Preface Uranium is a radioactive element and a heavy metal which is naturally occurring in ground and surface water. Although uranium is enriched in granites and gneiss ground water from these host rocks often shows low to intermediate uranium con­ centrations, while some ground waters from sandstone and carbonate aquifers show elevated uranium concentrations up to several hundred mg/1 without man made impact. On the other side, surface water contains increased anthropogenic uranium concentrations due to the intensive use of phosphate fertilizers and in mining areas due to mining and milling activities. Saxony and Thuringia both be­ ing states of the reunified Germany are probably an area where uranium mining activities have impacted the environment more severely than in any other part of the world. Thus, the federal government of Germany allocated huge amounts of money for the rehabilitation work, a unique proceeding without precedent in min­ ing history. In October 1995 the first international conference on Uranium Mining and Hydrogeology (UMM I) was held in Freiberg being organized by the Department of Geology at the technical University Freiberg by the support of the Saxon State Ministry of Geology and Environment. Due to the large scientific interest in the topic ofuranium a second conference (UMH II) took place in Freiberg in Septem­ ber 1998.

Dose Limits and Maximum Concentration Limits (MCL's) for Radionuclides - Implication on Remediation of Uranium Mining and Milling Facilities in Saxony, Germany.- Remediation oriented use of conceptual site models at WISMUT GmbH: Rehabilitation of the Trünzig tailings management area.- Deep mine hydrogeology after closure: insights from the UK.- Strategy Concept Elbe.- Environmental hydrogeology of in situ leach uranium mining in Australia.- Reliance on existing wetlands for pollution control around the Witwatersrand gold/uranium mines of South Africa - Are they sufficient?.- Radon, water and abandoned metalliferous mines in the UK: Environmental and Human Health implications.- Physico-chemical surface water conditions of catchments with metallogenic origin: A contribution to the establishment of the EC Water Framework Directive 2000/60/EG in Germany.- Radionuclides in underground water in an area contaminated with uranium mill waste.- Impact of Uranium Mining and Processing on the Environment of Mountainous areas of Kyrgyzstan.- Uranium content in ground water in Stara Planina Triassic sediments.- Contaminant transport from proposed Jabiluka mine uranium tailings paste repositories - 10 000 year dispersion and dilution analysis.- Natural Uranium Fluxes and their Use in Repository Safety Assessment.- Long Term Safety of the Asse Salt Mine.- Risk Assessment for Underground Disposal of Radioactive Wastes in Clay Strata.- Uranium Migration in Argillaceous Sediments as Analogue for Transport Processes in the Far Field of Repositories (Heselbach Site, Germany).- Translating natural concentrations and fluxes into safety indicators for radioactive waste repositories.- Evaluation of the long-term durability of engineered dry covers for mining wastes, and consideration of associated design constraints.- Hydrology of Engineered Covers of Waste Rock Dumps towards Heavy Rainfall Phenomena: A Case Study in Uranium Mill Tailings Mitigation.- Hard pan formation on mining residuals.- Supercritical Carbon Dioxide Fluid Leaching (SFL) of Uranium from Solid Wastes Using HNO3-tributylphosphate (TBP) Complex as a Reactant.- Release behaviour of radionuclides from contaminated concrete materials.- Solubility of an uranium(IV) amorphous phase under geochemical conditions representative for the direct disposal of spent nuclear fuel in Boom Clay.- Uranium migration in argillaceous sediments as analogue for transport processes in the far field of repositories (Ruprechtov site, Czech Republic).- Groundwater flow systems and the export of uranium from nuclear waste repositories to the biosphere.- Natural U occurrences as a palaeo-hydrogeological indicator - observations from the Palmottu natural analogue site, Finland.- Calculation of radioactive field in nuclear accident contaminated area from data acquired in aerial survey.- Experimental large diameter well in the clays for radioactive waste Repository.- Redox processes in uranium deposits - Lessons from Natural Analogue Studies.- Flooding of the Königstein uranium mine - Aquifer reactivity versus dilution.- Numerical simulation of uranium transport in flooded underground mines.- Stream pollution by adjacent tailing deposits and fluvial transport of dissolved uranium - dynamics and mechanisms investigated in mining areas of Germany, Southern Africa and Australia.- Mobilities of uranium species in sedimentary interbed from the Snake River Plain.- A 3-D numerical modeling of reactive transport of U(VI) in shallow groundwaters: a case study at a uranium mill tailing site in southern China.- Flooding of the deep uranium mine Hamr I by free water from tailings pond.- Application of numerical simulation system on Turonian aquifer remediation control.- Factors controlling migration and concentration of natural and technogenic radionuclides in bottom sediments of the Eastern Gulf of Finland, Baltic Sea.- Geochemical processes related to uranium mobilisation on groundwaters in a restored uranium mine.- Uncertainties in Chemical Calculations.- The Role of Metrology and Statistics in Making Geochemical Modeling Defensible.- The Influence of Geostatistical Data on the Reliability of the Meshless Method in Transport Modeling.- Complex Formation of Uranium(IV) with Phosphate and Arsenate.- Hyphenated techniques for speciation of Uranium and other actinides.- Raman microspectrometric investigations of UO2 alteration products: Natural analogues to alpha radiolysis effects.- Sorption of Uranium(VI) onto Schwertmannite - EXAFS investigations.- Colloid-borne Uranium in Mine Waters.- Contaminant Release and Carbonate Availability of Sulphide-Bearing Waste Rock derived from Long-term Column Tests.- Separation of uranium from aqueous solution by textile bound calixarenes.- The effect of chlorite dissolution on the sorption behavior of U(VI).- Major factors of processes forming uranium ore in exogenetic epigenetic deposits of the Chu-Sarysu Province (Southern Kazakhstan).- Microbially mediated reduction and immobilization of uranium in groundwate.- Microbial Transformations of Uranium Complexed with Organic and Inorganic Ligands.- Bacterial communities in uranium mining waste piles and their interaction with heavy metals.- Phytoextraction for clean-up of low-level uranium contaminated soil evaluated.- Long-term differences in transfer and accumulation of potentially toxic trace elements and radionuclides in trees on uranium mining dumps (Erzgebirge, Germany).- Uranium and thorium uptake on hydrophilic plants.- Soil formation and quality on uranium mining dumps depending on different tree species under special consideration of selected radionuclide contamination.- Ecosystem restoration incorporating minerotrophic ecology and Stoneworts that accumulate 226Ra.- Characterization of uranium (VI) complexes formed by different bacteria relevant to uranium mining waste piles.- Uranium speciation in plants.- Mobilization of hazardous metals by plants growing in soils from uranium mining.- Mobility and plant availability of heavy metals in soils of uranium mining dumps.- Complex Formation of Uranium(VI) with Glucose 1 -Phosphate.- Performance report on the operations of a pilot plant for the treatment of vanadium in ground water-New Rifle UMTRA Site, Rifle, Colorado, USA.- Inter-disciplinary studies of the impact of gold and uranium mining in the Witwatersrand Goldfield.- Removal of uranium and arsenic from groundwater using six different reactive materials: assessment of removal efficiency.- Processes in passive mine water remediation with zero-valent iron and lignite as r…