Records of organic carbon and total nitrogen for environmental changes in the Chukchi Sea during the past 100 years

Five multicores were taken from the Chuckchi Sea Shelf, Chuckchi Sea Plateau and Chuckchi Sea Basin during the fifth Chinese National Arctic Research Expedition in 2012 and the sixth Chinese National Arctic Research Expedition in 2014. All samples were analyzed for ²¹⁰Pb, grain size, organic carbon (OC) concentration and total nitrogen (TN) content as well as stable the isotopes of organic carbon (δ¹³C) and nitrogen (δ¹⁵N). The sedimentation rates of the 5 multicores are 0.19~0.41cm/a in the shelf area, and 0.03~0.04cm/a on the Plateau and in the Basin area. The OC and TN contents are 1.21%~1.62% and 0.17%~0.21% respectively, while the δ¹³C and δ¹⁵N are -22.30‰~-22.25‰PDB and 7.24‰~8.12‰ in the Shelf area during the past 100 years. The OC and TN content are 0.80%~1.26% and 0.13%~0.16% respectively, while the δ¹³C and δ¹⁵N are -22.52‰~-22.07‰PDB and 7.38‰~7.81‰ on the Plateau and in the Basin area during the same period. The OC and TN content as well as the sedimentation rate are higher in the Shelf area than those in the Plateau and Basin. The sediments are coarser in the shelf area than those in the Plateau and Basin area. The OC is mainly from the marine input, suggesting that the Arctic Ocean was warmer and productivity higher in the past 100 years.