DISTRIBUTION OF HEAVY METALS IN SOIL AROUND TAR CREEK

From the 1900s to the 1960s the land surrounding Tar Creek was part of the Picher Field of the Tri-State Mining District, one of the top Pb, Cd, and Zn producing parts of the world. This intense mining generated piles of mine tailings called chat. Surface water draining through the chat piles and groundwater exiting open mine shafts contaminated both the creek and the soil with heavy metals. My partner and I are researching how these heavy metals are distributed from Tar Creek during flood events by examining metal concentrations in soil and water along the creek. We collected water samples in northeastern Oklahoma at the Commerce 66 site of the mining district, Douthat Bridge, and Miami. We also collected water samples in Kansas at Kansas 169, upstream from the mining district. Along with water samples, we took soil cores that on average went down 11 inches along a 30 meter transect line on each side of the creek at the 4 sites, creating horizontal profiles on both sides of Tar Creek at each site. In the lab, we sampled each core at 3, 15, and 23 cm below surface, creating vertical profiles for each core site. Finally, we dried, crushed and powdered our samples for x-ray fluorescence (XRF) analysis at Oklahoma State University. The XRF data were graphed with the expectation that it would show how contamination could spread during floods and how deep the heavy metals could leach down into the soil or be deposited with sediment during flood events. We hypothesized that the closer we sampled to the main mining district, the higher metal concentration would be in the soil. We expected the highest concentrations of metals in water and soil at Douthat Bridge, decreasing levels of metals at Commerce 66 and Miami, and very low concentrations at Kansas 166. We also expected and found the soil cores in the mining district closer to the creek to have higher concentrations of heavy metals than those farther from the present channel or outside the present floodplain. Our preliminary data on the changes of concentrations vertically in soil cores show that there are more heavy metals in the shallow sections of the core compared to the deeper part of the core. This finding will be examined more by comparing metal levels to soil properties to determine if flood events deposited metal-contaminated sediment or if metals are leaching downward from flooding of the present surface.