Vegetative Interceptor Zones for Containment of Heavy Metal Pollutants

Principal Investigators
B.A. D. Hetrick, University of Northern Iowa; and G.M. Pierzynski, L.E. Erickson, R.S. Govindaraju and D. Sweeney, Kansas State University

Abstract

Goals: This research has two purposes. First, the efficacy of different plant and microbial regimes in reducing surface water contamination from revegetated plots will be assessed. To determine the ability of various vegetation/microbial regimes to act as buffer strips, after the first year of the project the design of the experiment will be altered. Half of the plots will remain as non-interceptor strips, while half will receive surface runoff from contaminated tailings uphill from the plots. In this way the ability of the various vegetation strips to limit heavy metal contaminated runoff can be quantified.

Rationale: In southeastern Kansas where heavy metals were mined until the middle of this century, the presence of large piles of gravel tailings with extremely high levels of cadmium, lead, and zinc pose a serious environmental and health risk which led the U.S. Environmental Protection Agency to designate this area as a Region VII Superfund Site in 1985. In areas not designated as Superfund sites, a need also exists for development of economic strategies for containment o f heavy metal contamination. While vegetation interceptor strips have been used extensively in agricultural settings to reduce surface water contamination by agricultural herbicides and pesticides, the ability of vegetation buffer strips to limit spread o f heavy metal contamination in surface water has not been studied, but could represent an economical alternative with broad application to mine spoils and areas of acid mine drainage as well.

Approach: Revegetation of Superfund and non-Supe rfund areas will be undertaken to stabilize the sites and reduce wind and water erosion from the tailings. Previous research by these investigators and that of the Bureau of Mines has suggested that certain soil microorganisms, the mycorrhizal fungi, cont ribute significantly to and may be mandatory for survival and establishment of vegetation on minespoils. Both the ability of various vegetation regimes to limit surface water erosion and spread of heavy metal contamination, and the ability of these vegetation regimes to act as interceptor strips for contamination uphill from the vegetation strips will be studied in this project.

Status: A suitable site for the field experiment has been located northwest of the city offices in Galena, Kansas , and permission to conduct experiments has been granted by the city commission. Plots have been graded and barriers erected. Cattle manure has been used as an amendment in selected plots. Six treatments with four replications have been imposed on the 24 plots. Tall fescue was the species chosen for initial seeding. Treatments are an unamended control (not seeded), an amended control (not seeded), amended and seeded, amended and seeded and will receive benomyl (a fungicide), and 2 plots that were amended, seeded and inoculated with mycorrhizae, one of which will have trees planted in spring 1996. Soil samples were collected from each plot after manure was incorporated. A mulch and nylon mesh cover has been placed over all plots. Runoff measurements will begin in spring 1996. A surface transport model is being developed, and preliminary conceptualization of the model includes surface flow, sediment transport, and solute transport components. The influence of vegetation will be explicitly represented. This project is in its first year.

Clients/Users: This research will interest those in the mining industry, regulatory community, U.S. Environmental Protection Agency, and U.S. Department of Defense.

Return to Research