Location: National Soil Erosion Research Lab
Title: Environmental evaluation of flue gas desulfurization gypsum as a BMP for erosion control Author
Submitted to: Proceedings of the American Society of Agricultural and Biological Engineers International (ASABE)
Publication Type: Proceedings
Publication Acceptance Date: August 18, 2011
Publication Date: September 18, 2011
Citation: Norton, L.D. 2011. Environmental evaluation of flue gas desulfurization gypsum as a BMP for erosion control [abstract]. In: Proceedings of the American Society of Agricultural and Biological Engineers International (ASABE). September 18-21, 2011, Anchorage, Alaska. 2011 CD ROM. Technical Abstract: Flue Gas Desulfurization Gypsum (FGDG) is produced from pollution control systems reducing sulfur dioxide emissions from thermo-electric coal-fired power plants. Natural gypsum and FGDG both have been shown to be useful in control of soil erosion. However, concerns have been raised recently by environmental groups as to the fate of trace elements in FGDG especially that of mercury (Hg). The most common production practice of FGDG may trap some of the Hg present in the coal that normally would escape as vapor in the stack gases. Some FGDG, especially production from older facilities, may have other trace elements associated with fly ash mixing or contamination. In order to evaluate the fate of Hg and other trace elements, we conducted field studies at two locations where FGDG was compared to commercially available pelletized natural gypsum (PG) and a control. The FGDG used came from modern coal fired power plants producing high purity (wallboard quality) FGDG. The rates used were typical agronomic rates and those used for erosion control and were varied between 0 and 6.72 MT ha-1. Crops were grown in the fields using standard agricultural practices and fertility recommendations. One field experiment was conducted in 2008-2009 on a Yedo silt loam with a corn/soybean rotation near Kingman, IN and the second at the Arlington, WI field station of the University of Wisconsin with alfalfa in 2009-2010 on a Plano silt loam. In 2008, corn tissue was sampled at silk stage from the ear leaf and at harvest for total plant fodder analysis. Grain was also collected for analyses of Nitrogen (N), Carbon (C), Sulfur (S) and trace elements. In 2009, soybean tissues at flowering and alfalfa forage samples at first cutting after FGDG and PG application prior to planting were collected for the same analyses. The only significant difference in Hg content found was a slight increase in concentration for corn ear leaf samples when 2.24 MT ha-1 FGDG was applied in 2008. At harvest, neither the mature corn fodder nor grain had any significant difference in Hg or other trace element concentrations with FGDG gypsum application. Sulfur increased in alfalfa tissue in 2009 with the rate of FGDG applied but not for PG although yields did not increase. In 2010 the similar results were obtained. Although N or C contents were not statistically different, the increase in S content may be the result of higher protein content which improves nutritional quality. Other trace elements did not increase in plants with FGDG or PG application. In both field studies, we sampled the soil before and following harvest and found no increases in trace elements with application of FGDG or PG. In 2009, we conducted a rainfall simulator study at Kingman and found no significant increase in Hg loss from FGDG treated plots in runoff waters. At both sites we collected water at 60 cm depth from suction lysimeters and found no differences in concentrations for any trace elements. We did not find any detectable potential for trace element contamination in soil, plant, surface water or shallow groundwater with FGDG or PG application. Application of FGDG or PG to fields at the rates normally used for erosion control does not represent a significant risk of getting Hg or other trace elements into the food chain or pose abnormal threat of contaminating soil, runoff or shallow groundwater with trace elements.