Enhanced Anthropogenic Contributions to Marine Aerosols and trace elements Compared to Coastal Regions in Northern China

Terrestrial aerosols, transported by westerly winds from Asian continent, continuously deliver both natural and anthropogenic nutrients to downstream marine ecosystems. This study quantified the trace elements in fine particles (PM_2.5) collected concurrently in a coastal city (Qingdao) in Northern China, and across the adjacent sea areas (Yellow and Bohai Sea) during the spring and summer of 2018, to investigate the widespread and sources of aerosols and elements over East Asia marginal areas. Trace elements generally exhibited higher levels in Qingdao compared to marine areas. However, anthropogenic elements, like Zn, Pb, As and Cd showed even higher concentrations in summer marine envrionemnt compared to the coastal site. Through positive matrix factorization (PMF) analysis, it is identified that dust and secondary nitrate contributions to PM_2.5 decreased dramatically from an average of 48.3% in coastal to 19.7% in marine environment. Conversely, anthropogenic sources were more prevalent over the ocean, particularly vehicular emissions (18.5%) and residual oil combustion (9.0%). Specifically, coal comubstion was identified as a dominant source, contributing more than half of Fe and Mn concentrations in the summer marine environment. The disparities in elemental sources between land and sea across different seasons were influenced by several key factors, inlcuding the aerosols sources, airmass history, weather conditions and the mixing with dust. These results highlight significant interaction between sea salt and dust or anthropogenic elements, which may enhance the solubility of these trace elements. This study underscores the potential far-reaching impact of these fine particles on marine ecosystems in East Asian marginal seas.

源自亚洲大陆的陆地气溶胶经西风输送，持续向下游海洋生态系统输送自然及人为来源的营养物质。本研究量化了2018年春夏两季在中国北方沿海城市（青岛）及邻近海域（黄海、渤海）同步采集的细颗粒物（PM₂.₅）中的微量元素，旨在探究东亚边缘海域气溶胶及元素的分布范围与来源。总体而言，青岛的微量元素含量高于海洋区域。然而，Zn、Pb、As及Cd等人为源元素在夏季海洋环境中的浓度甚至高于沿海站点。通过正定矩阵分解（PMF）分析发现，粉尘和二次硝酸盐对PM₂.₅的贡献从沿海区域的平均48.3%显著下降至海洋环境的19.7%。相反，人为源在海洋区域更为普遍，尤其是机动车排放（18.5%）和残油燃烧（9.0%）。具体而言，煤炭燃烧被确定为夏季海洋环境中Fe和Mn浓度的主导来源，贡献占比超过一半。不同季节陆-海元素来源的差异受多个关键因素影响，包括气溶胶来源、气团历史、气象条件及与粉尘的混合作用。这些结果凸显了海盐与粉尘或人为源元素之间的显著相互作用，这可能提高这些微量元素的溶解度。本研究强调了这些细颗粒物对东亚边缘海域海洋生态系统的潜在深远影响。