preprints.org > environmental and earth sciences > environmental science > doi: 10.20944/preprints202401.0570.v1

Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Version 1 : Received: 8 January 2024 / Approved: 8 January 2024 / Online: 8 January 2024 (07:20:49 CET)

Dust storms and wildfires occur frequently in southeastern Australia. Their effects on ecology, environment and population exposure have been the focus of many studies recently. Dust storms do not emit ground-sequestered carbon but wildfires emit significant quantities of carbon into the atmosphere. However, both natural events promote phytoplankton growth in water bodies because carbon, and other trace elements such as iron, deposit on the surface water of oceans. Carbon dioxide is reabsorbed by phytoplankton via photosynthesis. The carbon balance cycle due to dust storms and wildfires are not well known. Recent studies on the carbon emission of the 2019-2020 summer wildfires in eastern Australia indicated that this megafire event emitted approximately 715 million tonnes of CO2 (195 Tg C) into the atmosphere from burned forest areas. The projected increase in the frequency of wildfires due to climate change alters what was a carbon neutral process of reabsorbing emitted carbon by the forests, and subsequently cannot be achieved. With the result of net loss of sequestered carbon to the atmosphere, subsequently further promotes a warming climate. This study focusses on the association of dust storms and wildfires in southeastern Australia with phytoplankton growth in the Tasman Sea due to the February 2019 dust storm event and the 2019-2020 Black Summer wildfires. Central Australia and western New South Wales were the sources of the dust storm emission (11 to 16 February 2019) and the Black Summer wildfires occured along the coast of New South Wales and Victoria (from early November 2019 to early Januaray 2020). The results show the similarities and differences in the deposition of particulate matter, phytoplankton growth and carbon reabsorption patterns in the Tasman Sea from these events. Using WRF-Chem model, during the 5 days dust storm event in February 2019, approximately ~1230 tons of total dust were predicted to be deposited in the Tasman Sea while ~132,000 tons of PM10 were deposited in the early stage of the wildfires from 1 to 8 November 2019.

February 2019 Dust storm; 2019-2020 summer wildfires; Southeast Australia; phytoplankton growth; WRF-Chem model; Southern Ocean; Tasman Sea

Environmental and Earth Sciences, Environmental Science

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