Alarming levels of toxic mercury have been detected in the soil of ancient Mayan cities

A team of international researchers has recently reported high concentrations of mercury in the soil of seven sites in ancient Mesoamerica, the region that comprises modern-day Mexico and Central America. The mercury concentrations have been found between 0.016 ppm (parts per million) and 17.16 ppm at these sites.

You can imagine the level of mercury pollution there from the fact that any number above 0.05 ppm makes the soil unsafe for agriculture and more than one ppm makes food unhealthy. Mercury pollution infuses toxicity into the soil, water, food, and the entire food chain, and therefore, it could cause several health issues in humans ranging from skin rashes, liver infections, and kidney failure to blindness, mental health problems, and even paralysis.

According to the researchers, the rock composition of the Mayan sites indicates that mercury was not among the elements that naturally occurred at these places. They believe that the ancient Maya people actually imported the toxic element from somewhere else, but why did they do so? This is still a mystery.

Explaining this further, the first author of the study, Duncan Cook, told Frontiers, “Mercury pollution in the environment is usually found in contemporary urban areas and industrial landscapes. Discovering mercury buried deep in soils and sediments in ancient Maya cities is difficult to explain until we begin to consider the archeology of the region, which tells us that the Maya were using mercury for centuries.”

Moreover, the researchers also found a pigment called cinnabar (mercury sulfide or HgS) many and vessels containing liquid mercury at the Mayan sites.

Possible reasons for mercury pollution in Mayan cities

The time between 250 CE to 950 CE (1100 CE, according to some other sources) is called the classic Maya period, during which the cultural influence of the Maya civilization reached its peak. Even at present, Mayan culture, language, and traditions are followed by many people living in Guatemala. Moreover, some elements of the civilization, such as the Mayan calendar, still create a lot of excitement, buzz, and confusion in the media.

For instance, the doomsday predictions about December 21, 2012, were said to be as per the calculations of the Maya calendar. However, in reality, the Maya calendar never predicted the end of the world. Now the discovery of mercury-rich soil at the Mayan sites again raises a lot of questions.

The historical sites studied by the researchers actually represent the remains of a civilization that originally existed between 3000-4000 years ago. “We simply do not know enough yet about the mercury that is being detected at ancient Maya sites, how it got there, and what forms it takes today in the environment, 1000 or more years after the Maya,” Professor Cook told Cosmos Magazine.

The researchers reveal that although the impact of mercury on the physical and mental health of Mayan people is not known, traces of the element have been previously discovered in skeletons excavated from the sites in Mesoamerica. It is believed that cinnabar, the red color mercury pigment, also held special importance for the Maya people. They considered red as the color of death and spirituality and used to apply cinnabar on the dead bodies and graves.

Another reason for mercury concentration in the soil could be the use of cinnabar and mercury for painting houses, terraces, buildings, and ceramics. It is possible that over time the mercury from the paint made its way into the environment. This is similar to how volatile organic chemicals from paint in modern-day buildings get released in the form of gas and affect the air quality of a space.

Mercury levels could reveal unknown aspects of the Mayan society

The highest level of mercury concentration, i.e., 17.6 ppm, was found in Tikal, an iconic ancient Mayan site that has remains of some of the most glorious temples and structures built by the Maya people. The researchers highlight a painting of the Dark Sun, the last king of Tikal, as a hint of mercury poisoning in Mayans.

In the painting, Dark Sun looks as if he is suffering from the type of obesity that is generally caused due to mercury poisoning. However, these are all just many of the possibilities that the evidence from the Mayan sites suggests. More research is required to pinpoint the exact reasons that led to the introduction of so mercury in the soil of ancient Mayan cities.

They note that the mercury pollution in the soil at the Mayan sites is more than even what is found in some modern industrial settings. Therefore, archaeologists and scientists should be careful while they study and conduct experiments there. The researchers believe that the findings from the current and related future studies could also help us further understand the role of mercury in shaping the ancient Mayan societies and cultures of Mesoamerica.

The original review is published in the journal Frontiers in Environmental Science.