Nonmethane hydrocarbons in the transported and local air masses at a clean remote site on Hainan Island, south China

Abstract

[1] Nonmethane hydrocarbons (NMHCs) were investigated in a clean remote tropical rain forest site of Jianfengling Natural Reserve in Hainan Island in spring, autumn and early winter of 2004. The aim was to characterize air pollution transported from east Asia and SE Asian subcontinent on this relatively undeveloped region of south China. Ethane, ethyne, isoprene and ethene are the most abundant hydrocarbons. The relative contributions of pollution transport from urban and industrial zones of east Asia and agricultural zones of SE Asia are discussed with the help of backward air trajectories. The air masses from the SE Asian biomass burning region contained higher concentrations of ethane and ethyne while air masses traveling through coastal east China contained higher concentrations of ethene and toluene in addition to ethane and ethyne. It was found that anthropogenic emissions transported from the SE and south China developed and developing regions in autumn had a higher input than biomass burning emission from SE Asia in spring. Local biogenic emission was deduced to be the major source of isoprene. Hydrocarbon concentration ratios were found to be good indicators for identification of inflow air masses from different source regions.

Implications of changing urban and rural emissions on non-methane hydrocarbons in the Pearl River Delta region of China

“…The levels of most hydrocarbons in the rural DM site were higher than most rural sites in China, such as Jianfeng Mountain in Hainan Island (Tang et al, 2007a), Lin'an in the Yangtze River Delta (Guo et al, 2004), Hok Tsui in Hong Kong, but lower than Tai O in Hong Kong, when air masses passed through the PRD urban region . The levels of toluene (6.01 ppbv) and propane (2.17 ppbv) in Tai O were much higher than those in DM (3.36 and 1.59 ppbv, respectively).…”

Impact of anthropogenic emissions and open biomass burning on regional carbonaceous aerosols in South China

“…The climate is generally dry during the winter season. Not only were the greater amounts of EC emitted from the human activities in the important habitat areas (Cao et al, 2007;Zhang et al, 2008), but also large amounts of this pollutant would be generated from the open biomass burning in Southeast Asia (Tang et al, 2007). Notable exceptions occur in other seasons between the two sampling sites with different monthly maxima.…”

“…Air samples were collected on the rooftop of a two-story building at this station. There are several hills around the sampling site with elevation above 1000 m. Anthropogenic emissions transported from the Southeast and South China, and biomass burning from Southeast Asia were probably the two major potential sources at this site (Tang et al, 2007). Fig.…”

“…Eastern and Southern China are the important source region of anthropogenic pollutants, whereas Southeast Asia is an important source region of biomass burning emissions (Streets et al, 2003). The trace gases, nonmethane hydrocarbons, and aerosols emitted from those regions not only enhanced the regional contamination levels (Wang et al, 2003;Chan et al, 2006;Tang et al, 2007), but also could rise up to the free troposphere, and transport through the western Pacific and eventually crossed the Pacific Ocean to North America (de Gouw et al, 2004). However, there is only a limited literature elucidating the impact of the anthropogenic emissions and biomass burning on the regional carbonaceous aerosol in Southeast Asia.…”

“…1) were chosen to study the carbonaceous aerosol emitted from anthropogenic activities and open biomass burning in China and Southeast Asia. According to the data of atmospheric monitoring work (Wang et al, 2003;Chan et al, 2006;Tang et al, 2007Tang et al, , 2009, the three sampling sites were subject to the alteration of winds over Asian monsoon, and the temporal and spatial variations of regional industrial emissions and biomass burning (http://maps.geog.umd. edu/products.asp).…”