PH: S0273-1223(98)OO208-X

e> Pergamon WaL ScL Tech. Vol. 37. No. 6-7, pp. 273-281,1998.iC> 1998 IAWQ. Published by Elsevier Science Ltd

Printed in Great Britain.0273-1223/98 $19'00 +0'00

RISK ASSESSMENT OF HEAVY METALCONTAMINATION IN DANUBESEDIMENTS FROM HUNGARY

K. Gruiz*. A. Muranyi**. M. Molnar* and B. Horvath*• Department ofAgricultural Chemical Technology,Technical University ofBudapest, 4 Saint Gellert Square, Budapest, H-I I I I Hungary•• Soil Science Department, Research Institute for Soil Science and AgriculturalChemistry ofthe Hungarian Academy ofSciences, 15 Herman Otto, Budapest,H·I022 Hungary

ABSTRACf

The aim of the current research is to establish a suitable Environmental Risk Assessment (ERA) scheme forDanube sediments in Hungary by determining contaminants' concentrations by chemical analysis and byassessing their ecotoxicological effects. Seventeen sedimentation sites were identified, mainly upstream ofBudapest. between river kilometres 1811 and 1586. The heavy metal contents and basic properties ofsediments were determined. Excess heavy metal content was used to characterize the extent of heavy metalcontamination. Direct contact biotests were developed for testing the toxic effect of contaminated sediments.Ecotoxicological effects were measured by three bacterial tests and one plant bioassay. Effect Concentrationswere determined by the inhibition of the bioluminescence of Photobacterium phosphoreum. The resultantinhibition of different partial toxic effects was characterized by Cu equivalent. Chemical andecotoxicological results were studied together, making it possible to characterize the extent of the pollutionand its biological effects at the same time. It was concluded that combined chemical and ecotoxicologicalcharacterization of contaminated sediments may serve as a strong basis for assessing the site-specific risk ofheavy metal pollution. @ 1998 IAWQ. Published by Elsevier Science Ltd

KEYWORDS

Danube sediments; ecotoxicological tests; environmental risk assessment; heavy metal contamination;sediment quality; surface water monitoring.

INTRODUcnON

In Hungary neither legislation nor quality criteria exist for sediments of surface waters. Sediments orsuspended matter of the surface waters are not monitored or measured regularly. The potential risk ofcontaminants in the sediments of the river Danube has been indicated by previously reported measurements(Equipe Cousteau. 1993).

The estimation of a risk quotient by PECIPNEC ratio = Predicted Environmental Concentration I PredictedNo Effect Concentration (ED TOO. 1995) cannot be suggested because the Danube flows through severalcountries and primary data (like production. processing or discharge concentrations) from other countriesupstream of the Hungarian border are not available. This means that PEC value cannot be estimated from

273

274 K. GRUIZ et al.

relevant data. It is also difficult to estimate the local loading due to production or processing because thestructure of industry in Hungary has changed greatly in the last ten years. Heavy industry and mining hasbecome less active with the processing and use of heavy metals taken over by partly uncontrolled privateenterprises and small industries. At present no valid database for production and processing is available inHungary. In addition, past industrial activities still arise problems today. The enforced industrialisation inthe 50s and 60s contaminated the Danube sediments which could be considered as a chemical time bomb.

In a previous survey (VITUKI, 1971), at 36 sites on the right and 30 sites on the left bank out of theinvestigated 415 transects, the bottom sediment contained more than 10 per cent fine fraction. These siteswere selected as local sedimentation places in stagnation zones and side arms of the river. River morphologyand sediment characteristics show important changes in the Upper-Danube section due to the operation ofthe Gabcikovo (Slovakia) hydroelectric power plant. A survey (Hock and Uszl6, 1990) of sedimentcontamination detected high As, lo, Hg, Cd, Cr, Mn, Ni, Pb, Cu, Fe concentrations. Highest levels werefound in the tributaries. Equipe Custeau (1993) investigated country border sections, "hot spots" close tomajor cities, industrial complexes, dams and main tributaries. Heavy metal concentrations were very high insediments originating from the Hungarian section of the Danube.

Characterization of Danube sediments by chemical and ecotoxjcolo~ical methods

In order to characterize the risks of heavy metal contamination in sediments, it is necessary to take intoconsideration that the effect on the ecosystem - or even on some single components of the ecosystem •cannot be estimated from the measured concentration of a toxic compound alone. Sediments containmixtures of compounds which may react with each other or with the sediment matrix, producing synergeticor antagonistic effects, increasing or decreasing toxicity (Calow, 1993). The quality of the sediment alsoinfluences the toxic effect because the different binding surfaces modify the bioavailabiJity of contaminants.

Detailed characterization of sediments has been undertaken as part of a complex research project aiming todevelop a site specific risk assessment method for heavy metal contamination.

METHODS

Sediment samp!jn~ sites

Seventeen bottom sediment samples were collected in March 1966 between river kilometres 1811 and 1586in Hungary, from the mainstream of the Danube and its tributaries. The objectives of the sampling strategywere to get a general overview and to find the possible "hot spots". The maps (Figs 1 and 2) show the mainsedimentation areas in Hungarian surface waters and the sampling sites upstream of Budapest.

Figure I. Sedimentation areas in Hungary.

Characterization of the sediments

Heavy metal risk assessment in Danube sediments

------- -- - - -- - - - -- -,III,I

III

J:-:;:..I

Figure 2. Sampling plan for risk assessment

27S

The sediments were characterized by a wide range of analytical methods to get detailed knowledge abouttheir chemical and biological (ecotoxicological) properties and behaviour. In this study some chemical andseveral ecotoxicological results are presented.

From the chemical analyses the total heavy metal contents are shown which were determined by HFdigestion method. The heavy metal contents were measured by ICP-AES. From the basic properties thehumus, clay and CaC03 contents are demonstrated.

Ecotoxicolo&ical testjn&

Direct contact biotests were developed for testing the toxic effect of contaminated sediments. Three bacterialand one plant bioassay were applied.

Agar diffusion test method with Bacillus subtilis was developed at the Technical University of Budapest,using a sensitive bacterial strain considered to be sensitive for heavy metals (Gruiz and Vodicska, 1993;Gruiz, 1994).

Dehydrogenase enzyme activity test with Azotobacter agile direct contact test was developed as amodification of the Hungarian Standard 21978/30-1988.

Sinapis alba germination and root elongation test is a modification of the Hungarian Standard 21976/17•1993.

Bioluminescence of Photobacterium phosphoreum shows a decrease in the presence of toxic substances. Theluminescence light intensity was measured before and after the addition of the sediment sample and itsdilutions to the cell suspension. The decrease of luminescence intensity (H%) was calculated. From thedifferent dilutions the Effect Concentrations were determined. EC20 and ECso values represent 20% and50% inhibition of the bioluminescence.

The resultant inhibition of different partial toxic effects was characterized by Cu equivalent. Cu equivalent isinterpreted as the Cu concentration that results in the same toxic effect as the contaminated sedimentcontaining several heavy metals and toxic compounds. The inhibition in Cu equivalent was determined bymeasuring the inhibition of a Cu standard dilution series (in water) in each case together with the samples.The calculation was as follows:

Cu equivalent (mg kg-I) = [EC2o Cu/E~o sample +ECso Cu/ECso sample] : 2.

276 K. GRUIZ et al.

RESULTS AND DISCUSSION

Monitorin~ data for risk assessment

Surface waters and waste waters have been monitored in Hungary for the last 4-5 years, so the availableresults could be used as part of the risk assessment.

Estimation of the risk of heavy metals in sediments from measured data of waste water. The use of wastewater data to assess the risk of heavy metals in sediments are demonstrated for Cu data from 1995. Otherheavy metals show similar trends.

The total load into the Danube derived from waste water can be calculated from discharge data.The total Cu load upstream of Budapest in 1995 was: 2400 kg / yearThe total amount of waste water in Hungary in 1995 was: 828 000 000 m3 / yearThe average flow rate of the Danube is: 2044 m3/sec: 64 460 000 000 m3 / yearCalculated average concentration of Cu in waste waters upstream of Budapest is 6.0 Jl.g lot.The dilution is I : 78. PECCu in water, due to waste-water inflow, corresponds to 0.077 Jl.g I-t.For the calculation of PECsed from PECwater the sediment-water partition coefficient (KswCU> of 50 I g-twas used (WQDB. 1988). PECcu in sediment is 3.85 mg kg-to

The average measured values in the Danube are: CCu water =2-25 Jl.g I-I, CCu sediment =2-50 mg kg-I.

Comparing the PECs with measured concentrations, the difference is considerable. This fact could beexplained by inputs from other countries upstream of Hungary and/or from continuous accumulation ofpollutants in the bottom sediments. The difference can also be caused by the fact that sampling and pollutionare usually not performed at the same time. This is particularly true for contaminants which are stronglybound to the sediments, like heavy metals.

Estimation of risk of sediments can be calculated from monitoring data of surface water. Table I containsDanube water data from the 1995 monitoring system (Hungarian Standard, 12749), with additional results ofsediments taken from the same sites another time and the calculated K swCu values.

Table I. Monitored copper content of surface water and additional sediment data

Danuberiverkm

1848.41806.21802.01761.01717.01707.01659.01560.01479.0

Ccu water

monitored(~g 1'1)22.523.424.627.924.64.22.92.02.1

Ccu sedimentmeasured(mgkg-I )

22.92.5

39.050.021.943.047.0

no datano data

KswCucalculated

Og-I)1.01.01.61.80.9

10.216.2

Water monitoring data are characteristic. Copper contents of water entering Hungary (and other metals, notshown) were high, but decreased continuously downstream from 1761 river km. The measured Cu contentsof sediments are lower than the calculated ones if the monitored Cu concentration of surface water and themean Ksw value of 50 1g-t measured in the Netherlands are used.

Heavy metal risk assessment in Danube sediments 277

This indicates that a partition coefficient cannot generally be used for different sedimentation sites since Kdepends on the physical-chemical characteristics of sediments and on environmental conditions as well. sw

As a consequence, it is necessary to characterize the sediments in detail and to determine site specific Kswvalues in order to evaluate the risk of heavy metal contamination in a proper way.

The determination of PECsed requires basic data for sediments. The estimation of the toxic effect on theaquatic ecosystem necessitates more information about the contaminants and their bioavailability.

Heayy metal concentratjons and sedjment characteristics

Sediment characteristics are principal in the adsorption of microcontaminants and in influencing ecotoxicityby modifying bioavailability. For instance, in case of heavy metals - among others - the clay content andorganic matter content of sediments influence their total absorbed amount and their soluble fraction (Table2). The sediment samples may exhibit considerable inhomogeneity, even in case of samples which originatefrom sites close to each other.

The heavy metal (HM) contents of sediments were determined. In order to characterize the acceptable heavymetal concentrations, target values were calculated. Target values indicate the environmental quality levelfor a given environmental compartment at which the risks of adverse effects (risks to ecosystems, functionalproperties of the environment and other compartments, etc.) are considered to be negligible. The targetvalues of heavy metals were calculated for each sediment taking into account their clay and humus content(VROM. 1991).

Table 2. Basic characteristics of the Danube sediment samples

River Site location River CacoJ humus Mechanical composition (%)km content Sand Silt Clay

% % >0.05 0.05-0.002 0.002>rom rom rom

Danube Szap 1811 20.5 2.4 22.8 66.1 11.0Danube Medveright 1802 14.5 0.2 92.0 5.6 2.5MosonArm Venek left 2 km 1794 6.5 3.2 39.0 42.8 18.2MosonArm Venek right 2 km 1794 11.0 1.3 79.0 14.9 6.1Concocreek Acs2km 1717 23.0 3.5 48.6 36.1 15.3Danube Upstr. Komarom 1770 16.0 0.7 85.5 10.2 4.4Danube Downstr. Komarom 1761 14.0 2.0 74.1 18.2 7.7AtaJer creek Mouth 1.5 km 1750 16.5 1.5 84.0 10.3 5.7Kenyermezei cr. Mouth lkm 1722 19.0 4.2 23.2 55.3 21.5Danube Esztergom 1716 23.5 4.3 42.0 45.2 12.9Danube Basaharc 1707 21.5 3.3 46.0 44.3 10.0Danube Visegrad 1694 16.5 2.2 52.5 38.5 9.1Danube PtlnkOsdfUrd3 1658 19.5 2.2 72.7 22.4 5.0Danube MO Bridge left 1632 17.5 1.5 78.1 15.7 6.2Danube MO Bridge right 1632 21.5 2.2 65.5 27.4 7.1Soroksar Arm Gubacsi Br. 53.9km 1586 22.0 1.0 96.3 2.8 0.8Soroksar Arm VITUKI 57.3 km 1586 17.7 0.8 42.5 46.0 11.5

278 K. GRUIZ et al.

Table 3. Excess heavy metal contents in the sediment samples

River Site location River Excess heavy metals (mg kg· i )km Cd Co Cr Cu Ni Pb Zn ~+

Danube Szap 1811 -0.19 3.80 -4.33 13.71 17.85 -34.81 21.99 57Danube Medveright 1802 -0.27 1.17 -33.92 -15.87 -2.39 3.63 -5.65 5MosonArm Venek left 2 km ·1794 0.09 3.11 -21.85 3.76 5.59 -47.79 31.71 44MosonArm Venek right 2 km ·1794 0.32 2.22 -31.97 -10.50 -2.60 -44.01 -6.58 2Concocreek Acs2km ·1777 -0.41 -5.03 -53.37 -12.57 -10.03 -57.35 -44.26Danube Upstream Komlirom 1770 -0.29 1.53 -32.93 -13.90 -3.21 -44.75 -12.18 2Danube Downstr. Komlirom 1761 -0.25 -0.50 -35.43 -10.55 -2.61 -37.07 3.91 4Ataler creek Mouth 1.5km ·1750 -0.25 -0.24 -32.89 -12.34 -8.70 -36.75 3.54 4Kenyermezei Creek mouth lkm ·1722 3.18 -1.49 -30.67 162.74 8.28 -44.53 40.69 215Danube Esztergom 1716 -0.29 1.20 -27.78 -3.36 1.45 -21.07 49.67 52Danube Basaharc 1707 -0.27 2.68 -25.23 -3.25 3.65 -46.89 37.71 44Danube Visegrad 1694 -0.33 2.76 -27.67 -4.80 2.22 -43.95 26.53 31Danube PUnkOsdfUrd5 1658 -0.22 3.70 -29.03 -7.52 2.74 -41.09 29.16 36Danube MO Bridge left 1632 -0.16 2.33 -24.79 2.13 0.72 -33.69 57.37 63Danube MO Bridge right 1632 -0.10 2.21 -27.11 3.70 2.74 -27.87 52.80 62Soroksar Arm Gubacsi Br. 53.9km ·1586 0.20 -2.84 12.43 -3.20 -1.61 175.19 15.25 203SoroksAr Arm VITIJKI 57.3 krn ·1586 -0.18 4.24 10.94 36.07 17.52 8.40 200.6 277"Target values for heavy metals 0.80 20 100 36 35 85 140

·Danube river kilometre in case of tributaries shows the inflow of Danube-arms or creeks into main Danube."The last row shows the target values for a standard soiVsediment. with 25% c1ay- and 10% organic mattercontent (VROM, 1994).

The calculated target values were compared with the measured heavy metal concentrations because theirdifference indicates whether the measured heavy metal contents were higher or lower than the acceptablelevel.

Excess heavy metal content = Measured heavy metal content - Calculated target value

If the excess heavy metal content is positive the measured heavy metal content exceeds the calculated targetvalue, the heavy metal content is higher than the acceptable level and it may have adverse effects on theaquatic ecosystem. If the excess heavy metal content is negative the measured heavy metal content does notexceed the calculated target value, the heavy metal content is lower than the acceptable level and probably itmay not have unfavourable effects on the aquatic ecosystem.

Heavy metal contamination was characterized by the positive excess heavy metal contents and their sum(Table 3). Cd and eu had the highest concentration in the extremely contaminated sediment of the littleKenyermezei creek, which flows into the Danube at 1722 river km. The risk of this contamination is high forthe creek, but much lower for the Danube, as the dilution rate is about: I: I000. Co, Ni and Zn contents werehigher than the target values in many sediment samples.

According to the sum of the positive excesses of the single heavy metals, three "hot spots" could beidentified. The first is the above mentioned little Kenyermezei creek. The other two hot spots are located inthe Soroksar Danube Arm, South from Budapest. None of them are situated in the main stream of theDanube.

Ecotoxjcolo~ical results

Bacillus subtilis and Sinapis alba growth tests were not sensitive enough for Danube sediment samples(Table 4). All of the samples resulted in growth stimulation.

Heavy metal risk assessment in Danube sediments 279

Table 4. Results of the biotests

River Site location River Ecotoxicological testskm Bacillus Azotobacter Sinapis Photobacterium

subtilis agile alba phosphoreumEC20 ECso

mgkg'\ mgkg'\

Danube Szap 1811 + <1 50Danube Medveright 1802 + 34 >50MosonArm Venek left 2 km 1794 + 5.5 28MosonArm Venek right 2 km 1794 +/- 28 >50Concocreek Acs2km 1777 +/- 50 >50Danube Upstream KomArom 1770 +/- 26 >50Danube Downstream Komarom 1761 +/- 20 >50Ataler creek Mouth 1.5 km 1750 + 50 >50Kenyermezei cr. Mouth 1 km 1722 + <I 1.9Danube Esztergom 1716 + 1.5 50Danube Basaharc 1707 +/- 1.8 50Danube Visegnid 1694 + 22 35Danube POnkOsdfilrd6 1658 + 50 >50Danube MO Bridge left 1632 + 16 50Danube MO Bridge right 1632 + 7.0 48SoroksAr Arm Gubacsi Br. 53.9 km 1586 + 2.1 9.2SoroksAr Arm VITUKI 57.3 km 1586 + 2.7 12.3

+: inhibition +/-: slight inhibition -: no inhibition or stimulation

Azotobacter agile bioassay was too sensitive. All of the sediment samples inhibited the dehydrogenaseactivity of the test bacterium. The other disadvantage of this method was that inhibition was not proportionalto the dilution of the sample.

Photobacterium phosphoreum bioluminescence was the most suitable bioassay, because it is able todistinguish between more or less contaminated and uncontaminated samples, giving a selective answeraccording to chemical analytical results.

Table 5 demonstrates the sum of the heavy metal excesses, the clay content of sediments and the results ofthe Photobacterium phosphoreum bioassay, given in a Cu equivalent.

Comparison gives evidence for the "hot spots", showing the highest values of heavy metal contaminationand toxicity. These three sites, the mouth of Kenyermezei creek, and the two sampling points in SoroksArDanube Arm, are characteristic sedimentation areas.

In case of the other sediment samples - in which neither the heavy metal content nor the toxicity are too high- a correlation can also be found between the Cu equivalent and the sum of the heavy metal excesses. Whenthe chemical and ecotoxicological results do not fit well enough, other contaminants (e.g. organicmicropollutants) may be present or the environmental conditions may influence the effects.

It can be seen from the results that on the one hand local loading of heavy metals is responsible for the highheavy metal content and toxicity, but on the other hand the presence of sediments and their basiccharacteristics are also important factors. Local loading and hot spots appear mainly in tributaries. The mainstream of the Danube shows a more balanced picture.

280 K. GRUIZ et al.

Table 5. Comparison of chemical and ecotoxicological results and sediment characteristics

River Site location Riverkm 1: + heavy clay Cumetals content equivalentmgkg- t % mgCukg-t

Danube Szap 1811 57 11 16Danube Medveright 1802 5 3 10MosonArm Venek left 2 km ·1794 44 18 28MosonArm Venek right 2 km ·1794 2 6 10Concocreek Acs2km ·1777 0 15 8Danube Upstream KomArom 1770 2 4 11Danube Downstream Komarom 1761 4 8 12Ataler creek Mouth 1.5 km ·1750 4 6 8Kenyermezei cr. Mouth lkm ·1722 215 21 273Danube Esztergom 1716 52 13 16Danube Basaharc 1707 44 10 16Danube Visegrad 1694 31 9 15Danube PtlnkOsdfilrd3 1658 36 5 8Danube MO Bridge left 1632 63 6 12Danube MO Bridge right 1632 62 7 15SoroksAr Arm Gubacsi Br. 53.9 km ·1586 203 1 75SoroksAr Arm VITUKI 57.3 km ·1586 277 12 55

CONCLUSIONS

The heavy metal contents and basic characteristics of the Danube sediments were characterized in detail. Awide range of ecotoxicological tests was carried out: three bacterial tests and one plant bioassay wereapplied. Chemical and ecotoxicological results were studied together. making possible to characterize theextent of the contamination and its biological effects at the same time. The chemical as well as theecotoxicological characterization of sediment pollution was found to serve as a strong basis in the future forthe

development of a suitable risk assessment scheme relevant to Hungarian Danube sediments.establishment of a site specific monitoring system.creation of well defined chemical and biological quality criteria for sediments.

"Hot spots" with high toxicity and correlating heavy metal contamination could be identified along theDanube. The identified hot spots are allocated along side arms or creeks. Sediments from the main streamare less polluted. According to the results it can be stated that the heavy metal adsorption capacity of theDanube sediments has not been "utilised" completely, meaning that the risk of the chemical time bomb inthe Danube can increase further.

ACKNOWLEDGEMENT

The present research was funded by the PHARE Technological Development and Quality ManagementProgram (Project No. H9305-02l1 11 1). Authors wish to thank Dr M. J. Wilson and Macaulay Land UseResearch Institute for making it possible to carry out the chemical measurements and analyses.

REFERENCES

Calow. P. (1993). Handbook ofEcotoxicology. Blackwell Science Ltd.Equipe Cousteau. (1993). The Danube. For Whom andfor What? Equipe Cousteau, Paris.

Heavy metal risk assessment in Danube sediments 281

EU TGD (1995). Environmental Risk Assessment ofNew and Existing Substances. EU Technical Guidance Document. Draft, May1995.

Gruiz, K. and Vodicska, M. (1993). Assessing heavy metal contamination in soil applying a bacterial biotest and X-ray fluorescentspectroscopy. In Contaminated Soil '93. F. Arendt, G. 1. Annokkee, R. Bosman and W. J. van den Brink, (cds), K1uwerAcademic. The Netherlands, pp. 1163-1164.

Gruiz, K. (1994). Bioassay to assess heavy metal contamination in soil. In Proc. Second International Symposium and Exhibitionon Environmental Contamination in Central and Eastern Europe, pp. 231-233.

Hock, B. and Uszl6, F. (1990). Contribution to the water quality evaluations of the Danube. Proceedings of the InternationalConference on Water Pollution Control in the Basin ofthe River Danube, Novi Sad. Yugoslavia, pp. 17-24.

Hungarian Standard 12749 (1994). Quality of surface water. Quality characteristics and classification: a national monitoringprogramme, with quality criteria and classification.

Hungarian Standard 21978130-1988 (1988). Investigation of hazardous waste. Microbiological test for soil.Hungarian Standard 21976117-1993 (1994). Investigation of hard waste of settlements. Seedling plant test.VITUKI (1971). Hydrogeographic Atlas. VITUKI, Budapest.VROM (1991). Environmental quality standards for soil and water. Ministerie van Volkshuisvesting, Ruimtelijke Ordening en

Milieubeheer. Leidschendam. The Netherlands.VROM (1993-94). Environmental Quality Objectives in The Netherlands. A review of environmental quality-objectives and their

policy framework in The Netherlands.WQDB (1988). Water Quality Data Base. Routine study of the quality of state-administered waters. Ministry of Transport and

Public Works (report in Dutch).