This project collected sediment samples from ten Taiwanese rivers (i.e., Nankan River, Jhonggang River, Houlong River, Da-an River, Wu River, Yanshuei River, Dian Bao River, Donggang River, Lanyang River and Shincheng River) to determine concentrations of toxic substances such as short-chain chlorinated paraffins (SCCPs), mirex, nonylphenol (NP), bisphenol A (BPA), phthalate esters (PAEs), polybrominated diphenyl ethers (PBDEs), hexabrominated biphenyls (HBBs), organic and inorganic arsenic. The analysis of sediment samples was completed and 4,374 analyzed data were obtained. The concentrations of SCCPs with 55.5% chlorine content were higher than SCCPs with 63% chlorine content in sediment samples collected from ten Taiwanese rivers in this year. Among eight SCCPs with different chain lengths and chlorine contents, the SCCPs with chain length of C10 showed the highest concentration in sediment samples. Thus, it is necessary to continually investigate the concentrations of SCCPs in sediments of the other twenty Taiwanese rivers in order to establish backgroup levels of SCCPs (belonging to persistent organic pollutants, POPs) in Taiwanese rivers. To integrate the past investigation data, the concentrations of mirex in sediments of 30 Taiwanese major rivers were relatively low. Therefore, the investigation of mirex in river sediments could be suspended and no any control strategy needed. The concentrations of NP and BPA in sediments of 30 rivers almost decreased with time. However, the concentrations of NP in sediments of some rivers were higher than the other rivers or those of BPA increased in this year. Therefore, advanced control strategies for NP and BPA such as set limit level of NP in detergent for industrial usage is recommended. The recent 3-year survey showed that the average DEHP concentrations in sediments from Danshuei River, Sindian River, Keelung River, Linbien River were still higher than 1.97 mg/kg (the lower limit of sediment quality). The two-stage long-term survey on PBDEs in the river environment showed that there was no decreasing trend on the concentrations of PBDEs in the river sediments. It is suggested that environmental monitoring of PBDEs and DEHP should be continued and a review of control policies is needed. The concentrations of organic and inorganic arsenic were much lower than the lower limit of sediment quality for total arsenic. The future work on the environmental survey of toxic substances distribution was proposed and 19 priority toxic substances were suggested for environmental survey. “The database searching website for environmental distribution of toxic substances” was continuously maintained. “The handbook of investigation achievements on the toxic substances distribution in Taiwan, version 2017” was published as an e-book.

Toxic substances, Environmental distribution, River sediment