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Surface sediments from the Cross River estuary were analyzed for the quantitative determination of aliphatic lipids such as n-alkanes, n-alkanones and unresolved complex mixtures (UCMs) of branched and cyclic hydrocarbons. The concentrations of the hydrocarbons, including pristane and phytane, were in the range of 0.02-16.84 mg kg-1 (mean 2.23 ± 2.25 mg kg-1 dry weight). The high standard deviations for the n-alkanes most likely reflect the variation in sediment grain size and differences in quantity and quality of organic matter source input. Carbon preference indices for the full range of n-alkanes varied from 0.81 and 4.0, indicating both biogenic and residual petroleum origins. Some samples exhibit odd-to-even carbon number predominances, indicating an input from terrestrial plant waxes and/or macrophytes, whereas even-to-odd carbon number predominances were observed for other samples and are linked to industrial and/or microbial origins. Different distributions and elution ranges of UCMs were also observed, suggesting varied levels of petroleum contamination. Utilization of the LHC/SHC (long/short) ratio, ranging from 0.21-7.49, assisted in the evaluation of dominant trends for terrestrial plant and/or macrophytederived versus phytoplankton-derived organic matter inputs; while the parameter, Paq, allowed discrimination of the origin of long-chain n-alkanes and the importance of macrophyte contributions to the river system. Series of n-alkan-2-ones ranging from C15 to C35, with concentrations between 0.10 and 5.62 mg kg-1 (mean 0.82 ± 0.44 mg kg-1 dry weight) were identified and are considered to have a common origin from direct incorporation of epicuticular plant waxes on the basis of the regularity in their CPI values (1.19-1.21, odd-to-even). Phytone is thought to be a photo-induced microbial oxidation product from incorporated phytol and/or of direct input from tropical higher plant waxes. [ABSTRACT FROM AUTHOR]

Five-stage size-segregated ambient aerosol particles were collected during January 2003 until October 2004 at one urban and one suburban site of Beijing to investigate the seasonal size distributions of aliphatic and polycyclic aromatic hydrocarbons. The concentrations of total n-alkanes ranging from C11 to C35 varied between 2.1 and 2446 ngm3, with higher values at the urban site than suburban site. A seasonal fluctuation was clearly evident, with higher concentrations occurring during the colder period. The carbon preference index (CPI) of the n-alkanes displayed the highest values in the spring and apparently decreased in winter. Furthermore, smaller size airborne particle-bound n-alkanes tend to have lower CPI values. In addition, the presence of pristane, phytane, n-alkylcyclohexanes, hopanes, and steranes, together with the major unresolved complex mixture (UCM) of branched and cyclic compounds, confirmed the contribution from fossil fuel use in ambient aerosol particles of Beijing. The concentrations of 18 unsubstituted PAHs (18-PAH) varied from 0.84883 ngm3, with the content at the urban site 1.16.6 times higher than those for the suburban site. The seasonal variation of 18-PAH concentrations was as follows winter > autumn > spring > summer. About 6788 of the PAHs were associated with particles having an aerodynamic diameter 2.0 m. PAHs concentration diagnostic ratios reflect that the major source of fine particles is from fossil fuel utilization. [ABSTRACT FROM AUTHOR]