THE FLANKS OF THE DEALUL NEGRU TAILINGS POND (FUNDU MOLDOVEI) – POLLUTION RISK FACTORS - Carpathian Journal of Earth And Environmental Sciences

The study focuses on identifying the risk factors for the environmental pollution generated bythe flanks of the tailings pond of Dealul Negru (Fundu Moldovei mine district); in this purpose, textural,mineralogical, geochemical and statistical analyses have been carried out. XRD patterns allowed toidentify two groups of minerals: primary minerals (especially chlorite, muscovite, biotite, quartz), andweathering minerals; the latter group consists of clay minerals (illite and kaolinite) and highly solublehydrated sulfates (especially gypsum and apjohnite, but also pickeringite, halotrichite, jarosite). The mainfeature of the tailings is the differences identified between the waste from the upper levels and lowerlevels of the tailings pond, as follow: (1) a larger abundance of coarse waste particles (about 12 wt%),higher abundance of soluble fraction (mean of 0.63 wt%) and higher amounts of Fe and S (majorelements), and Zn, Cu, Pb, Cd, Cr, As (toxic elements) within the waste from the upper levels; (2) anincreasing abundance of the fine and very fine waste particles (up to about 80 wt%) and higher pH (up to3.75) specific to the tailings from the lower levels of the waste deposit. On the contrary, the PrincipalComponent Analysis suggests that the key role in unfolding these geochemical patterns is rather playedby the waste cemented layers developed on the surface of the lower levels of the waste deposit. However,the upper levels are the most susceptible to trigger environmental pollution, especially through surfacerunoffs during heavy rains and wind-driven removal and transport; the upper levels also act as a source of “primary” waste for the lower levels of the waste deposit.