Discussion on the mining pollutionand geologic backgroundin Yinyang seaat the northeast cornerof Taiwan

The Yinyang Sea phenomenon in Liandong Bay at the northeast corner of Taiwan is regarded as being the result of pollution caused by ore refining by the Taiwan Metal Mining Corporation. The Taiwan Metal Mining Corporation has been closed since 1987; however, the phenomenon still exists. According to the research findings, the Yinyang Sea phenomenon in Liandong Bay is the result of natural weathering. The suspended substance in the bay is Fe(OH)₃, which is not a pollutant announced by Environmental Protection Administration, and the Fe(OH)₃ is mostly caused by natural weathering reactions; this is why the Yinyang Sea phenomenon occurred before the foundation of the Taiwan Metal Mining Corporation and continues to occur 25 years after the closure of the mine. The distribution of various elements is not uniform, and the original geologic background values of many regions exceed present environmental standards. If the water quality and soil background data of different geologic environments in Taiwan are not investigated as soon as possible, the mining industry may be misrecognized as being responsible for environmental pollution due to unknown geologic anomalies, as Taiwan Metal Mining Corporation was, and this may cause meaningless disputes over economic development and environmental protection.