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Coral species Cladocora caespitosa. Credit: Diego K. Kersting
Pollutants from fossil fuel combustion have been found embedded in coral for the first time, giving scientists a potential new tool to trace the history of pollution, UCL research says. This was discovered in a new study by researchers.
the study, published in diary Total environmental scienceidentified carbon particles released by the combustion of fossil fuels embedded in corals in Ila Grossa Bay, off the coast of the Colombretes Islands in the Mediterranean Sea. Finding that this type of pollution, known as fly ash or spherical carbonaceous particles (SCP), contaminates natural sediments is an indicator of the presence of human impact on the environment, and It is considered a historical marker of the beginning of the considered era.
Corals are natural archives commonly used for paleoclimate research because their growth rates are measurable. Like tree rings, their long lifespan and slow, regular growth allow scientists to obtain annual, monthly, and even weekly environmental data going back several years.
Until now, it has been primarily used to measure past climate conditions such as water temperature and chemicals, but this is the first time that pollutant particles other than microplastics have been recovered from corals.
Lead author Dr Lucy Roberts (UCL Geography) said: ‘The discovery of these pollutants embedded in coral skeletons has been going on for decades and underlines just how widespread human impact is on the environment. “This is the first time we have investigated this.” These types of pollutants can be observed in corals, and their appearance in these sediments is consistent with historical fossil fuel burning rates in this region. ”
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Coral species Cladocora caespitosa. Credit: Diego K. Kersting
Corals are small invertebrates that tend to live in vast colonies, ingesting and incorporating SCP pollutants from surrounding waters as they grow their calcium carbonate skeletons.
Researchers from the Institute of Torre de la Salle (IATS-CSIC) collected coral samples from several locations along a coral reef off the coast of Castello, Spain. The coral species Cladocora caespitosa has been studied and monitored there for 20 years, and the site is considered a monitoring site for global change.
The coral is located within a protected marine reserve approximately 60 kilometers from the coast, so the potential for local pollution is minimized. This species is the only Mediterranean coral with the ability to form large reefs and is known to grow on average about 0.3 centimeters per year.
Once in the UCL lab, the corals were dissolved with acid, leaving behind tiny particles of pollutants embedded in their skeletons. The team first counted all the SCPs within the ruins under a microscope. He then viewed the samples under an electron microscope and analyzed them with X-rays to look for chemical traces of his SCP contamination that would indicate a coal or oil power plant.
The research team found that SCP contamination of corals increased significantly from around 1969 to 1992. This corresponded to a period when Europe was rapidly industrializing and domestic coal consumption increased dramatically.
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Ila Grossa Bay, a large bay on a large island in the Colombretes Islands off the coast of Spain. Credit: Diego K. Kersting
These results are consistent with other measurements of SCP pollution taken in mountain lakes in Spain, and indicate that corals may act as natural archives for measuring changes in pollution levels over the years. This supports this idea.
These discoveries are a result of geological phenomena that scientists use to describe the most recent era in Earth’s history, when human activity became the dominant influence on Earth’s climate and environment. It was discovered while searching for a tool to mark the beginning of the Anthropocene, a unit of time. .
Many scientists advocate using the presence of SCPs as an indicator of the beginning of the Anthropocene, and the discovery of SCPs in coral skeletons supports this argument. It has already been identified in lake and ocean sediments, ice cores, and peat layers.
Dr Roberts said: ‘These pollutants are serving as an indelible marker marking the beginning of the Anthropocene, as it becomes clear that humans have modified the natural environment to unprecedented levels. “It will be valuable to researchers seeking a deeper understanding of history.” The impact on the natural world is a stark reminder of how far-reaching human influence is on the environment. ”
The research was led by UCL and carried out in collaboration with Spain’s Torre de la Sal Aquarium and the University of Leicester.
For more information:
LR Roberts et al. first record the presence of anthropogenic fly ash particles in coral skeletons. Total environmental science (2024). DOI: 10.1016/j.scitotenv.2024.170665