HEAVY METALS IN FLUVIAL SEDIMENTS OF THE PICHER MINING FIELD, NORTHEAST OKLAHOMA
The purpose of our study was to determine if concentrations in Tar Creek have changed since the mid-1980s of lead, zinc, cadmium, copper, nickel, and iron. We collected stream sediments in the same locations as the earlier USGS study and used the same techniques for sampling and lab analyses to ensure comparable data. Concentrations remain at 109-862 ppm for lead and 3500-17,000 for zinc. Heavy metal concentrations decreased in upstream sites because of drainage diversion projects constructed after 1984. Heavy metals increased in downstream sites for two possible reasons. Particle sizes may have decreased from 1983-84 to 2000 and smaller sizes generally adsorb higher concentrations. Alternatively, additional heavy metals could have been added to Tar Creek from the floodplain and tailings during large floods. Remediation efforts have met with limited success; clean-up is prohibitively expensive; residents in former mining communities may need to be relocated.