Tag Archives: Water

London Underground polluted with metallic particles small enough to enter human bloodstream

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The London Underground is polluted with ultrafine metallic particles small enough to end up in the human bloodstream, according to University of Cambridge researchers. These particles are so small that they are likely being underestimated in surveys of pollution in the world’s oldest metro system.

The researchers carried out a new type of pollution analysis, using magnetism to study dust samples from Underground ticket halls, platforms and operator cabins.

The team found that the samples contained high levels of a type of iron oxide called maghemite. Since it takes time for iron to oxidise into maghemite, the results suggest that pollution particles are suspended for long periods, due to poor ventilation throughout the Underground, particularly on station platforms.

Some of the particles are as small as five nanometres in diameter: small enough to be inhaled and end up in the bloodstream, but too small to be captured by typical methods of pollution monitoring. However, it is not clear whether these particles pose a health risk.

Other studies have looked at overall pollution levels on the Underground and the associated health risks, but this is the first time that the size and type of particles has been analysed in detail. The researchers suggest that periodic removal of dust from Underground tunnels, as well as magnetic monitoring of pollution levels, could improve air quality throughout the network. Their results are reported in the journal Scientific Reports.

The London Underground carries five million passengers per day. Multiple studies have shown that air pollution levels on the Underground are higher than those in London more broadly, and beyond the World Health Organization’s (WHO) defined limits. Earlier studies have also suggested that most of the particulate matter on the Underground is generated as the wheels, tracks and brakes grind against one another, throwing up tiny, iron-rich particles.

“Since most of these air pollution particles are metallic, the Underground is an ideal place to test whether magnetism can be an effective way to monitor pollution,” said Professor Richard Harrison from Cambridge’s Department of Earth Sciences, the paper’s senior author. “Normally, we study magnetism as it relates to planets, but we decided to explore how those techniques could be applied to different areas, including air pollution.”

Pollution levels are normally monitored using standard air filters, but these cannot capture ultrafine particles, and they do not detect what kinds of particles are contained within the particulate matter.

“I started studying environmental magnetism as part of my PhD, looking at whether low-cost monitoring techniques could be used to characterise pollution levels and sources,” said lead author Hassan Sheikh from Cambridge’s Department of Earth Sciences. “The Underground is a well-defined micro-environment, so it’s an ideal place to do this type of study.”

Working with colleagues from Cambridge’s Department of Materials Science and Metallurgy, Sheikh and Harrison analysed 39 dust samples from the London Underground, provided by Transport for London (TfL). The samples were collected in 2019 and 2021 from platforms, ticket halls, and train operator cabins on the Piccadilly, Northern, Central, Bakerloo, Victoria, Northern, District and Jubilee lines. The sampling included major stations such as King’s Cross St Pancras, Paddington, and Oxford Circus.

The researchers used magnetic fingerprinting, 3D imaging and nanoscale microscopy to characterise the structure, size, shape, composition and magnetic properties of particles contained in the samples. Earlier studies have shown that 50% of the pollution particles in the Underground are iron-rich, but the Cambridge team were able to look in much closer detail. They found a high abundance of maghemite particles, ranging in diameter from five to 500 nanometres, and with an average diameter of 10 nanometres. Some particles formed larger clusters with diameters between 100 and 2,000 nanometres.

“The abundance of these very fine particles was surprising,” said Sheikh. “The magnetic properties of iron oxides fundamentally change as the particle size changes. In addition, the size range where those changes happen is the same as where air pollution becomes a health risk.”

While the researchers did not look at whether these maghemite particles pose a direct health risk, they say that their characterisation methods could be useful in future studies.

“If you’re going to answer the question of whether these particles are bad for your health, you first need to know what the particles are made of and what their properties are,” said Sheikh.

“Our techniques give a much more refined picture of pollution in the Underground,” said Harrison. “We can measure particles that are small enough to be inhaled and enter the bloodstream. Typical pollution monitoring doesn’t give you a good picture of the very small stuff.”

The researchers say that due to poor ventilation in the Underground, iron-rich dust can be resuspended in the air when trains arrive at platforms, making the air quality on platforms worse than in ticket halls or in operator cabins.

Given the magnetic nature of the resuspended dust, the researchers suggest that an efficient removal system might be magnetic filters in ventilation, cleaning of the tracks and tunnel walls, or placing screen doors between platforms and trains.

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Simple method destroys dangerous ‘forever chemicals,’ making water safe

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Key takeaways:

  • World’s water tainted. Synthetic PFAS, which have been linked to cancer and other diseases, have contaminated nearly every drop of water on the planet.
  • Unbreakable bond. These chemicals contain a carbon-fluorine bond that is almost impossible to break, making it extremely difficult to eradicate them from water supplies.
  • Off with their heads! Researchers devised a “guillotine” solution that uses moderate heat and inexpensive reagents to remove the “heads” of PFAS, initiating their destruction.

If you’re despairing at recent reports that Earth’s water sources have been thoroughly infested with hazardous human-made chemicals called PFAS that can last for thousands of years, making even rainwater unsafe to drink, there’s a spot of good news.

Chemists at UCLA and Northwestern University have developed a simple way to break down almost a dozen types of these nearly indestructible “forever chemicals” at relatively low temperatures with no harmful byproducts.

Simple method destroys dangerous ‘forever chemicals,’ making water safe

In a paper published today in the journal Science, the researchers show that in water heated to just 176 to 248 degrees Fahrenheit, common, inexpensive solvents and reagents severed molecular bonds in PFAS that are among the strongest known and initiated a chemical reaction that “gradually nibbled away at the molecule” until it was gone, said UCLA distinguished research professor and co-corresponding author Kendall Houk.

The simple technology, the comparatively low temperatures and the lack of harmful byproducts mean there is no limit to how much water can be processed at once, Houk added. The technology could eventually make it easier for water treatment plants to remove PFAS from drinking water.

Per- and polyfluoroalkyl substances­ — PFAS for short — are a class of around 12,000 synthetic chemicals that have been used since the 1940s in nonstick cookware, waterproof makeup, shampoos, electronics, food packaging and countless other products. They contain a bond between carbon and fluorine atoms that nothing in nature can break.

PFAS used in shampoos

When these chemicals leach into the environment through manufacturing or everyday product use, they become part of the Earth’s water cycle. Over the past 70 years, PFAS have contaminated virtually every drop of water on the planet, and their strong carbon-fluorine bond allows them to pass through most water treatment systems completely unharmed. They can accumulate in the tissues of people and animals over time and cause harm in ways that scientists are just beginning to understand. Certain cancers and thyroid diseases, for example, are associated with PFAS.

For these reasons, finding ways to remove PFAS from water has become particularly urgent. Scientists are experimenting with many remediation technologies, but most of them require extremely high temperatures, special chemicals or ultraviolet light and sometimes produce byproducts that are also harmful and require additional steps to remove.

How to detect nanoplastics present in air

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Large pieces of plastic can break down into nanosized particles that often find their way into the soil and water. Perhaps less well known is that they can also float in the air. It’s unclear how nanoplastics impact human health, but animal studies suggest they’re potentially harmful. As a step toward better understanding the prevalence of airborne nanoplastics, researchers have developed a sensor that detects these particles and determines the types, amounts and sizes of the plastics using colorful carbon dot films.

The researchers will present their results today at the fall meeting of the American Chemical Society (ACS). ACS Fall 2022 is a hybrid meeting being held virtually and in-person Aug. 21–25, with on-demand access available Aug. 26–Sept. 9. The meeting features nearly 11,000 presentations on a wide range of science topics.

“Nanoplastics are a major concern if they’re in the air that you breathe, getting into your lungs and potentially causing health problems,” says Raz Jelinek, Ph.D., the project’s principal investigator. “A simple, inexpensive detector like ours could have huge implications, and someday alert people to the presence of nanoplastics in the air, allowing them to take action.”

Of the many well-documented risks of dirty air, one potential danger is lesser known: chronic kidney disease. Learn about new research and how to protect yourself. CREDIT: Michigan Medicine

Millions of tons of plastic are produced and thrown away each year. Some plastic materials slowly erode while they’re being used or after being disposed of, polluting the surrounding environment with micro- and nanosized particles. Nanoplastics are so small — generally less than 1-µm wide — and light that they can even float in the air, where people can then unknowingly breathe them in. Animal studies suggest that ingesting and inhaling these nanoparticles may have damaging effects. Therefore, it could be helpful to know the levels of airborne nanoplastic pollution in the environment.

Previously, Jelinek’s research team at Ben-Gurion University of the Negev developed an electronic nose or “e-nose” for monitoring the presence of bacteria by adsorbing and sensing the unique combination of gas vapor molecules that they release. The researchers wanted to see if this same carbon-dot-based technology could be adapted to create a sensitive nanoplastic sensor for continuous environmental monitoring.

Carbon dots are formed when a starting material that contains lots of carbon, such as sugar or other organic matter, is heated at a moderate temperature for several hours, says Jelinek. This process can even be done using a conventional microwave. During heating, the carbon-containing material develops into colorful, and often fluorescent, nanometer-size particles called “carbon dots.” And by changing the starting material, the carbon dots can have different surface properties that can attract various molecules.

To create the bacterial e-nose, the team spread thin layers of different carbon dots onto tiny electrodes, each the size of a fingernail. They used interdigitated electrodes, which have two sides with interspersed comb-like structures. Between the two sides, an electric field develops, and the stored charge is called capacitance. “When something happens to the carbon dots — either they adsorb gas molecules or nanoplastic pieces — then there is a change of capacitance, which we can easily measure,” says Jelinek.

Then the researchers tested a proof-of-concept sensor for nanoplastics in the air, choosing carbon dots that would adsorb common types of plastic — polystyrene, polypropylene and poly(methyl methacrylate). In experiments, nanoscale plastic particles were aerosolized, making them float in the air. And when electrodes coated with carbon-dot films were exposed to the airborne nanoplastics, the team observed signals that were different for each type of material, says Jelinek. Because the number of nanoplastics in the air affects the intensity of the signal generated, Jelinek adds that currently, the sensor can report the amount of particles from a certain plastic type either above or below a predetermined concentration threshold. Additionally, when polystyrene particles in three sizes — 100-nm wide, 200-nm wide and 300-nm wide — were aerosolized, the sensor’s signal intensity was directly related to the particles’ size.

The team’s next step is to see if their system can distinguish the types of plastic in mixtures of nanoparticles. Just as the combination of carbon dot films in the bacterial e-nose distinguished between gases with differing polarities, Jelinek says it’s likely that they could tweak the nanoplastic sensor to differentiate between additional types and sizes of nanoplastics. The capability to detect different plastics based on their surface properties would make nanoplastic sensors useful for tracking these particles in schools, office buildings, homes and outdoors, he says.

Diamond impurities indicate water flows deep in Earth’s mantle too

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A scientist from the University of Nevada, Las Vegas, has discovered the first direct evidence that fluid water pockets may exist as far as 500 miles deep into the Earth’s mantle.
Impurities in diamond have no value in the jewelry business but for UNLV geoscientist Oliver Tschauner and his colleagues, diamonds pushed up from the Earth’s interior had traces of unique crystallized water called Ice-VII, as they may hold the key to understanding the inner workings of our planet.

The study, “Ice-VII inclusions in Diamonds: Evidence for aqueous fluid in Earth’s deep Mantle,” was published  in the journal Science. For his study, Tschauner used diamonds found in China, the Republic of South Africa, and Botswana that surged up from inside Earth. “This shows that this is a global phenomenon,” the professor said.

Scientists theorize the diamonds used in the study, were born in the mantle under temperatures reaching more than 1,000-degrees Fahrenheit. The mantle – which makes up more than 80 percent of the Earth’s volume – is made of silicate minerals containing iron, aluminum, and calcium among others.

And now we can add water to the list.

The discovery of Ice-VII in the diamonds is the first known natural occurrence of the aqueous fluid from the deep mantle. Ice-VII had been found in prior lab testing of materials under intense pressure. Tschauner also found that while under the confines of hardened diamonds found on the surface of the planet, Ice-VII is solid. But in the mantel, it is liquid.

“These discoveries are important in understanding that water-rich regions in the Earth’s interior can play a role in the global water budget and the movement of heat-generating radioactive elements,” Tschauner said. This discovery can help scientists create new, more accurate models of what’s going on inside the Earth, specifically how and where heat is generated under the Earth’s crust.

In other words: “It’s another piece of the puzzle in understanding how our planet works,” Tschauner said.Of course, as it often goes with discoveries, this one was found by accident, explained Tschauner. “We were looking for carbon dioxide,” he said. “We’re still looking for it, actually,”

Cabinet Approves MoU between India, EU on Water

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The Union Cabinet under PM Narendra Modi has given its approval for the signing of MoU between India and European Union in the field of water resources.

The MoU envisages strengthening the technological, scientific and management capabilities of India and the European Union in the field of water management on the basis of equality, reciprocity and mutual benefit. It provides technical exchange on water issues, including on integrated water resource management plans within river basins and through study visits.

The MoU aims to identify key environmental issues and approaches to sustainable development where exchange of experiences and cooperation could be mutually beneficial to strengthen and further develop cooperation between India and the European Union in the field of water management.

The pact envisions a more sustainable management of water resources in India with an objective of tackling the challenges posed by water management in the context of growing population, competing water demands and a changing climate. A Joint Working Group shall be formed to monitor the activities to be carried out in fulfillment of the MoU.

The Ministry of Water Resources, River Development and Ganga Rejuvenation has been envisaging bilateral cooperation with other countries in water resources development and management through sharing of policy and technical expertise, conducting of training courses, workshops, scientific and technical symposia, exchange of experts and study tours.

Keeping in view the success of the European Union in distribution of water resources, water pricing, water use efficiency by encouraging the changes in agricultural practices necessary to protect water resources and quality, such as switching to less water-demanding crops, etc., it has been decided to have an agreement with Israel to benefit from their experience and expertise.

The EU States have adopted water pricing policies to provide adequate incentives for users to use water resources efficiently thereby contributing to environmental objectives.