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.

受气候变化与极地放大效应（polar amplification）的叠加影响，北极正经历变暖与生态系统变迁。北极阿拉斯加的滨海沼泽环境（如艾斯彭贝角（Cape Espenberg）障壁滩系统）为研究气候变化背景下碳循环的响应提供了契机——这些沉积记录以平行于岸线的线性几何形态的进积地貌特征被长期保存下来。本研究针对艾斯彭贝角的沼泽环境，分别探究了古气候时段（公元1850年前，即生物死亡后的沉积形成时段）与现代时段（公元1850年后）的碳与矿物积累趋势。本研究针对多根沉积岩芯搭建了一套完备的物理与化学数据集，涵盖放射性同位素（铯-137（Caesium-137, ¹³⁷Cs）、铅-210（Lead-210, ²¹⁰Pb）、碳-14（Carbon-14, ¹⁴C））、稳定同位素（碳同位素δ¹³C（delta-13 Carbon））、元素浓度（总碳占比[C]、总氮占比[N]、碳氮比[C:N]）以及干容重等指标。研究结果显示，从古气候时段到现代时段，碳与矿物的积累量均有所上升，这或与现代气候下有机质拥有更优的生长与保存条件有关。中世纪暖期（Medieval Climate Anomaly, MCA）的古气候趋势，以及小冰期（Little Ice Age, LIA）内零星分布的暖期，均与湿地有机质贡献占比的提升呈现相关性，这一点可通过更轻的δ¹³C值得到佐证。小冰期内的寒冷气候时段则与水生有机质贡献占比上升及更重的δ¹³C值相关，且小冰期内还零星出现了湿地有机质贡献占比的峰值事件。正如艾斯彭贝角的洼地环境所观测到的那样，未来全球气候变化将导致气温持续上升，现代变暖趋势或进一步推动北极滨海湿地的碳储量增长：彼时更适宜的有机质生长与土壤保存条件（即湿润/缺氧的土壤、更低的盐度以抑制有机质分解、更高的温度以促进生长），将助力未来北极滨海碳库的形成。