title: Deposition fluxes of PCDD/Fs in a reservoir system in northern Taiwan.
abstract: In this study, polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/F) concentrations and depositions in ambient air, water column and sediment were measured at a coupled reservoir-watershed system in northern Taiwan. The atmospheric PCDD/F concentration measured in the vicinity of the reservoir ranged from 4.9 to 39 fg I-TEQ m(-3) and the Asian dust storm in February accounted for the peak value, which corresponded to a total suspended particle concentration of 128 μg m(-3). The atmospheric PCDD/F deposition ranged from 1.4 to 19 pg I-TEQ m(-2)d(-1), with higher deposition occurring during winter and spring (long-range transport events). During summer, when atmospheric deposition is lower, consecutive tropical cyclones (typhoons) bring heavy rainfall that enhances soil erosion and creates turbidity-driven intermediate flow. This results in significantly higher PCDD/F deposition in water column of the reservoir at 70 m water depth (179 pg I-TEQ m(-2)d(-1)) than at 20 m (21 pg I-TEQ m(-2)d(-1)) during typhoon event. The accumulation rate of PCDD/Fs (9.1 ng I-TEQm(-2)y(-1)) in the reservoir sediments (depth: 0-2 cm) was consistent with PCDD/F deposition obtained from water column (6.1 and 8.3 ng I-TEQ m(-2)y(-1)); however, it is significantly higher when compared to the atmospheric deposition (2.0 ng I-TEQ m(-2)y(-1)). Based on the mass balance between the measurements of atmospheric deposition and sinking particles in water column, around 54-74% of PCDD/F inputs into the reservoir were contributed by the catchment erosion during normal period. However, the PCDD/F input contributed by the enhanced catchment erosion significantly increased to 90% during intensive typhoon events.
authors: Institute of Environmental and Occupational Health Sciences, National Yang Ming University, Taipei 112, Taiwan. khchi@rcec.sinica.edu.tw
authors: Kai Hsien
authors: KH
authors: Chi
authors: Shih-Chieh
authors: SC
authors: Hsu
authors: Chuan-Yao
authors: CY
authors: Lin
authors: Shuh Ji
authors: SJ
authors: Kao
authors: Tzu Yi
authors: TY
authors: Lee
mesh_terms: D000393:Air Pollutants / Q000032:analysis; D001272:Atmosphere / Q000737:chemistry; D001572:Benzofurans / Q000032:analysis*; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000032:analysis; D011108:Polymers / Q000032:analysis*; D013624:Taiwan; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014881:Water Supply / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D001572:Benzofurans; D000072317:Polychlorinated Dibenzodioxins; D011108:Polymers; D014874:Water Pollutants, Chemical; C016068:polychlorodibenzofuran