... 2-1 , S-2, S-3 Tlaxcoapan Lagunilla 191 2 87 2-4 , S-5 Tlahualilpan Tepatepec 191 2 87 2-6 , S-7, S-8 Mixquiahuala Progreso 192 0 79 S -9 , S-10 Tepatepec Tepatepec 195 4 35S-11 Actopan Lagunilla 197 2 ... Lagunilla 197 2 27S-12, S-13 Atitalaquia Lagunilla 197 6 23S-14, S-15 Clavijero Tepatepec 197 6 23S-16, S-17 Xicudo Progreso 197 9 20 TABLE 9. 4 Range, Mean, and Standard Deviation of Soil Characteristics ... LairdCONTENTS 9. 1 Introduction 1 89 9.2 Background 190 9. 2.1 Sources of Soil Contamination 190 9. 2.2 Chelating Agents as Soil Tests for Heavy Metals 191 9. 3 Materials and Methods 193 9. 3.1 Field...