Toxic trace elements and organic compounds in the ambient air of Kabul, Afghanistan

To assess the ambient air quality in Kabul, we measured the contents in tree bark samples of 17 chemical elements by ICP–MS, polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) by GC–MS, polychlorinated biphenyls (PCBs) by GC–ECD and polycyclic aromatic hydrocarbons (PAHs) by HPLC. While there were rather high levels of sulfur (up to 2277 μg/g), the heavy element contents were rather low (i.e. Pb was in the range 3.12–5.00 μg/g), even though a slight peak value was recorded in the area of most intense traffic (Pb up to 13.91 μg/g). Slight traces of organohalogen compounds, i.e. PCBs and PCDD/Fs, were detected (ΣPCBs=1.184–6.318 ng/g; ΣPCDD/Fs=1.42–2.38 pg/g). Highly chlorinated congeners, i.e. OCDD/Fs and penta-, hexa- and hepta-CBs, dominated the profiles of these compounds. Only three- and four-ringed PAH compounds were detected, but at very low levels comparable with the natural background. The slightly anomalous trace element values and the profiles of PCDD/Fs and PAHs determined in the bark samples suggest a close relationship with emissions from automotive traffic and the domestic burning of wood and fossil fuels. The presence of distinct but unimportant PCB emission sources can also be inferred.