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VARIABILITY OF SOIL BACKGROUND LEVELS WITH DEPTH <br /> A frequency distribution analysis of sampling depths indicated that the data could be clustered into three horizons;each comprising <br /> roughly one-third of the data. These horizons are: 1)less than 2.5 feet,2)2.5 to 10 feet,and 3)greater than 10 feet. Based on the <br /> Kruskal-Wallis nonparametric test,all chemicals except cyanide,fluoride,and silver,showed significant differences(5%level)in <br /> background levels across the vertical horizons. Therefore,separate background concentrations by depth were derived for all analytes. <br /> There is no consistent pattern relating concentrations and depth. For example,lead concentrations decrease markedly with depth,iron <br /> concentrations increase with depth,and thallium concentrations are constant. <br /> SOIL BACKGROUND LEVELS FOR<2.5 FEET <br /> Analyte n Percentile(mglkg Detection Median Method Number Number <br /> 50th 95th 99th Detection Limit Boreholes AF Bases <br /> Numnum 182 807 2 2 100% 10.3 1470 9 <br /> Antimony 201 NO 1 2 11% 6.2 1618 9 <br /> Arsenic 1 2.31 11 21. 64% 0.54 1453 9 <br /> Barium 1931 87. 990/ 1 1512 9 <br /> Beryllium 1 0. 1 5.81 559% 0.2 1515 8 <br /> Boron 7 4. 1 12. 789% 3.15 67 2 <br /> Cadmium 2 ND 8. 259/6 0.5 1678 9 <br /> Chloride 16 7. 47 142CI 91% 0.2 146 2 <br /> Chromium 224 14. 5 1 979/6 1 1773 9 <br /> Chromium6 AD 1 16% 0.2 385 8 <br /> Cobalt 176 6. 88% 1 1365 9 <br /> Copper 207 14 1868( <br /> 1 97% 2 1649 9 <br /> Cyanide 311 ND 0. 2% 0.51 297 7 <br /> Fluoride 9 0.9 F., 0.5 91 3 <br /> Iron 1 1 34 99'io 5.4 1516 9 <br /> Lead 225 6.1 47 77% 1.7 1732 10 <br /> Magnesium 175 3 176001 990/ 12.3 1418 9 <br /> Manganese 189 24 1504 999/6 1 1505 9 <br /> Mercury 1 ND 1 0. 14% 0.1 1301 9 <br /> Molybdenum 169 NO 21 21% 2 1326 7 <br /> Nickel 1991 8.2 31 78. 71% 4 1591 9 <br /> Selenium 1941 ND 11 8% 0.66 1485 9 <br /> Silver 2154 ND 11. 9% 1 1723 9 <br /> ff7inc <br /> 144 171 1124431 81% 52.0 1178 8 <br /> 194 ND 2 17 6% 6.5 ism 9 <br /> 189 30. 131 98°/ 1 1478 9 <br /> 219 4 18 62 98% 2 1777 9 <br /> SOIL BACKGROUND LEVELS FOR 2.5 FEET TO 10 FEET <br /> EA-In Percentile r k< Detection Median Method Number Number <br /> 50th 95th 99th Detection Limit Boreholes AF Bases <br /> 1259 9150 242(10 31100 100% 11 929 9 <br /> 1510 3.4 13 30 11% 6.6 1194 91395 2.6 14.7 45.9 72"/0 0.54 98.5 9 <br /> 1330 97 383 655 99% 1 957 9 <br /> Beryllium 1397 0.3 1.1 10.3 59% 0.2 1084 8 <br /> Boron 70 40.4 139 141 97% 3.4 52 3 <br /> Cadmium 1519 ADI Z2 5.2 180/ 0.5 1210 9 <br /> Chloride 100 6.7 517 2625 931/6 0.2 88 2 <br /> Chrorritrn 1712 12 48 9Z5 961/6 1 1288 9 <br /> Chromumr6 409 0.3 Z5 7.5 161/6 0.2 296 8 <br /> Cobalt 1179 7.2 22 36.7 890/ 1 866 9 <br /> Copper 1 1614 11 56.1 167 96% 2 1191 9 <br /> Cyanide 251 AD AD 1.6 20/ 0.57 201 6 <br /> Fluoride 54 11 5.7 57 789% 0.5 49 1 <br /> Iron 1328 15000 368DO 49300 99% 5.7 <br /> Lead 1732 2.9 22 71.6 61% 2.1 1 <br /> Magnesium 1227 4320 10900 21800 99% 20.3 695 9 <br /> Manganese 1318 278 786 1500 99'/0 1 962 9 <br /> Mercury 1136 AD 0.3 0.3 10% 0.1 871 9 <br /> Molybdenum 1119 AD 20 26 16% 2 844 <br /> Nckel 1602 7.4 39.1 59.8 690/ 4 1190EM <br /> Selenium 1352 AD 11.5 50 8% 0.6 981 <br /> Shyer 1595 AD 2 5 7% 1 1232 <br /> Sodium 1090 270 2410 5180 90% 52 800 <br /> Thallium 1465 AD 25.o000D4 166 7% 6.5 1147 <br /> Vinadum 1317 34 92 130 99% 1 945 <br /> Znc 1717 35.1 100 270 98% 2 1281 <br />