292-28 Transport and Interactions of Kaolinite and Mercury In Saturated Sand Media.



Tuesday, October 18, 2011
Henry Gonzalez Convention Center, Hall C, Street Level

Yingjia Zhu, Soil and Water Science, University of Florida, Gainesville, FL, Lena Ma, Soil and Water science, Unversity of Florida, Gainesville, FL, Bin Gao, University of Florida, Gainesville, FL, Willie Harris, 106 Newell Hall, University of Florida, Gainesville, FL, J.C Bonzongo, Environmental Engineer Sciences, Unverisity of Florida, Gainesville, FL and Binhe Gu, South Florida Water Management District, West Palm Beach, FL
To evaluate the potential of Hg release and co-transport by colloids, it is important to understand how colloids and Hg-loaded colloids migrate in soils. We examined Hg sorption onto quartz sand and kaolinite colloids at 0.5-100 mg L-1 Hg via batch experiments. The transport behaviors of Hg, kaolinite, and Hg-loaded kaolinite in water-saturated sand columns were evaluated via column experiments. Hg sorption by kaolinite and sand were nonlinear and fit the Langmuir model, with the maximum Hg sorption capacity being 1.2 mg g-1 kaolinite and 0.11 mg g-1 sand. Hg transport in sand media had higher retardation (R=1.14-1.15) and lower mass recovery (87-93%) than kaolinite transport (R=1 with 96% recovery). Preloading kaolinite with Hg (0.073 and 0.43 mg g-1) reduced kaolinite’s mobility with 8.4 and 24% Hg-loaded kaolinite being retained in the column. Kaolinite at 250 mg L-1 mobilized 14% and 0.95% Hg presorbed on the sand media at 1 and 100 mg L-1 Hg. Correlation analysis revealed that desorbed Hg was significantly correlated with kaolinite (r= 0.811 and r= 0.807, P< 0.0001). Hence kaolinite enhanced Hg transport in the sand media serving both as a carrier (Hg was loaded before transport) and as mobile colloids stripping Hg off the sand media (Hg was loaded during transport).
See more from this Division: S11 Soils & Environmental Quality
See more from this Session: General Soil and Environmental Quality Posters: I