Sediment Core Data from Cape Espenberg, Alaska, 2018-2022

The Arctic is experiencing warming and ecological shifts due to climate change and the compounded effects of polar amplification. Arctic Alaskan coastal marsh environments, such as the Cape Espenberg barrier beach system, offers an opportunity to determine the carbon cycle response to changing climate in sediment records that have been preserved through time as a shoreline-parallel, linear geometry prograding geomorphic features. This study determines the carbon and mineral accumulation trends in marsh environments at Cape Espenberg for both paleo (pre 1850 after death [AD]) and modern (post 1850 AD) timeframes. A comprehensive physical and chemical dataset, including radioisotope (Caesium-137 [137Cs], Lead-210 [210Pb], Carbon-14 [14C]), stable isotope (delta-13 Carbon [δ13C]), element concentration (%Carbon [C], %Nitrogen [N], C:N), and dry bulk density, has been built for several sediment cores. Results indicate carbon and mineral accumulations have increased from paleo to modern times, potentially due to better growing and/or preservation conditions for organic matter under a modern climate. Paleoclimate trends in the Medieval Climate Anomaly (MCA), and warm periods interspersed within the Little Ice Age (LIA), also correlate to greater contributions of wetland organic matter as evidenced by lighter δ13C values. Cold climate periods within the Little Ice Age correlate with increased aquatic organic matter sourcing and heavier δ13C values with some spikes of wetland sources interspersed throughout the LIA. Modern warming may potentially continue to expand carbon stores in Arctic coastal wetlands as future temperatures are predicted to rise with global climate change, as observed in the swale environments at Cape Espenberg, where increasingly favorable growing and soil preservation conditions (i.e. wet/anoxic soils and lower salinity to limit organic material decay, higher temperatures to promote growth) may result in future Arctic coastal carbon reservoirs.

由于气候变化与极地放大效应（polar amplification）的复合影响，北极地区正经历变暖与生态变迁。北极阿拉斯加的海岸沼泽环境——例如艾斯彭伯格角（Cape Espenberg）障壁滩系统（barrier beach system）——为我们通过沉积记录研究碳循环对气候变化的响应提供了契机：这些沉积记录以平行于海岸线的线性几何形态的进积地貌（prograding geomorphic features）特征被长期保存下来。本研究针对艾斯彭伯格角的沼泽环境，分别重建了古时段（公元1850年之前，即生物死亡发生于公元纪年后的时段）与现代时段（公元1850年之后）的碳与矿物积累趋势。研究团队已针对多根沉积岩芯（sediment cores）构建了一套综合物理与化学数据集，涵盖放射性同位素（radioisotope）铯-137（Caesium-137 [¹³⁷Cs]）、铅-210（Lead-210 [²¹⁰Pb]）、碳-14（Carbon-14 [¹⁴C]），稳定同位素（stable isotope）碳同位素δ¹³C（delta-13 Carbon [δ¹³C]），元素浓度指标包括总碳百分比（%Carbon [C]）、总氮百分比（%Nitrogen [N]）及碳氮比（C:N），此外还包含干容重（dry bulk density）数据。研究结果显示，从古时段到现代，碳与矿物积累量均有所上升，这可能得益于现代气候下有机质更优的生长与/或保存条件。中世纪气候异常期（Medieval Climate Anomaly [MCA]）以及小冰期（Little Ice Age [LIA]）内零星出现的暖期的古气候趋势，均与湿地有机质贡献占比提升存在关联，这一点可通过偏轻的δ¹³C值得到佐证。而小冰期内的寒冷时段则与水生有机质贡献占比提升、偏重的δ¹³C值存在关联，且小冰期内还零星出现了湿地有机质贡献占比激增的事件。正如艾斯彭伯格角的湿洼地（swale）环境所观测到的那样，未来全球气候变化将导致气温进一步升高，现代变暖趋势或持续推动北极海岸湿地的碳储量扩张：届时更适宜的植物生长与土壤保存条件——即湿润/厌氧的土壤环境、更低的盐度以抑制有机质降解、更高的温度以促进生物生长——或进一步提升北极海岸的碳库容量。