CSIR-National Institute of Oceanography (NIO), Goa
Integrative Oceanography Division, CSIR-National Institute of Oceanography (NIO) Dona Paula, North Goa, Goa, India Pincode: 403004 Mobile: 7396925320 E-mail: firstname.lastname@example.org
The long-range atmospheric transport of mineral dust from the Middle East and South Asia to the Arabian Sea is an important route for delivering key trace metals and nutrients1. Despite being surrounded by the vast majority of deserts, it is not clear which dust source is most likely contributing to mineral aerosols over the Arabian Sea. Therefore, understanding the dust source and transport pathways over the Arabian Sea are needed for better constraining the biogeochemical effects in the sunlit surface waters. Here, we investigated the radiogenic Sr and Nd isotopic composition (87Sr/86Sr and Nd(0)), respectively) of dust samples collected over the Arabian Sea during a winter cruise (13 January-10 February 2020). The 87Sr/86Sr ratios of dust samples from the Arabian Sea varied between 0.7097 and 0.7236, whereas theεNd(0) ranged between -12.4 and -6.3. More specifically, the dust samples collected alongside the east coast of the Arabian Sea are more enriched in radiogenic Sr (87Sr/86Sr: 0.7164-0.7236) but contained less radiogenic Nd (εNd(0): -12.4 to -10.3) compared to those collected over the open ocean waters (87Sr/86Sr: 0.7097-0.7153; εNd(0): -9.4 to -6.3). These proxy signatures were further tagged with their provenance based on the origin of backward air mass trajectories, which are computed using the hybrid single-particle lagrangian integrated trajectory model (HYSPLIT) for the sampling days and, then, compared with the source profiles of dust from the Middle East and India. Besides, the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite retrievals of vertical sections over the Arabian Sea also corroborate the presence of mineral dust particles at higher heights. Overall, our results underscore the significance of aeolian dust from the Arabian Peninsula through high altitude transport in addition to that of mineral aerosols from the Thar Desert during the impact of South Asian outflow to the Arabian Sea.