Document 82wGJw6Oya4gVRDQONroozz5d

u, Nature Vo!. 252 November 29 1974 -..... .................. w J. A. KK. M. Kops J. F. v:d. Vate JAN-ft tQTr: ........... L. T. M, Hermans ' G. Dmq'ETS Slichtint; Reactor Centrum Nederland, Hoofdkantaor-Schcveningsweg 112, ' "S-Gravcnhagef-Ondersockccntrum: Petten (N-H),J '--' ' " The Netherlands ; . ... . .......... ' > ... Received June 28; revised August 28, 1974. ` Vomcla, R. A'., and Whitby, K. T., J. Colloid Interface Sci., 15' 568-576 (1967). - * Stober, W., afid Flachsbart, H., >iv. Sci. Techno!., 3, 1280-1296 (1969). * ". * Wriglcy, N. G., J. Ultras!met. Res., 24, 454-464 (19'68). , 4 Stober. W., Flachsbart, H., and Hochraincr, D., Stanh, 30,277-285 (1970). _ \. 5 Stober, \V., io Assessment of Airborne Particles (edrt. by Mercer, Morrow, and Sibber), 249 (C. C. Thomas, Springfield, 1972). * Drake, R. L.,'- in Topics in Current Aerosol Research (Parts) (edit. by Hidy, arid Rrock), 201, (Pergamon, Oxford, 1912). Decline of* PCB concentrations in North Atlantic surface water ./ OLYC11 LORObiphenyl (PCD) concentrations in N^rth Atlantic surface watcrs,havc declined fortyfold since 1972, following the cessation of .Certain industrial uses of those';compounds. Industrial sales of PCB for use in products which'-would allow leakage to the environment, for example in plaslifcs, inks and^ paints were stopped in the United States and Sweden during 1970-711; and'in 1972-73 other European countries and Japan initiated a similar action*. In 1971 and 1972 average surface concentrations^ PCB in the open North Atlantic.Ocean were about 30 ng l'-1 (ref. 3 and C. E. Olncy and J. J. Quinn, unpublished), fiy April of 1973 the concentration in the Sargasso Sea had been induced to 1 ng 1~` (ref. 4); five months later we found that the'decline had levelled at 0.8 ng l-1, a concentration which was still present in February 1974 in the. north-west Atlantic. The accumulated data are presented in Table 1. These observations revealing a reduction in surface water concentra tions of PCB Compare well with our February 1!#74 measure ments of a tenfold decrease of PCB in the atmosphere over the north-west Atlantic since 1973 (ref. 5), and a fivefold decrease *4 . Table 1 PCB" concentrations in North Atlantic surface waters* ' 1971-74 2 Date Mean PCB) (ng I-1) Sampling . region No. of Anaiyticall Ref. samples Method 8/71 25 * Iceland to Nova Scotia 7/72 \ 41 u Newfoundland to Portugal 8/72 36 . Portugal to 8 8 \ Norwegian Sea 11 9/72 30 .. Woods Hole to Bermuda 27 4/73 : 1 Sargasso Sea 9/73 2 . Azores to 09N,40W 8 i to Barbados 10 9/73 0.8 Sargasso Sea to . New York Bight 2/74 0.8 ^ New England . 9 : Continental Shelf 6 JA 1. ;B { 3/ ;c . 3 ,,-c 3 aA 4 *c 3 6 c . . 3 .c 3 4 0-30 nu ' ? t Blank values for PCB in methods A, B and C werfc 0.9, 0.5 and 0.3 ng I *, respectively. Replicate analyses using methods B or C snowed an average variation of J- 20%atlhc I ngl"1 level. Quanlitar uon methods are presented in refs 3, 5, 6. . J A, Extraction of 0.5-3.8 I with chloroform or dieMoromethane; B, extraction of.201 with 5% ether in hexane; C, passing 40-60 I through Amberlltc XAD-2 resin followed by elution-with boiling acetonitrile. ' *' 5CE Olncy and J. J. Quinn, unpublished information. 387 since 1972 in CU content of mixed plankton collected along 09"N latitude in September of 1973 (ref. 6). The data require that about 2x 10* tons of PCB were lost from the upper 200 m in less than one year5. To explain this loss, four processes must be seriously considered: (1) apparent dilution of dissolved PCB by vertical and horizontal advcction and diffusion; (2) association of PCB with sedimenting particles; (3) evaporative codistillation into the atmosphere and (4) bio logical and chemical degradation. The information obtained from the monitoring of bomb fallout radionuclides is relevant to the present problem because like PCB, they are delivered to the ocean from the atmosphere, can exist in dissolved and particulate phases, and experienced a similar decreased input after the nuclear test ban agreements of Table 2 PCB concentrations in North Atlantic subsurface waters*, 1973 Date of collection Position and analyses! Latitude Longitude Depth PCB (m) (ngl-) 19/9/73 09 00'N 40 00' W t2/10/73 32 25' N 70 20' W 10 100 200 400 500 700 1,000 2,000 3,000 10 100 300 600 900 5,100 4.3 2.0 1.4 1.1 1.3 1.5 1.0 2.1 1.0 0.6 0.8 0.9 0.5 1.9 0.4 * Reproducibility at the 0.5 ng 1_1 level was 40%. The blank was produced by recycling 401 of XAD-2 extracted seawater through the entire procedure and averaged 0.3 ng 1-I. t Method C was used. . 1963. For example, strontium-90 which is mainly in the dissolved state in seawater, required more than five years after the test ban treaty to decline to one-half the surface water concentrations of 1963 (ref. 7). Thus, depletion of dissolved PCB from the upper ocean by advection and diffusion seems too slow to explain the observed rate. The rate of PCB removal from the surface waters more closely resembles the behaviour of the plutonium nuclides 155_,40Pu which are believed to be associated with particulates*. The vertical distribution of plutonium isotopes in the Atlantic was best explained as being associated with particles falling at rates of 70-392 m yr_i. The well known affinity of PCB for solid surfaces suggests that adsorption on falling particles could be a major transfer mechanism. In fact, if 2x 10* tons or less of PCB has been transferred to the deep ocean each year (1970 was the peak production year) for the past 10-15 yr and was dispersed throughout the entire water column, the concentrations to 3,500 m would still be less than 2 ng l-.1. Two 1973 profiles of PCB in the water column are presented in Table 2. The profile at 40 OO'W was typical of eight other stations in the North African and Cape Verde Basins; in contrast, the station at 70* 20'W revealing very low PCB levels at the surface, was similar to nine other stations In the North American Basin the same year. _ We are, at present, unable to ascertain the relative importance of evaporative codistillation of PCB from the surface water or of biogcochcmical degradation. Either process could explain the lower surface water concentrations in the North American Basin. There is, as yet, no evidence of biological metabolism of PCB in the marine environment. ' We note the rapid response of the open-ocean mixed layer to the reduction of industrial discharges of PCB. Efforts to DSW 361806 STLCOPCB4098034 3e8 . < . ~.................. Nature Vol. 252 November 29 1914 determine the mcciwnism of this clnc( ^transfer process arc in progress. . . \ This work was supported by an NSF grant to the interna tional Decade of Ocean Exploration. " *" George R. Harvey . - WlUJAM G. SlEINHAVER ' ; V Helen P. Miklas." Woods Hole Oceanographic Institution, _...... .. .... *, Woods Hole, Massachusetts 02543 .* The purines, adci..J ~^1 guanine, and a substance resembling uracil have been delected in the Orgueil meteorite14. Xanthine, thymine, uracil and derivatives have also been obtained experi mentally by mimicking supposed prebiotic conditions4. This chemical route to certain non-protein amino acids described above would presumably give racemic mixtures Of both stereoisomers, for example, both D-, and L-0-aminoisobutyric acid, as found in meteorites1. It would be interesting to know if thymine, dihydrothymine, uracil and related com pounds, when heated under supposed prebiotic conditions, did ** Received June 27; revised July 15, 1974. . ; give traces of the 0-amino acids. ` Chem. Engng. A'cii j, July 20, 31 (1970). * O.E.C.D. Press Release, Paris, February 1, 1973. * Department ofBiochemistry, D. F. Evered * Harvey, G. R., Slclnhaucr, W. G., and Teal, J. M., Science, 180, 643-644 (1973). - 4 Bidlcman, T. F,, and Olncy, C. E,, Science, 183, 516-518 `(1974). 5 Harvey, G. R., and-Slcinhaucr, W. G., Atmos. Environ., 8,-.777-782 (1974). : Chelsea College, University of London, ' Manresa Road, Chelsea, London SW3 6LX, UK 4 Harvey, G. R., Miklas, H. P., Bowen, V. T., and Srdnhaucr, W. G.,J. Mar. ties., 32, 103-118 (1974). ./ Received July 4, 1974. T Bowen, V. T.. Nosb[kin, V. E., Volchok, H. L., and Sugihara, T. T., Science, 164, 82J--287 (19G9). .2 * Noshkin, V. E., and Bowen, V. T., in Radioactive Contamination of the Marine Envifonment, 671-686 (IAEA, Vienna, 1973). Origin proposed for non-protein amintracids iq meteorites ;; ^ The amino acids that have been identified in several meteorites1-* can be divided into'two classes: those present in proteins and those which arc not. The presence of the non-protein amino acids, i>- and L-0-aminoisobutyric acid and 0-alanine, is described as evidence for the indigenous origin of meteorite amino acids and against terrestrial contamination1. It is implied that these 0-amino" acids arise by prebiotic condensation of ammonia, methane!,' hydrogen, water and other simple prim ordial molecules'. T^he 0-amino acids and other amino acids can ' * Lawless, J. G., Kvcnvoldcn, K. A., Peterson, E., Ponnamperuma, C., and Moore, C., Science, 173, 626 (1971). 1 Lawless, J. G., Kvcnvoldcn, K. A., Peterson, E., Ponnamperuma, C., and Jaroscwick, E., Nature, 236, 66 (1972). * Miller, S. L., Science, 117, 528 (1953). 4 Anders, E^ Hayalsu, R., and Studicr, M. H., Science, 182, 781 (1973). 3 Lawless, J. G., and Boynton, C. D., Nature, 243, 405 (1973). 4 Crumplcr, H. R., Dent, C. E., Harris, H., and Wcstall, R. G., Nature, 167, 307 (1951). 7 Asen, S., Thompson, J. F., Morris, C. J., and Irreverre, F., J. biol. Chem., 234, 343 (1959). * Campbell, J. W,, Biol. Bull., 119, 75 (I960). * Awapara, J., and Allen, K., Science, 130, 1250 (1959). 10 Evered, D. F., Comp. Biochcm. Physiol., 23, 163 (1967). 11 Block, W. D., and Hubbard, R. W., Archs Biochcm. Biophys., 96, 557(1962). 11 Awapara, J., and Shullenbergcr, C. C., Clin. Chim. Acta, 2, 119 (1957). . 13 Fink, K., Henderson, R. N., and Fink, R. M., J. biol. Chem., 197, 441 (1957). 14 Gartlcr, S. M., Archs Biochem. Biophys., 80, 400 (1959). 15 Cannclakis, E. S., J. biol. Chem., 221, 315 (1956). ' 14 Hayatsu, R., Science, 146, 1291 (1964). arise from simple molecules by Fischcr-Tropsch synthesis in the laboratory. Hydrogen, carbon dioxide and ammonia were heated to high temperatures in the presence of natural catalysts expected to be present in the solar nebula4. ._ In other experiments, thermal synthesis of amino acids occurred in a sirqulated primitive atmosphere of methane, Evidence Tor downwind flights by host-seeking mosquitoes ammonia and water, followed by acid hydrolysis of the products. Tjte behaviour of flying "insects which make use of airborne 0-Alanine was obtained in high yield, relative to other, amino chcmicals in their search for food, oviposition sites or sexual adds, and the straight-chain compound, 0-amino-n-butyric - partners can be separated into two phases, the search flight add'. These amino'acids were postulated to arise respectively bringing them into contact with the attractant plume and the from hydrolysis of-0-aminopropionitrile and the nitfjle inter approach flight leading them to its source1,1. The second phase mediate arising from addition of ammonia to crotononitrile. is characterised by upwind orientation in response to the Evidence for this route was the identification of succinic acid appropriate chemical stimuli'"*. Mosquitoes are known to fly and N-mcthyl-0-ala'ninc which arc likely hydrolysis products of upwind as they approach a warm-blooded host7-*. For most nitrile intermediates. Production of 0-aminoisobutyric fltid was not reported in these experiments*. insects relatively little is known of the pattern of the preceding search flight which Haskell' described as `wandering', but where 0-Aminoisobu(yric acid is a rare amino acid with a-curious the wind is light it may be upwind1. Experiments in West Africa distribution in natitre. It has been isolated only from human have shown that the majority of mosquitoes entered flight traps urine*, iris bulbs', flatworms* and edible mussels*.`.Man is from the downwind side, that is they appeared to have been probably, the only mammalian species to excrete d-(--)(t-amino- flying upwind, regardless of the presence or absence of a isobutyric acid1* though there is chromatographic evidence for host (ref. 10 and W. F. Snow, unpublished). Here we report its presence in rabbit urine". Metabolic experiments suggest that experiments that unexpectedly provide evidence for the opposite the pyrimidine bast thymine, from nucleic acid catabolism, is type of behaviour. the precursor of 0-aminoisobutyric acid in the human1*'14. , If the search flight is in a generally upwind direction, it Similarly, metabolic production of 0-atanine in rat liver is from - -should be possible to divert mosquitoes round a host by setting the pyrimidine uracil1*. . up a barrier on the downwind side and so provide a measure of .By analogy wilfv'these known reaction sequences catalysed protection from their attacks. The barrier would, need to be biologically, I suggest that heterocyclic compounds coaid also sufficiently far away for the mosquitoes to encounter it before act as precursors for the 0-amino acids found in meteorites. In they detected the presence of the host. So that directed responses this ease, scission of the ring of heterocyclic compounda'formcd : towards the host would not be elicited. This distance was prebiotically -would' occur under the catalytic conditions of estimated by. Gillies and Wilkes" to be less than 18 m for a extremes of temperature and radiation thought to occurjd space. host the size of a man. A host stationed at this distance upwind * *1 -' ................... " " \' DSW 361807 T t I ! i i Si STLCOPCB4098035