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Pollution - of land, air, freshwater and oceans - is one of the boundaries to human life on Earth.

Chemical pollution

The dystopian lake filled by the world’s tech lust Tim Maughan; BBC Future; 2 Apr 2015

Hidden in an unknown corner of Inner Mongolia is a toxic, nightmarish lake created by our thirst for smartphones, consumer gadgets and green tech

Highly efficient heavy metal ions filter Science Daily; 25 Jan 2016

In November 2015, Brazil experienced an unparalleled environmental disaster. When two dams broke at an iron ore mine, a poisonous cocktail of heavy metals was sent pouring into the Rio Doce, reaching the Atlantic some days later. The consequences were devastating for nature and humans alike: countless fish, birds and animals died, and a quarter of a million people were left without drinking water.

This case demonstrates that water pollution is one of today's most serious global problems. No satisfactory technical solution has been found for the treatment of water contaminated with heavy metals or radioactive substances. Existing methods used to remove water from heavy metals, for example, have several disadvantages: either they are too targeted at a specific element or their filter capacity is too small; additionally, they are often too expensive.

Now, a solution may have been found in a new type of hybrid filter membrane developed in the laboratory of Raffaele Mezzenga, Professor of Food and Soft Materials at ETH Zurich. This technology not only has an extremely simple structure, but also comprises low-cost raw materials, such as whey protein fibres and activated charcoal. Heavy metal ions can be almost completely removed from water in just a single pass through the filter membrane.

Efficient removal of uranium, other heavy metals from water Science Daily; 10 Dec 2013

A new and efficient method for the removal of uranium and other heavy metals from water has been developed at the University of Eastern Finland. Chemec Ltd., a Finnish chemicals industry company, has purchased the rights in the invention and will introduce the method to the commercial markets. Binding metal ions to a solid material, the CH Collector method can be used within the mining industry, and also in the removal of emissions caused by the chemicals and metals processing industries.

Chemec's CH Collector method is a potential solution to issues relating to the dangers and recovery of uranium, which have been a topic of much debate in Finland lately. Uranium is a mildly radioactive and poisonous heavy metal, which is naturally occurring in some parts of the Finnish bedrock. When mining other metals such as gold, uranium may be present as an impurity in mining waste waters. A complete removal of uranium from solutions is difficult due to the fact that uranium takes different forms depending on the acidity of the solution. The removal of other heavy metal emissions such as lead, mercury, cadmium and zinc from waters is also challenging.

Air pollution

Study: More than 6 million could die early from air pollution every year

Choking Our Health Care System With Coal Conca; Forbes

19 April 2016: EU membership delivers cleaner air Stephen Tindale; Climate Answers; 19 Apr 2016

Ozone Pollution Grows, but It Can Be Fixed Dave Levitan (Ensia); Scientific American; 22 Feb 2018


Ground-level ozone, or O
, is a hazard to human health and the environment, causing respiratory problems and exacerbating asthma while also harming some vegetation and wildlife. Created when by-products of combustion interact with sunlight, it may cause more than a million deaths each year around the world, along with tens of billions of dollars in crop losses.

From a technological standpoint, this is a fixable problem. Available — though sometimes costly — solutions for scrubbing ozone precursors from smokestack emissions exist. In fact, the U.S. auto industry has already managed to cut vehicle emissions of ozone-exacerbating pollutants more than 99 percent over a few decades, thanks in large part to regulations that required changes to gasoline formulation as well as engine technology. In the U.S., past progress includes a 31 percent decrease in the national average ozone concentration from 1980 to 2016. Emissions of the precursor pollutants have showed similar declines in other parts of the world such as Europe, but large portions of the population still are at risk of dangerous exposures.

Air pollution and COVID-19

‘Compelling’ evidence air pollution worsens coronavirus – study Damien Carrington, The Guardian, 13 July 2020

Exclusive: best analysis to date indicates significant increases in infections, hospital admissions and deaths

There is “compelling” evidence that air pollution significantly increases coronavirus infections, hospital admissions and deaths, according to the most detailed and comprehensive analysis to date.

The research indicates that a small, single-unit increase in people’s long-term exposure to pollution particles raises infections and admissions by about 10% and deaths by 15%. The study took into account more than 20 other factors, including average population density, age, household size, occupation and obesity.

There is growing evidence from Europe, the US and China that dirty air makes the impact of Covid-19 worse. But the study of the outbreak in the Netherlands is unique because the worst air pollution there is not in cities but in some rural areas, due to intensive livestock farming.

This allows the “big city effect” to be ruled out, which is the idea that high air pollution simply coincides with urban populations whose density and deprivation may make them more susceptible to the virus.

The scientists are clear they have not proven a causal link between air pollution and worse coronavirus impacts. Conclusive evidence will only come with large amounts of data on individual people, which is not yet available, rather than average data for regions as used in the analysis.

But scientists said it was important to do the best research possible as understanding the link may be important in dealing with further Covid-19 outbreaks and could signal where subsequent waves will hit the hardest.

Many scientists agree that air pollution is likely to be increasing the number and severity of Covid-19 infections, as dirty air is already known to inflame the lungs and cause respiratory and heart disease that make people more vulnerable. But not all agree that the evidence so far is good enough to demonstrate a large impact.

“What I was struck by was this really was a strong relationship,” said Prof Matthew Cole, at the University of Birmingham in the UK, who led the research. Unlike most studies to date, the paper has been reviewed by independent scientists and accepted for publication in a journal, Environmental and Resource Economics.

The team concluded: “Using detailed data we find compelling evidence of a positive relationship between air pollution, and particularly [fine particle] concentrations, and Covid-19 cases, hospital admissions and deaths. This relationship persists even after controlling for a wide range of explanatory [factors].”

The most prominent previous study was conducted by Harvard University researchers and found an 8% increase in coronavirus deaths for a single-unit rise in fine particle pollution. Cole said: “We used data at much finer resolution, with the average size of the 355 Dutch municipalities being 95 km2 compared to the 3,130 km2 for a US county.”

“This means we can more precisely capture each region’s characteristics, including pollution exposure,” he said. The new analysis also uses Covid-19 data up to 5 June 2020, allowing it to capture almost the full wave of the epidemic.

An additional factor considered was the Netherlands carnival gatherings that take place in late February, particularly in the livestock farming regions in the south and east of the country. This is where coronavirus cases were highest and where air pollution is highest, due to the ammonia emitted from livestock farms, which forms particle pollution. Coles’ team used statistical methods to estimate the impact of these gatherings. “But it did not knock out the effects of pollution, which I really thought it would,” he said.

Among the other factors taken into account were average income, level of education, smoking, share of population receiving incapacity benefits and closeness to international borders.

“As analyses of a possible link between air pollution and Covid-19 progress we are beginning to see much better studies emerge,” said Prof Frank Kelly, at Imperial College London, UK. “This new study appears to be the best to date.”

He said the work used high quality data and controlled for multiple possible confounding issues. “Further research elsewhere is required to confirm these findings, but we have now reached a point in the pandemic where datasets are robust enough to ask the question,” he said.

Prof Francesca Dominici, who led the Harvard Study, praised the work as “very good” and agreed that it added to her team’s work. She said it was important to examine the relationship between air pollution and Covid-19 outcomes across many countries, as each country’s data would have its own strengths and weaknesses and different confounding factors can be at play.

“Air pollution is not yet getting enough attention because of the slow peer-review process [for academic studies]” Dominici said. “But hopefully as this and other studies are published, the topic will get more attention and most importantly will affect policy.”

However, Prof Mark Goldberg, at McGill University in Canada, warned that averaging data across a region masked the variations among individuals and could mask other potential explanations for the correlation between dirty air and coronavirus. He is concerned that over-interpreting the correlation distracts from other important factors.

“The issue with severe cases is social and economic deprivation – which correlates with air pollution – and [underlying health] conditions,” he said. “I see it in Montreal: the poorest areas with high numbers of people living together, on low incomes and working multiple jobs were hardest hit.”

Cole accepts that only individual-level data will conclusively resolve the question of a link. “We can’t rule out [some unknown factor] until the data gets better. But it’s difficult to know what that would be.”

Ocean pollution

Where Plastic Goes, Coral Disease Follows Andrea Thompson; Scientific American; 30; Jan 2018

In the relatively pristine waters of the Great Barrier Reef marine disease ecologist Joleah Lamb spent years looking for the ways human activities—from pollution that warms the ocean to commercial fishing to scuba diving and other tourist activities—could affect how often the legendary corals off the Australian coast get sick.

One thing she and her team did not see much of was plastic trash. “So it wasn’t something I thought about a lot,” Lamb says. That changed when she and colleagues began studying the reefs off Indonesia, Myanmar and other parts of Southeast Asia. They were floored by the ubiquity of diapers, water bottles and plastic bags littering the fragile ecosystems. The researchers kept a record of the detritus they came across in their work in the region—and the data shows that after plastic comes into contact with a reef, the coral is 20 times more likely to be afflicted by disease.

Schmidt et al

Export of Plastic Debris by Rivers into the Sea Christian Schmidt, Tobias Krauth, Stephan Wagner; Environmental Science and Technology; 11 Oct 2017

A substantial fraction of marine plastic debris originates from land-based sources and rivers potentially act as a major transport pathway for all sizes of plastic debris. We analyzed a global compilation of data on plastic debris in the water column across a wide range of river sizes. Plastic debris loads, both microplastic (particles <5 mm) and macroplastic (particles >5 mm) are positively related to the mismanaged plastic waste (MMPW) generated in the river catchments. This relationship is nonlinear where large rivers with population-rich catchments delivering a disproportionately higher fraction of MMPW into the sea. The 10 top-ranked rivers transport 88–95% of the global load into the sea. Using MMPW as a predictor we calculate the global plastic debris inputs form rivers into the sea to range between 0.41 and 4 × 106 t/y. Due to the limited amount of data high uncertainties were expected and ultimately confirmed. The empirical analysis to quantify plastic loads in rivers can be extended easily by additional potential predictors other than MMPW, for example, hydrological conditions.

Rivers carry plastic debris into the sea press release; Helmholtz Centre for Environmental Research; 17 Oct 2017

UFZ researchers have proven that large river systems are the main culprits for plastic pollution in the oceans

Every year, millions of tonnes of plastic debris ends up in the sea - a global environmental problem with unforeseeable ecological consequences. The path taken by plastic to reach the sea must be elucidated before it will be possible to reduce the volume of plastic input. To date, there was only little information available on this. It has now been followed up by an interdisciplinary research team who were able to show that plastic debris is primarily carried into the sea by large rivers.

In the meantime, minute plastic particles can be found in the water in virtually every sea and river. This constitutes a serious and growing global environmental problem. There are enormous quantities of input each year and plastic weathers only very slowly. Marine life can be harmed by the tiny plastic particles floating in the water. One example of how this happens is when fish, seabirds or marine mammals mistake the particles for food and consume them. "It is still impossible to foresee the ecological consequences of this. One thing is certain, however: this situation cannot continue," says Dr. Christian Schmidt, a hydrogeologist at the UFZ. "But as it is impossible to clean up the plastic debris that is already in the oceans, we must take precautions and reduce the input of plastic quickly and efficiently."

However, in order to take practical measures to reduce plastic input, it will be necessary to answer the initial questions: Where does all the plastic come from anyhow? And how does it get into the sea? Schmidt and his team addressed these questions in a study that recently appeared in the current issue of "Environmental Science & Technology" journal. For this purpose, the researchers analysed various scientific studies that examined the plastic load - that is the quantity of plastic carried by the water - in rivers. They converted the results of the studies into mutually comparable datasets and determined the ratio of these figures to the quantity of waste that is not disposed of properly in the respective catchment area. "We were able to demonstrate that there is a definite correlation in this respect," says Schmidt. "The more waste there is in a catchment area that is not disposed of properly, the more plastic ultimately ends up in the river and takes this route to the sea." In this context, large rivers obviously play a particularly large role - not only because they also carry a comparatively large volume of waste on account of their larger discharge. Schmidt says, "the concentrations of plastic, i.e. the quantity of plastic per cubic metre of water are significantly higher in large rivers than small ones. The plastic loads consequently increase at a disproportionately higher rate than the size of the river."

The researchers have also calculated that the ten river systems with the highest plastic loads (eight of them are in Asia and two in Africa) - areas in which hundreds of millions of people live, in some cases - are responsible for around 90 percent of the global input of plastic into the sea. "Halving the plastic input from the catchment areas of these rivers would already be a major success", says Schmidt. "To achieve this, it will be necessary to improve the waste management and raise public awareness for the issue. We hope that our study will make a contribution to a positive development so that the plastic problem in our oceans can be curbed in the long run."

In future investigations, the UFZ team intends to find out how long plastic debris takes to reach the sea once it gets into a river. Does it take only a few months or even decades? "It is important to be aware of this as the impact of a measure becomes apparent only with a corresponding time delay as existing pollution has yet to be washed into the sea", explains Schmidt. "Only when we are aware of roughly how long plastic debris remains in the respective river system will it also be possible to assess a measure to improve the waste management system in the catchment area."