ENVIRONMENTAL MONITORING USING SURFACE-WATER, RIVER SEDIMENTS, AND VEGETATION - A CASE-STUDY IN THE FAMATINA RANGE, LA RIOJA, NW ARGENTINA

This work discusses trace elements studied beneath the semiarid endorh eic region of the Famatina Range (La Rioja, NW Argentina). The results obtained in 27 control sites allow the determination of five distinct geochemical patterns in the Famatina Range. Pattern 1 reflects the co mposition of underlying Paleozoic and Tertiary bedrock (background lev el: water pH, 7.5-9; specific conductance, 0.2-0.7 mS cm(-1)), which i s influenced by mineralization. Pattern 2 exhibits water pH, 6; specif ic conductance, 0.7 mS cm(-1); high contents of Cu, Cd, Rb, Zn, Sn, an d Be in waters; and high contents of Cu, Cd, Zn, Pb, Cr, Sb, Ag, Be, C o, Ni, Bi, Rare Earth Elements (REE), Li, Ba, Cs, and Sr in sediments. Pattern 3 exhibits water pH, 3-4; specific conductance, 1.0 mS cm(-1) ; high contents of Pb, Co, Be, Au, As, Cr, Hg, Th, Ba, Cs, Rb, Sb, Y, Zr, REE, and Hf in waters; high contents of Cd, Zn, Mo, and As in sedi ments). Pattern 3 is also modified by the input of elements from a sou rce external to the Famatina Range. Pattern 4 exhibits water pH, 7-8; specific conductance, 1.5-2.3 mS cm(-1); high contents of B, Li, Ba, S r, and Zn in waters; high contents of Li, Cr, Sr, Ni, and Cs in sedime nts. Finally, Pattern 5 is developed on the red sandstones from De la Cuesta Formation (water pH, 8; specific conductance, 2.5-5.0 mS cm(-1) ; high contents of Sr, Mo, U, B, Li, Rb, and Hf in waters; high conten ts of B, Ba, Cs, Li, and Rb in sediments). The mobility of above-menti oned elements is mainly related to water pH changes and evaporation pr ocesses.