Speciation of Mercury in Hg-Contaminated Soils from Oak Ridge TN

Oral Presentation

Prepared by Z. Arslan1, E. Pierce2, E. Begu1, F. Han1
1 - Jackson State University, 1400 John R Lynch St, Department of Chemistry, Physics & Atmospheric Sciences, Jackson, MS, 39217, United States
2 - Oak Ridge National Laboratory (ORNL), Environmental Sciences Division, Oak Ridge, TN, 37831, United States


Contact Information: zikri.arslan@jsums.edu; 601-979-2072


ABSTRACT

The speciation of Hg is important to understand its mobility, bioavailability in soils, sediments and biota and potential toxicity on human and environmental health. A legacy Hg Hg spill occurred in 1960s at the Oak Ridge Reservation of the Department of Energy (DOE) that contaminated facilities, soil, sediment, surface water, and groundwater within the boundaries of the Y-12 Plant Security Complex and the downstream environment along the East Fork Poplar Creek (EFPC) at the city of Oak Ridge. In this work, total elemental analyses and Hg speciation in the floodplain soils and sediments collected along EFPC in Oak Ridge, TN to determine of Hg distribution in soil fractions and the relation with metals including arsenic, copper, zinc and lead. Total elemental characterization was performed by ICP-MS analysis after with HNO3 and HF dissolution. Sequential extractions were carried out to extract water-soluble (F1), cation-exchangeable (F2) fractions and those bound to carbonates (F3), reducible oxides (F4) (Mn-oxides), organic matter (F5), amorphous (F6) and crystalline iron oxides (F7) and the residual fraction (F8) containing elemental Hg, non-cinnabar Hg and humic acid-bound Hg. Preliminary studies were conducted with artificially spiked and incubated soils as well as soils contaminated with enriched 200Hg isotope. The results indicated that Hg is predominantly associated with organic matter, amorphous iron and crystalline oxides and the residual fraction. The total Hg in the first four fractions (F1, F2, F3, and F4) were about 1% of the total Hg, while Hg was found equally bound to organic matter (F5) and crystalline Fe-oxides (F7) that accounted about 20% of total Hg. The Hg associated with amorphous iron oxides (F6) accounted as much as 26% of total Hg and non-cinnabar Hg accounted about 24% of total Hg (non-cinnabar Hg). The results also indicated positive correlation for As, Cu, Pb and Zn levels with those of Hg.