Document bRr5Mn2a0YwzRgOMex89nJw3

igcT 8/16/79 FYI M. Klaus F. Provorny <1. Ortii J. Weber G. Young Polychlorinated Biphenyls and Chlorinated Pesticides in Soils of the Everglades National Park and Adjacent Agricultural Areas AM* CL R*gu*|o*Richard H. Wm(, Patrick G. Hatcher, and Philip A. McGlUvary HiMowl Oceanic and Atmospheric Administration, Atlantic Ocaanographie & MetoorotogicaJ Laboratory*. Ocaaa Chamtohy Laboratory, Mtemi. Fla. 33149 808 aampln collected from the aaatarn Evargladas Natioael Phrk aad adjacant farmlands m analysed for main Meriaated pesticides and polychlorinated biphenyls (PCBs). The mulls Indicate that althoufh concentrationa of PCBs, 14*l`tricbloro-2^-biB<p-chk>rophenyl)ethane (DDT), and Mmdaaa arc high at the agricultural sites, little contamina tion afparkland* has occurred. Pesticide concentrations desetae* by twu orders of magnitude <to unit parts per billion levels) within 3 km of the agricultural sites sampled. Indi*. vWaal contributions of four Aroclors (1242, 1243,1254, and UWj,tabulated using pattern recognition techniques,suggest' tiMftphntic sheeting used in agricultural fields ie a local eourct ifPC8s. A comparison of the results to those from other envimnatnU reveals that PCB and DDT concentrations (bund vfcMa the Park (<1.0-33 and <1.0-22 ppb, respectively) are OS law aa any site in North America. The Everglades National Park m South Florida is a unique, dsBcately balanced ecosystem. Within the last 30 years, lands adjacent to the southeastern boundary of the park have been salenaively rock plowed and drained for farming. This agri cultural activity has grown and currently accounts for a sig nificant portion of the United States winter vegetable crop. The encroachment of man upon this wilderness has resulted In the introduction of industrial chemicals and pesticides, which threaten the environmental quality of pristine land* ta the west The National Park Service, in an effort to miniatiae contamination of parkland*, obtained an indefinite moratorium on farming in an area known as "Hole-in-the Donut", located within the boundaries of the park. The moratorium was the result of a study which found elevated levels of l,l,l-trichlorw24l-bi*(pflilm|hri)l)nhinc(l)iyr>, DDT awtahultlee, and dirldrin in soils and biota south of Hob-la-lbc-Donut" (/). A monitoring program conducted by the UJS.U-S. has found increaucd level* of DDT and DDT metabidifes in submerged anils cElected from nrarliy Taylor fihmgh (2). Although domestic use of DDT was Umnrd in 1972, the quantities used ami tIn* persistence of l)J ) l* drgradatioa products contimie to make these computiml* envifunmrnlally hazurthats. Other chlorinated jtcstivideH, such aarhlsrdane ami toxa|dwnr, are still studied to voriou* crofts. Chronic Inputs nf these pesticide* to the park via irrigation runoff or carrkw appliv;il s*n ctaihl hove a iliNOirHhp|f t H wiklttfc, especially Its* diverse avian |*ojmlutin (* 5). In addlihm to pvstirMlc*, imlusirial chemicals which may Pwseat aUim, University of Mhsdr Island, tlrarhutc Sthd fOvrimsgraphy, Kingston, H I trJWI, be affecting this region include polychlorinated biphanyts (PCBs), of which the toxicity and persistence have been widely rametched (6-10). PCBs have been uaed aa plasticisers m a variety ofcommercial plastics (/ /), and are suspected present in plastic sheeting voted by farmers to aid teed gemmation (I). The sheeting (or mulching) also reduces the frequency of ir rigation by preventing evaporation, and substantially im proves crop yields. Following use. it is routinely burned and plowed into the toil, thereby releasing any PCBa pismut in the plastic matrix into the atmosphere. Ones airborna, these compounds can be transported by wind into the adjacent parkland*. Because of the environmental and legal tmpticatioas in volved in determining whether the Everglades National Park is being contaminated by these anthropogenic pollutants, a study was undertaken to analyte soil samples from a south eastern section of the park, as well as samples of plastic sheeting obtained from local sources. The study area encom passed Taylor Slough, a major conduit of freshwater into the park, and adjacent agricultural lands. This paper proems the results of this study. Experimental Sampling. Samples were collected at sites along the southeastern boundary of the pork aa shown in Figure 1. Tho sampling grid was closely spaced in order to detect any horisontal gradients of agricultural chemicals in the area. Sites included both active (A) and A3) and fallow (A3) agricultural lands, recently farmed lands (1.3,4, and 6), and locations la TaylorSlough and smith and west ofContext Road. All sam pling was done in May 1976 in order to facilitate collection, as many of the locations sampled within the park are covered with, water during the.summer and early fall. Surface soil samples were collected using a Tefkm scoop to remove approximately the upper 2 cm of soiL Nonrrpresentntive surfai'e drlirw (leaves, roots, etc.) was removed prior ta fotlei'thm. Samples were plared in denned giro* jars and sealed with Teflon-lined mp*. Upon return to Ihe laboratory, all samples were immediately fnara. 17>ey were subsequently freeze-dried and stored frown for bier analysis. Analysis. A weighed portion of tho freexr-drird sod waa extracted with hexane in a Snxhlcl apparatus for 21 k SaINinification 4 raiulom samples tn determine extraction ef* firirtH'y dvmnl this procedure to lie greater than (V* ettWient fw rhkain.iled hydrocarlums. However, this eflicienry ran vary with the chemical nmiKsitkm nf the soil. An aliquot of the hexane extract was concent rated ta near dryness using a rotary rva|*tralor anti transferred onto a fukinrn ol Flurixit deorthnteti with T* wnler. 17a? nduam waa > TNS arttekr not sublet to U S. Copyright ruhSslieU 1919 AoMskon ChomtctS Society HONS 015187 Volume 13. HwnDef 9. AopiM 1979 931 bittd wquentiallY with hexane. 6% diethyl ether/hexane (rAi and MT* diethyl ethcr/hexane {v/v). 1*he 6 and SOT# ttWr/bexawe frarliona were concent rated in preparation for analytk by (tan ehromatocraphy. In order to w|Mriite 1*CB fnm l)l)T and DDT metabolite*. the hexane fraction wna WfWonwtlyntpbd on :r;deactivatedtalkie acid 112.I'D. 'Hw ttdnma wm eluted with hrunr followed l>v benzene. Thue harticon were eioolarly emwent rated for pa* chromatographic natyvk The nepatol im noheme in detailed in Figure 2. Hecorny ofstandard mixture* averaged HO-W'r. No mrmiion* lor recovery were atqdicd to the result*. PCIW were extracted with hrxane from plastic sheeting following treatment with bailing sulfuric acid. The hexane extract was analyzed using (be procedure described above. Chlorinated hydmntrlmn* were chromningrn|>hrri and fMRlilaled using a Trnrnr WiO gas chromatograph npiipftnl with a **Ni electron-capture detector. Peak arm were mea sured liy a Hewlett-Packard TWOA recording integrator. Three different column parking* were lined: glass roltMMift 12 m X 2 mm i.d.) packed wit It fi% 0V>210 on IOtVl20me*hSuprlroport were used primarily for quantitation of pwtindw while rohimm parked with I.%.9^*Sl'^WI and l%SK*!HVli% ()K-I, both on 100/120 mesh Supelwpurt, were lined for lH'lt (in.il>vk Pesticide concent rat inn* were ralculaled using external standard lit hnitjm**. Total DOT ami total chlordanr values were re|toried m the sum rf DDT* (pjj'-DD'r, u,p'-l)UT), DDT mclahuliteH (/,/' DDK, o.p*-l)l)K, pjj-DIM), njr'1)1 >l. ami the y ami isttnters of chlordanr. mqmrtivrK. Total |H'*ltcidrconcrnlrnlimis less than l.0ppbwrre ma re ported. IVIl ronrrntralion* were aliui ralculaled using extrrnnl * e--.1.. Mil C^Uaa X TixhiyJfww HONS 015188 Tall* L Ctdactaated Hydrocarbon Coocawbattona In Sod Samplot from lha Everglades National Park and M)>conl Areas <119/9 Dry Weight) Site, TaUl Mor4ww ToUl 00T TsUl K f Arsclsr 1242/1249 f Arwclsr 1204/1040 7frrkUrl M mmt111 M((Mo.(IftunnettUte)eeorrrrwwwMriillllyyyy)))g,':: mN <<<<11111....,40999 <7031<<<<1101111....9009 41H1411309.1 44499--7114392 I032T14900 t1rIMHHS11I12o10lf?0*a.f.*`v.t.t... <<44411J111.......00.41000l . <<<4<4111111........00740000 211I042I11(0....0799 44412-....0o300 <42131.....04700 410222....1477 997079710244249 0 000 wtr ntw ,* 1MI1lcCe 2212i.....1079i , 211027....7720 - n114122..11 to 1--004 teotent fcW tM? cQ0C0t-hM4-11) ` o4 <<<<4311111.......0440000 <<<4427111.......0010000 9i1i32S947....O107 009tIt$Soo4229 'AflOwbbmwOW'etasrty 1009s. Fw9 kspa aapr^ilmaaaly 1073. * Wo wtWn N bowery Ptfwpwfc N212O044091 100 N1100O00 10 . N1a0-O-0t a14MO91900S standarrir howsvsr, mdtvidusl contributions of four Aroctors (1143, IMS, 12M, and 12G0), which accounted for the majority ofdomestic ow from 1997 to 1971 (//>, were calculated mini; a computerised pattern recognition program (15). Pattern matchings of PCD* isolated from soil* are reported os percent Aroribr 1342/1248 and Arodor 1254/lJtW. These percentages represent approximate pattern matchings and are ws quan titative estimate* ofthe I'CttcomimmtionofrJt'h jutmfde. The detection limit was 0.1 ppli. Since 1*01 pattern rrviTgmtbm program* had not hern widely applied to environmental eamflrr. it was difficult to tawem whether this lerhath|ur nsild ha useful In determining sources and transport pathway* of these compinmds. West ft al. </n*l have used an idemleal program to characterize sources of sewage material in New York Bight sediments with limited success. Jtewdfr and tXstu$*itm Pesticide*. Chinrdnne. OUT, amt OUT metalmtile* sere the peineipai pr*tiride* rlctctird. Hcshlue* trf tdhef chlnriMded and ncgnnnplwsqihatc itcstwidc* examined in this ..Italy were present at only I luce sites tAI. A3. ami 'JiU. *1 he result* are summarized in 'Fables I ami II. AgrieulMir.il -in-* Al ami A3 were highest In total OUT ami MalchlunliHc. iViadcd application historic* of these fields wen* mg available: how ever, the l>UT metalsdite />./>* DDK accounted for a major partiua of total I HIT. indicating a Uk of recent use. The detection of aldrin and dieldrin at site A2 indicates a recent application, as aldrin is quickly oxidized to dieldrin in tails 1/7). J<ow level* of tola) t-blonhmeand lota] DDT at agricul' tural sties 1,3,4, ami li can be explained by the fact that these are very recently farmed areas (ca. 1973) and. thus, have re ceived little application of these compound*. In addition, these fit-ids lire cultivated only in the winter and left fallow the re mainder of (Ik* year. This is in contrast to active agricultural sites At nod A3, which are farmed must of the year. Lower levels f these rmnpmmdK at the fallow agricultural site (A3) suggest it has lirett inactive for some time. Nearly all sites proximate to the agricultural lands con tained pcsthkh- emM'eiHratNms Udow the detection limits of the analysis tTnhW-s I and II). (.'onceolrntion* of total DOT drop from Till pph (site Ai) to < 1.0 1.2 j>pb (sites 14 and IS. res|H*etivelv) over a distance nf slightly murr than 2 km. The same is true of chkwdanc which falls from 190 In 1.5-3.1 ppb at tin* same wire This drastic decrease in ronreniratinw suggests that little htwi/ontal tmnrment of pcsIiridrK has mvurred Tin- highest i-om ehtralitms of total DDT ami total thhiril.me within the |mck are found *11 Taylor Shmgh. Kfc- VHlvtl tsHH eitlralHms in the Sknigh wmiM hr iiwltr- athr of a mapit pathway for these com|MMtml* into the purk, .e., irans|Hrtet| lv tlte shiTtwaier flow either wlsorhed on (Kirthxilate matter or in tlie dissolved (those. Although higher titan in tin* surrounding sn-ns, the extremely hmr levels dr* HONS 015189 Volume 13 NimSmw ft Aiwwwt tftTft ass TaMa *. Occarrtnc* ol 01ha PasUcMaa In SoH iMflM Warn Uw EmglAdti National Park and Ann MmMNMadnyiHa ROW WMld ll any till oonoMlrstlofW |miv tfwn 1.0 ppb dbtsctsd al tm silos: 20.20 ppb; Al. 10 Mb; A3,230 ppb WOCbdXcwiW: A3,11 ppb MW dbWdod 1 any Mo nons detected al any she' mm dsfctsd at any aba* * *1--puns h a swipin mUMs o cNemane tompwmdb snd mey be dSSwSPdblscm On pwbsecb of eewr cNwUeisd eesbcidss. Low inM pi aopMapbaopbaia paaacwaa cannot bo Mcooiii Mbniwid wk^ m Mbabanaapbac dmcm. Tab* K tndhlduel Afoctor Distributions In Plastic Mwatog and ttta Sampling Grid (Parcon* of Total) , "w *S? *3ST <im pm PlinnQ --P-OPW 14 *< 10 * 17 10 11 21 lotted ladkata that thorn ora not Mendicant procaaaea. It 00ran thol ocricnltural activity adjacent to tha park ra- pmaMa for only knr-lcvtl cootemination of parklancb thoaofkTaylor Slouch. Bacauaaoftha importanco ofTaylor BonfklowiiciKft in tha Evttfladta, hnraver, pollutant WvaW In thla oraa ahould ba carafully monitorad. . Tha War lavab detected at thaae aitea a aurpriainf con- aUottaf thaW protimity to active atrkulturai fitIda. Factor! odrich maid account for thaao low conctntrotiona induda the hSsvisga * U The application of fertflixars, pesticides, etc., is confined lethe field* with litlk accidental application to surrounding A) CimIiC-11] nd L3IW tbRtMparatitlMii'Kultural kadi from parkland* arc receiving most of the irrigation end rainwater runoff. (c) Many toil samples contained relatively large amounts if srgpde MUsr. Humic substances, the msjor organic ssmpM*n( ofboik end wdimentJi, hsw been dioim to adsorb Ap'aDDT (11) and other hydrophobic organic compounds IflLIP)* Tha amounts of chlorinated hydrocarbons bound in tflaiw manner, and, thus, not extractable by organic solvent, aauhl be slgndWant. However, the ovwilobility of humic bound chlorinated hydrocarbons to bfotugicaJ systems has not been Figure 2. Separation teheme lor cMorlnalad hyppenboa analysts ofsotlsampiss documented. (d) The Ugh rale of evaporation and interne heat in the dry eaaon coukl account for km of even moderately volatile or unstable components. Further investigation is necessary to detarmina which of these factors, if any, is prevalent. PCBs. Agricultural sites Al and A2 are highest m total PCB, but concentrations are an order of magnitude Ism than the chlorinated pesticides (Table I). This is expected, as thousands of pounds of the pesticide DDT were used smuaiy in South Florida (2/), whereas pbntk sheeting, the suspected source of PCBs. is s relatively new item m agriculture. Con centrations at these sites are only slightly greater than at other sites in the grid. PCBs apparently are not accumulated pref erentially In farmland soils. A westerly decrease in concen tration is also observed for PCBs, but is more gradual than that of the pesticides. In some areas, such os the transect through sites 3-4-5 and CR-5-CR-3-CR-J-CR-0, leveb ini tially decrease and then increase away from the agricultural lands (Figure 1 and Table I). These increases may reflect al ternate point source* of PCBs or physical differences in ac cumulative tendencies among the different mils. The wide spread distribution of PCBs throughout the grid implies that ToMs IV. PCB and DOT Conconlrotton* In Various 6oHt and Marino Sodhnowts throughout North America and Bio North Atlantic ilWSlMllil pel *a*mn-e--m..e^- ^em. cno- n- .rec ^uy, awaa. ho| agrtevOwsf itWit western Canada hNMiihihplDeSa hat images poynwoi aoonac soytsai pwm MNMhaiCMi MCkaaaaaakeBa, **<*"*&* BN ivergMss NaSbnW Park nwecn,w 1S0-2.1 X 10* 05-1400 0.2-35 <3-15 M-I.I 10-3000 11-1300 M3 <1.0-33 mu aor.iww 750-4010 <0.1-130 02-13 <03-1.5 M <1.0-373 175* <1.0-33 mwee 35 3S 37 35 35 90 91 . IP Ns study *Asw'40t 4 *p*4)0D. * ss amMs tePnew; se soi. . HONS 015X90 I if f dispersal of these cnmpMinda b not limited by physical beuwderba such as canals or slough*. Tbuasperate analyse* of plastic sheeting for PCfb averaged tTS ppb Although the sab of PCtie was voluntarily limited It dosed systems after 1970, it b probable that materiab MUWn| PCIb were marketed and sold after thb date. The beds detected in the sheeting, however, are indicative of eaatembetbin during the manufacture rather than deliberate famudatinD. In spite of these trace levels, the individual Arecbrdistribution in plastic sheeting closely resembles the Aradur distribution in the templing grid; Le., if l*CBs bolated bam aN aampbs were combined, the pattern wuold be similar lathat of plastic sheeting (Table III). These data suggest that pbsllc sheeting is the source meterial in thb area. The indi vidual Arodor distribution in soil samples supports thb asartian. A pattern timibr to a mixture of Arodor 1242 and 1241 b found almost exdusively west-southwest of the isnabads end, to a lesser degree, in the Context Road area, sUr Arodvrs ISM and 1260 predominate south of the bmbndsand in Taylor Slough. In addition, the average PCB lamsatftwaw in the arete where Arodor 1242/1248 predaminate are nearly twice the concentrations where Arodor 1284/1210 predominate (Tabb 1). Ont explanation for these mpa) distributions b the different volatilities of individual chbrohiphenyb. The major chbrobiphenyb in Arodor 1248/1248. which have vapor presaum an order of magnitude greater than those of Arodor 1254/1260 (22, 2J), would he mere easily volatilised during burning and, thus, more susseptHih to aerial transport. The eeet-southeast winds which ptevB during most of the year (24) would account for the. ubarveddistribution and the westerly concentration decrease. DWbrtncss in average PCB concentrations can be explained by the bet that PCBe in plastic sheeting combi of nearly twice much Arodor 1242/1248as Arodor 1254/1280 (Tabb 111). Tha predominance of Arodor 1254/1260 in Taylor Slough hapfcts that transport of these chbrobiphenyb occurs by an alternate mechanism, probably adsorption on particulate MUar, which b deposited and resuspended in tha slough. SampKng of atmospheric particulates and vobtibs. especially during the burning of plastic sheeting, should determine the uaRdky of thb atmospheric transport mechanism. The data presented above suggest that vobtib PCBs are being mobilised by the burning of plastic sheeting and linspseteri by the prevailing winds. Thus, the levefa detected tetbeparkarepmfaridylhe result of tow level inputs occurring during the burning of contaminated sheeting. However, based an the magnitude uf these lcveb, thb input accounts for little contamination of Portlands. A comparison of the data in thb study la other areas (Tabb IV) shows that PCB and DDT levels blmd within the pork arc as low seat any site sampled In North America. Comparisons of thb type ran I* mblemling due to differing analytical techniques, but it b surprising to find lower levels of these compounds in the pork, a region periaHy suareptihb to direct inputs, than in coastal de positions! environments which receive indirect inputs (via acdimeatlng particulate matter, sludge dumping, etc.). Al though data presented herein indicate that the area b pristine With respect to chlorinated hydrmurUms, bvrb of other mdiutanlm such ss phlhnlate esters and polycyclic aromatic hydrocarbons, as well as other insect bides ami herbicides, shrqifrt be determined in mler to more accurately assess man's impart an thb fragile environment. Acknm'h'dumvnt* The authors thank Mike Macau for assblniwe with tlse analyses snd Adriana Cantiiio and Ktulip Hanson lor weir assistance with the sampling. Special thanks go to Georgs Harvey for hb helpful suggestions and review of the maim script 1Tie cooperation of the National Barit Service during the sampling period b greatly appreciated. Literature Cited (1) Hilacnheck, C. ft, "A Summary of Informstbw Absn Synthetic Agricultural Chemicals With Reference to Their Presence m (he Hofe-m-lheDomit and Taylor Siouxh, Kvcrgbdes Netbeal Bark* Internal HvfM*t. Keseerch bivtsioa. Everglade* Notional Park, Hommteed, Fin., 197$, (2) Kdipbki, M. C.. Higer, A. L Yates, K L, Pniit. Uonit. /. A 281-8(197)). (3) Hickey, J. J., Anderson. D. W., Science. 1(2.271-30968). (4) Porter. R.D .Wiemeyer.S. K, Science. 165, 199-200(1969). (5) Hsegele, M. H.. Tucket, R. K., Butt. Environ. Cantem. Toxical. 11,98-102(1974). (6) Duke. T. W,, Uwe. J.!., Wihon. A. J. Bull Environ. Conlom Taircaf., 5, 171-80(1970). (7) HaAer. M. T.. Johmon, H. ft./ Fith. Mom. BovHCon. 21, 1543-7 (1974). (8) Aulerkh, R. J.. Ringer. R. K., Iwamoto, 8. J., /. ttrprad. feHif., Suppt., 11, .765-76 (1973). (9) Tumesonb. C. F.. Bmh. B.. Reker. F. D.. Arch. Environ. ClUsa. Tvxicnt., 1,312-24(1973). (10) Hna,W..Ruebruugh,R.W., Soutar, A., Young, D. It, Science, 184,1197-9(1974). () 1) Peakelt, D. B.. Lincer. J. L. BioScitnee. 28,958-81(1970). (12) Armour, J. Bwkt, 4. A., / toot Off. 4as(. Ckm. IX 7VI-4 (1970). (13) Maaumoto, H. T., / Amoc. Off. AnnL Cheats U, 1092-7 (1972). (14) Interdepartmental Task Force on PCS*. "PCBs aad the Bsvl ronmtoi", NTIS, COM-72-10419,1972. (15) Zobel. M. G. R., / Amoc. Off. Aim/. Cheat.. 87,791-5 (1974). (18) West, R. H., Hatcher, P. G., Atwood. D. IC "Polychlorinated Biphenyls and DIXTs in Sediments and Sewage Sludge of the New York Bight", NOAA-EKL Data Report, In pew. (17) Lichtenstein, ft P^ Schulz. K.Rh 4. con. EntomoL, 82,118-24 (1968). (18) Pisrce. It H.. Obey, C. ft, Pelbeck. G. T., Gwrtet Cienchim. Acre. 1061-73 0 974). (19) Ogner, G., Schnitwr, M., Gcachim. Cosmarhim. Acta, 34,921-8 (1970). (20) Khan, S. SchnitMr, M., Geoch/m. Cvomochim. Acts, 96, 745-54 09721. (2!) Higer.A. UKolipimhi.M.C.-Source*o/Pesticides Florida Waters'*. USGS Open File Report 70005,1970. (22) Macfcay, D.. Wo/koff, A. W.. Environ. Sci. TtcknoL. 7,611-4 (1973). (23) Spencer, W. F.,Clbth,M. M.,/ Agrie. FeedCkem., 28,645-9 (1972). (24) "l^ncul Climatohvieal Data. Miami. Florida". U5. Department of Commerce, National Climatic Center. A*hrvilir. N.C.. 1976. (25) Stratton, C. L, Soeebee, J. B.. Environ. Sci. TechnvL. 10, 1229-33 0976). (26) Head. W. K.. MrKereher. R. Can. / Sait Sci. 81,423-30 0971). (27) (ibm.C.S..Chan.H.S..Neff.C.S.,Atbe,R.L., Science, 191, 419-21 (1978). (28) Dawson. It., Riley, J. P-, E*(uorine Cotuial Atmr. Sri., 4,85-60 09771. 129) Hnrvry. C>. R., Rleinhaurr, W. C.. in MKnrinmmenfa) Down chemistry", 3. 0. Nriugn. Kl.. Ann Arbor Science, Am Arbor, Mirh.. 1976. pp 203-21. CM) llaWrow, W,, M* Kay. 0. W.. Hogan. J.. Afar. PvBut. Butt , 8, l:lt 60974). (3|| I'sliwf. It. D., Tnm. K.T. S..Strain. A.."Transport ofChlort. nnteil I lyilrts-nrhnns in Setlinunis of thr l 'pprr Chtwipealw Hay", Tow*! |Kr|mrrti t'.o itw-t)ui>,4 W^ter Hr*owrt-r Rrrrrk, WrsliitglsiUKr (kenn Rtwenrch lathoratory, Aaitap>hs. 5M., 1976. _ firmtvrf /or rniVa* Amnnt ;t), |57d. Acrr|8n/ March H. IOTP. Tfc tttnly ra.< iip/>ocfrr/ b\ Ihr iStrk Svrrur. Ihpmrtmrnt of the bu rn*. umU r Vimtrort t\. 5297-/0118-/82. HONS 015191 Volume 13. Number 9. Aunust 1979 936