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Authors requiring further information regarding Elsevier’s archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright Author's personal copy Chemical Geology 276 (2010) 104–118 Contents lists available at ScienceDirect Chemical Geology journal homepage: www.elsevier.com/locate/chemgeo Sulfate and strontium water source identification by O, S and Sr isotopes and their temporal changes (1997–2008) in the region of Freiberg, central-eastern Germany M. Tichomirowa a,⁎, C. Heidel a, M. Junghans b, F. Haubrich c, J. Matschullat a a TU Bergakademie Freiberg, Institute of Mineralogy, Brennhausgasse 14, D-09599 Freiberg, Germany b TU Bergakademie Freiberg, International Centre, Lessingstr. 45, D-09599 Freiberg, Germany c TU Dresden, Institute of Soil Science and Site Ecology, Pienner Str. 7, D-01737 Tharandt, Germany article info abstract Article history: Various waters (bulk atmospheric precipitation, groundwater, river water, flowing mine water, mine drainage Received 16 February 2010 galleries and flooding mine water) were studied in the region of Freiberg to achieve an improved understanding Received in revised form 7 June 2010 of sources and mixing processes in the hydrological cycle and to specify the main sources that determine the Accepted 10 June 2010 δ18 δ34 87 86 isotope composition of dissolved sulfate and strontium ( OSO4, SSO4 and Sr/ Sr) in river water. The Editor: J.D. Blum combined use of isotope and chemical data led to identification of three major sulfate sources: i) sulfate from groundwater, ii) sulfate from the oxidation of local ore sulfides that remained in unflooded und flooded parts after Keywords: mine decommissioning, and iii) “industrial” sulfate released from abundant waste, slag and tailing deposits left Sulfate sources behind after a long mining and industrial history of the region. The same three components (groundwater, pore Precipitation water from oxidation of residual ores and industry source) were identified by analyzing Sr isotope ratios. River However, the Sr isotopes pointed out a fourth, yet unrecognized source that contributed to water of the flooded Stable isotope tracers mine section. The data show that the isotope composition of water of the river Freiberger Mulde was mainly Acid mine drainage determined by uncontaminated groundwater diluted with atmospheric precipitation, whereas the other two Strontium end-members played only a minor role for this river water. However, for the river Triebisch the isotope compositions of dissolved sulfate and strontium record a strong impact of end-members II and III after recharging the flooding water into the river. – δ18 A twelve year monitoring (1997 2008) revealed a strong decrease of OSO4 values of water from bulk – ‰ ‰ δ34 atmospheric precipitation as of 2006 2008 (7 )comparedto1997(14 ), while SSO4 values remained constant (5‰). This isotope shift was probably caused by a lower contribution of “primary” sulfates to atmospheric precipitation in recent years. Groundwater and river water (Freiberger Mulde) also showed δ18 – ‰ δ18 decreasing OSO4 values albeit to a lower degree (by 4 5 ). A decrease of OSO4 values was again found in flowing mine water (by 5–6‰) mainly affected by end-member I (uncontaminated groundwater). The flood event in August 2002 likely washed out large parts of “older” groundwater and thus enabled the relatively large δ18 oxygen isotope decrease ( OSO4) of groundwater and river water within a few years. The previously high input from the “industrial” source (waste and slag deposits) decreased from 1997 to 2002 in some drainage galleries and flooding water that discharge their water into local rivers. This led to lower δ18Oand δ34S values of dissolved sulfates in these waters accompanied by a concentration decrease of several elements (Cl, Na and Mg). However, no further decrease of the impact of this source could be detected after the storm and flood event in August 2002. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Until 1990, this region received the highest S-deposition in Central 3 Europe with local annual mean SO2-concentrations of about 100 μg/m Central-eastern Germany, together with south-western Poland and (e.g., Zimmermann et al., 2003). Many factories and power plants in East the northern Czech Republic, belongs to the former “Black Triangle”. Germany were shut down or equipped with desulfurization and dust removal systems after the German re-unification. As a result, a major decrease of industrial SO2 emissions and a corresponding decrease of S- ⁎ Corresponding author. TU Bergakademie Freiberg, Institute of Mineralogy, Brenn- deposition were observed, especially in the vicinity of coal burning hausgasse 14, D-09599 Freiberg, Germany. Tel.: +49 3731 393528; fax: +49 3731 394060. power plants (Matschullat et al., 2000; Zimmermann et al., 2003, 2006). E-mail addresses: [email protected] (M. Tichomirowa), A similar tendency of decreasing SO emissions and concentrations [email protected] (C. Heidel), 2 [email protected] (M. Junghans), [email protected] occurred in Northern Bohemia, Czech Republic, after modernization (F. Haubrich), [email protected] (J. Matschullat). of coal burning power plants in 1996–1997 (Novák et al., 2001; 0009-2541/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.chemgeo.2010.06.004 Author's personal copy M. Tichomirowa et al. / Chemical Geology 276 (2010) 104–118 105 Bridges et al., 2002). In addition to pollution from coal burning power region the methods have been applied to identify sulfate sources in plants, the Freiberg region has an 800-year of mining and related mine waters (Haubrich and Tichomirowa, 2002; Tichomirowa et al., industries, leaving behind various legacies of these former activities. 2003; Junghans and Tichomirowa, 2009). These studies identified two Related acid mine drainage has an impact not only on mine water but main sulfate sources in mine water: i) sulfate from groundwater and also on river water, even on a larger scale. The Freiberg ore deposit ii) sulfate from sulfide oxidation. contributes 37% of the Zn and 5% of the Cd contamination of the Elbe Sr isotopes likewise characterize solute Sr sources and may River (Martin et al., 1994). The region thus deserves special attention contribute to better understand water mixing processes (e.g., Negrel to trace changes in the environment which corresponds to changing et al., 1997, 2001; Siegel et al., 2000; Petelet-Giraud et al., 2003; Singh et industrial activities. al., 2006). Heidel et al. (2007) indicated three different Sr sources in Stable isotope analyses of sulfur and oxygen have been used for mine water of the Freiberg region: i) Sr from anthropogenic sources via decades to identify and quantify sources of sulfates and related mixing groundwater transport into the mine, ii) Sr released from gangue processes (e.g., Holt and Kumar, 1991; Krouse and Grinenko, 1991; carbonates, and iii) Sr released from weathering of host rocks of gangue Krouse and Mayer, 2000; Nordstrom et al., 2007). In the Freiberg ore. Fig. 1. A. Location of Saxony and the Freiberg region in Germany. B. The Freiberg area with the location of the historical city, the river Freiberger Mulde and the tributaries Münzbach (Mb) and Halsbach (Hb), the main drainage system RSS, selected ore veins and mine adits northwest of the city of Freiberg, and the location of important waste and slag deposits. The location of atmospheric precipitation collectors (prIM and prRZ), and sample locations of groundwater (gw 1, gw 68, GW 3004, 3001, 2338, 4133 and 4080), river water (FM 1–10, Mb, Hb, T1 and T2), flowing mine water (SH 1–2), drainage galleries (GS and HU), flooding water (RZUL) and drainage water at the RSS portal are shown. The location of the RSS portal is not to scale, it is about 10 km north from sample location FM 3. Author's personal copy 106 M. Tichomirowa et al. / Chemical Geology 276 (2010) 104–118 This study provides new evidence for source identification by several smaller adits (e.g., Hauptstolln Umbruch — HU, Glücksilberstern– combining isotope studies of water (O-isotopes), dissolved sulfate (S- Stolln — GS) into the Mulde River without contact with the flooded and O-isotopes), and dissolved strontium (87Sr/86Sr) with chemical workings (Figs. 1 and 2). data. Compared with our previous investigations, a larger variety of The long-lasting mining history together with other industrial water types (atmospheric precipitation, groundwater, river water and activities left behind several industrial waste deposits, mainly located mine water) was investigated to achieve an improved understanding along the river Freiberger Mulde (Fig. 1). While local sulfide ore was of the role of different sources in the hydrological cycle in the Freiberg dominantly mined and processed, ore from other regions of the world region. The new data should help identifying the major sulfate and Sr was also used in the 20th century. Particularly a location in the southeast sources that determine the isotope composition of dissolved sulfate of the old historical city centre of Freiberg (Fig. 1,nearsamplepointsFM and strontium in river water. Finally, the new data are compared with 6 and 7) has a long history of changing industrial activities (e.g., silver, our previous results to reveal temporal changes of sulfate sources and lead and arsenic smelting, coining and lead recycling). Various mixing processes over a 12 years period (1997–2008).