Volcanoes Feed the Planet with Nutrients

A powerful volcano last January was followed by
a phytoplankton bloom. What’s the connection?

— Life may depend on nutrients delivered to the surface from deep underground —

Complex life depends on at least 26 chemical elements; some lists are longer. These include the well-known ones like carbon, hydrogen, oxygen and nitrogen, but there are many others. Pressed to name them, college-educated readers and nutrient aficionados might add phosphorus, potassium, sodium, chlorine, iron, copper, zinc, magnesium, manganese and calcium. With a little assistance of a periodic table, they might add a few more. But cobalt? Boron? Selenium? Bromine? Molybdenum? Tin? Yes, these and several other elements are vital in trace amounts either within cells or during manufacture of nutrients.

If Earth formed from a molten mass, and the heavy elements sank to the core or mantle, how did the required cocktail of elements appear on the surface of the Earth?

Volcanoes are one method for rapid special delivery of elements to the biosphere. This was recently demonstrated by one of the most powerful eruptions in recent years: the Hunga-Tonga volcano on January 15, 2022.

Volcano eruption in Tonga Jan 15, 2022. (Earth Observatory satellite, NASA)

Tonga eruption spawns massive phytoplankton bloom (University of Hawaii, 12 Oct 2022).

The ocean turned green within days after the Tonga volcano surprised geologists on January 15. A massive bloom of phytoplankton (photosynthetic bacteria) was flourishing. Scientists estimated the bloom covered an area 40 times the size of the island of Oahu, Hawaii. Was this a cause-and-effect event? Yes, say researchers from the University of Hawaii.

UH Mānoa’s School of Ocean and Earth Science and Technology (SOEST)-led team, analyzed satellite images of various kinds—true color, emission of red and infrared radiation, and light reflection at the sea surface—and determined that the deposition of volcanic ash was likely the most important source of nutrients responsible for phytoplankton growth.

“Even though the Hunga Tonga-Hunga Haʻapai eruption was submarine, a large plume of ash reached a height of tens of kilometers into the atmosphere,” said Benedetto Barone, lead author of the study and research oceanographer at the Center for Microbial Oceanography: Research and Education (C-MORE) in SOEST. “The ash fallout supplied nutrients that stimulated the growth of phytoplankton, which reached concentrations well beyond the typical values observed in the region.”

The finding was published in an open-access AGU paper in Geophysical Research Letters on September 3, 2022: Barone et al., “Satellite Detection of a Massive Phytoplankton Bloom Following the 2022 Submarine Eruption of the Hunga Tonga-Hunga Haʻapai Volcano.”

The volcano could have delivered iron (Fe), but a more important element may have been phosphorus (P). Iron is already plentiful in crustal rocks, but phosphorus is harder to come by. That’s why the search for phosphorus has been so important for agricultural fertilizers. Phosphorus is a key element in many biomolecules, including ATP and DNA. The paper says,

But how much ash would be required to sustain the growth of a phytoplankton bloom equivalent to 1 mg m⁻³ of chlorophyll a? A calculation of the nutrient flux through this process can be obtained by using the rate of nutrient release in the top 50 m from the deposition of subduction zone volcanic ash reported by Duggen et al. (2007). Assuming a Redfield stoichiometry for the synthesis of phytoplankton biomass and 133 moles of P per mole of Fe (Ho et al., 2003), the release rates reported by Duggen et al. (2007) indicate that P would be depleted before N and Fe. Phytoplankton growth of 1 mg chlorophyll a m⁻³ with a ratio of 100 g of carbon per g of chlorophyll a would then require the P supplied by an ash deposition of 20–197 mm. These depositional fluxes are very likely to have been achieved considering the height of the ash plume observed during the HTHH eruption (Biass et al., 2019; Hurst & Davis, 2017) and publically available news reports of distal ash observations on Tongatapu.

Apparently the plankton were able to incorporate the phosphorus in its elemental form directly from the ash falling onto the seawater. If so, they got it special delivery in one day. And once they used it in their biomolecules, the element would also have been available to other animals that feed on the plankton.

“The Earth is the Lord’s” (Psalm 24:1). We are merely stewards.
Illustration courtesy Santa Clarita Magazine

As I wrote in Evolution News on 7 Sept 2022, phosphorus forms a test case for Michael Denton’s “Privileged Species” hypothesis: i.e., that the universe, the Earth and the laws of nature appear finely tuned not only for life, but for complex beings the size of humans. Denton does not credit the God of the Bible for all the fine tuning, but finds it remarkable that all the elements needed for life are available where needed. Phosphorus, being essential yet harder to erode from crustal rocks, could be a limiting factor. Well, our Creator thought of everything: even volcanoes to deliver the vital nutrients we need!

The fact that living things never seemed starved for phosphorus throughout the history of life (think rainforests, giant sauropods and whales, coral reefs) in every biome suggests that God provided enough phosphorus for us through geological processes as well as biological systems. That took foresight—a mark of intelligent design.

Recommended Resource: Denton’s book The Miracle of Man, the capstone of his books on fine-tuning for complex life, is loaded with fascinating information about just how many remarkable “coincidences” came together on the Earth for the benefit of man. See also video clips at the link. Denton accepts deep time and possibly some form of biological evolution, but Biblical creationists can find page after page of information that can only be explained by a loving Savior who created us to thrive on God’s green Earth.

There’s also a playlist of beautiful videos at the Discovery Institute’s YouTube channel featuring Michael Denton’s work.