Death in the Danube Cyanide Spills

Among chemists, major debates were irtflamed by a story on a popirlar everting news in Hungary. The journalists could not be blamed in this instance as they actually asked someone who looked like a real expert. 

As already stated, the water used in the television experiment was only similar to the Tisza water in its concentration of cyanide. The pollution, in fact, came from a gold mine. In a gold mine, metals that are above gold in the periodic table (silver and, mainly, copper) are also present. So the pollution that was ealled a cyanide spill in the press actually contained a number of additional eomponents. The presence of copper itself would have not been a problem, but its interaetion with cyanide ions fundamentally altered the ehentieal properties. Even among ehemists, heated debates followed among those who were not aware of all important facts. 

As already foretold, the presence of copper causes fundamental changes. First, it explains why HCN did not slowly evaporate from the river water. Although this process was also slowed down by the cold winter weather, it would still have been much faster if copper had not been present. Copper also forms cyano complexes very much like iron does, but they are more stable than the iron(II) complexes, and, more importantly, they are as toxic as the cyanide ion itself. A species distribution diagram which includes the presence of copper is shown in Fig. 4.28, right panel. The y axis here represents the actual state of the river at the worst time of the pollu- 

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