Geochemistry, fluxes and nitrogen isotopic composition data of traps LP1 and EBC2-1 and cores GeoB4242-4 and Geo4301-1

We compare total and biogenic particle fluxes and stable nitrogen isotope ratios (d15N) at three mooring sites along a productivity gradient in the Canary Islands region with surface sediment accumulation rates and sedimentary d15N. Higher particle fluxes and sediment accumulation rates, and lower d15N were observed in the upwelling influenced eastern boundary region (EBC) compared to the oligotrophic sites north of Gran Canaria [European Station for Time-Series in the Ocean, Canary Islands (ESTOC]] and north of La Palma (LP). The impact of organic matter degradation and lateral particle advection on sediment accumulation was quantified with respect to the multi-year flux record at the ESTOC. Remineralisation of organic matter in the water column and at the sediment surface resulted in an organic carbon preservation of about 0.8% and total nitrogen preservation of about 0.4% of the estimated export production. Higher total and carbonate fluxes and accumulation rates in the lower traps and surface sediment compared to the upper traps indicated that at least 50% of the particulate matter at the ESTOC was derived from allochthonous sources. Low d15N values in the lower traps of the ESTOC and LP point to a source region influenced by coastal upwelling. We conclude from this study that the reconstruction of export production or nutrient regimes from sedimentary records in regions with strong productivity gradients might be biased due to the mixture of particles originating from autochthonous and allochthonous sources. This could result in an imprint of high productivity signatures on sedimentation processes in oligotrophic regions.

本研究针对加那利群岛区域沿生产力梯度布设的3个锚泊站位，对比了其总颗粒通量、生源颗粒通量与稳定氮同位素比值（δ¹⁵N，stable nitrogen isotope ratios），并将上述参数与对应站位的表层沉积物堆积速率及沉积物δ¹⁵N进行关联分析。相较于大加纳利岛北部的寡营养站位[欧洲加那利群岛海洋时间序列站（European Station for Time-Series in the Ocean, Canary Islands, ESTOC）]与拉帕尔马岛北部站位，受上升流影响的东边界区域（Eastern Boundary Region, EBC）呈现出更高的颗粒通量与沉积物堆积速率，以及更低的δ¹⁵N值。
本研究以ESTOC站的多年通量观测记录为参照，量化了有机质降解与颗粒物质侧向平流对沉积物堆积过程的影响。水体及沉积物表层的有机质再矿化作用，使得有机碳保存率约为估算输出生产力的0.8%，总氮保存率约为0.4%。相较于上层沉积物捕获器，下层捕获器与表层沉积物的总颗粒通量、碳酸盐通量及堆积速率均更高，这表明ESTOC站位至少50%的颗粒物来源于外源来源（allochthonous sources）。ESTOC站与拉帕尔马岛北部站位的下层捕获器中δ¹⁵N值偏低，这表明其物质来源受沿岸上升流影响。
本研究据此得出结论：在具有显著生产力梯度的区域，利用沉积物记录重建输出生产力或营养盐格局时，可能会因内源来源（autochthonous sources）与外源来源的颗粒物混合而产生偏差。这种偏差可能会使得寡营养区域的沉积过程中留下高生产力的信号印记。