RMZ - Materials and Geoenvironment, Vol. 52, No. 1, 75-20, 2005
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Selected metals in the sediments of River Sava, Slovenia
Jože Kotnik1, Milena Horvat1, Nives Ogrinc1, Radmila Milačič1, Janez Ščančar1, Vesna Fajon1, Andrej Križanovski2
1 Jožef Stefan Institute, Department of Environmental Sciences, Jamova 39, 1000 Ljubljana, Slovenia 2 Sava Power Generation Company, Hajdrihova 2. 1000 Ljubljana, Slovenia
Abstract: In order to determine the anthropogenic contribution of selected metals (Cd, Co, Cr, Cu, Fe, Hg, Ni, Pb and Zn) to background levels, concentrations of these metals were measured in sediments at several downstream locations. An extracting procedure using 2S % (v/v) acetic acid was applied for estimation of the extent of contamination with heavy metals originating from anthropogenic activities. In addition, a normalization technique was used to determine background, naturally enriched and contamination levels. Aluminum was found to be good normalizer for most of the measured elements. The results suggest that an anthropogenic contamination of certain metal is not necessarily connected to easily extractable fraction in 2S % acetic acid. As a consequence of anthropogenic activities the elevated levels of all measured elements were found near Acroni Jesenice steelworks and at some locations downflow from biggest cities.
Key words: heavy metals, acetic acid extraction, normalization, river sediments, Slovenia
Introduction
Several studies used the normalization approach to quantify the degree of anthropogenic pollution in different water environments. Usually the Al as a major constituent of alumosilicates (Din, 1992; Tam & Yao, 1998) and Fe as a clay mineral indicator element (Morse et al., 1993; Kennicutt et al., 1994; Tam & Yao, 1998) have been used. As total metal concentration in sediment does not give adequate data about metal origin it also does not provide any data about metal solubility, mobility and potential bio-aviability in sediment. To study the bioaviability of the metals in sediment several extraction techniques with different chemical extractants in single step and/or in sequence have been developed (Houba et al., 1996; Tack & Verloo, 1996; McGrath,
1996; Quevauviller, 1997; Mainz et al., 1997; Scancar et al., 2000). Chemical partition of sediments is used also to deduce the source and pathways by which natural and anthropogenic heavy metals have entered the environment. For marine sediments a method based on the comparison of data for total metal concentration and the portion extract-able in acetic acid was suggested to asses the extent of heavy metal contamination originating from anthropogenic activities (Loring 8 Rantala, 1992; UNEP/IOC/ IAEA, 1995).
Results and discusión
In general, the highest total metal concentrations in sediments were found at Moste hydro power plant reservoir, which is influenced
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points are located within the limits of the 95 % confidence band of the regression line, except LJII and LJ2, which represent sampling locations on the Ljubljanica upstream and downstream Ljubljana waste water treatment plant. The metals that show the anthropogenic contribution (Cd, Cr, Cu, Fe, Ni, Pb, Zn) have elevated Me/Al ratio at same locations. Concentration of Cd shows natural background at locations downstream from HPP Moste while the levels in sediments at upper flow and in HPP Moste reservoir show anthropogenic contribution most probably due to local input from Acroni Jesenice steelworks. The normalization of the data showed higher Me/Al ratios for Cu and Fe only in sediments collected in HPP Moste reservoir while the Me/Al ratios for Cr, Ni, Pb and Zn show anthropogenic contribution in sediments from HPP Moste reservoir and at certain locations around Ljubljana, especially at sampling locations LJ2 and LJIO.
by effluents from Acroni Jesenice steelworks. Concentrations of metals from the Sava River upstream (sampling sites SI to S6) are low and represent their geochemical background with exception of Cd. Cd is higher in upper flow and at HPP Moste and it is probably a consequence of uncontrolled anthropogenic source in upstream region. The highest Hg concentrations (0.7 - 1.5 mg/kg) were found downstream at sampling locations V5, V6 and V7, due to effluents from Hrastnik chlor-alkali plant (TKI Hrastnik), which used "mercury cell" until year 1997 and has since changed to membrane technology.
Basically two patterns were distinguished on normalization scatter plots. Among metals where the concentration represents their natural background (Co) almost all data
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Figure I. Sampling locations in Sava River and its inflows.
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Cd was most soluble in sediment at downstream locations (LJ and V stations). The percentage of extractable Cd was 26 to 76 %, while at upstream locations Cd was strongly bound, with extractable fraction only between 2 and 8 %. The geochemical normalization of Cd to Al indicates the anthropogenic source (industrial or municipal) at upstream locations (S and M), while acetic-acid extraction shows that Cd is strongly bound at those locations. At downstream locations lower Cd concentrations were found, indicating weaker bound.
Co, Cr, Cu and Zn showed very uniform distribution of extractable fraction along Sava
River. For Ni and Pb the soluble fraction were the highest in sediments collected at HPP Moste (Ni: 40 - 47 %; Pb: 79 - 100 %) and significantly lower at up- and downstream locations (Ni: 5 - 19 %; Pb: 9- 22 %) and show the same distribution pattern as normalization to Al. The lower percentage of extract-able metal was found for Cr (2 - 21 %) followed by Cu (3 - 28 %), Co (6 - 34 %) and Zn (17 - 48 %). Extractable fraction of Cr, Cu, Co and Zn do not show the same distribution pattern as geochemical normalization. It can therefore be concluded that Ni and Pb in sediments from HPP Moste reservoir originate from anthropogenic activities, while solubility of other metals is not necessary
Figure 2. a) scatter plots Me/Al for surface sediments in Sava River. Solid lines represents regression line and dashed lines represent the 9S % confidence band and b) percentage of metals in the fraction soluble in 2S % (v/ ) acetic acid.
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connected to anthropogenic contribution of those metals to their natural background concentrations.
Conclusions
To obtain as much as possible information about elements behavior and origin in sediments the measuring of total element concentration is not enough. The geochemical normalization to element, which is abundant in certain sediment give adequate information on origin of element (i.e. natural or anthropogenic), while acetic acid extraction does not give any information on origin, but it gives some information on mobility and bioavailability of the certain element.
The results obtained from total metal (Al, Cd, Co, Cr, Cu, Fe, Hg, Ni, Pb and Zn) concentration, acetic acid extraction (25 %, v/v) and normalization to Al indicate that sediment in HPP Moste is the most polluted area
References
Din, Z.B. (1992): Use of aluminum to normalize heavy metal data from estuarine and coastal sediments of Straits of Melaka. Mar. Pollut. Bull. 24, 484-491.
Houba, V.J.G., Lexmond, Th.M., Novozamsky, I., Van der Lee, J.J. (1996): State of the art and future developments in soil analysis for bioavailability assessment. Sci. Total Environ. 178, 21.
Kennicutt, M.C., Wade, T.L., Presley, B.J., Requejo, A.G., Brookes, J.M., Denoux, G.J. (1994): Sediment contaminants in Cosco Bay, Maine: inventories, sources and potential for biological impact. Environ. Sci. Technol. 28, 1-1S.
Loring, D.H., Rantala, R.T.T. (1992): Manual for the geochemical analyses of marine sediments and suspended particulate matter. Earth Science Reviews 32, 23S-283.
in the Sava River flow by Cd, Cr, Cu, Ni, Pb and Zn. Elevated concentrations of Co, Cr, Pb and Zn were also observed at location on the Ljubljanica River just downstream Ljubljana waste water treatement plant (LJ2). At other locations the concentrations of those metals represent their natural background. The results obtained by acetic acid extraction agreed well with normalization to Al for Pb and Ni. For other analyzed metals the acetic acid soluble fractions not connected to anthropogenic activities.
Acknowledgement
The work was conducted in the framework of Program 531 "Biological and geochemical cycles" and Program 530 "Environmental Analytical Chemistry" funded by Ministry of Education, Science and Sport of the Republic of Slovenia. We acknowledge the financial support of Sava River Hydro Power Plants and EU in the framework of SARIB project for funding this work.
Mainz, I., Esnaola, V., Millan, E. (1997): Evaluation of heavy metal availability in contaminated soils by a short sequential extraction procedure. Sci. Total. Environ. 206, 2-3, 107.
McGarth, D. (1996): Application of single and sequential extraction procedures to polluted and unpolluted soils. Sci. Total Environ. 178, 37-44.
Morse, J.W., Presley, B.J., Taylor, R.J. (1993): Trace metal chemistry of Galveston Bay: water sediments and biota. Mar. Environ. Res. 36, 1-37.
Quevauviller, Ph., Rauret, G., Lopez-Sanches, J.F., Rubio, R., Ure, A., Muntau, H. (1997): Certification of trace metal extractable contents in a sediment reference material (CRM 601) following a three-step sequential extraction procedure. Sci. Total. Environ. 20S, 223-234.
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Scancar, J., Milacic, R., Horvat, M. (2000): Comparison of various digestion and extraction procedures in analysis of heavy metals in sediments. Water, Air and Soil Pollution 118, 87-99.
Tack, F.M., Verloo, M.G. (1996): Impact of single reagent extraction using NHROAc-EDTA on the solid phase distribution of metals in a contaminated dredged sediment. Sci. Total Environ. 178, 29 - 36.
Tam, N.F.Y., Yao, M.W.Y. (1998): Normalization and heavy metal contamination in mangrove sediments. Sci. Total Environ. 216, 33-39.
UNEP/IOC/IAEA (199S): Manual for the geochemi-cal analyses of marine sediments and suspended particulate matter, reference method for marine pollution studies No. 63, UNEP 199S.
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