We investigated two sediment cores to understand whether a tsunami in Onagawa Bay, Japan caused environmental changes. The value of δ¹³C ranged from −21.9‰ to −24.3‰ and of δ¹⁵N ranged from 5.1 to 5.9‰. We conclude that the source of the sediment in the present study area was mainly oceanic and not terrestrial. The chlorophyll concentration ranged from 1.8 to 4.0 μg/g ww, and did not vary greatly between surface and bottom layers. We inferred that all layers were deposited after the tsunami. The major phytoplankton taxa in sediments were diatoms from DNA sequencing. The presence of harmful dinoflagellates was minor. The concentrations of several heavy metals decreased slightly after the tsunami. We inferred that heavy metals in sediments were diluted by the tsunami disturbance. The land in Onagawa suffered serious damage, but disturbance of the seabed was much less evident.

我们调查了两个沉积物核心，以了解日本Onagawa湾的海啸是否引起了环境变化。的δ值¹³ Ç范围从-21.9‰至-24.3‰和的δ ¹⁵N在5.1至5.9‰之间。我们得出结论，本研究区的沉积物来源主要是海洋而不是陆地。叶绿素浓度范围为1.8至4.0μg/ g ww，在表层和底层之间变化不大。我们推断海啸过后所有层都沉积了。沉积物中主要的浮游植物类群是来自DNA测序的硅藻。有害的鞭毛藻的存在很小。海啸后，几种重金属的浓度略有下降。我们推断，海啸扰动稀释了沉积物中的重金属。Onagawa的土地遭受了严重破坏，但对海底的干扰却不那么明显。