(13) Scruggs,G. D., U S . Fish and Wildlife Service, Special Scientific Report-FisheriesNo. 370, U S . Dept. of Interior, 1960. (14) Donahue, A. E., “Chemical Analysis for Water QualityTraining Manual”, EPA-430-1-73-003,USEPA, Cincinnati, Ohio, 1973. (15) U S . EnvironmentalProtection Agency, “Methodsfor Chemical Analysis of Water and Wastes”, EPA-625-6-74-003,NERC, Cin-
cinnati, Ohio, 1974.
(16) Mathis, B. J., Cummings, T. F., Water Resources Report No.
WRC-71-0041, Univ. of Illinois, Hydrosystems Lab, NTIS PB-
199713, 1970. (17) Boyden, C. R., Nature, 251,311 (1974).
Receiued for reuielv August 15, 1977. Accepted March 16, 1978. Work supported i n part through contracts with the Ohio Department o f Natural Resources.
NOTES
Sulfur Isotope Distribution in Sulfates from Surface Waters from the Northern Jordan Valley, Israel Arie Nissenbaum Isotope Department, Weizmann Institute of Science, Rehovot, Israel
Samples of surface waters from the Northern Jordan Valley, Israel, and Lake Kinneret (the Sea of Galilee) are analyzed for TDS, C1, SO4,and the S34/S32ratios of the dissolved sulfate. The 6S34values for sulfur isotopes range from around +4%0 in the fresh water to +19 to +23%0 in the saline springs. The regular increase in S34/S32with salinity is explained by a mixing model between rainwater-derived groundwater = +4 to +9%0) and slightly evaporated seawater (6S34around +21%0). The isotopic evidence argues against derivation of sulfate from oxidation of igneous or sedimentary sulfide, and the sulfide that occurs in the saline springs may originate from bacteriogenic reduction of marine-derived sulfate, a t depth.
The fresh waters of the Northern Jordan Valley are among Israel’s most important natural resource. Lake Kinneret (the Sea of Galilee) is being used as the country’s principal water reservoir. Due to this the study of these waters has been a major task of Israeli hydrologists and hydrogeochemists. The source of salts in these waters has been a controversial subject for many years. Although the origin of salts in the fresh water north of Lake Kinneret has usually been ascribed to airborne sea salts, far less agreement has been achieved with regard to the source of salts in the saline waters in the Lake Kinneret basin. Mazor and Mero ( I ) critically discussed the possible sources such as derivation from outflushing of connate water sources, derivation from airborne marine salts ( 2 ) , dissolution of underlying salt deposits, entrapment of highly saline brines from previous evaporative cycles in the Jordan Valley, or infiltration of Dead Sea or Mediterranean seawater. Mazor and Mero ( I ) concluded that the hydrogeochemical data best fit a model that related the salts in the saline springs to oceanic water which infiltrated the Jordan Valley and then percolated downward into the tectonically shattered rocks of the Jordan graben. Later tectonic activity enabled mixing of these waters with local fresh water in various proportions to give the wide variation in chemical composition observed in the water of the Kinneret Basin. The purpose of this report is to show the possible use of S34/S32ratios of sulfates dissolved in water as a tool for choosing between the alternative hypotheses. Moreover, increase in the development of the Northern Jordan Valley is 962
Environmental Science & Technology
expected to interfere in the distribution of several elements, including sulfur, in this region. The present data could thus be used as a baseline study for the assessment of such interference. Materials and Methods
Sampling. Sampling of the water sources was conducted twice, once in April immediately after the rainy season, and once in July in the middle of the summer. All the water sources were collected in a two-day period. The samples were collected in polyethylene bottles and transferred immediately to the laboratory for chemical analysis. Sampling locations are given in Figure 1. Experimental, Chloride was analyzed by argentometric titration and sulfate gravimetrically as BaS04. This Bas04 was used for isotopic analysis following the preparation technique described by Kaplan et al. (3).The isotopic measurements were performed on a dual-collector, dual-inlet Nuclide mass spectrometer. The results are expressed in the 6 notation: 6S34%0
=
R sample - R standard
[
R standard where R is the ratio S34/S32, and the standard is Canon Diablo troilite. The degree of saturation of gypsum (IAP/KT) was calculated using the WATEQ computer program ( 4 ) . Results
Data on total salts, chloride and sulfate content, and in the sampled water sources are given in Tables I and 11. For convenience, the data are given separately for the fresh waters of the Jordan River and its tributaries (Table I) and for the waters from Lake Kinneret and its surroundings (Table 11). The geographical division is also expressed very markedly in the provenance of S34.The isotopic values for the samples collected north of Lake Kinneret are depleted in S34(with the exception of the Hermon River sample) and fall in the +2 to +10%0 range. On the other hand, the sulfate-rich water from the Lake Kinneret basin displays much higher S34values. The samples from Lake Kinneret itself show, as expected, intermediate values due to its salts being partially contributed by the Jordan River and partially from submarine saline springs.
0013-936X/78/0912-0962$0 1.OO/O
@ 1978 American Chemical Society
A major unknown in attempting to establish the source of sulfate in surface water is the isotopic composition of sulfate in rainwater. For this purpose eight rainwater samples have been analyzed. Two principal values are obtained: +4 and +9%0 (Table 111).Those values are within the range for atmospheric sulfates ( 5 ) .Samples with lower S34values probably result from a higher contribution of fossil fuel-derived sulfur, whereas the samples enriched in S34probably represent a higher contribution of seawater-derived salts with 6S34 N +20%0.Thus, the difference between the depleted Tel Aviv samples and the heavier Naharya samples, which were both collected very close to the Mediterranean shore, is tentatively
Figure 1. Map of sampling locations Numbers correspond to sample numbers in Tables I and II
ascribed to the much heavier industrialization of the coastal plain near Tel Aviv. The isotopic composition of the inland samples will be determined by the pathway of the rain clouds.
Discussion In the introduction, the hypotheses as to the origin of salts in waters from the Northern Jordan Valley were briefly summarized. The isotopic data (Tables 1-111) allow us to minimize the number of working hypotheses. As Figure 2 indicates, the isotopic composition of sulfate in surface water from the Northern Jordan Valley is best explained by a mixing model between seawater sulfate and rainwater sulfate. In the area north of Lake Kinneret the sweet water represents almost exclusively sulfate derived from recharging rainwater, although minor contribution from marine-derived sulfate, presumably through dissolution of sulfate from the aquifer rocks, can be detected. An exception is the Hermon river whose V4-enriched sulfate, especially in the summer, largely appears to be derived from marine sulfate. The recharge area for this river is the uplifted Jurassic block of Mt. Hermon. It is therefore possible that the dissolved sulfate originates from Triassic and Lower Jurassic evaporites that are known from the subsurface of this region and whose 6S34values are in the range of +15.5 to t l 8 % 0(Table IV). No isotopic evidence exists for sources such as oxidation of igneous or sedimentary sulfide or derivation from the sulfur of peats that are present in the Hula Canal area [6S34 for Hula peat is +2.3%0(6); 6S34for hydrothermal Galena from the Hermon area is -5.5%0 (7)]. As mentioned earlier, the isotopic composition of sulfate in Lake Kinneret is determined by the relative proportions of Jordan River sulfate and sulfate derived from saline springs debauching at the lake bottom. An exceptional case is the sulfate from the Yarmook River, which probably represents rainwater evaporated by a factor of 3 to 5 with no additional sulfate from other sources. The saline springs around Lake Kinneret show values consistent with marine sulfate as the major source. Where small amounts of sulfides occur in the water, as for example in the Tiberias hot springs (ca. 1 mg H2S/L), the isotopic fractionation between the sulfide and the sulfate (6S34H2S = -15%0,01= 1.0030) can be interpreted as indicative of bacterial reduction of marine sulfate and show no evidence for reoxidation of sulfides. Alternatively, the observed fractionation factor could be explained by isotopic equilibration of the sulfide with sulfate at temperatures around 200 "C. Since similar fractionation factors have been observed for nonthermal water in the Jordan Rift area ( 8 ) , the biological hypothesis is favored at present.
Table 1. Chemical and Isotopic Data on Surface Water North of Lake Kinneret No.
Sample
1
Dan River
2
Sneer River
3
Hermon River
4
lyon River
5 6
Jordan River at Hula Canal Jordan River at Gesher Hapkak
Sampllng month
July April July April July April July April July April July April
TDS
CI
so4
bS34 ( % o )
237 286 200 287 289 270 280 294 354 31 1 335 343
17 11 11 11 14 10 19 14 28 14 21 15
18 10 2 10 45 9 2 24 25 21 25 32
4-4.1
... +2.6 +4.1 4-17.8 +11.8 4-13.0
(-1 +6.5 +8.1 4-10.6
4-6.5
0.001 0.005 0.021 0.001 0.001 0.01 1 0.009 0.01 1 0.017
Volume 12, Number 8, August 1978
963
Table II. Chemical and Isotopic Data on Surface Water Sources from Lake Kinneret Area NO.
7
a 9 10
11 12 13 14 15 a
Sample
Lake Kinneret (surface) Lake Kinneret (20 m) Lake Kinneret (42 m) Ein Fulia, spring #6 Ein Nur (Tabkha) Tiberias Main Hot Spring Tiberias Roman Hot Spring Barbootim underwater spring Yarmook River
Sampllng month
TDS
July April July April July April July April July April July April July April June
a95 ai0 923 846 929 a77 1a73 2124 4300 1876 30541 30396 29207 27829 5756
ago 2623 a77 17896 17960 17404 17360 3172
July April
a24 572
104
Sampling slatlon
Tel Aviv Naharyia Tirat Yael
Location
Month
Central MediterraneanCoastal Plain Northern MediterraneanCoastal Plain Northern Galilee Highlands
Jerusalem Central Highlands Dafna Northeastern Jordan Valley
6S34 (%)
Dec-Jan Feb Dec-Jan Feb-April Jan APr Jan-Feb Jan-Feb
f3.7 $4.4 $8.4 +8.2 +3.6 +3.9 +8.7 +3.5
I0,OOC
I ,ooc
\
0
0
m
I oc
-10 -5
0 +5
+IO +I5 +20 +25
Figure 2. Relationship between bS3, (SO,) and concentration sulfate in investigated water 0 Sample from Lake Kinneret; X samples North of Lake Kinneret. Lines represent possible tracks of changes of concentration of sulfate and/or 6S34 by several geochemical processes.(Dueto graphic limitations, samples with similar sulfate content and 6S3' values are represented by single mark) 964
382 347 382 347 368 368
aao
ia
so4 67 63 66 68 90 68 119 123 173 77 740 786 776 a27 243 104 56
6S34
(%bo)
$12.2 $15.7 $12.5 $17.4 +15.1 $13.0 (-)
+ia.a +19.9 $19.3 $23.5 +15.9 $22.8 $21.7 $20.8 $6.6 +7.3
IAPlKT (gypsum)
0.023 0.024 0.026 0.026 0.019 0.025 0.058 0.098 0.13 0.06 0.898 0.94a 1.01a O.7ga
0.04 0.02
Due to high water temperature (ca. 60 OC), solubility was calculated for anhydrite rather than gypsum.
Table 111. Sulfur Isotopes in Rainwater Sulfate from Israel
--E"
CI
Environmental Science & Technology
If indeed the isotopic values of the dissolved sulfates represent a mixture of recent rainwater- and seawater-derived sulfate, then it should be of interest to pinpoint more accurately the geologic source of marine sulfate. Table IV gives isotopic values for evaporites from Israel. Another minor occurrence of gypsum in the Central Jordan Valley is thin gypsum intercalations in the U. Pleistocene Ubeidia formation. Samples, however, were not available for analysis. The 6S34 values indicate that the major phase of evaporites in Israel, the Triassic, has too low 6S34values to serve as the source for sulfates. The same is true for the evaporites of the Lisan formation (Upper Pleistocene), which are widespread in the Rift Valley. The most suitable contributor from an isotopic point of view seems to be Miocene gypsum or anhydrite. However, Mazor and Mero ( I ) argue that the chemistry of the saline water is not compatible with dissolution of gypsum. It is therefore probable that the model of Mazor and Rosenthal(9) and Mazor and Mero ( I ) provides the best explanation for the isotopic data. According to this model the major source of salts in the Lake Kinneret basin is trapped ocean water, presumably slightly evaporated first, as supported by 0lsand D data (IO).The waters of the Tiberias hot springs are assumed to best represent the trapped ocean waters which were slightly modified by interaction with the reservoir rocks in which they were trapped (9).The saturation values for anhydrite in those springs are compatible with seawater concentrated by a factor of 2 to 3. Similar concentration factors were suggested based on the isotopic composition of the water (10). It is possible that the hypothesis of the dual source of sulfate in certain groundwater systems may be widely applicable. Rightmire et al. ( 1 2 ) arrived a t similar conclusions from a thorough study of the Floridian and Edwards aquifers in the USA. Presently, the chemical data available for the Northern Jordan Valley system are not sufficient to apply the approach of Rightmire et al. (11)to differentiate between seawater and gypsum sources for the marine sulfate.
Acknowledgment I thank J. R. Gat (WIS) and E. Wakshal (H.U.) for constructive discussions, and I. Zak (H.U.) for meticulous, constructive criticism.
Table IV. Sulfur Isotope Data on Potential Evaporitic Sources for Sulfates in the Northern Jordan Valley Sample type
Sampling locatlon
Range of
Age
bS34(%.)
Comments
Gypsum
Northern Negev
Middle to Upper Triassic
4-15.7 to 4-16.5
Gypsum Gypsum Anhydrite
Northern Negev Northern Negev Coastal Plain and Gulf of Suez Central Jordan Valley
Upper Triassic Upper Cretaceous Miocene
+17.2 to +17.8 +16.8 to +18.5 +21.7 to +22.7
Neogene (Up. Miocene?) Neogene
+16.4 to +17.1
Bira Formation
+18.3 to +19.5
Sedom Formation
Gypsum and anhydrite Gypsum and anhydrite Gypsum Gypsum
Dead Sea Basin, Mt. Sedom Central Jordan Valley Dead Sea Basin
Up. Pleistocene
-4.1
Up. Pleistocene
-7.7 to -19.5
Lisan Formation, near Maoz Hayim Lisan Formation, near Masada
(7) Nissenbaum, A., “Sulfur Isotopes in Sulfur Bearing Rocks and Minerals from Israel”, Weizmann Institute, unpublished data, 1977. (8) Nissenbaum, A,, Kaplan, I. R., in “Environmental Biogeochemistry”, Vol 1,pp 309-25, J. Nriagu, Ed., Ann Arbor Sci. Publ., Ann Arbor, Mich., 1975. (9) Mazor, E., Rosenthal, E., Isr. J . Earth Sci., 16, 198 (1967). (10) Gat, J. R., Mazor, E., Tzur, Y., J . Hydrol., 7,334 (1969). (11) Rightmire, C. T., Pearson, F. J., Back, W., Rye, R. O., Hanshaw, B. B., in “Isotope Techniques in Groundwater Hydrology,” Vol2, pp 191-207, Int. Atomic Energy Agency, Vienna, Austria, 1977.
Literature Cited (1) Mazor, E., Mero, F., J . Hydrol., 7, 318 (1969). (2) Loewengart, S., Bull. Res. Counc. Isr., 10G, 183 (1961).
(3) Kaplan, I. R., Emery, K. O., Rittenberg, S. C., Geochim. Cosmochim. Acta, 27,297 (1963). (4) Truesdell, A. H., Jones, B. F., WATEQ, “A Computer Program for Calculating Chemical Equilibria of Natural Waters,” Nat. Tech. Info. Service, U.S. Dept. of Commerce, PB-220-464. (5) Jensen, M. L., Nakai, N., Science, 134,2102 (1961). (6) Nissenbaum, A., Kaplan, I. R., Lirnnol. Oceanogr., 17, 570 (1972).
Samples from Makhtesh Ramon, Makhtesh Katan, and Sherif Maktesh Ramon Ora Shales, Gerofit
Receiued for reuiew J u l y 20, 1977. Accepted February 7, 1978.
Cyano-arenes Produced by Combustion of Nitrogen-Containing Fuels George R. Dubay and Ronald A. Hites” Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Mass. 02 139
Cyanonaphthalenes (both isomers) and cyanoacenaphthylenes (four isomers) were identified in the soot generated by the combustion of aromatic hydrocarbon fuels doped with 6-30% pyridine. These were by far the most abundant nitrogen-containing organic compounds in this combustion effluent; multiring, nitrogen heterocyclic compounds, such as those commonly observed in airborne particulate matter, were a minor component. These identifications were made by gas chromatographic mass spectrometry following a preliminary separation by alumina column chromatography. The environmental significance of these findings is discussed. Certain organic compounds in soot cause cancer in man ( 1 ) . Determining the structures of these compounds and understanding their biological activities have been the subjects of intense research over the last 50 years (2).It is now known that the major class of carcinogenic compounds associated with soot is the polycyclic aromatic hydrocarbons (PAH) ( 3 ) .Nitrogen-containing aromatic compounds (aza-arenes) are also associated with soot ( 4 ) ,and some are known to be carcinogenic ( 5 ) .However, because they are much less abundant than PAH, these compounds have received proportionately less attention. In the future, however, it is likely that the environmental abundance of aza-arenes will increase as fuels 0013-936X/78/09 12-0965$01.00/0 @ 1978 American Chemical Society
higher in organic nitrogen content are burned. We have, therefore, undertaken the identification of the major azaarenes produced by the combustion of a model fuel containing 1-6% nitrogen. Several researchers have developed methods for the analysis of aza-arenes in atmospheric particulate samples based on thin-layer, gas, paper, high-pressure liquid, and column chromatography and on electrophoresis (6-10). All of these techniques begin with a solvent-solvent extraction utilizing strong acid to partition the basic aza-arenes away from the PAH. This procedure obviously discriminates against neutral aza-arenes that might be present. To avoid this problem, we have separated the aza-arenes from the bulk of the PAH by alumina chromatography using gradient elution. Once the compounds are separated from the PAH, the identification of the exact molecular structures of aza-arenes is still very difficult. Almost all assignments made in the literature are, to some degree, ambiguous. Assignments have been based on gas chromatographic retention information and on fluorescence, UV, or electron impact mass spectra (6-10). In these analyses, all the possible isomers of a particular molecular structure have not been available. Hence, by use of these techniques, there is no criterion by which the unavailable isomers can be ruled out. T o address the problem of determining the precise molecular structure of compounds produced by combustion, we have Volume 12, Number 8, August 1978
965
