Deep diving scientists discover bubbling CO2 hotspot they call „Soda Springs“ next to thriving coral reefs

A researcher collects gas samples at Soda Springs in the Philippines. Photo: University of Texas at Austin Jackson School of Geosciences

A nearby volcano in the Verde Island Passage between the Philippines’ islands vents out gases through cracks in the ocean floor

Diving 200 feet under the ocean surface to conduct scientific research can lead to some interesting places. For Professor Bayani Cardenas from Jackson School of Geosciences at the University of Texas at Austin, it placed him in the middle of a champagne-like environment of bubbling carbon dioxide with off-the-chart readings of the greenhouse gas. Cardenas discovered the region – which he calls „Soda Springs“ – while studying how groundwater from a nearby island could affect the ocean environment of the Verde Island Passage in the Philippines.

The passage is one of the most diverse marine ecosystems in the world and is home to thriving coral reefs.

The amazing bubbling location, which Cardenas captured on video, is not a climate change nightmare. It is linked to a nearby volcano that vents out the gases through cracks in the ocean floor and has probably been doing so for decades or even millennia.

Therefore, Cardenas said that the high CO2 levels could make Soda Springs an ideal spot for studying how coral reefs may cope with climate change. The site also offers a fascinating setting to study corals and marine life that are making a home among high levels of CO2.

The scientists from UT and institutions between the Philippines’ islands and the Netherlands measured CO2 concentrations as high as 95,000 parts per million (ppm), more than 200 times the concentration of CO2 found in the atmosphere. The readings range from 60,000 to 95,000 and are potentially the highest ever recorded in nature. The CO2 levels fall quickly away from the seeps as the gas is diluted in the ocean, but it still creates an elevated CO2 environment along the rest of the coastline of the Calumpan Peninsula, with levels in the 400 to 600 ppm range.

Cardenas is a geologist and discovered Soda Springs while researching whether groundwater from the nearby land could be discharging into the submarine ocean environment. This phenomenon has been generally ignored by scientists looking at the water cycle, he said: „It’s an unseen flux of water from land to the ocean which is hard to quantify. It’s not like a river where you have a delta and you can measure it.“

Along with the CO2 bubbles, the team also found hotspots in the seafloor where groundwater was being discharged into the ocean. This is significant, said Cardenas, because the connection between the groundwater and ocean means that there is a pathway for pollutants from the island to make it to the reef system.

This is particularly important for a place like the Philippines where coastal development is booming largely because of ecotourism driven by the nearby reefs, but the communities almost always depend on septic tanks instead of modern sewage systems.

Cardenas has been scuba diving since his college days in the Philippines. Training in deep diving has allowed him to open up a portion of the ocean that is rarely studied. „It’s really a big part of the ocean that is left unexplored because it’s too shallow for remotely operated vehicles and is too deep for regular divers,“ he said.

Geophysical Research Letters

UT Austin


(28.01.2020, USA: 01.28.2020)