Former An-Shun plant, Tainan

The plant was built in 1942 by Kanegafuchi Soda to make caustic soda, hydrochloric acid and liquid chlorine. After the war it passed to the Taiwan Alkali Company. From 1964 it produced sodium pentachlorophenate, used as a herbicide and wood preservative and exported mainly to Japan; from 1969 with a four-tonne-a-day unit. In June 1982 the Ministry of Economic Affairs dissolved the company: the factory closed and passed to China Petrochemical Development Corporation, leaving nearly 5,000 tonnes of pentachlorophenol on the site.

Mercury-cell electrolysis contaminated the sediments of the Luermen area through sludge and effluent. Dioxins, a by-product of pentachlorophenol synthesis, moved into soil and groundwater as the stockpiles were washed by rain. Up to 3,370 mg/kg of mercury and up to 64,100,000 ng I-TEQ/kg of dioxins have been measured in soil (values cited by Mathew and colleagues 2015). Fish in the saltwater pond all exceeded food limits for mercury and dioxins (Liao and colleagues 2016).

The site was listed in 2001 and 2002. In 2007 the Supreme Administrative Court ruled that China Petrochemical, as successor to Taiwan Alkali, inherited its liability. The clean-up combines excavation, soil washing, thermal desorption and, since November 2012, dredging of the pond sediment. Part of the area, with the drainage channel and mangroves, was turned into an environmental education park in 2011. History and dates come from Chinese-language Wikipedia.