History of Mining in the Southeast Missouri Lead District and Description of Mine processes, regulatory controls, environmental effects, and mine facilities in the Viburnum Trend (VT) Subdistrict
- Southeastern Missouri has the largest known concentration of galena (lead sulfide) in the world.
- Missouri is the largest lead producer in the nation and consistently ranks in the top 5 for zinc.
- Missouri also ranks in the top 10 for silver and copper (Seeger).
Numerous studies have been conducted on the mining area. The most comprehensive one was done between 197x and 1977. This study looked at air and water quality, as well as soil, geochemical, and vegetation studies. Also, remote sensing data was examined. This study did not turn up anything controversial (Seeger).
The only active mines in the Southeast Missouri Lead District are in the Viburnum Trend. (2008) Mining in the VT was spurred because the Old Lead Belt had declining reserves.
The mining and milling processes have remained essentially the same throughout the history of the VT. The mills have gone through changes to improve recovery.
The actual mining and grinding happens underground, then the ore is hoisted to the surface to go into the mills. Mine water is pumped up and held to settle in reservoirs before being released into streams. Water is used in all stages of the milling process (Seeger).
The Missouri Department of Natural Resources, Hazardous Waste Program has one Superfund site in the Viburnum Trend area- public highways used as transportation routes by trucks hauling ore mineral concentrates to smelters or shipment points. The most notable environmental effect mentioned is the unusual widespread growth of benthic bacterial/algal mats downstream from mining operations (Seeger).
Ecological Impacts of Lead Mining on Ozark Streams
Several past studies have reported algal mats and documented changes in benthic macroinvertebrate communities of streams. These changes have occurred downstream of inactive mines in the Old Lead Belt and active mines in the VT. Other studies have shown increased concentration of heavy metals in plant biomass, aquatic invertebrates, and fish in streams downstream of mining areas (Besser).
Sediments were collected during July 2002 and August 2004. Multiple collection sites were used to represent a wide range of possible mining influences (Besser).
Sediments found in several stream sites downstream of VT mining areas were toxic to amphipods by negatively affecting their survival, growth, and reproduction. It ranged over stream sediments from 90% survival to 17% in the SC2 sediment (Besser).
In the pore waters from 3 reference sediments, daphnid survival ranged from 20-80% and reproduction from 0-11 young per female. All of the VT sediments had survival and reproduction rates lower than the controls (Besser).
The results supported the hypothesis that toxicity of metals associated with sediments contributes to adverse ecological effects in streams draining the VT mining district. Upper Strother Creek was the most toxic location but survival of amphipods was also significantly reduced in West Fork Black River and Bee Fork. Pore-Water toxicity tests with daphnids showed severe toxic effects at these sites and Courtois Creek as well as Sweetwater (Besser).
Elevated metal exposure, sediment toxicity, and altered invertebrate and fish communities in several streams draining active mines indicate that current practices for mining, milling, and disposal of metal-rich ores in the VT do not eliminate risks of metal toxicity in receiving streams (Besser).
Even when levels of heavy metals do not exceed regulations, fish populations decline downstream from lead and zinc mines. Lack of fish populations can be detrimental to stream beds because the fish are no longer present to maintain the streambed. Additionally, toxic effects of mining can be found in runoff up to 14km downstream from mining sites, although not at levels above environmental regulations. Industrial runoff found in streams near mines comes from water runoff from mines as well as airborne sediments, which are prone to enter watersheds near highways off the back of trucks travelling to and from mines.
Even though tailings are in containment systems, mining still is affecting streams either by seepage, surface runoff, and/or airborne dust (Besser).
Besser, M. John. “Ecological Impacts of Lead Mining on Ozark Streams: Toxicity of Sediment and Pore Water.” Ecotoxicology and Environmental Safety 72 (2009) : 516-526. Web.
Seeger, Cheryl M. “History of Mining in the Southeast Missouri Lead District and Description of Mine processes, regulatory controls, environmental effects, and mine facilities in the Viburnum Trend Subdistrict.” Hydrologic Investigations Concerning Lead Mining Issues in Southeastern Missouri U.S. Department of the Interior & U.S. Geological Survey. Chapter 1. 2008. Web.
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