Location: Soil Dynamics ResearchTitle: Effects of gypsum on trace metals in soils and earthworms Author
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/24/2012
Publication Date: 3/1/2014
Publication URL: http://handle.nal.usda.gov/10113/56923
Citation: Chen, L., Kost, D., Tian, Y., Guol, X., Watts, D.B., Norton, L.D., Wolkowski, R.P., Dick, W.A. 2014. Effects of gypsum on trace metals in soils and earthworms. Journal of Environmental Quality. 43:263-272. doi:10.2134/jeq2012.0096 Interpretive Summary: Mined gypsum has been used as a nutrient source for agricultural production for years. Currently, power companies are producing large of amount of gypsum as a byproduct of removing sulfur from coal burned for power production. Research has shown that power company’s gypsum (FGD gypsum) can improve crop production similar to mined gypsum. However, information is need on how heavy metals and mercury in the power company gypsum will impact the environment. Thus, power company gypsum and mined gypsum was evaluated in Ohio, Indiana, Alabama, and Wisconsin. Mercury was slightly increased in soils and earthworms with power company gypsum compare the mined gypsum and soil without gypsum, however these increases were not significant. Selenium increased in earthworms with power company gypsum compared soil with no gypsum, but was not higher than the use of mined gypsum. This study shows that use of power company gypsum at normal recommended agricultural rates will not have a significant impact on heavy metal concentrations in earthworms and soils.
Technical Abstract: Mined gypsum has been beneficially used for many years as an agricultural amendment. Currently a large amount of flue gas desulfurization (FGD) gypsum is produced by removal of SO2 from flue gas streams when fuels with high S content are burned. The FGD gypsum, similar to mined gypsum, can enhance crop production. However, information is lacking concerning the potential environmental impacts of heavy metals, especially Hg, in the FGD gypsum. FGD gypsum and mined gypsums were evaluated to determine their ability to effect concentrations of Hg and other trace elements in soils and earthworms. The study was conducted at four field sites across the United States (Ohio, Indiana, Alabama, and Wisconsin). The application rates of gypsums varied from 2.2 Mg ha-1 in Indiana to 20 Mg ha-1 in Ohio and Alabama. These rates are two to ten times higher than typically recommended. The lengths of time from gypsum application to soil and earthworm sampling were 5 and 18 months in Ohio, 6 months in Indiana, 11 months in Alabama, and 4 months in Wisconsin. Earthworm populations were decreased by both the FGD and mined gypsums in Ohio. Among all the elements examined, Hg was slightly increased in soils and earthworms in the FGD gypsum treatments compared to both the control and the mined gypsum treatments. The differences were not statistically significant except for the Hg concentration in the soil at the Wisconsin site. Se in earthworms in the FGD gypsum treatments was statistically higher than in the controls, but not higher than in the mined gypsum treatments, at Indiana and Wisconsin sites. Bioaccumulation factors were statistically similar or lower for the FGD gypsum treatments compared to the controls for all elements. Use of FGD gypsum at normal recommended agricultural rates seems not to have a significant impact on concentrations of heavy metals in earthworms and soils.