DISTRIBUTION OF SILICATE IN THE SEA 



as 



Table C3. Mean silicate content at standard depths 

 in the Pacific (mg Si02 per liter) 



the case of the other nutrients. This is ^toxni grst^i- 

 cally in figure C2S where the vertic-sl di^ritoutioa cf 

 silicate and phosphate at station 1ST is preseated. Tt»e 

 continuous increase in silicate to great depths \T*d\cstes 

 that the silica of the diatom tt-ustules does not dissoilrx? 

 as rapidly as the organic matter of the planktcm decom- 

 poses. There is also the possibility, hovrerer. that or- 

 ganisms having siliceous skeletons sink more rapklly 

 than do others and thus reach greater depths t>^c>rett>eT 

 are completely dissolved. There are other bioloj^ical 

 factors which prolwbly contribute to the difference In 

 the vertical distribution between phosphate anvi silicate. 

 Most of the plankton animals maintain themselves aboio^ 

 500 meters whore their excretory products may con- 

 tribute material quantities of phosvM\ate K> the i»-ater b\»t 

 probably do not add any appreciable quantities of sili- 

 cate. This may viartly account for the more rapid in- 

 crease in phosphate than in silicate in the uv>per 5lH1 me- 

 ters. Furthermore, the radiolarians are \nvvlv\M in the 

 silica cycle since most of them have siUc«vus tests. 

 They are found not only i<\ the photosynthetic <ione. but 

 at knvev levels. Silica vemovtHi fronv (he water V<y 

 these oi>vanisn>s would lower th<> stUcato concentration. 

 Ulliniately thi.s .siltcalo would be dissolV(Hl, but prol>a 

 bly at a lower 1<>V<>1. c\M\.>iequently the r;uliolarian,v <n;«>f 

 be partly re.'ipon.sible lor the silicate m;i\tuvui\v occur viivg' 

 at lower levols thsm in the case of the other nutrients 



REGIONAI. DiaTHUUITUlN 



Fi^uro C19 whowH thf rnfiiii vcrtlc;)! (Iliilrlbutloii nf 

 silicate at two (;roupH of f,';irni'(/l<' ntiillonM. Curv(> A 

 showH th(! moan dintrlbuDon ;it ;il;illon;i li(!lw(!<'M IjiIIIihIcm 

 20" and 34' north (Htationn 133 to MI)) wli<wo;m curvi' 1.1 

 reprcnf;ntfi th<; m(;;»t) dlfitrlbulloii ;il ril;ill()tw( bi'lwc'nii hil 

 itud<;H 20" north ;in(J H" nouth (fi(;i(loiin 11)0 (o \(\V.). 

 Thf.'fK; curv'.'K nhow tliiit (hf coiici'ninit Ion of nllli;ili' In 

 thr; upper 300 fru'l'TTl ;iv<t;i(/i'(| cnfK'fil liilly tlii' riiiiin' :il 

 the two y_r'>{ijn', of nl:il)onri. AiioIIiit nlmlbirlly In (Iml 

 both f:urv>'f! jihow rri;i;(lm;i ;i( ;ihoiil !l()f)0 mi'loiri, Tlii'in 

 arc fitrlklnw i\ittiTi-urf!',, Iiowi'Vit , hflwiwi dn' (wo 

 Rroupf! of (il;it)orifi, At Hi'- fioiillKoii fi(;illonn lln' Iimm'(1IIH« 

 In nlllc.;ilr: wlltj 'liptli w;iFi rriiicli iri'tii' (/i;iilci!il bolow MOO 

 mctirr/) ;in(l lti<- ')i);>rillllcfi wi'/o lowio limn ii( llii' inoi'i> 

 northern i'A:ii)(in!t. Al l')0') ;in'l 'I'lOO irn'lioM lln' ininin 

 viilijcfi for ttie two (/roupf, of fihilloiin worn, i I'fiptii't Ivoly, 

 0430 ;in<J liZliO rnj/ i',\<>-/, (co riibic KieUo' for tlio ttiiri|i»i' 

 aid 7,orn;, but only ^iVIJO ;iii'l W/A) rrij/ I)I»>Z l»"r cubic iiin 

 tcr for lh<! troplcw. At ;ill oHiei IuvhIm linlow nhoiit 70(1 

 m<;l<;rri there v/:if, sipproxltriiitely llie «siiii<' illtfei <incci lie 

 twef.'M the nllieiile eorif<'ii( ;il lh<' two {{roiipn of Mliillonw 



It hi <ilffl<:iilt to ;»r)«li/»i ■> / "(imoii for lliln illffionncn 

 In the cori(;entr;il)of) of mHI'JiI" In lli" mI( iilowpliio n IiiIIk' 

 two re(/lon(! of the I'Jielfle, AIII/oW|/,li llmMi 1« pliicllciil 

 ly nt) j)'((;!;)bllily lli;)l tin- f,t'Uiiii iiH^ on llii< IioIIoih of Ilii' 

 oc:e;ifj coul'l ;)f/e<;t fli«' i:li''in)>:;ii i oiopoMllloii of llm wiil'O 

 ;it (/re;it 'll/daneeM fforn tip" bollofii, m v"( (ln'I'iMM II Im 

 lnt«:ref(tln(/ to note lli;it (In botloin Bd/iipliia olihtliixi) by 

 th<.' C'rU'ietjle ;i( the rIjiIIodm )ii Hk' mi(/1oi( wIco h IIim mII 

 l'::il<- e()rite-iil w.if, (()(/h eoiittlwl of r«() cjiiy, wliiwciitH 

 Uio,-!i- ol)l;i)in-') ill ()(;il|/);)e! whu/ a «))|(;kIu coiiIwm) WIIM low 

 (/eiJ'Tiilly (,oi/l;.l)i< 'I ;i |,)(j)) ptti't'jttnitttiO ttt mMmtt I'MI' 

 bon;ili- 



AIHiOi)(/h i-,lil»;it«« WMM fUli d«rt«»»'»lbl<«<l III «o (Kiiiiy 



localltliTi ii;i Wii;i Ihc |)lioripli:itc, m-vcv tUclcun the \cm>U.<» 

 Dbliilnoil ai'c rmtfli'lont to lu(llc:ili< Hint the dlf»t\'ll«tllon of 

 ;iUU-:il<< Im ilclcrnilni'il by llif Mitnic bloloHb'itl and hyiivo- 

 |j.r:i|ihli' I'onillt liiiui Unit dcliMiiiIno the illnlrlbnilou \\{ 

 pliciiiphiili'. 'riil;i liidlciitini ll\;il lhi> it>(ilonitl dIntrlbuUOU 

 lit liiilli Id diilcruilni'd by cnnenHiiUy the mtm«i phynU'lO 

 :iiiil liliilop.lral filcliirn. 



Al ;((Mi(i iiicii-rM Ihd mwtn pluiBphttIt* Vttlvie fitr the 



iiiirllii'in K'onp ol fidillnnn, belwiuni liitlliiilen "JiV iindA4" 

 mil III, wiiri ^1711 iiiK I'O-I pr'i' I'liblc niotoi , lor nliillonn 

 Mil III III'.',, rtiiiilli lit .10' IIIM III. It wiin 'JI'J<I lilt) VO\ pi)r 

 ciililr iiicli'i Al lliln ili'iilli Hie pliiinpllillc ciiilli'lil ill lh(> 

 riiiiilliio II p,riMi|i nf Mliillniin, lliei nlorii, wilF* 17 pot' oeill 

 liiwi'i lliiiii till llici iiiiiin mil llicrii Hi'iiiip, wlioreiin In (liii 

 iiipte of (lie f4llliH(lti Hill ilirtiii'<Mii'i< wiiB Hn pt>r cent 



II IM nf liileirml In ciinijiiire llii< ikmiiIIm nblllllli'il by 

 Hie Cui'llt'lile Willi lliiiFie Inilll I'liiinllll ill Oiin nt llli> I'lli'll 

 Ic. rliicli M I'liiiipnrlfiiiii Im lOveii In ll|tiiii< I'lM, where 

 nil vcM tire nlliiwii till Mniileiev Miiy, Hie In |iillil ie|tli>il, 

 mill Hie iiveni|fe tin niNleeii t.'ill llt'Ub' f^lillliiim mil III nt 

 'M\" iiiirlli, III Miilileiey lliiy, hl|teliiw iiuil IiKnIIh |HKIII\ 

 tiMiiiil Hie iivei'iiije eniieeiili iillnii nt nllliHlle bir miveiill 

 Mliillinm In be nillM* iii|( hlllu per eiilile iiinliil ill ItltiMlir 

 ttice, The i|HMtillly liiei eiineil riijililly In till iiinliM'n 

 wlieru Hie iiieiiM WIIM '.tllllO tli|t flhlll pel eilllle lll|i|)ir, I4tl 

 low lliln Hie liiereiiMe beeilllie iiliii e ||lililll)ll mill III (111(1 

 iiimIhim Hie eoiiretil rill Inn nf Mllleiile iviiM '1*11111 IIIM FilllU 

 (lei I'lililr Dielei The I wn piipei m by Mnliei n pievlnilMlV 

 elleil |ii iiMeiil nllleiile iilmei villlniifi III iiliillniiM nil Hie 

 ■ oiimI of I'lilltnrillH Iimi lUipHi III Hill iiinl urn, 



** Till' Viilili'M I eiiiii led by lll|fe|iiw iIIhI I.eelbi llllVH 

 mm IMHlllplleil by I :| in iiMilie Hieii( Mptllllble wlHill 



iHiHi'N, Nm« ItluMlow Hint liUHib' (ll)!tli, |i m), 



