Tahan River most toxic in Taiwan: survey

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Taipei, Dec. 5 (CNA) A survey on the sources of sediment pollution in the Tahan River, a tributary of the Danshui River, will be launched soon as part of the government's efforts to clean up Taiwan's major rivers, the Environmental Protection Administration (EPA) said Monday. "Tahan becomes the first investigation target because initial surveys show that its sediment has suffered the most serious heavy metal pollution among all domestic rivers," said Tsai Hung-teh, executive secretary of the EPA's Soil and Groundwater Pollution Remediation Fund Management Board. The new survey will focus on tracking the sources of pollution and how the pollutants are spread, Tsai said after an expert meeting on river pollution issues. According to Tsai, the board began to investigate water and sediment pollution in major domestic rivers in 1997 and has so far completed surveys of heavy metals and other organic pollutants in 27 local rivers. "It was discovered that water and sediment of over one-third of those rivers were seriously polluted," Tsai said, adding that the Tahan River was found to have the highest copper content in its sediment among all local rivers. The river also ranked among the top five in terms of zinc and nickel content levels in its sediment and water quality, Tsai said. The new survey will start from the Sanying Bridge in the upper stretch of the Tahan River and end at the estuary 6of the Danshui River, Tsai said, adding that the Danshui River's two other branches -- the Sindian and the Keelung rivers -- will also be covered in the study. "The project will cost about NT$21 million (US$697,200) and is scheduled for completion at the end of 2013," Tsai said. It was also decided at Monday's meeting that in coming years similar investigations will be carried out at 10 other polluted rivers -- Nankan, Laochieh, Sinhuwei, Jhuoshuei, Jishui, Yenshui, Erjen, Lover, Beigang and Aguengdian rivers. Meanwhile, the New Taipei City Government reminded its citizens not to harvest vegetables grown on artificial wetlands along the Tahan and Danshui rivers because such crops may contain toxic chemicals or heavy metals. "The vegetables have been planted to help purify river water, but they are not edible because some of them may absorb toxic pollutants in the river water or sediment," said a city official. (By Zoi Wei, Sunrise Huang and Sofia Wu)