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CURRENT RESEARCH

Sources of Vanadium in Puerto Rican and San Francisco Bay Area Aerosols Christopher S. Martens,' Jerome J. Wesolowski,* Robert Kaifer, and Walter John3

Lawrence Livermore Laboratory, Livermore, Calif. 94550 Robert C. Harriss

Department of Oceanography, Florida State University, Tallahassee. Fla 32306

Atmospheric L7 sampled in the San Francisco Bay area appears to originate from both soil and combustion sources. V sampled in air flowing onto the eastern end of Puerto Rico can be associated with an Al-depleted soil source through comparisons of abundances of V, Al, Co, and Cr. Previous work (Martens and Harriss, 1973) has shown that these elements behave similarly during aerosol growth in Puerto Rican orographic clouds.

of Pittsburg station located less than 1 km from a utilities plant in a small business section of town; L, City of Livermore station located in a primarily residential area of a small valley immediately to the east of the hills bordering San Francisco Bay; R, City of Richmond station located in a residential area across the Bay from the city of San Francisco; RC, Redwood City station located in the center of a light industrial area near the U.S. 101 freeway on the

Considerable information on the abundance and particle size distribution of V has been gathered during extensive multielement investigations of the atmospheres of Puerto Rico and the San Francisco Bay area (Martens, 1972). Previous surveys of urban, industrial. and more remote locations have indicated several sources of atmospheric Y including: soil (Rahn et al., 1971; John et al., 1973): oil refining and chemical manufacturing (Sifong, 1970); and fuel oil combustion (Nifong. 1970; Zoller and Gordon, 1970; Brar et al., 1970). Our present objective is to investigate the origins of V by comparing the abundances and particle size distributions of V to that of the other elements found in the atmospheres of the San Francisco Bay and Puerto Rico areas.

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Sampling and Analysis

Atmospheric sampling was carried out at nine stations in the San Francisco Bay area (Figure 1) and a t four stations on the island of Puerto Rico (Figure 2). Seven of the San Francisco Bay area stations were part of the monitoring network of the Bay Area Air Pollution Control District (BAAPCD) with whose assistance samples were collected. Two other Bay area stations were set up in the Berkeley Hills and in Benicia. The stations can be described as follows: BE. Benicia station on rural hilltop 5 km from town; BK, Berkeley Lawrence Radiation Laboratory station on top of a 12-meter building at a 300-meter altitude in the Berkeley Hills overlooking the residential areas of the city; F, City of Fremont station a few kilometers east of the Nimitz Freeway in a business-residential area; P, City

Figure 1.

Present address. California State Department of Public Health, 2151 Berkeley LVay. Berkeley, Calif. 94504 Present address, Physical Sciences Department, California State College, Stanislaus, Turlock. Calif. 95380

San Francisco Bay area station locations and wind

data

PJE2TO ? I C 0 t N

Present address, Department of Geology and Geophysics, Yale I.niversity, Kew Haven, Conn. 06520. T o whom correspondence should be addressed.

10 20 30 40 50 KP

jSC".'

, il 0(5

I Figure 2.

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10 15 2 0 2 5 YM

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Puerto Rican station locations and wind data Volume 7, Number 9, September 1 9 7 3 817

San Francisco peninsula; SF, City of San Francisco station located on top of the downtown approximately 40meter high BAAPCD building; SJ, City of San Jose station located in a business-residential area. Of the seven BAAPCD stations only SF utilized a building higher than approximately 5 meters. In general, these stations were set up to simulate environmental conditions encountered daily by persons working and living in these areas. The BK station was located on top of a 12meter high building. The four sampling stations on the island of Puerto Rico were located on the coastline at a Navy base (NC), just below cloudbase a t a Boy Scout camp (BS), on top of Pic0 del Este in a cloud forest (CF), and on the leeward side of the mountain ridge in the rain forest (RF). The samplers at stations other than RF were held by ringstands 1 meter above the roofs of one- or two-story inactive buildings. The RF sampler was located on a 22-meter tower above the rain forest tree canopy. A listing of stations, sampling periods, and total volume sampled is presented in Table I. Aerosols were collected by seven-stage Andersen cascade impactors followed by afterfilters containing 47 mm Whatman 41 cellulose fiber paper. Vacuum was supplied by Y3 hp vacuum pumps operated a t a constant flow rate of 1 cfm (1.7 m3/hr). Particles were impacted onto 1 mil (25 pm) polyethylene discs placed over the normal Andersen stainless steel collection discs. Details on the use of these materials can be found in Dams et al. (1972). Fifty percent cutoff diameters based on calibration of the Andersen impactor with unit density latex spheres and often used to describe the size of particles sampled by each stage (Flesch et al., 1967) are presented in Table 11. Aerosol samples were simultaneously analyzed for A1 and V by nondestructive neutron activation analysis using Lawrence Livermore Laboratory's (Livermore, Calif.) 3-MW reactor. A high-resolution lithium-drifted germani-

um detector was used to count the samples. Details of the counting sequence can be found in Rahn et al. (1971).

Results The results of V analyses from the San Francisco Bay and Puerto Rican studies along with some results of previous studies are summarized in Table 111. Sources of V in Bay irea. As a first step in understanding the source of V in the San Francisco Bay area we should examine abundances and size distributions of V a t the various stations. Table I11 indicates that abundances range from 2.7 ng/m3 in downtown San Francisco to 12 ng/m3 in the much smaller city of Pittsburg. Particle size distributions of V are presented in Figure 3. It should be noted that the Pittsburg station (P) is located less than 1 km from a utilities plant which burns both natural gas and fuel oil and is also within a few miles of a complex of oil refineries. In spite of the differences in total concentrations, the V size distributions remain roughly the same with sources of V apparently associated with both small and large particles. One possible source of large-particle V is soil dust. Rahn et al. (1971) and John et al. (1973) have associated total V a t these stations with a soil dust component. Since A1 was also associated with dust by the previous authors, we have therefore plotted V/Al ratios as a next step (Figure 4). It is apparent that the V/A1 ratios consistently reach a minimum in the large particle fraction in a range of ratios close to that given for average crustal material (Goldschmidt, 1954; Turekian and Wedepohl, 1961). By assuming that the entire A1 concentration is associated with soil dust and subtracting from each stage in the size distributions that component of V which could be ac-

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Table I. Stations, Sampling Periods and Volumes

San Francisco Bay Area Station

BE BK, F, L, P, R, RC, SF, SJ

Sampling period 1200 7-1 3-71 to 1200 7-16-71

1200 7-12-71 to 1200 7-16-71

Sampling vol., m3 135

179

Puerto Rico Sample

NCAl NCAl I BSAl I RFAl RFAl I CFAl CFAll

Sampling period 1200 11-23-71 to 1300 11-25-71 1345 11-25-71 to 1515 11-28-71 0950 11-27-71 to 1400 11-30-71 1015 11-23-71 to 071 0 11-26-71 0745 11-26-71 to 1100 11-30-71 1435 11-22-71 to 0900 11-25-71 1845 11-25-71 to 0830 11-30-71

Sampling vol., m3 83 125 74 117 169 64 125

Figure 3. V particle size distributions at San Francisco Bay area station locations as determined by N . A . A . I I " "

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Table I I . Andersen Impactor 50% Cutoff Diameters, L ) ~ o Andersen stage 1 2 3 4 5 6 7

818

Environmental Science & Technology

m

D50,

9.20 5.35 3.28 1.76 0.89 0.54 0.40

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Figure 4. Average and range of V/AI ratios as a function of Andersen impactor stage at San Francisco Bay area stations

Table 1 1 1 . Concentrations of V Found in This Study and Selected Previous Studies Puerto Rico

San Francisco Bay area

Previous studies

V ng/m3,

Station

V ng/m3, 20%=

BE

4.9

NCAl

0.62

Pacific Ocean

0.17 f 0.13'

Hoffman et a / .

BK

6.9

NCAl I

1.7

Hawaii

0.16 f 0.11'

Hoffman et a/.

F

7.6

BSAl I

2.2

Niles, Michigan

2.9 f 0.5

Rahn et a / .

L

7.5

RFAl

1,l

NW Indiana

4.0 f 1.0 to 18f2 600d

Harrison et a/.

Sample

Av. V , ng/rn3

Location

15%O

Authors

(1969) (1972) (1971)

P

12

RFAl I

2.7

R

5.0

CFAl

2.4

RC SF

3.3

CFAl I

1 .o

Cambridge, Massachusetts Chicago, Illinois

(1971)

Zoller and Gordon (1970)

Brar et a / .

22e

(1970) 2.7 6.7

SJ

aApproximate analytical uncertainty. *Average of 9 samples. CAverageof 106 samples. Precision about f 1 0 % . eAverage of 22 metropolitan Chicago area stations: concentrations ranged from 2.2-1 20 ng/rn3.

counted for by a soil origin, we are left with the smallparticle V size distributions shown in Figure 5 . Small-particle distributions of this type are often associated with combustion sources (Nifong, 1970). In the case of the Pittsburg station, many combustion sources which might emit V were noted. It appears reasonable to hypothesize that the V found during the Bay area experiment can be accounted for by the combination of a natural soil dust source contributing particles greater than 1 pm in diameter and a pollution source such as combustion of fuel oils contributing submicron particles. V in Puerto Rico. V shows up in surprising amounts in the rather isolated Puerto Rican stations. Hoffman et al. (1969, 1972) have also found unaccountably high levels of V over the Pacific Ocean between California and Hawaii and over the island of Hawaii itself. The V/Al ratio plotted in a manner similar to that for the San Francisco Bay area (Figure 6) seems to indicate that there are large amounts of V in Puerto Rican air not attributable to dust having average crustal abundances of A1 and V. The average V/A1 ratios found for aerosols a t the four Puerto Rican stations are compared with those found on Hawaii by Hoffman et al. (1972) in Table IV. The ratio found for California dust and crustal material

range (Turekian and Wedepohl, 1961) are also included. The Hawaiian and Puerto Rican ratios agree well but show an excess of V above or a depletion of A1 below the California dust and average crustal material. Additional data for two other elements, Cr and Co, were obtained for the NCAII and RFAII samples through long irradiation neutron activation procedures (i.e., see Dams et al., 1970). Ratios between these two elements and A1 and V might serve to clarify the sources of all of them. Table V summarizes our data from Puerto Rico samples NCAII and RFAII and gives the ratios of these elements in average crustal material and in seawater. Comparisons of the ratios in Table V indicate that: V, Co, and Cr are enriched relative to A1 in comparison with average crustal abundances, and relative to each other, V, Co, and Cr show agreement with average crustal abundances. These factors suggest that the deviation of V/A1 ratios from average crustal abundances may be due to depletions in A1 in soil-derived material rather than excesses of V from a special source such as pollution. There remains an additional line of evidence that should be considered: namely, the similar behavior of A1 and V in aerosols involved in orographic cloud formation

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Calculated soil-free V average concentration and range as a function of Andersen impactor stage at Bay area stations Figure 5.

Note highest values found at Pittsburg, Calif.

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Figure 6. V/AI ratios as a function of Andersen impactor stage at Puerto Rican stations

Volume 7 , Number 9 , September 1973

819

Table IV. Comparisons of V/AI Mass Ratios for Puerto Rican and Hawaiian Aerosols, California Dust and Average Crustal Material Puerto Rican Av

Station NC BS

RF CF

V/AI

0.042 0.011 0.089 0.021

Av Hawaiian, California dust, V/AI V/AI

(Hoffman etal., 1972)

0.024

0.0025

Crustal material, V/AI

Av (Goldschmidt, 1954), 0.0018

Range (Turekianand Wedepohl, 1961), 0.0003-0.005

Table V. Multielement Ratios in Puerto Rican Aerosols, NCA II and RFA I I Sample NCA I1 RFA II

Crustal av Seawater

V/AI

0.071 0.12 0.0018 2.0

Co/AI 0.013 0.0086 0.00049

Cr/AI 0.063 0.068 0.0025

0 10

0.050

Co/Cr 0.21 0.13 0.20 2.0

V/Co 5.5 14 3.8 20

V/Cr 1.1 1.8 0.75 40

processes in Puerto Rico (Martens and Harriss, 1973). A1 and V particle size distributions out of clouds change only slightly during cloud formation indicating little incorporation of condensing water vapor. This physical evidence suggests that both elements are part of nonhygroscopic particles, probably from a soil origin. It is possible that soil dust from both local and distant sources such as the African continent (Prospero, 1972) is being sampled.

S u m m a r y and Conclusions Both soil and combustion appear to be major contributors of V in the San Francisco Bay area atmosphere, the soil providing the larger particles and the combustion the smaller particles. V sampled in Puerto Rican experiments may be primarily from a soil source. The similar behavior of V and A1 in Puerto Rican orographic clouds (Martens and Harriss, 1973) further suggests soil origin for the V, although the soil dust does not appear to have average

crustal composition, especially in the case of A1 which is depleted.

Acknowledgment The authors thank Richard Clements and the staff of the Puerto Rico Nuclear Center for the use of their facilities and for their assistance during the collection of Puerto Rican samples. We thank Milton Feldstein and Wayman Siu of the Bay Area Air Pollution Control District for the use of their stations for our sampling sites. This paper has been improved through the comments of John W. Winchester, Florida State University, and Robert A. Duce, University of Rhode Island. Literature Cited Brar, S . S., Nelson, D. M., Kline, J. R., Gustafson, P. F., Kanabrocki, E. L., Moore, C. E., Hattori, D. M., J. Geophys. Res., 75, 2939-45 (1970). Dams, R., Rahn, K . A , , Winchester, J . W., Enuiron. Sei. Technol., 6, 441-8 (1972). Dams, R., Robbins, J. A., Rahn, K . A,, Winchester, J . W., Anal. Chem., 42,861-7 (1970). Flesch, J . P., Norris, C. H., Nugent, A. E., Jr., J. Amer. Indus. Hyg. ASS.,28,507-16 (1967). Goldschmidt, V. M., “Geochemistry,” Oxford Univ. Press, London (1954). Harrison. P. R.. Rahn. K . A , . Dams. R.. Robbins. J. A , . Winchester. J. h’.,Brar, S . , Selson, D. ‘M.,’J.Air Po’lluf. dontr. Ass,, 21,563-70 (1971). Hoffman, G. L., Duce, R. A., Hoffman, E. J., J. Geophys. Res., 77,5322-9 (1972). Hoffman, G. L., Duce, R. A , , Zoller, W. H., Enuiron. Sei. Technol., 3, 1207-10 (1969). John, W., Kaifer, R., Rahn, K. A , , Wesolowski, J. J., Atmos. Enuiron., 7,107-18 (1973). Martens, C . S., PhD Thesis, Florida State University, 1972. Martens, C. S., Harriss, R. C., J. Geophys. Res., 78, 949-57 (1973). Nifong, G. D., PhD Thesis, Cniversity of Michigan, 1970. Prospero, J. M., J. Geophys. Res., 77,5255-65 (1972). Rahn, K. A , , Wesolowski, J. J., John, W., Ralston, H. R., J . Air Pollut. Contr. Ass., 21,406-9 (1971). Turekian, K. K.. Wedepohl, K . H., Geol. Soc. Amer. Bull., 72, 175-92 (1961). Zoller, W.H.. Gordon, G. E.. Anal. Chem., 42, 257-65 (1970).

s.

Received for reuieu: December 18, 1972. Accepted May 25, 1973. Work performed in part under the auspices of the L!S. Atomic Energy Commission.

Ligand Photooxidation in Copper(l1) Complexes of NitrilotriaceticAcid Implications for Natural Waters Cooper H. Langford,’ Michael Wingham, and Vedula S. Sastri D e p a r t m e n t of C h e m i s t r y , C a r l e t o n U n i v e r s i t y , O t t a w a , Ont., C a n a d a K1S 5B6

The fate of aminopolycarboxylate compounds [all of which are potential detergent builders, components of some industrial wastes, and apparently products of secondary sewage treatment (Bender et al., 1971)] involves the reactions of their metal complexes because complex formation constants are so large (Ringbom, 1963). We are engaged in a study of the photochemical degradations that may occur under sunlight irradiation. Transformation of the organic molecules may be expected to be facile only To whom correspondence should be addressed. 820

Environmental Science & Technology

when excited states of the ligand to metal charge transfer type (Balzani and Carassiti. 1970a) are accessible in the complex. This suggests that attention be given to complexes of metals from the transition group such as Cu(II), Co(II), and Fe(II1). At first sight, such a restriction might discourage interest because of the low concentration of such metals, but there are two mitigating factors; first, the complex formation constants of aminopolycarboxylates with these metals are large, and second, the rapidity of ligand substitution processes in these systems (Langford and Sastri, 1972) ensures considerable “turnover.”