Tuesday, December 22, 2020

An Ancient Maya City Had a Surprisingly Effective Water Filtration System

   Water is important for basic human survival. But it can even be dangerous; contaminated water can spread deadly diseases that have the potential to eradicate whole communities. Safe, clean water offers humanity one among its best chances to thrive.

Several ancient civilizations, including the Greeks, Egyptians, and Romans, filtered their water. Sanskrit writings dating back to 2,000 BCE also mention water treatment methods. Now, archaeologists have discovered the Maya of South America did too – and their water filtration system was incredibly effective.

In a reservoir in what was once the main Maya city of Tikal, the ruins of which crumble during a rainforest in present-day Guatemala, archaeologists have found zeolite and quartz – minerals that aren't local to the realm, and which are both effective at helping remove contaminants like microbes, heavy metals, and nitrogen compounds from water.

So effective, in fact, that they're both utilized in water filtration systems today.

"What's interesting is that this system would still be effective today, and therefore the Maya discovered it quite 2,000 years ago," said anthropologist Kenneth Barnett Tankersley of the University of Cincinnati.

Zeolite, specifically, is interesting. it is a natural crystalline compound of silicon and aluminum, linked via shared oxygen atoms to make an open space lattice. it's excellent absorption and activity properties, which makes it very effective at filtering water.

But, although the traditional Greeks and Romans used it as a pozzolan – an ingredient for cement – in aquatic structures like bridges and aqueducts, archaeologists thought that zeolite hadn't been used for water filtration until around the beginning of the 20th century.

"The apparent zeolite filtration system at Tikal's Corriental reservoir is that the oldest known example of water purification within the occident," the authors wrote, "and the oldest known use of zeolite for decontaminating drink within the world."

The ability to own clean water was of deep importance to the Maya, and of great concern, particularly to Tikal. The city's only water source was 10 reservoirs. Given the massive population, and therefore the highly variable climate that went through periods of seasonal drought, their potable was at risk of contamination from both microbes and cinnabar, or mercury sulfide, a pigment the Maya used heavily.

It stands to reason that they'd some means of keeping the water clean. So Tankersley and his team visited to investigate. They studied three of the biggest reservoirs within the ancient city, likewise as a neighborhood sinkhole as a sway for mineral composition.

The discovery was made within the Corriental reservoir, a crucial source of drink for the residents of Tikal, and one of all the biggest water reservoirs in use by the Maya for over 1000 years. Mixed in among the sediment at the underside of the reservoir, the team found what they were looking for: zeolite and coarse quartz sand.

The zeolite was found only within the Corriental reservoir. there isn't any way it could have just happened to be there when the reservoir was dug.

In fact, the team believes that the mineral was quarried from a site some 30 kilometers (18 miles) northeast of Tikal. There, igneous rock forms an aquifer known to provide exceptionally clear water. University of Cincinnati geographer Nicholas Dunning was aware of the world after previously conducting fieldwork there.

"It was an exposed, weathered volcanic tuff of quartz grains and zeolite. it absolutely was bleeding water at a decent rate," Dunning said. "Workers refilled their water bottles with it. it had been locally famous for a way clean and sweet the water was."

The team compared the Corriental quartz and zeolite from material taken from the aquifer and located that the 2 were a really close match. They also used geological dating to see the age of the sediment and dated it to between 2,185 and 965 years ago.

It's impossible to understand exactly how the filtration system worked, but building the evidence, the team believes that it's a fairly good picture.

water filter(Tankersley, et al. Scientific Reports, 2020)

"The filtration system was likely held behind dry-laid stone walls with the zeolites and macrocrystalline sand-sized quartz crystals further constrained with woven petite (woven reed or palm fiber matting) or other perishable porous material positioned just upstream of, or within the reservoir ingresses, which were periodically ejected into the reservoir during flash floods caused by tropical cyclones," the researchers wrote in their paper.

And it seems to own worked. Mercury deposits, likely from cinnabar contamination, had previously been found in several other Tikal reservoirs. Not a trace of it can be detected in Corriental.

"The ancient Maya lived in an exceedingly tropical environment and had to be innovators. this can be an interesting innovation," Tankersley said.

"A lot of individuals observe Native Americans within the occident as not having the identical engineering or technological muscle of places like Greece, Rome, India, or China. But when it involves water management, the Maya were millennia ahead."

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