Increasing atmospheric levels of greenhouse gases, especially CO2, and their effects on global temperature have led to interest in the possibility of carbon storage in terrestrial environments. Fly ash from coal combustion may have beneficial effects on soil properties and has the potential to significantly expand terrestrial sequestration options. A large extent of global degraded lands could be used for carbon sequestration, and fly ash may play a role. The purpose of this research is to understand the effects of fly ash on the characteristics of the soil as well as on the soil’s microbial community. Soils treated with fly ash were collected from two locations, TVA paradise in Kentucky (TVA) and Jenkins Farm at Morgantown West Virginia (JF).
Results/Conclusions
The results from carbon sorption experiments showed high sorption of carbon in the soils treated with fly ash as compared to untreated soils from both TVA and JF sites. A maximum adsorption capacity was increased by 300-800 mg/kg in JF and by 100-600 mg/kg in TVA as calculated by the Langmuir isotherm equation. In addition, there was no toxicity exhibited by the fly ash from both locations as measured by the Microtox assay. Furthermore, the soil organic carbon measured by loss-on-ignition (LOI) and the TOC were 1.5 and 2 times higher in the fly ash treated soil from TVA as compared to the control, respectively. However, there were no differences in LOI and TOC values for the JF samples. The soils from TVA showed a neutral pH of 7.2, while in contrast the soils from JF had an acidic pH of ~5.0. The mercury content in soils was about half in the fly ash treated soil from JF as compared to control and slightly higher in the fly ash treated soil from TVA. Some of the differences between the sites could be explained by the time when the fly ash treatment was performed. In TVA the fly ash was added 4-5 years ago and in JF the treatment was performed 20-plus years ago. The bacterial communities are currently being analyzed by pyrosequencing analysis of the V4 region of 16S rRNA and fungal communities based on the D1/D2 region of the LSU rRNA. This relatively new pyrosequencing technique usually produced thousands sequences per sample. The addition of fly ash may thus maximize the potential for carbon sequestration and minimizes chances for toxicity when applied to degraded lands.
