Chemical composition of soil and lake sediments - an indicator of geological processes in Lithuania

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Geatogical Quarterly, 2000,44 (4): 347-354

Chemical composition of soil and lake sediments -

an indicator of geological processes in Lithuania

Virgilija GREGORAUSKIEN~ and Valentinas KADGWAS

Gtcgorauskicn.4 V. and Kadiinas V. (2000) - Chcmical composition o f soil and lakc scdimcnts - an indicator of gcological proccsscr in Lithuania. Gcol. Quart., 44 (4): 347-354. Warszawa.

Long-tcnn multipurpose gwchcmical studics in Lithuania show that thc chcmical composition of surface scdimcnt can bcuscd s. an in- dicatorof gcological pmccss: duration of wcathcring, soil formation and thickness of sodimcnt. Thc chcmical composition of uppcr and lower soil laycrs and of lakc sediments givcs information on past scdimcntation: thc typc and agc ofQuatcmaty dcposits and thc location and dcpth of Plcistoccnc glaciulacuslrinc basins. Wc lhcrcforc havc a basclinc to prcdict changcs in surFacc chcrnistry provokcd by cur- rent anihropogcnic prcssurcs.

ViqiIga Gregorn~kienJ, Geological Survey of Litltuania, S. Konarshio 35, LT-2600 Vflnius, Lithunnia, e-mail:

vir~Iija.~egornl~~kiene@I@.lt; Valeniinrrr Kadiinas, Inslitlrte of Geology, T. Sevcenkos 13, LT-2600 Vilnius, Lithvania, s-mail:

vkudu~ias&~ologin.It (received: April 24, 2000; acccpied: August 8, 2000).

Kcy words: Lithuania, hacc clcrnents, soil, lakc scdimcnts, gcoindicators.

INTRODUCTION

The chemical composition of surface sediment is a complex indicator of various geoIogjcal processes: weathering, soil formation, sedimentation. It has long been used, though not al- ways successfully, as a means to help separate Quaternary deposits of the same genesis but of differmt age (Late Weichselian and Late Saalian) in eastern Lithuania (Balmas, 1995). More recent gemhemica1 research on the soils formed on these sediments show that soil chemical composition may, rather b~ an important geoindicator, differentiating Quaternary deposits of the same genesis which have been affected by weathering and soil forming processes of different duration (Righi et al., 1997).

The h c e element content of lake sediments depends on many factors, one being the depth at which sediment accumu- lated (see Salonen et al., 1993; Itkonen and Olander, 1997 for data from other countries). This dependence of trace element acc~unulation on lake depth can help evaluate the distribution of polIutants in reservoirs. It can also help to reconstruct the b a t h p e w of Pleistocene glaciolacustrine basins.

METHODS

This study is based mainly on data from the Geochemical Atlas of Lithuania and lake sediment investigations (Kadfinas et ad., 1999; Kadthas and BudaviEius, 1999).

Samples of four soil types (sandy, sandy-loamy, loamy-clayey and peat) were collected from the topsoil horizon (A) during the geochemical mapping of soil in Lithuania at a scde of 1:1,000,000. In the eastern Lithuanian highland 75 sandy soil, 80 sandy loam and 82 loam-clay samples were taken, while in the neighbouring AEmena-Medininkai high- land 16, 17 and 15 samples respectively werc collected. This geochemical data has been used to more precisely define the age and limits of glaciations in these highlands.

To understand the influmce of soil forming processes on

the regional chemisby, 249 samples were colle~ted throughout 53 complete soil profiIe sites (Fig. 1).

For the lake sediment investigation, the four deepest lakes in the eastern Lithuanian highland - Smalvas, Bebmsai, Luokesai and Dusia - ^werescIected The 484 lake sediment samples were t a k a in profiles crossing the deepest zones ofthe lakes (Fig. 2). Samples with Ioss on ignition above 50% were termed organic sediments, while sampla reacting with HC1

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Fig. 1, Regional diFirbuitDn ofdcium md im in topsoil and soit p m t material in Lithuania

and

having a

Sr

wntent > 200 ppm were categorisd as

MLS sediments. A content

of G a

> 7 ppm (the medim value d Ga

in

c h y md loam in Lilhmh) was m additional index ^to distinguish tdgenous clayey sediments. Median values of el&

ments were caIculated for sediment

from

three differ& lake m a : IiW < 5 m, sublittoral Is20 m, and pmftmdal> 20

m. The following element associations in sediment weredistin- guishat authigenic elements related to carbonates, phosphates, hydroxid~ that formed in si&; d o c h t h m u s -relating to

pi-

mary de,trital minerals; and soluble biogenic elements that are

biologically cycled

and

deposited mainly with organic matter.

Part of the biagenic e h t s may be Ioc-ally a n ~ p o g e n i c

in

origin and so this dement association is referred to as biogenic-dmpgenic, Allochthon0~8 trace elements addi- tionally have been disjoint to allochthmous association -the m e elements of the common minerals (qustrtz, feldspar, mica d clay mhmah) and dIochhonoug-accessory elem&

related ta the weathering-resistant minerals (zircon, rutile, il- d t e , towmahe eit,). Element associatiws are

d

ac- cording to element state and mineralogys

IF-

BastemLithuanirt (Late W c i h 1 ' m )

A'mcna-Modininksi ( h f c Saaliaa]

Cu 5.8 11.5 8.9

6.8 7.7

8.6 I

I 11 111

lH

Ga 4.6 5.6 7.4 5.3 5.4 6.7 Ag

0.064 0.068 0.064 0.076 0.087 0.083

Y 12 20 17

12.4 1 . 6 13.8

B

21.8 28.1 31.7 22.0 24,8 24.8

MY

1.6 2.0 2.4 1.8 1.9 2.0 Ea

293 369 413

296 438 357

La

19.3 23.2 31.7 18.3 21 3 22.4

Li 10.4 It,9 15.5 113 11.6 14.3 Co

3.3 4.8 6.6

3.4 4 5 4.6

Cr 21.5 31.0 42.3 23.1 26.2 32.6

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Chemical comnosition of mil and take gcdimcnlx - an iadicatur of moIa&al -D ia L i h m i a

Microelement content was determined by DC Arc

Em&

sion Spbometry in the

<

1

nmr

hction and recalculated to

&-dried materid. AnaIyticaI and mapping m h d s are de- scribed in Gregowuskid and Kdldanas (1999).

In

data processing, mdwd -tistid methods (nonparamebic, descriptive s ~c m k b ~ aud , &tar analysi6) and so- WCEL, SPSS and STATISTICA) were used Concentdon (wumulatiw) co&cients

(Kd

were detmmhd by dividing d mmicrcelement values

in

each sediment type by their median value

in

_allsediments not dBhntiated amding to their types.

CHEMICAL COMPOSITION OF TOPSOIL

AS

AN INDICATOR OF

SEDIMENT

AGE

Soil

in

the eastem Lithuanian highland

ohat

formed during the last Nemunas Glaciation (Late Weichselian) is rather d i a - ent in lme element composition h m soil in the neighbowing Mmena-Medhdai highland (Tab. I)

that

formed during

the

pmulhnate Medininkai Glaciation (Late S d a n ) (Kudaba, 1983; Baltrlhml 1995; Bitinas and SaMms, 1995). This shows the influence of wcdering and dupdinn of soil forming

processes on the disbibution of the et.aoe elemmts. ¹

I The

longer duration of these processes (about 100 thousand

years)

and

the pmighcif md&g of sediment (BasaIyb et

Y

- v

al., 1976) produced a chamkristic tmce element composition

of soils in the G - M d n b h i hifland Some m e ele- _Fig._2._Lako_sodimcnt_sampling_sitm men& (P, Mn, Ag, Zr) we present in h i g h concentrations than

DoWd linss indicata tho location of bathymctric profilca with trace elo-

in other Lithuaniw regions, while o h

(V,

Ni,

Cr,

Co, Sc) are

merit dislribu6m; isDtraths

-

scarce. Trace elements related to chy minerals tend to have been removed h m these older soils. hcreased values of Zr,

Nb,

Y, Yb

and

P

reflect a relative h m a a in the mount of ac- ments ahow ^strong correlation in soils of h e

cessory m i n d (e.g. zimm, apatite, t o d e , m f i t e ) Ahena-Medininkai highland (R > 0.8-0.9) than in soils of b during wmtkhg. The bxeased value^ of

P

and Mn can also eastem Lifhwnian highland.

En

the Ahma highland kace el&

be related to the formation of mthigenic phosphate (vivianik) men& related to weathering-mht minds (Ti-&- and

Mn

hyctrOxid%s. increased values of Mn,

Ag, Zr

and partly MI-Y-Ybh.) prevail, while in the eastem Lithmim highhd

P

and decreased values of Cr, Cq

Ni, V

as well= otha clay the mce elemam related to clay minerals mineral-related trace elements in the soils above the (Ga-Li-G-V-Ni-Co-Sc). The long periods of weathering in ef- Modhhkzi d;lacid can also be with Mgacjal fect reveal the primary relations of the weahenngresistant processes: tfiese tend to

form

loamy sandy mils with depleted minerals

h m

the time of their formation. As tha composition in chy and enriched in silt and sand. *cal ofthe Eop soil horizon differs Iiltle i?om the trace element com- signature occurs widely in Ioamy sand

in

the country. position of the pmnt material (horizon C ) ( O r e p u s l d e d These soils of different ages also show differences in the

and

& d m 1999), these peculiarities can be used as an _indi- cmlationg between trace elements flab. 2). More trace

ele

h-different age soUs of Ltthuanla

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350 Virgilija Gmgomusimd and Vdcntinas K a d U

Fig. 3. Distribution of Mu in bathymetric prpfiles (adow A-B) of l n h Bebrusai, Luokcsai, Dusia and Smalvm. Etcmcnt vatucs arc shown as cocffi- cimts ofwncentr&rm Kt

Fig. 4. Dishibution d P b , Zn, C o d V in bathymebic profiles (sections A-B) of i&w Bcbmai, Luokesai, Duia and Smalvas. EIctncnt rrrIms we shown

ap corffrcicnts ofcorrcentratien 4

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Chemical composition of soil and lakc sodimcnts - an indicator of geological prncesscs in Lithuania 35 1

T a b l c 2 Correlation and nssociations of trace elements in topsoil of eastern Lithuanian nnd Axmena-Medininkai highlands

East Lithuania - ^Y-Yb C r i G a , Ni) yb) Sc-Sr

Mrnena- - T i e , La, Cr, Y)

Medininkai Ti-7,r Y-(V, CO, Za) Yb-Co

Sandy loam

East Lithuania - Li-Ga Co-(V, Cr, Mi) (B, Ga)-(Co, Cr, V) Ni-(B,Y)

Co-Zn

Mmcna- U-(Cr, Co) 03, ~~~, ^cr) Y-3-Cr Ga-(B, Zn, Yb, Sc, Li) A g - C M o

Medininkai Ga-Pb Cr-Yb V-(Zn, Me, Yb) Ti-(Cr, Co) Ti-(Yb, La, Mn) Cr-(Pb, Nb, Rb) Loam-clay

Cr-Zn Parvaise

m l a t i o n

I

~ a s t Lithuania

I

Sr-S c-Rb-V-Ni-Y-Mr-SCu-

I

Ag-Li-Mu-PMa

I

^Zr-Ti-Nb

1

Sand

R = 1-0.9

[~edininkai

I

Sandy loam

Factors

I

^F1 F3

R = 0.89-0.8

Sand

F2

Remark: elements in the parenthesis correlate \nth element before the parenthesis but net b&wm itself

R=0.79-0.7 ,

cator of glacial sediment of similar primary cumposition but different age.

Zr-NbTi-Rb Zr-Ti-La

CHEMICAL COMPOSITION OF SOIL PARENT MATEIUAL AS AN INDICATOR OF GLACIATION

AGE AND LIMITS

ST-La-Y Sr-SwBa East Lithuania

Mmena- Medininkai

The chemical composition of the soil parent material (hori- mn Cj is less affected by soil forming processes (hurnification, Ieaching, rmnslocation) and weathering than top horizon and therefore reflects the primary composition of the Quatematy deposits more clearly. The regional dishibution of elements, particularly the major elements in the subsoil reflects the limits of the glaciations (Guob yt&, 1998). CaIcium, magnesium, iron and irace elmnents whted to clay minerals ((3, V, Ti, and Ni) in subsoil most clearly rdect the glaciation limits, especially as regards phases of the last Late Weichselian glaciation Fig. 1).

Gdr-V-CeZn-Li-Pb-Mo-Cu Ga-Mu-V-Co-Ni-Pb-Cr-Zk-B- Sn-Yb

Comparing the values of eIements in the top (A) soil hori- zon and soil p m t material (horizon C), it becomes apparent k t leaching effects dominate the soils of Lithuania. Heavy precipitation, moderate winters without soil frost and the coarse soil texture has led to rapid decomposition of primary non-silicate minerals such as calcite, dolomite and hematite forming secondary clay minerals and oxyhydroxides, .translocated fiom upper to lower soiI horizons @ e m w and Mitchell, 1991). In spite of intensive agriculture and input of trace elements via fertilisers, pesticides and pesticides into top soil, only a few dements show the lugher concentrations than in soil the parent material (Tab. 3). Increased levels of silver, lead and zinc in the upper soil layer by cornparision with parent m a t h 1 may be anthropogenic in origin, partidar1y in or- ganic-rich soil. This can be related to regional and transregional pollution (GregoraushenC et al., 2000). T h e top of horizon A represents the oldest part of the soil profile, and so usually con- tains the most weathered material. Thereiore, relatively higher concentrations of Zr, Ba, Nb related to weathering-resistant

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352 Virgilija Gregorauskienh and Valmtinas Kadfinas

T a b l e 3 Median vaInes of tram and macroelcments in soil arent material

(horizon C ) and topsoil (horizon .4f

minerals occur Rae. Such chemical ratios between soil top layer and parent material may be used as indicator of the char- acter and intensity of soil forming processes.

TRACE ELEMENT COMPOSITION OF LAKE SEDIMENTS AS AN INDICATOR OF THE DEPTH

BATHYMETRY

Elements

4 2 B Ba

Co Cr Cu Ga Y

yb EA Li Mn Mo Nb Ni P Pb Rb Sc Sn Sr Ti V

Zn

Zr

% Ca Mg

Na K Fe Al

Investigation of the trace element composition of sediments in deep (> 20 rn) Lithuanjan laka (Fig. 2) has s h m that the depth of sedimentation relates to the distriiutien of trace de- ments: there are depth-related increases in the concenlmtions of elements such as Mn, Pb, Co, Zn, V, Sn, Ni, Ag, Mo (Tab. 4).

Ratio of medians

Trace elements v a l u ~ are lowest in the littod (to 5 rn deep) sediments, except far Sr and Nb.

In

the nearshore zones of some lakes, increased Ievels of Zr and La reflect natural heavy mineral concentrates in the wave zone. Various trace elements accumulate in sediment of the subIittora1 zone (5-20 m deep):

allochthonous Sc, Ga, _3,_Cr,Li, allochthonous-accessory Ti, Zr, Y, La and Ba of carbonates. Most trace elements accumulate in profundal (> 20 m deep) sediment and biogenic- anthropogenic Mq Mn, Pb, Zn, Sn, Ag clearly prevail here (Ag. 3). Allochthonous and mobile Co and Ni are also present (Fig. 4). Levels of these elements directly correlate with the depth of sedimentation. The m eelements acc~unulate differ- ently in different sedimentary facies: in calcareous and organic-rich sediment t h y mostly occur in the deepest zones, and in clayey sediment in shallow and transitional zones. The greater the depth of sedimentation the higher the levels of mobile trace elements sorbed on to the sediment.

Allochthanous-acoessory trace elements Ti-Zr-Nb- Y-Yb-La show the strongest correlation in all sediments while the alIschthonous &ace elements V-Ni-Cr-Ga-Sc show weaker correlation. Trace elements show the strongest correlation @or- relation mfficient of > 0.8-0.9) in caIcarsous sediment, and the least correlation in clayey sediment. Thus, authigenesis re- veals the most stable primmy relations, in weathering-resistant minerals, and among closely connected trace elements those which are mineral-forming or are an isomorphous admixture.

The deeper the sedimentation, the stronger the correlation among trace elements, particularly in orpic-rich and calcareous sediment. This reflects the importance of allochthonous-accessory trace elements in organic-rich sedi- ment, and a2lochthonous-accessory and biogenic- anthropogenic trace elements in calcareous sedment. In ctayey sediment this pattern is not so distinct.

The trace element compositions and ratios can, m this ba- sis, be used to reconstruct glaciolacustrine basin bathymew.

Elevated values of Zr, Nb, Y and Yb (Kadiinas ei aL, 1994) re- late to sediments deposited at shallow depths, while increased values of Cu, Zn, Mo, Mn indicate deeper zones.

Median

0.066 45.8 291 8.4 49.9 10.7 9.6 14 2.6 30.8 19.2 457 0.94 12.9 24.4 536 15.0 75 6.8 2.11 96.5 2733 60.0 35.0 190

2.37 1.01 0.42 2.05 1.59 3.77

N C 1.45 0.66 1.17 0.80 0.U 0.73 0.81 0.80 0.84 0.81 0.90

CONCLUSIONS values

T - C

0.096 30.3 341 6.7 40.9

7.8 7.8 15 2.2 24.9

,

17.2 469 0.75 13.3 14.2 495 18.9

65 6.0 2.3 1 81.5 2705 40.6 32.8

---256 -- ---

0.46 0.30 0.43 1.80 1.23 3.09

CIA 0.69 1.51 0.85 1.25 1.22 1.38 1.24 1.25 1.18 I 2 4 1.11

Trace element composition of topsoil reflects the duration of soil forming processes, and t h i s the age o f Quaternary deposits. Young soils of eastern Lithuanian highland that formed en the Late Weichselian marginal deposits possess a ielatively lugh content of trace elements in relation to clay minerals. By cornpanson, the older soils of the AZmma-Medininkai highland which rest on the Late Saalian genetically similar deposits contain higher amounts of trace elements, related to weathering-resistant minerals, and elements rekited to secondary phos- phates and manganese hydroxides. This is also a consequence of long-term periglacial processes, which changed the rnineral- ogical and textural composition of surface _sediment.Therefore the dominant soils in the Aimena-Medininkai highland are monotonous in t e x m (sandy loam) with larger amounts of quark, zircon, apatite, tourmaline and stamlite.

1.03 0.80 1.03 0.58 0.92 1.26 0.86 0.87 1.09 0.84 0.99 0.68 0.94 1.35

0.19 0.29 1.01 0 &8 0.77 0.82

0 97 1.25 0.97 1.71 1 .OS 0.79 L.16 1.15 0.91 1.18 1.01 1.48 1.07 0.74

5.21 3.42 0.99 1.14 1.30 1.22

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Chemical composi~ion of soil and lake sediments - ^anindicator of ~ o l o a i c a l proccsscs in Lithuania 353

T a b l c 4 Accurnulutive associations of truce elemenb In different type and depth of lake sediments

Coefficients of concentration of tram elements presented in subscript. They are calculated by formula: Kk = CJCb where: C - median values o f trace element in different type and depth or lake sedimenls,Cr- exponent median value of trace dement in the four investigated lakes scdiments

The chemical composition of the soil parent material can precisely reflect the age of Quaternary deposits and so be u s e l l in defining gIaciation limits. Comparing the chemical composi- tion of topsoil: and of parent material helps ascertain the domi- nant washout-leaching pmcess in the sails of Lithuania:

concentrations ~f bace elements in topsoil are 8% lower on av- erage, and of macroelements are 34% lower, than in parent ma- terial. Only concentrations of wace eIemmts reIated to weathering-resistant minerals (Nb, ,Zr, Ba) and kogenic-anthropogenic eIements @An, Ag, Pb, Sn) are hgher

in topsoil than in subsoil, indicating the impact of airborne pol- Iutants.

Trace element contents in lake sediments depend on sediment ^type and correspondingly on the depositional environment, Therefore patsems of chemical Yatiation in mod- em lake sediments can be used to reconstruct Pleistocene glacioIacustrine basin bathymelry. Increased values of Zr, Nb,

Y

and Yb may be related to the sedimentation in shalIow zone, while the increased levels d Cu, Zn, Mo, Mn characterize the sedimentation of deeper zones.

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