ORCID Profile
0000-0002-4937-2927
Current Organisation
Japan Agency for Marine-Earth Science and Technology
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: American Geophysical Union (AGU)
Date: 02-05-2007
DOI: 10.1029/2006JD007712
Publisher: Springer Science and Business Media LLC
Date: 26-08-2020
DOI: 10.1186/S40645-020-00357-9
Abstract: Mineral dust is the major source of external micro-nutrients such as iron (Fe) to the open ocean. However, large uncertainties in model estimates of Fe emissions and aerosol-bearing Fe solubility (i.e., the ratio of labile Fe (L Fe ) to total Fe (T Fe )) in the Southern Hemisphere (SH) h ered accurate estimates of atmospheric delivery of bioavailable Fe to the Southern Ocean. This study applied an inverse modeling technique to a global aerosol chemistry transport model (IMPACT) in order to optimize predictions of mineral aerosol Fe concentrations based on recent observational data over Australian coastal regions (110°E–160°E and 10°S–41°S). The optimized (a posteriori) model did not only better capture aerosol T Fe concentrations downwind from Australian dust outbreak but also successfully reproduced enhanced Fe solubility (7.8 ± 8.4%) and resulted in much better agreement of L Fe concentrations with the field measurements (1.4 ± 1.5 vs. 1.4 ± 2.3 ng Fe m –3 ). The a posteriori model estimates suggested that bushfires contributed a large fraction of L Fe concentrations in aerosols, although substantial contribution from missing sources (e.g., coal mining activities, volcanic eruption, and secondary formation) was still inferred. These findings may have important implications for the projection of future micro-nutrient supply to the oceans as increasing frequency and intensity of open biomass burning are projected in the SH.
Publisher: Copernicus GmbH
Date: 10-07-2018
DOI: 10.5194/BG-2018-285
Abstract: Abstract. This work reports on the current status of global modelling of iron (Fe) deposition fluxes and atmospheric concentrations and analyses of the differences between models, as well as between models and observations. A total of four global 3-D chemistry-transport (CTMs) and general circulation (GCMs) models have participated in this intercomparison, in the framework of the United Nations Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP) Working Group 38, The Atmospheric Input of Chemicals to the Ocean. The global total Fe (TFe) emissions strength in the models is equal to ~ 72 Tg-Fe yr−1 (38–134 Tg-Fe yr−1) from mineral dust sources and around 2.1 Tg-Fe yr−1 (1.8–2.7 Tg-Fe yr−1) from combustion processes (sum of anthropogenic combustion/biomass burning and wildfires). The mean global labile Fe (LFe) source strength in the models, considering both the primary emissions and the atmospheric processing, is calculated to be 0.7 (±0.3) Tg-Fe yr−1, accounting for mineral dust and combustion aerosols together. The multi model ensemble global TFe and LFe deposition fluxes into the global ocean are calculated to be ~ 15 Tg-Fe yr−1 and ~ 0.3 Tg-Fe yr−1, respectively. The model intercomparison analysis indicates that the representation of the atmospheric Fe cycle varies among models, in terms of both the magnitude of natural and combustion Fe emissions as well as the complexity of atmospheric processing parametrizations of Fe-containing aerosols. The model comparison with aerosol Fe observations over oceanic regions indicate that most models overestimate surface level TFe mass concentrations near the dust source regions and tend to underestimate the low concentrations observed in remote ocean regions. All models are able to simulate the tendency of higher Fe loading near and downwind from the dust source regions, with the mean normalized bias for the Northern Hemisphere (~ 14), larger than the Southern Hemisphere (~ 2.4) for the ensemble model mean. This model intercomparison and model–observation comparison study reveals two critical issues in LFe simulations that require further exploration: 1) the Fe-containing aerosol size distribution and 2) the relative contribution of dust and combustion sources of Fe to labile Fe in atmospheric aerosols over the remote oceanic regions.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 09-07-2021
Abstract: Changing atmospheric acidity alters the delivery of nutrients to the ocean and affects marine productivity and ecology.
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-19425
Abstract: & & 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 (NO& sub& & /sub& & sup& -& /sup& and HNO& sub& & /sub& ) and reduced (NH& sub& & /sub& and NH& sub& & /sub& & sup& +& /sup& ) 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 in idual 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.& &
Publisher: Copernicus GmbH
Date: 09-11-2018
Abstract: Abstract. This work reports on the current status of the global modeling of iron (Fe) deposition fluxes and atmospheric concentrations and the analyses of the differences between models, as well as between models and observations. A total of four global 3-D chemistry transport (CTMs) and general circulation (GCMs) models participated in this intercomparison, in the framework of the United Nations Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP) Working Group 38, “The Atmospheric Input of Chemicals to the Ocean”. The global total Fe (TFe) emission strength in the models is equal to ∼72 Tg Fe yr−1 (38–134 Tg Fe yr−1) from mineral dust sources and around 2.1 Tg Fe yr−1 (1.8–2.7 Tg Fe yr−1) from combustion processes (the sum of anthropogenic combustion/biomass burning and wildfires). The mean global labile Fe (LFe) source strength in the models, considering both the primary emissions and the atmospheric processing, is calculated to be 0.7 (±0.3) Tg Fe yr−1, accounting for both mineral dust and combustion aerosols. The mean global deposition fluxes into the global ocean are estimated to be in the range of 10–30 and 0.2–0.4 Tg Fe yr−1 for TFe and LFe, respectively, which roughly corresponds to a respective 15 and 0.3 Tg Fe yr−1 for the multi-model ensemble model mean. The model intercomparison analysis indicates that the representation of the atmospheric Fe cycle varies among models, in terms of both the magnitude of natural and combustion Fe emissions as well as the complexity of atmospheric processing parameterizations of Fe-containing aerosols. The model comparison with aerosol Fe observations over oceanic regions indicates that most models overestimate surface level TFe mass concentrations near dust source regions and tend to underestimate the low concentrations observed in remote ocean regions. All models are able to simulate the tendency of higher Fe concentrations near and downwind from the dust source regions, with the mean normalized bias for the Northern Hemisphere (∼14), larger than that of the Southern Hemisphere (∼2.4) for the ensemble model mean. This model intercomparison and model–observation comparison study reveals two critical issues in LFe simulations that require further exploration: (1) the Fe-containing aerosol size distribution and (2) the relative contribution of dust and combustion sources of Fe to labile Fe in atmospheric aerosols over the remote oceanic regions.
Publisher: Annual Reviews
Date: 03-01-2021
DOI: 10.1146/ANNUREV-MARINE-031921-013612
Abstract: A key Earth system science question is the role of atmospheric deposition in supplying vital nutrients to the phytoplankton that form the base of marine food webs. Industrial and vehicular pollution, wildfires, volcanoes, biogenic debris, and desert dust all carry nutrients within their plumes throughout the globe. In remote ocean ecosystems, aerosol deposition represents an essential new source of nutrients for primary production. The large spatiotemporal variability in aerosols from myriad sources combined with the differential responses of marine biota to changing fluxes makes it crucially important to understand where, when, and how much nutrients from the atmosphere enter marine ecosystems. This review brings together existing literature, experimental evidence of impacts, and new atmospheric nutrient observations that can be compared with atmospheric and ocean biogeochemistry modeling. We evaluate the contribution and spatiotemporal variability of nutrient-bearing aerosols from desert dust, wildfire, volcanic, and anthropogenic sources, including the organic component, deposition fluxes, and oceanic impacts.
Publisher: Copernicus GmbH
Date: 10-07-2018
Publisher: American Association for the Advancement of Science (AAAS)
Date: 03-05-2019
Abstract: Air pollution creates high Fe solubility in pyrogenic aerosols, raising the flux of biologically essential Fe to the oceans.
No related grants have been discovered for Akinori Ito.