Radiocarbon-based impact assessment of open biomass burning on regional carbonaceous aerosols in North China

Abstract

• PM 2.5 and TSP samples collected at Yellow River Delta were analyzed for OC and EC.• OC, EC, TSP and PM 2.5 concentrations were higher in daytime than in nighttime.• Radiocarbon ( 14 C) tracer, backward trajectories, and fire counts were used for the analysis.• Agricultural waste open burning was a main contributor to summer PM 2.5 , OC and EC. a b s t r a c t a r t i c l e i n f o Samples of total suspended particulates (TSPs) and fine particulate matter (PM 2.5 ) were collected from 29th May to 1st July, 2013 at a regional background site in Bohai Rim, North China. Mass concentrations of particulate matter and carbonaceous species showed a total of 50% and 97% of the measured TSP and PM 2.5 levels exceeded the first grade national standard of China, respectively. Daily concentrations of organic carbon (OC) and elemental carbon (EC) were detected 7.3 and 2.5 μg m −3 in TSP and 5.2 and 2.0 μg m −3 in PM 2.5 , which accounted 5.8% and 2.0% of TSP while 5.6% and 2.2% for PM 2.5 , respectively. The concentrations of OC, EC, TSP and PM 2.5 were observed higher in the day time than those in the night time. The observations were associated with the emission variations from anthropogenic activities. Two merged samples representing from south and north source areas were selected for radiocarbon analysis. The radiocarbon measurements showed 74% of water-insoluble OC (WINSOC) and 59% of EC in PM 2.5 derived from biomass burning and biogenic sources when the air masses were from south region, and 63% and 48% for the air masses from north, respectively. Combined with backward trajectories and daily burned area, open burning of agricultural wastes was found to be predominating, which was confirmed by the potential source contribution function (PSCF).

Source and formation characteristics of water-soluble organic carbon in the anthropogenic-influenced Yellow River Delta, North China

“…This was ascribed to that the air masses in first period was from south source region and encountered agricultural field burning, nevertheless, winds blowing from the clear sea presumably diluted and dispersed the air pollutants, resulting in relative lower concentrations in the second period. Detailed discussion can be found in our previous study (Zong et al, 2015). The great difference of the two periods could provide vital information about the WSOC source region in YRD.…”

“…Yellow River Delta (YRD) is a regional background receptor site in the Bohai Rim, which is influenced by seasonally air pollution outflows from Beijing, Tianjin and Hebei (BTH) and Shandong, Anhui and Jiangsu province (SAJ) under the East winter and summer monsoon. The detailed information of the site has been described in our previous study (Zong et al, 2015). PM 2.5 samples were collected by a Tisch high volume sampler at a flow rate of 1.13 m 3 min À1 , from 29 May to 1 July 2013.…”

“…Organic carbon (OC) and elemental carbon (EC) were analyzed by a Desert Research Institute (DRI) Model 2001 Carbon analyzer (Atmoslytic Inc., Calabasas, CA) following the Interagency Monitoring of Protected Visual Environment (IMPROVE_A) thermal/optical reflectance (TOR) protocol (Chow et al, 2007), which has been described in detail in our pervious study (Zong et al, 2015). For the measurements of WSOC and ionic species, briefly, one punch with 47 mm diameter was cut off from quartz fiber filters, and then was subjected to Milli-Q water.…”

“…Backward trajectories, generated by the hybrid single-particle Lagrangian integrated trajectory (HYSPLIT) model, were used to assess the passing areas of air masses encountered during the sampling time Zhang et al, 2014c;Zong et al, 2015). The model was available on the National Oceanic and Atmospheric Administration Air Resource Laboratory website (www.…”

“…In the past decades, it has experienced significant urbanization, land use change, and is potentially moving towards more serious carbonaceous aerosol pollution Zong et al, 2015). For example, a well study investigated the organic carbon precipitation elaborately and showed total carbon deposition flux could be up to 3.2 g C m À2 yr À1 in North China, greatly affecting the ecosystem (Pan et al, 2010).…”