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The study has investigated the annual variation of the dry and wet depositions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) among different kinds of areas. A commercial suburban area, an industrial urban area, a coastal rural area and an agricultural rural area were chosen to measure the PCDD/F depositions in each season. The mean TEQ concentration, dry deposition flux and wet deposition in the industrial urban area all had the highest values, at 0.0958 pg I-TEQ/Nm 3 , 29.1 pg I-TEQ/m 2 -d and 47.8 pg/L, respectively. Additionally, the annual total deposition flux of PCDD/Fs in the commercial, industrial, coastal and agricultural areas was 168, 310, 135 and 115 ng/m 2 -year, respectively. The seasonal change of PCDD/Fs in air could be affected by heating and temperature inversion in winter or photodegradation and OH radical reaction in summer. The various homologue profiles of PCDD/Fs probably affect the distribution in environmental sinks, such as sediments or the living organisms in rivers or seas. Additionally, the results of statistical analysis indicated that PCDD I-TEQ dry deposition flux (ng I-TEQ/m 2 -month) was negatively correlated with the ambient temperature (r = -0.843) for the agricultural rural area, possibly due to vapor pressure (temperature-dependent) effect on the gas/particle PCDD/F partitioning. Furthermore, the PCDD/F concentration of wet deposition flux (ng I-TEQ/m 2 -month) was positively correlated with the monthly rainfall (r = 0.826-0.988) at the four sampling areas.

Dry deposition is one of the major routes by which air pollutants enter the ecosystem, and thus this study investigated the dry deposition characteristics of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and biphenyls (PCBs) in the ambient air of industrial, urban, and rural areas in southern Taiwan from November 2010 to May 2011. Average dry deposition fluxes of total PCDD/Fs and PCBs in the ambient air of four sites were 157-544 pg/m 2 -day (8.30-27.5 pg I-TEQ/m 2 -day) and 289-1010 pg/m 2 -day (0.540-1.94 pg WHO-TEQ/m 2 -day), respectively. The results showed that particle phase depositions dominated the dry deposition processes for the removal of PCDD/Fs and PCBs from the atmosphere, and the atmospheric deposition flux in the cold season tended to be higher than that during the warm season. The dry deposition velocity of individual PCDD/Fs (0.031-0.546 cm/s) increased as the number of chlorinated substitutes increased, which were similar to those measured or predicted in other Asian countries. Similar patterns of dry deposition velocities were observed for individual PCBs (0.069-3.38 cm/s), due to the fact that low chlorinated PCBs are predominant in gas phase and have lower deposition velocities.

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Nitrogen-doped activated carbons with high surface areas obtained from resorcinol and formaldehyde resins were evaluated as CO 2 adsorbents in a simulated flue gas stream under anhydrous and humid conditions. These carbons were prepared using two approaches, namely ammonia treatment without nitric acid pre-oxidation and amination after preoxidation. The pre-oxidation of activated carbons considerably enhanced the nitrogen incorporation during the amination process. The amination temperature affects the content and type of nitrogen incorporated onto the carbon surface, as determined by X-ray photoelectron spectroscopy, which enhances the specific adsorbent-adsorbate interaction for CO 2 in humid conditions. The presence of H 2 O in the feed gas significantly decreased CO 2 adsorption for a very low nitrogen content of virgin activated carbon. A sample prepared via the amination of pre-oxidized carbon at 700°C (NORF700) exhibited excellent tolerance to moisture and the highest CO 2 capacity of 2.10 mmol/g in a 7% CO 2 /83% N 2 /10% H 2 O wet stream at 50°C and 130 kPa. The high performance of NORF700 was ascribed to its high surface area, adequate micropore volume, and high amounts of pyrindinic-like and pyrrole-like nitrogen species. The results indicate that nitric acid preoxidation followed by ammonia treatment at 700°C is an appropriate process for preparing adsorbents for CO 2 separation in post-combustion applications.

This study investigated the concentrations and congener profiles of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in intake source water (source water) and tap drinking water (tap water) of drinking water treatment plants (DWTPs). In order to have a better understanding on the influence of atmospheric PCDD/F deposition on drinking water, PCDD/Fs in the ambient air of a DWTP (DWTP-LN) were measured and both dry and wet deposition on the water treatment facilities were assessed. The results of this study indicated that the mean PCDD/F concentration in tap water (0.0039 pg WHO-TEQ/L) was found to be approximately 55% of magnitude less than that in source water (0.0086 pg WHO-TEQ/L). In addition, the total deposition flux (dry + wet) of PCDD/Fs entering the DWTP-LN was 27.0 ng I-TEQ/m 2 -year, and wet and dry deposition contributed approximately 12.0% and 88%, respectively. It reveals that dry deposition is more important than wet deposition of PCDD/Fs in the ambient air of DWTP-LN. Atmospheric deposition of PCDD/Fs will increase the level in source water of DWTP-LN up to 8.91 × 10 -3 pg I-TEQ/L, which is approximately 92% of the PCDD/Fs in source water. If a removal efficiency of 87% is achieved by conventional treatment processes including coagulation, flocculation, sedimentation and rapid sand filtration, the water after treatment may increase 1.16 × 10 -3 pg I-TEQ/L, which is approximately 43% of the concentration level in tap water. These results indicate that in the DWTP-LN, the influence of atmospheric deposition of PCDD/Fs on the drinking water is of great significance, and water treatment facility with a cover is suggested.

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