Document gDMZ1K3g400B7x5vLBo4zD9QN

suits are also-consistent with data from searchlight probing of the lower atmo sphere on clear nights in New Mexico (12). - William M. Porch Robert J. Charlson Departments of Geophysics and Civil Engineering, University of Washington, Seattle 98105 Lawrence F. Radke Department of Atmospheric Sciences, University of Washington References and Notes 1. R. A. McCormick and J. H. Ludwig, Science 156, 1358 (1967). 2. R. A. Bryson, Weatherwise 21, 56 (1968); R. J. Charlson and M. J. Pilat, J. Appl. Meteorol. (note) 8, 1001 (1969). 3. C. E. Junge, keynote address, International Conference on Condensation and Ice Nuclei, Vienna, Sept. 1969. 4. E. C. Flowers, R. A. McCormick, K. R. Kurils, J. Appl. Meteorol. 8, 955 (1969). 5. N. C. Ahlquist and R. J. Charlson, Environ. Sci. Technol. 2, 363 (1968), 6. R. J. Charlson, N. C. Ahlquist, H. Selvidge, P. B. MacCready,, Jr., J. Air Pollut. Contr. Ass. 19, 937 (1969). 7. V. JSiedentopf, Z. Meteorol. 8, 417 (1947). 8. J. J. Kelley, Vnlv. Wash. Dep. Atmos. Sd, Tech. Rep. NR 307-252 (May 1964).- 9. L. F. Radke and P. V. Hobbs, /. Atmos. Sd. 26, 281 (1969). 10. R. J, Charlson, N. C. Ahlquist, H. Horvath, Atmos. Environ. 2, 455 (1968). 11. US. Public Health Serv. Publ. No. 637 (1958); ibid. No. 978 (1962). 12. L. Elterman, Environ. Res. Pap. No. 241 [Air Force Cambridge Res. Lab. Rep. 66-828 (Dec. 1966)J- 13. W. H. Fischer, /. Appl. Meteorol. 6, 958 (1967). 14. Support for the work at Mount Olympus was provided under grant GA 780 from the Atmospheric Science section of the National Science Foundation and contract 14-06-D- 5970 from the U.S. Department of Interior, Office of Water Resources. Support for the work at Point Barrow was provided under contract No. N0014-67-A-0103-0007 from the Office of Naval Research (Arctic Program) and grant GA 17381 from the Atmospheric Science section of the National Science Foundation. Support for the design of the nephetomeier and the measurements was provided under grant AP00336-07 from the National Air Pollution Control Administration, U.S. Public Health Service. 12 June 1970; revised 24 July 1970 Humic Substances: Fulvic Acid-Dialkyl Phthalate Complexes and Their Role in Pollution Abstract. Fulvic acid is a water-soluble humic material with relatively low molecular weight that occurs widely in soils and waters. It can combine with lyophobic organic compounds such as alkanes, fatty acids, and dialkyl phthalates to form stable "complexes" that are soluble in water. Fulvic acid in an aquatic environment may act as a vehicle for the mobilization, transport, and immobiliza tion of organic compounds, some of which may be toxic pollutants. Humic substances are among the be extracted by organic solvents from most widely distributed natural prod untreated fulvic acids; the remainder ucts of plant decomposition on the was extractable only after methylation earth's surface, occurring in soils, lakes of the fulvic acid and adsorption on (1), rivers (2), and the sea (5). In spite neutral aluminum oxide (6). Even of their extensive distribution, little is though the nature of the molecular known about their chemical structure forces that hold the alkanes and fatty and svnthesis or mechanisms of their acids to the fulvic acid is still a matter degradation and adsorptive properties. for conjecture, results from infrared Of special interest are fulvic acids which spectroscopy indicate that methylation are water-soluble, relatively low-molecu reduces hydrogen bonding in the fulvic lar-weight humic materials that can acid. This, in turn, may change the con form stable complexes with metal ions formation of the fulvic acid polymer and hydrous oxides (4), can interact in such a manner as to make these com with clay minerals (4), and are physio pounds extractable by organic solvents. logically active (5). Although interac We report here the isolation and identi tions between fulvic acid and inorganic fication of small amounts of dialkyl soil constituents have been investigated, phthalates in fulvic acid and suggest a very little is known about reactions of possible role of fulvic acid in pollution. fulvic acid with organic compounds of The fulvic acid was extracted from concern to man, especially with those the Bh horizon of a podzol soil in Prince that are environmental pollutants. Edward Island. Methods of extraction, We recently reported the isolation purification, and drying as well as sev from a fulvic acid of small amounts of eral physical and chemical character normal and branched cyclic alkanes and istics of the fulvic acid have been de of fatty acids, ranging from C14 to C30, scribed (4). Briefly, the fulvic acid is that account for 0.25 percent of its dry, a chemically and biologically stable ash-free weight (6). Less than 10 per polyelectrolyte with a number-average cent of the alkanes and fatty acids could molecular weight (measured by vapor- pressure osmometry) of 951 and con tains 9.1 meq of COOH, 6.9 meq of total OH, and 3.1 meq of C O groups per gram (4). In the present investiga tion 100 g of air-dry fulvic acid (1.0 percent ash) was extracted for 24 hours in a Soxhlet apparatus first with 1 liter of n-hexane, then with 1 liter of ben zene, and finally with 1 liter of ethyl acetate. The n-hexane extract contained small amounts of alkanes ard fatty acids, but none of the extracts c< intained dialkyl phthalates. The remaining fulvic acid (98.5 g) was then methylated with silver oxide-methyl iodide (7). Four successive methylations increased the methoxyl content from 0.2 to 28.2 percent. The methylated fulvic acid (75.0 g) was refluxed with 1 liter of nhexane. The n-hexane extract contained trace amounts of dialkyl phthalates. The methylated fulvic acid was then dis solved in benzene. The benzene-soluble material (41.3 g) was chromatographed over neutral aluminum oxide (2000 g) and eluted successively with 3000 ml of n-hexane, benzene, benzene-ethyl ace tate (9:1 by volume), and benzeneethyl acetate (1:1 by volume). Each extract was further-fractionated by re peated thin-layer chromatography on A1203 and silica gel. Only the benzeneethyl acetate (1 : 1) extract was found to contain dialkyi phthalates. The pro cedure employed for their isolation was as follows: The benzene-ethyl acetate (1:1) extract (0.51 g) was first sepa rated by preparative thin-layer chroma tography on A1203 with toluene-ethyl acetate (3:1 by volume) as solvent. The material near the solvent front was removed from the plates, extracted with ethyl acetate, and refraction ated on ALO3 plates with tolueneethyl acetate (9:1); the yield was 0.04 g of extract The location of phthalates on the plates was detected by examina tion under an ultraviolet lamp and by spraying a guide strip with hydroxylamine-ferric reagent (8). Four fractions were scraped off the thin-layer chro matographic plates; these fractions were eluted with ethyl acetate and further separated by preparative gas chromatog raphy (Hewlett-Packard model 402 flame ionization detector, 122 X 3 mm glass column packed with 3 percent OV-17 on Chromosorb W HMDS, 60 to 80 mesh, programmed from 200 to 300C at a rate of 7.5CC per minute). Materials representing the four major peaks, I, II, III, and IV, were eluted from the gas chromatographic column, collected in capillary tubes, and identi fied by ultraviolet snectroscopy, infra- 16 OCTOBER 1970 ^ ( e ,-j e fY) A A-2-1 * z- DSW 552560 317 STLCOPCB4090977 on a Beckman IR 12 spectrophotom eter equipped with a beam condenser), and mass spectrometric analysis (Con solidated Electrodynamics Corporation model 21-490 mass spectrometer, with the use of a heated direct-inlet probe). Component I (5.4 mg) was identified as bis(2-ethylhexyl) phthalate, compo nent II (3.5 mg) was dibutyl phthalate, component III (2.0 mg) was dicyclo hexyl phthalate, and component IV (2.0 mgj was benzyl butyl phthalate. The ultraviolet, infrared, and mass spec tra of each component were identical with those of the known ester to which the component corresponded and which was prepared by esterifying o-phthalic acid with the appropriate alcohol or al cohols and using concentrated H2S04 as catalyst. The base peaks in all the mass spectra were at mle 149, typical of dialkyl phthalates (9). The yield of each component was estimated from analytical gas chromatography and from the weight of each fraction. In total, about 13.0 mg of dialkyl phthalates was isolated from 100 g of fulvic acid. On the basis of preliminary experiments with known phthalates, at least 50 per cent of the starting material was lost during the separation procedure. On the assumption that similar losses occurred in the case of the fulvic acid extracts, phthalates may account for up to 0.03 percent of the dry weight of the fulvic acid. It is noteworthy that, like alkanes and fatty acids, most of the dialkyl phthalates could be extracted from the fulvic acid only after methylation and adsorption on aluminum oxide; we found only traces of dialkyl phthalates in the original soil sample and in alka line, extracted, nonpurified fulvic acid. The origin of the dialkyl phthalates in the fulvic acid is uncertain. Phthal ates are used in industry in the prepara tion of alkyd resins, as plasticizers and lubricants, and for dyes (10). We sus pected that the phthalates were con taminants that had interacted with the fulvic acid during the extraction and purification procedure. All solvents were purified by distillation through highefficiency columns and were found to be free of phthalates. Hot toluene wash ings of a polyethylene bottle used in the extraction procedure did not contain any alkyl phthalates. Prolonged extrac tion of 50 g of oven-dry Rexyn-101 exchange resin in the Na-form with 300 ml of hot toluene yielded 2.1 mg of solids in which we identified about 0.2 mg of component I and possibly traces of components II and IV, Cifrulak (11) reports the occurrence of unidentified 318 ui cngaui\J extracts OI SCV- eral soil samples that had been neither methylated nor in contact with ex change resins but that, in contrast to our fulvic acid, had been vacuum-distilled for several hours. The phthalates re ported by Cifrulak may have originated from the oil in the vacuum pump or from polluted soils. One cannot, how ever, exclude the possibility that the di alkyl phthalates were produced biosynthetically. They have been reported to occur in plants (12), petroleum (13), and as fungal metabolites (14). Administrations of components I and II are toxic to rats (15) and rabbits (16)\ component II has a severe effect on the hatching of chicks (17). How the inter action of alkyl phthalates with fulvic acid modifies their toxicity merits in vestigation. Our results show that fulvic acid can interact with lyophobic organic com pounds, some of which may be pollut ants, and solubilize them in water by a yet unknown mechanism. Fulvic acid may thus mediate the mobilization, transport, and immobilization of such substances in an aquatic environment. Gunnar Ogner* Morris Schnitzer Soil Research Institute, Canada Department of Agriculture, Ottawa References and Note* 1. R. Ishiwatari,, Soil Set. 107* 53 (1969).--- - 2. W. L. Lamar, US. GeoL Survm Prof* Pap 600-D (1968), p. D-24. . ` 3. M. Rashid and L. H. King, Gcoehlm, osm&- chim. Acta 33, 147 (1969). 4. M. Schnitzer, Soil Sci, Soc. Ainer. Proc. 33 75 (1969). * 5. - - and P. A. Poapst, Nature 213, 59g (1967); W. Lange, paper presented at 13th conference of the International Association for Great Lakes Research, 31 March 1970 Buffalo, N.Y. 6. G. Ogner and M. Schnitzer, Geochim. Cosmochim. Acta, in press; M. Schnitzer and G. Ogner, Israel J. Chern., in press. 7. D. H. R. Barton and M. Schnitzer, Nature 198, 417 (1963). 8. J. G. Kirchner, Thin-Layer Chromatography (Interscience, New York, 1967), p". 163. 9. R. M. Silverstein and G. C. Bassler, Spectro metric Identification of Organic Compounds (Wiley, New York, ed. 2, 1967), p. 24. 10. J. Cerbuiis and J. S. Ard, J. Ass. Ofjfic. Anal. Chem. 50, 646 (1967). 11. S. D. Cifrulak, Soil Scl. 107, 63 (1969). 12. S. Hayashi, Y. Asakawa, T. Ishida, T. Mat- suura, Tetrahedron Lett. 50, 5061 (1967). 13. X. A. Breger, J. Amer. Oil Chem. Soc. 43, 197 (1966). 14. N. Sugiyama, C. Kasliima, M. Yamamoto, T. Sugaya, R. Mohri, Bull, Chem. Soc. Jap. 39, 1573 (1966). ' . 15, M. Radeva and S. Dineva, Khtg. Zdraveopaz- vane 9, 510 (1966) (Bulgarian) [read in Chem. Abstr. 66, 103632 z (1967)]. J6. D. Calley, J. Autrian, W. L. Guess, /. Pham. Sci. 55, 158 (1966). 17. S. Haberman, W. L. Guess, D. F. Rowa, R_ O. Bowman, R. K. Bower, Tech. Pap. Reg. Tech. Conf. Soc. Blast. Eng., New York, Sept. 1967, p. 28 [read in Chem. Abstr. 67, 115358 y (1968)1. 18. We thank J. G. Desjardins for technical as sistance. * Visiting scientist from the Forest Soil Fertiliza tion Group, .Norwegian Forest Research Insti tute, Vollebekk. 5 June 1970; revised 21 July .1970^ Sulfur; Abstr'-transpot simple i data am study. 1 observer i From1 has bee some su; ponent i: tation > Europe ; evidence papers . One rea nent da' a contii tain. ^ Blokk' anisms 1 fur corr circulati compoui Europe. J sulfur p: tially t Europe ^ From the desk of E. MUSCHICK 10/23/70 Copies sent to E. L. Kaiser R. V. Johnson W. P. V/aychoff W. E. Schalk D. S. Kaminer J. E. Springgate M. . Farrar J. R. Darby E. V. John 55256t pS'N re utants are ilation. A lean wind ed in this ate to the tly reanaconcludes :onceming series are Delusion." might be imena, as 1kited out. erved de in Rotterions from ipletely be l circume winters emissions 1 the local relatively ;moval of = in be anen a sub SCIENCE, VOL. 170 --4 : STLCOPCB4090978