Biogeochemistry of bog iron in the New Jersey Pine Barrens

Chemical Geology, 24 (1979) l 1 l - 135

11 I

i,.> Elsevier Scientifm Publishing Company, Amsterdam - Printed in The Netherlands

BIOGEOCHEMISTRY OF BOG IRON IN THE NEW JERSEY PINE BARRENS

D.A C R E R A R , G W

KNOX

andJ L M E A N S

Department oi"Geolog=cal and Geophyslcal Sciences, Princeton Unwcrszly, Princeton, NJ ~J~5.10 (U S 4 ) (Recewed September 6, 1977, revised and accepted December 30, 1977)

A B S T R,A C T

Crerar, D.A., Knox, G.W. and Means, J.l.., 19'79. Biogeochemistry of bog iron in the New Jersey Pine Barrens Chem. Geol., 24: | 1 1 - 1 3 5 . Rtvers and swamps of the southern New Jersey Coastal Plain contain sporadic bul. quant,tatively ,mportant deposits o1" bog iron. This consists of unconsohdated to mass,re limontte impregnating sands and sdt,s, [,he only X ray =dentifiable Fe mineral being goe t.h=te The chemistry and hydrology of' river, swamp and ground waters suggest that Fe ts

supplied by lateral and verttca] migration o1" corrosive, actdic LO'ound waters up through lee rich sed=ments toward aerated surfaces Here oxidation o f Fe is catalyzed by Fe fix ing bacteria including Thiobactllus ferrooxldans, Leptothr~ ochracea, CrenothrLr poly spora, Slderocapsa gemmata, and Metallo&enmm sp. These bacteria are essential to the

precipitation oi" Fe, which would not otherwise oxidize at significanl, rates given the acid pH and chemical composition oi' surface waters.

I_NTRODLICTION

From the early 1700's t,o the mid 1850's southern New Jersey was the site of a flourishing iron industry (Bayley, 1910; Braddock.Rogers, 1930; Pierc.e, 1957; SLarkey, 1962). Local thin deposits of bog iron provided raw material for a great, many furnaces and forges in the area. Oyster and clam shells were the most c o m m o n l y used flu.x, and c.harcoal served as both reductng agent and fuel. The industry, which boomed for almost, a century., producecl cast iron pipe, stoves, tools, cooking utenstls, and other items for the east coast cities. In addition, it served as a principal munitions supplier for the Revolutionary War and the War of 1812. The discovery of anthracite near the magnetite ores of Pennsylvania and northern New Jersey eventually doomed the bog-iron industry. In addition, the bog ores contabled high concentrations of P and S, making them unfit, for the production of steel. As a result the South Jersey industry declined rapidly afl,er 1840. Within 25 years most, of the region had returned to the wild st,aLe and it, remains largely unpopu.lated t,o thts day.

112

Probably because such dPposit,s are no longer e v o n o m i v , t,here have lJPPn l'Pw m o d e m st,udles oI' t,rue bog ir~m occurrenq'e,g eil, her in New Jersey or ~Ise where, r['his paper describes t,he st, rPa.rn- and 1.9"ound wal,er vhemtst, ry of t,h~ Sout, h ,Jersey locaJ,l,y mid focuses on t,he mtcrobiol,a w h i c h appear t.o cat,a lyze bog iron deposit,ion (~,EODO(.]Y

New Jersey may lle ,,~ubdJvlded int,iJ three main geologic pray]noes as illus t,ral,ed in Fig. I a.rt,er (')Isson (1963). In t,he cent,r'aJ Piedmont, Province t,he

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113

dark and red shales of (,he Triassic Newark Group noneonformably overlie Precambrnan and PaJeozoic basement. Late Cretaceous-Eocene sednments outcrop in a narrow belt, bordenng t,he Piedmont. This belt, and the more southerly Miocene--Pliocene (?) sediment, s const, itute the New Jersey Coastal PlaJn - essentially the nort, hemmost exposure or the Atlant, ne C(.)astai Plain (barrnng small out, crops on Long Island and Nantucket). Topographically, the Coastal Plain =s flat, and Iow-lynng, with poor dramage, many swamps, and slow-Ilowing streams. The two major rivers, (,he Mullica and the Great, Egg Harbor River rail only 1.5 m in 25.7 kin, and 1.5 m m 37 kin, respectively. While bog iron is widely distribut,ed throughout the en t,Lre New Jersey Coast,al Plain, nt is most (.'oncentrat,ed m (,he lat,ter t,wo drainage basins (Starkey, ]962). The stratigraphy or the New Jersey C()astal PlaJn has been detaJJed else where ((.')wens and Minard, 1960; Olsson, 1963; Richards, 1967; Minard eL al., 1969, 1974; Anclerson and Appel, 1969; (:)wens and Sohl, 1969; R,hodehamel, 1973), and us only brielly outhned here. Dippnng seaward at, usually less t,h=~ 9.5 m per kilometer, t,he sediments are roughly 300 m thn(.'k in outcrop (Olsson, 1963), and thicken to roughly 1.2 km both seaward and t,o the s{,)uth. Fig. 2, from ()wens and Sohl (1969) us a schen~atnc cross-sect, non B

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,: ,.' ',',',',, ', :', ',, : ,,'.','.,' ,,, ',. '.'A'~'E'ME. ~",', ,',' ",',' ',',' ",' ,',',', 'i ',"' :',".',",' ", Pig 2 Generalized (-ross section from A to B on Pig. I showing Lhe appruxlmate thick hess and lateral relations of the Coastal Plain rorrnations Pred(Jmnnantly glaueunitlc units are ~tippled

114

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approx,mately along strike, and Pig. 3, from Anderson and Appel (1969) dlustrates the downdlp seaward thickening o1" st,rata and the underlying succession of aqui rers and aqLut,a..rds. The sediments, which are unconsolidated or partly consolidated, consist or interleaved marine, marginal manne and nonma.nne formations. Sediment, types vary. from the beach sands and ailu,,nal gravels and clays of the overly.ng Cohansey and Kirkwood Formations to the highly glauconitic Hornerstown, Merchantville, Marshailtown and Navesink F'ormations. Carbonaceous and giauconitic silty clays are interbedded in the Magothy, Merchant.ville and Woodbury Pormat, lons. The entire region is overlaJd by a discontinuous veneer ol" Quaternary. sand, g-ravel and clay - the Bridgeton, Pen,,.,auken and Cape May Formations in order of decreasing age. ()wens and Sohl (1969) have concluded that, the Coastal Plai.n section rep resents a cyclical pattern of marginal marine t,rans~esston and regression with out,ershelf greensands .n any cycle being overlaid by near-shore sdty Lmits, and finally by beach sands and gravels. Pe occurs throughout t,he section predominantly as glauconite in the greensands and glauconitic clays noted on Pig. 2. It is also locally abundant, m silts and clays as siderite concretions. Pyrite and Vlvianite have also been described in interbedded glauconit, lc marls and shales (Braddock. Rogers, 1930; St,arkey, 1962). Finally, the uppermost, Cohansey and Ku'kwood Por matlons are heavily stained and ol't,et) pa.rt,ially cemented with Fe oxJdes. HY DROLO(3Y Today, water has replaced Fe as the principal resource or the New Jersey Coastal Piton. The northwest limit or outcrop o1' the Cohansey and Kirkwood Format=ons defines a relat, ively undeveloped area of some 5830 km 2 lulown h.)cally as the New Jersey Pine Barrens. Desp=te its proximity to the major east coast, cities, this area remains almost totally undeveloped and tt,s waters axe pristine and unpolluted. In 1 9 5 4 - 1 9 5 5 , the 384-km ~ Wharton Tract was set aside by the State of New Jersey as a ground-water reserve to meet, future water requLrements in the Camden and Atlantic City areas. This tract, which is centered about the Mullica River drainage basin, was chosen as the stt e of the present study. As tllustrated in Ftg. 3, the New Jersey C,oastal Plain is underlain by a suecesston of aquifers and aquitards, the latter becoming increasingly glaucon itlc and clayey dow-ndtp. The principal aquifers or the Pine Barrens regmn are the Magothy, Rant, an, Ktrkwood and Cohansey Formations. Rhodeha.mel (19'70) has estimated the usable water reserves of the Cohansey Sand alone u} this region at. 40.9.10'" I. The uppermost, aquifers, at, least, are hydraull tally interconnected. To the south and east, an increase m the silt, and clay eont,ent of the C,ohansey Sand and upper KIrkwood forces ground water to the surface (Rhodehamel, 1970). The streams in this region are fed largely by ground water baseflow. R ho dehamel (19'70) developed a hydrologic budget, for the Pine Barrens based on the relationship:

1 I(;

P=R+ET where P = average annual precipltal, ion, as mlllinlet,ers depth over t,he area (114 0 mm ); R = average annual stream runoff, measured as milhmet,ers depth over the area (5"/(.) ram) ; and ET = the average annual evapot, ransph'ation, as millimeters over the area (570 mm). 'The model presumes no ground-wat,er basel'low t,o the ocean due Lo the seaward decrease in aquifer permeability noted above. Because P and R are determined from rain and streaJ'n-gauging sLat,ions, and ET is comput,ed, then any ground.water discharge to the ocean

would simply decrease ET. Most imporl,ant, ly for the present, purposes, R,hodeharnel also estimated that, ground.water basellow supplies roughly 89% oi, 'all river water, the remainder coming l,rom direct, surface rUlml,l`. Hence, rivers tn this region are almost entirely fed by underlying aquifers, many or which cord,am high content, rat, ions of Pc. The Cohansey Sand, which ts the uppermost aqml,er, ts relatively unreac t,lve chemically, consisting pnmarLly of quartz sands and gravels with Im"a.I clay lenses. Studies by Kelsey (1971) and Gay ( 1 9 7 5 ) o n the prectpit, ation and rwer-wat,er chemistry of the Cedar Creek drmnage basin in the Pine Barrens are summanzed in Table I (Gay, 1975, p. 65) This table ts based on unpub TABLE I A n n u a l i,mlC load budRel, for (."edat ("r~Pk Bm, lrl m met.rie I.~Jns km (I,q'75) hmlc

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hshed data by D.J.J. Kinsman aJld R. Yuret, ich (1972), and shows that preclpit.at, ion input, of major ionic species approxlmat,ely equals river out, put,. In ~l, her words, Na', Mg = ', H' and C I are essentially rlushed unalt,ered through t,he ground-water syst,em, while somewhat, more K', Ca ~ ' and SO~ enter the basin each year than art removed by rivers, t,hese being prestu'nably retained by vegetal, ion (Gay, 1975). On t,he ol, her hand, SIO,, analyses m Cedar Creek ranged from 10.2 t,o 0.77 ppm and Fe I'rom 0.1 t,o 0.4 ppm (Kelsey, 1971) while ct)ncent,rations of both elements in rain wat,er were at, or below t,he approxlmat,e (.).1 ppm Iimll, of det, eet,lon. Hence, significant, quantities of bot,h Pe and sllwa are being introduced t,o the dranmge system by underly ing aquil'ers.

117

FIELD A N D L A B O R A T O R Y

INVESTIGATIONS

While reconnmssance surveys were made on all major streams in the Pine Barrens area over a three-year period, we focused our attention primarily on the region around Batsto, shown on Fig. 1. This town on the Mullica River was a center of bog.iron activity for neatly a century. Streambeds in t,he area ate coated with freshly precipitated Fe oxides, and massive deposits, which are scattered in distribution, occur under river banks, and in adjoining bogs. The ochre to red precipitate is virtually ubiquitous, coating plants, pebbles and streambed detritus, and collecting as flocctdent masses in more stagnant waters. All forms of ore were originally exploited, these being defined according to texture as "loam ore" (loose pre.cip=tate plus soil or sand), "seed ore" (partly consolidated) or rock-like "massive ore" (BraddockRogers, 1930). Once mined, it, has been said that the ore took somewhat, more than twenty years to regenerate (Statkey, 1962), although this growth rate has not been accurately measured. In fact,, the bog-iron industry began importing additional ore by 1840 (Pierce, 1957), and surprisingly little bog iron remains in the Pine Barrens today suggesting much slower growt, h. Typically, the bog iron is soft and earthy, containing admixed sand or clay. Oolitic or concret=onary, structures are rare or absent. Fig. 4 shows the typical texture of massive bog iron, w.th rounded, well sorted quartz grains thickly cemented by limonite. The ore composition itself was that of an Lm pure limonite, old assays ranging 12-60%, but rarely e~ceeding 30% Fe (Bayley, 1910). The bog iron shown in this figure contained an average or 27.3 wt.% Pc, 34.7 ppm Mn, 129 ppm Zn and 92.9 ppm Cu. The only Fe mineral identifiable by X-ray diffraction was goethite, the bulk of the ore consisting of amorphous Fe oa ides and/or hydroxides. Between June 1976 and July 1977 the Batsto site wa.~sampled on approxi mat,ely a bimonthly basis. Surface- and ground-water samples were collect, ed [TOm the Mullica River area and analyzed for chemical and bacterial con tent using the methods outlined below. Massive bog.iron samples were taken from deposits =n ephemeral streams and bogs wit, hin the same area. Methods Stream and ground.water samples for chemical analysis were collected =n acid-washed polyethylene bottles, pH was determined in the field using a high-sensitivity combination electrode and an Orion ~ specific ion meter, model 407A. Eh was also field-determined, using a Pt electrode with a saturated A g - A g C I reference and an Orion ~ pH/mV meter, model 601. True Eh was derived from the conversion factors of Langrnuir (1971). Eh measurements were repeated until stable and reproducible results were obt,amed, t,hm seldom requiring more than 10--15 rain. Because the sampled waters are acidic, oxygenated and relatively concentrated in Fe, their redox-buffering capac=ty should be high (Langrnuir, 1971 ), and accordingly the Eh readings were fast, and stable.

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119

For those samples which were filtered, doubly acid-washed What, man I~0 moderate retention papers and/or Millipore c# or Nucleopore c~' membrane filters were employed. Immediately aYt,er filtration, samples were acidified to pH 1 or less with trltrex ~'-~concentrated HNO3. In the laboratory total dLssolved solids (TDS) were determined by evaporating a known volume of membrane-filtered sample to dryness at 110"C. Dissolved organic C was obtabled by analyzing the TDS residue on a Leco ~c~c a r b o n - s u l f u r analyzer. Fe and other trace met,aLq were determined on a Perkin-Elmer @ model 603 atomic-absorption spectrophotometer graphite furnace. Experimental procedures for ion-exchange and gel-filtration chromatography (G FC) analyses aye more fully described by Means et el. (1977). Samples to be analyzed for bacteria were collected ~'om the a i r - w a t e r in terrace, from subsurface bog waters, and Erom flocculent gels coat,ng submerged plants or floating on the surface. These samples were collected in autoclaved 500-ml Nalgene c~ bottles. WATER CHEMISTRY

The pH, Eh, TDS, dissolved organic C (DOC) and various trace-nwtal contents of selected Pine Barrens' stream and ground waters are given in Table II. Stream-water analyses have been taken from approsimately ,50 samples collected from June 1976 through August 1977. The ground water analyses represent some twenty samples collected during May and June 1977. Stream water

As indicated in Table II, stream-water analyses have been obtained for Ceday Creek which flows from Bamber to Lanoka Harbor, and the MuJlica R.iver, between Atsion and Bat,st,o, New Jersey (see Fig. 1). While both streams occur predominantly in the Cohansey Formation, the MuJlica has a much larger drainage basin than the Cedar, and many of the major bog-iron deposits occur in the vicinity of the Mullica. Accordingly, MLfllica waters contain higher levels o1' Fe and other trace elements than do Cedar waters. The trace metal values o£ Toth and Oft (1972) and Fe values of Coonley et at. ( 1971 ) aye m good agreement with the numbers in Table II. Other stream-water compositional data, such as alkalis, alkaline earths and inorganic anions may be found in USGS water quality reports (e.g., Anonymous, 1976). Seasonal fluctuations in the pH, TDS, DOC, Fe and Eh of these waters have been observed. Organic C, Fe and TDS are higher during the summer months than in the winter while Eh is lower. Seasonal variation in Eh is slight compared to pH. Summer pH is generally higher than in fall and spring, atFig 4 A. Thin section of bog iron showing quartz and limonite matriz B Scanning electron micrograph or bog iron surface showing hrnonite¢emented quarl, z grains.

12()

TABLE II Chemical composltloru~ or seh*cted st.re~Lm and grf)und waters from the New Jersey Pine Barrens

m

Cedar Creek

Mull!ca River

D~ep ~'ound water

Sh.-*llowground water

pH Eh (rnV) 'T'DS* ] (ppm) DOCk' (ppm)

,4 l - h 3 bOO--700 Ib-2b !-!0

4 h-b7 375-62r~ .,, _r.~0 ,)l1-1()

4 7-4 8(ave.) 4 5U(ave. ) 30(ave.) 1/2-!

Fe, total(pph)

LlO0--1000

, 50()0

50()-lbUi)

,4 ;3-4 4(ave ) ,r')(lU(ave.) 40(ave ) l/2-b 50-3()U(} { IO0(uve )

Fe *~ dissolved (ppb)

25-250

bO(P-IO()U

!-~00--1500

h(~--3000 { IOt)(ave )

AI*,, (ppb) Zn (.ppb ) Cu (ppb)

50-1000 5-T.~

50--1000 2(.)--70

300-600 b-25

1-30

1-30

1/2-3

_

l!,-2b

!~- 1b

2~)0-4500 1-71) 1/2-:]

b-22() { 20--3(.}(ave )

Mn (ppb)

I~- I(I

Pb (ppb) Cd (ppb)

1-5

I - It)

I-2

I/2-3

()-[

()--I

0-|

0-2

ave = average value '*Collected from wells sereened at depths rang,ng 35 l - 7 f i 2 m ~Collecl.ed from wells screened at depl, hs langing 3 O- 17 2 m, mostly m the 6 I - 7 . 6 m range J*Tutal dissulved sulids obta,ned on 0 22 pm membrane I',ltered samples ' * D,ssolved urganK" (3, mostly humw and fulwc acids • ~ Defined as 0 22/Jrn Iill,ered. ~b All trace rnet,al values other than Fe rel'er t,u unfilteled samples

though e x c e p t i o n a l l y low gummer values have been measured at, some slt,es. Winter pH varies, w i t h relatively high values observed d u n n g the w i n t e r o f 1 9 7 6 - 1 9 7 7 and l o w e r values d u r i n g the w i n t e r o f 1 9 7 7 - 1 9 7 8 . The rise in D O C d u r i n g the s u m m e r m o n t h s is attribul`able t,o the increased rrucrobial degradation o f vegetative debris. T h is increased organ it-acid inpu I, is, in turn, the likely cause for the l o w e r s u m m e r pH measured at, specific sites, usually near bogs. The higher s u m m e r pH values o b t ~ n e d at, most mid st,ream sil, es p r o b a b l y represents c o n t a m i n a t i o n from nearby agricultural activ~t,y including liming and ferl`ilization. Dissolved Fe increases d u r i n g the s u m m e r m o n t h s presumably because o f the f o r m a t i o n o f organo-meta]hc complexes. R,esulL~ o f ion-exchange and G F C e x p e r i m e n t s , which allow differentiat, mn between morganm and organic" trace-met, a] species (Means e t a l . , 1977), indl cat,e that, up to 6 0 - 7 0 % o f the dissolved Fe present is assocLated w i t h orgamcs d u n n g the s u m m e r months. In shallow g r o u n d water such as in bogs aJld seeps

121

where DOC concentrations may approach 10 ppm and more, organic Fe is also quantitatively significant. During the winter, this association decreases to 5-- 10%, mainly owing to the decrease in DOC (J.L. Means, D.A. Crerar and J.L. Amster, unpublished data, 1977). An interesting characteristic of Pine Barrens streams is that during the summer, stream bottoms become ubiquitously coated with a red amorphous Fe(OH)j precipiLat,e which ts not present, during the winter. Because of the simdarities between t,hts precipitate and bog tron, study was undertaken to det,ermme why deposition oCCUlTed pr~lominant, ly in the summer. The objeer=re was to evaluate whether flocculatlon was occurring inorganically that ts, whether the solubdtty product of amorphous FetCH)3 wa.s being ex ceeded, or whet.her precipiLat,=on was being aided by a catalyst such as Fe ox ,d iz=ng bac Leria. For this purpose, a compuLer prograni was devised. Gtven Eh, pH, iontc strengl,h, and various ligand concentrations such as SO,~, F and C I , the program predicts the theoretical equilibrium solubUity of Fe using amorphous Fe(OH)I ms a reference solid. Concenl:rations and activities of 25 simple and complex ions are computed by this pro~am. The theoretical solubility can then be compared to the measured dissolved Fe concentrat,on of the sample. SLability const.,nts used in the program for the Fe complexes were obtained from Smit, h and Mart,ell (1976) and Nordstrom and Jenne (1977). By eom paring Fe equilibrium at, a given station at, different, ttmes of the year, it, couJd be determined if there was any se&sonal influence on Fe solubtlit, y, i.e., whether the observed summer precipitat,e could be justified by purely in organic equillbrm. Similar computations may be earned out, using the puhhc. ly avaJlable program of Plummer eL at. (1976), although this does not use all Fe species considered here. The ratio of measured to theoretical Fe solubili~l was determined for samples from both C,edar Creek and Mullica River. In all cases, streams were close to saturatmn with respect to amorphous Fe(OH)~. Measuredltheoreti. ca] Fe solubility rat,ms generally follow the pH trend, higher solubdity ratios being measured at, ttmes of htgher pH. The seasonal effect of Eh variations was of secondary significance. Solubility ratios are therefore generally higher during the summer when dominant, F e ( O H h precipitation is observed, but, are also equally high dunng some wmt,er months when little FetCH )1 flocculat.ton occurs. Tile sltghtly lower summer Ell tends to part, tally counterbalance the effect, of elevated pH. Inorganic Fe equilibria consequently do not, account for the observed temporal precipitation of Fe(OH).~ on stream bottoms in either the Cedar Creek or Mullica River draJnage basins. In both drainage basins preopitation of Fe(OH)~ during certain winter months is predicted. Furthermore, natural pH trends in the Pine Barrens are thought, to be now obscured by agricultural activity. In similar coastal plain environments w=th less agncult-ure, summer pH is typwally lower than winter pH because of the higher organic-acid con tents m summer waters (Beck el, al., 1974). In t,his case, the degree of Fe saturation would be actually higher in the winter than m the summer, and bog iron would be predwted t,o precipttat,e predominantly tn the winter, contrary

122

to observaUon. Thin is partmularly true or bogs ,n our study area where summer pH tell t,o values as low as 3.5 causing undersaturatmn in Fe(OH)~. Yet abundant, Fe was observed prec,p=tating in these same bogs during the summer. , n the other hand, Fe-ox=d,zing bacteria are abundant, in Pine Barrens surface waters only during the summer and are metabolically most act,we during th=s penod of maximum Fe deposition. While this does not, prove that Fe precipitation is organically catalyzed, bacter,al oxidation may present, an alternaUve explanaUon. Gro~ind w a t e r

ALl ground-water samples =n Table II were obtained from the Mullica R.wer area. Deep ground wat,ers were collected rrom either the Cohartsey or Kirkwood Format=ons in wells screened at, depths ranging 3 5 - 7 6 m. Shallow samples came from the Cohansey using wells screened anywhere from 3.0 to 15.2 m, mostly m the 6 . 1 - 7 . 6 m range. Since samples were collected during a two-month period, no seasonal trends have yet, been observed. However differences in wat,er composition as u function or depth are evident,. Deeper wound water tends t,o have higher pH, shghLly lower Rh, lower TDS, lower DOC, and higher Fe than shallow ground wat,er. The lower pH of shallow ground water is believed to be caused by addit, ion or CO2 from plant respiration and bacterial decay, and t,he shght, ly htgher Eh of the shallow waters is likely due to ae.raL=on. DOC in shallow samples =s on t.he average somewhat I'ugher, probably due t,o addit, ion from overlying bogs and soil. Analyses of other gr~.~und-wager const,=t,uents such as aJka.Lis, alkahne earths, morgamc amons, Fe, and several trace metals are available elsewilere (R.ush, 1962; r)onsky, 1963; Clark et, al., 1968; Anderson and Appel, 1969; Lungmuir, 1969a, b; R,hodehamel, 1970, 1973; Anonymous, 1976; Farlekas et, al., 1976). Fe values approaching 50 ppm, far exceeding t,he max=mum Fe concentrat,=on o1' 3 ppm encountered m this st,udy have been reported ['or relat=vely sllallow samples from the Cohansey and Cape May aquifers (R, ho. dehamel, 1973). Considenng the low solubility of Fe at, pH 5 - 7 comput,ed for these ground waters, it, is I=kely that these high Fe concentrations, ,1" analyt,caJly va.lld, primarily represent, part, icu.lat,e Fe. The comput,er program employed m studying Fe equdibria in the sLreams was also apphed t.o the ground wat,ers. Whereas the obJect, lye above was to evaiuat, e the seasonal precipitat,,on of Fe on stream bottoms, the goal m a p plying the progranl to ground water was to det,ermine whether Fu solubiUty decreased with decreasing depth of grotmd water, a prerequmite t,o the classLcal theory o1" inorganic bog iron deposit,,on. TheoreticaJ Ft-, solubd=t, ies obtained on some I U - 1 5 ground-water samples represented in Table II were all undersaturated in F'e(OH)~ (amor.) and showed no consistent pat.t,em of decreasing solub,lit, y of Fe with decreasing depth. Though deep ground wa Lers generally had lower gh than sha.IJow waters, the pH of shallow samples was significantly lower than that. of the deep. The increased solubil,ty of Fe resu.ltmg from the relatwely lower pH of" the shallow wat,ers out, wecghed the

123

decrease in solubility caused by their slightly higher Eh. That is, Fe solubility was actually higher in shallow ground water than in deep, although it is the shalJow ground water from which bog iron is precipitating. The classical explanar]on of bog-iron formation, that o1" Fe(OH)~ precipitating from ground wat,er whw.h becomes progressively supersaturated in Fe with decreasing depth, is therel'ore not corroborated by these calculations. However, locales of bog-=ron precipitation all share in common one other factor, the presence of Fe-oxidizing bacteria, which are capable of providing the necessary taralyst for bog-iron I'ormation. BACTERIOLOGY

Samples of water and freshly precipitated oxides were analyzed for bacteria both microscopically, and, in two instances, using species specific culture media. Mmro~opic examinations were performed at, 1200 power using Nomarski ~b'~interference optics. Known Fe-oxidizing bacteris which were positively identified in our samples included Thiobacillus l'errooxidans, Leptothrix ochracea, Crenothrix polyspora, Siderocapsa geminata and Metalloge nium sp. Naumaniella sp. was tentatively identified, as were Toxothrix and Gallionella which could also be possible pol y m orphs of Melallogenium induced m laboratory culture. Thiobacillus/'errooxidans is a small (0.6 X 1.6/~m) rod-shaped organism see Levy. et al. (1973). It is exceptionally acidophilic with a typical wable pH range 1-4.6, growth being poor above pH 4 (Lundgren et al., 1974). It, is an obligate chemolithotroph; that is, it must produce metabolically use~1 energy from Fe or S oxJdation (Walsh, 1978). This organism, though rare, was .positively identified in a few subsurface water samples from the New Jersey locality by growth in the spec=es.spec=fic " 9 K " medium or Silverma.n and Lundgren (1959). Crenothrtx polyspora =s characterized by unbranched rilaments up to ] cm long and 1 - 6 pm =n diameter sun'ou.nded by very. thin colorless sheaths often entrusted with Fe or Mn ox=des at. the base (Wolfe, 1960; H=rsch, 1974). (.?ells within the filament are roughly reef,angular, and approximately 5 pm in diameter. The organism is found m waters containing organic matter and dissolved Fe (Hu'sch, 1974). At the New Jersey locality, Crenothrix =s commonly attached to submerged plant.s. Fig. 5A is an example in an untreated water sample from the Batsto site. Leptothrix ochmcea displays sheathed straight rods (0.6-1.5 × 3 - 1 2 , m ) , often coated with Fe or Mn oxides (MuJder, 1974). Natural growth in Fe-containing wat,ers is accompanied by voluminous, flocculent masses o1" Fe(lll) oxyhydroxide containing numerous yellow-brown, short, smooth empty sheaths (Harder, 1919; Mulder, 1974). Fig. 5B is a photomicrograph o1" an untreated water sample from the BaL~to site, showLng an empty Leptothrix sheath, common in both surface and subsurface samples. Siderocapsa gerninata typically occurs as capsulated paired cells, the capsule being ? - I 1 pm in diameter and often stained brown by Fe and Mn

12,-I

Fig 5 Photomtcrographs o1' ( A ) Crcnoth~ polysporo, (B) Leptothrlx ochraceu, (C) SJderocapsa geminala, and (D) Fe~oxidizing Metailogenium sp. in u n t r e a t e d surface w a t e r ,samples

125

oxides (Skuja, 1974). Fig. 5C, a m=crophotograph of an untreated subsurfacewater sample, shows a high concentration of this orgardsm. Naumaniella, like 8iderocapsa is capsulated and stained yellow, but, cont,a.ins single, rod-shaped ceUs (Zavarzin, 1974). According to Zavarzin (1974) this organism can decompose organic complexes of both Fe and Mn. Naumaniella was tentat=vely identified in subsurface water samples from this locality. Welsh and Mitchell (1972a, 1973) have isolated an Fe.oxid=zmg organism they termed Metallogenium which is morphologically similar to GaUioneila ferruginea as described by Balashova ( 1 9 6 8 ) a n d Zavarzin and H irsch (1974). These organisms grow as twisted fdaments enerusted with Fe(lll) oxides, and lack convention'aJ cell walls. The Walsh and Mitchell Fe.oxidizing Metallo. genium grows in flocculant Fe(lll) precipitates and tolerates pH values 3 . 5 6.8 with an optimum at, 4.1. Fig. 5D, again of an untreated surface, water sample from our locality, shows organisms corresponding morphologically to either Gallionella [erruginea or to the Fe-oxidizing Metallogenium, aJ though terminal cells often described on Gallionella are absent. The same water samples were used t,o inoculate Welsh and Mitchell's (1972a) Metalloge. nium Isolation medium. A 1-ml moculum was added to 30 ml of culture medium, and serial transfers were made at, 72-h intervals. After five transfers the surviving organisms were photographed as in Fig. 6C. Addition of 100 units/ml of penicillin G to this medium did not affect growth, and we conelude, following Walsh and Mitchell (1972a, 1973), that the organism is Metallogenium, and not, Gallionella [erruginea. Small chips of bog iron approximately 0.5 cm square were Au-plated for scanning electron microscopy (SEM). Textures and structures strongly resembUng bacterial morphologies were common on almost all samples exam [ned. For example, Fig. 6A, taken at, - 20,000 X, reveals a structure approximately 0.65 pm in diameter which could be a fossilized Leptothrix sheath. Similarly, Fig. 6B and D show structures resembling the twisted filament and "rose-garland" morphologies of Metallogenium. Microfossils of Leptothrix morphologw, such as that in Fig. 6A have been noted in bog iron since as early as 1910 (Molisch, 1910). However, the bogiron mierofossils of Fig. 6B and D represent, a new discovery. The presence of these microfossils and the profusion of bacteria-like structures in the limo. mt,e malsrix suggest a strong association between bacteria and bog-iron deposition. DIBCLISSION

Source o[ iron The first, problem I,o be addressed is the source of the anomalously high surface concentrations of Fe in the study area. As shown =n F=g. 2, the topmost Cohansey and Kirkwood Formations are relat=vely clean and chemically mert quartz sands. Soil horizons, where present, at, all, are thin and poorly

1~6

A

, i.OFm

,

I.

Pig. 6 A B and D. Scanning electron mlerographs of bog iron maLrix showin6 probable blogenic structures C Phol,omicrograph of baeterlum I'rom surl'ace water samples grown in Melallogemum molahon medium

127

developed. Hence one musl, look t,o a deeper source for F'e, and this is likely provided by the underlying glauconlte and beds enriched in pyrite, siderite and vivianit,e. As previously noted, streams and bogs in I,his region are fed largely by ground-wat,er baseflow. At, a number of Lhe ground-water well sites sampled, wat,er levels were higher in wells screened at, great,er dept, hs ('-'60 m) t,han in adjacent wells screened at, lesser depths ("'/.6 m), indlcat, m g a t,endency t,owards net, upward flow. Water levels from an earlier network of observat, ion wells in the Cohansey I~'ormation near Bat~,~t,o were reported by Lang (1961) and Lang and Rhodehamel (1962) and support this conclusion - that ground-water flows both lat,erally and vertically into the Mu.llica RAver. As discussed previously, ground waters sampled in t,he present, sLudy with. m t,he Mullica R,iver drainage basin were consistent, ly acidic, ranging from pH 4 . 3 - 4 . 4 for shallow weUs ( 1.5--"/.6 m) t,o pH 4 . ' / - 4 . 8 for deeper wells (> 60 m). Sources of this aCldlt, y could include sulfat, e from rainwater and pyrit,e oxidaLion, trace organic acids, and 0 0 2 from organic decay and plant, respiration, the lat, Ler presumably being most, imporLant in t,he shallower, more acidK~ waLers. As previously noted, these acidic corrosive ground waters are undersaLuraLed in F'e(OH)~ (amor.) while carrying up to several ppm of the meLal. These waters ascend from underlying F'e.rich st,rata, providing the most, likely source of the Fe in surface streanls and hogs. In addiLion, ground wal,ers migrat,ing lat,erally east, ward could carry. F'e dmsolved from updip F'e. rich strata to the west, (see Fig. 3). Iron-oxidation kinetics Wtlile sampled ground wat,ers are undersat, urated in Pe(OH)j (amor.), surface waters carrying only sUghtly lower concentrat,ions of Fe are roughly saturat,ed in Lhe metal. At, first, sight, t,hen, it, would appear t,hat F'e oxides must, simply precipitate as undersaturated ground wat,ers become aerat,ed in surface st,reams and bogs - t,his is the classical model of bog ore format, ion. However, t,here is a kinetic d i f f i c u l t y here owing to Lhe acidity of the surface wat,ers. The measured pH of river, bog and shallow ground-waLers averages about, 4 . 3 - 4 . 5 during t,he summer when oxide accumuJat, ion is greatest, and concentraLions of humic and fulvlc acids are high. The problem arises because the oxidat, lon of the ferrous ion, Fe"', is inordinat, ely slow below pH 6 (St,umm and Morgan, 19'70, p.534). Por pH values great,er t,han 4.5, the rate of ox=dation of F'e~' in abioLic systems follows the lunet, lc relationship: -dlFe2'lld/

= k [Fe'~'l [ O H 12po.2

(1)

wherel,, = 8.0(±2.5). I 0 I'~ I ~ mole-" arm. -I rain -I at, 25"C. Below pH 3.5, l,he rate law is independent, of pH:

- dl Fe'2' I Idt = k'[ Fe ~' ] PO,~

(2)

12~4

where I," = 1.0 • 10'7 a L m . ' i n t n ' at, 25"C ( S t u m m and Lee, 1961 ; Singer asld

St,umm, 1970). Note that according to eq. 1, a 100-fold increase in the rate of o x i d a t i o n occurs wtt, tl a unit iricrease in pH. Assumiilg rate law ( 1 ), and pH = 4 . 5 , P O , 2 = 0.2 arm., and [ Fe"'l = 8 . 9 . 1 0 ~ tn (or 5 ppm), gives the impossibly slow rate dl Fe '~* I/dt = 8.0 • l t r " ppm mm -~ , or a half-time for Fe"' o x i d a t i o n o f 300 days. iHaJf-tlme is the t,tmP required t,o oxtdize ont-, half o f the ferrous ion at any given starting c o n c e n t r a t i o n . ) By cont, rast, at, pH 7, Fe z. o x i d a t i o n occurs at, 0.8 ppm Illln I , with a |lalf-t, tme of/.1.3 mill, all olse being the same. Thus, it would appear that Fe ~' o x i d a t i o n should he t,oo slow m the acid waters o f tile study area to p e r m i t significanl, accumula tlon of hog iron. An additional catalytic mechanmm is clearly required. Muctl the same a r g u m e n t applies to the problem ol' acid mine drmnage. In this case tile o x i d a t i o n of p y r i t e follows a four-step cyclical s e q u e n c e ( S t u m n i and Morgan, 1970, 19.540)' -, is) ÷ 3.5(:1, + H,(_)~-Fe"' + ,2S(.),~ - , - 2 - + 2H' FeS,

(3}

2 F e " ' ÷ 1i.5(-),, + 2 H ' = ' 2 F e ~' + H,,()

(4)

Fe ~' + 3H:C)~ Fe(C)H)~ is) ÷ 3 H ' i

~

I;eS., (st + 1 4 F e '

t

(5) I

",l -

~-

+ 8H,,(:) ~- l S F e " ' + 2S(.)4

-I- 16H

t

(ill

Here, react, ran 13) rod,rally t,riggers the pr,.Icess, (5) precipitates amorpht~us Fe oxides, and (6) dissolves addittonal pyrite by Ft-," reduct,ion Steps (3) (5) and (6) release acidity, ,fft,en creating pH values as low as 2 ,.)r 3. LInder such acid ,,t, ndlt, ioris, reaci,t,_m (4), ,~i' the oxidat, i,:m o f F e : ' . IS ex,.'eedmgly slow um'e agmn, and beconles the overall rate Iimit, lng step. Reaction 1,4 ) may be catalyzed hy light, but, only by a factor or' '), - 3 ' times; it, may also be catalyzed by surface area c o n c e n t r a t i o n s exceeding 100 m" I ~, by soluble F e " , C u " ' , MI1 '+, Co ~, and AI TM , and by microbial act,~vit,y. These catalysts tlave beerl t,ested by Singer and St, tmlm (197171) who stll~wed that, t,he elTect of bact,erla far outweighs "all others u n d e r naturaJ c o n d i t i o n s In ract,, I,hey found that, microhiM act, iviLy couhl accelerate Fe"' uxidat, lon t'ly m,~re t,ilan six orders of m a g n i t u d e at acid pH.

Bacteriological controls In rivers pollut.ed by acid m m e d.rmnage, the I"~aet,erlun~ Tlltobaclllus I'erro oxtdans exerts the prime c o n t r o l on react, ion (4), and w i t h o u t this organism t.he acid mine llroblem w~luld |)e far less severe ( L u n d g r e n et ai , 1972; Walsh asut Mitchell, 1975, Walsh, 1978). However, T. /'errooxtdans is e x t r e m e l y acidophdtc, growth being p o o r above pH 4. In the legs acidic wat,ers (~f the New ,Jersey Pine Barrens Thtobaczlh~s is present, b u t rare. (.)n the o t h e r hand, Metallogenium, wlt, h a kq'owth o p t i m u m at, pH 4.1 is commo=l, as are Stdero capsa and Leptothrtx. In addlt, ton, st, ruct, ures resembhng Metaliogentum and Leptothrtx "are preserved m the bog iron itself ( Fig 6A, B and D). Finally,

129

as discussed previously, the streambed precipita, tion of lee shows a strong seasonaJ dependence, being far more pronounced in the warmer months and almost negligible in the winter when batter=at counts are also at, a minimum, This all suggests that, bacteria serve as the necessary, catalyst for reacUon (4) - t,he rate limiting oxidation of ferrous to ferric ion. Amorphous lee(ill) hydroxides would then precipitate according t,o reactton (5) with a net, gaJn of 2 mole H * for every mole of lee 'z' oxidtzed, lee precipitation thus contributes, aJong w.th soluble acids, and COz, to the observed acidity of surface and shallow ground waters. In the Pine Barrens locality, react-ions (3) and (6) are less important, except as a possible local source of soluble lee and sulfate where underlying st,rata contain traces of pyrite. The concluston that bacteria serve as catalysts for lee oxidation may aJso be reached by a process of elimination. Aside from the lee-oxtdizing bacteria, no other sLut,able catalysts seem t,o be available at, t,hm IocaJ=ty. LInl=ke Mn oxides, freshly precipitated amorphous lee hydroxides are not, autocatalytic (see review by Crerar eL at., 1979a). Surface-area concentrations exceeding 100 m" I I of catalyzing materials such as clays are not available on stream beds or at, shallow depths i.n the Cohansey leormatton which, instead, consists of well rounded pebbles and sands. As shown in le=g. 4 even bog Lron collected from swamps tn the region consmts of relatively coarse quartz sands (rather than clays) thickly cemented by ILmonite. Stumm and Lee (1961) showed that concentrations of transition-metaJ ions such as Cu z*, Mn ~' and Co ~° on the order or 1 ppm can signiricantly accelerate leer' oxtdatton. However, concentrations of metals other than lee are too low tn these surface and ground waters to effect the orders of magnitude changes required (see Table II). Stumm and Lee also showed that concentrations of CI" and SO~ on the order of 100 ppm had no measurable effect on the oxidation rate. The major dissolved components of these waters are humic and fulvic acids at concentra. tions ranging 1 - 5 0 ppm. Thets and Singer (1974) have demonstrated experimentally that simtlar concentrations of humic and related acids such as tan mc acid, glut, amine, vanillic and citric acids will notably retard the oxidatton of the ferrous ran. This is probably attributable to the formation o1" kinetitally stable lee(ll)-organo complexes such as those predominating in this region. In addition, Theis and Singer showed that the same orgamc acids will rapidly reduce any lee(Ill) which might be formed by reaction (4). This underscores the need for additional, blologwal cal,alysts. According t,o the classic paper by Harder (1919), the associaUon o1' leeoxidizing bacteria with bog ore deposits ha.,~been reco6mized since 1836. There is also an int,eresting early discusston on the relation between bacteria and bog iron by Dake (1916). [n a study of bog iron deposits in swamps at I.he head of the Snake River, Colorado, Deul (1942) identit'ied abundant growt, h of the lee-oxidizing bacteria Gailionella, Leptothroc, CrenothrLx and Sphaerotilus. Deul concluded t,hat, these deposits were biogenm based largely on t,heir visible assoctation with large bacterial colomes. Historically, the term "bog ore" ha,,~been applied to a wide range of fresh-

I 3U

water Fe.rich deposits. As summarized by Callender a.nd Bowser (1976) these include deposits m soils, springs, bogs, rivers and lakes. These may vary. in texture from the coatings and entrusted sands st,udted here, to the thick crusts and concretmns characteristic of northern lakes. Bacteria assoctat, ed wtt,h the latter lake deposlt,s have been dmcussed extensively by Perl'il'ev et, ',.d. (1965) who showed that 8~derococcus, (Talhonella and similar Fe-spectric organisms precipit,at,e Fe, whtle Mn oxidizing genera such as Metallogemum, Caulococcus and Kusnezov,a accelerate preciptt,atton of associated Mn ox tdes. A t,hermodyna.mtc model for the biogenlc depositmn of Mn has been developed by Crerar eL aJ. (1979b) and may be applied by simple analogy to the Fe oxides.

Metabolic considerations It, ts not, known m all cases wheUler Fe.oxJdizing bacteria denve metaboltcagy use~l energy I'rom the precipitat, lon of Fe. Silverman and Ehrlich (1964) have proposed that such bacteria mtght, ox=dize Fe by: ( 1 ) direct, enzymatic activity; (2) digestion or orga.no metallic complexes leawng behind the metallic precipitate as waste; and (3) interact, ion wtth end-products of metabolic activit.y such as ammonia and organtc bases whsch raise local pH and precipitate metal hydroxides. C)f the bacteria observed in the Pine Bar tens samples, Thlobac=llus/'errooxldans m an obligate chemolithotroph that ts, it, derives 'aLl its met,aboUt energy rrom the enzyTnatic oxidat, mn of Fe and S; it, will kq'ow, but, only wtt, h extreme reluctance, on purely orga.ntc med=a (Kegy, 1971; Lund~en eL aJ., 1972, 1974). Gallioneila, Leptot, hrbc and Metallogenzurn have been described as renault,aLive autotrophs m that they appear capable of denying energ'y either from the ox=datton of organic matter or of Fe (Ehrlich, 1972; Welsh and M=t,chell, 1972a). It, is beheved t,hat. CrenothrLx and Siderocap~ may not, oxidtze Fe directly, but, may either adsorb femc ion on their cell surfaces or sheaths, or may oxidi],e the organtc motety of an organo-Fe complex ( Ehrhch, 1972). Direct, enzymatic oxidation of Fe ~'' is a surprisingly mefl'icient source o1' energy relative to the more usual heterotrophic oxidation of organics. For example, the oxtdat, ion o1" Pe ~' ma the summation reaction: Fe ~ + 0.250, (g) + 2.5H2(') --, 2H* + Fe(OH)~ (amor.)

(7)

releases a.n energy of only about, 10.4 keel/mole Fe '2' (assuming POz = 0.2 atm., pH = 4.5 and Fe = 5 ppm). In contrast, the het,erotrophic o l i d a t t o n of glucose: C~,H,~(.'L, ÷ 602 -' 6C(-)., + 6H,,C) (I)

(8)

releases 677 keel. per mol.e of glucose (assuming roughly equal CO~ and C)~ concentrations). Pollowing St,umm and Morgan ( 19'70, p.55'7) and assuming a 36% erfie=ency m microbial energy conversion, then 140 g Fe z, must, be ox=dized t,o convert, 1 g CO,, to cellular carbohydrate [by reversing react,ion

131

(8)1. Hence chemolithotrophs such as Thiobacillus must, necessarily oxidize great quantities of Fe - quantities sufficient to produce li.monitic bog ores or thick streambed deposits at acid pH. There is no direct evidence that any of the bacteria described in the Pine Barrens deposits can oxidize Fe by either of the two remaJnmg mechanisms - dtgesl, ion of organo-metallic complexes or interaction wtth end products of metaboLic activtty. In view of the high concentration of organo Fe corn plexus in the Pine Barrens streams, the first alternative seems particularly attractive. This mechanism was first proposed by Harder in 1919 for the htogenie origin of bog iron. However, humic and fulwc acids wl'uch are the prune organic c.omponents in the study area, are themselves the end-products of decay reactions and are highly resistant t,o further bactena.I ati,ack (Kononova, 1966, p.44; Jackson, 1975). In addttion, the data of Walsh and Mitchell (1972a) suggest, that mild complexing agents such as KHphthalate efI'ectively isolate Fe(ll) from the metabolic activity of Mct,allogenium. F. Walsh (pers. commun., 1977) has observed similar inhibition with formic and tannic acids and EDTA, all suggesting that, Metallogenium, at, least,, does not precipitate Fe by Harder's mechanism. The organism Thiobaciilus [errooxidans, which displays optimal acttvtt, y at, pH . 3.5, is not, as important in the study area as is Metallogenium with a growth optimum at pH 4.1. Walsh and Mitchell (1972b) have suggested that acid mine waters are produced by a pH-dependent succession of iron bacteria, with Metallogcnium first catalyzing Pe 2' oxidation tn the pH range 3.5 -,5.0. As the system becomes more acidic due to activity of this organism, Thlobacillus/'errooxidans takes over creating pH values less than 3.5. Welsh and Mitchell ( 1 9 7 2 b ) s h o w e d t,hat Metallogenium mcreases Fe:' oxtdation rates and resultant acid production by a fact,or exceeding 200 over the pH ra.nge 3.,5-4.5. The succession t,o a more acidic Thiohacillus-dominated en w r o n m e n t does not, occur m the Pine Ba.rrens owing to the scarcity of sul fide minerals. The trace-metal analyses of bog iron previously quoted show that the processes prec.plt,ating oxides are highly specific for Fe. For example, the Fe/Mn ratio of the Mullica River averages roughly 3'7:1 while that of the bog u'on averages '7900: 1. It. has been argued thai, freshwater F e - M n depostts typtcally contaJn much lower trace-element concentrations than t,helr ma nne counterparts because the former are deposited much more rapidly. Thts leaves less t,ime for the selective adsorption of trace metaL,~ onto growing surfaces of freshwater deposd,s (Callender and Bowser, 19'76; Crerar et el., 19'79a). Thts effect, might, also he amplified by the activity of F'e-specific enzymes. For example, the Mn-oxtdizing bacterium Melailogemum personalure selectively precipttates Mn even when Fe concentrations are stl~mirtcan{,ly higher (Perfil'ev eL at., 1965; Crerar et at., 19'79b). This suggests that, Metallogenium oxidtzes metals enzymat, ically rather t,han by an alt,ernat.tve nonselecttve mechantsm. Microfossds strongly resembling M. pcrsonalum have been discovered in

L32

t,he cherts of baJlded won formaLlons as old as 1.9 Ga (see rewew by Crera.r

et, al., 1979b). Other mtcrofossds resem bhng Sphaerotilus, Galhonella and Crenothrix have been described in t,he same formations ( Barghoorn and Tyler, 1965; Cloud, 1965). It, ts possible t,haL these organisms or t,heir precursors act, ively precipitat,ed Fe oxides t,h r o u g h o u t the early history of life on t,hts planet much as t,hey do today. ACKNOWLEDGEMENTS

It. ~s a pleasure t,o acknowledge t,tle assist,a.nce of J. Amst,er, M. Borcstk, A Ftscher, R,. Klemmann, K. Lyon, M. Marsden, R. Quiel, t,, H. Sachs, and L. Williams w.thout, whom this sLudy could not have been completed REFERENCES

Ande,,on, H.R and Appel, C A , 1969 Geology and ground wat,er resource,~ uf Ocean Counl.y, New Jersey State N J Dep Conserv Eeon Dev D i v , WaLer Policy Supply, Spec Rep 29, 93 pp Anonymous, 1976. Water resourcesdat.a for New Jersey, wut eryear 19'76 LI.S. Geol Sure , Water Dal,a Rep NJ-76 1,766 pp Balashova, V.V., 1968,. T a x o n o m y of I,he genus Galhonella. Micrub=ology, 37 I-/7()-b98 Barghoorn, E S. and Tyler, S A , 1965 Microorganisms I'rom the (3unflint Chert Science, 147' 5 6 3 - 5 7 7 Bayley, WS., 1910. Iron Mmes and M i n m g m New Jersey, Vol VII Geol Sure N J, Trent, on, N.J , b12 pp Beck, K.C, Reuter, J.H. and Perdue, E M., [974. Orl,!,anie and inurgan,c geochemistry, ol some coastal plain flyers of the southwestern Llnited States. (3eochim. Ct~moehim. Acl, a, 38 3 4 1 - 3 6 4 . Braddock R.ogem, K , 1930 '?he bt~R ore industry ,n South Jersey prtor t,o 184b J Chem Educ.,7. 1 4 9 3 - 1 5 1 9 Callender, E and Bowser, C, J , 1976. Freshwater I'erromanganese dept~s,t.s In K H Wolf (Editor), Handbook of Strata Bound and Stratirorrn Ore DeposiLs Elsev,er, Am sterdsm, pp 34 ] - 3 9 4 Clark,(3.A,Meisler, H A , RhodeharneI, E C andG,II, H E , 1968 Summary of ground water resources of Atlanl, m County. N J. Dry Wat,p.r Resour., Cire 22, 53 pp Cloud, P E , 196~') Significance ol' the (3unl'hnt (Preeambr,an) mlcroflora Science, 148' 27-35 Cuonley, L S , Baker, E B and Holland, H D , 1971. Iron m theMulhca R w e r a n d i n Great, Bay, New Jersey (."hem Oeol , 7 : 5 1 - - 6 3 Crerar, D A , Corrnick, R K and Barnes, H L, , 19'79a (].eocherrustry o1' manganese. an overview. In: I.M. Vsrent.sov (Ed,t,or), Geology and Ceochemmtrv of Manganese, Vol I, Akad#.miaJ Kiado, .Budapest. (m press) Crerar, D A , P"ischer, A (3 and Plaza, C L,., 19'79b Melallu~enmm and biogenic deposi t,,on o1' manganese from Precambnan t.o Recent time In I M. Varent,sov (Editor), Geology and Geochemistry ol" Manganese, Vol III, Akad#m=a, Kiad6, Budapest (m press) Dake, C. I., 1916. The format, ran and dmtrtbut, ion ol bog =rtm ore dept~its. Am. InsL. Min Metail. PeL E n g , ' ? r a n s , 5 3 . 116-12,.I D~uI, M , 1942 The or,gin of the bog iron depos,Lu near MuqLezuma, Summit. Count, y, Colorado M Sc "l"hes,s, University of Colorado, Boulder, Colo , 3"/ pp D o ~ k y , E , 1963 Records o1' wells and ground waLer quality in (.?amden County N J Die Water Resour,C,rc !(),70 pp

133

Ehrlich, H.L., 1972 Iron, oxidatton and reduction-microbial. In: R.W. Fairbridge (Edit,or), The Encyclopedia o1' Geochemistry and the Environmental Sciences. Van Nostrand Reinhold, New York, N.Y., pp. 610--612 Farlekas, (3.M , Nemickas, B and Gill, H E , 1976 Geology and ground water resources ol' Camden County, NewJersey U.S GeoI. Surv.,Water Resour I n v e s t , 7 6 7 6 , 146 pp. Gay, S F , 1975. Precipitation chemistry and its relation to the river water chemistry of the New Jersey Pine Barrens. B.A Thesis, Princeton Univen~ity, Princeton, N J., 86 pp. Harder, E C, , 1919 Iron depositing bacteria and their geologic relations I.l.S Geol Surv., Prof Pap., 113, 89 pp. Hirsch, P , 1974 Crenothnx. In: R E Buchanan and N.E. Gibbons (Ed=tors), Bergey's Manual of Determinative Bacter.ology Williams and W.Ikins, Baltimore, Md , pp. 135- ! 36. Jackson, T A . , 1975 Humic matter in natural waters and sed.ments SodSci., 119: 06 r. ,_ 64 Kelly, D P , 1971 Autotrophy. concepts ol' lithotrophic bacteria and theirorgan.cmetabohsm Ann. Rev. M=crob=ol.,25' 177-210 Kelley, H M , 1971. A hydrologic and geochemical study or the New Jersey Pine Barrens B A Thes.s, Princeton University, PrinceLon, N J., 128 pp. Kononova, M.M , 1966 Soil (.')rganm Matter. Pergamon, New York, N Y , 544 pp. Lang, S M., 1961. Natural movement ol'ground water at. a site on the Mulhca R.ver in the Wharton Tract, southern New Jersey LIS. Geol Surv, Prof Pap, 424 D' D52-D54 tang, S M. and Rhodehamel, E C., 1962 Movement, o1" ground water beneath the bed o1' the Mullica River in the W~arton Tract, southern New Jersey. I.I.S Geol Surv , Prof Pap., 450 B B90-B92. Langmu=r. D , 1969a. Iron .n ground water of the Magothy and R.antan I'ormat.ons m Camden and Burlington C,ount=es N.J Div Water Resour, Circ 19, 49 pp Langrnuir, D , 1969b Geochem stry of iron in a coastal piton aquifer o1' the Camden. New Jersey area LI.S Geol Surv., Prol' Pap., 650C: C,224-C235. Langrnuir, D., 1971. E h - p H deterrninaLion. In: R E. Carver (Editor), Procedures in Sedimentary. Petrology Wdey.lntersc=ence, New York, N Y.,pp. 597-634. Levy., J., Campbell, J J.R and Blackburn, T H , 1973 ntroductory. Microbiology. Wdey, New York, N Y., 684 pp. Lundgren, DG ,Vestal, J.R andTab.ta, F R , 1 9 7 2 . The microbiology ol' mine drainage pollution. In R Mitchell (Editor), Water Pogutmn M.crobiology Wiley Interscience, New York, N Y , pp. 6 9 - 8 8 Lundgren, D (3 , Vestal, J.R. and Tab.is, F.R , 1974 The iron o~ad.zmg bacteria In: J.B Nedands(Editor),Mwrob.al Iron Metabolism AcademmPress, New York, N.Y ,pp 457-473 Means, J.L., Crerar, D.A. and Antster, J.L., 19'7'7. Application of gel filtration chromatography to evaluation of organo.metallic interactions in natural waters. Limnol. Oceanogr, 2 2 : 9 5 7 - 9 6 5 Minard, J P , Owens, J P., Sohl. N F , Gdl, H.E. and Mello, J F., 1969. Cretaceous-Tert.. ary boundary, in New Jersey, Delaware, and eastern Maryland U S Geol Surv , Bull., 1274 H H I - H 3 3 Mmard, J P., Perry, W.J, Weed, E.(3.A , Rhodehamel, E I , Robbms. E.I and Mi.xon, R, B, 1974 Preliminary report on geology along Atlantic continental margin of north eastern Llrdl,ed States. Bull. A.rn Assoc. Pet Geol., 5t~' 1169-1178. Molmch, H , 1910 DieEmenbakterien G Fischer, Jena, 83 pp. Mulder, E G , 1974 Leptothrix. In' R.E Buchanan and N E. (3ibbons tEd.tots), Bergey's Manual or Determinat=ve Bacteriology. Williams and Wilkins, Baltimore, Md., pp 129-133. Nordstrom, D.K andJenne, E A , 1977. FluoHtesolubilityequilibr.ainselectedgeo thermal waters Geochim Cosmoch.m Acts, 4 1 : 1 7 5 - 1 8 9

134

Olsson, R K , 1963 l,atest Cretaceous and earhest Tert=ary strat graphy of New Jersey coastal plain Bull Am. Aasoc Pet. Geol , 47' 6 4 3 - 6 6 5 ()wens, J P and Minard, ,I P , 1961') The Geo ogy o f the North C,entraJ Part of the New Jersey Coastal Plain John Hopkins Llniversit, y I~'eas, Baltimore, Md., 45 pp Owens, J.P and Sohl, N F , 1969 Shell' and delta,c paJeoenv'ironments in t.he Cretace ~us-Tc*rt=ary formations of the New Jersey Coastal Plain. In' S Sub,tzkv, (Editor), Geology o(' Selected Areas in New Jersey and Eastern Pennsylvania and Guidebook or Escursions R utgers I.Inivers, ty Press, New Brunswmk, N J , pp. 2 3 5 - 2 7 8 Perlil'ev, B V , (3abe, D R., Gal'per, na, A M , Rabinovich, V A , Sapotn,tskii, A A , Sher man, E E and Troshanov, E P , 196!:~ Applied Capillary Microscopy Consultants Bureau, New York, N Y , 122 pp P=erce, A I') , 195'7 Iron ,n the P,n~,s Rutgers Univers ty Press, N~=w BrunswLck, N J , 24,-I pp Plummer, L N , Jones, B.F. and Truesdell, A.H , 19'76. WATEQF, a c o m p u t e r program r u r c a l c u l a t . m g c h e m = c a J e q u i h b r i u m o f n a t u r a l w a l e r s I.IS Geol Surv,Wat,er Resour Invest., 76 13, 66 pp Rhodeharnel, E C , 1970 A I=ydrc~log,c an',dysiJ, o1' I he N~=w Jersey Pine Barrens reg=on N J Water R.esour ,C,rc 22, 35 pp RhodehameI, E C , 1973 Geology and water resources of the Wharton Tract. and the Mulhca R,ver basin m southern New Jersey N J. Lhv Water R esour , Spee P,.Pp , 36, !:~8 pp R,eha.rd~,, H G , 1967 Stratigraphy ol Atlant=c C,oastaJ PIA,n between Long bland and Georg=a. remew Bull Am A ~ o c Pet. G e o l , 51 24(.)0--'2429. Rush, F E , 1962 Records of wells and ground water quaJ,tv =n Burhngton County, New Jersey N J Day Water Resour , CLrc '7, 104 pp Silverman, M P and Ehrl,ch, H I. , 1964. M,crobmJ I'ormat,,cm ~ l d degradatu.m at' m,ner a.ls Adv Appl M,crob,ol , 6 15;'l-2(}6 S=lverrnan, M P and I.undgren, D.t.3 , 1969. St,ud=es on the chemoautotroph=c Iron bacte hum Ferrobnclllus [errooxidans. J Bacterial , 77 : 6 4 2 - 647. S,nger, P (~, and Stumm, W , 19'/(3. At,die m,ne dra,nage: t.he rate del,erm,ning step

Sc=ence, 167:1121-1123 Skula, H , 1974 Siderc~capsa In' R E. Buchanan and N E. t3ibbons(Ed,tL~r~), Bergey's Manual o r Determinative Bacl,er,ology Wilhams and W,Ik,ns, Baltimore, Md., pp. ,465-466 Smith, R.M. and Martell, A . E , 19'76. Critical Stability Constants, Vol. 4 InorgantcC.om plexes Plenum, New Yo=k, N Y ,2b'7 pp SI,a r k e y , J r , J A., 1962 The bog ore and b o g , r a n mdust.ryq~lsuut.h New Jersey Bull N,I Acad Sc,,'7 5 - 8 . S t u m m , W and Lee,(] F' , 1961 (Jxygenat=onq=l'l'errous=ron lad Eng Chem ,~l:.l |43-146 Stumm, W and Morga¢=,,IJ , 197(} A q u a t , c C h e m i s t r y Wiley Interscmnce, New Yc=rk, N Y , 5H3 pp 'T'helb, T I, and S,nger, P (~ , 19'74. 'T'l=e .,~tabihzat.,~n o1' I'errous lint= hv organ=c tun1 pounds ,n natural waters In P C. Stager (Edit,o=), T~ace Metals and Met.aI-C)rganm Int.eraet,ons,n Natural Waters Ann Arbor Sc=ence, An== Arbor, M i c h . , p p ;'103-32() T.~l.h, SJ. and Olt, A N , 19'72 Compos=t,,on of surface waLers of New Jersey in relahun to sod s*=r~es, I Waters o r the inner and outer coastal plaJnb Bull N ,I Acad Sc= , 1'7 2;1-;34 Walsl,, F', t9'78. B,ulogtcalcontrolsn mtnedramage In R M s t c h e l l ( E d , t o r ) . W a t e r Pc~I lut,on Microbmlogy, Vol I I . W i l e y Interscience, New York, N.Y., pp. 3 7 ' 7 - 3 9 ! WaJsh, F' and M,tehell, R , 1972a An ac=d tolerant, iron ox,diz,ng Met,,llr~gcmum ,I (3en. Mwrob,ol , 72 369--3"/:~ Walsh, F and Mstchell, R , 1972b A pH dependent success,anal'iron bacter,a Ear, run St'= Teehnol.. 6 8 t I 9 - H ! 2n

135

Walsh, F and M.Lchell, Ft., 1973 D.ITerentiat.on between GalhoneUa and Melallogemum Arch. M i k r o b i o l , 90:19--25 Watch, F andMttchell, R., 1975 Mine drainage pollution reduction by inhibition of=ton bacteria. Water Res., 9' 525-528 Woll'e, R..S, 1960. Observations and studies of Crenothrix polygpora J Am. Water Works Assoc., 52 9 1 5 - 9 1 8 Zavarzm,(3 A , 1974 Naumamella In: R E Buchanan and N.E Gibbons (Editors), Ber gey's Manual o1" Determinative Bacteriology Williams and Wilkins, Baltimore, Md , p 467 Zavarzin. G A and H=rsch, P., 1974. Galhonclla. In: R.E Buchanan and N E Gibbons (Editors), Bergey's Manual of Determ=native Bacterioloknj. W=lliams and Wilkms, Balti more, Md , pp. 163-165