The investigation of organic matter sources is an especially challenging issue for marine coastal areas influenced by both natural and anthropogenic inputs. This study focuses on the provenance of sedimentary organic matter deposited in the Gulf of Gdańsk (southern Baltic) and Oslofjord/Drammensfjord (southern Norway) based on the analysis of multiple specific proxies in recent sediments (0–5 cm layer) sampled at 12 sites in 2014. Bulk markers (total organic carbon/total nitrogen [TOC/TN] and stable organic carbon isotopes [δ¹³C_TOC]) and various molecular geochemical markers of organic matter origin (n-alkanes, branched alkanes, unresolved complex mixture [UCM], polycyclic aromatic hydrocarbons [PAHs], hopanes, steranes, and polar steroids including sterols and stanols) were used to comprehensively assess the origin of sedimentary organic matter in the studied basins. The results of this study indicate that the combined use of TOC/TN and δ¹³C_TOC may lead to ambiguous outcomes, and anthropogenic input may affect the sedimentary TOC/TN ratio. The analysis of molecular proxies allowed the identification of locations most impacted by anthropogenic organic matter derived from petrogenic sources and/or sewage effluents and the classification of the studied sites based on the contribution of marine/terrestrial biogenic matter. This study demonstrates that key issues, such as the forms of sedimentary chemical markers, post-depositional changes, and specific diagenetic products, although neglected by some researchers, must be considered for the reliable assessment of organic matter sources. To the best of our knowledge, this is the first such extensive study on surface sediments from the Gulf of Gdańsk and Oslofjord/Drammensfjord in terms of the use of both bulk and molecular markers to investigate organic matter sources.

对于受自然和人为输入影响的海洋沿海地区，有机物质来源的调查是一个特别具有挑战性的问题。本研究基于对最近在 12 个地点采样的沉积物（0-5 厘米层）中的多个特定代理的分析，重点研究沉积在格但斯克湾（波罗的海南部）和奥斯陆峡湾/德拉门斯峡湾（挪威南部）的沉积有机质的来源2014 年。批量标记（总有机碳/总氮 [TOC/TN] 和稳定有机碳同位素 [δ ¹³ C _TOC]) 和有机质来源的各种分子地球化学标记（正构烷烃、支链烷烃、未解析的复杂混合物 [UCM]、多环芳烃 [PAHs]、藿烷、甾烷和包括甾醇和甾烷醇在内的极性类固醇）被用于综合评估研究盆地中沉积有机质的来源。本研究结果表明，TOC/TN与δ ¹³ C _TOC的联合使用可能导致模棱两可的结果，人为输入可能会影响沉积的 TOC/TN 比。分子代理的分析可以确定受来自岩石源和/或污水流出物的人为有机物质影响最大的位置，并根据海洋/陆地生物物质的贡献对研究地点进行分类。这项研究表明，尽管被一些研究人员忽视，但必须考虑关键问题，例如沉积化学标记的形式、沉积后变化和特定的成岩产物，以可靠地评估有机质来源。据我们所知，