What caused residents to abandon the ancient settlement that made the area near Cahokia, Illinois, home to the biggest city in the Western world? At its peak approximately 1,000 years ago, the settlement was bigger than London. But by A.D. 1400, it was virtually deserted.
Cahokia’s collapse has long been a subject of speculation. For several decades, one of the most persistent theories has blamed self-inflicted ecological disaster. First suggested by researchers at Southern Illinois University-Edwardsville in 1993, the theory held that the Mississippians who inhabited the city cut down forests in the nearby uplands, leading to erosion and flooding.
But the evidence underlying the theory was negligible, said geoarchaeologist Caitlin Rankin. The researchers knew that the people living in the area used wood, and that “there was increasing use of upland trees, happening more towards the end of Cahokia’s occupation,” she explained on Tuesday’s St. Louis on the Air.
It’s a cool spring morning as I stare at the patchwork of colorful leaves and blossoms on the trees outside my home office. The thought of another Earth Day has me pondering all the research conducted at the University of Illinois Urbana-Champaign that has direct ecological implications. My colleagues and I have written about hundreds of these studies, and hundreds more are published every year.
Experts from the Illinois State Water Survey have been working since 2015 with the Metropolitan Water Reclamation District of Greater Chicago (MWRD), supporting MWRD in making informed watershed management decisions for its vast service area that includes 128 suburban communities in Cook County.
The first two phases of this long-term project have had a major impact on development throughout the region and helped define one of the most visible aspects of stormwater management: detention requirements.
Researchers at the Illinois Natural History Survey (INHS) have developed the new American Crayfish Atlas, the first website to provide nationwide coverage of crayfish distributions, showing where crayfish species have been found and the extent of their ranges.
When using the American Crayfish Atlas, viewers can select specific species to find their range across the U.S., select information for a particular state, and use zoomable maps to learn which crayfish species are in their area.
Prior to the atlas, those seeking information on crayfish distributions might have discovered that the information found online is either difficult to find or is state-specific, making it hard to realize species’ full ranges.
“There was an obvious need for readily available crayfish distribution data for the entire U.S., not only for professional biologists, but also for the public to see which species were found within 10 miles of where they live,” said INHS curator Chris Taylor, who envisioned and then co-developed the atlas with one of his graduate students.
The atlas contains more than 43,000 records, gleaned from the INHS crustacean collection and from over 50 sources, including museums and the research literature and various institutions and state agencies, whose information had not been cataloged or made visible online.
Taylor and graduate student Caitlin Bloomer have ensured that the website data have been quality controlled. In developing the site, they looked for possible misidentifications, outdated taxonomy, and other errors in the historical data, such as wrong numbers in geographic coordinates that would indicate the incorrect location or the wrong species name. This process continues as they add records.
“Crayfish taxonomy has been changing rapidly in the last decade or so, with several new species described in the last few years,” Bloomer said. “This means that you must look through every Excel file that comes in and make sure all the scientific names have been updated.”
The atlas is particularly valuable for researchers and state and federal management agencies involved in making crayfish conservation assessments, Taylor said. One of the primary criteria to evaluate the species of greatest conservation need is the total extent of their range.
With the atlas, groups and agencies can quickly and accurately determine the ranges for various crayfish species. The site will also assist researchers in their crayfish studies and provide information for anyone who would like to know which species of crayfish may be found in an area or which species they might have seen while outdoors.
“Hopefully, the atlas will help spark research interests and garner more interest in these charismatic little crustaceans,” Bloomer said.
ISTC is part of a national team to develop artificial intelligence technologies to sort non-recyclable plastics so they can be reused for fuels. The U.S. Department of Energy has awarded the team $2.5 million to complete the three-year project.
Plastics recycling in the U.S. typically requires manual sorting as workers pick out the useful kinds of plastic from conveyor belts and discard the non-recyclable types. This process is labor-intensive and expensive. In this new project, scientists are using high-tech sensors developed by UHV Technologies, Inc. and commercialized through its spin-off Sortera Alloys that will detect specific chemical-based “fingerprints” of each kind of plastic polymer, classifying them through a new system and sorting them into different bins.
“Sensor fusion and artificial intelligence algorithms used in the process will increase the speed and accuracy of plastic sorting, eventually making the technology more economical with a cost goal of less than $30 per ton,” said BK Sharma, co-principal investigator of the project.
Sensor fusion will generate a unique fingerprint for plastic pieces, while deep learning and artificial intelligence algorithms will create a novel classification system for the plastics.
Another challenge for the project is to reduce plastic contamination, a major reason why plastics end up in landfills. One of the project goals is to develop low-cost methods that decrease contamination to less than 5 percent. Improving the purity of plastic waste increases its potential and value for reuse.
A successful process that produces clean plastics, separated by type, could offer marketable products while diverting non-recyclable materials (plastics #3–#7) from landfills. Sharma’s primary role will be to use the catalytic pyrolysis process to determine if the plastics can be used to produce valuable products, primarily diesel or aviation fuels along with gasoline, naphtha, and waxes.
Besides ISTC, the team includes:
UHV Technologies, which has created sorting technologies for other products;
The Idaho National Laboratory, to complete chemical composition analysis and screening techniques; and
The Solid Waste Authority of Palm Beach County, which will help to integrate the proposed technology into the existing recycling industry.
“At the end of the project, if we can come up with a process that can convert mixed plastic into a low-cost feedstock to produce different types of fuels and other products, that will be a big success,” Sharma said.
Plastic products permeate our environment and over time they break down. The microscopic size of particles, how long they last, and what is associated with them raise health concerns.
Although the health effects are still largely uncertain, recent research at the Illinois Sustainability Technology Center (ISTC) has provided some insight into what happens to plastics once they’re used and thrown away.
Microplastics are everywhere: in what we eat, drink, and breathe, according to ISTC senior chemist John Scott. They’re found in surface water, sediments and soils, air and dust, wildlife, and everywhere else scientists look.
“Plastics don’t ever go away, they just break down to smaller and smaller sizes,” Scott said. “They’re always out there. If I analyze something that doesn’t have microplastics in it, I think there’s something wrong.”
Plastics have been mass-produced since the 1950s, with an estimated 8.3 billion metric tons produced globally. Nearly 80 percent of plastic waste ends up in landfills and in the environment. The COVID-19 pandemic has exacerbated the plastic waste problem with more shipping and packaging and the worldwide use of single-use products, such as gloves, gowns, and booties.
Since plastics have been engineered to last, the breakdown rates are incredibly long. Nylon fishing line lasts some 600 years, plastic bottles last 400 years, and plastic straws last 200 years.
“A child’s diaper can be around for 400 to 500 years—five to six times the child’s lifespan,” Scott said. “Even if we stopped producing plastics now, because of these legacy products, we would still have a plastic waste problem for many decades.”
What they absorb
Plastics act as sponges, absorbing all kinds of contaminants in the environment. In 2020, Scott and collaborators at the Annis Water Resources Institute submerged samples of different types of plastic for three months in Muskegon Lake in Michigan.
Findings showed that many pollutants such as polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and even pesticides concentrate on these materials at hundreds of times the background levels.
The group also found a group of chemicals, per- and polyfluoroalkyl substances (PFAS), can stick to microplastics submerged in lake water. PFASs are human-made chemicals used in products such as non-stick cookware, cleaning supplies, and food packaging. Their stability and water and oil resistance are useful for various products, but the PFASs don’t break down readily in the environment or in humans, causing potential adverse health effects.
Scott’s team also tested PFAS adsorption on plastic in the laboratory, without the presence of organic matter such as biofilms. In the laboratory, the amount of PFASs that was absorbed into the microplastics was small (about 25%), yet the lake-exposed samples showed 600 times more PFASs were attached to the microplastics compared with those in the laboratory tests.
“We found only small concentrations of PFASs, but what was interesting was the discovery that they don’t stick to the plastic,” Scott said. “We believe that they stick to a biofilm of organic material that develops over time on the plastic from the lake environment.”
To understand microplastics and make accurate comparisons of plastic size and concentrations, researchers need to use a standardized method of detection limits. The National Oceanic and Atmospheric Administration (NOAA) developed a method in 2015, which was designed to measure large plastic debris in surface water and on beaches.
The smallest size detected through this process is 300 micrometers, which does not account for microplastics that are small enough to cross biological membranes.
“We needed to push the detection limits to measure smaller microplastics,” Scott said. “If we use the NOAA method, we’ll underestimate the amount of microplastics in a sample.
In 2020, Scott and Lee Green, ISTC chemist, developed a way to count microplastics down to the size of 20 micrometers, sizes that would have been missed by the NOAA standard.
Another challenge was to find a standardized way to report findings. Estimating the number of plastic particles per liter wasn’t accurate because the particles can further break down during the estimation process. Instead, Scott and his team applied a detailed analysis of particle dimensions to estimate its mass.
What happens to them from the landfill to the treatment plant
Microplastics might be everywhere, but the hotspots are landfills. Plastic breaks down in landfills and becomes more mobile. Leachate, or water and waste from the landfill, is piped to wastewater treatment plants (WWTP), which are not designed to handle microplastics.
The sludge produced by WWTPs is commonly used on crop fields since the biosolids are high in nutrients. Once applied, the sludge material—and microplastics—is taken up by plants and runs into surface water and groundwater.
Scott plans a pilot study to examine the feasibility of treating wastewater to remove microplastics that come into plants before sludge is pumped back out into the environment.
Ideally, though, keeping plastics out of the landfills by reducing the amount produced, using fewer single-use plastic products, and better plastic recycling would be the way to go, Scott said.
The Metropolitan Water Reclamation District of Greater Chicago has published a story about their water quality projects in Fulton County. ISTC researcher Wei Zheng is one of the researchers involved in this collaborative effort.
In addition to deploying new nutrient recovery technology, the MWRD voluntarily established a program at its Fulton County site to foster collaboration with the agricultural sector to develop and expedite nutrient reduction practices in non-point source areas.
The 13,500-acre property, located in Fulton County between Canton and Cuba, Illinois, was originally purchased in 1970 to restore strip-mined land and approximately 4,000 acres were converted to productive farmland. Years later it became the ideal site to use some of the farm fields to develop and test best management practices to reduce non-point source nutrients.
Since 2015, research and demonstration projects have been established at the site in collaboration with many partners such as the University of Illinois at Urbana-Champaign (UIUC) Crop Science Department, UIUC Department of Agricultural and Biological Engineering, Illinois Sustainable Technology Center, Illinois Central College, Ecosystem Exchange, IFB, and Fulton County Farm Bureau. The projects established include inter-seeded cover cropping, riparian grass buffer, denitrifying bioreactors, runoff irrigation, subirrigation, drainage water managements, designer biochar, and watershed-scale nutrient reduction demonstration.