RESUMO
On 30 January 2000, following the breach in the tailing dam of the Aurul SA Baia Mare Co., a major spill of about 100,000 m(3) of cyanide and metal-rich liquid waste was released into the river system near Baia Mare in northwest Romania. The pollutants flowed via different tributaries into the Tizsa (Tisa) river and finally through the Danube river into the Black Sea. Along the way pollutants (especially cyanides) caused rapid death of aquatic organisms and animals living close to the poisoned rivers. Following request from the governments of Romania, Hungary, and the Federal Republic of Yugoslavia, United Nations sent international mission experts to the area of accident. The Czech team of four experts took very active part in this mission. Samples of surface water collected by this team 3 weeks after the accident showed high toxicity in the rivers on the Romanian territory. Due to this impact, water from the Szamos river and a large area of the Tisza river in Hungarian territory was still medially toxic. Improvement of this situation was detected only in downstream areas of the Tisza/Tisa river. The high toxicity of surface water from the locality of the Lapos river upstream of the accident indicated the possibility of toxic pollution from other sources in the area. Aquatic sediments were highly toxic only in the Aurul reservoir and its surrounding area. Rapid decline of their toxicity indicated more limited adverse impact of the "Aurul pollution" in comparison with surface water. From ecotoxicological results it is evident that there is an urgent need to start abatement activities in the Baia Mare area because the possibility of future accidents still exists (this hypothesis was proved by further accidents on 10.3.2000 and the beginning of May 2000).
