Effect of Humic Acid Fertilizer on Mercury Release from Greenhouse Soils.

The elemental mercury (Hg⁰) release characteristics from the Hg-contaminated soil applied with Humic acid fertilizer (HAF) in the greenhouse were identified. The adsorption features of mercuric ion (Hg2+) on HAF under different reaction times and pH were investigated to elucidate the influencing mechanism of HAF on soil Hg⁰ release. Besides, the microstructure of HAF loading with Hg2+ was characterized by using Fourier transform infrared spectroscopy (FTIR) and scanning electron micrograph-energy dispersive spectrometry-EDS). The results showed that with the increasing HAF dosage, soil oxidation-reduction potential (Eh), and organic matter (SOM) content, as well as the decreasing soil pH, the soil Hg⁰ release fluxes showed a decreasing tendency. The soil pH, Eh, SOM, and total Hg content are the key factors that can affect the soil Hg⁰ release fluxes. The interior air temperature, light intensity, soil moisture, and soil temperature have little impact on soil Hg⁰ release fluxes when the greenhouse soil is applied with HAF. The HAF can immobilize Hg2+ and reduce its activity by surface precipitation and specific adsorption, then affecting the soil Hg⁰ release fluxes. The results of this study provide a basis for the application of HAF to reduce soil Hg⁰ release fluxes in the greenhouse of Hg-contaminated areas. [ABSTRACT FROM AUTHOR]