Changing atmospheric acidity as a modulator of nutrient deposition and ocean biogeochemistry
- 1Universtiy of East Anglia, School of Environmental Sciences, Norwich, United Kingdom of Great Britain and Northern Ireland (alex.baker@uea.ac.uk)
- 2Environmental Chemical Processes Laboratory (ECPL), Department of Chemistry, University of Crete, Heraklion, Greece
- 3Center for Studies of Air Quality and Climate Change, Institute for Chemical Engineering Sciences, Foundation for Research and Technology Hellas, Patras, Greece
- 4Laboratory of Atmospheric Processes and their Impacts (LAPI), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- 5Earth and Ocean Sciences, National University of Ireland, Galway, Ireland
- 6Departments of Oceanography and Atmospheric Sciences, Texas A&M University, College Station, TX, USA
- 7Department of Earth and Environmental Sciences, Rutgers University, Newark, USA
- 8Laboratoire d'Océanographie de Villefranche (LOV), UMR7093, CNRS-INSU-Université Paris 6, Villefranche sur Mer, France
- 9Yokohama Institute for Earth Sciences, JAMSTEC, Yokohama, Kanagawa, Japan
- 10Department of Earth and Atmospheric Sciences, Cornell University, Ithaca NY, USA
- 11Department of Ocean Systems, Royal Netherlands Institute for Sea Research, Den Burg, The Netherlands
- 12Atmospheric Physics and Chemistry Group, National Observatory of Athens, Athens, Greece
- 13Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
- 14Geosciences Division, Physical Research Laboratory, Ahmedabad, India
- 15Department of Earth, Ocean & Atmospheric Science, Florida State University, Tallahassee, USA
- 16Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden
Anthropogenic emissions of nitrogen and sulphur oxides and ammonia have altered the pH of aerosol, cloud water and precipitation, with significant decreases over much of the marine atmosphere. Some of these emissions have led to an increased atmospheric burden of reactive nitrogen and its deposition to ocean ecosystems. Changes in acidity in the atmosphere also have indirect effects on the supply of labile nutrients to the ocean. For nitrogen, these changes are caused by shifts in the chemical speciation of both oxidized (NO3- and HNO3) and reduced (NH3 and NH4+) forms that result in altered partitioning between the gas and particulate phases that affect transport. Other important nutrients, notably iron and phosphorus, are impacted because their soluble fractions increase due to exposure to low pH environments during atmospheric transport. These changes affect not only the magnitude and distribution of individual nutrient supply to the ocean but also the ratios of nitrogen, phosphorus, iron and other trace metals in atmospheric deposition. Since marine microbial populations are sensitive to nutrient supply ratio, the consequences of atmospheric acidity change include shifts in ecosystem composition in addition to overall changes in marine productivity. Nitrogen and sulphur oxide emissions are decreasing in many regions, but ammonia emissions are much harder to control. The acidity of the atmosphere is therefore expected to decrease in the future, with further implications for nutrient supply to the ocean.
This presentation will explore the impact of increased atmospheric acidity since the Industrial Revolution, and the projected acidity decreases, on atmospheric nutrient supply and its consequences for the biogeochemistry of the ocean.
How to cite: Baker, A., Kanakidou, M., Nenes, A., Croot, P., Duce, R., Gao, Y., Guieu, C., Ito, A., Jickells, T., Mahowald, N., Middag, R., Myriokefalitakis, S., Perron, M., Sarin, M., Shelley, R., and Turner, D.: Changing atmospheric acidity as a modulator of nutrient deposition and ocean biogeochemistry, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19425, https://doi.org/10.5194/egusphere-egu2020-19425, 2020.
