INVESTIGATION OF TRACE-METAL CONCENTRATIONS IN CROPS AND SOILS NEAR A FOSSIL-FUEL POWER-PLANT IN MARYLAND

The objectives of this study were to compare changes in atmospheric deposition rates for water soluble Zn, Cu and Mn associated with a doubling of the generating capacity of a fossil- fuel power plant located in southern Maryland with concentrations of extractable metals in soils and in corn and soybean foliage. Three atmospheric deposition samples were collected monthly during each summer from 12 research and monitoring sites located 1.6,4.8 and 9.6 km distances from the Chalk Point Generating Station for two years before and after the June 1975 expansion of generation capacity from 660 to 1320 MW. Crop leaf samples were collected at flowering, and 0-15 cm depth soil samples were collected from research plots each May. Averaged over monitoring sites and plant operational periods, respectively, significant decreases were found in atmospheric deposition rates for Zn and Mn from pre- to post-plant expansion and with increased distances. The Cu deposition rates remained unchanged from pre- to post-expansion; however, a trend for decreased rates with distance was observed. Significant differences were found in the levels of soil extractable Zn, Cu and Mn among the 12 sites and with distance from the power plant. Also, combined over sites, significantly higher levels of extractable Zn and Mn were found during post-expansion which were attributed to general increases in soil acidity found in all soil research sites. Significant increases in foliar Cu and significant decreases in foliar Mn concentrations were found in both crops from pre- to post-expansion. Leaf Zn concentrations declined in soybeans but remained unchanged in corn after plant expansion. Leaf Mn levels were highest in both crops at 1.6 km compared to more distance sites; however, foliar Zn and Cu concentrations in both crops were similar across distances from the power plant. The increase in soil extractable Zn and Mn associated with the decreases in soil pH were typically 100X larger than the recorded decreases in water soluble Zn and Mn deposition associated with power plant expansion. The observed changes in rates of metal deposition would be expected to have only minimal effects on the metal nutrition of the crops; however, the quantities of Zn and Cu being deposited would likely prevent deficiencies from occurring on the Atlantic Coastal Plain soils. © 1990 Air and Waste Management Association.