Contribution of marine biological emissions to gaseous methylamines in the atmosphere: an emission inventory based on satellite data
Abstract. Methylamines can readily react with acidic gases in the atmosphere, which consequently has an important impact on the atmospheric environment. It is difficult to measure amines in field studies due to their high reactivity, and therefore, numerical modelling is an effective tool to study ambient amines. However, the contribution of marine biological emissions (MBE), an important source of methylamines (MA), has been insufficiently investigated in the current emission inventory. Therefore, this study utilized satellite data such as Sea Surface Temperature (SST), Chlorophyll-a (Chla), Sea Surface Salinity (SSS) and model simulation data (Wind Speed, WS) to establish a more reasonable MBE inventory of amines. Spatial and temporal distribution of methylamine emissions indicates that MBE fluxes of monomethylamine (MMA) and trimethylamines (TMA) can be comparable with or even higher than that of terrestrial anthropogenic emissions (AE), while for dimethylamines (DMA), the ocean acts as a sink. The method used in this study can better reflect the exchange direction of amines between ocean and atmosphere, and reflect the emission characteristics of different amines. From WRF-Chem simulation results, the concentration of amines in the coastline was found to increase significantly due to the contribution of MBE. Wind and Chla were potentially the most important factors affecting MBE fluxes. WS is directly used in the calculation of ocean-atmosphere exchange coefficient Kg, and the direction of the prevailing winds in different seasons affects the area of influence of the MBE. Chla indirectly influences the calculation results of exchange flux by affecting the calculation of pH. In addition, the emission fluxes and spatial distribution of AE and wet deposition also affect the simulation of amines.
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