Abstract:A comparison analysis was carried out on black carbon (BC) concentrations in Dongguang at an altitude of 30m and Maofengshan at an altitude of 550 m in the Pearl River Delta (PRD) region. The annual average concentration of BC was 5.27μg/m3 at Dongguan and 2.43μg/m3 at Maofengshan. Concentrations of BC at both sites were significantly lower than level of 8.42μg/m3 observed in Nancun station in Guangzhou, a site in the heart of the PRD area. The results show that in the rainy season, the diurnal variations at the Dongguang and Maofengshan were different as a result of influence of vertical convection. The heat-induced convection brought BC from ground to higher altitudes, lowering concentration on the ground while increasing concentration at higher latitudes. This explains that at noontime, Dongguan experienced the minimum BC concentration while BC peaked at Maofengshan. In the dry season when the synoptic weather in South China was controlled by high-pressure systems, the weak descending air had little effect in promoting vertical mixing and air dispersion was dominated by horizontal advection. Consequently, similar diurnal variations were observed at the two locations. Due to closer proximity to BC sources, the monthly variation of BC in Dongguan (standard deviation: 0.60 μg/m3) was larger than that in Maofengshan (standard deviation: 0.14 μg/m3). The value of α, which is the power index of the wavelength of BC absorption coefficient, was found to be close to 1 at both sites, indicating that BC at the two sites had fossil fuel combustion as the common source.