Abstract. Black carbon (BC) is an important atmospheric constitute as an air pollutant and as a climate forcer. To our knowledge, field measurements of BC have not been reported over the South China Sea. Observation of light absorption coefficients (σabs) and BC concentrations by Aethalometer were conducted on Yongxing Island in the South China Sea and at five continental sites in the Pearl River Delta (PRD) region, South China during the South China Sea monsoon period (rainy season, 16 May–20 June 2008) and the northeast monsoon period (dry season, 12 December 2008–8 January 2009). At the oceanic site, the daily average BC concentrations vary from 0.28 to 2.14 μg m−3 and seasonal variations of BC were small (0.67 in dry season and 0.54 μg m−3 in rainy season). Similarly, little seasonal difference was found at a background site in PRD (2.88 in dry season and 2.62 μg m−3 in rainy season). At PRD urban sites, the daily average concentration of BC ranges from 1.56 to 37.9 μg m−3, higher in the dry season (12.6 μg m−3) and lower in the rainy season (6.4 μg m−3). The observed average σabs values in rainy vs. dry seasons are 119 vs. 62 Mm−1 at the PRD urban sites, 29 vs. 26 Mm−1 at the PRD background site, and 8.4 vs. 7.2 Mm−1 at the marine site. A bi-peak pattern in diurnal BC variation was observed at all sites while this pattern is the most prominent at the urban sites. The first peak appears in the early morning rush hour and the second peak in early evening, with the evening peak more pronounced in dry season.
Radiocarbon-Based Source Apportionment of Carbonaceous Aerosols at a Regional Background Site on Hainan Island, South China
