Abstract：
Aeolian transport of continental dust from the Middle East and South Asia to the Arabian Sea (AS) is an important route for delivering key trace metals and nutrients. Despite being surrounded by several deserts, it is not clear which dust source is most likely contributing to mineral aerosols over this marine basin in winter. Substantial information on dust source emissions and transport pathways over the AS is, thus, needed for better constraining the biogeochemical effects in the sunlit surface waters. Here, we investigated the Sr and Nd isotopic composition (87Sr/86Sr and εNd(0)), respectively) of dust samples collected over the AS during a GEOTRACES-India expedition (GI-10: 13 January-10 February 2020). Both tracers, 87Sr/86Sr (0.70957-0.72495) and εNd(0) (-24.0 to -9.3), showed pronounced spatial variability. These proxies were further tagged with their source profiles of surrounding land masses based on the origin of air mass back trajectories (AMBTs). We also encountered two dust storms (DS), one on 27 January 2020 (87Sr/86Sr: 0.70957; εNd(0): -9.3) and the second one on 10 February 2020 (87Sr/86Sr: 0.71474, εNd(0):-12.5), which showed distinct isotopic signatures. AMBTs and satellite imagery together revealed that DS1 is from the Arabian Peninsula and DS2 is from Iran and/or the Indo-Gangetic Plain. Notably, the Sr and Nd isotope composition of DS1 is further consistent with other dust samples collected over the pelagic waters, suggesting the impact of dust outbreaks from the Arabian Peninsula during winter season. Such documentation based on the 87Sr/86Sr and εNd(0) over the Arabian Sea, hitherto, is lacking in literature and, thus, highlights the need for more measurements.
摘要：
从中东和南亚到阿拉伯海（AS）的大陆尘埃风尘运输是输送关键痕量金属和营养素的重要途径。尽管被几个沙漠包围，目前尚不清楚冬季哪个粉尘源最可能导致该海洋盆地上的矿物气溶胶。关于烟尘源排放和运输途径的大量信息是，因此，需要更好地限制阳光照射的地表水中的生物地球化学效应。这里,我们研究了Sr和Nd同位素组成(87Sr/86Sr和εNd(0))，分别）在GEOTRACES-印度考察期间收集的AS上的灰尘样本（GI-10：2020年1月13日至2月10日）。两个示踪剂,87Sr/86Sr（0.70957-0.72495）和εNd（0）（-24.0至-9.3），表现出明显的空间变异性。根据空气质量返回轨迹（AMBT）的起源，将这些代理进一步标记为其周围土地质量的来源轮廓。我们还遇到了两次沙尘暴（DS），一个在2020年1月27日（87Sr/86Sr：0.70957；εNd（0）：-9.3），第二个在2020年2月10日（87Sr/86Sr：0.71474，εNd（0）：-12.5），显示出明显的同位素特征。AMBTs和卫星图像一起显示DS1来自阿拉伯半岛，DS2来自伊朗和/或印度恒河平原。值得注意的是,DS1的Sr和Nd同位素组成与在中上层水域收集的其他尘埃样品进一步一致，这表明了冬季阿拉伯半岛沙尘爆发的影响。此类文件基于阿拉伯海上的87Sr/86Sr和εNd（0），迄今为止,缺乏文学，因此，强调需要更多的测量。
