PCBs in Donggang River Watershed sediments, Taiwan.

Polychlorinated biphenyls (PCBs) were measured in the sediments of the Donggang River Watershed, one of the most polluted bodies of water in southern Taiwan. Field data showed that detectable concentrations of 121 PCB congeners were found and total PCBs were measured in 32 out of 33 samples, and 98 congeners were detected. The total concentrations of PCBs in the sediment ranged from 25.5-63.5 ngg(-1) dw with a geometric mean ± standard deviation of 4.00 ± 1.73 ngg(-1) dw, with one sample below the detection limit. The highest concentration (20.79 ngg(-1) dw) was found at the most downstream sampling site near the head of the estuary, while average levels were highest at the tributary sampling site, ranging from 8.81-019.4 ngg(-1) dw. In general, the average concentrations in the tributary sampling sites were higher than those in the main stem sampling sites, which were 24.02 ± 10.15 and 19.97 ± 8.9 ngg(-1) dw, respectively. Among the 121 congeners, congener 1, 3, 22, 25, 33, 21, 53, 47, 41, 64, 71, 107, 136, 146, 158, 157, 200, 172, 189, 207, 205, 206, and 209 were all below the detection limit and were not found in any samples. Congeners 191, 85, and 26 were the most commonly detected, however, PCB 26, 12+13, and 52 were the most abundant congeners and contributed 11.5, 8.4, and 6.96% to the total PCBs, respectively. The results indicated that trace PCBs were still detectable in the sediment of the Donggang River and its tributaries. However, the concentrations were considerably lower than those found in other studies of nearby areas in Taiwan and around the world.

Characteristics and distribution of polycyclic aromatic hydrocarbons in sediments from Donggang river and its tributaries, Taiwan.

Analyses of environmental xenobiotic pollutants, such as polycyclic aromatic hydrocarbons (PAHs), were an important worldwide issue because of their detrimental effects on aquatic biota. In this study, we had investigated the distribution, origin and toxicity of PAHs in the Donggang watershed sediments in southwestern Taiwan. The study results showed that the sixteen representative PAHs were detected in all collected samples with concentrations ranging from 23 to 2534 ngg(-1) dw. The highest concentration was detected in the downstream end at near the estuarine portion of the river. The mean ± standard deviation and median of ΣPAH concentrations were 528.5 ± 72.3 and 156 ngg(-1) of dry matrix in collected samples. The highest and lowest concentrations of Σ16 PAHs samples differed significantly (p < 0.05) and naphthalene, phenanthrene, fluoranthene and pyrene were detected in all sediment samples. The random variations between sampling sites were consistent with watershed land use. The present study showed that the ratios of phenanthrene/anthracene (Phe/Ant) and fluoranthane/pyrene (FLu/Pyr) in samples suggested that PAHs sources exhibited mixed pattern of petrogenic and pyrolytic inputs. The PAHs with high molecular weight (5-6 ring) accounted for 95.5% of total-BaPeq while the low molecular weight PAHs (2-3 ring) only appeared 0.20%. There was a high correlation (R(2)= 0.967) between mean concentrations and the BaPeq of the PAHs within the sediments. In summary, the adverse biological effect was low according to the effects-range-low (ERL) values of the Sediment Quality Guidelines (SQGs) in sediments from Donggang river and its tributaries in Taiwan.