of ash that
appeared to be unfractionated during the eruption, as it had a composition
similar to that of the volcanic rocks and ash found around the mountain.
During 1982, a "mystery cloud" appeared in the stratosphere and samples
of this revealed that it was also of volcanic origin. Although the volcano
which produced this cloud was never identified, it was probably one of the In-
donesian volcanoes, which were erupting during this time period. Following
the El Chichonal eruption in 1983, several U-2 flights were made to sample the
stratospheric cloud. On one of these flights a polystyrene filter was ex-
posed, which showed the presence of large quantities of sulfur, but no other
elements in excess of the filter blanks.
To improve the collection of particles for chemical analysis, a new sam-
pling system was developed for use on the U-2. This sampler consisted of an
electrostatic collection of particles between 1- and 0.01-ym diameter directly
onto electron microscopic grids, followed by a thermal precipitation for the
1
smaller particles. The system was built and tested in the laboratory, but due
to the time scale for construction and the end of this project, the sampler
was never flown on the U-2.
B. Description of the Sampling System and Filters Used
The sampling system that was used for this study was designed and built
at NCAR by Bruce Gandrud and Al Lazrus (1). This system used ram flow to
bring air into the wing tank of the U-2 aircraft, where 110-ram filters can be
placed in the air stream to collect the particles. The primary use of the
system was to measure sulfate and other water-soluble ions found in strato-
spheric particulates. Our portion of the project involved the analysis of the
samples by instrumental neutron activation analysis (INAA) to investigate
trace element concentrations.
The two types of filters used had relatively high blank values for trace
elements. The cellulose IPC filters, which are normally used for stratospher-
ic sampling, are relatively free of water soluble ions, but contain very high
levels of trace elements. The polystyrene filter had lower blanks, but had
much lower flow rates and were, therefore, unacceptable. Table 1 gives a com-
parison of the flow rates of the two filter types in the U-2 along with those
for two much cleaner filter types, used on the ground at the South Pole for the
collection of atmospheric particles for chemical analysis. From this table it
is obvious that the IPC filters have almost a factor of ten higher flow rate
than the other filters used. The blank values for the four types of filters
discussed are shown in Table 2. From these data, it is easy to see that for
most elements shown, the blank values for the IPC filters are much higher than
those for any of the other filters. The low flow rates of the polystyrene
make them useless, as their blank levels are not low enough to compensate for
the low flow rate.
In Table 3, results are shown for calculations of the time required to
collect a sample equal in concentration to a blank filter using the flow rates
(Table 1), blank values (Table 2) and assuming a concentration of each element
in the air sample equal to that found at the South Pole (2). This calculation
can be used as a gauge of the chances of measuring elemental concentrations at
a relatively clean location. The South Pole is the cleanest location on the
earth's surface, and probably represents a maximum level for the stratosphere
when no volcanic injections have occurred. For the IPC filters the only ele-
ments that have a chance of being observed in the clean, unperturbed strato-
sphere are Br, As and Se. The polystyrene filters are even worse, with only
Br and Sb being equal to blank values with a sampling time of approximately
one day. The Nuclepore filters likewise are not very good, and the Fluoropore
filters appear as the best possibility to obtain data on low stratospheric
concentrations of trace elements. These filters must be pumped as they creat
a large pressure drop across them when used. We proposed to contruct a sam-
pler to use these filters, but due to size constraints and cost, a pumped
system of sufficient capacity could not be designed and we chose to develop a
sampling system for single particle measurements which allow one to drasti-
cally reduce the blank values. During the term of this project a total of
approximately 80 filters and blanks were analyzed for nearly 35 elements and
sulfur wasn't the only element routinely observed over blank levels. During
periods of volcanic activity many other elements were also observed on the
filters as indicated in the reprints enclosed.
Because of the high blank levels in filters available to us as piggy back
experimenters, we could obtain useful information only on samples collected by
the U-2 during volcanic events in the stratosphere. Another area of work that
was successful was the measurement of radioactivity on the filters. Gamma-ray
measurements of Be and fission products from Chinese nuclear weapon tests
were done on all samples collected by the U-2.
C. Studies of Mt. St. Helens Stratospheric Plume (1980)
Samples of ash and particles were collected by the NASA U-2 aircraft on
May 19, 1980 following the eruption of Mt. St. Helens. These samples were
analyzed by INAA for 35 elements. The results published in Science (3) showed
that the chemical composition of particles in the stratospheric plume was very
similar to that of ash that fell out near the volcano and the rocks that make
up the volcano. Apparently very little chemical fractionation occurred during
the eruption, as the primary ash cloud in the stratosphere was produced by a
phreatic explosion. Later sampling of the plume during more quiescent phases
showed that the chemistry of the plume reflected the enrichment of many ele-
ments as volatile halide compounds. This enrichment process was not important
in the earlier explosion that reached the stratosphere as evidenced by the
stratospheric data (see Sect. J), but was very significant for low level tro-
pospheric injection.
D. Studies of the Mystery Cloud (1982)
During the Spring of 1982, a cloud was observed in the stratosphere by
Lidar measurements at Mauna Loa in Hawaii and at Langley, Virginia. The U-2
aircraft was used to sample the cloud on May 7, 1982, and the filters obtained
were analyzed by neutron activation analysis. Four filter samples were found
to have elemental concentrations in excess of the filter blanks. Although the
concentrations observed were not very high, they did show evidence of a com-
ponent with a composition similar to crustal dust and a number of other ele-
ments which were enriched relative to crustal dust. In Fig. 1, the logarithm
of the enrichment factor (EF) for one of the samples is shown. The EF is de-
fined as:
sample
(X/Al)crust
where X refers to the concentration of an element which is normalized to the
Al concentration and then to crustal dust, in this case Taylor's crustal abun-
dance data (4). The elements Se, Br, Cu, Cr, W, Zn and As are always found
enriched in volcanic plumes , so their appearance here would be indicative of a
volcanic source for the cloud. The high levels of I, Hf and Nd are suspicious
and are believed to be contamination or are related to rather unique chemistry
of the volcanic system and source area.
E. Stratospheric Radioactivity
During the initial phase of this work, measurements of radioactivity were
conducted on the U-2 filter samples. In general, the only radioisotope ob-
served was ^ Be, due to the detection technique used, y-ray spectroscopy. The
spectrum of each sample was taken on a Ge(Li) y-ray detector for several hours
prior to analysis by INAA. On all of the stratospheric samples , 'Be could be
easily measured and on a set of samples collected in November and December of
1980, large concentrations of fission products. were also observed.
An example of the normal ^Be and sulfate data are shown in Figs. 2 and 3.
Figure 2a shows the sulfate concentration versus altitude for the Poker Flat
flight series in July of 1979. The sulfate concentrations appear to peak at
an altitude between 15 and 16 km. Figure 2b shows the ?Be data for the same
four flights. The concentration of the peaks at an altitude of about 20 km.
The ratio of sulfur to ?Be versus altitude is plotted in Fig. 3 and, as can be
seen, the ratio is highest for the low altitude samples, which will be admix-
ing down into the troposphere.
The fission product data are contained in the reprint enclosed (Sect. J).
Briefly, we observed large quantitites of the fission products
141Ce, 144Ce, 103Ru, K^Ru, 131I and 137Cs during the flight series in July of
1981. By comparing the ratios of these isotopes it was possible to calculate
the detonation data of the weapon as October 16 ±4 days, which corresponds
well with the known date.
F. References
1, B. W. Gandrud, E. D. Lambdin, H. D. Johnson and A. L. Lazrus, in
preparation (1981).
2, W. R. Maenhaut, W. H. Zoller, R. A. Duce and G. L. Hoffman, Concentration
and Size Distribution of Particulate Trace Elements in the South Polar
Atmosphere, J. Geophys. Res. JB4, 2421-2431 (1979).
3, T. Vossler, D. L. Anderson, N. K. Aras, J. M. Phelan and w. h. Zoller,
Trace Element Composition of the Mount St. Helens Plume: Stratopsheric
Samples from the 18 May Eruption, Science 21, 827-830 (1981).
4, S. R. Taylor, Trace Element Abundance and the Chondritic Earth Model,
Geochim. Cosmochim. Acta ^ 8_, 1989-1998 (1964).
G. Talks (speaker underlined)
1, W. H. Zoller, "The Eruption of Mt. St. Helens, 1980", Earth Sciences
Division, National Science Foundation, Washington, D.C., July, 1980.
2, W. H. Zoller, T. Vossler and N. K. Aras, "Trace Element Analysis of the
St. Helens Plumes", Mt. St. Helens Volcano Workshop, NASA Ames
Laboratory, Moffett Field, CA, July, 1980.
3, N. K. Aras, D. A. Anderson, M. W. Johnson and W. H. Zoller, "The Use of
'Be as a Tracer of Stratospheric Sulfate in Remote Areas", ACS National
Meeting, Las Vegas, NV, August, 1980.
4, W. H. Zoller, Aerosol Chemistry of the Mt. St. Helens Plume", Invited
Talk, Tenth Int. Laser Radar Conference, Silver Spring, MD, Oct., 1980.
5, W. H. Zoller, "The Chemistry of Atmospheric Aerosols and the Effects of
Volcanism", Instituut voor Nucleaire Wetenschappen Ruksuniversiteit,
Ghent, Belgium, Oct., 1980.
6, W. H. Zoller, "The Eruption of Mt. St. Helens and the Effects on
Atmospheric Chemistry in Remote Areas", Institut fur Meteorologie,
Johannes Gutenberg Universitat and Max Plank Institute for Chemistry,
Mainz, West Germany, Oct., 1980.
7, T. Vossler, N. K. Aras, D. L. Anderson and W. H. Zoller, "Trace Element
Composition of Stratospheric Samples from the Plume of the Mt. St.
Helens Volcano", 15th ACS Middle Atlantic Regional Meeting, Washington,
D.C., January 1981.
8. W. H. Zoller, "Chemists and Volcanoes: Mt. St. Helens - A Case Study",
Keynote Address, Education Awards Luncheon, 15th ACS Middle Atlantic
Regional Meeting, Washington, D.C., January 1981.
9. W. H. Zoller, "The 1980 Eruption of Mt. St. Helens - Chemistry and
Atmospheric Implications", Central Penna. Section, ACS, Lock Haven, PA,
March 1981.
10. W. H. Zoller, "The 1980 Eruption of Mt. St. Helens - Chemistry and
Atmospheric Implications", Corning Section, ACS, Corning, NY, March
1981.
11. W. H. Zoller, "The Chemistry of Volcanic Eruptions", Chemistry
Department, State University of New York, Binghamton, NY, March 1981.
12. W. H. Zoller, "The Chemistry of Volcanic Plumes and the Effects of the
Eruption of Mt. St. Helens Volcano", Binghamton Section, ACS,
Binghamton, NY, March, 1981.
13. W. H. Zoller, "The Chemistry of Volcanic Plumes and the Eruption of Mt.
St. Helens", Norwich Section, ACS, Norwich, NY, March 1981.
14. W. H. Zoller, "The 1980 Eruption of Mt. St. Helens - Chemistry and
Atmospheric Implications", Syracuse Section, ACS, Oswego, NY, March,
1981.
15. W. H. Zoller, "The Impact of Volcanic Emissions on Atmospheric
Chemistry: The Eruption of Mt. St. Helens", Maryland Section, ACS,
March, 1981.
16. W. H. Zoller, "The Impact of Volcanic Emissions of Mt. St. Helens",
North Jersey Section ACS, Drew University, Madison, NJ, May, 1981.
17. W. H. Zoller, "The Impact of Volcanic Emissions of Mt. St. Helens",
Western Maryland Section ACS, Cumberland, MD, May, 1981.
18. W. H. Zoller, "The Work Done by the University of Maryland Research
Group on Mt. St. Helens Volcano", Nuclear Chemistry Division, Lawrence
Livermore National Laboratory, LLvermore, CA, May, 1981.
19. D. L. Anderson, J. M. Phelan, T. Vossler and W. H. Zoller,
Neutron-Capture Prompt Gamma-Ray Analysis of Stratospheric and
Groundfall Ash Following the Mt. St. Helens Eruption of May 18, 1980,
6th Int. Modern Trends in Activation Analysis Conf., Toronto, Canada,
June, 1981.
20. W. H. Zoller, Chemistry of Volcanic Emission - Mt. St. Helens, Invited
Feature Talk, 37th ACS Fall Scientific Meeting, Midland, MI, Nov. 1981.
21. W. H. Zoller, Problems of Sampling Volcanic Emissions: Mt. St. Helens,
American Meteorological Society, Omaha-Offutt Chapter, Omaha, NB, March,
1982.
22. W. H. Zoller, The 1980 Eruption of Mt. St. Helens: Chemistry and
Atmospheric Impact, Upper Peninsula Section, ACS, Michigan Technical
University, Houghton, MI, March 1982.
23. W. H. Zoller, The Chemistry of Volcanic Emissions: The Mt. St. Helens
Eruption, Geology Dept., Western Michigan University, Kalamazoo, MI,
March 1982.
24. W. H. Zoller, The 1980 Eruption of Mt. St. Helens, Western Michigan
Section, ACS, Grand Rapids Junior College, Grand Rapids, MI, March
1982.
25. W. H. Zoller, The 1980 Eruption of Mt. St. Helens: Chemistry and
Atmospheric Impact, St. Joseph Valley Section, ACS, Goshen College,
Goshen, IN, March 1982.
26. W. H. Zoller, The 1980 Eruption of Mount St. Helens Volcano, Chemistry
Department, University of Missouri, Columbia, MO, Sept. 1982.
27. W. H. Zoller, The 1980 Eruption of Mount St. Helens Volcano, ACS, Kansas
City Section, Kansas City, MO, Sept. 1982.
28. W. H. Zoller, The 1980 Eruption of Mount St. Helens Volcano, Department
of Chemistry, Quincy College, Quincy, IL; ACS, Quincy-Keokuk Section,
Quincy, IL, Oct. 1982.
29. W. H. Zoller, The Chemistry of Volcanic Emission: Mt. St. Helens,
Department of Chemistry, University of Missouri, Rolla, MO, Oct. 1982.
30. W. H. Zoller, The Chemistry of Volcanic Emission: Mt. St. Helens,
Department of Chemistry, University of Missouri, Springfield, MO, Oct.
1982.
H. Publications
1. T. Vossler, D. L. Anderson, N. K. Aras, J. M. Phelan and W. H. Zoller,
Trace Element Composition of the Mt. St. Helens Plume: Stratospheric
Samples from the May 18th Eruption, Science 208, 827-830 (1981).
2. N. K. Aras, J. R. Parrington and W. H. Zoller, The Measurement of Nuclear
Fallout from the October 1980 Chinese Nuclear Tests at Mauna Loa
Laboratory and High Altitude Samples, Turkish J. of Nucl. Sci. ^, 87-99
(1982).
3. W. H. Zoller, D. L. Anderson, M. P. Failey, J. L. Moyers and B. W. Mosher,
Nuclear Activation Analysis Methods and the Evaluation of Volcanic
Deposits and Emissions, in Proc. of the 4th Int. Conf. on Nuclear Methods
in Environmental and Energy Research, Univ. of Mo., Columbia, Apr. 1980,
J. R. Vogt, ed., CONF 800433, pp. 96-105.
Table 1
Flow Rates for Filters (11 cm diam)
Filter Type Flow Rate
L/m L/cm^-hr
Conditions
IPC 1,400 880
Polystyrene 150 95
Nuclepore (0.4 (vim) 100 610
Fluoropore (1 um) 300 190
ram air (U-2)
ram air (U-2)
pumped (MLO - South Pole)
pumped (MLQ - South Pole)
10
Table 2
Comparative Filter Blanks (ng/cm^ )
Element
Na
Al
Mn
Fe
Co
Element
Cl
Br
As (pg)
Se (pg)
In (pg)
Sb (pg)
IPC
208
120
4.5
220
0.17
IPC
460
1.2
30
<40
<
164
Polystyrene
20
34
1.0
42
0.031
Polystyrene
98
6
80
70
2.1
1,400
Nuclepore
1.4
2.8
0.047-0.084
3.8-4.2
0.0093-0.0095
Nuclepore
40
1.0
14-73
5.3-23
<0.2
5.6-25
Fluoropore
3.1
7.8
0.050-0.260
4.2-14
0.030-0.050
Fluoropore
6.6
0.08
2.5-260
1.2-5.3
<0.2
18-21
11
Table 3
Sampling Time Required to Equal Blank Concentrationsa
Element
Na
Al
Mn
Fe
Co
Cl
Br
As
Se
In
Sb
1PC
72
170
380
400
390
200
0.52
4.8
7.3
<20
220
Polystyrene
64
440
790
710
660
400
24
120
120
420
18
Nuclepore
67
540
560
970
3,000
240
6.1
31
14
<60
100
Fluoropore
4.9
50
20
36
320
13
0.16
1.8
1.0
<20
110
aAssumes an atmospheric concentration equal to that found at the South Pole
(2).
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Volcanic impact on stratospheric aerosol chemistry

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