北京森林BVOCs排放特征及对区域空气质量的影响

Emission characteristics of BVOCs from forests and its impact on regional air quality in Beijing were studied by analyzing the volume data of second-class forest resources survey in Beijing and investigating the BVOCs emission factors from relevant literatures. The results showed that the average BVOCs emissions from forest in Beijing were 27.97×10⁹g C/a, with a range of 9.46~76.45×10⁹g C/a. The contribution of isoprene, monoterpene and other VOCs (OVOCs) to total BVOCs emissions were 75.09%, 15.62% and 9.29%, respectively. The BVOCs emissions had significant species variation: poplar and quercus were the main species responsible for isoprene emission, contributing 63.16% and 25.92% to the total, respectively; Pinus tabulaeformis was the main species responsible for monoterpene emission, contributing 40.90% to the total. Forests of different age-class had different contributions to BVOCs emissions. Half-mature forest was the main emission source and contributed 39.14% to the total BVOCs emission from forests. The seasonal variations of BVOCs emissions were significant, and the emissions in spring, summer, autumn and winter accounted for 12.55%, 77.48%, 9.76% and 0.21% of the annual emissions, respectively. The ozone formation potential of BVOCs was 240.51×10⁹g, of which isoprene was the main contributor accounting for 92.66%. The secondary organic aerosol formation potential of BVOCs was 1.73×10⁹g, and the contributions of isoprene and monoterpene were 24.26% and 75.73%, respectively. This study indicated that BVOCs emissions form forest caused the annual atmospheric ozone concentrations to rise by 9.01μg/m³ and an increase of the annual atmospheric SOA concentrations by 0.94μg/m³. Especially, BVOCs emissions had relatively high contribution to ozone formation in summer. Therefore, the VOCs emissions capacity of species should be fully considered in urban greening, which would be conductive to improve air quality.