Source identification and assessment of heavy metal contamination in different plant species in the alpine ecosystems of Mt. Madra

Abstract

Heavy metals are among important environmental pollutants due to their environmental persistence, toxicity and ability to accumulate in living organisms. The aim of the present study was to investigate the levels of aluminium (Al), boron (B), cobalt (Co), chromium (Cr), copper (Cu), and molybdenum (Mo) in plants sampled from Mt. Madra, analysed their distribution characteristics and investigated their origins using Positive Matrix Factorization (PMF) modelling. The multi-point sampling technique was used to collect samples of 26 plants from Madra Mountain at altitudes ranging from 177 m to 1347 m. Inductively-coupled plasma optical emission spectroscopy (ICP-OES) was used for the determination of metals. The metal concentrations (all in terms of mg/kg) determined by ICP-OES are the following sequences (mean ± standard deviation): Al (827.97 ± 198.95) > B (38.49 ± 2.50) > Co (0.74 ± 0.15) > Cr (1.90 ± 0.39) > Cu (7.68 ± 0.73) > Mo (0.51 ± 0.06). Based on the results obtained from the plant samples with the highest concentrations, the following metals were identified: Al (Ajuga orientalis, 4643.57 mg/kg), B (Quercus petraea, 69.25 mg/kg), Co (Ajuga orientalis, 4.23 mg/kg), Cr (Teucrium lamiifolium, 8.64 mg/kg), Cu (Ajuga orientalis, 19.75 mg/kg) and Mo (Ajuga orientalis, 1.07 mg/kg). In conclusion, the results of the source identification analysis conducted by PMF indicated that metal concentrations in the alpine zone have a primarily anthropogenic origin.