Document 3JgnbkvxknOQ0b1Rr95wkYbkO

. Nullin' Voi iS2 November 29 1974 0 J. A. M- M. Kors J. F. v,o. VATE JA^O 1975 L. T. Mf Humans G. DllUUTS Stichtin/; Reactor Centrum Nederland, ttoofifkantoor-SeltemnnusHrg 112. t' 'S'dromdinnefOndenoekeentrum: Pettrn (N-H)J The Netherlands Rereivrd June 28yrcvivcd August 28, 1974. * Voencta, H. A.. find Whitby. K T-. J. Colloid InteHaee Sei., 2S' SMI-57* 0967). * Stbfcr. W.. s/id Flachsbarl. H.. Ear. Sei. Techno!., 3, 1280-1296 . (i969>. ' * Wrick). N. r... J Utlnmnn. *<).. 24. 4M-4M (1*1). 4 Blither, \V., Flichubtrl, 11., and Hochraincr, D-, Staid/, 30,277-285 (1970). , Z * Blotter, W., in As%r.wnent of Airborne Particles (coil. by Mercer, Mwnw, and Slither), 249 (C, C Thomas. Springfield, 1972). * Drake. R. LI-in Topics in Current Aerosol Research (Porn) (edit. by liidy, arid Brock), 201, (Perganton, Oxford, 19T2). Decline of PCB concentrations in Norlli Atlantic surface water _ V.TCMUMnNFiiisNVL concentrations irTNtprth Atlantic iurfticc waters,have tlcriined fortyfold since 1972, following tha cessation of .Certain industrial uses of those Veompounds. Industrial sales of 1*011 for use in products whieh-would allow leakage to the-environment, for example in plaslfcs, Inks and paints were stopped in the United Slates and Sweden during 1970-71*; and`in 1972-75 other European countries and Japan initiated a similar action*. In 1971 and 1972 average surface concenlraiion^of PCB in the open North Atlani&.Ocean were about 30 ng (ref. 3 and C E. Olncy and J. J. Quinn, unpublished). $y April of 1973 the concentration in )tie Sargasso Sea had been ffcducod to I ng I"*1 (ref. 4); five months later we found that the`decline had levelled at 0.8ng a concentration Which was Stilt present in February 1974 in thi. north-west Atlantic. The accumulated data are presented in Tabic t. These Observations revealing a reduction in surface watdr concentra tions of PCD compare well with our February I0>4 measure ments of a tenfold decrease of PCD in the atmosphere over the north-west Atlantic since 1973 (ref. JK and a fivefold decrease Tabli 1 PCS concentrations in North Atlantic surface waters* 1971-74 J Data MeanPCBt fog I Sampling No. of Analytical) Raf. samples Method vn 29 Iceland to Nova Scotia rpi 41 , Ncwfoandiand to ;a I i vn 3ft Portugal ; 3 ^ % Norwegian Sea 11 m*m 301 Wood* I tele to Bermuda 27 Sargasso Sea I ;c ..-C r'A 3 3 4 W 2 Arnrcs to 00*N, 4tTW / i to B`arbad*os 0.1 r Sargasso Sea to IP ' C 3 * o New York flight 0.1 4 New llngland 3 i Continental Shelf .c 3 "OOftm. ' --------? 1 ftlank vcltws inr PCD in method* A. I) and C wert 0.9, 0.5 end M n* l respectively. Kcplicxte analyses ming (ikiImkIs ft or C Showed an nverape variation of t 20*/%*tthc I lion method* are presented in refs 3, 5. 6. level. Quentin. ) A, fixtractioh of 0.5- 3.8 t with chloroform or dicMrwnmrthane; , extraction of.70 I with 5% ether in hexane; C, pdNXtne 40-60 1 through Amberlltc XACN2 tesin followed by chilion-with boiling acetonitrile. IC. E. Olncy and J. J. Quinn, unpublished Information. . 3S7 since 1972 in . PCD content of mixed plankton collected along 09"N latitude in September of 1973 (ref. ft). The data require that about 2x 10* tons of PCI) were tost from the upper 200 in in less than one year*. To explain this loss, four processes must he seriously considered; (I) apparent dilution of dissolved PC'li by vertical and homontal sdvcction and diffusion; (2) association of PCD with sedimenting particles; (3) evaporative codisiiilatiou 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 atmosphere, can exist in dissolved and particulate phases, and experienced a simitar decreased input after the nuclear test ban agteements of Table 2 PCD concentrations In North Atlantic subsurface waters*, 1973 Dale ofcollection Position and analyses) Latitude Longitude Depth PCD <m) fog 1"') !9/9f73 09*00'N 40'OO'W mom 32* 29' N 70*M'W to1o0 200 400 300 700 1.000 2,000 3,000 to too 300 400 900 9.100 4.3 20 1.4 l.l 1.3 1.9 to 2.t 1.0 Oft 0.8 0.9 0.5 1.9 0.4 * Reproducibility at the 0.3 ne f level was 40%. The Wank was produced by recycling 401 of XAD-2 extracted seawaier through the entire procedure and averaged 0.3 ng t 1 Method C was used. 1963. For example, strontium-90 which is mainly in the dissolved stale 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, depiction 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 ***-*Pu 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 rales of 70-392 m yr~*. The well known affinity of PCB for solid surfaces suggests that adsorption on falling panicles could be a major transfer mechanism, in fact, if 2 x |0* tons or leu or PCB has been transferred to the deep ocean each year (1970 was the peak production year) for the past 10-1J yr and was dispersed throughout the entire water column, the concentrations to 3,500 m would still be less than 2 ng I'1. Two 1973 profiles of TCB in the water column arc 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 simitar to nine ether stations in the North American Basin the tame year. We are, at present, unable to ascertain the relative importance of evaporative codistillation of PCB from the surface water or of bingeochemical 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 10 the reduction of industrial discharges of PCD. Efforts to MOMS 0 6 6 4 8 0 MR . *,, ' . Nature Vol 252 N,nvemher 29 1974 dcl"ttninc the mcclymism of this etucient transfer process arc in propress. !' This work was supported by an NSF grant to the interna* tional Decade of Ocean Exploration. -' George R. HARvty y William G. Steinhaver Helen P. Miklas.* Woods Hole Oerondgraphie institution, '. Woods Hole, Massachusetts 02543 * Received June 27; revised July IS. 1974. *; ' Chem. Enem. Nri. July 20. 31 (1970). {. O.E.C.t). Press Hrkntc, Paris. February 1,1973. 1 Harvey. 0. K., Stefnhaucr, W. G., and Teal, J. M,, SrieOee, ISO, 643-644 (1973). -* 4 IMdkman, T. F.. arid Olncy, C. F... Sconce, 183, 516-511(1974). 1 Harvey, 0. K., and-Sleinhaucr, W. CAtmos. mwm^ 6. 777-712 0974). : 4 Harvey. 0. R.. Miklas. H. P,, Bowen. V. T.. and Sfldnhauer. W. O..J. AMr. rtr.r.. 32. 103-1IX (1974). .' * Bowen. V.T.. Noslikin. V. li.. Vokhok, II. L.and Sugihara.T.T.. Seiner, 164. 125 217 (1969). 4 Noshkin. V. L ,, and Bowen. V. T.. in Radiaoetier Cantooimotion of the Mmine /-Mfomtnt, 671-686 (IAEA. Vienna. 1973). Origin proposed for non-pro(cin amino'seids ip-meteorites 1 TM imtno.cidi IlMI have betn identified in .cveril meteorites'-1 ean be divided into'two classes: those present in protons and those which arc not. The presence of the non*protci ammo adds, D> and L>0**minoiiobutyric acid and 0-alanme, is described as evidence for the indigenous origin of mbteorite amino acids and against terrestrial contamination1. It is implied tint these 0-amino acids arise by prehiotic condensation of ammonia, methane; hydrogen, water and other simple prim* rdial molecules*. Tfic 0-amino acids and other amino acids can arise from simple rholecules by Fischcr-Tropsch synthesis in the laboratory. Hydrogen, carbon dioxide and ammonia were heated lo high lemhcratures m the presence of natural httalysu expected to be present in the solar nebula*. In other experiotents, thermal aynthesia of aminp acids occurred In a shnhlatcd primitive atmosphere of methane, ammonia and water, followed by add hydrolysis ofthe products. 0*Alanine was obtained in high yield, relative to other, ammo adds, and the itraight*chain compound, 0*amino*i^buiyrie add*. These ammo adds were postulated to arise respectively from hydrolysis of 0-amtnopropionitrile and the nitrile inter mediate arising from addition of ammonia lo crotoncmitrite. Evidence for this aoute was the identification of suednic acid and N-methyl'O-alahine which am likely hydrolysis products of Pitriie intermediate^ Production of (3*aminotsobutyricaNcid was not reported in tltcjc experiments*. 0*Aminoi*obutyric add is a rare amino add with a.curious distribution in nature. It has been isolated only from' -human urine*, iris bulbs*,-ftalworms* and edible mussels*.-.Man i* probably the only mammalian species to excrete cM-*)^*amino- laobtttyrte add1* thpugh there is chromatographic evidence for Its presence in rabbit urine". Metabolic experiments suggest that Ihe pyrimidine base thymine, from nudeic add catabolism, is fha precursor of 0-amlnoisobutyric add in ihe human1*'14. Shnilariy. metabolte production of 0-alanine in rat liver is from Ihe pyrimidine uracil'*. By analogy wilh^lhese known reaction sequences catalysed biologically, I sourest that heterocyclic compounds eriuld alio UCt as precursors for the |l*amino adds found In meteorites, in this case, idaskm of the ring of heterocyclic compoundaTarmod prebiotieally would' occur under the catalytic conditions of CklMnu oftemperature and radiation thought to oocuriospace. The purines, ode....... and guanine, and a substance resembling uracil have been detected in tfvc Otpucil meteorite". Xanthine, thymine, uracil and derivatives have also been obtained experi mentally by mimicking supposed prehiotic conditions*. This dtcmicAl route lo 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 meteorites'. It would be interesting to know if thymine, dihydrothymine, uracil and related coni* pounds, when heated under supposed prcbiotic conditions, did give traces of the 0-amino acids. - Department of Biochemistry, Chelsea College, University of London, Manresa Rood, Chelseo, London 5WJ 6LX, UK D. F. Evlred Received July 4, 1974. 1 Lawless, J. O., Kvcnvoldcn, K. A.. Peterson. E. Ponnamperuma, C. and Moore. C. Seiner. 173, 626 (1971). I lawless, J. G., Kvcnvoldcn, K. A., Pelvrson. K,, Ponnamperuma, C., and Jarrwewick. li-. Notyre, 236, 66 (1972). * Miller. S. L, Seiner, 117. 52X (1953). 4 Anders. E., Hayatsu. R., and Sludter, M. H., Seine*, It2, 711 (1973). * Lawless. J. G., and lloynion, C. !>., Nature, 243,405 (1973). 4 Grumpier, H. R.. Dent. C. E.. Harris. H., and Wvsiall, R. O . Nature, 167. 307(1951). * Asen, S., Thompson. J. F., Morris, C. J., and Irrevcrre, Fbtoi. Chem., 234, 343 (I9S9). Campbell. J. W.. BM. Ml.. 119, 75 (I960). * Awapara, J., and Allen, K., Seiner, 130, 1250 (1959). ' Evered, 6. F., Camp. Rioehem. Physiol,, 23, 163 (1967). II Block. W. D,, and Hubbard, R. W., Arehs Bioehem. Bbphja., 96, 557 (1962). 11 Awapara, J., and Shullenbcrger, C. C., Clin. Ckim. Acia, 2, 119 (1957). _ * Fink. X.. Henderson, R. N,, and Fink. R. M.. J. bbl. Chem., 197, 441 (I9S7). M Gariler, S. M., Arehs Bioehem. Riophys., 00,400 (1959). " Carmclakis. E S.. J. biol. Chem., 221. 313 (1936). 14 Hayatsu. R.. Science, 146, 1291 (1964). Evidence for downwind flights by host-seeking mosquitoes The behaviour of flying insects which make use of airborne chemicals in their search for food, ovipoiiiion 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 source1-*. The second phase is characterised by upwind orientation in response to the appropriate chemical stimuli***. Mosquitoes arc known lo fly upwind as they approach a warm-blooded host'-*. For most insects relatively little is known of five pattern of the preceding search flight which Haskell* described as `wandering*, but where the wind is light it may be upwind*. Experiments in West Africa have shown that the majority of mosquitoes entered flight traps from the downwind side, that is they appeared to have been -flying upwind, regardless of the presence or absence of a host (ref. 10 and W. F. Snow, unpublished). Here we report experiments that unexpectedly provide evidence for the opposite type of behaviour. If the search flight is in a generally upwind direction, it should be possible to divert mosquitoes round a host by setting Up a barrier on the downwind side and so provide a measure of protection from their attacks. The barrier would nred lo b sufficiently far away for the mosquitoes to encounter it before they detected Ihe presence of Ihe host, so that directed responses towards the host would not be elicited. This distance was estimated by Gillies and Wilkes" to be las than 18 m for a host the size of a man. A host stationed at this distance upwind 6 B V 9 B 0 SNOW