TRENDS IN SOIL WATER COMPOSITION AT A HEAVILY POLLUTED SITE

EFFECTS OF DECREASED S-DEPOSITION AND VARIATIONS IN PRECIPITATION

R.D. VOGT1*, H.M. SEIP1, H. OREFELLEN1, G. SKOTTE1, C. IRGENS1, and J. TYSZKA2

1 University of Oslo, Dept. of Chemistry, P.O.Box 1033 Blindern, N-0315 Oslo,

Norway

2 Forest Research Institute,ul. Bitwy Warszawskiej 1920r Nr. 3, PL-00-

973 Warszawa, Poland

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Outline

Issue The influence of amount of precipitation on recovery response

The study siteDeposition trends

FindingsConclusions

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Influence of precipitation

The main result from a 5 years field acid addition experiment was that the Precipitation amount had a profound influence on the soil water chemistry

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Key issue

In many of the areas where there is an amelioration of the surface water chemistry following a decline i S-deposition there has also been an increase in the amount of precipitation

To what extent may increase in ANC in regions with declining S-deposition be related to variations in precipitation?

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The study site

Czerniawka in theKarkonoski National park in Poland

Coniferous

Deciduous

Mixed

Deteriorated stands

Urban area

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Decreasing large S-deposition

5.4g S m-2yr-1

between 1985 - 1996Decreased >50% since 1987No large local sources

Precipitation pH=4.3Throughfall KL =1.7

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Deposition trends

S-deposition in in the region was more than halved between 1987 and -96Rather small variations in S-deposition at the site during the studyThe annual amount of precipitation varied with almost 100%

Study period

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Soil chemistry

The %BS in the soil is very low

0

20

40

60

80

100

%

O B1 B2

Soil horizon

AlSHSBS

Horizon pHBaCl2 CECE

O 2.8 233B1 4.1 25B2 4.1 24

meq kg-1

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Soil water

Low pH values in O-horizons (average pH = 3.7)Mainly Al release buffer the pH in the mineral soilAl equivalents account for more than half of the total charge in the mineral soil solutionRCL={Al3+}/{Me2+} between 0.8 and 2 in the mineral soil

0

100

200

300

400

500

600

O A B1 B2 BCHorizons

ueq

L-1

0

100

200

300

400

500

600

ueq

L-1

H+ Al ekv Ca2+Mg2+ Na+ K+SO4 2- NO3 - Cl-

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Trends in soil water chemistry

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Influence of wetness

01234

0100200

CL

mm

92Sp92S

92F93Sp

93S93F

94Sp94S

94F95Sp

95S95F

96Sp96S

96F

-1000-800-600-400-200

0200

0

100200

ANC

mm

92Sp92S

92F93Sp

93S93F

94Sp94S

94F95Sp

95S95F

96Sp96S

96F

Particularly wet conditions give especially favourable water quality

The soilwater quality was better in fall of 1996 than in 1993 albeit similar conditions

R

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A multivariate approach

PC1Recovery & dilution⌧Wetness and Time are highly

correlated• SO4 and Cl cluster• All chemical parameters are

negatively correlated to Wetness and Time along the PC1

PC2 Spatial variation within each soil horizon

-6 -4 -2 0 2 4 6-4

-2

0

2

4

6

8

0Plott

H

I

HH

B

D

F BB

HI

J

F

I

B

DE E

H

B

FE

I

F

G

E

G I

E

G

D

G

G

E

J

H

D

B

I

FD B

G

F

E

F

F

J

D

G

E

FE

G

G

H

I

E

I H

E

B

J

D

H+

TOC

AloCa

Mg Na

K

SO4

NO3Cl

F-tot

Al-eq

Time

Wetness

Recovery & Dilution (PC1)Sp

atia

l var

iatio

n (P

C2)

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Conclusions

Indications of improved soil-water quality at a heavily S-loaded site in west Poland from 1992 - 1996

However, this is probably to a large extent due to more precipitation during the last part of the period

This should be borne in mind in studies of recovery especially if only two or a few points in time are compared