Shine, JP; Ryan, DK; Ford, TE
BIOSIS COPYRIGHT: BIOL ABS. Dissolved concentrations of seven metals (As, Pb, Cd, Zn, Ni, Cu, Cr) were determined monthly at six sampling stations in Lake Chapala, Mexico, between November 1990 and December, 1991. Lake Chapala is the largest lake in Mexico, and serves as a source of drinking water and an economically important fishery and center for tourism. Historically, Lake Chapala has received poorly characterized domestic, industrial, and agricultural wastes. As, Cd, Pb, Cr, and Zn displayed peaks in concentration during the period before the rainy season due, presumably, to evaporation. Comparison of inflow and outflow concentrations also indicated a direct source of As to the lake. During this period, the concentrations of both Cd and Pb were above the freshwater chronic criteria values recommended by the United States Environmental Protection Agency for protection of aquatic ecosystem health. The metals As, Cr, Zn, Ni, and Cu also showed concentration peaks following the rainy season in Au