Atmospheric inputs of volcanic iron around Heard and McDonald Islands, Southern ocean

Abstract

Increased atmospheric Fe loading and solubility was attributed to emissions from Heard Island volcano (Kerguelen plateau), emphasizing the need for models to consider volcanoes as a source of aeolian Fe to remote oceanic regions.

Southern Ocean Phytoplankton Stimulated by Wildfire Emissions and Sustained by Iron Recycling

“…These anomalies agree with in situ chl and b bp anomalies observed by biogeochemical Argo floats profiling the eastern bloom region (Figure S5 and Text S2 in Supporting Information ; Tang et al., 2021) and are consistent with satellite‐detected biological responses to purposeful and natural OIF (Westberry et al., 2013). The anomalies also exceeded anomalies observed after volcanic ash fertilization in the North Pacific (Westberry et al., 2019), likely due to higher soluble iron concentrations in wildfire emissions compared to volcanic ash (Hamilton et al., 2022; Ito et al., 2019; Perron et al., 2021) as well as stronger iron deficiency in the South Pacific compared to the North Pacific (Abadie et al., 2017; Zheng & Sohrin, 2019).…”

“…Primary productivity in the Southern Ocean is seasonally limited by iron and light (Boyd, 2002; Martin et al., 1990; Mitchell et al., 1991; Ryan‐Keogh et al., 2018). Supply of bioavailable iron to surface waters is largely dependent on upwelling of iron‐rich subsurface waters (Schallenberg et al., 2018; Tagliabue et al., 2014) and deposition of iron‐bearing aerosols from dust storms (Jickells et al., 2005; Mahowald et al., 2005), wildfires (Mallet et al., 2017; Perron et al., 2020, 2022), and volcanic eruptions (Olgun et al., 2011; Perron et al., 2021). Iron recycling is a secondary yet substantial source of bioavailable iron and allows phytoplankton to maintain standing stocks for up to several weeks without new external supply of iron (Bowie et al., 2001; Boyd et al., 2015; Laglera et al., 2017).…”

Subaerial volcanism is a potentially major contributor to oceanic iron and manganese cycles

“…There are multiple ways through which volcanoes may affect the climate on a range of timescales from hours to millions of years 9,10 . Volcanism can induce global climatic cooling via radiative forcing from sulfate injection 11 , but also potentially by oceanic fertilisation associated with the input of nutrient-rich ash [12][13][14][15] . Although experimental evidence demonstrates the release of nutrients from freshly-deposited ash (defined as all airborne volcanic particles under 2 mm in diameter) in surface seawater 16 , the impacts of this process appear to be restricted to transient algal blooms observed directly after eruptions 17,18 .…”