Spatial Distribution of Trace and Major Elements in the Hilly Soils of Lesser Himalayan Muzaffarabad, Pakistan

Muzaffarabad is geologically located in the fragile ecosystem of the Lesser Himalayan region of Pakistan. The soils of the Himalayas are under constant threat because of increase in urbanization. The study was aimed to assess the fertility status of the soils and then to estimate the environmental risk associated with elevated levels of environmentally toxic trace elements. The data obtained were incorporated on soil series map using geospatial tools (GS-9, kriging, Geographic Information Systems-Remote Sensing). Twelve soil profiles representative of soil series overlain by red Murree shales, dolomitic limestone, and schists overlain by shales interbedded with sandstone were collected in triplicate and investigated for Ca, Fe, K, Mg, Na (easily mobile elements), Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn (biologically and environmentally toxic trace elements) through acid digestion and aqua regia extraction techniques and analyzed using the atomic absorption spectrometer. Semivariograms showed that the best fit model for Cd, Co, Zn, and Pb was spherical, exponential, and Gaussian. The results of this study show that the Cd and Co contents in all soils irrespective of parent materials and geographical location remained greater than reported values for these elements for world soils but was found to be within the range of contamination threshold value. However, Cu, Pb, and Zn in soils derived from schists underlain by shales interbedded with sandstone that occupy most of the west-southern and central parts were less than the average value for world soils. This suggests that these elements were present at low concentrations naturally. Unlike schists soils, soils overlain by shales and limestone located near highways, landfill sites, and mining sites showed greater contents of Cu, Pb, and Zn than the reported value for world soils but were within the contamination threshold level. Data suggested significant enrichment with Cd and moderate enrichment for Co, Cr, Cu, Ni, Pb, and Zn in any of the soils. This suggests that the main source of trace elements in soils is parent material, whereas increase in urbanization poses a significant impact on the distribution of some of the environmentally toxic trace elements.