Development of River Water and Sediment Quality at Remediated Uranium Mining and Milling Legacy Sites (“WISMUT Project”) in Germany
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Development of river water and sediment quality at remediated uranium mining and milling legacy sites (“WISMUT Project”) in Germany Annia Greif, Elke Kreyßig Wismut GmbH, Jagdschänkenstraße 29, 09117 Chemnitz, Germany Phone: +49-(0)-371-8120257 E-mail: [email protected] Introduction: In the Eastern part of Germany, min- concentrations. Figure 1 illustrates the decrease of ing of metals like Ag, Pb, Zn, Sn, W, Bi and Co has uranium concentrations in the aquatic phase after been carried out since the Early Middle Ages. It was commissioning of the water treatment plants at both followed by large-scale uranium mining and milling sites. The differently coloured columns indicated the between 1946 and the German reunification in 1990, situation up- and downstream to each site. by the Soviet-German company SDAG Wismut. Since 1991, the by then federal-own company 0,070 upstream Wismut 1995: Water treatment Helmsdorf downstream Schlema Wismut GmbH has been significantly mitigated the 0,060 upstream Crossen environmental impacts of the uranium production downstream Wismut legacy sites. The WISMUT Environmental Project 0,050 was launched. Key elements were (and continue to 0,040 1999: Water treatment Schlema-Alberoda (subsystem 1) be) dismantling of industrial structures, flooding of 0,030 mines, clean-up of contaminated sites, coverage of 2001: Water treatment Schlema-Alberoda (subsystem 2) waste rock piles and safeguarding of radioactive 0,020 uranium [median] in water in [median] [mg/l] uranium tailings. The commissioning of powerful water 0,010 treatment plants in the late nineties contributed essen- 0,000 tially to the decrease of surface water and sediment- borne pollutions. The development of the environ- Fig. 1: Uranium in water of Zwickauer Mulde (da- mental parameters is reflected by results gained with- ta: Wismut GmbH) in the WISMUT Environmental Monitoring Program. Since beginning of water treatment, also investiga- Methods: Within its monitoring program, Wismut tion of the suspended sediments is part of the GmbH operates appr. 100 surface water and 18 sus- WISMUT Monitoring Program. From Figure 2 it can pended sediment investigation points. Location of the be learned, that arsenic and some other elements are points allows studying of the impact of controlled found in significant concentrations already in the discharges into rivers (e. g. from water treatment Zwickauer Mulde before the river passes the plants) as well as of diffuse discharges (e. g. as seep- WISMUT sites. This is caused by its geogenic back- age from tailings management facilities and waste ground occurrence and by other industrial activities rock dumps). The time series of monitoring data (25 outside of WISMUT. years) give answer on pollution before, during and after remediation of the objects and sites. In water, 400 upstream Wismut downstream Schlema 350 the dissolved phase as well as the total content are upstream Crossen downstream Wismut analysed. For the investigation of suspended matter, 300 250 sediment traps have been installed. Key analytical 200 parameters along the water and sediment path are 150 uranium and radium (nuclide Ra-226). In addition to [mean] arsenic 100 50 this, arsenic, iron, manganese, nickel and zinc are sediments [mg/kg] fresh in 0 site-specifically of interest. The monitoring is aimed 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 to control the parameters against water and sediment Fig. 2: Arsenic in suspended sediments (fraction quality standards set in German regulations as well as <63 µm) of Zwickauer Mulde (data: Wismut GmbH) in the EU Water Framework Directive. Conclusions: Implementation of the WISMUT Envi- Results: The Zwickauer Mulde, one of the biggest ronmental Monitoring Program has accompanied the rivers passing the WISMUT area, is affected by the significant improvement of the water and sediment sites Schlema-Alberoda (former complex mining quality in former uranium production areas in Eastern site) and Crossen (former ore processing site). Past Germany. Study of the big amount of environmental the German reunification the river section inside of data allows understanding the distribution processes the both sites offered considerably high uranium of pollutants along watercourses. .