Continuous measurements of aerosol number size distribution in the range of 3 nm-10 mu m were performed in Pearl River Delta (PRD), China. These measurements were made during the period of 3 October to 5 November in 2004 at rural/coastal site, Xinken (22 degrees 37'N, 113 degrees 35'E, 6m above sea level), in the south suburb of Guangzhou City (22 degrees 37'N, 113 degrees 35'E, 6m abovesea level), using a Twin Differential Mobility Particle Sizer (TDMPS) combined with an Aerodynamic Particle Sizer (APS). The aerosol particles at Xinken were divided into four groups according to the observation results: nucleation mode particles (3-30 nm), Aitken mode particles (30-130 nm), accumulation mode particles (130-1000 nm) and coarse mode particles (1-10 mu m). Concentrations of nucleation mode, Aitken mode and accumulation mode particles were observed in the same order of magnitude (about 10,000 cm(-3)), among which the concentration of Aitken mode particle was the highest. The Aitken mode particles usually had two peaks: the morning peak may be caused by the land-sea circulation, which is proven to be important for transporting aged aerosols back to the sampling site, while the noon peak was ascribed to the condensational growth of new particles. New particle formation events were found on 7 days of 27 days, the new particle growth rates ranged from 2.2 to 19.8 nm h(-1) and the formation rates ranged from 0.5 to 5.2 cm(-3) s(-1), both of them were in the range of typical observed formation rates (0.01-10 cm(-3) s(-1)) and typical particle growth rates (1-20 nm h(-1)). The sustained growth of the new particles for several hours under steady northeast wind indicated that the new particle formation events may occur in a large homogeneous air mass. (c) 2008 Elsevier Ltd. All rights reserved.
Previous research in the Taihu Lake Region (TLR) of China found high levels of atmospheric organochlorine pesticides (OCPs). To understand the sources and the environmental behaviors of these OCPs in the TLR, research on air-water gas exchange was performed in 2004. Hexachlorocyclohexanes (HCHs), DDT related compounds (DDTs), cis-chlordane (CC), trans-chlordane (TC), heptachlor (HEPT), and alpha-endosulfan in both air and water samples were analyzed, and air-water gas exchange fluxes of these compounds were calculated. The net volatilization flux of alpha-HCH was 58 ng m(-2) day(-1), suggesting that the residue of technical HCH in the lake sediment might have been an important source of alpha-HCH to the air of this region after the ban of technical HCH two decades ago. The main components of technical chlordane, TC, CC, and HEPT, each had net volatilization fluxes > 230 ng m(-2) day(-1), suggesting that waste discharge from manufacturing plants in the upper region was the main source of chlordane to the lake. Unlike alpha-HCH and chlordane, o,p'-DDT and alpha-endosulfan had net deposition fluxes, suggesting that these compounds were transported through the atmosphere from land sources and then deposited into the lake. The correlation between air concentrations and ambient air temperature indicated that the current sources of o,p'-DDT and alpha-endosulfan were from land; alpha-HCH and chlordane were mainly from the lake.
Concentration and source rate of precursor vapors participating in particle formation and subsequent growth were investigated during the Pearl River Delta intensive campaign (PRD2004, October 2004) in southeastern China. Four new particle formation event days and a typical non-event day were selected for our analysis. Atmospheric sulphuric acid, the important precursor vapor in nucleation and growth, were simulated with a pseudo steady-state model based on the measurements of SO2, NOx, O-3; CO, non-methane hydrocarbon (NMHC) and ambient particle number concentrations as well as modeled photolysis frequencies obtained from measurements. The maximum midday sulphuric acid concentrations vary from 4.53 x 10(7) to 2.17 x 10(8) molecules cm(-3), the corresponding source rate via reaction of OH and SO2 range between 2.37 x 10(6) and 1.16 x 10(7) molecules cm(-3) s(-1). Nucleation mode growth rate was derived from size spectral evolution during the events to be 6:8-13.8 nm h(-1). Based on the growth rate, concentration of the vapors participating in subsequent growth were estimated to vary from 1.32 x 10(8) to 2.80 x 10(8) molecules cm(-3) with corresponding source rate between 7.26 x 10(6) and 1.64 x 10(7) molecules cm(-3) s(-1). Our results show the degree of pollution is larger in PRD. Sulphuric acid concentrations are fairly high and have a close correlation with new particle formation events. Budget analysis shows that sulphuric acid alone is not enough for required growth; other nonvolatile vapors are needed. However, sulphuric acid plays an important role in growth; the contribution of sulphuric acid to growth in PRD is 12.4%-65.2%.
This study was to explore a bibliometric approach to quantitatively assessing current research trends on atmospheric aerosol, using the related literature in the Science Citation Index (SCI) database from 1991 to 2006. Articles were concentrated on the analysis by scientific output, research performances by individuals, institutes and countries, and trends by the frequency of keywords used. Over the years, there had been a notably growth trend in research outputs, along with more participation and collaboration of institutes and countries. Research collaborative papers shifted from national inter-institutional to international collaboration. The decreasing share of world total and independent articles by the seven major industrialized countries (G7) was examined. Aerosol research in environmental and chemical related fields other than in medical fields was the mainstream of current years. Finally, author keywords, words in title and keywords plus were analyzed contrastively, with research trends and recent hotspots provided.