Sandy soil with phosphogypsum improves hydraulic conductivity and leachate chemical properties for reclamation

Use of phosphogypsum (PG) in building anthroposols for reclamation and/or agricultural uses would require improving its undesirable properties such as low hydraulic conductivity and leaching potential. Hydraulic functions in soil have potential to impact plant growth and development where leaching of chemicals may have implications in agriculture and for aquatic life. The objective of this study was to investigate whether PG (0, 20, 40, 50, 60, 80, 100%) mixed with a sandy textured soil affected hydraulic conductivity of the resulting mix and chemical properties of the leachate from the mixes. Hydraulic conductivity of PG was lower than that of sandy soil; adding 60% sandy soil by volume to PG significantly increased hydraulic conductivity of the mix relative to pure PG. Nickel, fluoride, arsenic, cadmium, sulphate, nitrate, cobalt, thallium, manganese, selenium, and zinc concentrations in leachate from pure PG were higher than from sandy soil. This study suggests addition of at least 60% sandy soil by volume resulted in a more optimal hydraulic conductivity and reduced concentrations of leachate components of PG to meet Canadian Council of Ministers of the Environment guidelines for aquatic life and agricultural use.