Fate and Impacts of Priority Pollutant Metals in Coal Fly Ash–Soil–Switchgrass Plant Mesocosms

Authors

Olushola M. Awoyemi, Department of Agricultural and Environmental Sciences, College of Agriculture, Human and Natural Sciences, Tennessee State University, Nashville, TN 37209, USA
E. Kudjo Dzantor, Department of Agricultural and Environmental Sciences, College of Agriculture, Human and Natural Sciences, Tennessee State University, Nashville, TN 37209, USA

Document Type

Article

Abstract

Coal fly ash (CFA) is a coal combustion by-product containing heavy metals (HMs) that can enter and accumulate in environmental matrices. The current study assessed the fate and effects of HMs contained in CFA on Armour silt loam (ASL) soil, switchgrass plant, and leachate. Soil impact indices compared levels of HMs in the CFA-soil admixtures to control soil (without CFA). These indices include contamination factor (*C*~f~), modified degree of contamination (m*C*~d~), and pollution load index (PLI). The ratio of the levels of HMs in switchgrass root and shoot tissues to their levels in the CFA-soil admixtures were used to determine bioaccumulation factor (BAF) and enrichment factor (EF). The levels of HMs in the leachate were compared with U.S. Environmental Protection Agency (US EPA) water quality limits. Switchgrass was grown in greenhouse pots containing 0%, 7.5%, and 15% (wt/wt) CFA-soil admixtures for 90 days. Separate portions of the admixtures were inoculated with arbuscular mycorrhizal fungi (AMF) or fortified with glutathione (GSH). Representative samples of CFA-soil admixtures and plant tissues were digested in a microwave accelerated reaction system (MARS) and digests were analyzed for selected US EPA priority pollutant HMs (Cu, Zn, Cr, Cd, Pb, Ni, and As) using inductively coupled plasma optical emission spectroscopy (ICP-OES). Results showed *C*~f~ \< 3 for Cu, Zn, Cr, Cd, Pb, and Ni in all CFA-soil treatments, except for As, which had *C*~f~ \> 3. The 7.5% and 15% CFA-soil admixtures had m*C*~d~ \< 4 and m*C*~d~ \> 4, respectively, on day 0, which were further reduced by day 90, whereas PLI values in all treatments were \>1. Switchgrass showed a preferential uptake of Cu and Zn (BAF \> 1, EF \> 1) when grown in the CFA-soil admixtures, whereas the concentrations of priority metals in the leachate were within the US EPA water quality limits, except for As. The effect and fate of HMs in the CFA-soil-switchgrass mesocosms varied temporally with CFA concentrations, AMF, and GSH in the soil.

First Page

42

Last Page

51

DOI

https://doi.org/10.4177/CCGP-D-17-00004.1

Volume

9

Publication Date

1-1-2017

Recommended Citation

Awoyemi, Olushola M., and E. Kudjo Dzantor. 2017. “Fate and Impacts of Priority Pollutant Metals in Coal Fly Ash-Soil-Switchgrass Plant Mesocosms.” Coal Combustion and Gasification Products 9 (3): 42–51. https://doi.org/10.4177/CCGP-D-17-00004.1.