Manganese (Mn) is a key cofactor in enzymes responsible for lignin decay (mainly Mn peroxidase), regulating the rate of litter degradation and carbon (C) turnover in temperate and boreal forest biomes.While soil Mn is mainly derived from bedrock, atmospheric Mn could also contribute to soil Mn cycling, especially within the surficial horizon, with implications for soil C cycling. However, quantification of the atmospheric Mn cycle, which comprises emissions from natural (desert dust, sea salts, volcanoes, primary biogenic particles, and wildfires) and anthropogenic sources (e.g. industrialization and land-use change due to agriculture) transport, and deposition into the terrestrial and marine ecosystem, remains uncertain. Here, we use compiled emission datasets for each identified source to model and quantify the atmospheric Mn cycle with observational constraints. We estimated global emissions of atmospheric Mn in aerosols (<10 µm in aerodynamic diameter) to be 1500 Gg Mn yr-1. Approximately 32% of the emissions come from anthropogenic sources. Deposition of the anthropogenic Mn shortened soil Mn “pseudo” turnover times in surficial soils about 1-m depth (ranging from 1,000 to over 10,000,000 years) by 1-2 orders of magnitude in industrialized regions. Such anthropogenic Mn inputs boosted the Mn-to-N ratio of the atmospheric deposition in non-desert dominated regions (between 5×10-5 and 0.02) across industrialized areas, but still lower than soil Mn-to-N ratio by 1-3 orders of magnitude. Correlation analysis revealed a negative relationship between Mn deposition and topsoil C density across temperate and (sub)tropical forests, illuminating the role of Mn deposition in these ecosystems.

As the largest natural source of sulfur-containing gases into the atmosphere, ocean organism-derived dimethyl sulfide (DMS) has been considered to play a critical role in the Earth’s climate system. Yet there are great uncertainties in modeling the spatiotemporal variations of DMS and incomplete knowledge of influencing factors in different oceanic regions. Moreover, little is known about the future change of global DMS, which limits our understanding of the feedback of marine ecosystem to climate change. Here we develop an artificial neural network model and combine data mining approaches to address these issues. Phytoplankton biomass and salinity are currently predominant factors associated with DMS variability in the coastal and Arctic regions, respectively. In the mid- and low-latitude open oceans, nutrients and temperature are also crucial factors in addition to radiation and mixed layer depth, and their relationships with DMS show reversals when passing certain thresholds. Although the global average DMS concentration and emission slightly decline from 2005 to 2100, they may change considerably in specific regions. In contrast to the DMS decreases in the low-latitudes mainly related with phosphate reduction and temperature rise and in the North Atlantic subpolar gyre attributed to salinity decline, warming will cause DMS increase in the Southern Ocean and sea ice loss will dramatically enhance DMS emission in the Arctic. Although the global negative feedback loop between oceanic DMS and climate may not operate, the future spatial redistribution of DMS may lead to the change in cloud cover pattern and significantly affect regional climate.

Marine biological activities make substantial influences on aerosol composition and properties. The eastern China seas are highly productive with significant emissions of biogenic substances. Air mass exposure to chlorophyll a (AEC) can be used to indicate the influence of biogenic source on the atmosphere to a certain degree. In this study, the 12-year (2009–2020) daily AEC were calculated over the eastern China seas showing the spatial and seasonal patterns of marine biogenic influence intensity are co-controlled by surface phytoplankton biomass and boundary layer height. The AEC was linearly correlated with aerosol methanesulfonate (MSA) in each of three sub-regions, and the constructed parameterization scheme was applied to simulate the spatiotemporal variation of marine biogenic MSA. This AEC-based approach with observation constraints provides a new insight into the distribution of marine biogenic aerosols which may become increasingly important with the decline of terrestrial input to the studied region.

Haptophytes and Dinoflagellates are two cosmopolitan algae associated with dimethylsulfoniopropionate (DMSP) synthesis, which regulates the marine biogenic flux of dimethylsulfide (DMS) to the atmosphere and subsequently affects marine aerosols. Attempting to reveal the potential impact of atmospheric deposition on the growth of main DMSP producers, four bioassay experiments were conducted in the western North Pacific (WNP) by adding aerosols, nutrients and trace metals. Our results showed that the percentage of main DMSP producers increased substantially from coastal regions (<1%) to the open ocean (~17%) with the dominance of Dinophyceae and Haptophyceae, respectively. Aerosol additions largely increased the percentage of DMSP species in the open WNP. Specifically, atmospheric DIN and soluble Cu, and Fe promoted Chrysochromulina, and Phaeocystis and E. huxleyi, respectively. It is very likely that atmospheric deposition could lift the relative abundance of main DMSP producers in the vast oligotrophic oceans and contribute to the climate change.