Document baY8xy4gmyExaEM2aKp6VMyEZ

Saltoe V<'l- $52November 29 " _ JAW 1975 1974 .. / J. A. M-'. M. Kops J. I". v:d. Vate kT4""'"" Stichtin.i: Reactor Centrum Nederland, . Haofdtantnnr.'Srhrveninftsn'en 112. t 'S-GrtncnlinpcjOndrrsoch centrum: retten (N-ll).J The Netherlands * : * Received June 28; revisedAugust 2Rt 1974. 'V- 1 .* 1 Vomila. R. A'., and Whit by, K. T., J. Colloid Interface Sci., 2S' 368-576 (1967). 1 SliiK-r, W,, nfid I'lachsbart, H., Btv. Sci. Techno!., 3. 1280-1296 (1969). r ". Wriplcy. N. G., J. Vhrastruet. Res., 24, 454-464 (I9'6R). . 4 Sliilu-r. \V., l laclisbart, I I., and Hoclirainer, 1)., Slaah, 30. 277-285 387 since 1972 in (lie PCD content of mixed plankton collected along 09'N latitude in September of 1971 (ref. 6). The data require that about 2 x 10' tons of PCU were lost from the upper 200 in in less than one ycar\ To explain this loss, four processes must he seriously considered; (I) apparent ^"dilution of dissolved PCU by vertical and horizontal ndvcction and diffusion; (2) association of PCU 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 PCD, they arc delivered to the ocean from the ntntosphcrc. can exist in dissolved and particulate phases, and experienced a similar decreased input after the nuclear lest ban agreements of * Sibber, W., in Assessment of Airborne radicles (curt, by Mercer, Morrow. and Xlobcr), 249 (C. C. Thomas, Springfield. 1972). * Drake, R. L.,'in Topics in Current Aerosol Research {Tort;) (edit, by llidy, arid llrock), 201, (Pcrgamcrn, Oxford, 1972). Table 2 PCU concentrations in North Atlantic subsurface waters*, 1973 Date of collection Position and analyses! Latitude Longitude Depth PCII (m) (ng 1'') Decline of'PCB conccnlralions ;. in North Atlantic surface walcr PoLYCiiLOiwnipiicNvi. (Pen) conccnlralions In Nbrth Atlantic tutfacc waters,have declined fortyfold since 1972, following the cessation of .dcrtaln industrial uses of those ^compounds. Industrial sales or PCD for use in products which would allow leakage to thc-Cnvironmcnt, for example in plastits, inks and paints were slopped in the Uniled Stales and Sweden during 1970-7M; and'in 1972-72 other European countries and Japan initialed a similar nction*. In 1971 and 1972 average surface concent rat ions_or PCI) in the open North Allantit.Occan were about 30 ng |-J (ref. 3 and C. E. Olncy and J. J. Quinn, unpublished), (ly April of 1973 the concentration in (he Sargasso Sea had been reduced to I ng 1_1 (ref. 4); five months later we found that (he decline had levelled at 0.8 ng I a concentration which was still present in February 1974 in the, north-west Atlantic. The accumulated data arc presented in Table I. These observations revealing a reduction in surface wate'r concentra tions of PCD compare well with our February 19*74 measure ments of a (enfold decrease of PCB in the atmosphere over the north-west Atomic since 1973 (ref. 5), and a fivefold decrease Table 1 TCB concentrations in North Attantic surface waters* 1971-74 : Date Mean PCBf (ng 1 "'X Sampling region ' '`1 No. of Analyticalf Rcr. samples rrlethod 8/71 25 Iceland to Nova Scotia 8 7/72 41 h Newfoundland to ;a 1 t Portugnl 8/72 36 Portugal lo 8 B 3/ i* Norwegian Sea 11 9/72 30 *. Woods 1 lolc to Bermuda 27 4/73 1 Sargasso Sea 8 9/73 2 i Arorcs l n 09"N, 40'W f to Barbados m .c ,,-c ,A *r 3 3 4 3 9/73 08 r Sargasso Sea to <* . New York flight 2/74 OS ( New England 9 c3 ; Continental Shelf 6 ,c 3 * 0-30 m. 1 DInnk values-for PCI) in methods A, I) and C wert 0.9, 0.5 and 0.3 ng I `, respectively. Replicate analyses using methods It nr C showed an average variation oF| 20% at die I ng I 1 Icy'cl. Quantita tion methods ate presented in refs 3. 5, 6. ' I A, Extraction of 0.5-3,8 I with chloroform, or dichloromcthnnc; B. extraction of.20 I with 5% ether in hexane; C, passing 40-60,1 through Ambcrlltc XAD-2 resin followed by elution-witli boiling acetonitrile. '< f C. E. Olneyand J. J. Quinn, unpublished information. 19/9/73 09" 00' N 40" 00' W 2/10/73 32" 25' N 70" 20' W 10 100 200 400 300 700 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 06 0.8 0.9 0.5 1.9 0.4 * Reproducibility at the 0.5 ng I level was -) 40%. The blank was produced by recycling 40 1 of XAD-2 extracted seawater through the entire procedure and averaged 0.3 ng 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 advcction and diffusion seems too slow to explain the observed rate. The rate of PCD removal from the surface waters more closely resembles the behaviour of the plutonium nuclides which arc 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 vr The well known affinity of PCD for solid surfaces suggests that adsorption on falling particles couIcT be a major transfer mechanism. In fact, if 2x 10* tons or less of PCU has been tranSfcrrtfif 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 1_1. Two 1973 profiles of PCD in the water column arc presented in Table 2. The profile t 40" 00'W was typical of eight other stations in the North African tind 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 codlstillation 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 ycl, no evidence of biological metabolism of PCB in the marine enviFonment. ' '--Wtnrote me rapid response of the open-ocean mixed layer to the reduction of industrial discharges of PC0. Efforts to DSM 026362 STLCOPCB4010323 w* ' Nature Vtd. 252 Nnvnnhcr 29 1974 determine the mecfianism of this efficient transfer process arc In prepress. . This work was supported by an NSF grant to the interna tional Decode of Orrenn Exploration. George R. Harsxev William G. Steini'iaver Helen P. Miklas.' Woods Hole Oeronogrophic Institution, ' Woods Hole, Massachusetts 02543 Received June 27; revised July 15, 1974. * Chem. Lnpny. Nrvf, July 20, 3) (1970). * O.E.C.D. Press Release, Paris, February I, 1973. * Harvey, 0. R,, Stefnhauer, W. G., and Teal, J. M., Science, 180, 643-6-14 (1973). . * Didlrman, T. F., and Olncy, C. E., Science, 183, 516-518 (1974). * Harvey, Cl. R., and-Sieinhaucr, W. G., Atmos. Environ., 8,- 777-782 (1974). ' * Harvey. O- R , Miklas. H. P.. Dowen, V. T., and Sreinhaucr, W. G., 3. Mar. Rrs., 32, 103-118 (1974). 1 Dowen. V. T.. Noshkin, V. l-,, Volchok, II. L.. and Supihara.T. T.. Science, 164, 825 -2K7 (1969). ' Noshkin, V. F... and Bowen, V. T., in Radioactive Contamination of the Marine Environment, 671-686 (IAEA, Vienna, J9733. I ........................-....... .I-- .1 I I) I Origin proposed for non-protein - aniino ncids in meteorites The amino acids (hat have been identified in several meteorites''' can be divided into'.two classes: those present in prolt/ns and those which arc not. The presence of the non-proteio amino acids, D- and L-|$-ammoisobu(yric acid and (5-alanine, is described as evidence for the indigenous origin of mfctcorile amino acids and against terrestrial contamination'. It is .implied thal these (5-aminni acids arise by probiotic condensation of ammonia, methand; hydrogen, water and other simplb prim ordial molecules'. T^e fl-amino acids and other amino acids can arise from simple molecules by Fischcr-Tropsch synthesis in the laboratory. Hydrogen, carbon dioxide and ammonia were healed to high temperatures in the presence of natural catalysts expected to be present in the solar nebula'. - In other experiments, thermal synthesis of amino acids occurred in a simulated primitive atmosphere of methane, ammonia and water, followed by acid hydrolysis of the products. (5-Alanine was obtained in high yield, relative to othicr. amino acids, and the straight-chain compound, P-amino-n-butyric acid*. These amino'acids were postulated to arise respectively from hydrolysis of P-aminopropionitriie and the nitrjlc inter mediate arising from addition of ammonia to crotorumitrile. Evidence for (his come was (he identification of succinic acid and N-nicthyl-P-alanine which arc likely hydrolysis products of nitrile Intermediate}. Production or(5-nniinoisobulyric gtid was not reported in these experiments*. p-Aminoisobutyric acid is a rare amino acid with a curious distribution in nalliirc. It has been isolated only from-human urine*, iris bulbs', flatworms* and edible mussels'.-.Man is probably (he only mammalian species to excrete tK-)f-amino- isobuiyric acid" tlvpugh there is chromatographic evidence for Its presence In rabbit urine". Metabolic experiments suggest thal the pyrimidine base thymine, from nucleic acid catabolism, is the precursor of P-nminoisobulyric acid in the human1*''*. Similarly, mctabolig production of P-alaninc in rat liver is from the pyrimidine uracil'*. By analogy witlvjHcse known reaction sequences catalysed biologically, I suggest that heterocyclic compounds could also ad as precursors for the P-amino acids found in meteorites. In this case, scission of the ring of heterocyclic compoundlformcd preblotically would' occur under the catalytic conditions of extremes of temperature and radiation thought lo occur.ih space. Tlw purines, adenine mid guanine, and u snhst.mcc resembling uracil have been detected in the Orpucil meteorite". Xanthine, thymine, uracil and derivatives have also been obtained experi mentally by mimicking supposed prchiotic conditions*. Tftis chemical route to certain non-protein amino acids described above would presumably give racemic mixtures of both stereoisomers, for example, both D-, and L-p-aminoisobuiyric acid, as found in meteorites'. It would be interesting to know if thymine, dihydrothyminc, uracil and related com pounds, when heated under supposed probiotic conditions, did give traces of the P-amino acids. , -> Department of Biochemistry, Chelsea College, University of London, Manrtsa Road, Chelsea, London SW3 6LX, UK D, F. Evcred ' Received July 4, 1974. ' Lawless. J. G., Kvenvolden, K. A.. Peterson, E., Ponnampecuma, C., and Moore, C., Science. I7J, 626 (1971). ' Lawless, J. G., Kvenvolden, K. A., Peterson, E., Ponnamperuma, C., and Jaroscwick. C,, Nature, 236, 66 (1972). ' Miller, S. 1.., Science, 1 17, 528 (1953). ' Anders, u., Hayatsu, R., and Svudicr, M. II., Science. 182, 781 (1973). * Lawless, J. G., and lloyntnn, C. D., Nature, 243, 405 (1973). `Crumplcr, It. R.. Dent. C. E., Harris, H., and Westall, R. G., Nature, 167, 307 (1951). ' Asen, S., Thompson. J. f\. Morris. C. J , and Irrcvcrrc, F., ). blot. Client., 234, 343 (1959). ' Campbell, J. W., Dial. Bull.. 119, 75 (I960). * Awapnra, J.. and Allen, K.. Setrnre, 130, 1250 (1959) 10 Uvered, D. F., Comp. Binehem. Physiol., 23, 163 (1967). " Block, W. D., and Hubbard, R. W,, Archs Biochem. Biophvs., 96, 557 (1962). " Awapara, J., and Shullcnberger, C. C., Clin. Chim. Acta, 1, 119 (1957). " Tink, K , Henderson, P-. N.. and Fink, R. M . J. biol. Chem., 197, 441 (1957). " Gartlcr, S. M.. Archs Bfochem. Biaphys., 80, 400 (1959). " Cannclakis, E. S , J. biol. Chem., 221, 315 (1956). " Hayatsu, R,, Science. 146, 1291 (1964). Evidence for dotvmviiid flights by host-seeking mosquitoes The behaviour of flying insccls which make use of airborne chemicals in (heir search for food, oviposilion sites or sexual partners can be separated into two phases, the search flight bringing them into contact with the attractant plume and the approach flight leading them to its source''1, The second phase is characterised by upwind orientation in response to the appropriate chemical stimuli1'*. Mosquitoes arc known to fly upwind as they approach a warm-blooded host' "*. For most insects relatively little is known of the pattern of the preceding search flight which I laskcll'described as 'wandering', but where the wind is light it may be upwind'. Experiments in West Africa have shown thal lire majority of mosquitoes entered flight traps from the downwind side, thill is they appeared lo have been flying upwind, regardless of the presence or absence of a hosl (reF 10 and W. F. Snow, unpublished). Here we report expcrimcnls that unexpectedly provide evidence for the opposite type or behaviour. If the search flight is in a generally upwind direction, it should l>c possible to divert mosquitoes round a hosl by setting up a barrier on the downwind side and so provide a measure of protection from their attacks. The barrier would need lo be sufficiently far away for Ihc mosquitoes to encounter it before they detected the presence of the host, so thal directed responses towards the host would not be elicited. This distance was estimated by Gillies and Wilkes" to be less than 18 m for a host (he sire of a man. A host stationed at this distance upwind DSM 0 2 6 3 6 3 STLCOPCB4010324