ALBERT

Description: Reaction with iodide (I-) at the sea surface is an important sink for atmospheric ozone, and causes sea-air emission of reactive iodine which in turn drives further ozone destruction. To incorporate this process into chemical transport models, improved understanding of the factors controlling marine iodine speciation, and especially sea-surface iodide concentrations, is needed. The oxidation of I- to iodate (IO3-) is the main sink for oceanic I-, but the mechanism for this remains unknown. We demonstrate for the first time that marine nitrifying bacteria mediate I- oxidation to IO3-. A significant increase in IO3- concentrations compared to media-only controls was observed in cultures of the ammonia-oxidising bacteria Nitrosomonas sp. (Nm51) and Nitrosoccocus oceani (Nc10) supplied with 9-10 mM I-, indicating I- oxidation to IO3-. Cell-normalised production rates were 15.69 (+/- 4.71) fmol IO3- cell(-1) d(-1) for Nitrosomonas sp., and 11.96 (+/- 6.96) fmol IO3- cell(-1) d(-1) for Nitrosococcus oceani, and molar ratios of iodate-to-nitrite production were 9.2 +/- 4.1 and 1.88 +/- 0.91 respectively. Preliminary experiments on nitrite-oxidising bacteria showed no evidence of I- to IO3- oxidation. If the link between ammonia and I oxidation observed here is representative, our ocean iodine cycling model predicts that future changes in marine nitrification could alter global sea surface I fields with potential implications for atmospheric chemistry and air quality.

Description: Highlights • Tephra are abundant in NE North America, with 36 unique units deposited between ∼14,000 and the present day. • Source volcanoes are in the Cascades, Alaska, Kamchatka, Kuriles and potentially Japan. • Updated Bayesian modelled ages are presented for key proximal correlative eruptions and newly described tephra. • The tephra link paleoenvironmental records from this region to the Far East, Greenland and Europe. • Correlated source eruption volumes vary widely; this alone cannot explain recorded ash distribution trends. Lakes and bogs in northeastern North America preserve tephra deposits sourced from multiple volcanic systems in the Northern Hemisphere. However, most studies of these deposits focus on specific Holocene intervals and the latest Pleistocene, providing snapshots rather than a full picture. We combine new data with previous work, supplemented by a broad review of the characteristics and ages of potential source regions and volcanoes, to develop the first composite tephrostratigraphic framework covering the last ∼14,000 years for this region. We report new cryptotephra records from three ombrotrophic peat bogs—Irwin Smith (Michigan), Bloomingdale (New York), and Sidney Bog (Maine)—as well as new analyses and age models from previously reported sites, Nordan's Pond Bog (Newfoundland) and Thin-Ice Pond (Nova Scotia). A new tephra (Iliinsky) from the NGRIP and GRIP ice cores is also presented as it can be correlated to new data from these terrestrial records and helps validate radiocarbon age models. We identify 21 new tephra in addition to the 15 already known, several of which cover the entire region – the White River Ash east, Newberry Pumice, Ruppert (NDN-230), and Mazama. For the first time we find Mount St. Helens Yn (ca. 3660 cal yr BP) and a set P tephra (∼3000–2550 cal yr BP), and confirm the presence of Jala Pumice from Volcan Ceboruco, Mexico, and KS1 from Ksudach volcano, Kamchatka. We describe new “ultra-distal” tephra, including the early Holocene KS2 eruption, and propose correlations to volcanoes Iliinsky and Shiveluch of Kamchatka, and Ushishir of the Kurile Islands. Not all of these tephra represent large eruptions, with several plausible correlations to sub-Plinian events. Using Bayesian age-modeling, we present new age estimates for the newly described tephra, for tephra with previously poor age control, and for several proximal correlatives. Overall, we demonstrate northeastern North America's importance for providing transcontinental linkages between paleoenvironmental records and providing insights into ash distribution from different styles and sizes of eruptions.

Description: This chapter reviews Japan’s hydrogen strategy with a particular focus on its international elements. It begins by outlining Japan’s international commitment to reduce economy-wide greenhouse gas emissions. The chapter then reviews Japan's domestic policy settings designed to support the deployment of hydrogen in power generation, transport, and industrial uses. The chapter then reviews the strategy that the government is using to enable the development of international supply chains to enable the required imports to satisfy projected hydrogen use in the country. It outlines bilateral technology partnerships and international activities within multilateral forums. It concludes with a short discussion of the geopolitical implications of Japan's hydrogen strategy. Japan has been at the forefront of global efforts to increase the role of hydrogen and ammonia as an option for supporting decarbonization. Japan’s government is positioning hydrogen to play a large role in its overall decarbonisation strategy in support of its mid-century, net zero emissions reduction goal. In this context, the Japanese government is supporting the development of technologies on both the supply and demand side, informed by its understanding of feasible decarbonization pathways domestically and the industrial policy opportunities it has identified to promote Japan's technological leadership. Key features of Japan’s strategy are the central focus on the need to import hydrogen and ammonia and the emphasis domestically on the use of hydrogen and ammonia co-combustion in existing thermal power generation as a transition technology, which is not emphasised in other countries’ national hydrogen strategies. In addition, the Japanese government is championing hydrogen and ammonia internationally through forums such as AZEC, which includes proposing ammonia as a technology option for reducing emissions from the power sector in the Asia-Pacific. A key near-term focus on the supply-side is testing the feasibility of different technology options for hydrogen transport, based on the strong emphasis on hydrogen and ammonia imports within Japan’s hydrogen strategy. Coupled with the potential for exporting technologies for hydrogen use, this suggests that new patterns of trade and investment may emerge, although there remain crucial questions about commercial feasibility in addition to technical challenges. Indeed, Japan’s hydrogen strategy is predicated on the ability to build international supply chains at scale. These are currently being enabled by public investment in early-stage projects. These testing different technology options to enable the export of hydrogen to Japan to support domestic decarbonization. Another challenge lies in unlocking hydrogen demand given that processes using hydrogen and ammonia remain more expensive than alternatives in most cases. A case in point is FCVs, in which consumer demand remains far lower than envisioned. In response, the Japanese government is developing a series of policies to reduce the gap between hydrogen and ammonia and best available technologies. The revised 2023 NHS also signalled a shift towards emphasising Japan’s technology leadership in fuel cells and taking a more neutral approach towards end-use sectors. We can expect Japan’s national hydrogen strategy to continue to develop in response to the effectiveness of policies implemented domestically and internationally to increase the demand for, and supply of hydrogen and associated vectors.