## 3 Results and Discussion  
The results for all of the concentrations of the elements in the composite surface soil samples are found in Appendix Table 1. In this paper, the elements are generally listed in order of increasing atomic number or decreasing concentration. The concentration values for the tailings soil are the average values from 17 samples collected from throughout the tailings ponds. The ponds are on the N.W. edge of the mine site. Not surprisingly, nine of the elements measured have their highest values in the tailings ponds. These concentrations are, in order of decreasing concentration: Mn (153 \(\pm\) 0.01) \(\times\) 10\({}^{3}\) mg/kg or 15.3% \(\pm\) 0.1%; Fe (40.8 \(\pm\) 0.4) \(\times\) 10\({}^{3}\) mg/kg or 4.08% \(\pm\) 0.04%; Sr (18.7 \(\pm\) 0.1) \(\times\) 10\({}^{3}\) mg/kg or 1.87% \(\pm\) 0.01%; Pb (15.3 \(\pm\) 0.1) \(\times\) 10\({}^{3}\) mg/kg or 1.53% \(\pm\) 0.01%; As (3690 \(\pm\) 80) mg/kg; Zn (2050 \(\pm\) 50) mg/kg; Cu (260 \(\pm\) 40) mg/kg; Rb (120 \(\pm\) 10) mg/kg, and Mo (44 \(\pm\) 3) mg/kg). The concentration of Zr (190 \(\pm\) 30) mg/kg is lower than offsite. Five elements (Cr, Co, Ni, Se, and Hg) are below the limit of detection (LOD) of the XRF instrument. In one place, where the tailings had been washed away exposing a shelf, samples were collected to a depth of about 30 cm. Analysis showed that the concentrations of all of the elements in this vertical profile were uniform to 30 cm. Along the eight transects, going from the Three Kids Mine tailings ponds to 8.0 km, the concentrations of nine elements decrease, or level off, to what appears to be background concentrations. Manganese goes from 153,000 mg/kg to 580 mg/kg; Fe 40,800 mg/kg to 25,000 mg/kg; Cu 260 mg/kg to \(<\)50 mg/kg; Zn 2050 mg/kg to 69 mg/kg; As 3690 mg/kg to \(<\)10 mg/kg; Rb 120 mg/kg to 79 mg/kg; Sr 1,8700 mg/kg to 730 mg/kg; Mo 44 mg/kg to \(<\)5 mg/kg; and Pb 1,5300 mg/kg to 43 mg/kg. On the other hand, Zr appears to be depleted in the tailings relative to background and goes up from 190 mg/kg in the tailings to background levels of about 360 mg/kg. The presence of Sr in the tailings is most likely because it was used in calcination at the mine [24]. Figure 3 contains transport diagrams for each element of interest and shows where the concentrations reach background concentrations (in yellow). The direction and distance of transport of contaminated soil from the mine, for the elements, is along the transect lines or spokes. These diagrams could be called dispersal diagrams, since they show the distances and directions to which particles from the mine have been dispersed. For comparison, the wind rose diagram from the closest air quality monitoring station is in the lower right hand corner. It shows the velocity frequencies and directions from which the winds come from. Transect 1 goes to the NNE and intersects Lake Las Vegas property after it crosses Lake Mead Parkway, see Figure 3. There are newly graded house pads from about 0.4 km from the tailings ponds to 2.4 km, where the transect exits Lake Las Vegas property and continues to 8 km through desert land in the Lake Mead National Recreation Area (LMNRA). Transect 2 goes to the ENE and is in the LMNRA after it leaves the mine site. Transect 3 goes to the SSE and does not encounter developed land by 8.0 km. This transect crosses low mountains at the edge of the mine site and continues through mountainous terrain. Transect 4 is to the SSW and intersects occupied houses at 4.0 km. Transect 5 extends to the SW, toward downtown Henderson and encounters houses at 2.5 km. Transect 6 goes to the SSE and  
WSW toward the city of Henderson and intersects houses in Calico Ridge at 1.8 km. Transect 7 goes W toward the north edge of Henderson and intersects houses at 1.8 km in Calico Ridge. Transect 8 goes west into South Las Vegas, toward the Las Vegas strip and intersects Calico Ridge houses at 2.4 km. The McCarran International Airport is between Transactions 7 and 8 about 18 km to the west.