Modelling human choices: MADeM and decision‑making

Research supported by FAPESP 2015/50122-0 and DFG-GRTK 1740/2. RP and AR are also part of the Research, Innovation and Dissemination Center for Neuromathematics FAPESP grant (2013/07699-0). RP is supported by a FAPESP scholarship (2013/25667-8). ACR is partially supported by a CNPq fellowship (grant 306251/2014-0)

Hydrogeochemistry of groundwater seepage into an acidic mining lake

In the Lusatian Lignite Mining District 259 mining lakes (ML) are originating from abandoned mines. They show significant differences in their morphometry and are mostly strong acidic (HEMM et al. 2002). The oxidation of sedimentary pyrite in aerated dump sediments (tertiary sands) forms acid mine drainage rich in iron and sulphate which is still present after filling the pit and has decisive influence on matter flux, biocoenotic development and possible uses, e.g. recreation or water supply (UHLMANN et al. 2001).Mining lakes are groundwater dominated hydrological systems (HOFMANN et al. 2004). During the last three decades the approach of seepage meters was mainly established in shelf regions of oceans, estuaries or lakes to quantify groundwater flux (LEE 1977, BOYLE 1994, BURNETT et al. 2002). But only a few usages of seepage meters are known from acidic mining lakes (BOZAU et al. 2000, WEBER 2000).The main purpose of this study was to investigate the interaction of acid mine drainage with the sediment by using seepage meters. Therefore, ML Plessa 117 was chosen as a typical example of mining lakes in geological, hydrogeological and hydrological devastated areas

Potential for remediation of acidic mining lakes evaluated by hydrogeochemical modelling: Case study Grünewalder Lauch (Plessa 117, Lusatia/Germany)

AbstractAbout one third of several hundred mining lakes in Eastern Germany are highly acidified, and there is a need to restore them to neutral conditions because they constitute an environmental hazard for water resources and downstream environments. The aim of this study is to evaluate the efficiency of three different acid pit lake water remediation treatments: dilution with alkaline (river) water, limestone treatment and biological neutralization by organic carbon-driven alkalinity generation. The efficiency is evaluated for the acidic mining lake Grünewalder Lauch by adjusting input values into a geochemical model and making future projections. Current approaches, such as flooding with neutral surface water or extensive liming, are not suitable for many lakes because of a limited supply of alkaline water or high lime immobilizing potential of Fe- and Al-rich water in acidic lakes, respectively. Further treatment methods are, therefore, designed to combine water supply and biological measures with the management of water quality by the application of in-lake microbial processes. These processes are focused on the metabolic response of aquatic ecosystems to nutrient enrichment (enhancement of primary production and thereby organic carbon supply) and the microbial decomposition of organic matter and their effects on the gain or loss of alkalinity.The results and comparisons of different neutralization measures will be generalized by the application of hydrogeochemical models for alkalinity production showinga)the long term efficiency of the measures, depending on carbon turnover at the sediment/water interface,b)the development of bicarbonate buffering capacity as a consequence of biological measures,c)the importance of pyrite formation instead of FeS

Mining lakes as groundwater dominated hydrological systems : assessment of the water balance of Lake Plessa 117 (Lusatia, Germany) using stable isotopes

In the present study, the stable isotopes δ18 O and δ2 H were used for assessment of the water balance in a heterogeneously structured catchment area in the Lusatian Lignite Mining District, in particular, for estimation of the annual groundwater inflow and outflow (IGW and OGW) of Mining Lake Plessa 117. The application of stable isotopes was possible since the water exchange in the catchment area had reached steady-state conditions after the abandonment of mining activities in 1968 and the filling of the voids and aquifers by re-rising groundwater in the years thereafter. Diverging slopes of the Evaporation Line and the Global Meteoric Water Line manifested as evaporation from the lake catchment area. The calculated isotope water balance was compared to the commonly used surface water balance, which is unable to differentiate between IGW and OGW, and to a local groundwater model. The groundwater model calculated an IGW of about 811,000 m3 yr-1 and an OGW close to zero, whereas the isotope water balance showed fluxes of about 914,000 and 140,000 m3 yr-1, respectively. Considering the contribution of the groundwater inflow to the total annual input into the lake (∆IT) and the mean residence time (τ), where the groundwater model and the isotope water balance calculated 42 and 47% for ∆IT and 4.3 and 3.9 years for τ, respectively, it was shown that both water balance calculation methods led to comparable results despite the differences in IGW and OGW.publishe