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The land influenced by mining activities in the European Union has been estimated to be up to 0.6%, compared to a worldwide average of 0.2%. Remediation of areas with heavy metal contamination resulting from mining activities thus represents a strategic target for European policies. Exploitation of ores and minerals often results in the degradation of the surrounding environment, exposing and liberating metals and sulphides, creating acid mine drainage which remains a long-term problem with high costs for the communities. Contamination in mining areas is characterised by the abundance of highly toxic quantities of heavy metals.


There is, however, an additional but not widely recognised problem of long-distance (10s – 100s km) dispersion of sediment associated heavy metals by fluvial processes that result in widespread and chronic pollution of floodplain soils downstream of past and present mining areas (Macklin et al., 2006 and references therein). Metal levels in affected floodplains can approach, and in some cases exceed, those found at mining sites, and in many historically mined areas of Europe these soils are used for farming with significantly elevated metal levels only being recognised after chemical testing to establish the cause of poor crop growth. Contaminated floodplain soils are also important sources of secondary pollution when river bank erosion results in the re-introduction and re-cycling of contaminating metals into river channels. In terms of the environmental legacy of mining and scale of floodplain contamination, river catchments affected directly by historical metal mining in northern England alone cover an area of 12,000 km2 (Macklin et al., 2002), which is 100-1000 times larger than the area of mining sites themselves. This is why one of the principal aims of this project is for the first time to develop remediation strategies and modelling at the catchment/landscape scale. These are urgently required in the light of predicted increases in flooding related to climate change that will accelerate the rate at which contaminated floodplain soils are remobilised.


The implementation of environmental policies for the management of contaminated areas is a complex problem for both scientific and socio-economic reasons and requires scientifically based decision support (Rodrigues et al. 2009). Risk assessment is part of the decision support system for the management of contaminated sites (Carlon et al. 2004). The hazard of contaminated areas is defined in the context of risk assessment. The key points are: (1) hazard is associated to the mobility of metals, (2) because mobility covers many scales, the hazard is at multi-scales; (3) exposure refers to the availability of metals for the target system; (4) risk is associated to the potential interception by the target system (about the coupling between mobility analyses and receptors analyses); (5) elements relevant for exposure analysis can result from mobility analysis because the mobility of metals at large scale and in food-chains depends on organisms; (6) the control of the hazard is the control of the mobility of metals at all scales. In the current risk assessment view, only the local scale (contamination site) is considered relevant, although there is ample evidence for the existence of hot-spots at greater distance.


The hazard associated to tailing ponds in Romania. The existence of several failures of tailing ponds with transboundary consequences in the recent past, and the intensive public discussions raised by large scale mining projects made the problem of hazard assessment of mining areas and in particular of tailing ponds to receive a special attention recently from the governmental authorities in Romania (Mara 2010). The inventory of mining wastes allowed the identification of 1749 tailing dumps: 1661 mining waste deposits and 73 tailing ponds. From all tailing ponds and mining waste deposits some are active, some are in conservation, while others are in "greening" state. The largest number and density of tailings and dumps can be found in Eastern Carpathians and in Apuseni Mountains. The Apuseni Mountains are drained by transboundary rivers, so in their case the management of mining areas has international relevance. Fratilescu (2011) realized dam failure safety matrixes for all the tailing ponds in Romania, classifying them in three categories: high risk, medium risk and reduced risk for dam failure. He reported 2 tailing ponds with reduced risk, 33 with medium risk and 59 with high risk for dam failure. A classification of tailing ponds regarding their heavy metal pollution hasn't been realized so far, but the environmental studies show that for all these objectives in Romania show leakages which facilitate the migration of the heavy metals into the surrounding environment (water, soil, plants). Spreading of pollution is favored also by the faulty location of these tailing ponds, where the local geology facilitates fluid migrations.


For the moment there is no governmentally accepted procedure in Romania for the integrated risk assessment of mining areas at local and catchment scale. The recent national strategy for the management of contaminated sites focused only on the local risks associated to industrially contaminated areas (Iordache et al. 2010a). Since the Baia-Mare spill that lead to cross-border contamination, several Romanian and foreign experts worked under the geomorphologic paradigm (Macklin et al. 2005) for the evaluation of current and future risks associated to mining areas, with results published in the international literature. The main problem with the geomorphologic approach proposed by Macklin et al. (2006) is that, for operational reasons, its focus is on the concentrations of metals and regulated threshold values.


1.2.1 Scientific and technical barriers that will be lifted by carrying out the project.


Stocks of metals in mining wastes. Classic methods involve extensive sampling and many lab analyses. Geochemical and mineralogical analyses are laboratory methods that cannot be improved for a considerable growth of efficiency. Deep drills (10-50 m) are expensive and need to be kept at a minimum. Geophysical methods have been used for the monitoring of tailing ponds for safety purposes (Sjodahl et al. 2005). A recent article point out the use of resistivity assessment for finding the location of sulfide-bound metals in tailing ponds (Placencia-Gomez 2010) in order to predict the potential of acid-mine drainage production. According to our knowledge there is not an integrated geophysical – geochemical – mineralogical methodology for the cost-effective assessment of the stocks of metals and their forms in tailing ponds.



Native species for remediation of mining wastes. Classic method of tailing ponds remediation involve usually covering with a thick soil layer and planting nonlocal plants, which in many cases leads on the long term to undesirable results, when the plant root system reaches the contaminated substrate (e.g. drying of the trees, review for Australia cases by Mudd 2000).  As a result of the low rate of success there is a recent trend in developing more ecologically based methods (Turnau et al. 2010 for a review), including the use of native species (Cao et al. 2009). Using native species allows for the minimization of risks for biological invasion, as many tailing ponds are located near Natura 2000 sites (mountainous areas).


Field experiments on tailing dams. Knowledge about the heterogeneity of tailing surface with respect to parameters relevant for plants is crucial in order to devise an efficient remediation solution all over the surface of the tailing material (Neushutz 2009). Lab experiments with tailing substrate should be performed before the field experiment (Sudova et al. 2008). Microorganisms developing in the rhyzosphere of the plants growing natively on the tailing surface (Carrasco et al. 2010) can function as aninoculum in the design of phytoremediation solutions (Haferburg and Kothe 2009). A major bottleneck here is to find the right combination of plants, fungi, bacteria appropriate for the tailing materials and local climatic condition specific to each tailing dam.


Models for downscaling the concentrations of toxic elements in groundwater and contaminated sediments transported from mining areas. Evaluating the effects at distance of the original or remediated tailing pond involves modelling the fluxes of metals exported by hydrological fluxes. A major bottleneck is that existing models predict the contamination of soil and groundwater at a scale not giving account for the small scale heterogeneity of contamination in soil and groundwater. This heterogeneity is crucial for predicting the risk at field crop and groundwater well level relevant for each private stakeholder downstream mining areas. Very often countryside people are not aware of the contamination on their lands and have not the resources for detailed chemical investigations of soil, crops and groundwater. Downscaling models dealing with this problem are completely innovative and environmental services for risk assessment using such models are absent, although at stake there is a major social problem. Coupled with existing transport models the innovative downscaling models will allow a quantification of the effects of metals export from mining areas at a resolution relevant for individual private stakeholder downstream. This is a base for an explicit integration of the management plans of mining sites with those of natural resources located at distance from such sites, based on a quantification of positive and negative externalities associated to the remediation measures put into practice in mining areas, or their absence.


1.2.2 Contribution by the partners to the state of the art


TIMMAR builds on knowledge gained in the Marie-Curie Host Development project Miracle (2002-2005, EVK1-CT-2001-56001, post-doc of the project leader), Umbrella (2009-2012 FP7-ENV-2008-1 no. 226870) work package for plants coordinated by the project leader), and several projects funded by the Romanian agencies (e.g. www.mecoter.cesec.ro ). The institutional partners are part of the informal National Consortium for the Biogeochemistry of Trace Elements which implemented an infrastructure project (www.infrabim.cesec.ro ) and several partnerships project in Romanian mining areas. Several publications of the members of the consortium are mentioned in the references list.


Based on our previous work we introduced a new concept of hazard assessment (Jianu et al. 2012). We differentiate between hazards with different time scales. Short term hazard of a contaminated area exists when the stocks of metals are small and the intensity of metals’ export is high. Management of the short term hazard implies rapid and operational measures. Long term hazard depends on the stock of metals and on the dynamics of internal and external conditions. A site with long term hazard may also have a short term one if the intensity of the exports is large. What is specific and usually not covered by the regulations is the case of a small hazard in the short term which may change if the time is long enough due to the large stock of metals. In such examples, the retention time of metals at the current export fluxes is a key variable in modeling the hazard on the long term and devising the management strategies of the contaminated areas. In a true contaminated basin the local situations are of multiple types thus requiring short term measures organized under a long term strategy in order to control the consequences of the hazard.


The short term hazard of a contaminated area and its future hazards in different environmental scenarios depend on the stocks of metals, on the fluxes of out-going elements, and on the retention time of the elements (ratio between stock and sum of fluxes). The types of fluxes directly relevant for this discussion are those driven by wind and by water. The hydrological fluxes can be manifested at surface (runoff) or underground (by groundwater). There are two variables influencing the intensity of the fluxes: the intensity of the carrier flux (hydrological, atmospheric), and the mobilization of metals by the carrier flux. The table below summarizes the hazard potential possibilities. The analyses of long term hazard can relocate a contaminated site from one hazard situation to another because of changes in the intensity of the carrier flux or/and of the mobility of metals. Mineralogical variables can play a role in both of these potential long term changes.


Table 1 Matrix of situations for short term hazard of a contaminated area (Jianu et al. 2012).



Mobilization of metals by the carrier flux



Large

Small

Intensity of the carrier flux

Large

Situation H1: large hazard

Situation H2a: average hazard

Small

Situation H2b: average hazard

Situation H3: small hazard

We investigated the potential of geophysical methods for characterizing the stocks and forms of metals in mining wastes and contaminated soils (in two previous partnershisp projects, www.fitorisc.cesec.ro , www.pecotox.cesec.ro; due to the crises these projects had a strong funding cut which blocked their finalisation). The sites investigated have been in Zlatna area, Romania (Ampoi and Geoagiu catchments), and included one tailing dam. Preliminary results have been published (Orza et al. 2010, Iacob et al. 2011, Jianu et al. 2012 - chapter 3.6 available at http://www.cesec.ro/pdf/Jianu_etal_2012.pdf). We explored the use of native species in the remediation of contaminated areas, by studying a population of four smal catchment in the Zlatna and Ampoi area (Iordache et al. 2010b, http://ser.semico.be/ser-pdf/EA_SER2010_313.pdf). With one of these species we performed a field experiment on tailing dam with promising results (Neagoe et al. 2011). The experiment was destroyed after one year as a result of a classic remediation project by lack of communication with the government agency responsible for tailing dams (in TIMMAR we have the support letter from this agency for the very beginning). We have demonstrated (Iordache et al 2012) that in a catchment with relatively low mining and processing activity like Ampoi river large distance hot spots of contamination were formed at distance in the vicinity of densely populated areas. A concept model for the integrated modeling of of plant and transport processes was published in Iordache et al. (2012), based on an extensive review published earlier (Iordache et al. 2009).