Variation of heavy metals, magnetic susceptibility, and some chemical properties in the Lichen-rock interface on various parent rocks in west of Iran

Abstract

This investigation was directed to explore the impacts of Lecanora Ach. (1809) on magnetic susceptibility, some chemical properties, and heavy metals concentration in the interfaces with interior rocks including andesite, diorite, tuff, and hornblende-gabbro in the west of Iran. In each of the selected rocks, 15 samples of lichen-rock interfaces were excoriated and analyzed for heavy metals, some chemical analyses, and magnetic susceptibility (χ). The results showed that most of metals were reduced significantly (p < 0.05) in lichen-rock interfaces as compared to interior rocks, that mainly related to weathering and leaching of metals from the rocks and consequently related to dilution effects that cause reduction of the concentration of metals in the mass unit. Comparison of magnetic susceptibility in the lichen-rock interface with interior rocks showed that there is a significant reduction of χlf (magnetic susceptibility at low frequency) for developed soils on the rocks compared to interior rocks in all cases. This may be related to dilution of ferrimagnetic minerals in the interface by the presence of paramagnetic minerals (phyllosilicates) or diamagnetic (calcium carbonates and organic materials) in the interfaces. Lichen is grown on the various rocks showed significant differences for pH, calcium carbonate equivalent (CCE), and Fed (iron extracted by dithionite), which mainly attributed to the nature of parent rocks. The results of multiple linear regression (MLR) indicated that soil properties included total Fe, Fed, OM (organic matter) and CCE explained about 79% of the variability in χlf in lichen-rock interfaces. For further clarification of complicated processes that occurred in the interfaces between lichen and rocks regarding soil pedogenesis as well as an indicator of bio-monitoring, further investigations on the various rocks and different species of lichen are recommended.