In this study, PCDD/F deposition was measured at Sun Moon Lake via automated PCDD/F ambient air precipitation sampler and traditional cylindrical vessels from January 2009 to December 2009. Significantly higher atmospheric PCDD/F deposion flux (1.88 to 2.95 pg-I-TEQ/m2-day) were measured at this area in April 2009. Additionally, the sampling results also indicate that the PCDD/F deposition fluxes measured with the automated PCDD/F precipitation sampler (1.32 to 3.43 pg-I-TEQ/m2-day) are higher than that sampled with cylindrical vessels (0.978 to 2.95 pg-I-TEQ/m2-day). That is attributed to the fact that part of PCDD/Fs collected by traditional cylindrical vessels are photodegraded. Furthermore, the wet deposition flux of PCDD/Fs (17.3 to 471 pg-I-TEQ/m2-rainy day) observed in this study is significantly higher than dry deposition flux (0.379 to 2.55 pg-I-TEQ/m2-sunny day). This study also reports vertical profiles of a wide variety of PCDD/F in a sediment core, collected from different locations of Sun Moon Lake. The PCDD/F contents in sediment cores measured at Southern bay (1.64 ~ 4.78 ng-I-TEQ/kg d.w.) of Sun Moon Lake quite higher than those measured at outlet (0.917 ~ 2.89 ng-I-TEQ/kg d.w.) and central (0.092 ~ 1.91 ng-I-TEQ/kg d.w.) of Sun Moon Lake. Our results also demonstrated that PCDD/F concentrations in the sediment core at Southern bay started to increase at a depth of 14-16 cm and reached the peak (4.78 ng-I-TEQ/kg d.w.) at 12-14 cm. Based on the results of isotope analysis in sediment core collected in Sun Moon Lake, the estimated year of the sediment core at the depth of 12-14 cm is 1973. In 1973, the Taiwan government proposed the regulation of DDT use in 1973. In addition, the variation of PCDD/F contents in different depth of sediment core is similar to that of the pesticides (PCP and CNP) production in Taiwan. The previous report indicated that higher productions of PCP and CNP were observed in 1975 and 1986, respectively. Therefore, the PCDD/F contents in the sediment cores at depth 6-10 cm (estimated age: 1985 to 1991) did not decrease significantly.

Dioxin, POP, deposition, core