A geostatistical approach to compare metal accumulation pattern by lichens in plain and mountainous regions of northern and central India

Abstract

Based on the physicochemical characteristics, metals emitted from the source (both natural and anthropogenic) contributes towards spatial continuity at a regional scale. Apart from the intrinsic properties of metals, meteorological conditions and topography of the region are also known to contribute towards spatial continuity. In the present study, a comparative spatial assessment of 12 metals in lichen Phaeophyscia hispidula collected from mountains and plains of northern and north-central India was carried out with the help of the indicator kriging method. The total metal concentration varies between 25.4–429 µgg−1 and 22.8–507 µgg−1 dry weight in plains and mountains, respectively. The ‘Indicator Kriging’, a cokriging non-parametric approach has been applied to predict the total metal load (TML) probability from a regional lichen database derived from the different metals in the mountain and plain regions. Cr, Cd, Cu and Pb had higher concentrations having higher coverage area, while metals like Cd and Hg had the highest localized distribution indicating point sources. The probability values of TML are further related with topography, population density and land cover attributes to specific factors responsible for metal accumulation in the study area. Observations indicated that apart from local sources, topography, population density and land cover, also plays an essential role in the spatial behaviour of the metals, which has been verified by the bioaccumulation pattern of metals in lichen samples from the mountainous region. Among which three mountainous states of Northern India, Uttarakhand has a higher concentration of metals which may be attributed to the topography and local anthropogenic sources. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.