Identification of the effect of biomass burning on trace gases and aerosol at the remote sites of China

Abstract

The March-May months correspond to the transition from winter to summer monsoon season over Asia. As it progresses from winter to spring, convection becomes significant. Hence, pollution from Asia are mixed with the pollution from the west of China arrived with the westerly wind. At the same time, spring is the dry season in Southeast (SE) Asia. This season is favorable for the occurrence of forest fire. In addition, in late winter and early spring, people in the Asian subcontinent start to burn the crop residues of the previous year in preparation for cultivating of new crops. These fires very often become out of control. As a result, larger scale forest fires frequently occurred in Asia. My study comprised two phases. During the first phase study in spring of 2004, surface ozone (O3), carbon monoxide (CO) and aerosols over the Tibetan Plateau were measured at a remote site in the southwestern border of China. While at the second phase, surface Os and CO over the boreal forest region were measured in the same period in the spring of 2005 at a rural site in northeastern China. In the spring of 2004, surface O3, CO, and aerosols (PM2.5 and PM10) were measured within the southeastern Tibetan Plateau at Tengchong (25.01oN, 98.3 oE, 1960 m a.s.l.) in Southwest China, where observational data is scarce. The O3, level measured is low when compared with those reported in similar longitudinal sites in SE Asia as well as in northeastern Tibetan Plateau in Northwest China suggesting that there exist complex O3 variations in the Tibetan Plateau and its neighboring SE Asian region. The increase of pollutants in the lower troposphere was caused by regional built-up and transport of pollution from active biomass burning region. In the spring of 2005, ground-based measurements of O3 and CO were performed in Longfeng San World Meteorological Organization (WMO) Regional Background Station, which is located in Heilongjiang Province in northeastern China. At that time, Korean forest fires occurred. These forest fires destroyed more than 400 hectares of woodlands. Twenty one mountainous areas in Korea were engulfed. These forest fires released considerable amount of ozone precursors and particulates into the atmosphere and induced adverse effects on the regional air quality. With the help of satellite data, we found that under the influence of the low pressure system in northern China, the emissions from these forest fires traversed the Korean peninsula, and affected northeastern China. This study provided measurement data at two remote sites of China, at the Tibetan Plateau in southwestern China and at the boreal forest in northeastern China, where observational data are scarce. In this regard, the measurements from this study may serve as a baseline against which future measurements and changes are compared and evaluated. Also, the impacts of open burning activities from neighboring Asian countries to China were assessed and analyzed in this study.