Description: Atmospheric deposition of long-range transport of anthropogenic reactive nitrogen (Nr, mainly comprised of NHx , NOy and water-soluble organic nitrogen, WSON) from continents may have profound impact on marine biogeochemistry. However, surface ocean dissolved organic nitrogen (DON) may also contribute to aerosol WSON in the overlying atmosphere. Despite the importance of off-continent dispersion and Nr interactions at the atmosphere–ocean boundary, our knowledge of the sources of various nitrogen species in the atmosphere over the open ocean remains limited due to insufficient observations. We conducted two cruises in the spring of 2014 and 2015 from the coast of China through the East China seas (ECSs, i.e. the Yellow Sea and East China Sea) to the open ocean (i.e. the north-western Pacific Ocean, NWPO). Concentrations of water-soluble total nitrogen (WSTN), NO3- and [NH4]+ , as well as the 15N of WSTN and NO3- in marine aerosol, were measured during both cruises. In the spring of 2015, we also analysed the concentrations and 15N of [NO3]- and the DON of surface seawater (SSW; at a depth of 5m) along the cruise track. Aerosol [NO3]- , [NH4]+ and WSON decreased logarithmically (1–2 orders of magnitude) with distance from the shore, reflecting strong anthropogenic emission sources of [NO3]-, [NH4]+ and WSON in China. Average aerosol [NO3]- and [NH4]+ concentrations were significantly higher in 2014 (even in the remote NWOP) than in 2015 due to the stronger wind field in 2014, underscoring the role of the Asian winter monsoon in the seaward transport of anthropogenic [NO3]- and [NH4]+ . However, the background aerosol WSON over the NWPO in 2015 (13.3±8.5 nmol/m3 was similar to that in 2014 (12.2±6.3 nmol/m3, suggesting an additional non-anthropogenic WSON source in the open ocean. Obviously, marine DON emissions should be considered in model and field assessments of net atmospheric WSON deposition in the open ocean. This study contributes information on parallel isotopic marine DON composition and aerosol Nr datasets, but more research is required to explore complex Nr sources and deposition processes in order to advance our understanding of anthropogenic influences on the marine nitrogen cycle and nitrogen exchange at land–ocean and atmosphere–ocean interfaces.

Description: With the rapid expansion of maritime traffic, increases in air emissions from shipping have exacerbated numerous environmental issues, including air pollution and climate change. However, the effects of such emissions on marine biogeochemistry remain poorly understood. Here, we collected ship-emitted particles (SEPs) from the stack of a heavy-oil-powered vessel using an onboard emission test system and investigated the impact of SEPs on phytoplankton growth over the northwest Pacific Ocean (NWPO). In SEP microcosm experiments conducted in oceanic zones with different trophic statuses, the phytoplankton response, as indicated by chlorophyll a (Chl a), has been shown to increase with the proportion of SEP-derived nitrogen (N) relative to N stocks (PSN) in baseline seawater, suggesting that SEPs generally promote phytoplankton growth via N fertilisation. Simulations using an air quality model combined with a ship emission inventory further showed that oxidised N (NOx) emissions from shipping contributed ~43% of the atmospheric N deposition flux in the NWPO. Air emissions from shipping (e.g. NOx and sulphur dioxide) also indirectly enhanced the deposition of reduced N that existed in the atmosphere, constituting ~15% of the atmospheric N deposition flux. These results suggest that the impact of airborne ship emissions on atmospheric N deposition is comparable to that of land-based emissions in the NWPO. Based on the ship-induced PSN in surface seawater calculated by modeling results and World Ocean Atlas 2013 nutrient dataset, and the well-established quantitative relationship between Chl a and PSN obtained from microcosm experiments, we found a noticeable change in surface Chl a concentrations due to N deposition derived from marine traffic in the NWPO, particularly in the coastal waters of the Yellow Sea and open oceans. This work attempts to establish a direct link between marine productivity and air emissions from shipping.

Description: This paper studies the inter-annual precipitation variations in different regions of East Asia from oceans to interior areas in China during 1979 – 2012. The results computed by Empirical Orthogonal Functions (EOF) demonstrate that the annual precipitation changes are mainly related to the El Niño-Southern Oscillation, East Asian summer monsoon and aerosols. We also found that the increased Sea surface temperature (SST) could explain the precipitation changes over the Northwest Pacific in the dry season (Oct. – May) and the East China Sea and the South China Sea in the rainy season (Jun. – Sep.). The precipitation changes over the ocean unexplained by SST were likely due to the water vapor transport dominated by dynamic factors. With the increased SST, the moisture transported from oceans to interior land was likely redistributed and caused the complicated regional variability of precipitation. Moreover, the impacts of aerosols on cloud and precipitation varied with different pollution levels and different seasons. Scientific Reports 4 doi: 10.1038/srep05693