Investigation of soil polluted with red sludge in pot experiment and reclamation with SRC

Abstract

On the 4th October 2010, one of the largest industrial disaster occured in Hungary, which caused a large environmental pollution: approximately 1.000.000 m³ of basic red sludge spilled out. After the disaster we began to carry out field samplings with pot experiment. During our investigation we observed the effects of red sludge on soil and chosen species of trees (Acacia-Robinia pseudoacacia, White willow- Salix alba and AF-2 Poplar- Populus x euramericana AF-2). By doing so, we have carefully analysed the results of our pot experiment by taking into account the existing literature on this matter as well as data analysis methods. Once the remediation has been carried out successfully we began to observe the growth of the planted energetic trees. One of the purposes of the Hungarian Government's remediation program was to plant energy plants to exploit the contaminated farmlands. We have divided our pot experiment into two parts; the first one was focused on 'treated samples of soil' while the second one aimed at observing the 'untreated samples of soil'. That way our goal was to demonstrate the pollution effect of red sludge by analysing the distinct levels of contamination which can be tolerated by the different species of trees. During the analysis of soil samples the chemical reaction was demonstrable in the red sludge polluted soil which was significantly different from the unpolluted soil sample. In addition, the level of exchangeable Na⁺-ion content and Na⁺-saturation percentage have grown as well. We also found a thin layer of salt crystals on the surface of the soil as a consequence of water evaporation. The red sludge polluted soil quickly dried out and showed the properties of salinization.As for Government's Initiative to make use of contaminated soil, the first step was to remove the red sludge from the surface and as a second step, soil nutrients were added to damaged lands. As for our experiment the plant samples have not shown signs of lack of nutrients. By considering the tempo of growth of the selected plants in the pot experiment we can conclude that the Acacia will be the fittest tree for the afforestation of areas polluted with red sludge. Once soil remediation as well as the examination of growth conditions are concluded, species of trees being able to adapt to these conditions can be selected. As for the AF-2 poplar, we have observed that its development and capacity to generate biomass showed 7.5 tons at 0% moisture content even two years after hummus with high organic content had been removed.