Document 7aVg6yoN5Nw0zZwpK17y3a6B

LEAD INDUSTRIES ASSOCIATION, INC. SSI MiOltON AVKNUI NEW YOU*. H. Y. 10Ot -- MIA CMI HI JC** f**Cl~KOH. MW *N*.*TW w OMtH. WM 'WOW O THAW**- rw Mwa> t. T**M. M MHWIwf x>ww c iw#*a*jrr I^ |rr I---1 M| I IMUMT r t . A tlWIMM a * - Vs*& !f#r,feS& Jaauary 11, 1967 Toi The lead Health aod Safety Conalttee Fl Paper given at the Aaerlcaa Association for the Mvsacant of Bclract sectleg 00 Deccafcer ?9 1966, at Washlsgtcc, D. C. A,5 trfc<J for your Ir.rrrxAt Sc<5 li a copy of paper eot it led "KIAYT-XETAl CGSCAXUSATIca Of SOILS* by Dr. Jobs V. lagerverff. This copy i obtained for us by Bill and Kaovltcc unofficially sod say hare scot cilUttl tad unclear passages. Please excuse. W are vrltlng to the author la aa atteopt to obtain a ccaplsts aad official copy of tbls paper. Of great interest to us are sane of the ctnseate that Dr. tagenserff aafcea about lead la that sect loo. Very truly yours. tCfisv attacteest A- i r i fser * ^`k'sO*. /I gpHB'jgr UMgAiilRawraillWMSWWIWM<WeiWXe^^ ' : '& CTIWW.J^LlgBMWMW^^ ^ . ' ' LIA11955 ^ "'" ;1 mvr-+tnxL c o j t iw c k at io b or soual/ Dr. John V. Lag*rvrff2/ Contamination of a coll occur* when foreign *ubetaoc** ar* intro* dueed into th* plow layer which adversely Affect the quantity or quality of crop* produced. The CcvlranoentAl Pollution Panel of the Pre*ld#nt's Science Mriiorjr Coemlttee, in a recent report (137), jh**led the health hatard* resulting froa heavy eetala entering the food cycle hy way of the soil. There are at least 5 Multiple source* of heavy Metals!/ that eay cause soil contaednatloo, *1*. aero* ole, peetlcldee, Hen too** sad pheephat**, iwag* sludges, and nine waste* (table 1)* t. i Asroaols derive Most of their heavy Metals free oxidation processes, s.g., gasoline coobuitloe, coal burning, aad o*tal eoeltlag. Contael nation aad local pollution of soils eay then occur when eseltlng pleats dally dl< chart* Into the atoo#ph#re 2 tone of lead, 8 too* of copper* aad 3 ton* of tlao, as reportedly occurred la Montane (6). Airborne eoc- teal pint* charged with heavy aetale nay decisively lnflusooe the heavy* natal exposition of such flow growing plant* a* lichen, which is tapl*food to reindeer, e nain constituent of the Kaklao diet (73# 7) In weighing the potential haiard even of eeenlngly Minute aaounta of tali, it la veil to rwasher that by passing through the coo#motion chain a*#ocl ated with plant and anlaal Ilf*, otherwise harmlse* oon* oeotratlone aay locreee* to Injurious levels ("biological Magnification*)* Contribution froa the U.0. Sol 1* Laboratory, Soli aad Water Conservation Research Division, AM, IF DA, Reltevllla, Maryland. To be presented at the flyeposiue on ^Agriculture and the C^jallty of Our forlrooaant," sponsored by Bsetlon 0 (Agriculture) of the American Aeioclatlon for the Advancement of {Vctenc* on December P9, 19^6 at Washington, D.C. To be publuhed la the Proceedings of that Bynpceite*. 7j Research Soil Scientist y The tern "heavy astale* ta this paper ha* been u#*4 broadly to include certain Metal* not foraally belonging to this group. (While the text give* reference# la par*nth###*, no list was attached.) N 463.01 fT" M5S*. >J,V Za vtw of currant lntaraat la accunulatloo, tra&alocation, and degradation of peatlcldea la toll* aad wtm, It la la ordar to nxantna tha baevy-netal eonpooeata of paatleldaa vlth raapact to their potential M envlrocnental pollutanta. Za a *rot9 of Bare than 20t> different peatlcldea 11a tad aa current la the Obitad State# (112), haary natala ooouiyad 111 tinea la 112 dlffaraat product* (Ha, Cu, 2d) Za, 2kf Cd, 13) Me, 12) Cr, 7) 8a, 3) , fa, 3) aad Ph, l). fltie la heoeueo la 29 eaaaa tvo aatal tpaclae vara praecnt la tba mm conpouod. Xetala Ilia ft, Cu, aad K* hare applied to aolla tinea loo* before tha edrunt of ehlorlaatad hydrocarbon# aftar tha Second World War. Za 196h, tha U.8. production of eoppar aulfata, laad araaoata, aad aarcury- eoetaialaf pee tl clda* aaowt to about hl.8, 9*0* *ad 1.6 *1111on Ibe, 1 me pact! rely. Tha application of llaaatooaa aad phoaphataa, or tbalr produeta, to aoil elmya lapUaa tha addition of aa array of haary natala. Tba altuatloo haa been exanlaed for rockjhoaphata (5V), tuperpfcoepfcatn (10, S3) aad Unaatoo# (l>9). Tha praaaooa of uranlu* la aaay phoaphato dapoalta (113) la laportaat beeeuee of tha anaulna radioactivity la plaata pan oa pbcepheto-fertlllred aoll (109). Thia leave vlll ha rafarrad to latar. Samoa alada, both actlratad aad dlfaatad, Uhavlaa la a pool of hoary natala (h). Za gaoaral, tha 1(0,000 odd tooa par day of toll4 vaataa produced Mtlooally hy urban coneualtlae (6l), eooatltuta a. rarltahla nine of haary natala. Tha 47icultural application of treated mat# natarlal, tharafora, oalla far cartful cheat cal araluatlon aid control (8). oil eoetantaatloa occur* la aiaia* araaa. Mttumlly, tha aoll near tha Klnln* oparatloa la cooUalneted aa a raault of tha dlapoaai of liquid or toll! mtlaa. Contanlnettcn of land hy tpoll tank draleef#, .i ~f -! ''!&%' 1 2? s- **Skt howvar, My involve larg* area*. Depending oa th* mineral* that are mined, the heavy-natal concentration of the** liquid vutM may W7 high Indeed (HO), m vlll to* diacusaed la paaatng. lb* follovlng natal* vlll to* a*mlp*d Individually: copp*r, alnc, aangan***, nickel, *1*1m, mercury, eadmlia, aad lead. Vto*r** th* oil ebanlatry of th* flr*t f m*t*la ha many characteristic* la oamoo, that pertaining to th* lattar 3 deviate* In Important respect*. Xa addition, hatarda associated vith mercury, eadalua aad l**d ar* far aar* serious than tho** typical of th* otb*r metals. toot eooaldr*d * ar* tin, vhlch rarely ccntanloat** soils, aad Iron, chrcnlua, aad cobalt, which ar* aot kacvm to contact oat* aolla, although th* latter tvo bar* often b**a ralatad to loll Infertility. Ia each caa, aviating Infor* ation ahall toa awnasrlMd on aourcea of ontealnation, occurrence aad availability Of th* nttal In th* aoll, and poMlble abatement program*. Natal concentration* In plant and aoll ajiociatcd vith toxicity syvytcna have been quoted la laolated lnataacee only, far each combination of variable#, theee criteria ar* mlqua aad of llttl* g*n*ral vain*. 3222 ttore* aourcea of cooteal nation vith Cm prevail, via.. Industrial dual* (by, 07), cffluanta from mines (bd), aad from acvag* treatment plant* (29), and eopp*r'Containing fungicId* apraya. The l*tt*r have teen particularly destaging in florid*'a a*ody eltrua belt (lb)), In vine-grovlag ar*aa la fraace and Italy. Old rlnayard* n*ar horde*ux, fraace, contained up to fib) ppm of total Cu lo the topaotl, 2% of vhlch va* considered achangeable (J7). Ttneyard* In the Alsac* reportedly contained up to bOO ppo of total Cm la tha topeoll (3). Apple orchard* 1 H3* - *jpnni -J In Xngland with a long copper-epray record contained nor* than 1500 pj In the surface net (78). Concentrations of copper In the oll which exceed 50 ppn nay already be barnful in florid* to citrus seedlings (lVl). Is the United 8t*t**, peetlcldee containing Cu nor noetly hold the natal In an organic, leea baneful fore. Copper often accvnmlatea in the top#oil (38, 78, lkk), strongly absorbed to allieste mineral surfaces (39, 111), or chelated by organic natter (l8, 00). Thus, Cu la rendered leea available to plants (98). ' Where the chelate Is soluble, however, It nay nova to the B-hcerlson (176). In spite of exhaustive leaching, not nora than 2% could b* removed fron C\fi0y applied at a rate af 90 lbe/ecre to eolusned soils (70). It follow* that surface-rooting crop# grown on certain orchard soils nay suffer severely. Clover and alfalfa are particularly sensitive to exoeaslvn snounts of Cu, but so are citrus seedlings. Stunted growth, ehlcrotle foliage and dieback nay result (lWl). In determining the equilibrium between the noblle, nonovalent, cuprous Iocs sad less mobile, dlrulent, cupric Ions, th* soil chemistry of ecpper Is lntlnately related to the acidity of the soil. 80II treat ments or cllmatlo conditions Increasing soil acidity to pH<7 favor th* cuprous form, thereby causing copper toxicity symptom* where previously there were coot. This nay partly be caused by s breakdown of the complex between Cu and organla natter as th* pH decrease* (kj). Such ooodjJ^loo* Kay coo* about by heavy application* of superphosphates (lhh, 157)# gypeiM (1)V), or R-ferttltier* (55) The application of phosphates, p*r < seems to have had little effect la euppreeetng the availability of Cu to plants (&) Neither did It looreas* the retention of Cu XA .) : 1 Ii In topeoil (1>5). Za order to Increase the oll pH, the toll bee been 4reiaed vlth line (13) or alkaline fertiliser* like potassium blcerbooete (Vj). Although thle trsatnsnt usually suppress## the uptake of Cu by plente, It felled to happen la atudle* vlth trefoil aad barley (133)* Ca 1* known to praeote the oxidation of ferrou* loo* to fsrrio loo*, thereby obstructing fe-tran*location, mad Inducing fs-chlorosl*, la aecy plmate (3d, 73). Za overcoalng tb* effect* of Cu-toxlcity, therefore, mppllemtloo of ft-XWH to *oll or foliage ha* eat vlth considerable sue#** (106, 133), Za the erne* of cltrue tree*, a do*age of one-quarter to 00*-half pound of Te-ZDTA pr tree, aad enough Ud * to rala* th* pH above 7, have ahevo good result* (160). Za turops, foliar application of fe-ZDlA la conjunction vlth lining (36)* mad th* ue* of such Cu-cc^laxing agent* a* CafOOj or j^fe(Ca)g (lV6) (?TT) have bees tested vlth good result* la over*oalng the edveree effect* due to costaalMtloa of solli vlth Ctt. tine 1b* following source* of so11-conteaalnation vlth Za preeellt aeveg* affluent* (9), Industrial vast** (69), particularly fro* nine* (7, lbfl), ruperphoephate* (Ufl) aad pesticide* (39)* A fev laetaaeee have beta reported of in-toxicity due to protective vlre caging around young tree* (66) or flax (117) Che latl co of Za by organic Better la th* topeoil, although $-* leaser degree than Cu (&>), ha* been repeatedly shown to occur (T7, ll6). Chelation a*/ render Za 1** available to plant*. Where the chelate 1* soluble, it say sore Vo the P-horlsvo (l?6), A correlation coefficient of fl.fll (l) has bean reported to xt*t between th* distribution of Za --Vv . J'- - r* t 7;- ' ; jjjjywii1 * ' Ifgg jjyg;ni.il.ywyjflygagry J* u* lot organic natter la a m*fc*r of aoll* (66). rurtberncr*, to, Ulc* Co, la atrocgly ateorted by allleate adnaral aurfac** (V?, 120). Vh*r* Za aceuanlat**, thanfora, aurface-rooting plant* Hi* nuatard auffer car* than d**p-rooting plant* lli* p**a (95) * tba pH of tba aoll lnflu*ac*a tb* atat* of oxidation of Za, a* v*U aa tb* aolutility of tba hydrcxid* aad of aeveral aalt* of Za. ttkla ralatlonahlp nay b* lialtad dot to organlo-natter ecaplaxlag of Za (21). Partly tecau** of tb* breakdown of organic Zn-chelate, taxlo ounta of Zo aay ba r*l*a*ed If tb* aoll pH d*cr*a**a (172). Ob tb* other hand, lacreaalag tb* aoll pH by tb* application of 11a* (151, 17^) or bydratad 11m (159)* atrongly counteract* tb* availability of Za to plant*. In bantacit*-clay eye tea*, Zn aolutility baa b*a oba*rv*d to reach a alnlear* la tb* pH<rang* of 6 to 8 (92). T*t, narf Uptake of tb* chela la, Zo-KDCt, va* observed at pH 7, which nay cbaractarla* a pbytlologlcal optima* (lfil). lb* poaalblllty of a reduction of Zo-toxlclty upon tb* appHoatlon of pboapbat* frrtlllirr* to tb* aoll vould follow fron may a report Involving a nuoter of crop* (JO, 101). Ho effect of pboephate application on Za-toxicity vaa ote*rv*d, however, vltb b*aaa (12). Ukevtee, heavy dr***tng* vltb euperphoepbate did not Influence tb* retention of Za in tb* topeoil (lhj). Zarller evidence indicated that Za 1* not nteetaarlly precipitated when pboapbat** are added to tb* aoll (66, 1)2) It haa hem pointed out vltb regard to loo-uptake by excleed barley roote^thet carpetltl on between Za and Ca, rather than precipitation of Za aa tb* phoepbate, *ay explain reduction to Zn-uptak* In tb* preaeoc* of ealcltaa pboapbat* (ljl). / -7- Xd ic m c u m, the possible effect of phosphate fertiliser* oa Zo-uptake lty veil have been obliterated by th* concentration In which thl* aetal occurred a* leparlty tn thee* fertiliser*. Value* u high as 1^30 pj*s En have been aeesured In superphosphate (id) and up to SfcOO In triple superphosphate (12). Rock phosphate* fro* th* Eastern IBA nay contain no nor* than about 150 ppa Enj but those fro* th* Western are* nay have a* Much as 1050 pp* (29) (cf. table 1). Superphosphate la Australia nay also contain large anouats of Zn (170, 126). Zo-toxlelty s yeptana appeared to be alleviated by enriching th* oil with Re-chelate (101), or the nutrient eolutlon with Cu-ealta (125). i The uae of Cu-ealte, like that of Ca-ealta, however, nay cauae F*-chlorosis, a haiard also brought about by Za Itself (20, lK). firon experiment* carried out In Florida (ll2) one nay deduce that orang* trees would be able to ovwrcon* toxic syaptana due to Zo by the application of I and K fertiliser* to the soil. In centrest, H-cootatnlng fertiliser* hav* also been observed to Increase the availability of Za (125). lb* natter, of course, strongly depends 00 accompanying changes In soil acidity. Manganese Reported Instances of ccotanlnatloo of soils with Mn are few. Mm seepage (l66), fly ash (lWO), >te-coctatnlng fertllltsrs (H5), and lnpur* phosphate fertiliser* (tl) were held responsible. Although Mn has occasionally been observed to scciseilat* In topeotle (to), It generally occur* throughout th* soil profile (176). Where eccuvulatloo occur*, chelation of Mn by organic taller (03), even Involving the aanganto Ion (67), nay be a poaatbla explanation. Chelation decrease* the availability of Ma (95). } f *& the behavior of Hn la the toll depends largely upon the relative equilibria* between the mobile, divalent Manganous and the leee aoblle, trlvalent aanganlo lone, this equilibria le datereined by c*lAatlco reductioa condition*, which any be cheelcal or biological by nature (107) and are related to the pH (127). free a eoll-pH of 6.5 on up, the oaciIliad fore generally prevails. Hore acid conditions proeote the occurrence of the reduced fore (17l). The amount of untractable Ko of 26 Louisiana oil* Increased 6-fold upon submergence (139). Manganous lone are readily evallable to pleats, whereas aangaalc lone are aot (153) Consequently, rcduclrg conditions auch aa generally exlat In poorly aerated eolla (17), aad such aa Bay exlit In tbe A0-horlioo of podtol and podtollc eolla (96), ay lead to aa Increase in >ta-uptake by plants. 0a the other hand, the asM# condition* also pronote lose of Nn by leaching (9). & Soils suffering from cootaalnatloo with Hn can b* readily reclaimed by Using (63, 65). On one occasion, Using s soli fro* pH h.5 to 6.5 reportedly decreased the exchangeable Ko by a factor of 20 to JO (?3). With cotton (l) aad beans (52) the problem could be controlled by Using the toll to s pit of only 5>*. Oa one occasion, a recuperative effect has been reported of with regard to Ka-toxlctty (1C*). Conflicting results have been obtained with regard to the effect vvl ,r`*r*. of phosphates on the availability of Mn to plants. Ob the one hand, reports dealing with pineapple (9J) *d tooatoee (97) Indicate that phosphate* tend to counteract effects due to toxic coocentratlon^%f / Hn. On the other hand, phosphates have been mentioned to stimulate the uptake of Hn by lsg\*lnous and noo*l*r*'lr*n* forage plants ()) aad oats (126), Application of superphosphate to soil cultures of lettuce Icwered the pH on an alkaline soil, leading to Increased uptake of Mb. Cm as eeld toil, however, the pH was raised, thereby reducing Ha-uptake (115). *1 i^l-^il\ZiP%JL' ` .' ",-.' ->f^tr J*p'"r*- ** * -~*~ ...."' - *'*'%. r v , `> ,, ' , .'. ". ' > *.. ' ' ' '.' , 7: .,; . t\& .<v,.-. 9- fh* oxidatloo-reductlon condition* that determine the e<jul llbrlvsa between Manganous sod Manganic Iona sre known to be subject to bacterial activity (60, 98). Micro biological oxtdatloa of aangsooue Iona has been obaerred {19). Talgatloo of soil# with 1,3-dlchloropropan* resulted In a decreaa# In Ha-uptake by Brussels sprouts (102). Btaaua-aterilltatloa (56, 113), as veil as drying (153) of soils, however, resulted la an Increased availability of Ma. Bacteria that oxidise Mo Increased in auaber when straw Mulch was added to a soil (l&) An exceea of Ms la known to cause fe-chloroels la plants (51, 12b). On the basis of this antagonistic relationship, the decrease la Ma-lajury can be explained following application of ft-aalt* to the root subetretee of tobacco (?b), rice (1*9)> sol red clover (65). Cobalt has bees Mentioned ae aa antidote to Ma la the case of toaatoee (2), and oats (57), but It nay cauee Fe-chlorosla by Itself (72). Michel Until recently, superphosphate coctatnlrg nickel lapuritlee appears to have been the only known cause of contamination of toll with this petal (5b). Currently, Ml has replaced Fb ae anti-knock agent In certain gasoline*. Aa plant* generally shew Much let* tolerance to Ml than to Ph (of. 72), this tread should be looked upon with due concern. It May be pointed out that Infertility dim to Ml 1* of concern la serpentine soils in Scotland ( lb7, kip 158), and la Southern Bhodeeta (6)). The Metal here occurs as a aattve constituent, soeettaes accoMpanled by ehrr*tu (lb7, 156). Vhereae Ml occur* throughout the profile In serpentine soils. Its presence la cert*la potaolle soils Is Hatted to the topeotl (bk), Tbs possibility of chelation by organic Matter has been auggeeted ()2). tv? / -js\ w'i'SsK-- tmturnitj it...mu lii ii mmmf *w* me i mv* ^itmf^gappa I LIA11964 . 7&*k k *j r < * ctsuj&s**,j v ..A. u*.. _ . - ,,~ "' ,, " "' ' . ' k :, ^ -i j.V.fik.'^ a*.*; aiawgJBa.*au. ** *!&& ' ` ........................................... -10- Btcauaa tba availability of W to plant* It lavertaly related to the pH of the toll, application of 11m bn* resulted la a reduction of toxic eyptoo* (25, 32). A 7c reduction la HI-uptake by tugmr baato rataltad vhan tba toll pH m ralttd from k.d to 6.3 by lining (fib). Addition of pboepbate to aolutlona containing IlClj bat baaa obeerved to dacraata algolfleaatly tba aolublllty of II at pH> 6.5 (136). On tba otbar hand, application of phoaphataa to Scottlth tarpaotloa toll# lacraaaad toxicity aynptone dut to II la tba caaa of oata (33). With toll coltura* of teoatoct, appllcatloo of pbotpbata fertiliser did not altar tba extant of Injury dut to II (121). Tba natter aay dapaod vary ouch on tba pH of tba ayatan. bacauaa II and fa art aonavhat anta^aciatle la tba autrltloo of cartala planta, tucb at barlay (}8), , appllcatloo of ft aay counteract n-toxlelty. Za fact, la tba prateact of officiant fa, a dacraata la pi raportadly atlnulatad tba uptake of fa by cate at tba expanta of It (31). tfbara lining la preferred, a*pactally la tba caaa of tarpaotlna tollt, attantloa abould be paid to tba Pe-outrltion of plaet* (169). AIx mI m** About tba only reported type of coetanlnatloa of toll with Al, outalde of alnlng arena, oceura baa cartala kind* of fly-aah tattle down (1V0). At weathering of tba tab proceed*, tba availability of Al aay dacraata by tba form*i100 of eryatallloa Ca-alualnata (91). Tba toxicity c^hfly-Mti i to planta hat al*o be*n aaorlbed to boron ratbar than Al ( 8l). lUtural Infertility of act! tollt dut to Al falla beyond tba teope of thtt paper. Boll anendsenta reccresended la tbta caaa, hovavar, thould ba applicable alao to aotla contan! n* tad vltb fly-aah. Pertinent literature la volutlooue. A--'*' ***V.' : r * y ^f-V '' ja^ nBr-'^rj; y^IM*5(PSWW ( LIA11965 B?WW'.'X ;.'. _ i J -/in'yJaS*- iV*ViWVTtV" i' >.!iii-nr 'iivr>'Srrnr -li ne rcury fungicides containing Kg nlourvl (112). They Kca to be tho only presently knevn source of contamination of soli vith Kg. Report* Indicate that Kg-containing paint*, used for their wood-preserving properties In greenhouse*, a#y constitute a entree of contamination vhen ventilation 1* Inadequate (k2). Under condltlona norxally prevailing In aclla. Kg la readily reduced to the Metallic fora, thereby disengaging Itself fron the original compound if the latter vere a slapla salt. Bo such behavior h*L* been reported for cotplex organic Hg-conpouad*. The toxic nature of Mercury vapor has locg been known (16). Potted rosea did not suffer any daeag* vben grown In toll treated vlth RgClj, and placed In a veil-ventilated greenhouse. Dasage did occur, however. In the absence of ventilation, O especially when the soil van nixed vlth tankage (IT?). The same vaa observed to happen vlth a variety of truck crop* (15)- In the ease of 10 plant species, lijCl-, alxcd vtth soil or Ians age that vaa placed In the 1 mediate envlroiwnt of, but not in contact vlth, these plants, caused f-i!'rr rttf^i of ft,; nnd reduction of growth, ho tranalocatloa of Kg vaa observed from the leaves to other plant parts (l?6). Kg did not seen to be taken 19 by the roots of plants fron soil treated vlth KgClj and tankage, The damage vaa Halted to the leaves (79)* Reports Indicate that the vapor* of Kg and KgCl^ affected the growth of rote* (1)6) and that of vheat, beans and lettuce (lk) in equal Measure la each case. As the vapor pressure of KgCl^ 1* significantly lover than the one of Metallic Kg, It Is likely that the chloride Malt indeed had broken down, releasing Metallic Kg. Deposited in the fora of spray or leaf litter, Kg occur* aoetly la th# topeoll. The only effective Measure against contan) nation of toll vith Kg see** to be the appllatloo of 11a* sulfur or of leaeotal tulfur. Sulfur and Kg react effectively la vapor fora (175). V-r> ' vi. ~ *-**, TUV--" J.i 1 .usng.sc.ww. . * w wgnwWnaWii.,n.*wmm 4 ^7-- LIA11966 * *" J-- ^'w *~*>y** -*-**--Tl-rl^H` 'if - T^:j ;.':' - T :i sjfiis*: W<: / o Cadalm Although then are no known ImUs c m of cooteesloetlco of soil with Cd, a few rcsartaregarding thle eventuality are la order. They are prompted by a recent report on relatively high atsoepherle concentration of Cd la 11 Eaatern U.8. cl tie* (2**), in conjunction vlth the known low retinaMan tolerance of Cd. The latter partly reault* frcn the lack of a honeoetatlo aechanlen, l.e. Cd la abeorbcd virtually Irreapectlve of the exit ting concentration In the body. It accunulatee In soft tlaauee, and caueee cardlo-veacular dlaturbaacea (30). Dlatrlbutloo of Cd la the ataoapbera occur* through proceeaee of aaaltlng, roneting, and plating of aeUi*. Cadalvia alao reache* the toll aa aa lapurlty In phoephatee (table l). It la uaually preeeat la aoft water flowing through welded pipe*. The natter la of concern to aoll cheat eta becauae Cd la known to be abeorbed readily by at leaat a mvber of planta auch aa alnt (62), vine (kj), lettuce, parenlpe, beete, peaa, and grain crop# (150). In the latter eaat, the concentretlooe raage fran k to lk pg per 100 g vet weight. There 1* oo known Information oo the aoll chealatry of cadalta. lead Prlae aourcea of aoll contael cation with fb are coebuetloa product* of leaded gaeoltne, liquid and vapor vaetee froa coal-burning and aetalrmltlrg eatabllahaeota, lead araenate peattcldea and phoephate fertlllaera. ( radioactive) lead naturally occur# a* a faally conatatlng of a auaber of labile/and a tabla laotopa*. The terminal part* of the thorlua and, a* peel ally, of the uranlw radioactive aerlee are of concern la the eaae of eotl* and plant*. In the ur*nt\j*-*#ri*, blaeuth, tellurlue and polootua (fo-210) are th leteraedlatea occurring In the tranaltton fro* radtoactlva lead (J>-310) to atable lead (lh-206). The tranaltton fro* Pb-210 to fo-210 1* accanpanlad by beta and gea radiation, wharea* fo-910 tranemutao to gf- `VA,-' r: K LIA11967 ' * t m ft'.:-- f ; # -13- Pb-206 producing alpha radiation (^6). Lead readily assimilates In the boo*, end polemics in the soft tissues (muscle, kidney, spleen) of the Eaunallan eyatea (76, 123). Car-exhaust fusee currently era the daslnaat source of soil contamination with Pb. Betvecn 1950 end 196h, the voluse of lead arsenate handled annually by agricultural cooperatives in the tfcltsd States dvindled froa 3d to 9 Billion lbs. In the aue period, the production of leaded gasoline almost doubled froa 3d to 70 blllloc gallons per year. Dus to the addition of Pb-tetraethyl or Ib-tetramethyl to gasoline, the radioactivity aay be ae high as 30 pc/gallocV (108). The amount of Pb discharged Into the ataoephere above the U.S. due to Motor vehlclee la 19^ amounted to 100,000 tone, or 10 of the total lead loJuatrlally consumed (l6l). It has here been assimed that the proportlooe of presivsi and regular gasoline are y$ and 7C^ of the total gasoline used. The average Pb-contents are taken to be 2.1 and 1.} g per gallon, respectively (11), vlth 7% of the lead never reechlng the ataoephere. In the entire northern hemisphere, the average annual Motor vehicle exhuestloo of lead Is setteeted to be about 260,000 tons. This estlnate is ccneervativs (cf. 1>0). The average atmospheric content of Pb for cities vlth a population <0.1, 1 to 2, and >2 million increases la ths seas order froa 1.3 to 2.0 end 2.9 ug/m^ of ground-level air (26). Current attempts st laprovlng the combustion of leaded gasoline may result la a decrease of the average particle site of serial lead compound*. Thus, the concentration of air-borne Pb, sad the contaminating capability t ths ataoephere vlth regard to this Metal, may increase. y pc* pieocurtea 10"M curlee9.22 atomic dee Integrations per at outs. t- w* r* LIA11968 Partially equilibrated mixtures consisting cxf Fb-210, Po-210 end $ lu.,.. F stable Fb eventually reach the surface of land and ocean by the precipitating action of mlcvtr, er>ov, or dusts of various kinds. The atcody Increase In the Fb-content of the air In the course of this century follows fro the fact that tha Pb-content of Greenland snow h&j rlan frcai 0.16 to 2.6 ug/llter between 190** and 19$* (119). A study of tha composition of snow In Lassen Volcanic Netlooel Parte, California, Indicates not only a hl(bcr content of lead than calculated oo the basis of currant lead-alkyl production la the northern heaisjhere, but alto an laotoplc eaxposltloo a leilar to that of Los Ancclea aeroaola. This composition, ' la turn. Is practically Identical to the one typical of regular gasoline (27). The Influence of motor vehicle exhaust la directly reflected In the ! lb-content of plants as a fuoctloo of urban proximity, or of distance from sod density of, traffic (table 2). Thus, the lb-content of trees (rodi| near the London, Kngland, metropolitan area was higher than that of tpeclsene growing the countryside by a factor of 7 for aah, 25 for oak, anl 26 for haxel (173)* Crass sampled as a function of distance from the t roadbed contained up to A times as much lb within 25 feet frcai traffic as that collected more than 500 feet away (22). The Fb-content of grass collected at the leeward side of a road was much higher than that of grass growing at the windward side (A7). An Increase In traffic density by a factor of 2 or 3 caused an Increase In the lb-content of the tope of roadside grass by a alatlar factor (9*>). When rye and potato plants growing within 15 feet of traffic vers eoapared with plants located more than 300 fsetaway, the fb-content* of kernel and tuber were Millar by a factor of about 2, but those of chaff and green tope war* about the ime la the case of each crop (100), Ocean contents of lead also appear to reflect the proximity of industrial establishments (l6j). ft*,. LI A11969 *sx"" ' 'u .wl i -15- Indication* hare been gathered In England that the radioactivity of great regained confined to the aerial part#, and that the fraction of the total Fb that voa radioactive Pb-210 vna 20 tlaee higher than It vaa In the aoll. Tbeae findings euggeet that Boat of the Pb-210 In thli *? grata originated fro* aerial aourcea. The Po-210 and Pb-210 apparently f vere depoelted on the grata blade* froa the air, rather than abeorbed by the plant# fro* the aoll and tranalocated to the bladea (75, 111), Under the high rainfall condition# prevailing In England, radioactivity of great aKiunt to 10 pc/g dry natter la reported not to be uncq--on (76), There are lndlcatlooe that gratae* would abaorb alpha-radioactive Po-210 with preference to beta-game-radioactive Pb-210 (62). The biological effectlvenee* of alpha-radiation la V tinea greater than that of gaieaa radiation (A6). K 9 The Buch dlacvnaed topic of coot**! nation of tot 1 with fh due to apreylng or due ting of plant* with FV-araeoate nuat renalo Halted to on* pertinent exaaple (90). Eight different plant spec lee were grown for 3 year* at rotation crop* co coaaerclal orchard aol 1> at h different location* In Oregon. Between plant* fron prayed and unaprayed *olla, the Pb-cootent* differed by a factor of 1.2 for the top*, 1.6 for the edit;* portico*, and 3.1 for the root*. It had been noted In what probably vaa ooe of th* earlleet * tulle* Involving th* biological uae of radio-taotope* (71) 3< that Pb, when abeorbed by the root#, tend# to accumulate In that plant part. ? 7he average uranl\a-content of U.9. phoepfate Aepoalta 1* e^ulvalent ; to O.li UjC^ (105). It foil*** that aotla dreeaed vlth phoephat* fertlllter* ay render plant* radioactive due to uptake of Pb-210 and fa-210. Thu*, th* radioactivity of th* boo** of eheep rateed on field* fertlllted with baalc flag vaa 255 of coaparabl* value* of antaala paalured on fields eupplied vt th euperphoephat* (109)< ' V" ~ i. '- ' . - - ' -d !^rygi*Mnegv3^v.te^;*^ttro:g^^ LIA11970 . t if Q m -16- Pb originating fran conta&lnetloa tend* to to retained In the topeoll. For example, the Fb-content of the A0*horlion vu 3-2 tlmee that In the A|-horltoo of eolla of the Charlotte-tcvn eerie*, and 9*1 tle that In the A*>-boritoo of toll* of the Aroad*le eerie* (176). (t) The poeilblllty of Pb-cbelatlon by organic natter eeesed/not likely In a etuly covering a variety of toll* (1^). It he* been *tgeet*d (f) (163) that precipitation of 1% and Pby due to organic natter la la*trveaental in fb-retention by the topeoll. Because of the surface sccuaulatloo, aurface*rootle plant* auch ae cover crop* arc affected to a greater extent than deep-rooting plant* auch ae orchard tree* (89). IMi nay pee* a pedal threat to llveatock that la kept on old orchard or potato land (103). The toxicity of lead to plant* ha* been related to the pH of the eoll (3^). The uptake of Fb by kidney beans has been counteracted by adding CaClj to culture aolvtloo* (133). In the caie of ltgune* growing 00 eolle adjacent to nine# la England, heavy dreealngs vith Use have been applied vlth good result* to counteract toxicity due to Fb (&). Concluding pcaarke The majority of the natal* dtecuaaed to thle preeentattoo appear to have a Miter of propertlea la First, the equlllbrlut betveen the acre Mobile lover-valency fore*, and lea* Mobil# higher*valency forma depend# c oxidation-redacttoe condition*, pH, and occasionally 00 Microbial activity. Theee factor* May all be Interrelated. Recced, to aone axteot they occur a* chelatee, either by accueulatirg biologically In living ayateaM, or by resetlag vlth noil organic natter. Thla generally dacreaeee their availability, though not neceeearlly their nobility. Third, j s i: -17to different degree* the heavy Metals are ccnpstltlve vltb iron. The fe&erel order of decreasing competition teens to bs Cu>CoHl>Cr> Zn>Kn>fb (35. 51, 72, 155). The order here gives Is sppreaciMSte, and the transposition of soy tvo adjoining Metals should he bald possible. The toxicity of these Metals to pleats does not necessarily follov the * saae order, fourth, the phosphates of the heavy Metals ere rather insoluble, especially under alkaliL* conditions. j It thus follows that unfavorable effects of heavy nstals on plants csa generally be alleviated by one or nore of the following operations: A. Increasing tbs soil pH to above 6, such es by liming. B. Orgaalcaatter treatment of soil (stubble Mulching, green Manuring), the pH i being sear or above 6. C. Application of fe, particularly as the IOTA- chelate, either follarly or to the soil. D. Application of phoaphatee, provided the toll pH Is Managed properly. Absolute values for the different treatments depend entirely upon species of plants Involvsd sod ecological conditions In topo. Jl '5