Document 0JEOxyQY47Z2NVJd351VZoNMR

Nfvrmher 29 /Q74 J. A. M. M. Ron J. F. v.o. Vate L. T. M. Hixmans C. Dinarrs Sinhtinv Knittiu Centrum Nrth'riund, HtH'Ulkunhnn St hi vvntnuswvf! 112, `S-Ittun tilMue. (huktMiekwntrum. Pcitcn (N-H), The W ihei Itnhl*1' Received June 2K. wd August 28, 1974 1 Vonwlu, K A., uml Whitby, K. T., J. Culloui Interface See, 15' V>8 57t. (1967) * Sluhei, \V,, .uni I I.khsbart, II.. T.ttv. Sri. Teehno!.. J, 1280-1296 <19691. * Wilkie), N. ( . J. (i/trmtruri Mrs., 24, 454-464 (1968). * Blotter, W., Huclixhiiil, 11., wrul Hoclujiikt, D., Sinnh, 30, 277-28$ (1970). * SIhIht, W., m Axirxtmrnt of Airborne Porlielri (edit, by Mercer, Mourns, uiul Mattel l, 249 (C. C. Tlwmttt*, Springfield. 1972). * Drake, It 1, in Jtipui in l urrent Aeiostil Research (Parti) (edit. hy llid.s. iiiul brink). 201, (I'orcamon, Oxford, 1972). Decline o/l'ClI.Xonccnfrations in Nor!!: AThnitie surface water Tim w iii <>m>;tnu!i nvi. (PC'll) concentrations in North Atlantic w w, i,,*i> i .ivt- declined forty i'tiicl since 1972. following the ccv..iiii'ii oi vi'iiain industrial uses of those compounds. liiilt!.l: :ii '..) o' TCH foi i:,-.e m I'liidovls which would allow ! -t ui. J u cv.ri;\\: in plastics, inks and partis is etc stopped in ihc Uniu-d States and Sweden during l'1 "! ;v. -r. ')) other * nro;v 'it countries and Japan unit.:Uu a stiTi .ii cuitoitv In 19/1 a,ul 1972 average surface tom ablations of TCI) in Ihc open North Atlantic Ocean were about It) iv I 1 (icf. .1 and C. L. Olncy and J. J. Quinn, uiipuhlislK-d). iiyApiilof )9/Jthc concentration in the Sargasso Sea had been reduced to I ng I ' (ref. 4); five months later we louml that die decline hud levelled at U.H ng I ', a concentration which was still present in 1`cbruary 1974 in the north-west Atlantic. Hie aiuirmilnlcd data arc presented in Table I. These ohseivatmns revealing a reduction in surface water concentra tions of K I) compare well with our February 1974 measure ments of u tenfold decrease of PCB in the atmosphere over the north-west Atlantic since 197.1 (ref. 5), and a fivefold decrease `JaMr I I'CD cniucntuimns in North Atlantic surface waters* 1971-74 Duic Mruu PC1I1 <Mg I ') Sampling region No. of Analytical! Ref. sample* method 8/71 Iceland to Nova Scolw 8 7/72 Newlitondland to Portugal 8 Portugal to Norwegian Sea )I 9/72 Ml Woods Hole to Bermuda 27 4/7) 1 Sargasso Sea 8 9/7.1 2 A/nieslotW N.40'W to Barbados 9/71 OH Satgussn Sea to 10 New York Bight 2/74 0.8 New t-.ngtand 9 Continental Shelf 6 0 30 m 1 Blank values for PCH in methods A, B and C were 0.9. 0.S and 0.) ng I ie\|H-uivc)y. Replicate analyses using methods U or C xliowedanavctiigevarialionof .1 20%al the I ngl 1 level. QuanlilaInmi metiMtds n prvscntcd in refs 3, 5, 6. 1 A, Esitnciion of 0.5 3.8 I with chloroform or dicMoromtthanc; B. exI raction of 201 with 5% ether in hexane; C. passing 40-60 I humph Ambcrliie XAD-2 resin followed by elution with boiling acetonitrile 1C. E, OIikv and J. J. Quinn, unpublished information. .* . uJL1H7 since 1972 in ihc PCI) content of mixed plankton collected along 09"N latitude in September of 1971 (ref. (>). The data require lhai about 2x 10* ions of l'( |) were Inst from the upper 200 m in less than one year1. To explain Um loss, four processes must be seriously considered: (l > apparent dilution of dissolved PCB by vertical and horizontal udvecnon and diffusion; (2) association of PCB with sedimenting panicles; (1) evaporative codistillaiion into the atmosphere and (4) bio logical and chemical degradation. The information obtained from the monitoring of bumh 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 TaMc 2 PCB concentrations in North Atlantic subsurface waters*. 1973 Date of collection Position and anaiyscst Latitude Longitude Dept )i PCB (m) (ng 1 19/9/73 09* 00' N 40*00' W 2/JO/73 32" 25` N 70` 20' W IU 100 200 400 too 7011 i non 2.000 3.000 10 :oo M<0 `AHi 5.I(H> 4.3 2.0 14 1.1 1.3 15 10 2.1 10 06 OH 09 05 1V 0 -i * Reproducibility at i!ic 0 $ ng l *' lcel was 40".. ] he blank was produced by recycling 40 I of XAD-2 extracted seawater through the entire procedure and averaged 0.3 ng 1 t Method C was used. 1963. For example, strontium-90 which is mainly inp the dissolved slate in seawater, required moic than five years after Use 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 rale 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 failing at rates of 70-392 m yr1. The well known affinity of PCB for solid surfaces suggests (hai adsorption on falling particles could be a major transfer mechanism. In fact, if 2 k 10* tons or less of PCD 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 I Two 1973 profiles of PCB in the water column are presented in Table 2. The profile at 40 00'W was typical of eight oilier stations in the North African and Cape Verde Basins; in contrast, the station at 70 20'W revealing very low PCD 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 codistillaiion of PCB from the surface water or of biogeochemical 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 (he rapid response of the open-ocean mixed layer to the reduction of industrial discharges of PCB. Efforts to MQNS 0 8 3 7 6 3 i Nutate Vot. 2*2 N<'\emhc, 2'/ ft? I dcu-iimuc Hie itwclumivm uf this cltieiem transfer process arc m pn|!it>N. lhi> wink wa*. supported by an NSF pram to tltc Interna tional Dcs-nlc of Lvploralion. GtoHCL R. Harvey Wii i.IAM G Stj inhaver I ll.i.t H P. MlKI.AS Woods Hole Orriiiiuci./phir Institution, H'otuii I lolf, Mu\.\ochu\cttx t/2.W.f Received June 27; icviwil July 15. IS>74. * Chem I nnK M m , July 20, 31 (1970). * O.L.C.D. 1'rrn Release, Pans. February I. 1973. * Harvey, O. R.. Slcmluucr. W. G-. and Teal, J. M.. Scirnrr, ISO, M3 644 (1973). * flulleman. T. F.. ami (>lm\v, C. 1;., Science, 183, 316 518 (1974). * liar voy, (I R,, uml Sumliaucr, W. G., Amw*. Environ., 8, 777-782 (197-1). * llarvcv. C\ R MiU.a, l! P, Howcn. V. T., and Xteinhauw, W. (5 ,,J. hUtr. ti< \.. 32. 103-118 (197.1). 7 Douvn. \' T . Nosliku;. V. I'., Volrttuk, 11. 1... am] Sugihara, T. T.. Sruucc. 1*4. s:s 2N7 (19*9). * Nn.ihkm, V. 1 ., .mil llouvit. V T.. in Hudionrnve (ontnnnnatum of th, M.4WIC i.itviumtmiii, *7|-b8* (IALA, Vienna, 1973). O.V.iv 1':- non-protein .tur- ; f':> . i "'<ioritcs i in ..mi . ..i. i-ls .1'. n 1. >..; nlcoinicd m .-oveial inetcomes1* can be divided into two classes; those present in proteins and tliotc ..;t i *i. 'll-.- ;';.-.eiv.v oT the acti-prolein amino I.-. ......... i .ii.T.id'Miiyiic acid and |)-jlanmc. is Ucundxrd as cvulcruc lor the indigenous oripin of meteorite up) mo acids .' .>1 ;.;,i,i.v 1tcsirml Cwiitam.;.at ion1, It is implied that these ll*nmino uuds arise by prcbionc condensation or ammnitm, methane. hydrogen, water and other simple prim ordial molecules*. The fl-antmo acids and other amino acids can arise (rum simple molecules by Fischer-Tropsch synthesis in the laboratory. Hydrosen, carbon dioxide and ammonia were heated to high temperatures in the presence of natural catalysts expected to be present in the solar nebula*. In other experiments, thermal synthesis or amino acids occurred in a simulated primitive atmosphere of methane, ammonia and wutcr, followed by acid hydrolysis of the products. 0`Aluumt' whs obtained in high yield, relative to other amino acids, and the straight-chain compound, 0-amino-n-buiyric cul*. These Hmmo acids were postulated to arise respectively from hydrolysis of (Vammnpropionitrilc and the nitrile inter mediate arising from addition of ammonia to crotononitrilc. Evidence for this route was the idcmihcaiion of succinic acid and N-mcthyl-fl-aliimnc which arc likely hydrolysis products of nitrile intermediates. Production of 0-aminoisobutyric acid was not reported in these experiments*. 0-Ammoiobuiyric uckl is a rare amino acid with a curious distribution in nature. It has hern isolated only from human urine', iris bulbs7, lluiworms* and edible mussels*. Man is probably the only mummnlmn species to excrete i>-( )0-*mino- Isobutyric acid" though tlvcrc is chromatographic evidence for its pretence in rabbit imiiic". Metabolic experiments suggest that the pyrimidine base thymine, from nucleic acid catabolism, is the precursor of 0-aminoisobutyric acid in the human"*". Similarly, metabolic production of 0-alanine in rat liver is from the pyrimidine uracil". By analogy with tliese known reaction sequences catalyaed biologically, I suggest dun lieterocyclic compounds could also act as precursors for the 0-amino acids found in meteorite*. In this ease, scission of the ring of heterocyclic compounds formed pretnolically would occur under the catalytic condition* of extremes of temperature and radiation thought to occur in space. Tlxc purines, adenine uml guanine, and a substance icscmblmg urucil have been detected in the Orgucil meteorite" Xanthine, thymine, uracil and derivatives have also been obtained experi mentally by mimicking supposed prchiotic conditions* This chemical route to certain non-protein ammo acids described above would presumably give racemic mixtures of both stereoisomers, for example, both d*. and L-fl-aminoisobutyric acid, as found in meteorites1. It would be interesting to know if thymine, dihydrothymine, uracil and related com pounds, when heated under supposed prebiottc conditions, did give traces of the 0-amino acids. Department of Biochemistry, Chelsea College, University of London, Manreso Rood, Chelsea. London SW3 6LX, UK D 1 Evtato Received July 4. 1974. 1 Lawless. J. G.. Kvcnvoldcn, K. A., Peterson. F... Ponnaniprrunu. C, and Moore. C.. Science, 173, *26 (1971). 1 Lawless, J. G-, Kvcnvoldcn. K. A., Peterson, 1:.. I'unnampcrunm. C,, and Jaroscwick, L., Nature, 23, 66 (1972). * Miller, S. L., Science, 117, 528 (1953). 4 Anders, E.. Haynisu, R . and Siudier. M. H , Science, 1X2. 7K1 (1973). * Lawless, J. G., and Boynton, 13., Nature, 243, 405 (1973). * Grumpier, H. R . Dent. C. L-, Harris. H-. and Wcstall. K <j.. Nature, 167. 307 (1951). 7 Asen. S., Thompson. J I-., Morris, f. J., and im-verre, I-'.. J. hml Chem., 234, 343 (1959). * Campbell, J. W.. Biol. Hull., 119. 75 (I960). * Avapiurt, J . and Allen. K.. .Socwt, 13V, 1251) t ! >*'>> ,0 livcrcd, l>. I-., Comp, Hiochnn. /'Iiyuol., 23. 163 (!%7). 11 Block, W. D., and Hubbard, K. W., Arch* Hiochvm /////<. v . 9*. 557 (1%2). ** Awup.ira, J., and Shu)k*nbcrgi;r. C*. C., Uin. Umn. Acta, 2. 119 (1957). " Fink. K., Henderson, R. N.. and Fink. R. M ,J. bioi. Chem, 197. 441 (1957). ** Gartler, S. M., Arehs Binchrm Biophyt., 80, 400 (1959). " Cannelakis, E. S . J. hiol Chem., 221, 315 (1956) '* Hayatio, R . Science, 146, 1291 (1964). Evidence for downwind flights by host-seeking mosquitoes Tut behaviour of flying insects which make use of airborne chemicals in their search for food, oviposmon sites or sexual partners can be separated into two phases, the search flight bringing them into contact with the attraciant plume and the approach flight lending them to its source1,*. 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 Haskell* described as 'wandering'but w here the wind is light it muy be upwind1. 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 ot 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, u should be possible to divert mosquitoes round a host hy setting up a barrier on the downwind side and so provide a measure of protection from their attacks. The barrier would need to be sufficiently far away for the mosquitoes to encounter it before they detected the presence of the host, so that 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 the size of a man. A boat stationed at this distance upwind < r9 iS 9 0 SHOW