## 3 Results and Discussion
The yellow color on the transport diagrams in Figure 3 is the first site where the sample contained background concentrations of the elements in question. A closer look at the Mn concentration data (Appendix Table A1) in Transects 1 and 2 suggests that the concentrations decrease continuously from the tailings ponds out to 8.0 km. However, if a three-measurement standard deviation (3\(\sigma\), 99.7%) probability difference is required between the sample measurements, then background concentrations are reached at 4.8 km, meaning that concentrations of Mn fall to background somewhere between 3.2 km and 4.8 km. The background concentrations for Sr and Pb were identified as the point where concentrations drop to average values and required a judgment call by the authors. However, the data for Cu, Zn, As, and Mo show a clear transition from contaminated soil at the tailings ponds to background values as the distance increases. Thus, Cu, As, Sr, and Mo concentrations are at background levels at 3.2 km on Transects 1 and 2. Zinc reaches background at 3.2 km on Transect 1 and 4.8 km on Transect 2. Like Mn, Pb concentrations in soil are at background on these transects at 4.8 km, like. Thus, the transport diagrams in Figure 3 for Mn, Cu, Zn, As, Sr, Mo, and Pb show the same result, maximum transport on Transects 1 and 2 to the NE. For comparison, the wind rose diagram in the lower right hand corner (drawn from data recorded at the closest air quality monitoring station 12 km to the SW [27]), shows the velocity frequencies and directions from where the winds blow. The wind direction with the longest spoke shows that the highest frequency winds come from the SW and blow to the NE. On either side of this spoke, there are the two next-largest spokes, also showing wind directions from the SSW and WSW. This wind direction is very similar to the dispersal of TKM tailings into the environment to the NE as shown in Figure 3, and supports dispersal of particulates from the tailings ponds to the NE by the winds. On Transect 3, background concentrations of Mn, Zn, As, Sr, and Pb are reached at 1.6 km and Cu and Mo fall to background at 0.8. There are no houses on this transect. All elements fall to background concentrations by 1.6 km on Transect 4. There are no houses on this transect until 4 km. All elements fall to background by 1.6 km on Transect 5, before the first houses at 2.5 km. However, Mn goes back up slightly above background at 8.0 km. There is no explanation for this. Concentrations of Mn, Zn, As, Sr, and Mo fall to background by 1.6 km on Transect 6. Copper reaches background by 0.8 km and Pb reaches background by 3.2 km. Houses are at 1.8 km. Transport on Transect 7 is the lowest, with Mn, Cu, Zn, As, Sr, and Mo reaching background before 0.8 km, and Pb by 1.6 km. Houses begin at 1.8 km. On Transect 8 all elements reach background by 1.6 km, with houses at 2.5 km. The transport diagrams in Figure 3 are very useful and akin to wind rose diagrams. Table 1 lists the elemental concentrations in the tailings, the average background concentration, the tailings/background, the crustal abundance concentration [33], EPA's Regional Screening Levels (RSLs) and the ratio of the elemental concentration in the tailings to the RSL. The RSLs are not cleanup levels, but, when exceeded, suggest that more information is needed [8,34]. Only Mn, As, and Pb exceed the RSLs in the tailings, Mn by 85 times, As by 6000 times, and Pb by 38 times. The EPA RSLs are also exceeded for As, Pb, and Mn at 0.8 km on Transects 1, 2, 3, 4, 5, 6, and 8. Only on Transect 7 are the RSLs not exceeded at 0.8 km. At 1.6 km, only Mn, As and Pb exceed the RSL on  
Transects 1, 2, and 5. The RSL for arsenic is very low, 0.6 mg/kg, far below the XRF detection limit of 10 ppm. Thus, As could be measurable farther out on the transects with a more sensitive instrument.