|
<br />EVt,J.llt.TIII'; Ill" I.CfJ!.fl\:tCAI. l:HFTI~ il~ !;lI.VI.I: IllilflJE SEEDING AGENT).!
<br />POllllld \. r]plll?.' .111.1 1'];'11,11.1 S..hll
<br />
<br />ABSTRACT
<br />
<br />The possible effects of sUver iodide Sf'f"d 1 liP, af.!ellt
<br />accum.ulation in surface soils of the SiW Juan arelt
<br />were investigated by use of lAboratory !Hudlefl In-
<br />volv1ns Arthrobacter - silver internct Ions, trentmt>lll
<br />of .01111 with varied formn And I~V(>JR tlf 1'I11v(>r. hy
<br />eX8mination of silver Rr8dlent~ surrolllldlllg 6(!edillp,
<br />generator sites, and by use of trClltm~lll pIotR III
<br />Rpruce, aspen, and JIIubalplne mefldow cuml1llllllt 11:'."
<br />located ill the San Juan snow uugmcntllot lUll IHN" I,nb"
<br />oratory studies have shown that on 8 shoTt-term basis,
<br />silver iodide or seeding generator burn mixtures nt
<br />higher than field concentration show onlY slJght
<br />effects on microbial Rrowth or enzyme function, while
<br />free silver ions. even at part-per-billlon levels.
<br />can cause marked' changes in microbial activities.
<br />These etfecu were 1"~8ened in the presence of soil or
<br />complexing 10na. However. under field conditions on
<br />a 3 year basis. .1Iver iodide appears to have a great-
<br />er potential for alterinR soil decomposer functions
<br />than silver from .ilver ion. The presence of silver
<br />from silver iodide - sodium iodide complexeR. BRAin lit
<br />hlfl.her than bac~sround levelR. In the' !inn .1111111 tf1r~p.1
<br />IIreR I(>d ro" graduaJ IlIl'rl'IIRt:' III null 01"1(111111' mllltl'"l
<br />content III spruce and aspen 8'Il"fflt"t' sulIs. Nil !411l'h
<br />lncr-ellse WIUiI ob..rved In the f1uhn] piliP Inl'lhll1\J plot,
<br />Silver from silver nitrAte telld~d tll CO'll:~lltrllt(' mllrr
<br />in upper plant portionll thAn ullver from sllvpr 111111111"'.
<br />although silver from silver iodide waa more C losl'lly
<br />usociated with the plant roots. These effects, were
<br />only observed using sUver levels IO-lOOX expected
<br />field Accumulation levels. BlIsed on the available
<br />Uterature and experiments carried out to date, the
<br />accumulation of silver iodide seedJIlR agent tllleA 1I0t
<br />Appear to present an ecological thre/lt, altluHIRh cun-
<br />tinual monitor ins of test systems should he I:llrrlecl
<br />out to extend t:he time period over which thlll ('011<"1,,-
<br />slon can be tested.
<br />
<br />OBJECTIVES ANT> HYPOTHESES
<br />
<br />1.
<br />
<br />To monitor soil microbial activities In the Sail
<br />Juan area, to determine if possible sIJlv~r~~~c~e-
<br />tion is influencing soIl microbial,processes.
<br />ro analvzG traatment plot 80!I. to ~~lc~~~~!OUR
<br />sUver addItons have been maae-rn-ispen. spruce,
<br />;nd grass communities. ---".,-"
<br />To measure mlcToblal responses [0 silver jo;\'AdieOlf;
<br />p~-~sent In the vicinity of the Pagos.. SprIngs sell;';'
<br />era tor site No. 25, and the Emerald t1ounFnl""il:li:e.
<br />To-determine the existence ot possiDli"fiiiS=1eflilil
<br />e1 fects at variea SlIver l.e\'e1.8 ana Iorms -on----
<br />microbial processes, intluding ertetts on mICfotir=
<br />al viability and capabilities to transtorm 9ij6~ "
<br />.strates requiting enzymatlc adaptatIon a~~"~~~(~~-,
<br />production processes.
<br />To determine if soil microbes are capable of
<br />transforming silver present as silver iodide'to
<br />additional .Uver forms. and to determine phyilo-:"
<br />logical mechDnisms which may reBu1l In ~~l~~
<br />transformations.
<br />To determine if a"ssoy prot.:edul"cs ro~"_~!..~I_~v_~~
<br />(orms 1n 8011 ('Rn be Jev~lope~_._"
<br />
<br />2.
<br />
<br />1.
<br />
<br />4,
<br />
<br />s.
<br />
<br />h.
<br />
<br />These ubjectives hav~
<br />hypotheses:
<br />""HYPllliletlii9 I.
<br />
<br />been Stllnm.ur I z ed
<br />
<br />in ,1 !l,~rie. of
<br />
<br />Accumulation or NJlver iodide rr...
<br />weather modlftca[ion will re.ult in no
<br />overt toxicity effect., bot may r~~\llt
<br />in a slight delay In bloloS1c.l
<br />
<br />Hypothesis 11. I.nborstory studies Cal\ give all 111(11(:;1-
<br />tion of the degree of possible dlmin-
<br />tllltton of microbial activity which
<br />might result (rom sl1ver accumulation.
<br />: Ilvpnth"fl!R III. Soil btlcterlA CAn caU8e H change ill
<br />~ilver iodide to form8 more ensily
<br />111kp.1l lip by plAnt~. ,'blR mntlifjrl1tlnll
<br />of l'itlver farm milY mn\<e iL lICCC!5~j,1ry
<br />tu carry out experiments tinder field-
<br />relnted conditions All much 118 p08Rthlfl.
<br />
<br />""""A"' -II" ~'Y'''S ~~C '/-,onS 0,..; rreJ.-'
<br />
<br />1l;ISl!J (Ill work carried out on the possible ecoJop.ic.1l
<br />effects of silver iodide seeding agent accumulation in
<br />soils of the San Juan area, the following conclusions
<br />'":111 IH' dralJt\:
<br />
<br />I, ]'!,=_sccutJIulation of silver iodide nuclea~J..f.!..~al!!l!~
<br />prf'Sf'nts tlO overt danger to humans. plants or ani-_
<br />mals, hascd on available literature and work ~a~: "
<br />~!~_~~.':.._~!!!t1l'l' Llds study for a 3 Year oeriod~~."
<br />" ~iJ lVl'r 1"'1 ('nil t'(lllf:P decreased ~ro\.l'th /llId enzymE'
<br />fiiJlicf"TOii- ~~"~~ 1ll:?J! Arthrobact:cr _~p'ec~_~~ ~t" i-IO
<br />pph free ~liv~r ion. The effect. observed (~ del'N\-
<br />d('lIt "" ;tlill:j:" :.;1 i;'IIA Rnd CRt Ions prest'nt. So 11
<br />dccn'AflpfI thp /let jvJty of free Ililver Ions.
<br />l. SJlvl'r (rum I'lllvE'r iodide or hurn mixtures dop.tiI
<br />uil1 iiftnloiA"iiai-TIrr'ctH on fIllcrot'lanrnilUfcrr lh:':'
<br />7.yml-lilr.-iirrfV'rty:--r.enerolly 10-100 _epm" af'Ag!
<br />foFiil"iiflvcr-lir'req"iiired to oEi~-eHect$ on
<br />growEfi. -vJn6lTIty, and enzyme Induction;-'-
<br />I." F'i~P.RfT\i"rIOll from Bllver iodide dIesocial Ion at
<br />')-fl pph ('1111 ,';'1116(' l,bservable effects on mfcnl_
<br />orRAllt8ms. To Rchieve this slIver level
<br />100-200 "pm or silver A8 sUver iodide i1re re-
<br />(Iulr('d.
<br />S. Micruoq~Bll16m9 call cause reduction of free stiver
<br />Ion or Allver fodJde to metallic silver. Amine-
<br />type mAterJalA moy be respansible for this reduc-
<br />tion.
<br />6, Silver iodide added at 1000 ppm shows no immediate
<br />~ffects on 80il resoiratlon processes.
<br />1. Attempts to estsblish respiration indices tor test
<br />Aoils acr08S the impact area vere not successful
<br />due to short-term variability of soilqttoJature and
<br />tempf!r4ture.
<br />fL Silver accumulation in the vicinity of two seeding
<br />generator sites did not cause decreases in m1cro=
<br />blal respirAtion. Silver tended to sccumulnte"and
<br />remain in the aureate 8011 zone In eplte o(""iH(~
<br />tin~w4ter percolatIon throuRh tha tone.
<br />9. ^ ~ sub81pine lIleadow teatp!Oi-fii8t'aUed -tor .1 years
<br />using sliVer iodide and stIver nttr.te at 1. 10.--
<br />100 ppm surface soil levels did not show changes
<br />~ecomposer functions which could be rel~.te4."-_fo"
<br />this treatment.
<br />10. STIVir-rr0m-811ver iodide moved to upper plant por-
<br />t Ions to a hsser extent than silver from silver
<br />nitrate.
<br />11. Siiver from silver iodide vas more closely a9socl-
<br />."lted wJtll plant roots than silver from silver Ion.
<br />12. Artel' 1 years, sHYer from these two differing
<br />orlglnHl forms have not equilibrated to forms
<br />which w11l gfy~ similar activities.
<br />11. In spruce and a.pen plots, imposition with silver
<br />Iodide tends to be related to Increased organic
<br />m.tt.r r.t.ntlon In the test 8yatems. No such
<br />r.tation.hips were observed with equivalent treat-
<br />ment. uaing silver from sIlver nitrate (slIver
<br />Ion).
<br />
<br />J) tn Steinhoif, n.~"., and J.D. hes (Ed.). 1916. F.colo~ical Impact.s of sno\lpack
<br />Mountains, Colorado. San Juan Ecolop.y Project, Final Report. Colorado Stllte
<br />J/ Present address; Dept. of Hicroblolop.y, Colnudo State Unlv.. ~t. CoJlins, Co.
<br />
<br />augm.entation
<br />Univ. Publ.,
<br />80523. '
<br />
<br />l.n the San JUAn
<br />Fort ColUns.
<br />
<br />12'
<br />29
<br />
<br />A-Bd-2
<br />
|