Active biomonitoring of potentially toxic elements in urban air by two distinct moss species and two analytical techniques: a pan-Southeastern European study

This is the first study to use moss transplants as a biomonitoring technique and inductively plasma mass spectrometry to investigate airborne potentially toxic element pollution and air quality in urban areas on a regional scale across nine Southeastern European countries. The mosses in bags were exposed for 2 months during the winter season (2019/2020) at five sites in each of the selected urban areas next to air quality (AQ) monitoring stations. The sites were selected concerning different land use classes (typical urban, residential, urban background, and rural sites). The concentrations of 35 elements were determined using inductively coupled plasma mass spectrometry. A comparison with elemental analysis performed by total reflection X-ray fluorescence is also presented. Concentrations of the potentially toxic element in moss bags exposed in urban areas were significantly higher, while those exposed in rural areas did not differ significantly from the initial content of unexposed moss. Linear regression analysis revealed no significant differences between the average concentrations of elements in H. cupressiforme and S. girgensohnii moss bags (linearity R 2 = 0.94). It shows similar trends in elements in both moss species. The median values of contamination factors in both moss species ranged mostly from 1.2 to 2.17, indicating the exposure sites show no contamination to slight contamination status (C1 to C2 scales). High values of relative accumulation factors were found for Cr, Cu, Fe, Ni, Sb, and V in moss bags, indicating these elements are the most abundant in most sampling sites, which may increase human exposure through inhalation and could lead to harmful health problems.