Characterization of the rivers system in the mining and industrial area of Baia Mare, Romania

The status of the river system in the mining region of Baia Mare is examined, following the long term mining activity in the area and the cyanide spill accident that occured in January 2000. The cyanide spill released more than 100,000 cubic meters of liquid and suspended waste that contained cyanide and heavy metals. Most of it, estimated at 50 to 100 tons of CN, reached the local river catchment. More than 50km of river, upstream and downstream of the cyanide spill inflow were sampled for water, sediments and aquatic ecosystem. The heavy metal content in water is within the limits of Romanian standards in most of the sampling sites. No cyanide was found in the water. The sediments have a high content of heavy metals and cyanides with minimum and maximum values in mg/kg as following, Cu: 104 – 339, Pb: 59 – 465, Zn: 56 – 2060, Cd: 0.05 – 14.14, CN: 0.33 – 15.86. These values demonstrate the potential toxicity of the sediments. The cyanide spill affected all components of the aquatic ecosystem. Some of the microalgae species with narrow tolerance to changes in water quality disappeared on Somes river. A recovery is taking place but with a smaller number of species and with cosmopolite species. The number of fish species decreased dramatically as compared with the period before the accident. The new fish individuals that were collected in the affected area are young and come from the upstream section of the rivers. It was demonstrated experimentally that many species of mollusks disappeared downstream the cyanide spill inflow mainly because their capacity to accumulate large amount of heavy metals was exceeded. © 2003 SDU. All rights reserved.