Compositional data analysis of heavy metal contamination and eco-environmental risks in Himalayan agricultural soils, northern Pakistan.

The importance of soil as a critical environmental medium cannot be overstated, as it provides various ecosystem services while supporting agricultural activities. Regrettably, soil contamination can impair the utility of these services and productivity in agriculture, and may even create several health hazards. Therefore, this study aimed to envisage the levels of heavy metals (HM) contamination in agricultural soils and identify the possible sources of contamination. A total of 54 soil samples from the designated area were obtained and subjected to analysis for the presence of nine HM, i.e., Ni, Cd, Cr, Co, Fe, Mn, Cu, Zn, and Pb, using atomic absorption spectrometry. This study used several single and multi-parameter indices for pollution and ecological risk evaluation. Compositional data analysis (CoDa) was used to assess the associations and potential sources of the HM. The findings revealed that Fe demonstrated the highest concentration among the studied HM, while Cd exhibited the lowest. The ecological risks were primarily attributed to Mn and Cd, with a considerable (40%) number of samples indicating high ecological risks. Based on contamination indices, Cd was identified as the study area's primary concern for soil pollution. Nevertheless, the PLI and modified degree of contamination (mCdeg) values exhibited a minimal inclusive effect of HM on soil. Furthermore, it was determined that the source of origin for all HM except Cd and Pb was geogenic. The soils in the area are under lesser human influence and mostly suggest a natural state. However, the contamination risk posed by Cd and the ecological risk posed by Cd and Mn raise concerns. A comprehensive evaluation of the contamination status and the risks was obtained using multiple indices. This study highlights the need for monitoring and managing HM contamination and mitigating the potential risks from Cd and Mn contamination in the area. • Compositional data analysis was used to assess associations and potential sources. • Fe demonstrated the highest concentration in soil, while Cd exhibited the lowest. • 40 % of samples in this study showed high ecological risks due Cd and Mn. • Based on contamination indices, Cd identified as primary concern for soil pollution. [ABSTRACT FROM AUTHOR]