Even though lead usage has declined due to environmental awareness and regulation, several human sources of lead continue to affect birds. Hunting ammunition and fishing gear are ingested by the birds, with toxic effects.
Trace elements were present at high concentrations in 32% of the primary aquifers here, and at moderate concentrations in 17%. Of particular interest are aluminum, arsenic, vanadium, boron, fluoride, chromium, lead, and molybdenum.
Estimates of known and undiscovered copper resources total nearly 60 million metric tons of copper. Iron resources in known deposits total 2200 million metric tons of ore. Twenty mineralized areas meriting further study were identified.
Iron ore containing elevated concentrations of trace metals was smelted here during 113 years of operation (1771-1883). We sampled a variety of materials nearby to determine the amount of metals such as arsenic, chromium, copper, lead, and zinc.