assessment and regulation of the ecological state of soils in the impact zone of mining and...

648

ISSN 1064-2293, Eurasian Soil Science, 2008, Vol. 41, No. 6, pp. 648–659. © Pleiades Publishing, Ltd., 2008.Original Russian Text © A.S. Yakovlev, I.O. Plekhanova, S.V. Kudryashov, R.A. Aimaletdinov, 2008, published in Pochvovedenie, 2008, No. 6, pp. 737–750.

INTRODUCTION

The study of technogenic impacts on the soil coverinvolves the problem of ecological rating of techno-genic loads on the environment with due account forthe natural conditions of particular regions and theireconomic significance [2, 5, 6, 10, 12, 25, 28]. Thechoice of appropriate parameters of the environmentalimpact assessment is the key problem [21]. Relativelywell-developed sanitary-hygienic principles and stan-dards predominate in the system of ecological stan-dardization [9]. In some cases, this approach is insuffi-cient, because it does not take into account the func-tional role of particular territories and the specificity oftheir environmental conditions [27, 28].

In the practice of environmental studies, it is impor-tant not only to assess the ecological state of soils butalso to determine permissible loads on them with dueaccount for different tolerances of soils with differentphysicochemical properties to the technogenic loads;the character of the land use should also be taken intoaccount [19, 28].

The specific natural-climatic conditions of soilfunctioning in the tundra zone, where plants of the min-ing and metallurgical company (MMC) Norilsk Nickelare found, and the presence of permafrost sharplydecrease the period of active water migration of mineraland organomineral compounds of heavy metals (HMs).Additionally, gleyzation favors the transformation of

some elements into lower oxide forms, which more eas-ily form soluble compounds. The redistribution of pol-lutants between the transeluvial (on slopes) and accu-mulative landscapes is well pronounced. Thus, it isimportant to determine the most informative parame-ters of the soil state in northern regions with dueaccount for their specific climatic features [14]; theseparameters should serve as the basis for developing anappropriate system of the ecological assessment andrating of northern soils.

The environmental quality assessment and rating foradequate regulation of anthropogenic impacts on theenvironment is the central idea of the ecological doc-trine of the Russian Federation and of the Federal LawOn Environmental Protection (no. 7-FZ, from January10, 2002) [26]. The procedure of ecological rating is themost important measure to regulate ecologically soundnature management in Russian and foreign systems ofenvironmental quality control.

Ecological rating is considered, first of all, as a pro-cess of establishing the quantitative limits within whichthe quality characteristics of the rated natural objectmay vary. At present, the legislative and methodologi-cal bases for ecological rating are poorly developed;first of all, this concerns the conceptual apparatus forthis procedure. Several relevant definitions from theLaw On Environmental Protection [26] are givenbelow.

DEGRADATION, REHABILITATION, AND CONSERVATION OF SOILS

Assessment and Regulation of the Ecological State of Soilsin the Impact Zone of Mining and Metallurgical Enterprises

of Norilsk Nickel Company

A. S. Yakovlev, I. O. Plekhanova, S. V. Kudryashov, and R. A. Aimaletdinov

Faculty of Soil Science, Moscow State University, Leninskie gory, Moscow, 119991 RussiaE-mail: [email protected]

Received July 24, 2007; in final form, January 16, 2008

Abstract

—An assessment of the ecological state of soils has been performed in the area of mining and metal-lurgical enterprises of Norilsk Nickel Company with respect to the level of soil contamination by heavy metals,the state of the vegetation, and the biological activity of the soils. The territory within 4 km from Norilsk ischaracterized by high concentrations of heavy metals, the absence of trees, and the disturbance of the organicmatter mineralization. This zone corresponds to level 5 of the loss of environmental quality. At distances of4

−

16 km from the city, the state of the environment corresponds to level 4, and, at distances of 16–25 km, tolevel 3. In the latter zone, the soils are characterized by increased concentrations of acid-soluble and mobilemetal compounds, though the concentrations of water-soluble metal compounds do not exceed the maximumpermissible levels; the soil microbiological activity is normalized. The state of the environment at a distance of25 km from Norilsk is close to level 2. Soil contamination with heavy metals is accompanied by a rise in theportion of Cu, Ni, and Co compounds bound with amorphous iron oxides and hydroxides, as well as in the por-tion of their mobile forms.

DOI:

10.1134/S1064229308060100

EURASIAN SOIL SCIENCE

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ASSESSMENT AND REGULATION OF THE ECOLOGICAL STATE OF SOILS 649

Ecological rating is procedure for establishing stan-dards of the environmental quality and norms of per-missible environmental impacts in the course of eco-nomic and other activities.

Environmental quality is the state of the environ-ment characterized by the physical, chemical, biologi-cal, and other parameters and/or their integrity.

An environmental impact assessment implies theidentification, analysis, and registration of direct, indi-rect, and other consequences of the impact of plannedeconomic and other activities on the environment inorder to make a decision about the feasibility of theirrealization.

Currently, there is no legislative definition of anenvironmental impact zone. It has been suggested todefine it as a territory within which qualitative andquantitative changes in the environment take placeunder the impact of a given enterprise [28].

According to these definitions, an ecological ratingimplies two interrelated parts: (a) the assessment andrating of the environmental quality in the impact zoneand (b) the regulation (control) of the environmentalquality through maintenance of permissible loads (themaximum permissible atmospheric emission, waterdischarge, and waste disposal).

To assess the environmental quality and environ-mental impacts, a well-know five-grade scale is used.According to it, the undisturbed environment and min-imum impacts on it correspond to grade 1. A cata-strophic state of the environment and catastrophicimpacts on it correspond to grade 5 [7]. The range from1 to 2 characterizes the normal state of the environmentwhen the environmental quality loss is from 0 to 20%[4, 28]. Experimental data suggest that a catastrophicstate of the environment with irreversible changes in itsproperties takes place when the environmental qualityloss exceeds 40%. The interval from 20 to 40% corre-sponds to the zone of ecological risk [4].

Our work was aimed at assessing the ecologicalstate of soils in the impact zone of MMC NorilskNickel. The following particular tasks were solved: (1)to assess the ecological state of soil in the impact zoneof MMC Norilsk Nickel with the use of chemical andbiological parameters indicative of different levels ofthe environment degradation, (2) to determine the mostinformative parameters of the ecological state of soilsfor assessing the level of soil contamination with dueaccount for the regional soil and climatic features, and(3) to develop approaches for the ecological rating ofthe soil and environmental quality in the impact zone ofMMC Norilsk Nickel.

OBJECTS AND METHODS

The studied area is found in the northern part ofKrasnoyarsk region within the southern part of TaimyrPeninsula. The climate is characterized by severe win-ters with the mean January temperature being about

–

30°ë

and relatively warm summers with a mean Julytemperature of

10–13°ë

. According to the long-termrecords of the weather station in Norilsk, southeasternwinds predominate in the winter and northwesternwinds in the summer (Fig. 1). The taiga vegetation con-sists of larch, birch, willow, and alder trees; ledum,juniper, bog bilberry, and cowberry in the shrub layer;and grasses, sedges, horsetails, and mosses in theground cover. Lichens are found within the unpollutedbackground territories.

The soils are developed under conditions of shallowcontinuous permafrost and relatively weak moistureevaporation; gley processes are widespread. The cryo-genic mass exchange is active and results in the devel-opment of cryogenic microtopography. The soil coveris characterized by high heterogeneity. Tundra gleysoils predominate; there are also hydromorphic peatbog and alluvial soils [3]. Heavy loams of marine originand, rarely, light and medium loams are the major typesof parent materials within the Taimyr Lowland.

The anthropogenic impact on the local soils andvegetation is due to gaseous and dust emissions and dis-posal of wastes from plants of MMC Norilsk Nickel.Copper, nickel, cobalt, iron, manganese, and sulfurcompounds are the priority pollutants. We investigatedthe northeastern part of the region from the city ofNorilsk to the city of Talnakh; ore mining and process-ing enterprises, mines, and tailing dumps are found inthis area.

The soil sampling was performed in late July 2004.The sampling plots were selected with due account forthe type of landscapes and the character of the techno-genic loads (aerial pollution and leakages from tailingdumps). Overall, soils on 20 plots were investigated.They were arranged into the following groups: (1) soilsof sown lawns in Norilsk, (2) soils on the plots adjacentto the industrial zone and the tailing dumps, (3) soils ofthe plots at different distances from Norilsk (in thenortheastern direction), and (4) background soils at adistance of more than 100 km from the source of pollu-tion. We collected mixed samples from the surface soillayer (0–5 cm) and samples from the main genetic hori-zons.

The chemical properties of the soils controlling themigration of pollutants were studied: the pH; the totalacidity; the organic carbon content (by the Tyurinmethod with colorimetric ending); the ash content inthe litter and peat [1]; and concentrations of heavy met-als (Cu, Ni, Co, Mn, and Fe) in water, ammonium ace-tate (pH 4.8), and 1 N HNO

3

extracts [20]. The frac-tional composition of the HM compounds was studiedin sequential extracts from the same soil samples. Thefollowing HM fractions were determined: the water-soluble, exchangeable (with 0.1 M Ca

(

NO

3

)

2

), and spe-cifically adsorbed (with an ammonium acetate buffer,pH 4.8). The fraction of HMs bound with the soilorganic soil matter was extracted with an ammoniumacetate buffer (pH 4.8) after the organic matter destruc-

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Level 2, 25 km from Norilsk



2

1

3

å3

ç3

çå3

Level 5

Nadezhda

í‡ÎÌ‡ı

çÓË

Norilsk

1 2 3 4 5

tion with concentrated

ç

2

é

2

upon heating. The fractionof HMs bound with amorphous oxides and hydroxidesof iron was extracted by an oxalate buffer solution(pH 3.2) according to the Tamm procedure. The frac-tion of HMs bound with crystallized oxides andhydroxides of iron was also extracted with an oxalatebuffer solution upon the ultraviolet radiation of the soilsuspension. The concentrations of HMs in the residuewere calculated as the difference between the total con-tent of HMs and the sum of isolated fractions [21].

To assess the soil biological activity, the rates ofCO

2

emission from the soil during a particular intervalwere measured on a gas chromatograph [23].

RESULTS AND DISCUSSION

Most of the studied contaminated soils had a neutralor slightly alkaline (pH of water extract 6.0–7.5) reac-tion, whereas the reaction of background (unpolluted)soils was slightly acid. The effects of tailing dumps on

Fig. 1.

The scheme of the studied region and boundaries of the zones with different levels of environmental quality loss: (

1

) bound-aries of the zones, (

2

) slag dump, (

3

) dump of industrial waste, (

4

) tailing dumps 1 and 2, and (

5

) metallurgical plants.

1

3

2 M3


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the soil acidity were different. For example, soil alkal-ization was identified near tailing dump 1 created in the1970s; the soil pH exceeded the background values byabout 1.5 pH units. This was probably due to a consid-erable transformation of the pulp sludge in the dumpwith the development of reduction processes and wash-ing out of acid components during this time. The soilsnear tailing dumps 2 were more acid; their pH valueswere lower than the background ones (Table 1), whichwas obviously due to the leakage of acidic componentsof the sludge into the soil with snowmelt and rain water.The differentiation of the total acidity values was evenmore pronounced. The increase in the total acidityunder the impact of effluents from tailing dump 2 wasvery pronounced. The soils contaminated mostly fromthe aerotechnogenic source were characterized by aslightly alkaline reaction in places with excessivemoistening and by a slightly acid reaction in dryerplaces.

The thickness of the surface organic horizons of thesoils varied from 2–5 to 10–12 cm. Peat and raw-humushorizons representing a mixture of plant residues with dif-ferent degrees of decomposition predominated. Determi-nation of the humus content in the raw-humus horizonsinvolved significant difficulties related to the impossibilityof separation of root residues from the soil. The loss onignition was determined in such horizons; it reached30

−

60%. The humus content in the surface organic hori-zons varied from 2–5 to 10–12% depending on the pres-ence of the raw- humus organic matter. The accumulationof significant amounts of weakly decomposed organic res-idues in the soils was due to the predominance of theirconservation under the severe climatic conditions of thesouthern tundra and the suppression of cellulolytic micro-organisms in the soils heavily contaminated with heavymetals [17, 24, 30].

The regional background content of HMs in thesoils was determined in the area of the town ofDudinka, 100 km from the source of pollution. Thetotal contents of Cu, Ni, and Co in the surface horizonof the conventionally background soils comprised 28,29, and 15 mg/kg, respectively. As the natural variabil-ity in the contents of HMs in the surface soil horizonsis significant, the effect of pollution can be reliablyjudged if the concentration of heavy metals in the stud-ied soil exceeds the background value by 1.5–2 times[13].

Norilsk is an industrial center with three large met-allurgical plants. The urban soils of lawns in Norilskrepresent a mixture of slag and clinker with fertile soilmaterial or peat. The artificial lawns are found abovethe heating mains laid on the ground surface in ferro-concrete casings. Thus, the soils of these artificiallycreated lawns have a higher heat supply and are lesssubjected to waterlogging in comparison with the natu-ral soils. The soils of Norilsk are subjected to strongtechnogenic impact. The concentrations of HMs in thesoils of the lawns varied significantly, but all of themwere characterized by high and very high levels of con-tamination (Table 2). The values of tentatively permis-sible concentrations of HMs were exceeded by morethan 120 times for Cu, 36 times for Ni, and 23 times forCo [11]. Such a high content of HMs in the lawn soilswas probably due to the use of initially contaminatedsoil material. The total contamination index Zc in thelawn soils of Norilsk allows us to classify the contami-nation level as dangerous and extremely dangerous [8].

It is important that the strongly contaminated soilsof the lawns, unlike the natural soils, remain in a drystate for a long period, which increases the danger oftheir wind erosion with the involvement of considerablemasses of the highly contaminated dust into the above-ground air. Three zones of soil contamination with

Table 1.

Some physicochemical properties of surface horizons of tundra soils (0–5 cm)

Soil samples, distance from Norilsk Moisture, % Ac, mmol/100 g Loss on ignition, %

Background soil, 100 km 58 35.9 5.12 19.78

Tailing dump 1, 1 km 95 17.1 7.5 17.25

Tailing dump 2, 1 km 82 41.1 4.27 19.76

2 km from Norilsk 108 61.6 4.9 49.86

4 km from Norilsk 97 17.1 7.05 36.38

6 km from Norilsk‡ 84 78.8 4.9 47.53

9 km from Norilsk 62 60.2 5.22 38.69

12 km from Norilsk 78 64.4 5.27 28.33

14 km from Norilsk 56 64.4 4.95 27.46

15 km from Norilsk 52 35.1 6.06 27.67

Mayak Mine, 20 km 76 27.4 7.35 23.21

Komsomolsk Mine, 25 km 48 21.4 5.87 28.62

* Ac – total acidity.

pHH2O

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heavy metals were delineated around Norilsk. The zonewithin 4 km from the city is characterized by a highcontent of HMs; the concentrations of mobile(extracted by the acetate ammonium buffer) HM com-pounds in them exceed the corresponding maximumpermissible concentrations (MPCs) by 30–50 times forCu, 20–30 times for Ni, and 2 times for Co. The MPCsfor water-soluble forms of Cu and Ni are exceeded by4–5 times (Table 3). In the zone of 4–16 km from thecity, the concentrations of mobile HM compoundsexceed the MPCs by 10–20 times, and the concentra-tions of water-soluble compounds exceed the MPCs by2–3 times. In the zone of 16–25 km from the city, theconcentrations of water-soluble forms of HMs do notexceed the corresponding MPCs, but the concentrationsof mobile and acid-soluble forms of HMs remain highand suggest the possibility of the migration of HMswith surface runoff and their excessive uptake byplants.

The soil contamination with HMs under the impactof tailing dumps has a local character. The concentra-tions of Cu, Ni, and Co in the soils sharply decreasewith an increase in the distance from the particulardump (Fig. 2). Thus, at a distance of 350 m from tailingdump 2, the total Cu content in the surface soil horizondecreased by more than seven times. At the same time,the Ni content remains relatively stable. Dumped rocksof different compositions have different effects on thestate of the surrounding soils. Dumped stripping rocks

generally exert a lower impact on the surrounding terri-tory in comparison with tailing dumps. Thus, the Cuand Ni concentrations in the soils around the dumps ofstripping rocks near the Mayak mine were low; in thearea of the Komsomolsk mine, they exceeded the MPCsby up to eight times. It is important that the localizedcontamination spots around the tailing dumps mayincrease with time due to the addition of new portionsof tailings and the leaching of contaminants. As theconcentrations of water-soluble forms of HMs exceedthe MPCs by 8 times for Cu and 3 times for Ni, the pos-sibility of further migration of these pollutants and theirpenetration into the local waterways cannot beexcluded.

Thus, the surface horizons of soils around Norilskare strongly contaminated with Cu and Ni compoundsdue to the aerial pollution; tailing dumps representadditional local sources of HM pollution.

The distribution of HMs in the soil profiles is char-acterized by two maximums. The first maximum is inthe upper organic horizon. It is caused by the aerial pol-lution of the soils from the top and by the biogenicuptake of the elements. The second maximum is oftenfound in the lowermost horizon; it is related to themigration of HMs with descending water flows andtheir accumulation above the permafrost table (Fig. 3).

The distribution patterns of HMs in the soil profilessomewhat differ in dependence on the soil profile mor-

Table 2.

Concentrations of heavy metals in lawn soils of Norilsk, mg/kg

Location Zc Cu Ni Co Mn Fe

Ul. Mira 1

49.7 4000 935.1 384.2 3194 28390

Leninskii pr. 40

155.9 14000 2455.0 960.4 2845 69650

Leninskii pr. 28

70.2 3600 1543.0 1181.0 2702 89390

Leninskii pr. 18

181 16000 2915.0 1144.0 2094 73150

Leninskii pr. 17

68.4 5000 1278.0 727.2 2826 49260

Ul. Talnakhskaya 43

118.6 9700 2188.0 890.7 2189 61030

Ul. Talnakhskaya 17

172.4 15000 2837.0 1164.0 2403 77680

Ul. Kirova 18

66.9 5100 1195.0 668.9 2591 45680

Ul. Pavlova 15

75.7 6200 1263.0 645.8 3003 46210

Ul. Laureatov 47

104 8300 1823.0 914.9 2458 66180

Ul. Laureatov 65

146 13000 2336.0 912.9 2547 64010

Ul. Sovetskaya 5

76.8 4200 1634.0 1229.0 2731 90250

Ul. Sovetskaya 16

76.3 6300 1273.0 633.7 3060 44560

Ul. Sovetskaya 25

44.8 3300 870.3 443.9 3309 31750

TPC and MPC(*) for the total content of HMs in neutral and slightly acid loamy and clayey soils with the pH of the salt extract >5.5

132 80 50* 1500*


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phology and the major source of pollution. A distinctsurface maximum is typical of the soils subjected to theaerotechnogenic pollution.

In the polluted soils, the total content of Cu in thesurface horizons is higher than the contents of Co andNi, which is explained by the high concentration of Cuin the industrial emissions. In the background soils, theNi content usually exceeds the Cu content indepen-dently of the type of soil-forming material.

Our data suggest that HMs entering the soil surfaceactively penetrate down to a depth of 25 cm. However,in some cases, the entire soil profile down to the perma-frost table is contaminated. This was the case in thesoils of a sampling plot 4 km from Norilsk. In them, the

above-permafrost maximum in the Cu contentexceeded the normal Cu content in the above-perma-frost horizons by 10–12 time.

Thus, the distribution pattern of HMs in the studiedsoils attests to their input from the air. The second max-imum above the permafrost is due to lateral and verticalmigration of HMs.

Data on the fractional composition of Cu, Ni, andCo compounds in the soils allow us to judge the migra-tion capacity of these metals and the role of differentsoil components in their sorption. Soil contaminationunder the impact of airborne pollution changes themobility and fractional composition of HM compoundsin the soils. Minimum concentrations of HMs are found

Table 3.

Statistical parameters of HM concentrations of HM compounds in surface soil layers (0–5 cm) at different distances fromNorilsk

Distance from Norilsk, km

Extract from soil

1N HNO

3

AAB water

ë

u

Ni Co ë

u

Ni Co ë

u

Ni Co

1 972.7 512.4 59.48 110.6 45.92 10.66 4.14 1.43 0.012 166.7 275.2 49.85 22.4 123.6 3.02 3.72 1.83 0.373 440.2 285 16.05 147.6 65.97 4.644 0.09 0.09 0.014 1700 606 268 158.8 39.2 5.2 0.46 1.99 0.04

Average

819.90 419.65 98.35 109.85 68.67 5.88 2.16 1.33 0.11

Standard deviation

584.97 143.46 99.27 53.55 33.21 2.87 1.86 0.65 0.15

V

*

, % 71.35 34.19 100.94 48.75 48.35 48.85 82.48 56.71 141.446 152.6 62.58 12.62 26.55 16.62 1.86 1.7 0.4 0.028 218.1 50.75 6.05 32.42 22.92 1.27 0.91 0.22 0.0110 911.5 528.6 24.74 142 220 14 0.43 1.3 0.0312 360.5 286 29 34.3 37.5 13.8 1.64 0.42 0.0214 213.7 168.5 29 14.83 14.06 1.08 0.53 0.16 0.0115 411.5 149.5 10.42 59 39.97 2.71 3.84 1.74 0.01

Averag

e 371.28 219.29 20.28 50.02 62.22 6.40 1.04 0.50 0.02

Standard deviation

311.48 197.27 10.41 51.98 88.67 6.85 0.60 0.46 0.01

V

, % 83.89 89.96 51.31 103.91 142.51 107.02 57.68 92.42 46.4818 126.2 80.85 4.87 2.35 11.53 0.19 0.3 0.19 0.0120 469.8 147.5 10.49 148.5 65.59 3.43 1.48 1.73 0.0722 116 112 43 56 34 21 0.87 0.95 0.0225 98 103 16 12 15 4 0.4 0.5 0.01

Averag

e 199.50 110.84 18.59 54.71 31.53 7.16 0.76 0.84 0.03

Standard deviation

182.71 27.73 16.90 66.74 24.76 9.38 0.54 0.67 0.03

V

, % 92.51 25.01 90.89 121.99 78.53 131.11 70.69 79.39 104.45

TPC for the total content

132 80 50

MPC for mobile compounds

3 4 5

MPC for waste wa-ter

0.1 0.1 0.1

*

V

is the coefficient of variation.

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in the water-soluble fraction (0.02 to 1% of the totalcontents of HMs). Even in the soils with the high levelof contamination (as judged from the total contents ofHMs and the contents of their mobile forms), the con-tents of water-soluble HMs are relatively low andexceed the MPCs only in the most contaminated soils.

The contents of exchangeable forms of HMs arealso low (0.1–2.6% of the total contents). Heavy metalsare firmly fixed in the soils with a slightly acid or neu-tral reaction, and the high content of organic matter inthe surface horizons serves as a physicochemical trapfor HMs. The portion of HMs extracted by the ammo-nium acetate buffer (pH 4.8) significantly variesdepending on the level of the soil contamination and onthe particular metal. In the background soils, 0.1% ofCo and 2–3% of Cu and Ni come into this extract. Themobility of HMs increases in the contaminated soils;the portion of HMs extracted by the acetate ammoniumbuffer increases up to 20–50% of the total contents. Thestudied metals can be arranged into the followingsequence with respect to their extractability by the ace-tate ammonium buffer: Cu > Ni > Co. Hydroxides ofCu, Ni, and Co precipitate under neutral and slightlyalkaline reaction. An increase in the soil acidity wasnoted near the tailing dumps; in some cases, the soil pHdecreased to 4.1–4.6. This is probably one of the mainfactors increasing the mobility of HMs in such soils.

140

120

100

80

60

40

20

0 50 70

1600140012001000800600400200

0 25 100 250 350

Cu, Ni, mg/kg

Distance from the dump, m

Distance from the tailing dump, m

CuNi

Cu, Ni, mg/kg (a)

(b)

Fig. 2.

Concentrations of copper and nickel in soils at dif-ferent distances from the (a) dump of Mayak mine and(b) tailing dump 2 (Lebyazh’e).

1009080706050403020100

100908070605040302010

0 Äé AT B1 B2g Äé AT B1 B2g

% (a) (b)

1

2

3

4

5

6

AT ATA AB1 B1B2 B2

I

II

Fig. 3.

Fractional composition of Cu (a) and Ni (b) in the (I) background and (II) contaminated tundra gley soils. Fractions:(

1

) residual, (

2

) bound with crystallized iron compounds, (

3

) bound with amorphous iron compounds, (

4

) bound with organic mat-ter, (

5

) specifically adsorbed, and (

6

) exchangeable.


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A significant portion of HMs is bound with ironoxides and hydroxides. The portions of Cu, Ni, and Cocompounds bound with the amorphous iron oxides andhydroxides reaches 20–40% of the total contents ofthese metals (Fig. 4). This is related to the developmentof gleyzation in the waterlogged soils with a corre-sponding increase in the content of amorphous ironcompounds and the reduction of Fe

3+

to Fe

2+

. The disso-lution of bivalent iron compounds results in the release

of HMs coprecipitating with them. This factorincreases the mobility of HMs in the overwetted soils.

Crystallized iron oxides bind smaller amounts ofHMs (0.3 to 12% of the total HM contents). In the con-taminated soils, the HM concentrations in the fractionbound with the organic matter increased by 1–2 to8

−

11%.A larger part (50–80%) of the HMs in the back-

ground soils is firmly fixed in the residual fraction. In

0 10 20 30 40 50

10

20

30

40

50

60

70

80

0 500 1000 1500 2000 2500 3000

30

60

90

Cu

Ni

Co

0 500 1000 1500 2000 25003000

10

20

30

40

50

60

70

80

0 500 1000 1500 2000 2500 3000

10

20

30

40

50

60

70

80

3500

Dep

th, c

mD

epth

, cm

(a) (b)

(c) (d)

Fig. 4.

Distribution of heavy metals (mg/kg) in the profiles of the (a) background and (b–d) contaminated tundra gley soils.

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the contaminated soils, the portion of HMs in the resid-ual fraction is two to four times lower. The portion ofmobile HM compounds and HM compounds boundwith amorphous oxides and hydroxides of iron signifi-cantly increases in the contaminated soils.

Significant amounts of Cu, Ni, and Co bound withiron compounds may become mobile upon the develop-ment of reduction conditions in the excessively moistsoils. This phenomenon is typical of the tundra zone,where gley processes favor an increase in the mobilityof iron compounds and of HMs bound with them. Thisis an important factor enhancing the mobility of HMsand, hence, the possibility of their migration into waterbodies.

It is known that vegetation is strongly suppressed inthe impact zone of metallurgical plants due to theincreased contamination with HMs [5, 16]. Three con-tamination zones around Norilsk were delineated onthe basis of visual observations of the state of the plantcover. Tree vegetation was virtually absent in zone 1(<4 km). Thinned tree stands were in zone 2 (4–16 km).Dead standing trees with a partly surviving under-growth of larch and a well developed herbaceous layerwere observed within this zone in the areas of forest-tundra. Some changes in the composition of the naturalphytocenoses were also noted at distances of 16–25 km

from the metallurgical plants; in this zone (zone 3),lichens were absent. It is known that lichen species areparticularly sensitive to the aerial pollution of soils withHMs and to acid depositions (sulfur and nitrogenoxides) [22].

The biological properties of the soils also changedunder the impact of the pollution; element cycles weredisturbed. The state of the soil microorganisms and theefficiency of their functioning is an integral index of theecological state of soils. The rate of carbon emissionand the coefficient of mineralization (K min) of theorganic matter are integral indices of the biologicalactivity of soils. The values of K min in the studied soilsvaried depending on the intensity of the pollution. Inthe zone of the intense soil contamination (2–4 km fromNorilsk), K min varied from 19 to 42. The rate of min-eralization of organic matter near tailing dump 1 washigh relative to the background levels, but somedecrease in K min was observed near tailing dump 2.The rate of mineralization exceeded the backgroundvalues by 4 times near the clinker heap; this was due tothe high content of nutrients and indicated the distur-bance of the normal pattern of the organic matter min-eralization (Figs. 5, 6, Table 4).

A certain dependence exists between the K min val-ues, the rate of the CO2 emission from the soils, and the

Table 4. Rates of the organic matter mineralization in tundra soils

Sampling plot Horizon, distance from Norilsk Ash content, % Corg, % µg C-CO2/g

of soil per h K min

Slag heap AO, 1 km 36.37 63.63 23.01 39.40

Clinker heap AO, 1 km 15.57 84.43 2.14 547.96

Tailing dump 2, Lebyazh’e AO1, 1 km 13.57 86.43 6.93 173.12

AO2, 1 km 34.92 65.08 4.20 214.96

Tailing dump 1 Mixed sample, 0–5 cm, 1 km

8.57 91.43 1.69 748.3

Mixed sample, 0–5 cm, 10 km

17.25 82.75 6.93 165.75

Along the road Norilsk–Talnakh


37.87 62.13 27.29 19.27


72.54 27.46 23.83 42.29


61.31 38.69 3.76 226.35

Dump of Mayak mine Mixed sample, 0–5 cm, 20 km

38.05 61.95 2.73 315.17

Dudinka, background 22. AT, 0–5 cm, 100 km 93.33 6.67 4.57 283.43

EURASIAN SOIL SCIENCE Vol. 41 No. 6 2008


degree of soil contamination. The soils near tailingdumps are characterized by the maximum content ofcopper and the minimum value of K min. The maxi-mum values of K min were determined in the soils nearthe clinker heap despite the fact that these soils werestrongly contaminated with HMs (15 MPC for copper).In the soils polluted from the air, the dependencebetween the K min, CO2 emission, and the degree ofsoil contamination is more definite. However, the K minvalues may differ in the soils with similar concentra-tions of copper, which is explained by the variability ofthe local soil conditions, including the soil moisteningand the concentration of biophilous elements.

Heavy metals inhibit respiration in the case of theirhigh content (>5 MPC) and do not exert a significanteffect on K min upon the lower contamination levels.The concentration of biophilous elements and theregime of soil moistening have greater effects on thesoil biological activity. Such a state of the ecosystemcan be probably be characterized as the level of maxi-mum permissible disturbance; according to the K minvalues, the ecological state of the environment can berated at grade 3 according to the five-grade scale [7].Such a state is observed under the total content of HMsof less than 5 MPC and the concentrations of water-sol-uble forms of HMs below or equal to the correspondingMPCs; in the studied area, these conditions are met inzone 3 (>16 km).

The soil contamination reaching 5 MPC can be con-sidered the boundary between levels 3 and 4 of the envi-ronmental quality loss. The low values of K min in thesoils at distances of 10 to 14 km from Norilsk were dueto the high concentrations of mobile Cu and Ni com-pounds in these places. The values of K min differedinsignificantly from the control ones at greater dis-tances from the city. Despite the fact that the level ofsoil contamination was relatively high, the parametersof the biological state of the soils were close to thebackground values. All three vegetation stories (trees,shrubs, grasses and mosses) were well developed, andthe K min values were close to those in the backgroundsoils.

The impact of the contaminated soil on all therelated components of the natural systems (plants,microorganisms and their biological activity, ground-water, and atmospheric air) should be taken intoaccount in the environmental assessments. The uptakeof HMs by plants and the concentrations of mobile HMcompounds in the soils are the most sensitive parame-ters of soil contamination [16, 19]. This is especiallyimportant for agricultural soils. The development ofsurface runoff and gley processes are the most impor-tant ways of the influence of contaminated soil on theecosystems and on humans in the contaminated areassubjected to waterlogging. The activity of HM migra-tion with water flows should be calculated. In this con-text, data on the water-soluble forms of HMs are of par-ticular importance.

Zone 1 (<4 km) is characterized by the high concentra-tions of mobile (36 MPC) and acid-soluble (3–12 MPC)HMs; the concentrations of water-soluble HMs in thiszone exceed the MPC by three–four times. The absenceof trees and lichens and the pronounced disturbance ofthe organic matter mineralization are observed in thiszone. In zone 2 (4–16 km), the concentrations of acid-soluble compounds of Cu and Ni reach 6 MPC; the con-centration of their mobile compounds, 10 MPC; and theconcentration of water-soluble compounds, 3 MPC.Thinned tree stands, the absence of lichens, and thedecrease in K min are observed in this zone. In zone 3(16–25 km), the reestablishment of natural vegetationis observed, the processes of organic matter mineraliza-tion are normalized, and the danger of HM migrationinto water bodies decreases significantly. The concen-trations of HMs in the water extract do not exceed theMPC, but the uptake of HMs by plants and their migra-tion with surface water flows are possible under condi-tions of the widespread development of gleyed soils.

According to the five-grade scale for the environ-mental quality assessment, zone 1 (<4 km) correspondsto grade 5 (the maximum loss of the environmentalquality) [7]. Zone 2 (4–16 km) corresponds to grade 4.Zone 3 (16–25 km) corresponds to grade 3; the soilmicrobiological activity in this zone becomes normal,and the contents of water-soluble HMs do not exceedthe MPCs. At distance of more than 25 km fromNorilsk, the state of the environment is close to grade 2;a significant decrease in the level of soil contaminationand the presence of full-value plant communities arenoted for this zone.

In some places within the latter zone, relatively highconcentrations of mobile compounds of HMs weredetermined, and the possibility of their migration intoplants could not be excluded. However, no pronouncedfeatures of vegetation suppression were registered. It issuggested that such areas within zone 3 should be spe-cially delineated and isolated as areas at risk.

CONCLUSIONS

Zones with different levels of soil and environmentdegradation were delineated around Norilsk. The terri-tory of the city proper is strongly contaminated. Theconcentrations of copper, nickel, and cobalt in the lawnsoils of the city exceed the corresponding MPCs bymore than 120, 36, and 23 times, respectively. This isexplained by the use of initially contaminated soils forthe artificially created lawn soils and by the continuousaerotechnogenic input of HMs onto them. According tothe integral index of soil contamination Zc, the soils ofthe lawns correspond to the dangerous and extremelydangerous contamination levels.

The soils at distances of up to 4 km from the cityhave high concentrations of HMs exceeding the MPCsby 3–12 times for acid-soluble forms, by 10–36 timesfor mobile forms, and by 3–4 times for water-soluble

658


YAKOVLEV et al.

forms. This territory is characterized by the absence oftrees and the disturbance of the organic matter mineral-ization; it corresponds to grade 5 of the environmentalquality loss according to the five-grade scale.

The zone at distances of 4–16 km from the city cor-responds to grade 4 according to the degree of soil con-tamination with heavy metals, the state of the vegeta-tion, and the soil biological activity. The concentrationsof acid-soluble, mobile, and water-soluble compoundsof Cu and Ni in the soils of this zone reach 6, 5–18, and2–3 MPC, respectively. Thinned tree stands, theabsence of lichens, and the decreased biological activ-ity of soils are observed in this zone.

The zone at distances of 16–25 km from the city cor-responds to grade 3. The concentrations of acid-solubleHMs exceed the MPC by 2–3 times, and the concentra-tions of water-soluble HMs, by 4–18 times. The con-centration of water-soluble HMs does not exceed theMPC; the soil microbiological activity is close to thenorm according to the index of the organic matter min-eralization. At distances of more than 25 km from thecity, the ecological state of the environment corre-sponds to grade 2 of the environmental quality lossaccording to the state of the vegetation and the soilchemical and microbiological parameters.

A significant part of the HMs in the soils is boundwith amorphous iron compounds, and this providesconditions for the seasonal migration of HMs intowater bodies under the impact of reduction processes.

The coefficient of the organic matter mineralizationK min and the soil respiration depend on the content ofHMs in the soils: the inhibition of respiration takesplace upon the total concentration of HMs above5 MPC. At the lower contamination levels, the contentof HMs does not have a significant effect on the organicmatter mineralization.

The visual assessment of the state of the vegetationand the determination of the HM concentrations in thesoils and water extracts from them, coupled with thedetermination of the K min values, give adequate infor-mation for assessing the state of the environment. TheK min coefficient varies significantly in dependence onthe soil properties; therefore, taken alone, it cannot beconsidered indicative of the ecological situation in thestudied region.

The zone of Norilsk and its nearest environs can bequalified as a zone of ecological disaster. To decreasethe technogenic impact on the health of the population,the concentrations of pollutants in the emissions of theplants and the amounts of disposed industrial wastesshould be decreased. The soils of artificial lawns in thecity should be replaced to avoid additional pollution ofthe aboveground air with strongly contaminated dustupon the wind erosion of lawn soils.

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