Aerosol Nutrients and Their Biological Influence on the Northwest Pacific Ocean (NWPO) and Its Marginal Seas

SIMPLE SUMMARY: With intensifying human activities in the past decades, East Asia has recorded increasingly severe air pollution and become the second largest aerosol source on earth. The large quantity of aerosol emissions is not only a major health threat to humans, but can also be transported for a long distance and deposited in downwind seas and oceans. The aerosol contains major ions, heavy metals, and organic matters that are important external nutrients in upper oceans and potentially influence marine microbes and biogeochemical cycles. Therefore, the role of atmospheric deposition to oceans has received growing attention in recent years. In this paper, the current state of knowledge on the atmospheric nutrients and the biological effect of East Asian aerosol deposition on the northwest Pacific Ocean are reviewed, which could help us better understand the comprehensive influence of East Asian aerosols on marine ecosystems, and give insights into future research directions, especially under the future scenarios of changing human activities and climate. ABSTRACT: Atmospheric deposition is recognized as a significant source of nutrients in the surface ocean. The East Asia region is among the largest sources of aerosol emissions in the world, due to its large industrial, agricultural, and energy production. Thus, East Asian aerosols contain a large proportion of anthropogenic particles that are characterized by small size, complex composition, and high nutrient dissolution, resulting in important influences on marine microbes and biogeochemical cycles in the downwind areas of the northwest Pacific Ocean (NWPO). By using remote sensing, modeling, and incubation experimental methods, enhanced primary production due to the East Asian aerosol input has been observed in the NWPO, with subsequent promotion and inhibition impacts on different phytoplankton taxa. Changes of bacterial activity and diversity also occur in response to aerosol input. The impact of East Asian aerosol loadings is closely related to the amount and composition of the aerosol deposition as well as the hydrological condition of the receiving seawater. Here, we review the current state of knowledge on the atmospheric nutrients and the effects of the East Asian aerosols on microbes in the NWPO region. Future research perspectives are also proposed.