Measurement of PCNs in sediments collected from reservoir and river in northern Taiwan.

Sediment samples were collected from a large reservoir and a river in northern Taiwan to investigate the occurrence and characteristics of Σ73PCNs analyzed. Results indicate that total concentrations of PCNs (Di- to Octa-CNs) measured in sediments collected in reservoir (29.2 ±â€¯7.11 pg/g-dw) are significantly lower than that of samples collected in river (987 ±â€¯440 pg/g-dw). The increasing trend of PCN concentration from upstream to downstream is found for the sediments collected in reservoir. PCN concentrations measured in surface sediments are relatively higher than that measured in sub-surface sediments collected in reservoir. Tetra-CNs consistently dominate in reservoir sediments, however, Penta-, Tetra- and Mono-CNs dominate in sediments collected at different sampling sites of the river investigated, suggesting that various sources contribute to PCNs collected from river. Indeed, diagnostic ratios indicate that mix-source contribute to PCNs measured in sediments collected from the reservoir and river in northern Taiwan.

Characteristics of atmospheric polychlorinated naphthalenes (PCNs) collected at different sites in northern Taiwan.

Ambient air samples were collected simultaneously at three sites in northern Taiwan using high-volume samplers during winter and summer to evaluate the atmospheric PCN characteristics including concentration, distribution, potential sources and gas/particle partitioning. The average concentration (Σ73 PCNs from di-to octa-CN) observed at industrial site is the highest (172 ±â€¯111 pg m-3), while PCN levels measured at urban and rural sites are comparable (45.2 ±â€¯8.20 and 45.9 ±â€¯24.4 pg m-3, respectively). The PCN concentrations are higher in summer compared with those measured in winter for all three sampling sites. Gas-phase PCNs predominate in ambient air, accounting for 94 ±â€¯6.0% of total concentration. Homologue distributions of PCNs measured at industrial site are different from two other sites for both gas and particulate phases, suggesting that different sources contribute to PCNs collected at industrial site. Based on the ratios of characteristic PCN congeners and fraction of Σcombustion-related PCNs/ΣPCNs, thermal processes are identified as major sources of PCNs at industrial site. PCNs collected at urban and rural sites are mixed sources of thermal emissions and evaporation, however, more influence of thermal sources in winter and more impact of evaporation sources in summer are observed. Results of the logKp-logPL relationship indicate that both adsorption and absorption govern gas/particle partitioning of atmospheric PCNs in northern Taiwan. Furthermore, the relationship between logKp and logKOA reveals that absorption is more important in governing gas/particle partitioning of PCNs in winter compared to summer.