COMMUNICATION
Possible Source of Atmospheric Pollution of Selenium Yoshikazu Hashimoto, Jae Y. Hwang,' and Saburo Yanagisawa Department of Applied Chemistry, Keio University, Koganei-shi, Tokyo, Japan
Table 1. List of the Samples Analyzed Nippon Petroleum Co. Raw petroleum Heavy petroleum A Arabian Petroleum Co., and others Heavy petroleum B Arabian Petroleum Co., and others Heavy petroleum C Arabian Petroleum Co., and others Nippon Petroleum Co., for oil heater Petroleum Sumitomo Mining Co., for coal heater Coal Collected at a power plant using heavy soot petroleum Soil Collected in Tokyo, Japan, and its vicinity Rubber Various automobile tires used in Tokyo area
A method of tracking down a source of elemental atmospheric pollution is based on the determination of pertinent elemental ratios in the samples of interest. As a first approach, in an attempt to study a source of selenium pollution in the atmosphere, selenium to sulfur ratios were determined in the samples of some fuels, rubbers, and soil samples by analyzing sulfur and selenium with ultraviolet-visible spectrophotometry and turbidimetry, respectively. The ratios thus obtained were compared with those of the atmospheric precipitation and particulate samples, which were found to be in the same order of magnitude as those of fuel oils and rubber products. The present study, therefore, indicates that the fuel oils can be an important source of selenium pollution in the atmosphere.
they are the main source of sulfur pollutants in the atmosphere. Rubbers were also analyzed as they are the major components of automobile tires, to which sulfur is added in the production line. Simple analysis of sulfur and selenium in those samples, however, will provide no useful information as to the source of pollution, unless the elemental ratios of a pair of elements which have similar chemical and physical properties are studied.
T
he use of selenium in industry is growing. One of the major uses of selenium compounds is in the glass industry to color glass a deep red and to neutralize iron color. It was also found lately by West (1967) that various papers contain significant amounts of selenium of physiological and toxic importance. The incineration of paper, therefore, should be an important source of selenium. However, importance of fuel as a possible source of selenium in the atmosphere has been neglected until 1967, when selenium in atmospheric samples was first analyzed by Hashimoto and Winchester (1967). They reported that the average ratio of selenium to sulfur in those samples collected in the greater Boston area with an apparent positive correlation beis about 1 X tween sulfur and selenium. It was for this reason that selenium was considered as a possible atmospheric pollutant along with sulfur, which mostly originates from fuel burning. The materials analyzed are listed in Table I. Raw petroleum, coal, heavy petroleum, and petroleum were chosen because
Procedure
The method developed by Forrester and Jones (1960) was used to decompose the samples of petroleum, coal, and rubber, while the method by Chaudry and Cornfield (1966) was utilized for the decomposition of soil samples. Separation of selenium was made as described by Hashimoto and Winchester (1967). Analytical methods are based on the procedure by Cheng (1956) and ASTM procedure (1964) for selenium and sulfur, respectively. A Model EPU-2 spectrophotometer (Hitachi, Japan), was used throughout the experiment. Results and Discussion
Applications Laboratory, Instrumentation Laboratory, Inc., 113 Hartwell Ave., Lexington, Mass. 02173 ATMOSPHERIC
The analytical results of selenium, sulfur, and their ratios are summarized in Table 11. Raw and heavy petroleum contain
SAMPLES
IO-^
10 -5
IO-^ 2
4 I
I
POSSIBLE
6
8 I
2 I
4 I
6 I
Figure 1. Variation of Se/S (collected in the greater Boston area) and comparison of their ratios with those of possible uollutants
CONTAMINANTS
a SOOT R A W PETROLEUM
\SOIL EXTRACT HEAVY PETROLEUM - A HEAVY PETROLEUM HEAVY PETROLEUM
-
-B C
Volume 4, Number 2, February 1970 157
Samples Raw petroleum 1 Raw petroleum 2 Raw petroleum 3 Raw petroleum 4 Raw petroleum 5
Wpg./g.)
Heavy pet. A-1 Heavy pet. A-2 Heavy pet. A-3
0.95 1.05 1.30 Av. 1.10
Heavy pet. B-1 Heavy pet. B-2 Heavy pet. B-3
0.50 0.70 1.05 Av.0.75
Heavy pet. C-1 Heavy pet. C-2 Heavy pet. C-2
1.65 0.89 0.80 Av. 1.12
Rubber tires 1 Rubber tires 2 Rubber tires 3
0.70 0.95 1.40
0.95 0.89 0.50 0.80 0.95 Av. 0.92
Table 11. Analytical Results of the Samples Analyzed Seis ratio S(mg./g.) (X Sample SeGg./g.) 20.9 0.45 Rubber tires 4 2.00 21.3 0.42 Rubber tires 5 1.45 16.1 0.31 Rubber tires 6 1.55 18.1 0.44 Av. 1.33 Coal 1 1.30 19.6 0.49 Av. 18.4 Av.0.42 Coal 2 1.05 12.0 0.79 Av. 1.18 8.6 1.22 Petroleum 1 0.50 12.2 1.09 soot 1a 4.30 Av. 10.9 Av. 1 . 0 3 soot 2b 0.50 16.5 0.55 soil 1 1.10 17.6 0.63 soil 2 1.30 16.5 0.46 Soil 3 1.30 Av. 16.9 Av.0.55 Soil 4 1 .oo Soil 5 1.20 18.9 0.87 Av. 1.14 20.2 0.44 Soil extract 1 0.50 18.9 0.42 Av. 19.3 Av.0.58 Soil extract 2 0.50 Av. 0.50 11.6 0.60 12.8 0.74 a Mechanically collected. 10.7 1.31 Electrically collected.
consistent amounts of both elements, while petroleum appears to have much less sulfur. The amounts of selenium in the automobile tires, coal, and soil samples are fairly comparable, even though soot, when collected electrically, and soil extract contain slightly less amounts of selenium. Amounts of sulfur, however, vary significantly depending on the samples of soot, coal, soil, and soil extract. The wide spread in amounts of sulfur necessitates, therefore, analysis of selenium to sulfur ratio to detect the source of selenium pollution. Figure 1 shows that selenium to sulfur ratios of the fuel samples analyzed here are in the same order of magnitude as found in the atmospheric precipitation and particulate samples. Particularly, the ratios of raw and heavy petroleum samples are in good agreement with those of the atmospheric samples. It would, therefore, be safe to assume
158 Environmental Science & Technology
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~~~~
~
~~~~
S(mg./g.)
Se/S ratio ( x 10-4)
15.1 14.0 14.0 Av. 13.0 2.38 2.50 Av.2.44
1.33 1 .oo 1.10 Av. 1.01 5.50 4.20 Av.4.85
3.45 138 30 1.70 1.60 2.40 1.50 1.60 Av. 1.76
1.50 0.31 0.17 6.47 8.13 5.42 6.67 7.50 Av. 6.84
0.10 0.11 Av. 0.11
50 45 Av. 48
that both raw and heavy petroleum can be a source of selenium in the atmosphere. Further study on V/Se and Te/Se ratios on the atmospheric samples and the possible pollutants will refine the analytical results so that a firm conclusion may be drawn. Literature Cited ASTM Designation, D 516-63T (1964). Chaudry, I. A., Cornfield, A. H., Analyst 91, 528 (1966). Cheng, K. L., Anal. Chem. 28, 1738 (1956). Forrester, J. S., Jones, J. H., Anal. Chem. 32, 1443 (1960). Hashimoto, Y . , Winchester, J. W., ENVIRON. SCI.TECHNOL. l ( 4 ) 338 (1967). West, P. W., Chem. Eng. News 45, 12 (1967). Receioed for reoiew September 6, 1968. Accepted October 8, 1969.
