Impacts of Large-Scale Land-Use Change on the Uptake of Polycyclic Aromatic Hydrocarbons in the Artificial Three Northern Regions Shelter Forest Across Northern China.

Abstract

This study quantifies the influence of large-scale land-use change induced by the artificial Three-Northern Regions Shelter Forest (TNRSF) across northern China on the environmental cycling of organic chemicals. Atmospheric removal and long-term trends of two polycyclic aromatic hydrocarbon (PAH) species, phenanthrene (PHE) and benzo[a]pyrene (BaP), resulting from increasing vegetation coverage and soil organic carbon in the TNRSF over the last two decades were examined. Field sampling data and modeling result showed that the total atmospheric removal of PHE by TNRSF increased from 36.4 tons in 1990 to 76.8 tons in 2010, increasing at a rate of 5.6% yr-1, and BaP from 2.2 to 4.5 tons, increasing at a rate of 5.2% yr-1. Three model scenarios were designed to distinguish the effects of atmospheric emissions, and with and without TNRSF on the environmental fate of PAHs. Approximately 1-4% of PHE and BaP emitted in northern China were removed by the TNRSF during 1990-2010. Model simulations revealed that the TNRSF enhanced atmospheric removal of PHE by 29% and BaP by 53% compared with the simulation without the TNRSF, manifesting marked contributions of land-use change by the artificial TNRSF, the largest afforestation activity in human history, to the atmospheric removal of organic chemicals.