The Role of Secondary Minerals in Controlling

8/17/2019 The Role of Secondary Minerals in Controlling

1/13

The role of secondary minerals in controlling the

migration of arsenic and metals from high-sulfide

wastes (Berikul gold mine, Siberia)

R. Giere ´ a,*, N.V. Sidenkob, E.V. Lazarevab

aDepartment of Earth and Atmospheric Sciences, Purdue University, West Lafayette, IN 47907-1397, USAbThe United Institute of Geology, Geophysics and Mineralogy, pr. Koptyuga 3, Novosibirsk 630090, Russia

Abstract

The role of secondary minerals in controlling the migration of As, Cu, Zn, Pb and Cd has been investigated in piles

of high-sulfide waste at the Berikul Au mine, Kemerovo region, Russia. These wastes contain 40–45 wt.% sulfides and

have been stored for approximately 50 a near the Mokry Berikul river. Sulfide oxidation generates acid pore solutions

(pH=1.7) with high concentrations of SO42 (190 g/l), Fe (57 g/l), As (22 g/l), Zn (2 g/l), Cu (0.4 g/l), Pb (0.04 g/l), and

Cd (0.03 g/l). From these solutions, As is precipitated as amorphous non-stoichiometric Fe-sulfoarsenates in the lower

horizons of the waste piles. During precipitation of the Fe-sulfoarsenates, the concentration of Fe in these phases

decreases from 34 to 21 wt.%, that of As increases from 11 to 22 wt.%, while the S content remains approximately

constant (5.4–5.8 wt.%). Arsenic is also accumulated in jarosite-beudantite solid solutions (up to 8.4 wt.% As), which

occur as inclusions in the amorphous Fe-sulfoarsenates. In efflorescent crusts on the surface of the waste pile, As co-

precipitates with the Fe(III) sulfates copiapite (0.27 wt.% As) and rhomboclase (0.87 wt.% As). Zinc and Cu are

incorporated primarily into Fe(II) sulfates, i.e. melanterite in the interior of the waste pile, and rozenite in the efflor-

escent crust. The Zn mineral dietrichite is also formed at the surface of the waste pile as a result of evaporation of pore

solutions, and is the only Fe(II) sulfate containing detectable amounts of As (0.64 wt.%). Lead is mainly co-pre-

cipitated with minerals of the jarosite group, where the Pb content may reach 4.3 wt.%. Co-precipitation of toxic ele-

ments with sulfates and sulfoarsenates of Fe is shown to be a significant mechanism in controlling the concentration of

heavy metals in pore solutions of high-sulfide mine wastes. Precipitation of secondary phases causes the formation of a

hardpan layer with low permeability at a depth of 1–1.5 m below the surface of the waste pile. Rainwater accumulates

above the hardpan horizons and slowly drains along these aquicludes to the bottom of the pile. Most of the rainwater

evaporates during infiltration. This leads to formation of the described efflorescent sulfate crusts. Dissolution of these

crusts during the next rain storm produces highly acidic surface waters (pH=1.1) rich in SO42 (30 g/l), Fe (18 g/l), As

(0.24 g/l), Zn (0.12 g/l), Cu (0.04 g/l), Pb and Cd (0.002 g/l). During the warm (t>0 C) period of the year, which lasts

about 7 months, these surface waters transport a total of a few tens of kilograms of As and Zn, several kilograms of Cu, and a few hundred grams of Pb and Cd from the waste pile into the Mokry Berikul river. As a result, the con-

centrations of these metals in the river water increase by an order of magnitude, thus reaching levels close to, or

exceeding the maximum values permissible for drinking water.

# 2003 Elsevier Science Ltd. All rights reserved.

0883-2927/03/$ - see front matter # 2003 Elsevier Science Ltd. All rights reserved.

doi:10.1016/S0883-2927(03)00055-6

Applied Geochemistry 18 (2003) 1347–1359

www.elsevier.com/locate/apgeochem

* Corresponding author.

E-mail address: [email protected] (R. Giere ´ ).

mailto:[email protected]:[email protected]://www.sciencedirect.com/http://www.sciencedirect.com/http://www.sciencedirect.com/


2/13

1. Introduction

Abandoned mine wastes containing high sulfide con-

centrations are among the most serious sources of

environmental pollution. Understanding the geochem-

ical processes which control precipitation and dissolu-

tion of secondary minerals in abandoned sulfide mines iscrucial for the formulation of models that predict the

environmental impact of such sites. Moreover, a better

knowledge of these mechanisms will allow remediation

of existing problem sites and/or a reduction of the

extent of future pollution. Pore waters in and drainage

solutions from high-sulfide waste are characterized by

low pH values and high concentrations of various heavy

metals (Blowes et al., 1991; Nordstrom, 1991). The

concentration of heavy metals in the pore solutions is

mainly controlled by their precipitation together with Fe

hydroxides and/or sulfates (Blowes and Jambor, 1990).

Precipitation and dissolution cycles of some secondaryminerals are strongly influenced by seasonal wetting and

drying cycles (Frau, 2000), and thus it is important to

include meteorological parameters in models that simu-

late environmental impacts. Although mobilization of

As from mine waste is discussed in the literature, most

reports focus on low-sulfide wastes only (e.g., Al et al.,

1994; Leblanc et al., 1996; Roussel et al., 1998; Lang-

muir et al., 1999; Shuvaeva et al., 2000; Ardau et al.,

2001; Gaskova and Bortnikova, 2001).

The goal of the present study is to understand the

processes controlling the migration and sequestration of

Cu, Zn, and Pb and, in particular, the mobility of As in

high-sulfide waste piles. To achieve this goal, the authors

investigated high-sulfide mine wastes at the Berikul Au

mine in Siberia. A specific objective of the present paper

is to combine detailed mineralogical investigations of

the secondary phases occurring in the waste with both

meteorological observations and studies of the water

chemistry of samples collected in various parts of the

waste pile and in the nearby river.

2. Description of the waste site

The Berikul Au mine is situated in the northern partof the Kemerovo region, Western Siberia, about 450 km

NE of Novosibirsk (Fig. 1). The deposit, an Au-sulfide-

quartz vein with a Au content of 1–5 g/t, was mined

exclusively for Au. The mine was in operation between

1942 and 1991, but no other production data were

available to the authors. Gold occurred as fine-grained

intergrowths with sulfide minerals, mainly pyrite and

arsenopyrite. From these sulfides, Au was extracted at

the Berikul mill by using the cyanide technique. After

removal of the Au-bearing cyanide solutions, the sulfide

flotation residues were neutralized by adding Ca(ClO)2

before being dumped on waste piles. The waste studiedhere has been in a pile since 1952, while waste from

other piles was used for road construction when new

tailings impoundments were built in 1972.

The discarded material contains 40–45 wt.% fine-

grained sulfides, including pyrite (35–40 wt.%), arseno-

pyrite (2–5 wt.%), and minor amounts of pyrrhotite,

sphalerite, chalcopyrite, and galena. Among the gangue

minerals found in the wastes, the predominant phases

are quartz (30–35 wt.%), albite (5–10 wt.%), chlorite

(5–10 wt.%), muscovite (about 5 wt.%), and calcite (3–5

wt.%). The studied high-sulfide wastes have been

deposited on alluvial material, consisting of carbonate

boulders, and were stored for about 50 a on the left

bank of the Mokry Berikul river. The waste pile has a

length of approximately 250 m, a width of 50 m at its

base, and a height of 3 m (Fig. 2). The alluvial material

around the waste pile is dry, and no springs have been

detected near the river bank, suggesting that the river

Fig. 1. Map showing the location of the Berikul Au mine in the Kemerovo region of Southwestern Siberia.

1348 R. Gieré et al. / Applied Geochemistry 18 (2003) 1347–1359


3/13

represents the local ground water table. The only

‘‘springs’’ found are drainage water emanations at the

base of the waste piles (Plate IA, Fig. 2).

The Berikul site is located at an altitude of 850 m

above sea level. The average yearly temperature is

1.5 C, and the total precipitation averages 600 mm of

rain and snow annually. There is, however, a distinct

warm period during which the temperature is above

freezing. This warm period lasts from May to October,

and most of the precipitation (approximately 400 mm)falls during this time.

3. Methods of investigation

Solid samples were collected from both surface out-

crops and excavation pits, which were dug with a

mechanical excavator in different parts of the waste pile

(see Fig. 2). The pits were excavated in order to gain an

insight into the stratification of the waste pile, to com-

pare vertical and lateral zoning, and to collect samples

from the interior of the pile. The solids were then put

into hermetically sealed polyethylene bags and frozen

immediately to preserve the initial characteristics of

pore waters. The solid waste material was studied by

reflected light microscopy and scanning electron micro-

scopy (Jeol JSM-36). X-ray powder diffraction (XRD)

analyses were performed with a DRON-UM dif-

fractometer (Burevestnik, made in Russia) using filtered

Cu-K a radiation. Thermogravimetric analysis (TGA)

was carried out with a MOM device (made in Hungary),

using a 120 mg sample, which was heated from roomtemperature to 1000 C, at 12 C/min.

The compositions of the secondary phases were

determined with a CAMECA-SX50 electron microp-

robe at the Department of Earth and Atmospheric Sci-

ences of Purdue University. The instrument is equipped

with 4 wavelength dispersive spectrometers, and was

operated for quantitative analysis at an acceleration

potential of 20 kV and a beam current of 80 nA mea-

sured on a Faraday cup. Samples and standards were

coated with 20 nm of C. Well-characterized minerals

and synthetic oxides were used as standards. Data col-

lection time was 20 s for most major elements, and

Fig. 2. Schematic map of the studied waste pile and the surrounding area at the Berikul site showing sample localities, hydrologicalstations, and excavation pits.

R. Gieré et al. / Applied Geochemistry 18 (2003) 1347–1359 1349


4/13


5/13

thawed in the laboratory. With the exception of the pore

solutions, the Eh and the pH of all water samples were

measured in the field immediately after sampling by

using an INFRASPAK potentiometer (made in Russia),

whereby the precision of a single measurement was 10

mV for Eh, and 0.08 for pH. The Eh and pH mea-

surements for the pore solutions were carried out onlyafter the samples had been thawed and the solutions

extracted in the laboratory. Approximately 100 ml of

solution were collected by a syringe through a filter

(0.45 mm) into glassware, and were subsequently divided

into two aliquots. One of the aliquots was then acidified

with HNO3 to preserve the metal concentration,

whereas the other aliquot was preserved in its initial

state. All water samples were stored about 1 month at a

temperature 4–6 C in a refrigerator. The concentrations

in the acidified solutions of As, Ca, Cd, Cu, Fe, K, Mg,

Na, Pb, and Zn were determined by flame atomic-

absorption spectrometry (AAS; Perkin-Elmer equip-ment, model 3030E equipped with an HGA-600

graphite furnace) and by thermal-electric AAS (Pue-

Unikam equipment, model SP-9). The contents of

NH4+, Cl, F, NO3

, HCO3, and SO4

2 were deter-

mined in the second aliquot by ion chromatography

using a Russian-made MILIXROM chromatograph.

4. Results and discussion

4.1. The waste pile in cross-section

During the fifty 50 a of storage in the pile, the waste

was subjected to supergene alteration, which led to a

characteristic layering. In cross-section, 5 main hor-izons can be distinguished in the waste pile (Fig. 3).

These are distinct in terms of mineral content, color,

porosity and hardness, and comprise, from bottom to

top:

4.1.1. Horizon 1

This zone consists of friable, only slightly altered sul-

fide wastes of gray-green color. It contains 3–5 wt.%

calcite, and is approximately 1–1.5 m thick.

4.1.2. Horizon 2

Overlying horizon 1, this layer consists of lithifiedwaste containing gypsum as binding material. It is a

hardpan layer with a thickness of approximately 1 m.

Leaching cavities are observed in this zone (shown in

black in Fig. 3), and these are often filled by jarosite and

amorphous Fe-sulfoarsenates (Plate IB). As a rule, such

hardpan layers are characterized by low permeability,

which prevents penetration of solutions and gases into

the deeper horizons of waste piles (Blowes et al., 1991).

At the studied site, the hardpan layer contains trace

amounts of calcite, i.e. approximately 1 wt.%, but all

overlying horizons are devoid of calcite.

4.1.3. Horizon 3

Overlying the hardpan layer is a tobacco-colored,

0.5–1 m thick horizon, which consists of very moist and

fine-grained wastes of silt size. This zone, referred to as

the melanterite zone, contains leached relics of hardpan

material (Fig. 3), which are overgrown by melanterite

aggregates (up to 10 cm across). The presence of such

relics of lithified material in horizons above the actual

hardpan layer documents that the lithified waste is dis-

solving as a result of decreasing pH in the pore solutions

during sulfide weathering. The hardpan material,

however, decomposes only slowly, because of its low

permeability.

4.1.4. Horizon 4

This thin intermediate zone has a gray color, and is

composed of quartz, jarosite and sulfides. It separates

the melanterite zone from the overlying horizon 5.

4.1.5. Horizon 5

The uppermost horizon is distinctly yellow, is up to

0.5 m thick, and contains some strongly oxidized relics

of hardpan material. The predominant phase is jarosite;

hence, this horizon is referred to below as the jarosite

zone.

Fig. 3. Supergene weathering profile through the waste pile at

the Berikul site. This profile displays the situation encountered

in excavation pit B-2/99 in the eastern part of the waste pile (see

Fig. 2), but it is representative of the entire site. The numbered

horizons are described in the text.



6/13

4.2. Secondary minerals

4.2.1. Gypsum (CaSO42H 2O)

Gypsum is the earliest secondary mineral found, and

it occurs even in the slightly altered sulfide wastes of

zone 1. In the hardpan layer, gypsum crystals are up to

2 mm across and form a framework that binds the fine-grained sulfide phases (Plate IB). The concentrations of

As, Cu, Zn, and Pb in gypsum are all below detection

limits.

4.2.2. Jarosite solid solutions

Two main varieties of jarosite-group phases were

detected, and these can be distinguished on the basis of

the predominance of alkali-site ions (Table 1). The first

variety is hydronium jarosite (H3O,K,Na)Fe3+3 (-

SO4)2(OH)6. The second variety is jarosite sensu stricto,

(K,H3O,Na)Fe3+3 (SO4)2(OH)6, with K concentrations

that are considerably higher (3.1 wt.%) than in hydro-nium jarosite. Average Na concentrations are low in

both varieties, namely 0.3 and 0.5 wt.% in hydronium

jarosite and jarosite, respectively. Hydronium jarosite

forms spherical aggregates up to 20 mm in size, which

were observed in all horizons (Plate IC). Extensive pre-

cipitation of hydronium jarosite must have started after

formation of gypsum in the hardpan layers, as docu-

mented by the mineralogical zoning observed around

leaching cavities in the hardpan (typical zoning shown

in Plate IB).

The zones more distant from the open cavity are less

altered and contain the earliest secondary phase, i.e.

gypsum (Zone 1 in Plate IB). In the more weathered

material, which forms the walls of cavities (Zone 2 in

Plate IB), hydronium jarosite begins to appear. Sul-

foarsenates are observed closest to and as incrustations

of the cavities (Zone 3 in Plate IB). From these obser-

vations, it is concluded that during the weathering of the

waste material, the secondary minerals crystallized in

the following sequence: gypsum ! hydronium jarosite

! sulfoarsenates.

The second jarosite variety, jarosite sensu stricto,

occurs as oolites of about 5 mm in diameter along cracks

(Plate IC) in horizon 4 (see Fig. 3). It also forms rims

around hydronium jarosite, showing clearly that it pre-

cipitated after hydronium jarosite. Jarosite is con-

siderably richer in Cu and Zn than hydronium jarosite

(Table 1). Moreover, jarosite is characterized by sig-nificantly higher contents of both As (1.7 wt.%) and Pb

(4.3 wt.%). Joint incorporation of As and Pb into jar-

osite is consistent with the possible occurrence of a solid

solution between jarosite [KFe33+(SO4)2(OH)6] and

beudantite [PbFe33+(AsO4,SO4)(OH)6; see also Jambor

and Dutrizac, 1983; Rattray et al., 1996].

4.2.3. Amorphous iron sulfoarsenates (AISA)

Sulfoarsenates of Fe are precipitated in the leaching

cavities observed in the hardpan layer (Plate IB), as well

as in the lithified hardpan relics in the waste of the

overlying horizons 3 and 5 (Fig. 3). These phases are X-ray amorphous, and exhibit a reddish-brown to reddish-

orange color. As outlined below, there are 3 varieties of

AISA, which can be distinguished on the basis of their

chemical composition. Since the authors were unable to

select enough material of a specific type of AISA based

on its physical appearance, a sample of non-distinct

AISA had to be used for infrared (IR) spectroscopy,

TGA and XRD. The IR spectrum of this material is

similar to that of sarmientite, Fe3+2 (AsO4)(-

SO4)OH5H2O, and thus qualitatively points to a simi-

lar composition (Fig. 4a). The thermal properties of

these two phases are also similar, as documented by the

weight loss curves shown in Fig. 4b. The weight loss

between 100 and 685 C, representing water content, is

30.2% for the amorphous phase, and 23.0% for sar-

mientite. The weight losses between 685 and 980 C,

representing the SO3 content, are 4.8 and 16.4% for the

amorphous phase and sarmientite, respectively. To

explore which phases would crystallize from the amor-

phous substance if it were heated, the AISA sample was

heated to 220 C and kept at that temperature for 6 h.

Table 1

Average elemental concentrations (with standard deviations) in sulfoarsenates and sulfates of Fe (wt.%), as determined by electronprobe microanalysis

n Al As Cu Fe K Pb S Zn

Hydronium jarosite from horizon 4 7 0.110.07 0.730.10 0.010.01 28.81.3 0.970.26 0.310.08 11.80.3 0.010.02

Hydronium jarosite from horizon 5 24 0.120.08 0.350.13 0.030.02 27.22.3 1.60.3 0.360.24 10.80.7 0.020.02

Jarosite from horizon 4 7 0.060.02 1.70.2 0.240.08 29.90.6 3.10.4 4.30.8 12.50.3 0.170.09

AISA, matrix of group I 12 0.300.11 11.01.0 0.040.03 34.31.4 0.070.08 0.070.03 5.40.7 0.080.05

AISA, matrix of group II 33 1.20.3 14.01.3 0.030.03 28.81.0 0.020.03 0.090.05 5.90.4 0.260.10

AISA, group III 82 1.90.4 21.61.4 0.090.04 20.91.7 0.030.10 0.890.35 5.51.0 0.290.07

Inclusions in matrix of group I 6 0.200.10 8.12.3 0.040.03 32.01.1 1.00.5 0.340.26 7.81.4 0.060.04

Inclusions in matrix of group II 16 2.90.9 8.42.5 0.030.03 25.22.6 1.81.5 1.71.1 8.01.2 0.240.10

n=Number of analyses; AISA is amorphous Fe-sulfoarsenates.



7/13

Following heat treatment, an XRD pattern was gener-

ated, revealing peaks that correspond to the d-spacings

of the strongest lines of jarosite, beudantite, and goe-

thite (Fig. 4c). The crystalline equivalent of the studied

AISA sample, thus, is a phase mixture, which displays

an overall similarity in IR and thermal properties to the

Fe-sulfoarsenate sarmientite. This crystalline phase

mixture, however, does not correspond exactly to the

amorphous starting material, because the heat treatment

must also have changed the water content (see Fig. 4b).

Among the amorphous Fe-sulfoarsenates, up to 3

types may be distinguished by chemical composition

and microstructure. The two earliest varieties, adjoining

the walls of the cavities, are reddish-brown in color and

consist of a matrix containing microscopic spherical

inclusions (Plate ID), which will be discussed below.

Farthest away from the cavity walls, a third zone occurs

which is reddish-orange in color, and does not contain

any inclusions. The As content in the matrix increases

from the earliest variety (AISA, group I, Table 1) to the

Fig. 4. Properties of an amorphous Fe-sulfoarsenate sample. (a) Infrared (IR) absorption spectra showing the absorption bands cor-

responding to molecules of water, sulfate and arsenate. Solid line=spectrum for amorphous Fe-sulfoarsenate (this study); dotted

line=spectrum for sarmientite (from Abeledo and Benyacar, 1968.); (b) thermogravimetric data for amorphous Fe sulfoarsenate

(solid line) and sarmientite (dotted line); (c) powder XRD pattern obtained after heating the amorphous Fe-sulfoarsenate material.The pattern reveals a mixture of beudantite (Bd), jarosite (Jr) and goethite (Gt).



8/13

latest one (group III) from 11 to 22 wt.%, while the Fe

content decreases in the same order, from 34 to 21

wt.%. The heavy metal contents increase to a lesser

extent, namely Zn from 0.08 to 0.29 wt.%, Cu from 0.04

to 0.09 wt.%, and Pb from 0.07 to 0.9 wt.%. This che-

mical evolution from group I to group III takes place at

nearly constant S contents (Table 1). In the ternary dia-

gram shown in Fig. 5, the matrix of group II plots close

to the ideal composition of beudantite (PbFe3+3 (AsO4,-

SO4)(OH)6), i.e., it is significantly richer in Fe than

stoichiometric bukovskyite (Fe3+2 (AsO4)(-

SO4)OH7H2O) and sarmientite. Bukovskyite and beu-

dantite have been identified at the Carnoules Pb-(Zn)

mine, Gard, France where they are associated withscorodite (Fe3+AsO42H2O) and angelellite

(Fe3+4 As2O11), which were precipitated from acidic mine

waters (Leblanc et al., 1996). Group-III AISA plot near

the ideal composition of zykaite (Fe3+4 (AsO4)3(-

SO4)OH15H2O) in Fig. 5, but they are richer in SO3.

As displayed in Fig. 5, the studied amorphous sulfoar-

senates exhibit a wide compositional variation, and their

average compositions do not correspond to the stochio-

metry of the discussed minerals. The inclusions in group

I and II contain more Al, K, Pb and less As in compar-

ison to the matrix (Plate ID, Table 1). On the ternary

As2

O5 –SO

3 –Fe

2O3

diagram, the compositions of these

inclusions form distinct trends between jarosite and

beudantite, suggesting that they represent solid solu-

tions between these two phases.

In summary, the chemical analyses and the X-ray

powder pattern of the heated amorphous substance

indicate that the inclusions may represent poorly crys-

tallized jarosite (KFe33+(SO4)2(OH)6)–beudantite

(PbFe33+(AsO4,SO4)(OH)6) solid solutions. The average

contents of SO3 and As2O5 in jarosite–beudantite are

similar in both group I and group II inclusions, but the

group I inclusions are richer in Fe (Table 1, Fig. 5).

Additionally, the second group is characterized by

higher concentrations of Al and Zn. The latter is sub-

stituting for Fe in the jarosite structure. The overallsequential increase in Al, As, Zn and Pb observed for

both the matrix and the jarosite - beudantite inclusions

from earliest to latest varieties suggests that the con-

centrations of these elements in the pore solution

increased during formation of these phases. Such an

increase in concentration in solutions with simultaneous

deposition of solids is possible only if water evaporates.

4.2.4. Melanterite (Fe2+SO47H 2O)

Melanterite occurs as green crystals (up to 2 cm

across) in the interior parts of the waste pile. This is in

contrast to other soluble Fe-sulfates, which have been

Fig. 5. Ternary diagram (in mol%) for the system As2O5 –SO3 –Fe2O3 –H2O, showing the ideal composition (star symbols) of selected

minerals in the system, and the analyzed compositions of jarosites and amorphous Fe-sulfoarsenates (AISA) from the Berikul site.



9/13

found only on the surface of the waste pile. Melanterite

is observed to overgrow hardpan relics, which contain

jarosite solid solutions and amorphous Fe-sulfoarse-

nates, and therefore is clearly younger than both the

jarosite solid solutions and the amorphous Fe-sulfoar-

senates. In the uppermost portions of the waste pile,

however, melanterite gives way to jarosite (horizons 4and 5, Fig. 3), probably as a result of the more oxidiz-

ing conditions near the surface of the waste pile. Thus,

sulfates and sulfoarsenates of Fe3+ are precipitated

during the earliest and last stages of weathering,

whereas sulfates of Fe2+ (i.e. melanterite) are formed

during the intermediate stage. This unusual develop-

ment of the weathering process, is at present not

understood.

Melanterite contains considerable amounts of Zn and

Cu (Table 2). Pisanites, i.e. Cu–Zn varieties of mel-

anterite, are common in wastes of sulfide ore deposits in

the Ural region (Emlin, 1991), and Zn-bearing mel-

anterite has been reported from Iron Mountain, Cali-

fornia, USA (Alpers et al., 1994). Recently, melanterite

has also been described as an environmentally impor-

tant secondary phase formed as a result of pyrite oxi-

dation at an abandoned mine in Sardinia, Italy (Frau,

2000).

4.2.5. Iron sulfates in efflorescent crust

On the slopes of the waste pile, efflorescent crusts

consisting of Fe-sulfates were observed. In these crusts,

formed through evaporation of pore solutions, the fol-

lowing Fe-sulfates were identified: rozenite (Fe2+

SO44H2O), copiapite (Fe2+Fe43+

(SO4)6(OH)220H2O),and rhomboclase (HFe3+(SO4)24H2O). The efflor-

escent crusts further contain the Zn mineral dietrichite,

(Zn,Fe2+)Al2(SO4)422H2O, which was also identified

by powder XRD and which contains equal amounts of

Zn and Fe (3.3 wt.%). The Fe2+/Fe3+ ratio decreases

from rozenite to copiapite, to rhomboclase (see the for-

mulae above), in parallel to the decrease in the contents

of Zn and Cu (Table 2). At the Berikul site, thus, Fe2+-

sulfates seem to be richer in Cu and Zn than Fe3+-sul-

fates. On the other hand, the highest As content is

observed in rhomboclase, suggesting that As is captured

when Fe(III) sulfates precipitate.

4.3. Water characteristics

During this study, 4 types of water were distinguished on

the basis of their occurrence: pore waters, drainage (infil-

trating) waters, surface waters, and water of the Mokry

Berikul river. Each type of water is a link in the pathway of

element migration into the environment (Fig. 6).The pore solutions are generated through interaction

of sulfides, rainwater and atmospheric O2. They are

accumulated above the low-permeable hardpan layer,

mainly in the melanterite zone (horizon 3, Fig. 3). It is

assumed that only a small part of the solutions could

penetrate through the hardpan layer, because the

slightly altered wastes in horizon 1 remained dry even

Table 2

Average elemental concentrations (with standard deviations) of As, Zn, Cu and Pb in the soluble sulfate phases (wt.%)

n As Zn Cu Pb

Melanterite, Fe2+SO47H2O 3


10/13


11/13

that dissolution of surface minerals was much more

pronounced during the first rain storm, probably

because the intermittent dry period between the storms

was too short to build up a significant amount of sec-

ondary surface minerals in the efflorescent crusts. Tak-

ing the average metal concentrations in the surfacewaters (listed in Table 3) and the average discharge

volume for these two events (480 l), it was calculated

that each storm removed, on average, approximately

113 g As, 57 g Zn, 19 g Cu, 0.8 g Pb, and 0.8 g Cd from

the slope of the waste pile facing the Mokry Berikul

river, and discharged the metals into the river.

According to these measurements, and based on aver-

age meteorological data (400 mm of rain during the

warm season), it has been calculated that during the

warm season, a few tens of kilograms of As and Zn, sev-

eral kilograms of Cu, and a few hundred grams of Pb and

Cd might be transported into the Mokry Berikul river.

Some of the dissolved metals will be transformed into

suspended solid precipitates as soon as the acid surface

streams mix with the nearly neutral river water. The

above calculation assumes that the rainstorms whichwere sampled are typical of other rainstorms during the

warm season, and thus the authors are unable to antici-

pate the effects of much heavier or much lighter rains.

The river water exhibits a pH that ranges from 7.6

(upstream, sample B-4) to 6.5 (downstream, sample

B-11), reflecting the input of acid water from the waste

pile (Table 5). The river water samples have an average

Eh of +370 mV, and their total salt content is approxi-

mately 120 mg/l (Table 5). This water is a SO42-enriched

(12.5 mg/l on average) HCO32 –Ca type, with average

Table 4

Results of individual meteorological, chemical and hydrological measurements during two consecutive rainstorms in August 2000:

precipitation, elemental concentrations in surface waters (in mg/l), and volume of surface water (in l) discharged into the river for each

measuring station (see Fig. 2)

Precipitation Sampling station Zn Cd Pb Cu As Volume

1.93 mm (20.08.2000) ST-1/1 200 2.6 1.9 52 300 446ST-1/2 160 2.6 1.6 47 280 500

1.96 mm (22.08.2000) ST-2/1 55 0.7 1.7 26 170 423

ST-2/2 60 0.8 1.7 30 190 551

The data shown in Table 3 for the surface waters represent the average of all 4 measurements listed here.

Table 5

Water analyses of samples collected from the Mokry Berikul River (see Fig. 2). B-4: upstream; B-10: near waste pile; B-11: down-

stream

Sample # B-4 B-10 B-11 MCL (US) MCL (Russia)

pH 7.6 7.1 6.5 – –

Eh (mV) 389 359 346 – –

As


12/13

contents of 18 mg/l Ca and 82.5 mg/l HCO32. Compared

to the upstream river water (sample B-4), the concentra-

tions of As, Cu, Zn, Pb and Cd are significantly higher in

the water near the waste pile (sample B-10), and gen-

erally even higher further downstream (sample B-11).

For example, the downstream concentration of Cd is

higher by two orders of magnitude than the upstreamconcentration. The concentration of As in the river near

the waste pile (sample B-10) is much higher than that in

the upstream water, and specifically, it is one order of

magnitude higher than the maximum contaminant level

allowed in drinking water in the US (EPA, 2001). A

similar observation can be made for the downstream

concentration of Cd. For Zn, the concentrations are

close to the maximum concentrations permitted in

drinking water in Russia (Eremeev, 1990).

The data clearly document that the waters emanating

from and running off the waste pile have a serious impact

on the water quality of the Mokry Berikul river. Thisenvironmental impact is particularly dramatic during the

warm season, when most of the precipitation is recorded

and evaporation is most intense. During the major part

of the cold season, the waste pile is covered by snow, which

reduces the evaporation as well as the amount of runoff.

5. Conclusions

Acid solutions containing high concentrations of

SO42, Fe, As and heavy metals are generated during

sulfide oxidation in the Berikul waste pile. The mobility

of As, Cu, Zn and Pb within the waste pile is controlled

by precipitation of these metals as secondary phases.

Arsenic is precipitated in the form of amorphous Fe-

sulfoarsenates, which form a matrix with inclusions of

jarosite–beudantite. These inclusions show lower con-

centrations of As than the matrix. On the surface of the

waste pile, As co-precipitates with sulfates containing

trivalent Fe. Copper and Zn are precipitated together

with melanterite and rozenite, because these metals sub-

stitute for Fe2+ in sulfates. Within the efflorescent crusts,

Zn is accumulated in dietrichite. Most of the Pb is cap-

tured by jarosite–beudantite solid solutions. A sequential

increase in Al, As, Zn and Pb in both amorphous sulfoar-senates and jarosite–beudantite inclusions suggests that

the concentrations of these elements increase in the pore

solution when the solid phases precipitate, a feature that

can be explained by slow water evaporation.

This study has established that the main pathway of

element migration is via surface drainage during and

after rainstorms. In dissolved form, a few tens of kilo-

grams of As and Zn, several kilograms of Cu, and sub-

kilogram quantities of Pb and Cd are removed by sur-

face waters and transported into the Mokry Berikul

river during the warm season of the year. This discharge

results in a dramatic increase in the As, Cu, Zn, Pb and

Cd concentration in the river water, where some of these

metals reach concentrations near or in excess of the

maximum levels permitted for safe drinking water.

Acknowledgements

The authors are grateful to Dr. Richard Wanty, Dr.

Pierfranco Lattanzi, and an anonymous reviewer for

providing constructive reviews. Their valuable sugges-

tions and thoughtful criticism of an earlier version

helped us to improve the quality of this paper. We fur-

ther would like to thank Carl Hager for his assistance at

the Purdue University electron microprobe.

References

Abeledo, M.E.J., Benyacar, M.A.R., 1968. New data on sar-

mientite. Am. Mineral. 53, 2077–2082.

Al, T.A., Blowes, D.W., Jambor, J.L., 1994. A geochemical

study of the main tailings impoundment at the Falconbrige

Limited, Kidd Creek Division Metalurgical Site, Timmins,

Ontario. In: Jambor, J.L., Blowes, D.W. (Eds.), Short

Course Handbook on Environmental Geochemistry of Sul-

fide Mine Waste. Mineral. Assoc. Can, Waterloo, pp. 59–

102.

Alpers, C.N., Nordstrom, D.K., Jambor, J.L., 1994. Secondary

minerals and acid mine-water chemistry. In: Jambor, J.L.,

Blowes, D.W. (Eds.), Short Course Handbook on Environ-

mental Geochemistry of Sulfide Mine Waste. Mineral. Assoc.

Can, Waterloo, pp. 247–270.Ardau, C., Frau, F., Dadea, C., Mattusch, J., Wennerich, R.,

Titze K., 2001. Solid- state of arsenic in waste materials and

stream sediments from abandoned mine area of Baccu Locci

(Sardinia, Italy). In: Proc. Int. Conf. WRI - 10. Villasimius,

Italy, pp. 1173–1176.

Ball, J.W., Nordstrom, D.K., Zachmann, D.W., 1987.

WATEQ4F—a personal computer FORTRAN translation

of the geochemical model WATEQ2 with revised data base:

US Geol. Surv. Open-File Rep. 87-50.

Blowes, D.W., Jambor, J.L., 1990. The pore-water geochem-

istry and the mineralogy of the vadose zone of sulfide tail-

ings, Waite Amulet, Quebec, Canada. Appl. Geochem. 5,

327–346.

Blowes, D.W., Reardon, E.J., Jambor, J.L., Cherry, J.A., 1991.The formation and potential importance of cemented layers

in inactive sulfide mine tailings. Geochim. Cosmochim. Acta

55, 965–978.

Emlin, E.F., 1991. Technogenesis of pyrite deposits of Ural.

Publication of Ural State University Sverdlovsk (in Russian).

EPA, 2001. United States Environmental Protection Agency,

Office of Water. Available from: www.epa.gov/safewater.

Eremeev, A.N. (Ed.), 1990. Handbook of Geochemical

Exploration of Mineral Resources. Nedra, Moscow.

Frau, F., 2000. The formation-dissolution-precipitation cycle of

melanterite at the abandoned pyrite mine of Genna Luas in

Sardinia, Italy: environmental implications. Mineral. Mag.

64, 995–1006.


http://-/?-http://-/?-


13/13

Gaskova, O.L., Bortnikova E.P., 2001. Experimental modeling

of trace element leaching from As-bearing tailings impound-

ments. In: Proc. Int. Conf. WRI - 10. Villasimius, Italy, pp.

1233–1236.

Jambor, J.L., Dutrizac, J.E., 1983. Beaverite – plumbojarosite

solid solutions. Can. Mineral. 21, 101–113.

Kolmogorov, Y., Trounova, V., 2002. Analytical potential of

EDXRF using toroidal focusing systems of highly oriented

pyrolytic graphite (HOPG). X-ray Spectrom. 31, 432–436.

Langmuir, D., Mahoney, J., MacDonald, A., Rowson, J., 1999.

Predicting arsenic concentrations in the pore waters of buried

uranium mill tailings. Geochim. Cosmochim. Acta 63, 3379–

3394.

Leblanc, M., Achard, B., Ben Othman, D., Bertrand-Sarfati, J.,

Personne ´ , J.Ch., 1996. Accumulation of arsenic from mine

waters by ferruginous bacterial accretions (stromatolites).

Appl. Geochem. 11, 541–554.

Nordstrom, D.K., 1991. Chemical modeling of acid mine

waters in the Western United States. Meeting Proc. USGS

Water Resour. Invest. Rep. # 91-4034, pp. 534–538.

Pouchou, J.L., Pichoir, F., 1984. Un nouveau mode ` le de calcul

pour la microanalyse quantitative par spectrome ´ trie de

rayons X. Partie I: application a ` l’analyse d’e ´ chantillons

homoge ` nes. Recherches Ae ´ rospatiales 3, 167–192.

Rattray, K.J., Taylor, M.R., Bevan, D.J.M., Pring, A., 1996.

Compositional segregation and solid solution in the lead-

dominant alunite-type minerals from Broken Hill, N.S.W.

Mineral. Mag. 60, 779–785.

Roussel, Ch., Bril, H., Fernandez, A., 1998. Hydrogeochemical

survey and mobility of As and heavy metals on the site of a

former gold mine (Saint-Yrieix mining district, France).

Hydroge ´ ologie 1, 3–12.

Shuvaeva, O.V., Bortnikova, S.B., Korda, T.M., Lazareva,

E.V., 2000. Arsenic speciation in a contaminated gold pro-

cessing tailings dam. Geostand. Newslett. 24, 247–252.

Sidenko, N., 2001. Arsenic and Heavy Metal Migration in

Weathering Zone of Berikul Sulfide Waste. PhD thesis,

Institute of Geology SB RAS. Novosibirsk, Russia (in

Russian).


Documents

The Role of Secondary Minerals in Controlling