A Review of Dissolved Iron Behavior with Respect to Land-use and Land-cover in the Amur River Basin and its Conservation for the Sustainable Future of the Region

摘要

The Amur-Okhotsk Project introduced a new global environmental concept referred to as the “giant-fish breeding forest (GFBF)” by expanding the traditional Japanese idea of uotsuki-rin (fish-breeding forest), which associates upstream forests with the related coastal ecosystem. The project found that primary production in the Sea of Okhotsk and the Oyashio open water region depended on dissolved iron transported from the Amur River and its watershed. Therefore, the Amur River basin could be recognized as a GFBF of the Sea of Okhotsk and the Oyashio region. The dissolved iron originates from natural wetlands in the middle and lower reaches of the Amur River, where land-use and land-cover change rapidly. Therefore, the impact of land-use changes on iron discharge is considered to be significant. In fact, nearly half of the wetlands in the Sanjiang plain were reclaimed in the latter part of the 20th century, resulting in a significant decrease in the concentration of iron in tributary river waters. A numerical simulation suggests further changes in land-use and land-cover in the Amur River basin may decrease the dissolved iron supply to the oceans. We therefore propose to establish an epistemic community for further discussion of ways the GFBF could be used sustaina- bly by various stakeholders in the multilateral countries involved.