About 700 million years ago, the Earth cooled a lot that scientists consider that massive layers of ice enveloped the whole planet like an enormous snowball. This global deep freeze, referred to as snowball earthendured for Tens of hundreds of thousands of years.

Yet miraculously youth not only sustained, but thrived. As the ice melted and the bottom thawed, Complex multicellular life emergedwhich eventually led to the life forms we all know today.

The Snowball Earth Hypothesis is essentially based on evidence from sedimentary rocks exposed in areas were once along the coasts and shallow seas as well Climate modeling. Physical evidence that ice sheets covered the inside of continents in warm equatorial regions had previously eluded scientists.

In latest research Published within the Proceedings of the National Academy of Sciences, our team of geologists describe the missing link present in an unusual siliceous sandstone trapped within the granite that forms Pikes Peak in Colorado.

Solve a snowball earth puzzle on a mountain

Pikes Peak, originally called Tavá Kaa-vi Founded by the Ute people, these remarkable rocks are given their ancestral name, Tava. They are consisting of solidified sand injectiteswhich formed in a fashion just like a medical injection when sand-rich fluid was forced into underlying rock.

One possible explanation for the formation of those enigmatic sandstones is the big pressure of an overlying snowball-earth ice sheet, which pushes sediment mixed with meltwater into the weakened rock below.

One obstacle to testing this concept, nonetheless, was the shortage of an age statement for the rocks that might indicate when the correct geological conditions existed for sand injection.

We found a approach to solve this mystery using iron veins found along the Tava injectites near Pikes Peak and elsewhere in Colorado.

Iron minerals contain very small amounts of naturally occurring radioactive elements, including uranium, which evolve slowly decays into the element lead at a known rate. Current advances in Laser-based radiometric dating allowed us to measure the ratio of uranium to steer isotopes within the iron oxide mineral hematite and thus learn the way way back each crystal formed.

The iron veins appear to have formed each before and after the sand was injected into the Colorado bedrock: we found hematite and quartz veins cutting through each Tava dikes and intersected by Tava dikes. This allowed us to find out an age range for the sand injectites, which should have formed 690 to 660 million years ago.

So what happened?

The timeframe signifies that these sandstones were formed in the course of the Cryogenic period, 720 to 635 million years ago. The name is derived from “cold birth” in ancient Greek and is synonymous with climate change and the disruption of life on our planet – including Snowball Earth.

While the causes of the intense cold on the time are controversial, there are prevailing theories Changes within the activity of tectonic platesThis includes the discharge of particles into the atmosphere that reflect sunlight away from the Earth. Finally, a Accumulation of carbon dioxide from volcanic outgassing could have warmed the planet again.

The tava found on Pikes Peak is believed to have formed near the equator in the center of a volcano ancient continent called Laurentiawhich steadily moved over time and over long tectonic cycles to its present northern position in North America.

The origin of the Tava rocks is controversial for over 125 yearsbut latest technology allowed us to conclusively link it to the cryogenic Snowball Earth period for the primary time.

The scenario we imagine for sand injection looks something like this:

An enormous ice sheet with areas of geothermal heating at its base produced meltwater that mixed with quartz-rich sediment below. The weight of the ice sheet created enormous pressures that pushed this sandy fluid into bedrock that had already been weakened over hundreds of thousands of years. Similar to today's fracking for natural gas or oil, the pressure cracked the rock and pushed the sandy meltwater in, eventually creating the injectites we see today.

Clues to a different geological mystery

Not only do the brand new findings further support the worldwide Snowball Earth hypothesis, however the presence of Tava injectites in weak, fractured rocks once overlain by ice sheets also provides clues to other geological phenomena.

Time gaps within the rock record brought on by erosion are known as discrepancies can now be seen throughout the United States, most famously on the Grand Canyon, where in places over a billion years of time are missing. Unconformities occur when a sustained period of abrasion prevents the formation of newer rock layers, leaving an unconformable contact.

Our results show that a big unconformity should have formed near Pikes Peak prior to the cryogenic Snowball Earth. This contradicts hypotheses that attribute the formation of the Great Unconformity to this large-scale erosion through snowball earth ice sheets themselves.

We hope that the secrets of those elusive cryogenic rocks in Colorado will result in the invention of additional terrestrial records of Snowball Earth. Such findings may help develop a clearer picture of our planet during climate extremes and the processes that led to the habitable planet we continue to exist today.

Nearly 25,000 acres (10,000 hectares) of rice are grown in Florida each summer. Agricultural area of ​​the Evergladesan area of ​​roughly 2,800 square kilometers south of Lake Okeechobee.

Farming here requires an important deal of sensitivity. The area has lost almost 1.8 metres of soil within the last century on account of Process called soil subsidence.

One option to slow this subsidence and preserve the nutrient-rich soil is to flood the world during Florida's rainy season and use the fields to grow rice. The fields are flooded with water from the adjoining canals. Once the water dries up or seeps away, the rice is harvested.

The Conversation asked Associate Professor Jehangir Bhadha, a Soil sustainability expert on the University of Florida, how the university got here to grow rice and what advantages this brings to the environment.

What is the story behind rice cultivation within the Everglades?

In the Fifties, rice was grown for a short while within the Everglades Agricultural Area, but the world was limited to about 2,000 acres (800 hectares).

Then got here the invention of a rice virus in Florida called Hoja Blanca or white leafwhich causes the plants to wither and even kill them. This virus was first discovered within the late Fifties in Colombia and Venezuela.

Rice made a comeback in Florida in 1977 after farmers within the Everglades Agricultural Area demonstrated that it grown on sugar cane fields in the course of the summer fallow period from May to August – when it is simply too hot and wet to grow vegetables in South Florida. By this time, Hoja Blanca disease was under control and recent resistant rice varieties were being developed.

In late spring and summer, greater than 20,000 hectares of fallow sugarcane land within the Everglades Agricultural Area can be found for rice cultivation. In 2023 About half of this area was planted with rice.The remaining land is either left fallow or flooded but doesn’t produce rice – a practice commonly known as “Fallow water flooding.”

On average, every hectare cultivated yields approx. 2 tons (1,800 kilograms) of rice.

What makes rice cultivation on this area so special?

Rice cultivation within the Everglades Agricultural Area doesn’t require initial fertilization with nitrogen, phosphorus or potassium since the region's soils are highly organic and nutrient-rich.

The area covers almost 450,000 acres (180,000 hectares) organic soils generally known as histosols. These soils contain as much as 80% organic matter, making them unique to the region and a vital resource for its thriving agriculture. Histosols are sometimes called bathroom or peat soils.

The Histosols of South Florida were formed over a period of several thousand years as organic material gathered faster than it could decompose within the flooded sawgrass prairies that flourished in the world south of Lake Okeechobee.

But for the reason that land here was drained for agriculture within the early twentieth century, organic material has been decomposing faster than it may possibly grow back. This is especially on account of microbially mediated oxidation, which occurs when organic material is slowly decomposed and consumed by microbes, resulting in a gradual lack of soil and a lowering of surface elevation.

The soil depth on this area varies from just a few centimeters to as much as 1.5 meters. Beneath the Histosols lies hard limestone rock that just isn’t suitable for agriculture. In many places the limestone rock is exposed on the surface or parts of it are incorporated into the soil.

What contribution does rice cultivation make to soil health there?

By flooding the fields for long periods of time, farmers suppress each the microbial activity that results in oxidation and the hatching of Pests. It also increases the water holding capability of the soilwhich allows for higher moisture retention within the drier seasons.

The improved soil health advantages the sugar cane crop and maximizes the lifespan of the soil.

The cultivation of flooded rice has also proven to be Attracting waders How great white heron, Great Egret And Glossy-headed Ibis.

What work is your team currently doing?

In the last 15 years, more rice and more varieties of rice have been grown. While in 2008 only two dominant varieties were grown on around 4,800 hectares, by 2023 there have been already greater than 10 varieties on 9,300 hectares.

To ensure a continuous supply of latest varieties, researchers and others University of Florida Institute of Food and Agricultural Sciencesalong with Company: Florida Rice Growers Inc.conduct annual rice variety trials to guage recent or existing varieties in South Florida. The goal of the trials is to discover high-yielding, disease-resistant rice varieties which might be compatible with the region's subtropical climate and highly organic soils.

Every summer University of Florida IFAS Extension and the Research Faculty hold a rice field day dedicated to presenting their current research.

As spring turns to summer within the United States, children are spending more time outdoors. Playing outside is healthy in some ways, nevertheless it also carries some risks. One that many families is probably not aware of is lead contamination in soil, which continues to be a significant issue, especially in urban areas.

Children can Exposed to guide by swallowing or inhaling soil while playing. Young children often put their hands of their mouths and can have dirt on their hands. Children and pets may also carry lead dust from soil indoors. And anyone who eats fruit or vegetables grown on contaminated soil can ingest lead.

In early 2024, the US Environmental Protection Agency lowered the Screening levels for lead in residential floors from 400 ppm – a typical that’s greater than 30 years old – to 200 ppm. This safer, lower level reflects the present understanding that soil is a major source of lead exposure for youngsters.

EPA officials said that in homes exposed to guide from multiple sources, the agency generally takes a more conservative approach 100 parts per million Screening level.

This latest level just isn’t a remediation standard; it’s a threshold at which EPA will make site-specific decisions about methods to protect people there. Actions may include providing details about lead in soil, making recommendations to cut back exposure, or removing the lead-containing soil and replacing it with clean soil.

The standard is meant to assist EPA evaluate residential soils around contaminated sites under two federal laws. Superfund Act deals with hazardous waste that was improperly generated or disposed of before 1976, while the Resource Conservation and Recovery Act regulates the production and disposal of hazardous waste from this 12 months. More than 4,000 locations across the country are currently being cleared up under these two laws.

I study Lead poisoning in the town amongst children from soil and other sources, and I even have worked with colleagues to research tens of 1000’s of soil samples collected by researchers and Citizens within the USAThis work just isn’t yet complete, but our newly published results show that under the brand new EPA standard, potentially harmful lead contamination from soil widespread than many individuals, including officials, consider. Reducing this risk shall be a really long-term endeavor.

A toxic legacy

Lead contamination has plagued communities across the United States, particularly low-income communities and communities of color. Many aspects have contributed to this, including lead in Gasoline, water pipes and paintIn addition, redlining and other policies trap vulnerable families in substandard housing, often painted with lead paint and positioned in areas with high levels of traffic and industrial pollution.

Lead affects many parts of the bodyincluding the brain and central nervous system. High lead exposure in childhood can result in poorer educational outcomes and lower income potential.

Since the federal government began to severely restrict the production and use of lead within the Seventies, the share of kids within the United States who’re considered lead-exposed by today's standards has dropped dramatically. This implies that for tens of hundreds of thousands of kids within the United States, the danger of suffering cognitive impairment from lead exposure has been greatly reduced. In the Seventies, this figure was nearly 100%; today it’s about 1%, which is about 500,000 children.

Yet many urban children are still exposed to guide at levels which might be hazardous to their health, and soil contamination just isn’t addressed by laws that reduce other sources of lead. Lead in soil is residue from decomposed lead paint, pollution from cars which have burned leaded gasoline for a long time, and emissions from factories and industrial plants.

Lead in soil is a widespread risk

Our nationwide evaluation of samples collected in 16 cities found that out of 15,595 household soil samples, 12.3% – or one in eight – exceeded the old nationwide test value of 400 ppm. If the usual is reduced to the proposed value of 200 ppm, 23.7% of households – or almost one in 4 – shall be vulnerable to lead exposure.

These samples were typically collected in groups, with one sample positioned near the outside partitions of a house, where the best lead levels within the soil are expected, one other within the yard, and a 3rd near the road, where elevated lead levels may additionally be found.

When extrapolated to the whole country, our results suggest that as much as about 29 million of the 123.6 million households counted within the 2020 Census may very well be exposed to soil lead contamination and may take steps to mitigate it. Using the EPA's ambitious 100 ppm goal, our evaluation shows that about 40.2% of households may very well be affected—that's nearly 50 million households nationwide.

Not all communities in our study have an analogous risk profile. In Chicago, for instance, 52.8% of the household deposits we tested contained greater than 200 ppm of lead. Samples from parts of several mid-sized cities, including Springfield, Massachusetts, and Chattanooga and Memphis, Tennessee, showed comparable percentages.

It is difficult to totally determine soil lead contamination in specific cities for several reasons. First, the citizen science dataset we used for our evaluation was collected by private residents following specific guidelines somewhat than the rigorous scientific protocols that the EPA would follow. Second, there isn’t a other systematic, comprehensive measurement of lead levels in household soils within the United States that may very well be used to evaluate the accuracy of the community science samples.

Ground cover as a primary step

Because data on lead levels in soil are limited, it just isn’t yet possible to find out which households are at best potential risk. Without this information, the true cost of reducing this problem can be unknown.

A whole remediation, during which contaminated soils are removed and replaced with clean soils, may be achieved between $10,000 to $30,000 per householdTypically, the homeowner is answerable for the fee of one of these voluntary cleanup, but some states have assistance programs.

At this rate, the fee of remediating all homes nationwide whose soil we project to be above the brand new EPA standard would range from $290 billion to over $1.1 trillion. Soil remediation in homes involves many steps, including Soil testing and dirt monitoringIf poorly executed, lead-contaminated soil and dirt may be spread beyond the remediation site.

Given these projected costs, my colleagues and I don’t expect such a program to be proposed within the near future. However, there may be a faster and less expensive strategy: covering existing soils with clean soil or mulch. While this just isn’t an ideal solution, it does solve the immediate lead exposure problem for youngsters living in these areas.

Covering just isn’t a everlasting solution because soil cover may be disturbed, making lead-containing soils an lively risk again. But even covering a contaminated site with clean soils will permanently dilute the location's overall lead concentration. Almost the entire lead deposited by human activities is absorbed into the top 10 inches of soilIf you add one other 25 cm of unpolluted soil, the lead concentration within the soil shall be reduced by half.

It's a cliché but true that the answer to pollution often lies in dilution. I see this straightforward strategy as a way for cities to right away address their latest lead problem.

Nearly half of American tap water comprises PFAS, or perfluorinated and polyfluorinated alkyl substances. These “forever chemicals” are present in 1000’s of products, from clothing and cosmetics to cleansing productsand are linked to Cancer, liver damage, high cholesterol and asthma.

Dr. Jessica RayAssistant Professor of Civil and Environmental Engineering on the University of Washington, explains what PFAS arehow scientists try to remove them from the environment and what you’ll be able to do to cut back the impact of PFAS on your personal health.

The Conversation has worked with SciLine to bring you highlights from the discussion, edited for brevity and clarity.

What are PFAS and the way are they used?

Jessica Ray: PFAS are a category of 1000’s of synthetic chemicals originally manufactured within the Nineteen Fifties and heavily usedThey were the energetic ingredient in fire-fighting foams used on military bases to fight aircraft fires.

Since then they’ve been utilized in many applications and consumer products – Shampoos, dental floss, nail polish. They are utilized in waxy coatings of food containers. They are also used as non-stick coatings, for instance in cookware. They are utilized in outerwear to guard against rain.

Why are PFAS called “forever chemicals”?

Jessica Ray: It is difficult to detect PFAS naturally within the environment and even during processes comparable to Water supply.

How do PFAS spread within the environment?

Jessica Ray: Unfortunately, PFAS wish to follow solid surfaces like soil. They can dissolve in water and enter the Earth's atmosphere. And because PFAS can go through air, water and soil, humans and animals will be exposed to them in a Variety of possibilities.

For example, if PFAS are present in seawater and the fish ingest them and change into contaminated with PFAS and we then eat those fish, we’re exposed to PFAS. And unfortunately Researchers have discovered PFAS In many, many various drinking water sources worldwide. Not only surface water and groundwater, but in addition bottled water.

What are the health effects of PFAS?

Jessica Ray: PFAS have been linked to Liver tissue damage and kidney cancerIf a fetus is exposed to PFAS while pregnant, can result in low birth weight And accelerated pubertyPFAS are also related to immune system impairments.

How can we reduce personal exposure to PFAS?

Jessica Ray: You can Number of thingsWhen you cook, you’ll be able to buy and use chrome steel or forged iron cookware. This tried and tested cookware mustn’t contain PFAS.

Also search for products that explicitly state that they’re PFAS-free. And you would buy organic products, which must have lower PFAS levels. It will likely be necessary to search out ways to cut back PFAS levels within the environment and drinking water, given the Environmental Protection Agency's decision in April 2024, Regulation of several PFAS in drinking water.

How can we remove PFAS from our drinking water?

Jessica Ray: A handful of corporations essentially sell a version of a Brita water filter that specifically targets PFAS, but generally, using a Brita or Pur water filter at home should help reduce exposure not only to PFAS, but in addition to other contaminants which will even be present within the drinking water that comes out of the faucet at home.

What about your research on removing PFAS from water?

Jessica Ray: My research group is investigating two different approaches to treating PFAS in water. One approach is Separating PFAS from waterThe other is, Destroy PFAS in water.

In the separation approaches, we examine existing water treatment processes utilized in drinking water and wastewater treatment after which try to switch these processes to specifically capture PFAS within the water while concurrently checking out other contaminants that could be present within the water.

How is your group attempting to improve PFAS filtration?

Jessica Ray: When you filter your water at home with a filter cartridge, you’ll be able to remove a wide range of contaminants. These contaminants can include heavy metals or other pollutants dissolved within the water.

But often PFAS in drinking water sources often occur in very, very low concentrationswhile other contaminants occur at much higher levels. Filters have only a limited variety of adsorption sites to bind contaminants, so it is extremely likely that the adsorption sites will likely be full before the PFAS will be faraway from the water.

One approach we're taking is developing recent adsorbents that specifically goal PFAS. My group has been developing this material for the past few years. And we're talking to individuals who will help us commercialize this technology so that customers can use these kinds of point-of-use treatments to guard themselves from PFAS. It's hard to say exactly how long it is going to take for the treatments to be commercially available – perhaps a 12 months or two.

Are there safer alternatives to PFAS?

Jessica Ray: Researchers are investigating the so-called green chemistry – Developing chemicals that behave similarly to PFAS but will not be as toxic and break down within the environment. So there may be hope for the longer term.

Watch the full interview to listen to more.

SciLine is a free service of the nonprofit American Association for the Advancement of Science that helps journalists incorporate scientific evidence and experts into their news stories.