Tag Archives: nitrogen

City Traffic.

New research says traffic exhaust is giving millions of kids asthma all around the world

Traffic-associated pollution leads to roughly 4 million cases of asthma in children worldwide each year, a new study reports.

City Traffic.

Image via Pixabay.

The team looked at 125 cities around the world, keeping track of the nitrogen oxide (NO2) levels in their air, and how it related to new pediatric cases of asthma. The study, based on data from 2010 to 2015, estimates that 4 million children worldwide develop asthma each year due to NO2, with 64% of these new cases occurring in urban areas.

The gas accounted for anywhere between 6% (Orlu, Nigeria) to 48% (Shanghai, China) of these cases, the authors report. Overall, NO2’s contribution to new cases of pediatric asthma exceeded 20% in 92 cities, they add, in both developed and emerging economies.

Bad air

“Our findings suggest that millions of new cases of pediatric asthma could be prevented in cities around the world by reducing air pollution,” said Susan C. Anenberg, PhD, an associate professor of environmental and occupational health at Milken Institute SPH, and the study’s senior author.

“Improving access to cleaner forms of transportation, like electrified public transport and active commuting by cycling and walking, would not only bring down NO2 levels, but would also reduce asthma, enhance physical fitness, and cut greenhouse gas emissions.”

Asthma is a chronic disease that involves inflammation of the lung’s airways, making it hard (sometimes impossible) to breathe. It is estimated that 235 million people worldwide currently have asthma, varying in intensity from wheezing to life-threatening attacks. This study is the first to take a look at how traffic-related nitrogen dioxide fits into the asthma picture. The work relied on a method that takes into account high exposures to NO2  that occur near busy roads, Anenberg explains.

For the study, the team linked together global datasets of NO2 concentrations,  population distributions, and asthma incidence rates with epidemiological evidence relating traffic-derived NO2 pollution with asthma development in kids. This wealth of data allowed the team to estimate how many new cases of pediatric asthma are attributable to NO2 pollution in the 194 countries and 125 major cities they studied.

Here are some key takeaways:

  • Roughly 4 million children developed asthma, each year, from 2010 to 2015 due to NO2 pollution (primarily from motor vehicle exhaust).
  • NO2 accounted for between 6% to 48% of pediatric asthma incidence. Its contribution exceeded 20% in 92 cities located in developed and emerging economies.
  • The ten highest NO2 contributions were estimated for eight cities in China (37 to 48% of pediatric asthma incidence) followed by Moscow, Russia and Seoul, South Korea, both at 40%.
  • In the US, the top-five most affected cities (as judged by percentage of pediatric asthma cases linked to polluted air) are Los Angeles, New York, Chicago, Las Vegas, and Milwaukee
  • China had the largest national health burden associated with air pollution at 760,000 cases of asthma per year, followed by India at 350,000, and the United States at 240,000.
  • In general, cities with high NO2 concentrations also had high levels of greenhouse gas emissions.

The World Health Organization (WHO) has set Air Quality Guidelines for NO2 and other air pollutants. For NO2, that guideline pins about 21 parts per billion for annual average levels as being safe. The researchers estimate that most children live in areas that conform to this guideline, but say that 92% of new pediatric asthma cases attributable to NO2 sprung up in areas that met the WHO guidelines.

“That finding suggests that the WHO guideline for NO2 may need to be re-evaluated to make sure it is sufficiently protective of children’s health,” said Pattanun Achakulwisut, PhD, lead author of the paper and a postdoctoral scientist at Milken Institute SPH.

The team, however, is confident that we can do better. Many of the solutions aimed at scrubbing cities of the greenhouse gases in their air would also reduce NO2 levels, thus helping prevent new cases of asthma.

The paper “Global, national, and urban burdens of paediatric asthma incidence attributable to ambient NO2 pollution: estimates from global datasets” has been published in The Lancet Planetary Health journal.

Pee, Poop, and Perspiration Will Be Useful in Traveling to Mars

People have effectively been able to acquire fuel and, consequently, energy from human urine. This capability has been known for a number of years. In late 2012, a small group of teenage girls from Nigeria made the news by presenting a generator that ran on urine at the Maker Faire Africa. In their generator, the pee is poured into an electrolytic cell where the hydrogen is isolated from other components in the liquid.

The hydrogen is then purified by passing through a filter. From there, it’s sent to a gas cylinder from which it is further pumped into a cylinder containing liquid borax. The borax aids in separating the hydrogen gas from any remaining moisture. The final step is for this gas to be sent to the generator. The girls’ machine was able to supply six hours’ worth of electricity by using a mere liter of liquid waste.

Of course, this was a rather simple apparatus primarily for display, but the important thing is it worked! Urine’s use for producing gas and/or syngas (synthesis gas) has the potential to be quite revolutionary.

Waste as a Water Source in Space


Credit: Wikimedia Commons.

Recycling everything possible in extraterrestrial day-to-day life and travel saves both space and money. For a while now, astronauts on the International Space Station have been recycling their own perspiration and pee. The purified output is clean water, which is drunk a second time over. This cycle can be repeated over and over.

You’ve heard of twice-baked potatoes? Well, twice-expelled waste is starting to catch up in its popularity. Human urine and condensate (including breath moisture, human sweat, shower runoff, and animal pee) are all distilled and reverted to clean drinking water. As of 2015, about 6,000 extra liters of water are recycled each year.

Waste Empowering Yeast

One of the molecules which makes up our urine is called urea. Furthermore, urea is composed of nitrogen and carbon. Both of these chemicals are needed to feed a yeast, Yarrowia lipolytica, which when genetically tweaked properly can take a variety of forms such as bioplastics and even fatty acids. One particular fatty acid necessary for human health and functionality is Omega-3. The brain requires this nutrient.

Thus, Yarrowia lipolytica is being tested to hopefully be able to produce Omega-3’s efficiently in the future. This would be a great aid to humanity in the occasion of a manned mission to Mars or elsewhere. In addition, future astronauts will use 3D printers onboard their spacecraft to generate tools and other needed objects made of plastic. Yet again, the yeast can be altered to produce a certain type of polyester which could be employed for this purpose.

Feces and Urine for Future Food

The sheer quantity of food needed to sustain a manned mission to Mars remains a big problem. However, a clever party of researchers from Pennsylvania State University believes to have found an efficiently ingenious answer. The concept was discussed in a paper published in late 2017. Their space-saving device, a bioreactor, uses the urine as well as the feces of astronauts to feed a non-harmful bacteria that, in turn, is capable of sustaining the human space travelers.

Within the bioreactor, the solid and liquid waste become condensed leaving salts and methane gas in its place. It’s the methane which is used to grow the microbial mush, an edible element with a texture similar to that of Vegemite, a thick Australian spread made up of leftover brewers’ yeast extract along with an assortment of additives.

As you have seen, our astronauts’ waste will not be wasted. Scientists will surely engineer more ways for bodily waste to be put to beneficial use.

Modern nitrogen-cycle’s birth identified during the Great Oxidation

A new paper sheds light on how life and surface chemistry have evolved alongside each other in Earth’s history. The study analyzed geochemical records of the Great Oxidation 2.3 billion years ago to see how the nitrogen cycle reacted to this major event.

Image credits NASA Goddard Space Flight Center / Flickr.

Some 2.3 billion years ago, Earth was going through spectacular changes. This period, named the Great Oxidation Event, saw the first build-up of biological oxygen in the atmosphere and would forever change life on the planet. But there are still a lot of questions about what happened during this time and why.

Mapping the past

A new study from the University of St Andrews led by Dr. Aubrey Zerkle of the School of Earth & Environmental Sciences comes to answer some of these questions. The paper fills in a roughly 400 million year gap in our understanding of the chemical changes taking place at the time, and how these changes impacted life on Earth.

“The ‘Great Oxidation Event’ was arguably the most dramatic environmental change in Earth history. It was critical to the development of the hospitable environment that we inhabit today, as it was a prerequisite for the evolution of animals that universally require O2 to live,” the researchers explain.

Dr. Zerkle’s team analyzed rock cores at the National Core Library in Donkerhoek, South Africa, which have been used to date the occurrence of the event. They focused on nitrogen, one of the key elements in biochemistry. It’s present in everything from DNA, RNA to amino acids and proteins, therefore controlling global primary productivity — in other words, nitrogen is the hard cap on how fast, and to what extent, the biosphere can develop.

That’s why we make fertilizer out of it.

Despite its importance, large parts of the nitrogen cycle’s response to events in the Earth’s history remain undocumented — including the Great Oxidation. The team created unique high-resolution records of nitrogen isotopes in sedimentary rocks during this period, documenting the birth of the modern nitrate(NO3)-based ecosystems and correlating it with the first evidence of oxygen in the atmosphere.

“Our data shows the first occurrence of widespread nitrate, which could have stimulated the rapid diversification of complex organisms, hot on the heels of global oxygenation,” they add.

Something’s nit-rite here

Despite being the most abundant free element in the atmosphere today, most organisms can’t fix nitrogen gas as-is — they need to assimilate it as nitrites or ammonia. Animals get all their nitrogen by eating other organisms. Plants, which are the main producers in ecosystems, usually rely on symbiotic bacteria cultures around their roots or artificial fertilizers for their nitrogen supply.

The modern nitrogen cycle has a few producers and a lot of re-use.

But you can’t have nitrates without having free oxygen in the environment. As such, oxygen injection into the atmosphere offered not only a source of energy but also the prime materials needed for complex life to evolve.

This only deepens the mystery of the Great Oxidation — we still don’t know why, with the stage all set for it, complex life took so much time to make an entrance.

“The building blocks were apparently in place, the question that remains is why eukaryotic evolution was seemingly stalled for another billion or more years.”

The paper offers insight into how the biosphere of old reacted to drastic environmental changes, a theme which is sadly very relevant today. Knowing how life adapted to these changes in the past may help us predict the future more accurately. At the same time, understanding the workings between the biosphere and geochemistry at home can guide our search for life alien planets.

The full paper “Onset of the aerobic nitrogen cycle during the Great Oxidation Event” has been published in the journal Nature.

Farmers will have to more carefully manage nitrogen fertilization as the world climate warms up to prevent crop loss.

Rising atmospheric CO2 lowers nutrient content in crops

Farmers will have to more carefully manage nitrogen fertilization as the world climate warms up to prevent crop loss.

Farmers will have to more carefully manage nitrogen fertilization as the world climate warms up to prevent crop loss.

Trying to understand the overall effect of climate change on our food supply can be difficult. Increases in temperature and carbon dioxide (CO2) can be beneficial for some crops in some places, but overall changing climate patterns lead to frequent droughts and floods that put a severe strain on yields. It’s not all about production, however. Researchers at  University of California, Davis found that rising CO2 levels are inhibits plants’ ability to assimilate nitrates into nutrients, altering their quality for the worse. Our whole food chain relies on the proteins found in plants, whose energy we assimilate directly or from animals that eat the same plants. Consequently, crop quality in the face of global warming is an aspect that needs to be thoughtfully addressed.

“Food quality is declining under the rising levels of atmospheric carbon dioxide that we are experiencing,” said the study’s lead author Arnold Bloom. “Several explanations for this decline have been put forward, but this is the first study to demonstrate that elevated carbon dioxide inhibits the conversion of nitrate into protein in a field-grown crop.”

Nitrogen and CO2

Food crops use nitrogen to produce the proteins that are vital for human nutrition. Nitrogen is the mineral element that plants and other living organisms require in the greatest quantity to survive and grow. Plants obtain most of their nitrogen from the soil and, in the moderate climates of the United States, absorb most of it through their roots in the form of nitrate. In plant tissues, those compounds are assimilated into organic nitrogen compounds, which have a major influence on the plant’s growth and productivity.

[ALSO READ] We’re not growing enough food to feed the world of 2050

Previously, scientists proved that nitrates assimilation is inhibited by carbon dioxide in the leaves of grain and non-legume plants, however the present study marks the first time that this relation was investigated in field-grown crops.

Samples of wheat that had been grown in 1996 and 1997 at the Maricopa Agricultural Center in Arizona were analyzed by the UC Davis researchers. At that time, carbon dioxide-enriched air was released in the fields, creating an elevated level of atmospheric carbon at the test plots, similar to what is now expected to be present in the next few decades. Almost two decades later, the UC Davis researchers returned to these samples and subjected them to chemical analysis that was not available at the time of harvesting.

[RELATED] Climate change causes lower crop yields than previously thought

Three different measures of nitrate assimilation confirmed that the elevated level of atmospheric carbon dioxide had inhibited nitrate assimilation into protein in the field-grown wheat. It’s safe to assume that other food crops like barley, rice, and potatoes may be subjected to the same risks, though the same experiment needs to be repeated for each of these.

“These field results are consistent with findings from previous laboratory studies, which showed that there are several physiological mechanisms responsible for carbon dioxide’s inhibition of nitrate assimilation in leaves,” Bloom said.

Historical records have documented that the concentration of carbon dioxide in Earth’s atmosphere has increased by 39 percent since 1800. If current projections hold true, the concentration will increase by an additional 40 to 140 percent by the end of the century.

Extrapolating, the researchers found that, in all, global food proteins available for human consumption could drop by as much as 3% in the coming decades as a result of rising carbon dioxide levels. While heavy nitrogen fertilization could partially compensate for this decline in food quality, it would also have negative consequences including higher costs, more nitrate leaching into groundwater, and increased emissions of the greenhouse gas nitrous oxide.

The findings were reported in the journal Nature Climate Change.


drosera carnivorous plant

Carnivorous plants turn to veggie diet due to pollution

Carnivorous plants may soon have to give up their meaty habits and turn veggie, as a recent study found that carnivours plants in Swedish bogs have significantly reduced their preying behavior, due to nitrogen pollution.

drosera carnivorous plantThe  sundew drosera rotundifolia is one of the most common carnivours plant species, growing across much of Northern Europe in rain-fed bogs. Typically, their habitat has low-nitrogen intake which forces them to seek such nutrients elsewhere; evolution, thus, took them on a path where they developed the necessary means and measures to trap and devour insects.

Human induced nitrogen pollution, however, due to fossil fuel burning from plants and vehicles have caused  increased levels of nitrogen deposited by rainfall over these bogs. The carnivorous plants now have access to a lot more nitrogen than they used to need to survive, dwindling their appetite, but at the same time destabilizing the local ecosystem.

“If there’s plenty of nitrogen available to their roots, they don’t need to eat as much,” explains Dr. Jonathan Millett from Loughborough University, the report’s lead author.

Now, these plants absorb more nitrogen through their roots.  Plants in lightly-polluted areas got 57 per cent of their nitrogen from insects; in areas that receive more nitrogen deposition, that figure fell as low as 22 per cent. These figures were reached after scientists analyzed the nitrogen isotope composition in plants; different forms of nitrogen differing by atomic mass. Nitrogen isotopes come in a different mix whether of biological origin, say insects, or from rain deposits.

It’s been found that the carnivorous plants’ leaves are now less sticky, their main weapon for trapping insects, and have also suffered a transformation in colouring, from a red tint, which attracted bugs, to a more greenish hue.

That might no seem like much, but one needs to consider that in an ecosystem, everything is about niches. Each species takes up a free niche, and evolves in that particular direction. Carnivorous plants sped a high amount of energy an specialized elements, and  once a species has gone down this path, it finds it hard to compete with non-carnivorous rivals outside its favoured nitrogen-poor setting.

“In the sites with more nitrogen deposition, these plants now get much more of their nitrogen from their roots, but they still have to bear the residual costs of being carnivorous, and other plants without these will be better able to survive,” Millett comments. “So it’s quite likely we’ll see less abundance and perhaps local extinctions from carnivorous species. The individual plants get bigger and fitter, but the species as a whole is less well adapted to high-nitrogen environments and will lose out over time.”

A similar study is planed for hobs in the UK, where scientists expect to find more startling ratios, because of the more extensive fossil fuel ussage. Low-pollution Swedish bogs showed deposition rates of around 1.8kg of nitrogen per hectare per year; many UK sites are closer to 30kg.

The study was published in the journal New Phytologist.

image credit

Ants use bacteria to grow gardens

leafAnts are most amazing creatures, and there’s so much we could learn from them I wouldn’t even know where to start. As it is, we’ve just started to scratch the surface of what we know about ants, and strangely enouch, researchers are discovering more and more things human and ant societies have in common.

Leaf cutter ants are one of the most remarkable ant species, and scientists have recently found a new quality (or ‘skill’, if you wish) to add to their inventory: they use nitrogen-fixing bacteria to make their gardens grow. You know who else does something similar? Humans.

The finding was reported on 20 November in Science by bacteriologist Cameron Currie from the University of Wisconsin-Madison and analyzes a previously unknown very interesting symbiosis between ants and bacteria, providing a totally new insight on leaf cutter ants and how they managed to be the dominant ant species in the American tropics and subtropics.

“Nitrogen is a limiting resource,” says Garret Suen, a UW-Madison postdoctoral fellow and a co-author of the new study. “If you don’t have it, you can’t survive.”

Indeed, this ‘business relationship’ allows the ants to be impressively successful, while the bacteria thrives too.

“This is the first indication of bacterial garden symbionts in the fungus-growing ant system,” says Currie, a UW-Madison professor of bacteriology.


The fungus growing ants are technically herbivores, but without the bacteria, there is absolutely no way they could get the necessary nutrients.

“Without nitrogen, there is no way these guys could achieve such large colony sizes. These ants are one of the most dominant insects in the Neotropics. The ability to have colonies with millions of ants is predicted to require a tremendous amount of nitrogen.”

So how do they do it ? The gardens in question are initially sowed by the ants, which bring leaf pieces into their underground nests. From the leaf, a fungus called Leucoagaricus gongylophorus starts growing – which was traditionally viewed as the ants’ food, ever since 1890s research; only recently did researchers start taking into consideration the more complex interactions between the fungus, the bacteria and ants.

But things get even more complicated from here on – genetic analysis of proteins found in bacteria revealed even more complex interactions.

“Our results show that calling these ‘fungal gardens’ is pretty misleading; ‘fungus-bacterial communities’ would be far more accurate,” said Kristin Burnum, a bioanalytical chemist at the Department of Energy’s Pacific Northwest National Laboratory. . “Bacteria are not only integral residents of these communities, but they perform essential tasks that keep the communities — and the ants that help cultivate them — living.”


Researchers hope that understanding how this (sort of) symbiosis works can not only boost our understanding of complex ant societies and biological mechanism, but also lead to more effective development of biofuels.

Healthy Rivers Needed To Remove Nitrogen

healthy riverNature has its own way of protecting itself, and we should have already learned this (the hard way), because so many catastrophes have happened as a result of man’s destructive work. Look at the damage caused by the recent tsunamis; they would have been almost neglectable if we hadn’t destroyed the plankton, which has a very protective action. Also, despite the numerous experiements and studies, we have yet to find a solution to this issue.

The case of cleaning nitrogen caused by human activities seems to be similar in many ways, as scientists haven’t come up with a viable plan of cleaning it yet, except for an easy, natural way: maintaining healthy river systems. That’s right, healthy river streams with vibrant ecosystems play a critical role in removing excess nitrogen caused by human activities, according to a recent major study published in nature.

The study was led by a team of 31 aquatic scientists across the United States and it was the first to explain how much nitrogen that rivers and streams can filter through tiny organisms or release into the atmosphere through a process called denitrification.

“The study clearly points out the importance of maintaining healthy river systems and native riparian areas,” said Stan Gregory, a stream ecologist in the Department of Fisheries and Wildlife at Oregon State University, an a co-author of the study. “It also demonstrates the importance of retaining complex stream channels that give organisms the time to filter out nitrogen instead of releasing it downstream.”

The study was conducted after analyzing 72 streams across the United States and Puerto Rico that spanned a diversity of land types, including urban, rural, agricultural and forests. They found out that if the river was healthy, it cleansed roughly 40 to 60 percent of nitrogen within 500 meters of the source. This happens because small organisms, such as algae, fungi and bacteria that may live on rocks, pieces of wood, leaves or streambeds can absorb the nitrogen.

“Streams are amazingly active places, though we don’t always see the activity,” said Sherri Johnson, a research ecologist with the U.S. Forest Service, and a courtesy professor of fisheries and wildlife at OSU.. “When you have a healthy riparian zone, with lots of native plants and a natural channel, the stream has more of an opportunity to absorb the nitrogen we put into the system instead of sending it downriver.”

Global Nitrogen Budget affected by fish



Nature has its own balance which is both sturdy and fragile at the same time; when that balance is broken (by man, what else?) it is very hard and sometimes almost impossible to set things right. That’s why we have to pay attention to the numerous fragile ecosystems because everything is connected.

It goes the same for nutrient cycles that influence the natural world; they are regulated by inputs and outputs. Overlooking this and abusing the “system” may bring short term benefits, but in the long run, we just lose.

Recent research by the Université de Montréal (Canada) and the Cary Institute of Ecosystem Studies (Millbrook, New York) has revealed an important, but seldom accounted for, withdrawal in the global nitrogen cycle: commercial fisheries.

According to this study, the importance of these fisheries has been greatly underestimated. Nitrogen is the most common gas in our atmosphere and it is very important for plants and animals alike. However, having too much of it is not desirable. During the past century, a range of human activities have increased nitrogen inputs to coastal waters.

Fish accumulate nitrogen as biomass and humans eat fish, some of the nitrogen is “given” back to the land. In the 1960s, nitrogen removal in fish harvest was equivalent to 60% of the nitrogen fertilizer delivered to coastal ecosystems throughout the world. Now it has dropped to about 20%. This is very bad news because coastal ecosystems throughout the world are becoming more and more rich in nitrogen resulting in increased phytoplankton blooms, anoxic bottom waters, and coastal dead zones.