Effects of Abandoned Lead and Zinc Mines and Tailings Piles on Water Quality in the Joplin Area,Missouri.

摘要

Dissolved zinc concentrations averaged 9,400micrograms/liter in water from abandoned lead and zinc mines,some of which discharge at the surface. Contamination of the shallow aquifer (cherty limestones) by the highly mineralized mine water is limited to the immediate mining area. The quality of water in the deep aquifer (cherty dolomites and sandstone) is generally excellent. Dissolved zinc concentrations averaged 16,000micrograms/liter in runoff from tailings areas. However,during a summer storm,runoff from a 7-acre tailings area contained maximum dissolved zinc,lead,and cadmium concentrations of 200,000; 400;and 1,400micrograms/liter,respectively. Mine-water discharges increase dissolved zinc concentrations in receiving streams from a background of about 40micrograms/liter to about 500micrograms/liter during periods of low flow. The higher concentrations are sustained during high flow by runoff from the tailings areas. Deposition of tailings on stream bottoms increases zinc concentrations in bottom material from a background of about 100micrograms/gram to about 2,500micrograms/gram and increases lead concentrations in bottom material from about 20micrograms/gram to about 450micrograms/gram.