抄録
Scientific articles and governmental reports concerning heavy metal levels and their sources in Japanese surface waters are reviewed. Heavy metal emissions, thus concentrations in the environment, largely decreased since the high-growth period of the 1960s and 1970s. The emission controls taken by industry and the progress of sewerage systems have decisively contributed to decrease heavy metal levels in the environment. Compared to the high-growth period, inputs from diffuse sources play an important role in the overall heavy metal emissions, especially for Zn and Cu, in surface waters. Studies describing the past and the current levels of heavy metals in surface waters suggested that a decline of heavy metal concentrations became obvious over the last few decades, but the present heavy metal levels found in vicinity of the sources still remains a problem in terms of the the aquatic life protection. Properly designed monitoring programs are needed to implement realistic and effective risk management strategies for heavy metal contamination in surface waters
