(5) Dropp, L. T., Akbrut, A. J., Tepoloenergetika, 7,63-8 (1972). (6) Boll, R. H., Ind. Chem. Fundam., 12,40-50 (1973). (7) Behie, S. W., Beeckmans, J. M., Can. J . Chem. Eng., 51, 430
(1973). (8) Yung, S., Calvert, S.,Barbarika, H. F., “Venturi Scrubber Performance Model”, EPA 600/2-77-172,1977. (9) Calvert, S., Lundgren, D., Mementa, D. S., J.Air Pollut. Control Assoc., 22,529-32 (1972). (10) Nukiyama, S., Tanasawa, Y., in “Perry’s Chem. Eng. Handbook”, Perry and Chilton, Eds., 5th ed., McGraw-Hill,New York, N.Y., 1973.
(11) Hollands, K.G.T., Goel, K. C., Ind. Eng. Chem. Fundam., 14,
16-22 (1975).
(12) Brink, J. A., Contant, C. G., Ind. Eng. Chem., 50,1157 (1958). (13) Calvert, S., Yung, S., “Evaluation of Venturi Scrubber”, Final Rep. to EPA, Contract 68-02-1328,Task 6, Feb. 1975. (14) Raabe, 0 . G., J. Air Pollut. Control Assoc., 26,856-60 (1976).
Receiued for review June 30,1977. Accepted October 31,1977. Study supported by EPA under Contract No. 68-02-1328, Task No. 13.
NOTES
Ambient Air Hydrocarbon Concentrations in Florida William A. Lonneman*, Robert L. Seila, and Joseph J. Bufalini Environmental Sciences Research Laboratory, Research Triangle Park, N.C. 2771 1
In May of 1976 a three-day study was undertaken in St. Petersburgrnampa, the Everglades, and Miami areas to assess the importance of naturally emitted hydrocarbons to ozone production. Some samples were collected within inches of citrus trees in an effort t o observe the occurrence of natural terpene hydrocarbon emissions. Other samples were collected in remote areas to determine hydrocarbon composition and to investigate natural hydrocarbon contribution to the overall hydrocarbon burden. No significant natural hydrocarbon contribution was observed in any of the collected samples. The Clo terpene hydrocarbons were below our limit of detectability of 1 ppb carbon. The meterological conditions during this study were not conducive for the buildup of high hydrocarbon concentration, and low ozone levels were observed. The results suggest that natural hydrocarbon emissions are not as important as anthropogenic sources of hydrocarbon in the formation of ambient ozone. I t has been suggested that certain areas of Florida have high ambient ozone levels largely because of the high hydrocarbon emissions from citrus-type trees and perhaps through the decay of organic mat.ter in the large number of swamps in the area. Previous studies (1-3) have shown that several terpene-type hydrocarbons are contained in the volatile fraction of orange oil. These hydrocarbons include limonene, myrcene, alpha -pinene, and many others. One can therefore speculate that citrus trees may liberate many of these hydrocarbons into the environs during the growing process. Being olefinic in nature, these hydrocarbons are expected to have very high reactivity, i.e., in the presence of sunlight and oxides of nitrogen, the hydrocarbons rapidly oxidize and ozone is produced ( 4 ) . Therefore, many of the manifestations usually observed when auto exhaust is irradiated with sunlight can also be observed by the irradiation of naturally produced hydrocarbons in the presence of NO,. This three-day study was undertaken as a part of the Florida Ozone Transport Study ( 5 ) ,the purpose of which was to investigate occurrence, causes, and transport of high ambient ozone in Florida. If we consider the short duration of this effort, the results are taken to have a suggestive rather than conclusive nature. Experimental
Bag samples were collected in 2-mil Tedlar bags by means of a battery-operated Thomas pump. The internal parts of the pump consisted only of Teflon and stainless steel components,
thus minimizing pump contamination. Earlier laboratory studies have shown that the pump is inert in both emissions and adsorption of hydrocarbons up to Clo. A 10-L volume of sample air was collected usually over a 2-5-min time period. The Tedlar bags were always covered with aluminized Scotch Pak. This precaution was taken since the hydrocarbons would photooxidize in the bags when exposed to sunlight. The bag samples were shipped by commercial air freight to the Research Triangle Park, N.C., facility for detailed gas chromatographic hydrocarbon analyses. Detailed descriptions of the gas chromatograph (6) and the cryogenic concentration apparatus (7) systems are published elsewhere. Usually, a 0.5-1-L volume of sample is sufficient to obtain subpartper-billion carbon sensitivity for most components. A total of 24 grab bag samples was collected over a three-day sampling program of May 13,14, and 18.Eight samples were collected a t ground level sites, while 16 samples were collected from an aircraft a t 2000 ft during the ozone sampling program. Not all of the GC data from this study are presented in this report since for the most part the compositional details of the samples were quite similar.
Results and Discussion The detailed hydrocarbon results of some selected samples are shown in Table I. The data are separated into ground samples (G), aircraft samples (A), and one downtown Miami ground-level sample (D). The geographical locations a t which the bag samples were collected are shown in Figure 1. Samples G-2 and G-3 were collected in an orange grove near Dunedin, Fla. These samples were collected close to the citrus trees where ambient air dilution processes are minimal, and natural hydrocarbon concentrations are expected to be the greatest. Sample G-3 was collected a t a distance of approximately 10 f t from the citrus trees, while sample G-2 was collected within inches of the fruit trees. No significant changes were observed in the CI-Clo hydrocarbon distribution. In fact, the terpene hydrocarbons previously observed in orange oil (1-3) were not observed in either of the collected bag samples, even though these compounds would appear as separate peaks on our gas chromatographic column and our sensitivity is less than 1.0 ppb carbon (0.1 ppb compound). Since we did not observe any of the Cl0 terpenes in our bags, our concern was that these hydrocarbons could possibly be adsorbed on the pump or Tedlar bag surfaces. We excluded these possibilities when later laboratory studies performed a t low terpene concentrations (5-25 ppb carbon) showed no pump losses and excellent bag storage characteristics.
This article not subject to U.S. Copyright. Published 1978 American Chemical Society
Volume 12, Number 4, April 1978
459
fable I. Detailed Hydrocarbon Concentrations ppbC and Collection l i m e of Air Samples from Different Florida Locations Sample Compound
Ethane Ethylene Propane Acetylene lsobutane *6utane Propylene Isobutylene trans-2-Butene Unknown 1 cis-2-Butene 13-Butadiene lsopentane *Pentane 1-Pentene 2-Methyl- 1-butene trans-2-Pentene cis-2-Pentene Acetaldehyde a Cyclopentane isoprene 2-Methy lpentane 3-Methylpentane 4-Methyl-2-pentene *Hexane 1-Hexene trans-3-Hexene 2,4-Dimethylpentane Propionaldehyde Acetonea Cyclohexane 2-Methy lpentane 23-Dimethylpentane 3-Methylhexane 2,2,4-Trimethylpentane *Heptane Methylcyclohexane Toluene Unknown 2 Unknown 3 Nonane Unknown 4 Ethylbenzene pXylene mXylene Unknown 5 alpha-Pinene &Xylene Unknown 6 Isopropyl benzene *Decane Unknown 7 beta-Pinene n-Propylbenzene mEthyltoluene pEthyltoluene Unknown 8 1,3,5-Trimethylbenzene o-Ethyltoluene 1,2,4-Trimethylbenzene
+
+
480
Q.2 May 13 1200
2.9 3.6 3.1 4.3 2.7 7.5 1.o 1.2 1.o 0.9 0.4 9.0
3.3 0.4 0.4 0.0 0.0 21.4 5.5 3.2 2.3 0.0 2.2 0.0 0.0 2.4 0.9 6.7
0-3 May 13 1210
3.0 3.8 3.1 4.6 2.5 7.5 0.9 1.3 0.6 0.9 0.4 9.0 4.0 0.4
0.3 0.0 0.0 22.7 5.1
3.0 1.8 0.0 1.7 0.1
0.3
1.3 0.0 0.0 1.3 1.1 1.1 8.4 3.6 2.9 2.3 0.5 1.2 1.1
1.9 1.2 10.3 0.0 3.2 0.0 1.6 1.3 1.1 4.3 7.2 15.1 10.4 2.8 0.0 1.4 1.2
3.0
3.3
0.0 0.0 3.4 0.0 0.9 3.8 0.0 0.0 0.4 2.9
0.5 0.0 4.1 0.0 1.4 0.0 0.0 0.0 0.6 1.4
0.0 2.3 1.8 1.9
0.0 0.8 0.0 0.9
0.3
Environmental Science & Technology
0-6 May 14 1900
A-4 May 18 1000
A-5 May 18 1030
May 18 0800
1.9
2.3 0.6 0.3 1.1 0.0 0.0
2.8 3.9 5.9 9.0 6.8 22.5 1.9 0.0 19.1
5.7 10.5 19.5 11.3 5.5 16.4 0.0 2.6 2.2
0.0 0.9 22.9 8.7 0.6 0.6 0.0 0.0 160.2 1.8
0.0 0.0 22.3 10.2 0.7 0.0 1.8 2.1
4.5
2.7 1.4 6.0 1.2 0.0 2.0 2.0 0.0 2.7 2.6 0.0 1.2 4.3
6.5 4.0
