In the west of Hungary, on October 4, 2010, the tailings dam broke and toxic red sludge flooded the villages of Kolontár, Devecser and Somlóvásárhely. The disaster claimed ten lives and more than 200 people were injured. Roughly 400 houses and the entire ecosystem of the Marcal River were destroyed.
A large amount of Bauxite mining waste spilled into the surrounding area. This waste contained high amounts of dangerous contaminants, such as oxides of iron, aluminum, titanium, etc., but mainly it was highly alkaline with a pH higher than 13 (as it contains residues of the sodium hydroxide extraction agent). After the application of freshly mined Leonardite, which contains natural humic acids, the pH value of the soil dropped to an acceptable 7.5 after 24 hours. Even a few days after the application, test crops were sown on the treated soil, which germinated without any major problems. In a study carried out in connection with the disaster in Hungary, the binding capacities of humic acids for some metals were determined. It is 98% for iron and lead, 95% for copper, 75% for cadmium and 70% for nickel.