Acidification of ocean waters due to gases released by asteroid impacts 66 million years ago was the major cause of the last great mass extinction and not the cessation of photosynthesis because of created darkness, as previously believed.
This is reflected in a study conducted by universities in the US, UK and Germany with the participation of researchers at the University of Aragon Environmental Sciences (IUCA) of the Spanish University of Zaragoza, Laia Alegret, and published in the scientific journal Monday Proceedings of the National Academy of Sciences of the USAA (PNAS).
A Spanish paleontologist contributed to the first measurement of surface water pH after the asteroid hit the Mexican Yucatan Peninsula at the end of the Cretaceous, Unizar said in a press release.
Remains of asteroid impact in Yucatan. EFE / Gerta Keller
Acidification, which results from the emission of gases into the atmosphere, This is one of the major consequences of the current climate crisis, which also lowers the pH of the marine property with great impact on marine life.
The paper confirms the hypothesis of Alegret, a specialist in the study of microscopic fossils and geochemical analyzes, that the oceans absorb a third of carbon dioxide (CO2) emissions into the atmosphere, which helps regulate the climate, capturing excess heat
However, this process also has side effects, such as lowering the pH (acidity level) of water, which alters the fixation of calcium carbonate (CaCO3) in skeletons of many species, and can even accelerate climate change, explains the Spanish university.
The effect of said asteroid it captured almost 70% of the planet's species and ended the dominance of large dinosaurs by earthly means. In the oceans, large reptiles such as Mosasaur have disappeared, as well as much of the calcareous plankton that lived in surface waters.
The fossilized fish are stacked on top of each other, suggesting that they were thrown ashore and died stranded in the sand after the impact of a giant meteorite, which created a tsunami with 90-meter waves.
Traditional hypotheses suggest that the darkness created by the dust cloud resulting from the impact prevented photosynthesis and interrupted primary productivity in the oceans, causing consecutive extinctions along the trophic chain.
Laia Alegret ran a publication in PNAS in 2012 that showed that extinctions in the oceans were not related to the cessation of photosynthesis, but pointed to a rapid ocean acidification event, much faster than the current one, and resulting in ejection gases as the main cause of selective extinction in marine environments.
The hypothesis now being shown in the study that publishes this journal.
Analysis of marine microscopic fossils (foraminifera) found at the Geulhemmerberg mine in the Netherlands allowed the first measurement of seawater pH after the impact of the Late Cretaceous, showing that this is a key mechanism in the ecological collapse of the oceans
Geochemical analysis of carbon and boron in shells of foraminifera, which required the study of up to 7,000 microfossils per sample, indicate a decrease in water pH of 0.3 units and a large increase in atmospheric CO2 (700 parts per million), This is the first empirical measure on the mechanisms that triggered extinction.
Samples from several locations in the United States and ocean exploration of the Atlantic and Pacific were also analyzed.
The study also includes modeling global changes in ocean geochemistry and allows us to rule out that the impact has caused an increase in volcanic activity.
Show it the recovery of ocean chemistry and marine ecosystems is slowly re-establishing itself after global disturbancesDespite the fact that marine plankton and primary productivity evolved rapidly after extinction, a theory confirmed by another study was published, in which Alegret also collaborates with researchers at Yale University, Boulder Colorado, and MIT-MA in the journal Paleoceanography and Paleoclimatology.
The announcement in PNAS is an example that geologically rapid events such as meteorological impact or ocean acidification can have profound effects on long-term life and have implications for studies on current climate change.
Laia Alegret also participated in 2017 on an international expedition to a new continent, Zealand, which is almost submerged and shows only its highest mountains, the islands of New Zealand and New Caledonia for marine exploration.