Abstract. Molecular composition and abundance of sugars and secondary organic aerosols (SOA) from biogenic sources over the East China Sea were investigated based on gas chromatography–mass spectrometry. Biogenic SOA tracers and sugars exhibit higher levels in the samples affected by continental air masses, demonstrating the terrestrial outflows of organic matter to the East China Sea. Glucose was the dominant sugar species (0.31–209, 18.8 ng m−3), followed by mannitol – a fungal spore tracer. All sugar compounds show generally higher average concentrations in the nighttime than in the daytime. 3-Methyl-1,2,3-butanetricarboxylic acid, one higher generation photooxidation tracer of monoterpene SOA, was found to be the most abundant species among measured biogenic SOA markers, suggesting the input of aged organic aerosols through long-range transport. Fungal-spore-derived organic carbon (OC) was the biggest contributor to total OC (0.03 %–19.8 %, 3.1 %), followed by sesquiterpene-derived secondary OC (SOC), biomass-burning-derived OC, and monoterpene- and isoprene-derived SOC. Larger carbon percentages of biogenic primary OCs and SOCs in total OC presented in the terrestrially influenced aerosols indicate significant contributions of continental aerosols through long-range transport. Positive matrix factorization results illustrate that the secondary nitrate and biogenic SOA, biomass burning, and fungal spores were the main sources of OC in marine aerosols over the East China Sea, again highlighting the importance of the Asian continent as a natural emitter of biogenic organic aerosols together with anthropogenic aerosols over the coastal marine atmosphere.

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Abstract. A three-dimensional coupled physicalbiogeochemical model was used to simulate and examine temporal and spatial variability of sea surface pCO 2 in the Gulf of Mexico (GoM). The model was driven by realistic atmospheric forcing, open boundary conditions from a dataassimilative global ocean circulation model, and observed freshwater and terrestrial nutrient and carbon input from major rivers. A 7-year model hindcast (2004)(2005)(2006)(2007)(2008)(2009)(2010) was performed and validated against ship measurements. Model results revealed clear seasonality in surface pCO 2 and were used to estimate carbon budgets in the Gulf. Based on the average of model simulations, the GoM was a net CO 2 sink with a flux of 1.11 ± 0.84 × 10 12 mol C yr −1 , which, together with the enormous fluvial inorganic carbon input, was comparable to the inorganic carbon export through the Loop Current. Two model sensitivity experiments were performed: one without biological sources and sinks and the other using river input from the 1904-1910 period as simulated by the Dynamic Land Ecosystem Model (DLEM). It was found that biological uptake was the primary driver making GoM an overall CO 2 sink and that the carbon flux in the northern GoM was very susceptible to changes in river forcing. Large uncertainties in model simulations warrant further process-based investigations.

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