This work investigates mercury flux in soil amended by gypsum from flue gas desulphurization (FGD) units of coal-fired power plants. There are two phases of this research, including field and greenhouse studies. Previous studies indicate that FGD gypsum could increase corn yield, but may lead to more mercury uptake by corn. Recent studies have been carried out in greenhouses to investigate mercury transport in FGD gypsum treated soil. Major aspects include uptake of mercury by plants and emission of mercury into the atmosphere based on application rates of FGD gypsum. Additional aspects include rainfall, temperature, soil, and plants types. Higher FGD gypsum application rates generally led to higher mercury concentration in the soil, as well as, increased mercury emission into the atmosphere, and increased mercury levels in plants, especially roots and leaves. Soil properties and plant species also played important roles in mercury transport. In addition, it was also found that increased water and higher temperatures may contribute to mercury emission in the atmosphere. Some plants, such as tall fescue, were able to prevent mercury from atmospheric emission and infiltration within the soil. Mercury concentration in the stem of plants was found to be increased and then plateaued upon increasing FGD gypsum application. However, mercury in roots and leaves was generally increased upon increasing FGD gypsum application rates. Some mercury was likely absorbed by leaves of plants from mercury in the surrounding atmosphere.