How lead and other metals travel through the rivers of southeast Missouri’s lead and zinc mining districts is the subject of a study by two UMR students who will present their findings at a Geological Society of America meeting in St. Louis.
Anne Faeth of St. Louis, a graduate student in environmental engineering and geology and geophysics, and Josh McBurnett of Belleview, Mo., a graduate student in geology and geophysics, are comparing metal levels in Missouri’s Big River in the "Old Lead Belt" region in St. Francois County to those found in Missouri’s "New Lead Belt" in Reynolds County, both in southeast Missouri.
The students found higher levels of lead in the Old Lead Belt region, even though no mining activities have been conducted there for more than two decades.
McBurnett and Faeth will present their findings at the 38th annual meeting of the North-Central Section of the Geological Society of America April 1-2 at the Millennium Hotel in St. Louis. McBurnett will present "Energy Dispersive Spectroscopy of Big River Sediments," and Faeth will present "Heavy Metal Transport Processes in the Black River of Missouri’s New Lead Belt." Their research is funded by the Environmental Protection Agency’s Center for Study of Metals in the Environment and a U.S. Geological Survey Missouri Water Resources grant.
Mining in the Old Lead Belt began in the early 1700s when "nobody knew enough to care" about the effects of mining, says Faeth. In the 1970s, investigations by the U.S. Geological Survey and the U.S. Fish and Wildlife Service revealed elevated metal contents in the Big River, says Faeth.
Mining in the New Lead Belt began in the 1960s. "By this time people were aware of this problem of leaving piles of tailings (a sandy waste material created during mining) around for them to get into the water," says Faeth. "Tailings can be found in piles taller than buildings all over the Old and New Lead Belt regions."
As part of their research, Faeth, McBurnett and undergraduate students collected water and sediment samples both above and below the mines along the rivers. They studied the samples for metal contamination and to determine how metals are transported in water.
In the Big River, McBurnett and Faeth found metal contaminants along almost the entire stretch of river downstream from where the mine tailings enter the water. Metals transport can occur in both a dissolved or sedimentary particulate form, the researchers explain. Even though the Old Lead Belt mines have been dormant for more than 25 years, lead levels are much higher than those found in the New Lead Belt region where active mining takes place, says McBurnett.
Lead in water and sediment pose a potential health hazard to humans and the aquatic ecosystem, says McBurnett. "There are signs (in the area) warning people not to consume certain types of fish from the Big River," McBurnett says. Additional hazards include the accidental consumption of lead-bearing particles, especially by young children. Boulders have been placed on top of some of the tailing piles in an attempt to contain the waste, but "this is only partially effective in that it cuts down on wind transport and erosion," says McBurnett. "Release of dissolved metals may still be of concern where rain water moves through tailings piles."
In contrast to the Big River, the West Fork of the Black River in the New Lead Belt generally has levels below the EPA action level for drinking water, says Faeth.
"Of 30 water samples collected over a year and a half, only one exceeded the EPA limit for lead, and this sample was collected during a flood event," says Faeth. "This is surprising when you consider the magnitude of mining in the region."
McBurnett says the low level is due to new containment methods. "Today, the tailings are contained in stabilized ponds, which is an effective way to manage mine waste materials," says Faeth.
Since lead occurs naturally in rivers and streams in this area, it is sometimes hard to tell whether the lead is there due to mining activities, or if it was there all along, says Faeth.
"Lead levels in water found during the current study were generally within ranges of natural background lead concentrations, as established by a 1995 U.S. Geological Survey study, although sediment lead concentrations were higher," says Faeth.
Some good does come from lead. It is necessary for the production of products such as batteries, radiation shields such as aprons used during x-rays, and television and computer screens.
UMR faculty involved in this project are Dr. Craig Adams, the John and Susan Mathes Missouri Distinguished Professor of Environmental Engineering; Dr. Cesar Mendoza, associate professor of civil, architectural and environmental engineering; and Dr. David Wronkiewicz, associate professor of geology and geophysics.