Earth Is Facing Most Severe Extinction Crisis in 65 Million Years
Earth's living community is now suffering the most severe biodiversity crisis in 65 million years, since a meteorite struck near modern Chicxulub, Mexico, injecting dust and sulfuric acid into the atmosphere and devastating 76 percent of all living species, including the dinosaurs.
Ecologists now ask whether or not Earth has entered another "major" extinction event, if extinctions are as important as general diversity collapse and which emergency actions we might take to reverse the disturbing trends.
Biodiversity decline is now higher than any time since the Chicxulub asteroid impact. Photo credit: Todd Warshaw / Greenpeace
In 1972, at the first UN environmental conference in Stockholm, Stanford biologist Paul Ehrlich, linked the collapse of "organic diversity" to human population and industrial growth. In 1981, he published Extinction, explaining the causes and consequences of the biodiversity crisis and providing response priorities, starting with stabilizing human population and growth.
This summer, Ehrlich, Gerardo Ceballos (University of Mexico) and their colleagues, published "Accelerated modern human–induced species losses" in Science Advances. "The study shows," Ehrlich explains, "that we are now entering the sixth great mass extinction event." To demonstrate that Earth is experiencing a "mass extinction event" depends on showing that current extinction rates far exceed normal "background" extinction rates. To be absolutely certain, Ehrlich and Ceballos used the most conservative estimates of current extinctions, which they found to be about 10-to-100-times faster than the background rate.
There are three points worth keeping in mind:
- most extinction rate estimates from biologists range from 100 to 1000 times faster than background.
- this modern extinction rate is accelerating with each passing year.
- the general diversity collapse, even among species that don't go extinct, remains equally serious for humanity.
Biodiversity decline is now higher than any time since the Chicxulub asteroid impact. This time, however, humans are the asteroid.
I've used the term "ninth extinction" because the so-called "five major extinctions" occurred in the last 450 million years, but three earlier extinctions are significant and teach us something important about ecology and our potential role in emergency response.
Ancient toxic waste
Some 3.5 billion years ago, as Earth cooled enough to sustain complex molecules, anaerobic bacteria formed, single-cell marine organisms living without oxygen and extracting energy from sulphur. Within a few hundred million years, some bacteria and algae learned to collect solar energy through photosynthesis, releasing oxygen into the sea. About 2.5 billion years ago, free oxygen became life's first global ecological crisis.
Oxygen is toxic to anaerobic bacteria. Some species perished at only 0.5 percent oxygen, while others survived up to 8 percent oxygen. Oxygen eventually saturated the oceans, leaked into the atmosphere and oxidized methane, triggering a global cooling, the "Huronian glaciation," which led to more extinctions.
The evolutionary success of photosynthetic bacteria and algae triggered impacts similar to our own: crowded habitats, toxic waste, atmospheric disruption, temperature change and biodiversity collapse. Sound familiar? The die-off continued until certain organisms evolved to metabolize oxygen and the ecosystem regained a new dynamic equilibrium. We could help our situation by encouraging organisms that metabolize carbon dioxide, namely plants, but we are reducing forest cover, adding to the crisis.
In Newfoundland, Canada, in 1868, Scottish geologist Alexander Murray, found unusual disc-shaped organisms, Aspidella terranovica, in rock formations that pre-dated known animal forms, so most paleontologists doubted they represented a new fauna. However, in 1933, more specimens appeared in Namibia and in 1946, jellyfish fossils from this era appeared in the Ediacara Hills of Australia. These organisms, now known as the "Ediacaran" fauna, had no shells or skeletons, so they left only rare fossil impressions.
Oxygen metabolism allowed organisms to use nitrogen and to transform more energy, allowing complex morphologies, cell nuclei and symbiotic relationships within cells and among organisms. For another billion years, cells diversified, learned how to replicate by dividing (mitosis), then by sex (meiosis) and how to cooperate to form multi-cellular plants and animals. By 650 million years ago, Ediacaran life had diversified into unipolar, bipolar and radial organisms, including worms, sponges and jellies.
This abundance collapsed about 542 million years ago, possibly associated with meteorite impacts and an oxygen drop. More than 50 percent of the species probably perished. Typically, however, this extinction opened ecological niches for the explosion of life forms that followed.
Life tries again
Organisms that survived the Ediacaran collapse diversified during the so-called "Cambrian explosion." Life had already evolved for three billion years, before the appearance of crustaceans, arthropods (insects), Echinoderms (starfish, urchins), molluscs and our own ancestors, the chordates. Earth had been warming, but burgeoning marine plant life captured carbon-dioxide from the atmosphere, causing a cold period and around 488 million years ago, some 40 percent of the Cambrian species disappeared.
Typically, we measure extinction events by the numbers of species or families that disappear, but in this case, some phyla—fundamental life forms—perished. The extent of Cambrian phyla diversity remains controversial among biologists. In 1989, Harvard paleontologist Stephen Jay Gould published A Wonderful Life, in which he proposed numerous extinct Cambrian Phyla.
Some unusual Cambrian creatures may be earlier stages of existing forms, but some phyla likely perished at the end of the Cambrian. These early animals remain difficult to classify, so modern taxonomy incorporates "stem groups" of partially formed phyla. Cambrian oddities such as Odontogriphus and Nectocaris—may be stem groups related to molluscs. Or maybe not. Nectocaris possesses an arthropod-type head on a body with fins, similar to the chordates. Aysheaia, a lobopod with walking appendages, may represent a stem group related to later arthropods. The stunning Cambrian Pikaia—with a rudimentary backbone, no clear gills, unique muscle styles and tentacles—could be an extinct phyla. Vetulicolia—a worm-like animal with insect features, vertebrate, no eyes and no legs or feelers—probably represents an extinct phyla.
Losing phyla may be a unique quality of this Cambrian extinction event. After three billion years and three major extinctions, life's fundamental forms settled into the roughly 90 phyla that endure to this day: 35 animal forms (many rare; Placozoa, for example consists of a single known species), 12 plant forms, 14 fungi and 29 bacteria, plus the more obscure microorganisms archaea and protista. Most of the species we discuss and protect—birds, fish, reptiles, mammals—arise from a single phyla, the chordates and occasionally insects, molluscs, worms and corals.
Click to view full-sized. Photo credit: Greenpeace
After the Cambrian collapse, species diversity did not significantly increase for 300 million years, as life filled the marine habitats and moved onto land. Dozens of serious diversity collapses occurred during this time. The "Lau Event," 420 million years ago (mya), caused by climate change, erased about 30 percent of the species. During the Carboniferous period, 305 mya, a booming rainforest captured carbon and set off a global cooling that triggered widespread extinctions.
The approximately 90 essential life forms, however, endured through these disruptions and through the modern "5 major extinctions:"
Ordovician: 440 million years ago (mya), 85 percent species, 25 percent families perish, all marine, possibly caused by a solar gamma ray burst that depleted ozone protection.
Devonian: 370 mya, 83 percent species, 19 percent families perish, all marine, likely caused by volcanos, meteorite or both.
Permian, the big one: 250 mya, 95 percent marine, 70 percent terrestrial species and 54 percent of the families perished, the largest known diversity collapse in Earth history, likely caused by volcanic eruptions that increased carbon-dioxide and warming.
Triassic, 210 mya, 80 percent marine, 35 percent terrestrial species, 23 percent families gone, likely caused by volcanic eruptions releasing carbon and sulphur dioxide, triggering more warming.
Cretaceous: Demise of the dinosaurs, 65 mya, 76 percent species loss, caused by the meteorite that struck near Chicxulub, Mexico.
The three ancient extinctions and five modern extinctions, bring us to the current diversity collapse, primarily caused by human expansion on Earth.
The Human Asteroid
Massive biodiversity reductions, even among animals that do not go extinct, destabilize an ecosystem. "There are examples of species all over the world," Paul Ehrlich explains, "that are essentially the walking dead." Certain plant and animal populations may become so small that they may not recover, or may lose symbiotic function in the ecosystem. Depleted pollinators or prey species can create cascading extinctions. According to World Wildlife Fund and the Zoological Society of London, Earth has lost half its wild animals in 40 years, through habitat loss, hunting, poaching, climate change, toxins and invasive species.
At Seahorse Key, formerly the largest bird colony on the Gulf Coast of Florida, thousands of herons, spoonbills, egrets and pelicans have abandoned the rookery, possibly in response to low-flying drug-enforcement aircraft. Bird species are declining in most habitats and more than 12 percent are threatened with extinction.
Amphibians suffer the highest extinction and depletion rates (McCallum, 2007). More than a quarter of all reptiles are at risk and 37 percent of freshwater fish (IUCN). More than 100 mammals have gone extinct in the era of European expansion and today, 22 of the 30 surviving large mammal carnivores are listed as "endangered" by the World Conservation Union, including African wild dogs, Black rhinos and the few surviving Mountain gorillas.
Today, 22 of the 30 surviving large mammal carnivores are listed as "endangered" by the World Conservation Union. Photo credit: Andrew Wright / www.cold-coast.com
About 1.7 million species have been classified by taxonomists and about 15,000 are added to this list each year. Biologists estimate that there may be 30-40 million species, plus perhaps billions of microbe species.
The conservative Ehrlich/Ceballos study confirmed that the extinction rate was up to 100-times the background rate, but most studies estimate much higher: A Brown University study in 2014 estimates that current extinctions are 1000-times faster than background. A study from S.L. Pimm and colleagues in Science journal estimates 1000-times higher. A study by Pimm and Jurriaan de Vos, published in Conservation Biology suggests current extinction rates are 1,000 times higher than background and heading toward 10,000 times higher.
Thus, by any reasonable measure Earth is undergoing a major biodiversity collapse, almost entirely caused by human activity. "If it is allowed to continue," Gerardo Ceballos warns, "life would take many millions of years to recover and our species itself would likely disappear early on."
Ehrlich, identified the fundamental cause more than forty years ago: Human sprawl. Ehrlich and colleagues calculated in 1986 that humanity was using about 40 percent of Earth's Net Primary Productivity. Today, with 7.1 billion humans, we are using more than half of Earth's productivity and the other 30-million species survive on the left-over habitats. If human population reaches 11 billion, we will likely require about 80 percent, although such a scenario may not be biophysically possible.
Land and air vertebrate biomass on Earth, "Fossil Fuels and Human Destiny." Photo credit: Ron Patterson
The history of life on Earth teaches us that successful life forms—bacteria, forests, or tool-wielding primates—typically grow beyond the capacity of their habitats, change those habitats and set the stage for their own decline. Are we smarter than the bacteria? Will humanity find ways to slow down, limit our own growth and preserve wild nature? Our track record is not promising. Our desires, economic and religious doctrines and polluting technologies all work against the necessary changes. We need a large-scale ecological renaissance in human affairs, a shift in awareness that will allow human enterprise to accept limits on its own expansion.
Rex Weyler is an author, journalist and co-founder of Greenpeace International.
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By Frank La Sorte and Kyle Horton
Millions of birds travel between their breeding and wintering grounds during spring and autumn migration, creating one of the greatest spectacles of the natural world. These journeys often span incredible distances. For example, the Blackpoll warbler, which weighs less than half an ounce, may travel up to 1,500 miles between its nesting grounds in Canada and its wintering grounds in the Caribbean and South America.
Blackpoll warbler. PJTurgeon / Wikipedia<p>We used this information to determine how the number of migratory bird species varies based on each city's level of <a href="https://www.britannica.com/science/light-pollution" target="_blank" rel="noopener noreferrer">light pollution</a> – brightening of the night sky caused by artificial light sources, such as buildings and streetlights. We also explored how species numbers vary based on the quantity of tree canopy cover and impervious surface, such as concrete and asphalt, within each city. Our findings show that cities can help migrating birds by planting more trees and reducing light pollution, especially during spring and autumn migration.</p>
Declining Bird Populations<p>Urban areas contain numerous dangers for migratory birds. The biggest threat is the risk of <a href="https://doi.org/10.1650/CONDOR-13-090.1" target="_blank">colliding with buildings or communication towers</a>. Many migratory bird populations have <a href="http://dx.doi.org/10.1126/science.aaw1313" target="_blank">declined over the past 50 years</a>, and it is possible that light pollution from cities is contributing to these losses.</p><p>Scientists widely agree that light pollution can <a href="https://doi.org/10.1073/pnas.1708574114" target="_blank">severely disorient migratory birds</a> and make it hard for them to navigate. Studies have shown that birds will cluster around brightly lit structures, much like insects flying around a porch light at night. Cities are the <a href="https://doi.org/10.1002/fee.2029" target="_blank" rel="noopener noreferrer">primary source of light pollution for migratory birds</a>, and these species tend to be more abundant within cities <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.13792" target="_blank" rel="noopener noreferrer">during migration</a>, especially in <a href="https://doi.org/10.1016/j.landurbplan.2020.103892" target="_blank" rel="noopener noreferrer">city parks</a>.</p>
Composite image of the continental U.S. at night from satellite photos. NASA Earth Observatory images by Joshua Stevens, using Suomi NPP VIIRS data from Miguel Román, NASA's Goddard Space Flight Center
The Power of Citizen Science<p>It's not easy to observe and document bird migration, especially for species that migrate at night. The main challenge is that many of these species are very small, which limits scientists' ability to use electronic tracking devices.</p><p>With the growth of the internet and other information technologies, new data resources are becoming available that are making it possible to overcome some of these challenges. <a href="https://doi.org/10.1038/d41586-018-07106-5" target="_blank">Citizen science initiatives</a> in which volunteers use online portals to enter their observations of the natural world have become an important resource for researchers.</p><p>One such initiative, <a href="https://ebird.org/home" target="_blank" rel="noopener noreferrer">eBird</a>, allows bird-watchers around the globe to share their observations from any location and time. This has produced one of the <a href="https://doi.org/10.1111/ecog.04632" target="_blank" rel="noopener noreferrer">largest ecological citizen-science databases in the world</a>. To date, eBird contains over 922 million bird observations compiled by over 617,000 participants.</p>
Light Pollution Both Attracts and Repels Migratory Birds<p>Migratory bird species have evolved to use certain migration routes and types of habitat, such as forests, grasslands or marshes. While humans may enjoy seeing migratory birds appear in urban areas, it's generally not good for bird populations. In addition to the many hazards that exist in urban areas, cities typically lack the food resources and cover that birds need during migration or when raising their young. As scientists, we're concerned when we see evidence that migratory birds are being drawn away from their traditional migration routes and natural habitats.</p><p>Through our analysis of eBird data, we found that cities contained the greatest numbers of migratory bird species during spring and autumn migration. Higher levels of light pollution were associated with more species during migration – evidence that light pollution attracts migratory birds to cities across the U.S. This is cause for concern, as it shows that the influence of light pollution on migratory behavior is strong enough to increase the number of species that would normally be found in urban areas.</p><p>In contrast, we found that higher levels of light pollution were associated with fewer migratory bird species during the summer and winter. This is likely due to the scarcity of suitable habitat in cities, such as large forest patches, in combination with the adverse affects of light pollution on bird behavior and health. In addition, during these seasons, migratory birds are active only during the day and their populations are largely stationary, creating few opportunities for light pollution to attract them to urban areas.</p>
Trees and Pavement<p>We found that tree canopy cover was associated with more migratory bird species during spring migration and the summer. Trees provide important habitat for migratory birds during migration and the breeding season, so the presence of trees can have a strong effect on the number of migratory bird species that occur in cities.</p><p>Finally, we found that higher levels of impervious surface were associated with more migratory bird species during the winter. This result is somewhat surprising. It could be a product of the <a href="https://www.epa.gov/heatislands" target="_blank">urban heat island effect</a> – the fact that structures and paved surfaces in cities absorb and reemit more of the sun's heat than natural surfaces. Replacing vegetation with buildings, roads and parking lots can therefore make cities significantly warmer than surrounding lands. This effect could reduce cold stress on birds and increase food resources, such as insect populations, during the winter.</p><p>Our research adds to our understanding of how conditions in cities can both help and hurt migratory bird populations. We hope that our findings will inform urban planning initiatives and strategies to reduce the harmful effects of cities on migratory birds through such measures as <a href="https://www.arborday.org/programs/treecityusa/index.cfm" target="_blank" rel="noopener noreferrer">planting more trees</a> and initiating <a href="https://aeroecolab.com/uslights" target="_blank" rel="noopener noreferrer">lights-out programs</a>. Efforts to make it easier for migratory birds to complete their incredible journeys will help maintain their populations into the future.</p><p><em><span style="background-color: initial;"><a href="https://theconversation.com/profiles/frank-la-sorte-1191494" target="_blank">Frank La Sorte</a> is a r</span>esearch associate at the </em><em>Cornell Lab of Ornithology, Cornell University. <a href="https://theconversation.com/profiles/kyle-horton-1191498" target="_blank">Kyle Horton</a> is an assistant professor of Fish, Wildlife, and Conservation Biology at the Colorado State University.</em></p><p><em></em><em>Disclosure statement: Frank La Sorte receives funding from The Wolf Creek Charitable Foundation and the National Science Foundation (DBI-1939187). K</em><em>yle Horton does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</em></p><p><em>Reposted with permission from <a href="https://theconversation.com/cities-can-help-migrating-birds-on-their-way-by-planting-more-trees-and-turning-lights-off-at-night-152573" target="_blank">The Conversation</a>. </em></p>
EcoWatch Daily Newsletter
By Lynne Peeples
Editor's note: This story is part of a nine-month investigation of drinking water contamination across the U.S. The series is supported by funding from the Park Foundation and Water Foundation. Read the launch story, "Thirsting for Solutions," here.
In late September 2020, officials in Wrangell, Alaska, warned residents who were elderly, pregnant or had health problems to avoid drinking the city's tap water — unless they could filter it on their own.
Unintended Consequences<p>Chemists first discovered disinfection by-products in treated drinking water in the 1970s. The trihalomethanes they found, they determined, had resulted from the reaction of chlorine with natural organic matter. Since then, scientists have identified more than 700 additional disinfection by-products. "And those only represent a portion. We still don't know half of them," says Richardson, whose lab has identified hundreds of disinfection by-products. </p>
What’s Regulated and What’s Not?<p>The U.S. Environmental Protection Agency (EPA) currently regulates 11 disinfection by-products — including a handful of trihalomethanes (THM) and haloacetic acids (HAA). While these represent only a small fraction of all disinfection by-products, EPA aims to use their presence to indicate the presence of other disinfection by-products. "The general idea is if you control THMs and HAAs, you implicitly or by default control everything else as well," says Korshin.</p><p>EPA also requires drinking water facilities to use techniques to reduce the concentration of organic materials before applying disinfectants, and regulates the quantity of disinfectants that systems use. These rules ultimately can help control levels of disinfection by-products in drinking water.</p>
Click the image for an interactive version of this chart on the Environmental Working Group website.<p>Still, some scientists and advocates argue that current regulations do not go far enough to protect the public. Many question whether the government is regulating the right disinfection by-products, and if water systems are doing enough to reduce disinfection by-products. EPA is now seeking public input as it considers potential revisions to regulations, including the possibility of regulating additional by-products. The agency held a <a href="https://www.epa.gov/dwsixyearreview/potential-revisions-microbial-and-disinfection-byproducts-rules" target="_blank">two-day public meeting</a> in October 2020 and plans to hold additional public meetings throughout 2021.</p><p>When EPA set regulations on disinfection by-products between the 1970s and early 2000s, the agency, as well as the scientific community, was primarily focused on by-products of reactions between organics and chlorine — historically the most common drinking water disinfectant. But the science has become increasingly clear that these chlorinated chemicals represent a fraction of the by-product problem.</p><p>For example, bromide or iodide can get caught up in the reaction, too. This is common where seawater penetrates a drinking water source. By itself, bromide is innocuous, says Korshin. "But it is extremely [reactive] with organics," he says. "As bromide levels increase with normal treatment, then concentrations of brominated disinfection by-products will increase quite rapidly."</p><p><a href="https://pubmed.ncbi.nlm.nih.gov/15487777/" target="_blank">Emerging</a> <a href="https://pubs.acs.org/doi/10.1021/acs.est.7b05440" target="_blank" rel="noopener noreferrer">data</a> indicate that brominated and iodinated by-products are potentially more harmful than the regulated by-products.</p><p>Almost half of the U.S. population lives within 50 miles of either the Atlantic or Pacific coasts, where saltwater intrusion can be a problem for drinking water supplies. "In the U.S., the rule of thumb is the closer to the sea, the more bromide you have," says Korshin, noting there are also places where bromide naturally leaches out from the soil. Still, some coastal areas tend to be spared. For example, the city of Seattle's water comes from the mountains, never making contact with seawater and tending to pick up minimal organic matter.</p><p>Hazardous disinfection by-products can also be an issue with desalination for drinking water. "As <a href="https://ensia.com/features/can-saltwater-quench-our-growing-thirst/" target="_blank" rel="noopener noreferrer">desalination</a> practices become more economical, then the issue of controlling bromide becomes quite important," adds Korshin.</p>
Other Hot Spots<p>Coastal areas represent just one type of hot spot for disinfection by-products. Agricultural regions tend to send organic matter — such as fertilizer and animal waste — into waterways. Areas with warmer climates generally have higher levels of natural organic matter. And nearly any urban area can be prone to stormwater runoff or combined sewer overflows, which can contain rainwater as well as untreated human waste, industrial wastewater, hazardous materials and organic debris. These events are especially common along the East Coast, notes Sydney Evans, a science analyst with the nonprofit Environmental Working Group (EWG, a collaborator on <a href="https://ensia.com/ensia-collections/troubled-waters/" target="_blank">this reporting project</a>).</p><p>The only drinking water sources that might be altogether free of disinfection by-products, suggests Richardson, are private wells that are not treated with disinfectants. She used to drink water from her own well. "It was always cold, coming from great depth through clay and granite," she says. "It was fabulous."</p><p>Today, Richardson gets her water from a city system that uses chloramine.</p>
Toxic Treadmill<p>Most community water systems in the U.S. use chlorine for disinfection in their treatment plant. Because disinfectants are needed to prevent bacteria growth as the water travels to the homes at the ends of the distribution lines, sometimes a second round of disinfection is also added in the pipes.</p><p>Here, systems usually opt for either chlorine or chloramine. "Chloramination is more long-lasting and does not form as many disinfection by-products through the system," says Steve Via, director of federal relations at the American Water Works Association. "Some studies show that chloramination may be more protective against organisms that inhabit biofilms such as Legionella."</p>
Alternative Approaches<p>When he moved to the U.S. from Germany, Prasse says he immediately noticed the bad taste of the water. "You can taste the chlorine here. That's not the case in Germany," he says.</p><p>In his home country, water systems use chlorine — if at all — at lower concentrations and at the very end of treatment. In the Netherlands, <a href="https://dwes.copernicus.org/articles/2/1/2009/dwes-2-1-2009.pdf" target="_blank">chlorine isn't used at all</a> as the risks are considered to outweigh the benefits, says Prasse. He notes the challenge in making a convincing connection between exposure to low concentrations of disinfection by-products and health effects, such as cancer, that can occur decades later. In contrast, exposure to a pathogen can make someone sick very quickly.</p><p>But many countries in Europe have not waited for proof and have taken a precautionary approach to reduce potential risk. The emphasis there is on alternative approaches for primary disinfection such as ozone or <a href="https://www.pbs.org/wgbh/nova/article/eco-friendly-way-disinfect-water-using-light/" target="_blank" rel="noopener noreferrer">ultraviolet light</a>. Reverse osmosis is among the "high-end" options, used to remove organic and inorganics from the water. While expensive, says Prasse, the method of forcing water through a semipermeable membrane is growing in popularity for systems that want to reuse wastewater for drinking water purposes.</p><p>Remucal notes that some treatment technologies may be good at removing a particular type of contaminant while being ineffective at removing another. "We need to think about the whole soup when we think about treatment," she says. What's more, Remucal explains, the mixture of contaminants may impact the body differently than any one chemical on its own. </p><p>Richardson's preferred treatment method is filtering the water with granulated activated carbon, followed by a low dose of chlorine.</p><p>Granulated activated carbon is essentially the same stuff that's in a household filter. (EWG recommends that consumers use a <a href="https://www.ewg.org/tapwater/reviewed-disinfection-byproducts.php#:~:text=EWG%20recommends%20using%20a%20home,as%20trihalomethanes%20and%20haloacetic%20acids." target="_blank" rel="noopener noreferrer">countertop carbon filter</a> to reduce levels of disinfection by-products.) While such a filter "would remove disinfection by-products after they're formed, in the plant they remove precursors before they form by-products," explains Richardson. She coauthored a <a href="https://pubs.acs.org/doi/10.1021/acs.est.9b00023" target="_blank" rel="noopener noreferrer">2019 paper</a> that concluded the treatment method is effective in reducing a wide range of regulated and unregulated disinfection by-products.</p><br>
Greater Cincinnati Water Works installed a granulated activated carbon system in 1992, and is still one of relatively few full-scale plants that uses the technology. Courtesy of Greater Cincinnati Water Works.<p>Despite the technology and its benefits being known for decades, relatively few full-scale plants use granulated active carbon. They often cite its high cost, Richardson says. "They say that, but the city of Cincinnati [Ohio] has not gone bankrupt using it," she says. "So, I'm not buying that argument anymore."</p><p>Greater Cincinnati Water Works installed a granulated activated carbon system in 1992. On a video call in December, Jeff Swertfeger, the superintendent of Greater Cincinnati Water Works, poured grains of what looks like black sand out of a glass tube and into his hand. It was actually crushed coal that has been baked in a furnace. Under a microscope, each grain looks like a sponge, said Swertfeger. When water passes over the carbon grains, he explained, open tunnels and pores provide extensive surface area to absorb contaminants.</p><p>While the granulated activated carbon initially was installed to address chemical spills and other industrial contamination concerns in the Ohio River, Cincinnati's main drinking water source, Swertfeger notes that the substance has turned out to "remove a lot of other stuff, too," including <a href="https://ensia.com/features/drinking-water-contamination-pfas-health/" target="_blank" rel="noopener noreferrer">PFAS</a> and disinfection by-product precursors.</p><p>"We use about one-third the amount of chlorine as we did before. It smells and tastes a lot better," he says. "The use of granulated activated carbon has resulted in lower disinfection by-products across the board."</p><p>Richardson is optimistic about being able to reduce risks from disinfection by-products in the future. "If we're smart, we can still kill those pathogens and lower our chemical disinfection by-product exposure at the same time," she says.</p><p><em>Reposted with permission from </em><em><a href="https://ensia.com/features/drinking-water-disinfection-byproducts-pathogens/" target="_blank">Ensia</a>. </em><a href="https://www.ecowatch.com/r/entryeditor/2649953730#/" target="_self"></a></p>
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