Bulk Aerosol Trace Element Concentrations and Deposition Fluxes During the U.S. GEOTRACES GP15 Pacific Meridional Transect
Bulk Aerosol Trace Element Concentrations and Deposition Fluxes During the U.S. GEOTRACES GP15 Pacific Meridional Transect
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DOI：
10.1029/2021gb007122
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发表时间：
2022-01
影响因子：
5.2
通讯作者：
C. Marsay;D. Kadko;W. Landing;C. Buck
中科院分区：
文献类型：
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作者：
C. Marsay;D. Kadko;W. Landing;C. Buck
来自大陆的气溶胶在大气中的沉降是海洋营养盐和污染物微量元素的重要来源。在阿拉斯加和塔希提岛之间的美国GEOTRACES GP 15太平洋经向断面（2018年9月至11月）期间，在北太平洋和赤道太平洋收集了气溶胶样本，并分析了一系列TE，包括Al，Ti，V，Cr，Mn，Fe，Co，Ni，Cu，Zn和Pb。采样正好与每年最低的尘埃运输从亚洲，提供了一个机会，以量化气溶胶TE浓度和沉积在低沙尘季节。然而，在北纬40-50度测量的“地壳”TE的峰值浓度（145 pmol/m3 Fe）与来自北方亚洲的输送有关，赤道太平洋的浓度较低（36 ± 14 pmol/m3 Fe）。相对于地壳丰度，赤道太平洋气溶胶通常有较高的TE富集因子比北太平洋气溶胶。相比之下，气溶胶V更丰富的北太平洋，大概是由于更多的供应，这一地区的石油燃烧产物。体积沉积速度（Vbulk）计算沿着断面使用的天然存在的放射性核素，7 Be和气溶胶7 Be活性的表面海洋衰变清单。热带辐合带内的沉降速度（4，570 ± 1，146 m/d）明显高于其他地方（1，764 ± 261 m/d），这是由于强降雨清除了气溶胶。利用Vbulk和气溶胶TE浓度数据计算了沙尘季节中太平洋的日沉降通量，Fe通量范围为19 - 258 nmol/m2/d。
Atmospheric deposition of aerosols transported from the continents is an important source of nutrient and pollutant trace elements (TEs) to the surface ocean. During the U.S. GEOTRACES GP15 Pacific Meridional Transect between Alaska and Tahiti (September–November 2018), aerosol samples were collected over the North Pacific and equatorial Pacific and analyzed for a suite of TEs, including Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Pb. Sampling coincided with the annual minimum in dust transport from Asia, providing an opportunity to quantify aerosol TE concentrations and deposition during the low dust season. Nevertheless, peak concentrations of “crustal” TEs measured at ∼40–50°N (∼145 pmol/m3 Fe) were associated with transport from northern Asia, with lower concentrations (36 ± 14 pmol/m3 Fe) over the equatorial Pacific. Relative to crustal abundances, equatorial Pacific aerosols typically had higher TE enrichment factors than North Pacific aerosols. In contrast, aerosol V was more enriched over the North Pacific, presumably due to greater supply to this region from oil combustion products. Bulk deposition velocity (Vbulk) was calculated along the transect using the surface ocean decay inventory of the naturally occurring radionuclide, 7Be, and aerosol 7Be activity. Deposition velocities were significantly higher (4,570 ± 1,146 m/d) within the Intertropical Convergence Zone than elsewhere (1,764 ± 261 m/d) due to aerosol scavenging by intense rainfall. Daily deposition fluxes to the central Pacific during the low dust season were calculated using Vbulk and aerosol TE concentration data, with Fe fluxes ranging from 19 to 258 nmol/m2/d.