Elevated Anthropogenic Contributions to Trace Elements in Marine Aerosols Compared to Coastal Qingdao in Eastern China

Trace elements (TEs) in aerosols over offshore eastern China originate from both terrestrial and marine emissions. However, their variations with source regions remain poorly understood. During spring and summer 2018, PM_2.5 samples were collected at Qingdao, a coastal city in eastern China, and adjacent Bohai and Yellow Seas. TEs were quantified and analyzed by source region, followed by source apportionment. In spring, TE concentrations were significantly higher over land. Crustal dust contributed 39.2–77.8% of Fe, Mn, Cr and Ni; while waste and industrial emissions contributed 29.4–70.1% of Cu, Zn and Pb. Westerly winds conveyed anthropogenic TEs offshore, with coal combustion contributing 25.9–61.4% to As, Cd, Pb, Zn and Cr, and oil combustion contributing 58.6–84.4% to V and Ni in marine aerosols, indicating efficient long-range pollutant transport. In summer, dust influence declined. Biomass burning contributed 38.2–46.3% of Zn, Cd, Pb and Cr, while vehicular emissions dominated As and Cu (41.7–57.3%) at Qingdao. Over marine areas, anthropogenic elements (Zn, As, and Cd) occasionally exceeded coastal levels, with coal combustion remaining dominant (40.8–75.5%). Ship emissions became especially prominent, contributing 79.3% of V and 63.3% of Ni offshore. Southeasterly winds transported ship-derived pollutants coastward, markedly increasing Fe (21.2%) and Mn (14.0%) compared to spring (1.9% and 1.8%, respectively). These results reveal distinct seasonal shifts in TE source across land-sea gradients, highlighting growing anthropogenic impacts, particularly from coal combustion and maritime shipping on marine aerosols. Quantifying these contributions helps assess marine biogeochemical impacts and supports targeted pollution control.

痕量元素（Trace Elements, TEs）在中国东部近海大气气溶胶中的来源兼具陆地与海洋排放。然而，其随源区变化的分布特征仍未得到充分阐明。2018年春夏两季，研究团队于中国东部沿海城市青岛及邻近的渤海、黄海海域采集了细颗粒物（PM₂.₅）样品。对其中的痕量元素进行了定量检测与源区分类分析，并完成了污染源解析（source apportionment）工作。春季期间，陆地气团中的痕量元素浓度显著更高。地壳扬尘对铁（Fe）、锰（Mn）、铬（Cr）及镍（Ni）的贡献率达39.2%–77.8%；而废弃物与工业排放对铜（Cu）、锌（Zn）及铅（Pb）的贡献率为29.4%–70.1%。西风将人为源痕量元素输送至近海海域：燃煤燃烧对海洋气溶胶中的砷（As）、镉（Cd）、铅（Pb）、锌（Zn）及铬（Cr）的贡献率为25.9%–61.4%，燃油燃烧对钒（V）及镍（Ni）的贡献率达58.6%–84.4%，这表明污染物可实现高效长距离传输。夏季时，地壳扬尘的影响有所减弱。生物质燃烧对锌（Zn）、镉（Cd）、铅（Pb）及铬（Cr）的贡献率为38.2%–46.3%；而机动车排放主导了青岛地区的砷（As）与铜（Cu），贡献率达41.7%–57.3%。在海洋海域，人为源元素（锌（Zn）、砷（As）及镉（Cd））偶尔会超过沿海区域浓度水平，其中燃煤燃烧仍占主导地位（40.8%–75.5%）。船舶排放的贡献尤为突出，对近海海域钒（V）的贡献率达79.3%，对镍（Ni）的贡献率为63.3%。东南风将船舶排放的污染物输送至沿海区域，与春季相比，这显著提升了铁（Fe，21.2%）与锰（Mn，14.0%）的浓度占比（春季仅分别为1.9%与1.8%）。本研究结果揭示了陆海梯度下痕量元素来源的显著季节差异，凸显了人为活动影响的不断增强，尤其是燃煤燃烧与海运活动对海洋气溶胶的影响。量化上述来源贡献，有助于评估其对海洋生物地球化学过程的影响，并为针对性污染防控提供支撑。