Table Of ContentStudies in Environmental Science 20
ATM 0s PH E R IC
POLLUTION 1982
Proceedings of the 15th International Colloquium, UNESCO Building, Paris, France,
May 4-7,1982
Organised by the lnstitut National de Recherche Chimique Appliquie, Vert-le-Petit,
France, in association with the Commission on Atmospheric Environment of the
International Union of Pure and Applied Chemistry (IUPAC), the World Health
Organization (WHO), the Gesellschaft fur Aerosolforschung (GAeF) and the
Fraunhofer Gesellschaft (FhG)
edited by
Michel M. Benarie
These papers have been published as a special issue of
The Science of the Total Environment, Volume 23, 1982
ELSEVIER SCIENTIFIC PUBLISHING COMPANY
Amsterdam - Oxford - New York 1982
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0 Elsevier Scientific Publishing Company, 1982
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V
PREFACE
Why a colloquium? In these times of an information explosion, of a
mushrooming number of scientific journals, and when we are at the threshold of
electronic publishing, why gather people together, at considerable expense and
loss of time for them, simply so that they nay listen to oral presentations?
I can put forward two reasons.
The first reason is derived from my view that the purpose of all scientific
communication is interaction. To interact means to spread one's own ideas,
results, etc., as widely as possible to gather in as many comments, criti-
cisms, novel points of view and, perhaps, applause as possible. If a measure
of the "strength of interaction" can be obtained from the number of references
to work done and published, then I can propose some conclusions I have obtained
from examining a sample of papers within the field of the atmospheric environ-
ment. In any paper, on average, the papers most frequently quoted are those of
the author himself, the so-called self-references. Second in frequency are
references to papers originating from the same laboratory, work group or
institute as the author. Then follow, with about the same frequency, references
to authors who co-participated within the previous 10 years at a colloquium or
other kind of meeting and references to papers that appeared in the same journal
as the author's paper is published.
Please do not smile at the frequency of self-references. They are not
evidence of authors' vanity. Nobody is nearer to the recent history of a very
specific topic, to a given train of thoughts, to the particular method of
investigation of a scientist, than the author himself. With this idea in mind,
it is clear that the above-mentioned order of frequencies of references, i.e.
self, group, co-participant, same journal, simply express the increasingly
larger sets of scientists who are involved with, understand, and are interested
in, the work that the author is currently doing. This order of reference
frequencies proves how effectively a colloquium enhances scientific interaction.
In our specific situation, when the Colloquium papers are at the same time a
special volume of The Science of the Total Environment, a well-known and
widely available journal in the. field, the diffusive interpenetration of ideas
is even more enhanced.
The second reason why people come to a colloquium is so that they can
follow or take part in the discussions, the remarks, and the questions which
follow each oral presentation. Unfortunately, the present volume, for the
convenience of the participants, had to be ready at the opening of the
Colloquium, and thus could not include the discussions held during the
Colloquium itself. Such discussions are nevertheless a very essential component
of any meeting. Every author left the podium enriched with some suggestion or,
at least, with the implicit judgement of a polite but sparse applause not
followed by any pertinent question - perhaps because his work or his manner of
presentation failed to arouse sufficient interest. No journal, no referee, no
editorial committee is able to act as such a multiheaded, effective, and quick
jury. Vox populi, vox Dei.
Why this colloquium? My starting point is once more the information
explosion. Every year new sub-specialities and sub-sub-specialities are born.
There are specific gatherings, not only for atmospheric modellers, but also
separately for urban, for meso-scale, for long-range, etc. modellers. Every
atmospheric pollutant, whether i t be sulphur, nitrogen, pesticides, or nitro-
samines, draws together its specialists somewhere. Aerosol science is branching
out into a dozen topics, each one with its annual, or even more frequent,
meeting .
Ours is a holistic approach. The divergences resulting from growing
specialization require increased efforts in synthesis. Our purpose is to draw
together individual scientists who are in danger of becoming cloistered within
their narrowly limited field. We wish to try and maintain links, develop a
common language, stress points of common interest, and further interaction
among the ever-widening branches of atmospheric environmental science. New
shoots nourish a tree, but they cannot support themselves in thin air without a
sustaining stem. At a time when science is looking with more and more accuracy
at less and less, we must also sustain the spirit of the whole. To fully
understand the parts of our subject we must occasionally try and look at the
whole in a spirit of comprehensiveness. Such an approach is the basis of the
scope of The Science of the Total Environment.
This holistic tendency notwithstanding, we are always receptive to new
extensions. Since its beginnings, air pollution science has been urban-
industrial/temperate-zone orientated. The problems were the most acute and
the most perceptible in this geographical context. Now, gradually, we are
becoming increasingly aware that arid and tropical regions also have their
problems. We are almost totally ignorant about wet-subtropical air chemistry.
The tropical agroindustry is an enormous, diffuse source of air pollutants.
Last, but not least, the problems of desert air have barely been touched.
Therefore, as first point on our programme this year, we included a session
dealing with the pollution problems of hot and desert regions, and we hope to
follow this topic up in a future Colloquium in more depth. The other topics
covered in the programme were:
w
- Atmospheric flow and dispersion; modeling.
- Health effects, industrial hygiene and the control of air pollution in
industry.
- Aerosols: their characterization, techniques of measurement.
- Aerosol physics.
- Air chemistry; wet and dry deposition of pollutants.
- Field results; monitoring and surveys.
This volume contains the accepted papers selected from the 80 that were
submitted to this 15th International Colloquium held in the Palais des C0ngrS.s
(Port Maillot) in Paris. The international character of the meeting is evident
from the origin of the papers received. They were contributed by scientists
from 22 countries.
Michel BENARIE
3
AIR POLLUTION IN TROPICAL AREAS
EUGENIO SANHUEZA, MABELL AFRICAN0 and JOHNNY ROMERO
I.V.I.C. Apartado 1827, Caracas, Venezuela
ABSTRACT
Air pollution problems in three different tropical areas are presented. The
levels of various atmospheric contaminants (i. e. SOi) indicate that the operation
of a large petroleum refinery affects a substantial portion of the island of
Curacao. A significant fraction of the suspended particles in Curacao are due to
non-traditional open source emissions aided by the predominantly high wind speeds.
Particulate emissions from the industrial complex in Guayana, Venezuela, noticeably
affect the sorrounding savannah. The constant direction of the Trade Winds is an
important factor in the high long-term average particulate levels down-wind of the
complex. A serious atmospheric contamination problem (i.e. TSP) exists in The
Valley of Caracas. The high emission, principally due to the circulation of vehicles,
exceed the average dispersion capacity of the atmosphere.
INTRODUCTION
Tropics is a term that has no well-defined meaning. It is generally agreed
that tropical areas are located between the 23.5 degree parallels. However, some
regions with tropical characteristics are found at latitudes greater than 23.5",
and some non-tropical areas are located closer to the Equator.
Nieuwolt (ref.1) suggests that certain climatic characteristics can be used to
establish the boundaries of tropical areas. Some of his criteria are:
i) the absence of a cold winter season
ii) a larger diurnal fluctuation in temperature than the yearly variation in the
daily mean temperature (in the mid-latitudes the inverse is true)
iii) sufficient rainfall to support agriculture without irrigation
It is usually considered improbable that the air in tropical areas can become
polluted to harmful levels. Petersen (ref.2) estimated that the air pollution
potential (inability of the atmosphere to disperse pollutants) of most tropical
regions is low. The 1972 Florida State Air Implementation Plan states "Because of
the general pattern of terrain and the trade wind circulation, meteorological condi-
tions that aggravate air pollution do not often occur at any place in Florida".
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More recently Ng'ang'a (ref.3) Concluded that in tropical regions "air pollution
may not become such a serious problem unless or until the rate of industrialization
is dramatically increased".
There are however a number of examples of pollution problems in the tropics.
Gerrish (ref.4) found that atmospheric conditions in "tropical" Florida could lead
to severe air pollution episodes. NOx (ref.5) and Pb (ref.6) levels measured in
Caracas exceed the air quality standards established for various countries.
This paper discuss various circumstances under which relatively large tropical
areas may experience air pollution problems.
THE ISLAND OF CURACAO
Curacao is a Caribbean island located at 12"North latitude, 56 Km from the
South American continent. It is 61.2 Km long, with a width that varies between
3.2 and 12.1 Km. The total area is 466.2 Km2. The terrain is relatively flat with
only a few low hills. The average annual meteorological conditions (1947 to 1978)
are: temperature 27.5"C, maximum temperature 30,8"C, minimum temperature 19.8"C,
rain 564.2 mm, wind direction 90°, wind speed 7.2 m/s, and wind stability 96.5%.
It is important to mention that the difference between the monthly average tempera-
ture of the coldest and the warmest month is only 2.5"C.
A three month diagnostic study was undertaken to make a preliminary assessment
of the island's air quality. Principal sources include a large oil refinery in
Shottegat Bay and a power plant (with a sea water desalinization plant). Fig. 1 is
a partial map of Curacao that shows the position of these sources and of the five
monitoring sites. Piscadera is a tourist complex with beaches, Wishi is a low-
income residential area, Buena Vista is a residential area, Blauw is presently
empty land but it has potential for touristic or residential development, Soltuna
is an experimental Agricultural Station. Figure 1 also includes a representative
wind rose for 1973. Based on the wind information, values measured in Soltuna are
considered representative of background levels.
Almost all of the important air quality parameters were monitored during the
diagnostic study. The level of total suspended particles represents the greatest
problem and will be discussed in detail, including the chemical composition. This
aspect is of interest to environmental scientists because of the potentially
hazardous nature of certain components and because the ch,emical composition can be
used to identify specific sources.
The combustion of residual fuel constitutes art important source of primary
sulfate (ref.7,8). Since both the refinery and power plant burn residual fuel with
2% or more S, SO; will be used to evaluate industrial emissions. Atmospheric lead
levels will be used to estimate the influence of vehicular traffic and C1- for the
sea salt contribution.
5
Fig. 1. Partial Map of Curacao
Table 1 summarizes the results of the TSP measurements, the size characteristics
and the SO;, Cl- and Pb content. The SO; values have been corrected for artifact
formation of sulfate in the fiber glass filter using the formula proposed by
Coutant (ref.9).
Table 1 shows that the concentrations of TSP, SO; and lead at the other four
stations are significantly higher than at the reference station, Soltuna. The
levels of TSP and SO; at Wishi are very high. The levels of C1- are very similar
at all five stations, showing the common sea salt spray origin.
The calculated enrichment factors (E.F.) for sulfate and Pb are:
Piscadera (201) > Blauw (126) > Buena Vista (103) > Wishi (87) and
EFsoi :
Wishi (4.2)> Buena Vista (2.05)> Blauw (1.5)> Piscadera (1.4)
EFpb :
The EF's were calculated using EF (i)=(X/TSP)i/(X/TSP)soltuna
Where X is the concentrations of SO; or Pb and i indicates the monitoring
stati on.
Based on the EF values and the data in Table 1, the following inferences can
be made:
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Piscadera: This station has the lowest levels of TSP, one of the highest absolute
values of sulfates and the largest E.F. for sulfates. The EF for lead indicates a
small vehicular traffic influence. Considering the high incidence of sulfates
associated with small particles (MMO < 1.Ovm) it can be concluded that this part of
the island is significantly affected by the refinery and power plant emissions.
TABLE 1
Total Suspended Particles, SO%, C1- and Pb in the Curacao Air
Site na TSP MMD <2.5pm >7.0pm so; ci- Pb
~ 1 m 3 vm % % vg/m3 vg/m3 w/m3
Piscadera 6 60.1 <1.0 ~ 7 5 - 19.0 8.43 0.054
Wishi 5 163.7 1.8 54.5 30.0 22.5 5.72 0.44
Buena Vista 5 68.8 1.7 58.7 20.3 11.2 6.53 0.089
B1 auw 8 68.6 2.7 47.3 26.0 13.7 4.29 0.065
Sol tuna 2 28.6 1.4 61.5 15 .O 0.05 5.51 0.018
a) number of samples
Wishi : This residential and commercial area is quite influenced by vehicular traffic
as shown by the high EF for lead. The highest absolute values for sulfates were
found here, demonstrating the influence of the refinery emissions. The extremely
high TSP levels, coupled with the large percentage of large particles indicate that
there must be an additional source of particles. Lincoln and Rubin (ref.10) suggest
that most of the particulate matter associated with vehicular traffic is due to
reentrainment of road dust rather than to particles emitted directly from the mobile
source. A large fraction of the suspended particles measured at Wishi must have
been produced by the circulation of vehicles aided by the high wind speeds observed
on the island (ref.11).
Buena Vista: As expected, some vehicular traffic influence is seen in this residen-
tial area. The refinery plume crosses this area very infrequently and the SO=
4
concentration is the lowest of the four stations.
Blauw: The high sulfate EF indicates the influence of the refinery emissions on
the TSP levels in Blauw. It is important to note that this station is more than
5 Km downwind of the refinery. The various unpaved roads in the vicinity of this
station are probably the source of the large particles observed there (Table 1).
There are strong indications that the health damage formerly attributed to SO;
is caused by acid particulate sulfate (ref.12). Community health studies (CHESS)
have demonstrated a substantial relationship between some types of morbidity and
sulfate levels in the 8-12 pg/m3 range (ref.13). In several places in California
with low atmospheric dispersion, the levels of SO; (1972-1973) varied between
5.7 and 21.8 pg/m3 (ref.14). In 1976 the average SO,= level for 43 Ontario sites
was 7.2 ug/m3 (ref.15). In Caracas, a contaminated tropical city, the yearly
average in 1977 was 5.6 ug/m3 (ref.16).
7
Taking this into consideration, one can conclude that a SO= contamination
4
problem exists in practically all the area downwind of the refinery to a distance
of greater than 5 Km. It is logical to suppose that other contaminants are
distributed in the same manner.
The presence of high wind speeds is usually considered a favorable meteorolo-
gical factor in air pollution problems (ref.3). However, a significant fraction
of the suspended particles in the atmosphere in Curacao are due to non-traditional
open source emissions (i .e. travel on paved and unpaved roads, wind erosion) aided
by the predominantly high wind speeds. Excluding from the analysis the days with
rain and those in which the predominantly wind direction deviated greatly from the
normal a reasonable correlation between the TSP levels and the wind speed was
observated.
THE GUAYANA INDUSTRIAL COMPLEX
Ciudad Guayana is a planned industrial city that was founded in 1961 to serve
as the urban nucleous of an industrial complex in the southeastern part of Venezuela
It includes one of the biggest single iron-steal plants in the world, a very large
aluminum complex, ferro alloy production plants, among other industries.
The main energy source for the industrial complex is an hydroelectric plant.
The second most important form of energy used is natural gas. As a result, the
atmospheric emissions associated with energy use are relatively low. However, the
atmospheric emissions generated by the industria processes are significant. A
recent emition inventory has found that 3.4 tons of particulate matter per hour
are emitted from the numerous industrial stacks ref .17).
It is important to point out that the industr a1 complex is located downwind of
the Ciudad Guayana urban development. The plumes disperse over currently undevelop-
ed areas that are important to the future growth of the region (exploitation of
the Orinoco Heavy Oil Belt). Mathematical dispersion models have been used to
estimate the contamination levels in undeveloped area attributed to the atmospheric
emissions from the industrial complex (ref.18).
The calculations indicate that during the day, particulate levels higher than
100 ug/m3 should only exist very close to the industrial complex. Neverthless,
during the hours with low irradiation the levels exactly downwind, exceed 100 pg/m3
over a large distance reaching a maximum of 400 pg/m3 14 Km from the sources, which
is maintained to a distance of 23 Km. Levels higher than 150 pg/m3 are obtained
over a downwind width of approximately 10 Km at distances of 12 to 19 Km.
Ciudad Guayana is located on a wide savannah. The Trade Winds dominate the wind
patterns. Around 90% of the time the wind direction fluctuates between E and NE.
Considering that the plume disperses preferentially over the same area and that
the night time dispersion (radiative inversion) is low, it is likely that the
