Cites activity causes higher flux of CO2 into ocean
PANAJI
A new study by scientists at CSIR–National Institute of Oceanography (NIO), Goa, shows that periods of glaciation played a key role in boosting volcanic eruptions and hydrothermal activity along mid-ocean ridges (MORs), influencing the release of carbon dioxide into the ocean.
Director of CSIR–NIO, Dona Paula, Prof Sunil Kumar Singh along with researchers Sayantan De and Robin John of CSIR–NIO, analysed a 49,000-year sediment record collected from the Carlsberg Ridge in the Indian Ocean to understand the relationship between glacial–interglacial sea-level changes, volcanism and hydrothermal processes.
Singh said their research demonstrates a clear link between glaciation and volcanism. During glacial periods, increased volcanic activity along hydrothermal ridges intensified hydrothermal circulation, leading to a higher flux of carbon dioxide into the ocean.
He explained that the team reconstructed past hydrothermal activity by studying trace elements and lead (Pb) isotope compositions in ferro-manganese (Fe–Mn) oxyhydroxide coatings found in sediment cores.
According to Singh, this is the first Pb isotope record from Fe–Mn coatings at an active mid-ocean ridge in the Indian Ocean, offering new insights into how sea-level changes influence hydrothermal systems at slow-spreading ridges over thousands of years.
The researchers found that deep-sea sediments along MORs reflect a mix of hydrothermal inputs, volcanic material and debris from land. By analysing trace metals such as cobalt, nickel and chromium, along with Pb isotope ratios in the Fe–Mn coatings, they identified chemical signatures that record the link between glaciation and volcanism.
The study concludes that slow-spreading mid-ocean ridge hydrothermal systems respond strongly to climate-driven sea-level fluctuations. A drop in sea level during glacial periods reduces pressure on the ocean floor, which in turn enhances volcanic eruptions and hydrothermal activity, with long-term impacts on ocean chemistry.
Singh informed that similar increases in hydrothermal flux during glacial low sea levels have been observed at other ocean ridges, including the East Pacific Rise, Juan de Fuca Ridge, Mid-Atlantic Ridge, Central Indian Ridge and the Tianxiu Vent Field of the Carlsberg Ridge.
