Research on the influence of the local mining activities on the sediments quality of Baita Valley in Maramures County, Romania

摘要

Mining perimeters of Baita area are situated in northern-western of mining basin of Baia Mare, at about 17 km far from Baia Mare City. The mining perimeter geology is represented by Neogene eruptive formations. These geological deposits are characterized mainly by the presence of polymetallic mineralization of pyrite, chalcopyrite, galena, sphalerite, and sporadic the marcasite, hematite, molybdenite associated with gold and silver. The local mining activity was closed but because of the insufficient rehabilitation of the mining dumps and galleries as well as of the poor mining wastewater treatment, the environmental issues and especially the water issues persist. The investigated area has a branched hydrographic network, the main valleys being oriented NE-SW and N-S, respectively. The flowing waters are collected by the Baita Valley which has various effluents as: Rosie Valley, Lapusna Mare Valley, Lapusna Mica Valley, Trestia Valley, Galbena Valley. A major impact on the Baita Valley is caused by Galbena-Lapusna mining deposit which is near the confluence of Galbena Valley and Lapusna Mare Valley and respectively Tyuzosa mining perimeter which is near the confluence of Tyuzosa Valley and Baita Valley. At the moment there is only one wastewater treatment plant functioning, the Campurele station, which being undersized is malfunctioning. From the blending of acid water of Rosie Valley with the more alkaline water evacuated by Campurele wastewater treatment plant a precipitate results which gives a yellow-red colour to the Baita Valley water. For sediments quality assessment of Baita Valley 4 points along the valley were sampled and the sampling were analyzed for the main indicators of the mining activities: Cu, Zn, Mn, Pb, Fe, Cd si Ni and pH. These values have been compared with the maximum allowable values laid down by regulations regarding the sediments. The results have shown the exceeding of the maximum allowable limits by tens or even hundreds times especially for Cu, Zn, Mn and Pb.