Vanadium, Copper, and Aluminum in the Lower Atmosphere between California and Hawaii Gerald L. Hoffman and Robert A. Duce Department of Chemistry and Hawaii Institute of Geophysics, University of Hawaii, Honolulu, Hawaii 96822 William H. Zollerl Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Mass. 02139
Atmospheric particulate samples were collected from a 20-meter-high tower on the windward coast of the island of Hawaii and from a ship between California and Hawaii. The samples were analyzed for N a by flame photometry, and for V, Cu, and AI by thermal neutron activation. The Na/Cu, Na,'V, and Na/AI ratios for seawater were considerably greater than those for the particulate matter, indicating a nonmarine source for Cu, V, and AI. Elemental ratios suggest that A1 and V probably come from the weathering of continental crustal material. The source of the high Cu concentrations is unknown, although contributions from man-made pollution on the west coast of North America is a possibility.
A
lthough chemical studies of air pollution have attracted an increasing amount of scientific effort over the past several years, there have been very few investigations of the global transport of air pollution particulate matter. Analyses of Greenland ice cores showed that a sharp increase in the Pb content of Greenland snows occurred shortly after the use of tetraethyl lead in automobile fuels became common (Murozumi. Chow, and Patterson, 1965). Recent studies in Barbados (Delany et cil., 1967; Prospero, 1968; Risebrough et a/., 1968) have shown that dust and chlorinated hydrocarbon pesticides are carried across the Atlantic Ocean from Africa to the Caribbean by the northeast trade winds. Rex et a/. (1969) have also shown evidence that quartz in Hawaiian soils has an eolian origin. The atmosphere between California and Hawaii is an ideal location for examining the possible transport of particulate matter from the North American continent over long distances. The mean surface pressure patterns in this region, both in summer and winter, indicate a general wind flow from California to Hawaii (the northeast trades). This general pattern of circulation often persists to heights of 6000 meters in the summer and about 3000 meters in the winter, and suggests that continental-source particulate matter may often be transported toward Hawaii on these prevailing northeast trade winds. Experimental In this investigation particulate samples were collected from a tower 20 meters high located on a lava headland on the windward coast of the island of Hawaii, 9 km. east of Hilo and approximately 320 km. southeast of Honolulu. Samples were also collected on board a U S . Coast and Geodetic Survey ship between San Diego, Calif., and Honolulu. The particulate matter was collected on glass fiber filters, using a Gelman Present address: Hawaii Institute of Geophysics, University of Hawaii, Honolulu, Hawaii 96822
Hurricane high-volume pump. The filters have a collection 0.15 p . efficiency of > 9 5 z for particulate matter with r From 1000 to 2500 m.3 of air were filtered per sample, at a rate of approximately 150 m.3/hr. The collecting instrument on board ship was located o n the bow, and every effort was made to avoid contamination by stack effluents from the ship. A third set of samples was collected from the flying bridge of a ship between Kodiak, Alaska, and Hawaii. However. for some metals, these samples were apparently contaminated by products of the combustion of heavy fuel oil on the shipindicating the great care which must be taken when sampling particulate matter from a ship. The particulate matter collected between California and Hawaii was removed by agitation of the filters in 100 ml. of distilled demineralized water. Particulate matter from the Hawaii-tower filters was removed by agitation in 100 ml. of a strongly acid solution of 8-hydroxyquinoline. The aqueous solutions were analyzed for N a by flame photometry and for Cu, V, and AI by thermal neutron activation analysis using the nuclear reactor at the Massachusetts Institute of Technology, Cambridge, Mass. The California-Hawaii samples were not analyzed for AI. The samples were irradiated for 5 min., then inactive Cu, V, and AI carriers were added, and the three metals removed from other radioactive species by chloroform extraction from the aqueous phase using a 3 Y , cupferron solution at a pH of 1. After washing with dilute sulfuric acid, the chloroform phase was counted, using a Packard 4096 pulse height analysis system. A 3-inch X 3-inch NaI scintillation detector was used for the California-Hawaii samples, and a 35 cc. Ge(Li) detector with a F W H M of 5.0 kev for the 661 kev line of I3?Cswas used for all other samples. The gamma peaks used in the analyses were as follows: 1.7 MeV y for 2.3 min. 28A1; 1.04 Mev y for 5.1 min. W u ; and 1.43 MeV y for 5ZV. V chemical yields in the separation procedure were measured by adding a known amount of 16day 48Vto the sample before chemical separation and measuring the 0.99 MeV y of 48V several days later. Cu and AI chemical yields were measured colorimetrically using dithizone and 8-hydroxyquinoline, respectively. A mixed Cu, V, and A1 standard solution was irradiated simultaneously with each sample and the standard was counted directly with no chemical separation. Results and Discussion The results of the chemical analyses are given in Table 1 . The ship positions indicated are those at the mid-point of each sampling period. Elemental mass ratios for all samples are given in Table 2, along with ratios for possible source material for the particulate matter. The uncertainties given in Tables 1 and 2 refer to the analytical precision of the analyses. Several blank filters were processed through both procedures. For the California-Hawaii samples, blank corrections were Volume 3, Number 11, November 1969
1207
Table 1. Metal Concentrations of Particulate Filter Samples Sample number 1 2 3 4 5
6 7 8 9 10
Latitude, N
6/29/67 6130167 6130167 711167 7/2/67 7/3/67 7/4/67 7/5/67 7/6/67
31’10’ 30’10’ 29’20 ’ 28OOO’ 26’30’ 25’30’ 24’00’ 22’15’ 21’10’
118’15’ 122’1 5 ’ 124’00’ 129’30 ’ 135’00’ 140’20’ 145’50’ 151’30’ 155’40’
11/15-
19’43’
Windward Hawaii tower samples 155’00’ 3.9 f 0.4 15.
11/ I 6/67 111171 1 /18/67 1 11281 1/29/67
11 12 0
Date
19’43 19’43’
’
Longitude, W Na pg/m.3 California-Hawaii samples“ 2.0 0.51 0.74 0.39 2.0 2.7 3.2 11. 24.
i0.2 i 0.05 i 0.07 i 0.04 i 0.2 i 0.3 i 0.3 =t1.
i 2.
155OOO’
2.8 i0 . 3
155’00‘
7.5 i 0.7
Cu nghn.3
V ngh.
51. i 15 21. i 7 8.5 i 3 4.4 i 2 12. i 4 7.4 zt 3 7.0 i 3 5.3 i 2 6.5 i 2
0.82 i 0 . 4 50.04 0.12 i 0.08 10.02 0.060 i 0.04 0.37 i 0.23 0.044 i 0.03 0.016 i 0.01
