BENGALURU: Nature has a unique way of synchronisation and maintaining a sustainable equilibrium within its own ecosystem. Deserts, which are considered barren and a challenge for human habitation, contribute significantly in making oceans productive and turning them into carbon sinks with their dust. The desert dust carries rich micronutrients and trace metals that help in carbon sequestration.
In a first-of-its-kind study conducted on the basis of satellite imagery and isotopic work by the CSIR-National Institute of Oceanography (NIO), Dona Paula, Goa, in 2020, ocean scientists discovered that the dust particles collected over the Arabian Sea confirmed the influence of dust storms from Saudi Arabia and Iran. “Dust particles carried by the wind over the deserts are an essential contributor of nutrients and trace metals to the microscopic surface-dwelling plants -- the phytoplankton -- in the global ocean, which in turn naturally help in controlling atmospheric CO2,” Director of CSIR-NIO and ocean scientist Sunil Kumar Singh told TNIE.
He said that despite its significance, the overall impact of dust deposition on the Arabian Sea is not well understood and the biogeochemical modellers often rely upon qualitative parameterisation of dust source regions -- from Saudi Arabia, Iran to Thar desert -- based on satellite remote sensing products. According to ocean researchers, the process of dust transport and its impact on the Arabian Sea occurs during summer. It was believed that the air parcels transported to the Arabian Sea during winter are mainly dominated by the smoke particles (that is, soot, sulphates and nitrates).
“Although surrounded by several land masses, it was not clear which dust source is most likely contributing to mineral aerosols over the Arabian Sea during winter. It was during one of our expeditions onboard Research Vessel Sindhu Sadhana, as part of the Indian effort towards the GEOTRACES Programme that the NIO researchers encountered two specific dust storm events over the Arabian Sea,” Singh said.
GEOTRACES is an international programme, which aims to improve the understanding of biogeochemical cycles and large-scale distribution of trace elements and their isotopes in the marine environment. Scientists from 35 countries, including India, have been involved in the programme, which is designed to study all major global ocean basins.
“The first dust storm sampled over the Arabian Sea on January 27, 2020, was found to have originated from Saudi Arabia. In contrast, the second dust storm sampled after two weeks, on February 10, was found to have been from Iran and the Indo-Gangetic Plain,” he said.
‘Dust particles major source of minerals to sea’
“Interestingly , the isotope signature of the first storm resembled the other dust samples collected over the central Arabian Sea, thus signifying the importance of dust outbreaks from the Arabian Peninsula contributing mineral dust during winter,” Sunil Kumar Singh said.
The study highlights the importance of dust storms in the Middle East on the Arabian Sea during winter. “These dust particles are the major source of minerals and nutrients to the sea fuelling productivity in the region and helping sequester the atmospheric CO2,” he said.
The southern region of the Antarctic Ocean, which is around 30% of the global ocean, is called the desert of the ocean because it has low productivity. “Dust comes from land and doesn’t reach this region. Scientists are planning to do iron fertilisation through spraying tonnes of desert dust into the ocean to help increase productivity and carbon sequestration,” Singh said.