Temporal patterns and potential sources of polycyclic aromatic hydrocarbons in xylem of Pinus kwangtungensis

Abstract

The temporal patterns and the possible sources of polycyclic aromatic hydrocarbons (PAHs) in the xylem formed from 1883 to 2007 of Kwangtung pine (Pinus kwangtungensis), growing in the Nanling Mountains of Southern China, were detected whether dendrochemistry was sufficient to monitor historical changes in regional airborne PAHs. The total concentrations of 17 PAHs (ΣPAHs) distributed in the xylem of P. kwangtungensis did not progressively increase over time. Temporal patterns of high molecular weight PAHs (HMW–PAHs) coincided to a certain extent with the historical–socioeconomic changes in China. Based on the compositional analysis, PAHs absorbed by and accumulated in the xylem of P. kwangtungensis in the Nanling Mountains might be of pyrogenic origin. Although the possible sources of xylem PAHs were diverse over the studied period, principal component analysis could not convincingly distinguish the main contributors to xylem PAHs. Using only xylem of P. kwangtungensis was not adequate for retrospective monitoring of airborne PAHs in the atmosphere of the Nanling Mountains. Sampling other trees along a gradient and combining other meteorological and socioeconomic index data might provide more reliable information on historical changes in regional airborne PAHs.