Study on the geochemical properties of Fe-Mn nodule in Litang karst area

In this paper, the geochemistry properties of Fe-Mn nodule are studied in Litang karst area. Compared with corresponding soils, SiOz, Al2O3 and Fe2O3 are still the main elements in the Fe-Mn nodule. However, the Fe2O3 content increases significantly and is the most in the oxides, meanwhile the MnO content increases to some extent with the enrichment coefficients being 5.19 and 3. 40. The Fe-Mn nodule enriches heavy metal elements, the enrichment order of some heavy metals is Cr（ Ⅵ ）〉Pb〉Co〉Zn〉Ni〉Ba〉 Li. The Fe-Mn content in the soil is affected by parent rock of the soil and shallow groundwater. By correlation matrix analysis and factor analysis, it is proved that there are the nucleation and enrichment effect, the specific adsorption effect and the leaching effect.