Results of the clean-up operation to reduce pollution on flooded agricultural fields after the red mud spill in Hungary

Abstract

In Hungary, the dam of a red mud reservoir breached shortly after noon on October 4, 2010. Approximately 0.7-1 million m(3) highly alkaline red mud with very low dry matter content flowed into the Torna Creek and the surrounding area, covering 1017 ha of agricultural land. Results of the risk assessment of the accident indicated that the red mud should be removed from the surface of fields where it formed a continuous layer of more than 5 cm. After the removal, samples were taken manually from depths of 0.0-0.2 m and 0.2-0.4 m in a sampling grid and background samples unaffected by red mud from the depth of 0.0-0.3 m. Total element contents (Ag, As, Ba, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Sn, Zn, and Na) and pH values were measured, and the results were analysed using correlation analysis and the Kruskal-Wallis probe. Dependence of the measured variables from elevation above sea level was studied using a 10 m by 10 m digital elevation model. Only ∼6.5% of the flooded area was temporarily designated as unsuitable for the production of food and fodder crops. In summary, the clean-up operation can be said to have been a success.

Investigating the relationship between the prey composition of Barn Owls (Tyto alba) and the habitat structure of their hunting range in the Marcal Basin (Hungary), based on pellet analysis

“…The proportion of small mammals preferring open habitats was the highest in Apácatorna, although the proportion of open habitats within the assumed hunting range was the smallest there. Apacatorna is one of the settlements affected by red mud disaster in 2010, where the highly alkaline, heavy metal contaminated flood ran through the stream Torna (Uzinger et al 2015, Mayes et al 2016. The effects of the disaster cannot be evaluated because of the absence of previous small mammal surveys.…”

Advances in Understanding Environmental Risks of Red Mud After the Ajka Spill, Hungary

“…The low-lying agricultural lands in the region of 800-1020 ha on the floodplains of the Torna Stream and Marcal River were impacted by the spill, alongside up to 120 km of river channel where the red mud was also deposited [9,10]. Solid-phase analyses of the red mud showed it to be having a high Na content (5.8 % as Na 2 O) [16].…”

“…The recovery of red mud from affected fields (where a continuous [5 cm depth was apparent) has been shown to be vindicated by the various laboratory studies modeling the [20,21]. Systematic field sampling of affected floodplain soils after red mud removal has shown that no major residual signal of the inundation could be identified [9]. Measurements of pH, along with various key red mud indicators (Na and trace metals such as As, Co, Cr, and Mo), showed that less than 7 % of the flooded area had concentrations of metals that breached guidelines for the production of food and fodder crops, suggesting minimal leaching/mixing between red mud and the underlying arable soils before recovery works [9].…”

“…Systematic field sampling of affected floodplain soils after red mud removal has shown that no major residual signal of the inundation could be identified [9]. Measurements of pH, along with various key red mud indicators (Na and trace metals such as As, Co, Cr, and Mo), showed that less than 7 % of the flooded area had concentrations of metals that breached guidelines for the production of food and fodder crops, suggesting minimal leaching/mixing between red mud and the underlying arable soils before recovery works [9]. Even in the affected areas, the effective development of short-rotation coppice plantations for biofuel crops has been demonstrated by researchers in the years after the spill [44].…”

“…Longer-term measures included channel dredging, the recovery of red mud from affected floodplain areas, and the plowing of red mud into topsoil in areas of shallow (\50 mm) deposits to minimize fugitive dust generation [7,8]. The latter was based on a three-tiered risk assessment [8] for assessing potential ecological and public health impacts, along with risks of secondary salinization of soils [9]. In the years since the disaster, a range of studies have assessed the immediate and longer-term impacts of the spill on a suite of environmental receptors, as well as considered opportunities for the valorization of both Ajka red mud and the recovered spill material (a mixture of red mud and topsoil).…”