沿岸域堆積物-海水界面における鉛 (Pb) 移動性への地球温暖化の影響

抄録

Ocean acidification (decreased pH) and rising temperatures caused by global warming may weaken the bonds that bind toxic heavy metals to sediment particles, potentially increasing their solubility in seawater and posing greater ecological risks. This study aims to understand the current behavior and potential solubility of toxic heavy metals, particularly lead (Pb), in a semi-closed coastal area (West Nanao Bay). Initial results of two cores show significant increases, at least by a factor of 1.5, in detrital Pb since the 1950s for NW-11 and NW-7 cores. Most elements showed minor enrichment factors (EF ＜ 3), reflecting an anthropogenic input. Mining, fossil fuel combustion, maritime transport, and land use changes were associated with the temporal changes in sediments. High concentrations of toxic metals within the uppermost surface sediments (0-10 cm) pose a potential risk due to their high solubility rates. They could potentially accumulate in higher predators through the food chain. Furthermore, additional Nanao Bay sediments are needed to estimate the solubility of toxic metals under different pH and temperature conditions.