ABSTRACT
The biggest mining project of Romania, Rosia Poieni copper ore deposit in the Apuseni Mountains, started in 1979. Until now, the open pit activity resulted in 130 million tonnes of overburden and very low grade ore which were dumped outside the open pit. A natural spontaneous bacterial leaching process has been noticed in these waste dumps since the beginning of 1990. As a result, significant quantities of acid waters with copper, zinc and iron content flowing through the dumps have been collected by Aries river, which is an important element of the Romanian hydrographic network. This paper presents the global negative effects of the polluting agents, the risk if the uncontrolled leaching process gets enhanced, and a complex research program following two main aspects: stoppage or control of the natural leaching process.
