(CN) — Finding a natural and sustainable system for water — the most valuable resource for life on Earth — in certain regions is becoming more difficult every day. A new study published Monday suggests looking to ancient Maya reservoirs and how they naturally purified water while supporting agriculture for over 1,000 years.
The perspective, published Monday in the Proceedings of the National Academy of Sciences, comes from University of Illinois Urbana-Champaign anthropology professor Lisa Lucero, an expert on Classic Maya civilization along with ritual, political power, climate change and sustainability.
Lucera suggests that between 250 and 900, Maya civilization in the southern lowlands of Central America overcame water scarcity amid annual, five-month dry seasons and climate instability with urban reservoirs akin to constructed wetlands.
Such reservoirs, she explains, provided clean water for up to tens of thousands of people, and they did so despite the danger of still-water systems becoming stagnant and undrinkable due to algae, and their tendency to provide a favorable breeding environment for disease-spreading insects like mosquitos.
Lucero posits that such systems allowed the Maya to cultivate fertile lands — perhaps lending to the civilization’s prestigious agricultural history — by supporting aquatic species that prey on water-degrading pathogens and bacteria.
“Most major southern lowland Maya cities emerged in areas that lacked surface water but had great agricultural soils,” Lucero said in a statement. “They compensated by constructing reservoir systems that started small and grew in size and complexity.”
Similar to modern water management, the Maya directed, stored and transported water with canals, dams, sluices and berms. To filter water, however, the Maya used several natural resources, starting with quartz sand and zeolite sand — both of which were only available in distant areas.
Sediment cores from reservoirs in cities like Tikal or modern-day northern Guatemala back up the Maya use of zeolite sand, a volcanic mineral known to filter water impurities and dangerous microbes. Within the same region, the massive reservoirs — capable of holding 237,754,847 gallons of water, or about 396 Olympic-sized pools — are estimated to have met the water needs of up to 80,000 residents and their crops from the seventh to ninth centuries.
Lucero explains how the reservoirs’ ability to sustain the region during droughts earned Maya royalty higher status.
“Clean water and political power were inextricably linked as demonstrated by the fact that the largest reservoirs were built near palaces and temples,” Lucero wrote. “Royals thus were busiest and the most powerful in the dry season when everyone needed clean drinking water.”
In addition to providing clean water, kings were expected to perform rain and water ceremonies to appease ancestors and gods like Chahk, the rain god.
With any reservoir, there’s always the challenge of preventing standing water from becoming stagnant and undrinkable. To address this, Lucera suggests that the Maya utilized native aquatic plants like cattails, reeds and sedges — macrophytic plants that filter water and reduce murkiness while absorbing nitrogen and phosphorous.
Lucero also points out how these reservoirs likely supported beneficial biota found in Central American wetlands today, including species of fish, eels, turtles, crustaceans, mollusks and snails.
“Fish feces and other bottom debris, which the Maya would have had to dredge every several years, provided a potential source of fertilizer,” Lucera wrote, later adding that, since macrophytic plants live year-round, the Maya likely maintained reservoirs year-round and extracted debris and plants to fertilize urban fields and gardens.
Among the most valuable plants was the water lily, Lucera wrote, as it indicated clean water while symbolizing “Classic Maya kingship.” For instance, she noted how kings and water lilies were depicted together on monumental architecture, stelae, murals and portable objects. The kings, she wrote, also wore water lily headdresses, while inscriptions at the time make note of the “Nab Winik Makna" or "Water Lilly Lords” and “Ah Nah," or "Water Lily People.”
As for the flower’s ability to detect clean water, Lucero explains how water lilies are intolerant of acidic conditions from high concentrations of calcium, iron and manganese.
“Further, since water lily roots attach to the bottom sediment, if it contains too much decomposing organic matter, released gases such as methane, ethylene and phenols can be toxic to them,” Lucero said, adding that the Maya would have had to line the reservoirs with materials like clay to stabilize pH levels.
The water lilies, along with other plants, provided water reservoirs with cool shade while inhibiting algae growth.
“While sunlight is important to remove bacteria and viral pathogens, in this case, plants and other aquatic biota fill this role," Lucero added.
Maya reservoirs only failed during the most severe droughts between 800 and 900, Lucero said. In times like today, where extreme climate events are becoming more common globally, the author believes we will need to adopt similar approaches to the Maya, plants and all.
Such water systems, Lucera says, provide advantages over conventional wastewater treatment systems, including low costs, high energy-saving treatment technology and clean water that supports aquatic animals and agriculture.
The next step, the author writes, “is to combine our respective expertise and implement the lessons embodied in ancient Maya reservoirs in conjunction with what is currently known about constructed wetlands.”
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