GEOLOGICA CARPATHICA, 50, 5, BRATISLAVA, OCTOBER 1999
MINERALOGY AND GEOCHEMISTRY OF ACID MINE
Fe-PRECIPITATES FROM THE MAIN SLOVAK MINING REGIONS
, VLADIMÍR UCHA
and VLADIMÍR STREKO
Department of Mineral Deposit Geology, Faculty of Science, Comenius University, Mlynská dolina, 842 15 Bratislava, Slovak Republic
Geological Institute, Faculty of Science, Comenius University, Mlynská dolina, 842 15 Bratislava, Slovak Republic
(Manuscript received May 26, 1998; accepted in revised form December 9, 1998)
Abstract: The Fe-ochre precipitates from three mine districts of Slovakia (Smolník, Banská tiavnica and Pezinok)
were studied. The X-ray diffraction, electron microscopic methods (TEM, SEM) with elemental X-ray analyses and
the selective dissolution method were used to make mineralogical phase characteristics of Fe-ochre precipitates.
Many fresh precipitates are X-ray amorphous, but in the extremely fine-grained material it is possible to identify some
Fe-mineral phases like schwertmannite and ferrihydrite. In the strongly acid degraded and artificial soils mainly
amorphous ferric oxyhydroxide is found. Unstable oxyhydroxides, oxyhydroxysulphate and amorphous Fe-phases
were dissolved by acid ammonium oxalate solution (pH 3) and by 1 M HCl. All free iron (Al, Mn) compounds of the
samples were extracted by dithionite-citrate-bicarbonate solution. The extracts were analyzed for Al, Fe, Zn, Pb, Cu,
As, Cd, Mn by the AAS, AES-ICP methods. Samples with different contents of Fe-phases (1099 wt. % of samples)
and formed over a wide pH range (2 to 7) were analyzed. The ochres formed under strongly acid conditions contain
mainly high concentrations of Al. The ochres formed in slightly acidic or neutral conditions are enriched in Cu, Pb,
Zn, Mn and As. Such conditions were found in the drainage of inactive tailing impoundments. The element attenua-
tion by Fe-ochres are controlled to a great extent by pH and by sulphate concentrations. The comparison of oxalate
and HCl extract concentrations show that analyzed elements are attenuated by the active or poorly crystalline Fe-
phases to a great extent.
Key words: Acid mine drainage precipitate, aluminium, Fe/oxyhydroxide, mine acid water, mine waste pollution,
microelements, pH-dependence, poorly crystalline phases, selective dissolution.
Theoretically, the Fe-oxides/hydroxides or oxyhydroxides can
effectively adsorb our bind potential pollutant elements (met-
als) dissolved in waters (Cornell 1991; Schwertmann & Cor-
nell 1991; Schwertmann et al. 1979; Schwertmannn & Taylor
1989; Kooner 1992, 1993; Fuge et al. 1994). We are studying
the processes of Fe-oxyhydroxide phase formation in acidic
mine environments. Intensive pyrite oxidation in mine and
mine wastes can produce a large amount of free sulphuric acid
and/or extremely acid drainage water (pH < 3). These process-
es occurred mainly in sulphidic and coal mines (Jambor &
Blowes 1994; Alpers & Blowes 1994; Wieder & Novák 1995).
Acid water dissolves ore and rock minerals and the concentra-
tions of Fe, Al, Mg, Ca and metals (Zn, Cu, Mn, Ni, ...) in wa-
ter increased significantly. Fe (III)-oxides/hydroxides can be
precipitated after mixing or diluting the acid mine water with
fresh surface water and the characteristic red-brown (ochres)
Fe oxides are precipitated in drainage channels or other places
of mine water discharge (mine dumps, tailing impoundments).
The precipitates are very fine-grained and the high specific
surface of precipitates is one of the controlling factor of the re-
moval of the dissolved elements to the solid phase. However,
the formation of extreme acid mine waters has produced a spe-
cific or naturally unusual environment.
In the presented paper the formation of Fe-ochres in some
mine district of Slovakia is studied. The acidification of sur-
face water and soil is the serious environmental problem in the
vicinity of Smolník, Banská tiavnica-obov and Pezinok
mines, mine dumps and mill tailing impoundments (ucha et
al. 1995, 1997; Jako et al. 1997; Lintnerová 1996; Lintnerová
& Líková 1997; Trtíková 1997; Trtíková et al. 1996).
The aim of the paper is to identify the mineralogical com-
position of Fe-ochre deposits and determine the concentra-
tion of some environmentally important elements in their
precipitates from mine areas of Slovakia. Fe-precipitates se-
lected for the study were originated in various environments
such as drainage channels, soils, stream sediment and under
different conditions (pH, SO
Description of localities and samples
The studied Fe-oxide/hydroxide samples come from three
important mining districts of Slovakia.
1. The mine field of Smolník is situated in the Slovenské
Rudohorie Mts. (Eastern Slovakia, Fig. 1). The abandoned Cu-
Fig. 1. The localization of the investigated mine districts of Slovakia.
396 LINTNEROVÁ, UCHA and STREKO
pyrite mine (Bartalský 1993) is flooded and strongly acid wa-
ter (pH 2.83.8) discharges from the mine (Jako et al. 1996).
The Fe-ochre precipitates collected for analyses are formed
along the banks of the Smolník Stream, where acid mine water
penetrating into the stream is mixed with fresh water and caus-
es a dramatical decrease in its pH from about 7 to 4.04.5. The
Fe-ochres are also precipitated on the anthropogenic soil sur-
face (pH 3.4) of the Smolník mill tailing impoundment and in
the water drainage collector under the tailing impoundment
2. The mine field of Banská tiavnica (Central part of Slo-
vakia, Fig. 1). Fe-precipitates were collected from the aban-
doned mill tailing impoundments of Lintich and Sedem ien
and from the obov mine dump. A large amount of pyrophyl-
lite-pyrite gangue rock in the obov quartzite mine was exca-
vated and deposited on the dump. The intensive pyrite oxida-
tion in the dump produced extremely acid water (pH 1.72.4)
with a high content of total dissolved solids (ucha et al.
1997). Fe-oxyhydroxides are formed as the precipitates from
drainage water when it is mixed with the fresh water as well in
the degraded soils. The most acid soils (area of 35,000 m
desertified and deeply eroded.
Mill tailings of Pb-Zn ore processing were deposited until
1987 into the Sedem ien impoundment. The ochreous (ox-
isoil) horizons are formed in the soils in the vicinity of the
impoundment (Lintnerová & Líková 1997). Samples of
drainage precipitates and ochreous soils were collected
The mill tailing impoundment of Lintich has been inactive
since 1974 and no acidification processes can be detected there.
The surface of the impoundment is covered by the secondary
minerals (gypsum) and sometimes a hardpan with Fe-oxides can
be found in the near surface horizons. Higher contents of fresh
Fe-precipitates are formed in the drainage channel of the im-
poundment where they were collected (Table 1).
3. The Pezinok (pyrite-Au-Sb) mine field (Western Slova-
kia, Fig. 1). The Fe-precipitates formed in the drainage chan-
nel of the mill tailing impoundment of Kolársky Vrch and on
the stream bank near the abandoned pyrite mine (Augustín)
were analyzed (Table 1).
Table 1: The analyzed samples from Smolník, Banská tiavnica and Pezinok. The samples were collected in 1995 to 1997 from streams,
drainages and soils. More details about pH and extractable Al*-analyses can be found in ucha et al. (1997), Lintnerová & Líková (1997).
*A l(KC l) mg/kg
Stream sediment and
mine drainage precipitates (Sm/95, Sm/96)
Drainage water precipitates SmOd/96
Acid soils (ob/96, P/97)
Stream sediments (B22/97)
Anthropogenic soils (BA-BG 1997, 1996)
Acid soils (B/97, E/97)
Drainage water precipitates (1996,1997)
Stream sediment (Pez/96)
Drainage water precipitates (POd/96)
The X-ray diffraction analyses of samples were performed
on a Philips PW 1710 equipped with Ni-filtered CoK
tion and CuK
radiation. Transmission electron microscopy
(TEM) study was done on the JEOL JEM-2000 microscope
and elemental X-ray microanalyses using the 10,000 AN
LINKenergy dispersive analyzing system (EDS). Scan-
ning electron microscopes (SEM) TESLA BS300 and JEOL
JXA 840A were used for investigation of sample surface
covered by gold.
The field and laboratory pH measurements were done by
standard potentiometric methods. Soil pH was determined
after mixing the soil sample with distilled water and in 1 M
KCl (mixture 1:2.5). The treatment with 1 M KCl was used
for determination of exchangeable Al in the soil samples by
AES-ICP methods. The characteristic intervals of pH and Al
values are summarized in the Table 1.
Dried Fe-precipitates were treated by dithionite-citric-bi-
carbonate (DCB) at 85 °C (method Mehra & Jackson 1960;
Schwertmann & Taylor 1989; van Reeuwijk 1995). The less
stable or poorly crystalline and amorphous Fe-phases such as
ferrihydrite or schwertmannite (most probably together with
the amorphous compound of Al and Si) were extracted by
acid ammonium oxalate in the dark to eliminate photoreduc-
tion (van Reeuwijk 1995; Bigham 1994). Goethite, hematite
or well ordered lepidocrocite are not dissolved to any great
extent unless some source of Fe
cations is presented
(Schwertmann & Taylor 1989). Extractant was prepared by
mixing 0.2 M ammonium oxalate and 0.2 M oxalate acid so-
lutions. The 1 M HCl dissolution was applied to the same
samples as oxalate extraction. The HCl dissolves Fe and Mn
oxides (coating on the grains), carbonate and can also replace
trace element ions adsorbed on organic and inorganic materi-
al. Insoluble residues were determined gravimetrically.
Fe, Cu, Pb, Zn, Mn, As were analyzed in extracts by AAS
and Al by AES-ICP methods. The SO
the distilled water (Table 4, DCB-results) and in 1 M HCl ex-
tracts were determined by the gravimetric and colorimetric
methods. The Si was analyzed by the colorimetric method.
MINERALOGY AND GEOCHEMISTRY OF ACID MINE Fe-PRECIPITATES 397
Mineralogical phase analyses
The poor crystallinity and high variability in mineral phase
formation were characterized in the ochre precipitates formed
in a broad range of pH conditions. The majority of studied
samples were not pure Fe-precipitates and they contain com-
mon shale and soil minerals (mainly quartz, phyllosilicates
and +/- feldspar).
The sample set of the fresh precipitates and hardpan-like de-
posits of Smolník Stream represent a strongly acidic environ-
ment with high sulphate contents (pH in range 2.8 to 4.8, and
over 1000 mg/l of sulphates). The mineralogy of the sample
was characterized in detail by Lintnerová (1996). The most
common phase is jarosite which can be easily identified in the
X-ray diffraction profiles of all samples. Goethite was identi-
fied only in the hardpan samples and after oxalate treatment
of fresh sample (Fig. 2, sample Sm1/96). Amorphous and
poorly crystalline Fe-ochre phases such as schwertmannite are
dominant in the fresh Smolník precipitates (Fig. 2) and repre-
sent typical ochres formed under the condition of acid mine
drainage (Bigham et al. 1990; Murad et al. 1994; Bigham et al.
The Fe-ochres precipitated near the abandoned sulphidic
mine near Pezinok (Pez1/96, Pez2/96, Tables 1 and 4) are
formed at about the same pH conditions as in the Smolník
area. The X-ray analyses, TEM investigation and selective
dissolution results detected an amorphous to poorly crystal-
line character of the ochre material. The ochre forms aggre-
gates with elongated protocrystals 50 to 150 nm in size. The
surfaces of pyrite grains in the black shells are covered by
The ochre precipitates in the Banská tiavnica-obov area
are formed by stream-bank percolating and slightly acidic
5) (ob2/96 in the Tables 15). The X-ray pro-
files of precipitates show only one low and broad band
(0.2450.260 nm), characteristic for amorphous material.
The TEM micrographs show poorly crystalline material of
globular shape with needle-like protocrystals (Fig. 3). The
dominant Fe content with slightly increased Si and no S con-
centrations were detected in globular aggregates. Since more
than 80 % of the Fe-precipitates were dissolved by acid ox-
alate (ob2/96, Table 2) we assume that the precipitates are
of ferrihydrite-like character. Increased content of Si relative
to Al (Table 3) decreases probably the crystallization of pre-
The ochreous samples precipitated from the mill tailing
impoundment drainage (pH near neutral) were collected
from all three study area (Table 1). A high proportions of the
samples are amorphous to poorly crystalline Fe-oxyhydrox-
ide phases easily dissolved using acid ammonium oxalate
treatment (Table 2). The TEM micrographs (Fig. 4 AD)
show characteristic morphology of grain aggregates from the
Smolník and Lintich (Banská tiavnica) impoundment pre-
Fig. 2. X-ray profiles of the Smolník samples Sm1/96 and Sm3/96: natural and after acid ammonium oxalate treatment O. (Chchlo-
rite, Mmuscovite, Jjarosite, Qquartz, Ggoethite, Flfeldspar, Schschwertmannite.)
2 the ta, CoK
398 LINTNEROVÁ, UCHA and STREKO
Ochres in the soil samples
The upper ochreous (015 cm) horizon and the lower (15
30 cm) dark-brown horizon with local Fe-oxide aggregates
were created by acid leaching in the obov (Banská tiavni-
Table 2: The results of selective dissolution of the ss = stream sed-
iment precipitates, TI = tailing impoundment drainage precipi-
tates, soil and A = anthropogenic soil samples. Insoluble residua
(IR) were determined by the gravimetric method: the dissolved
part = (100-IR) wt. %.
Table 3: Large differences can be seen between Si and Al contents
determined in HCl and acid oxalate extracts in the Smolník and
obov samples (see also Tables 2 and 4). The ochre formed in neu-
tral impoundment drainage SmOd/96 has about the same Al
content in both extracts. ob2/96, probable ferrihydrite, contained
the lowest Al and relatively high Si contents.
Acid oxalate extracts
Table 4: The results of AAS analyses of DCB extracts. pH and
were determined as the distilled water extracts. 0values less
than the detected limit of the element in the extract. The results are
in mg of element per l kg of ochre.
Samples units mg/kg
0 1209 1128
ca) soils. Such soils are devoid of vegetation and the soil sur-
face is covered by gypsum and jarosite (Fig. 3A). Neoformic
pseudocubic crystals of jarosite can be commonly found in
the soil fraction < 2
m (Fig. 3 B).
Fe-oxyhydroxides coated the surface of soil particles repre-
sented about 20 wt. % of soil samples from the upper horizon
(Table 2). X-ray profiles of the soil sample show the broads at
d ~ 0.25 nm bands or an increased background but no crystal-
line Fe-mineral phase can be identified. Goethite is formed in
the deeper horizon of the soil but amorphous and/or poorly
crystalline Fe-phases are also presented.
The major part of the Fe-compounds are extracted by acid
oxalate (Table 3). Both samples come from the upper (025
cm) horizon and were sampled in 1996 and 1997 at the same
place. The same association of mineral phases was identified
in the acid anthropogenic soil of the tailing impoundment dam
(Sedem ien, Banská tiavnica). The dam soils are shallow
and no soil horizons were developed there. Tailing material
(fine sand) contains about 5 % of sulphides, mainly pyrite, in
the surface bed of the impoundment (below the shallow soil)
and sulphide oxidation is the source of extreme soil acidity
(Table 1). The pyrite grains are dissolved and Fe-oxyhydrox-
ides and sulphates coat the grains (Fig. 5B, C). The pH field
measurements document the increased tendency of soil acidifi-
cation and oxisoil horizon formation in the near-impound-
ment soils (Lintnerová & Líková 1997).
The Fe-compounds represent 10 to 25 wt. % of the soil
samples and a large part of the Fe-phases were dissolved by
acid ammonium oxalate (Table 2).
The tables (Tables 3, 4 and 5) contain the results of the
AAS-ICP analyses of the soluble Fe (III)-oxyhydroxide
phases. The results are expressed as element contents in mg
per kg of Fe dissolved phase, because the contents of soluble
Fe (III) phases are in the broad weight % range in our sample
set (Table 2). We can see, that the analyzed soil samples con-
tained only from 10 to 26 % of soluble phases but mine
drainage water precipitates contain much more of these phas-
es (48 to 99 %). The results in Table 4 are representative
analyses of DCB extracts from acid mine drainage ochres of
the Smolník, Banská tiavnica and Pezinok mine areas to-
gether with two analyses of degraded soil from obov (ob1
and ob3). Total soil analyses and mine water analyses from
the obov area (Banská tiavnica) presented by ucha et al.
(1997) are given in Table 7. The chemical characteristics of
the Smolník mine, stream water and stream sediments (total
analyses) are summarized in Table 6. The results of parallel
oxalate and HCl extract analyses of precipitates and soils are
presented in the Tables 5A and 5B. The relative concentra-
tion ratios (ochre/water) can be calculated for some elements
only and values with stars were used (Fuge et al. 1994).
Fe-phases are amorphous to very fine-grained (~ grain size
0.1 to 0.3
m) with high specific surface areas. The high spe-
cific surface area and high hydration of Fe-oxides are con-
trolling factors of the physical and chemical sorption or bind-
ing (mechanism and kinetic) of the dissolved elements. Other
MINERALOGY AND GEOCHEMISTRY OF ACID MINE Fe-PRECIPITATES 399
Fig. 3. obov ochre minerals. A. Jarosite as pyrite pseudomorphose in the obov soil sample. B. The typical neoformed jarosite crys-
tallized in pseudocubic particles. C, D. Ochre formed in slightly acidic drainage water, sample ob2/96. The needle-like protocrystals
(probably ferrihydrite) documented the crystallization stage of amorphous ochre.
400 LINTNEROVÁ, UCHA and STREKO
Fig. 4. TEM micrographs of mill tailing impoundment neutral drainage ochres. A, B. Amorphous to poorly crystalline ochres, sample
SmOd/96 (Smolník). C, D. The typical globular morphology of poorly crystalline ochre: sample Lintich, Banská tiavnica. Elongated ag-
gregates (4C) may be the result of bacterial activity.
MINERALOGY AND GEOCHEMISTRY OF ACID MINE Fe-PRECIPITATES 401
amorphous phases such as SiO
and Al-hydrated compounds
can be present and/or neoformed in the degraded acidic soils
as well. Unstable or intermediate phases of Fe (III) oxyhy-
droxide are dissolved by acid ammonium oxalate treatment.
The Si and Al contents in analyzed samples are listed in the
Table 3. 1 M HCl treatment led to the highest content of Si
and Al in solutions, probably due to much stronger attack not
only to iron ochres but to phyllosilicates as well. Only one
sample (precipitate formed in neutral condition SmOd/96)
shows about the same contents of Al in oxalate and HCl ex-
tracts. The analyses show, that the Fe-phases originated un-
der low pH condition contain mainly Al and other elements
are preserved in trace contents (Table 4). The variety of ele-
ments connected with Fe-precipitates increases with the in-
crease of the pH of their origins. High contents of Cu, Mn,
As, Zn were determined in the Fe-precipitates from tailing
impoundment (pH near neutral). The same pH-dependence
was observed for Fe-precipitates formed in acidified and an-
thropogenic soils (Table 5A, 5B).
The studied mine regions are badly polluted and the con-
tents of some dissolved elements are many times higher than
environmentally accepted values for soil and waters. It is re-
ally important, that neoformed Fe-phases can effectively re-
move dissolved and potentially toxic elements from the mine
waters. On the other hand, the amorphous character and/or
relative instability of Fe-phases indicate some possibility of
retrograde metal releasing reactions in strongly acid mine en-
vironments. Under common soil or water conditions such
retrograde reactions are highly improbable as goethite or he-
matite can bind or adsorb soluble elements to a great extent
(Schulze & Schwertmann 1984; Schwertmann & Cornell
1991; Schwertmann & Taylor 1989).
It is clear that not only high acidity, but also increased
amounts of sulphates and other compounds must be factors
controlling Fe-oxyhydroxides or oxyhydroxysulphates for-
mation (Bigham 1994; Murad et al. 1994; Bigham et al.
1997). Only small amount of goethite is present in the rela-
tively older hardpan such as the Fe-deposits in the Smolník
Stream (Lintnerová 1996). The sulphate contents in the
Smolník precipitates are still high and the mine water is
oversaturated with respect to schwertmannite (Cambier et al.
1997). Selective dissolution of the ochres samples by acid
ammonium oxalate has verified the mineralogical results.
However, interpretation of the partial extraction results of
natural samples is not as simple as could be expected. The
stream sediments and soils (tailings) contained other phases
such as organic matter and phyllosilicates partially leached
by acid water. The various elements adsorbed on these phas-
es can be removed by HCl and as well by organic extractants,
such as oxalate acid or citric acid (Schwertmann & Taylor
1989; van Reeuwijk 1995; Bigham 1994; Stumm &
It was found, that Al is enriched in ochres and the Al con-
centrations higher than 1 % were detected in some Smolník
samples. It can be expected, because Al is one of the most
Fig. 5. Banská tiavnica-Sedem ien mill tailing impoundment: A.
The surface of anthropogenic soils are coated by well crystal-
lized gypsum. B, C. Tailing pyrite grains are oxidized and second-
ary minerals are formed on the grain surface. The large number of
grain cracks are probably the result of the mill process.
402 LINTNEROVÁ, UCHA and STREKO
Table 5: The element concentrations analyzed both in 1 M HCl (A) and in acid ammonium oxalate (B) extracts of soil samples from the
Banská tiavnica mine area. 0less than 4000 mg/l in the extracts.
Acid ammonium oxalate
Table 6: Comparison of the Smolník Stream sediment, ochre and water analyses. Results of total analyses of stream sediments deposited
in the neutral and acid parts of the Smolník Stream (Jako et al. 1996) are in 1th- and 2nd-columns. Dithionite-citric-bicarbonate (DCB)
extract analyses of the same sample (Sm8/95) are given in the 3th-column. The acid water (4th-column) flowed into Smolník Stream and
ochres were precipitated (Sm2/95). The resulted stream water was still acidic (5th-column). The values with the stars are used in the ratio
calculation: Fe, As and Cu, were accumulated in the ochre precipitates.
(tot. anal. Sm8/95)
pH dependent element and it is well known and documented
not only in soils but also in acid mine drainage waters (Tho-
mas & Hargrowe 1984; Nordstrom & Ball 1986; Hsu 1989;
Fuge et al. 1984). The other analyzed elements Zn, Pb,
Mn are depleted in acidic ochres.
Some element depletion can also be seen in the total
stream sediment analyses (Table 6). For example, the Zn and
Mn contents decreased in the acidified part of stream as the
Fe-content (ochre formation) increased. It is possible, that
the sulphate acidoxidic water are leaching the stream sedi-
ment reached-up to the typical Smolník mine elements in the
past (Table 6). It appears, that As is relatively enriched in the
acid ochres (Table 6). Arsenic can be adsorbed and/or copre-
cipitated by ferrihydrite and Fe-oxyhydroxysulphates in both
As (III) and As (V) valence forms. Arsenic (V) forms strong
anionic complex with Fe-phases in strong acid and oxidic en-
vironments (Webster et al. 1994). On the other hand, the As
concentration in the mine water is really low (Table 6) and it
is possible, that as bound in ochres is released from sediment
suspensions (Morse 1994; Calmano et al. 1994).
The Cu and Zn contents in effluent mine water are relatively
high, but only Cu is relatively enriched in acid ochres (Tables
4, 6). The stream water (pH 45) analyses showed that Zn is
available for transport in acidic stream water (Kooner 1993;
Fuge et al. 1994). The ochres formed in neutral drainage water
attenuated large amounts of Zn, Cu, Mn and As (Table 4) and
clearly document that the water mobility of the studied ele-
ments is pH-dependent. The Mn and Al contents (Tables 3 and
4) are high and it is possible that Al-hydroxides and Mn-ox-
ides are created in these near neutral conditions. Important
MINERALOGY AND GEOCHEMISTRY OF ACID MINE Fe-PRECIPITATES 403
determined. The available Al increase in the soils and in the
neoformed Fe-ochres indicated the leaching of phyllosilicate
(Tables 1, 3, 5A, B). The soil minerals are possible sources of
Ca and K for jarosite and gypsum formation in the soils. The
sulphate enrichments in the acidic water can selectively immo-
bilize such elements as Pb or Ba to a greater extent than others
(Fuge et al. 1994). The some enrichment with Pb appeared in
the studied strong acid soils (Table 5A, B), but the no direct con-
nections with the sulphate content can be shown up to now.
1. The studied Fe (III) oxide/hydroxide precipitates from
the Smolník, Banská tiavnica and Pezinok mine fields
represented (X-ray) amorphous to poorly crystalline fine-
grained material. A major part of the ochres is formed by
less stable Fe-oxyhydroxide and oxyhydroxysulphate phas-
es, such as schwertmannite and ferrihydrite and by well
crystallized jarosite as well.
2. A high contents of jarosite and free and/or poorly crys-
talline ferric oxyhydroxide are formed (10 to 25 % of free
Fe- oxides/hydroxides) in the upper (oxisoil-like) horizons in
the strongly acid (degraded and anthropogenic) soils.
3. The Fe-ochres can adsorb or coprecipitate an important
content of dissolved elements and the attenuation of ele-
ments is pH dependent. The Fe-ochres formed under the
strongly acid conditions removed from solutions mainly Al
and the concentrations of other analyzed elements is relative-
ly low. The ochres formed under slightly acidic or neutral
conditions are enriched in their Cu, Pb, Zn, Mn and As con-
tents. Such conditions were found in the drainage system of
the inactive tailing impoundments.
4. The comparison of the concentration of the acid oxalate
and HCl extracts show that the analyzed elements are attenu-
ated by the active or poorly crystalline Fe-phases to a great
5. The element distributions in the Fe-oxides/hydroxides
formed in degraded or anthropogenic acid soils is controlled
to a great extent by pH and sulphate concentration, but other
factors can be important as well.
Acknowledgements: We are thankful Dr. ¼. Pukelová from
Geological Institute of the Slovak Academy of Sciences Brat-
islava for X-ray analyses and Dr. Èaplovièová and Dr. J. Stank-
oviè for their assistance in electron microscopy investigation
(Central Laboratory of Electron Microscopy of the Faculty of
Science, Comenius University Bratislava). We are grateful to
anonymous reviewers for their large effort benefited the manu-
script. This research was supported by Scientific Grant Agency
(VEGA) of Ministry of Education of Slovak Republic and Slo-
vak Academy of Sciences (Grant No. 1/4090/97).
Alpers C.N. & Blowes D.W., 1994: Environmental geochemistry
of sulfide oxidation. Amer. Chem. Soc., 550, 1681.
Banásová V. & ucha V., 1998: Degradation of grassland after
Table 7: The comparison of the obov water, soil (ucha et al.
1997) and ochre analyses. The values with stars are used in the ra-
P2 0-25 cm
proportions of the analyzed metals can be sorbed by organic
matter, as was detected by IR spectroscopy of ochre samples
(SmOd/96) and also earlier (unpublished data). These process-
es were not investigated, but we can note that the bacterially
catalyzed pyrite oxidation and increased organic contents in
mine water were documented (Jako & Cicmanová, unpub-
The extremely high As contents were determined in the
amorphous ochres precipitated in tailings effluent water near
the Pezinok mine (Table 4). The pyrite-arsenopyrite associa-
tion of these ores is the first factor controlling the such high
As re-concentrations in the ochre precipitates. On the other
hand, the effluent water of this inactive impoundment can
mobilize a high content of As.
Our first results indicated, that the Banská tiavnica mine
wastes deposited in the Lintich and Sedem ien impoundments
should produce drainage water with comparable high element
concentrations. The ochres formed in near neutral conditions
can be Mn, As, Cu and Zn enriched according to the mineral-
ogical composition of the processed ores and mine wastes de-
posited into the impoundment. Total and selective dissolution
analyses of waste drainage waters and Fe-ochres will be done
to investigate these processes. However, the ochre-phase anal-
yses of the antropogenic and uncultivated soils near the tailing
impoundment of Sedem ien indicated an element mobiliza-
tion and the main factor controlling the element mobilization
is the formation of extreme acidity (Table 1, Table 5A, 5B).
The soil like those of wetland are formed in the lower border
of the impoundment and as the soil acidity decreased in this
soil (Table 5A, 5B, sample BG/97), the Pb, Cu, Zn and Mn
contents increased. Wetland is a very effective system for re-
mediation of acid mine and tailing waters (Blowes et al. 1994;
The soil properties were monitored in the uncultivated area
around the obov mine in 1995 to 1997 and a high and in-
creased degree of soil degradation was identified (ucha et al.
1997). Acid water has flowed out of the mine dump percolated
into soils. On the one hand water with high contents of Fe, Al,
Mg, sulphate and other pyrite bearing metals has contaminated
soils and on the other acid-aggressive water has leached soils.
The free Fe-oxides have created a characteristic yellow-brown
oxisoil horizon. In the most acidic soils the increased contents of
exchangeable Al (Table 1 more than 1000 mg/kg in 1997) were
404 LINTNEROVÁ, UCHA and STREKO
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Note: This paper was presented at the Conference of the IGCP Project #405 ENVIVEATH, held in Bratislava from 24th to 26th November, 1997