PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

Planting some tree species may worsen, not improve, NYC air, says new study

Interactions with manmade pollutants can create ozone

Planting some tree species may worsen, not improve, NYC air, says new study
2024-08-05
(Press-News.org) In line with longstanding initiatives to expand its green spaces, New York City is planting tens of thousands of trees each year. They provide shade, lower surface temperatures by releasing moisture, absorb a surprising amount of airborne carbon, scrub out soot and other floating pollutants, and provide wildlife habitat along with just plain beauty. What could go wrong?

Actually, something could go wrong, according to a new study. Oaks and sweetgums, which currently account for a majority of the city’s trees, produce huge amounts of volatile compounds called isoprenes. Harmless by themselves, isoprenes interact rapidly with polluting nitrogen oxides emitted by vehicles, buildings and industry to form ground-level ozone―a prime factor in many respiratory ailments, especially chronic bronchitis and asthma.

The research, carried out by scientists at the Columbia Climate School’s Lamont-Doherty Earth Observatory and other institutions, found that if the city maintains past species patterns in new plantings, isoprene production in Manhattan in coming decades will go up by about 140%, and resulting summer ozone levels as much as 30%. In Queens, which has the most room of any borough for more trees, isoprene production could quadruple, with corresponding increases in peak ozone; the other boroughs are somewhere in between. The study was just published in the journal Environmental Science & Technology.

“We’re all for planting more trees. They bring so many good things,” said study coauthor Róisín Commane, an atmospheric chemist at Lamont-Doherty. “But if we’re not careful, we could make air quality worse.”

“There is no reason to think that trees don’t play a role in what’s in the air,” said lead author Dandan Wei, who did the research as a postdoctoral scientist at Lamont-Doherty. “We just didn’t have the tools before this to understand this particular aspect.”

The leaves of some tree species emit isoprene as a byproduct of photosynthesis, though no one is quite sure why. With oaks, emissions tend to increase exponentially with heat, at least until air temperatures reach the high 90s. Some scientists think this helps keep leaf tissues from drooping and losing their ability to photosynthesize as it gets hotter. Emissions of these and other volatile compounds by trees may also have something to do with attracting pollinating insects. For whatever reason, oaks and sweetgums are especially prolific; oaks emit some 800 times more isoprene than low emitters like maples or London planes. (Fun fact: the oak-rich Blue Ridge Mountains get their bluish tinge when seen from afar due to vast amounts of isoprene and other volatile compounds reacting indirectly with water to form tiny floating droplets.)

New York City is home to some seven million trees, covering 22% of the surface, according to the city Parks Department, which controls planting and maintenance on public property. Parks and forests contain some five million, of which more than half are oaks of various kinds and sweetgums (37% and 17% respectively). On the streets, (close to 700,000 trees at last count), oaks comprise 18% and sweetgums just a small number. London planes are the most common street trees, comprising a third. Some 130 other species account for the rest.

The authors of the new study carried out their research by analyzing newly available satellite imagery showing the city’s tree canopy in 30-by-30-meter grids, and combining it with 2016 and 2018 Parks Department censuses of tree species. They then fed in data from scientists including study coauthor Andrew Reinmann, an environmental ecologist at the City University of New York Graduate Center, who does lab experiments on tree leaves to measure their isoprene production under different conditions. The researchers scaled up the lab data to the city’s actual tree coverage, and modeled how trees interact with tailpipe and building emissions of nitrogen oxides.

They found that emissions from trees play a controlling role in the formation of ozone on hot summer days, when levels routinely exceed the federal safety levels of 70 parts per billion. Levels sometimes now reach 100 parts per billion; the addition of new trees could eventually drive it up even further, says the study.

But isoprene from trees alone is not to blame. Ozone cannot form without one essential precursor chemical: nitrogen oxides, also known as NOx, emitted during combustion of fossil fuels by vehicles, hot-water boilers, power plants and industry.

“If we lowered NOx significantly, trees wouldn’t be a problem,” said Wei. “We don’t want to convey the idea that trees pollute the air. It’s the cars.”

New York has made some headway at reducing nitrogen oxides in recent years, but the pace has been agonizingly slow. The study says that at current rates of 2% to 5% a year, it would take 30 to 80 years for the city to reduce emissions by a factor of five―the level at which emissions from trees would no long play a role in ozone formation.

No quick fix appears to be imminent. The city’s Local Law 97 mandates that many buildings become carbon neutral, which would largely eliminate fossil fuels―but not until 2050―and electric vehicles are still just dots on the horizon. In June, New York Gov. Kathy Hochul suddenly canceled a plan decades in the making to reduce vehicle traffic by imposing congestion pricing in Manhattan. Prospects for its revival are uncertain.

Meanwhile, the City Council passed a 2023 resolution calling for an increase in tree-canopy coverage from its current 22% to at least 30% by 2035. This would require 250,000 new trees. A 2022 study by The Nature Conservancy found that canopy cover actually could be increased to 42% without impinging on existing landscapes such as buildings and roads.

The Parks Department is cognizant of the issue. A 2020 study carried out by some of its researchers concluded that city trees emit more than 800 tons of volatile compounds each year, including isoprene. “We didn’t make a big deal of that,” said Novem Auyeong, a Parks Department senior scientist who oversees practical research into how the city should manage its natural resources. Like the authors of the new study, she said trees should not be viewed as the enemy. “We could plant any trees we want to, if we just rethink our car-centric lifestyle,” she said.

In any case, the department has already reduced the proportion of oaks it plants in favor of a more diverse mix―but not because of the isoprene question. There was a mass die-off of the city’s American elms in the 20th century, and in the past several years, of ash trees, both due to introduced exotic pests. “We’ve learned our lesson. We’re trying to diversify so if one pest comes along, we have other trees,” said Auyeong.

The department focuses on trees native to the region, including the native oaks that dominate many eastern forests. According to its data, of 55,533 trees planted in the city’s forested areas from to 2018 to 2023, the percentage of oaks was down to 20%. On the streets, 57,335 trees were planted; 17% of them were oaks. In the fiscal year ending this June, some 18,000 more were planted, though the species composition is not yet available.

“We’re not going to go cutting down any big old oaks,” and neither will the department completely stop planting new ones, said Auyeong. “You have to think about what you would lose if you do that.” Oaks are keystone species, she pointed out, providing food and habitat for native insects, birds and mammals. They provide excellent shade, can grow in relatively small spaces, and unlike other desirable shade species such as tulip trees, are relatively unbothered by the city’s stew of air pollution, ozone and otherwise. Importantly, northern red oaks in particular can function in high temperatures when other trees shut down. Up to a point, they may in fact grow even better as the climate gets hotter, according to a 2008 study.

“Oaks are tough trees. They might be able to survive climate change,” said Commane. “There are still wonderful reasons to have them around.”

# # #

Scientist contacts:
Dandan Wei  dandanwei87@gmail.com
Róisín Commane  r.commane@columbia.edu

More information: Kevin Krajick, Senior editor, science news, Columbia Climate School/Lamont-Doherty Earth Observatory kkrajick@climate.columbia.edu 917-361-7766

Lamont-Doherty Earth Observatory develops fundamental knowledge about the origin, evolution and future of the natural world, from the planet’s deepest interior to the outer reaches of its atmosphere, on every continent and in every ocean.
www.ldeo.columbia.edu  |  @LamontEarth

The Columbia Climate School develops innovative education, supports groundbreaking research and fosters essential solutions, from the community to the planetary scale.

 

 

 

END


[Attachments] See images for this press release:
Planting some tree species may worsen, not improve, NYC air, says new study Planting some tree species may worsen, not improve, NYC air, says new study 2 Planting some tree species may worsen, not improve, NYC air, says new study 3

ELSE PRESS RELEASES FROM THIS DATE:

Ben-Gurion University scientist uses state-of-the-art microscopy to discover drug candidates for cancer

2024-08-05
BEER-SHEVA, Israel, August 5, 2024 – Microscopy has been making leaps and bounds in recent years. Science that was inconceivable a few years ago has become a matter of programming state-of-the-art microscopes to process reams of data. Dr. Gabriel Frank quickly realized the potential of cryo-electron microscopy to discover the molecular structures at levels heretofore unobservable. When he joined Ben-Gurion University of the Negev, he pushed for the University to enter the field, culminating in the establishment of the Guzik Center for Advanced Microscopy and the purchase of a new more advanced electron microscope. Using this microscope, Dr. ...

Configuration design method of mega constellation for low earth orbit observation

Configuration design method of mega constellation for low earth orbit observation
2024-08-05
First, satellites in the mega constellation are categorized and the constellation design based on different satellite division is proposed. Satellites in the mega constellation are divided into 2 types, namely, the basic satellites and the accompanying satellites. All basic satellites that are surrounded by accompanying satellites are evenly distributed globally, and they have the same subsatellite trajectory. A basic satellite and its accompanying satellites are defined as a satellite group. The constellation is composed ...

Sometimes it hurts to think

2024-08-05
If somebody complains that it hurts to think, they may be onto something, as mental exertion appears to be associated with unpleasant feelings in many situations, according to research published by the American Psychological Association. “Managers often encourage employees, and teachers often encourage students, to exert mental effort. On the surface, this seems to work well: Employees and students do often opt for mentally challenging activities,” said senior author Erik Bijleveld, PhD, of Radboud University. “From this, you may be tempted to conclude that ...

FAU lands $1.3M NSF grant to boost dryland soil quality amid climate stressors

FAU lands $1.3M NSF grant to boost dryland soil quality amid climate stressors
2024-08-05
Drylands, found across every continent, cover about 45% of the Earth's land surface and support 38% of the human population. In these regions, precipitation is low and evaporation rates are typically high, leading to an arid or semi-arid climate. Due to scarce water resources and sparse vegetation, drylands present formidable challenges for agriculture and human habitation. As the climate continues to warm, drylands are rapidly expanding.  A particularly urgent problem in drylands is climate-driven soil degradation, which affects about 33% of the planet’s land surface. Drylands host ...

Self-powered pump harnesses light and chemistry to target, capture pollutants

Self-powered pump harnesses light and chemistry to target, capture pollutants
2024-08-05
Dartmouth researchers have developed a self-powered pump that uses natural light and chemistry to target and remove specific water pollutants, according to a new report in the journal Science. As water enters the pump, a wavelength of light activates a synthetic molecular receptor designed to bond to negatively charged ions, or anions, a class of pollutants linked to metabolic disruptions in plants and animals. A second wavelength deactivates the receptors as water exits the pump and causes them to release the ...

Heart transplant list doesn’t rank kids by medical need, Stanford Medicine-led study finds

Heart transplant list doesn’t rank kids by medical need, Stanford Medicine-led study finds
2024-08-05
The method used across the United States to wait-list children for heart transplants does not consistently rank the sickest patients first, according to a new study led by Stanford Medicine experts.  The study will publish online Aug. 5 in the Journal of the American College of Cardiology. Adding nuance to the wait-list system by accounting for more health factors could reduce children’s risk of dying while they await donor hearts, according to the study’s authors. A revision to the way donor hearts are assigned is already in process. The study adds evidence for why it is needed, they ...

Advancing towards a novel, highly accurate method for cervical cancer screening

Advancing towards a novel, highly accurate method for cervical cancer screening
2024-08-05
Cervical cancer is a highly prevalent cancer, with approximately 500,000 new cases diagnosed each year. Shockingly, the number of individuals diagnosed with precursor lesions in the cervix—also known as cervical intraepithelial neoplasia (CIN)—is 20 times higher. As with many potentially malignant conditions, early diagnosis of cervical cancer can make all the difference in a patient’s life in terms of treatment outcomes. For this, developing effective, convenient, and easily available screening protocols for CIN and cervical cancer is of paramount importance. Currently, the two ...

First measurement of electron- and muon-neutrino interaction rates at the highest energy ever detected from an artificial source

First measurement of electron- and muon-neutrino interaction rates at the highest energy ever detected from an artificial source
2024-08-05
Neutrinos are fundamental particles in the Standard Model of particle physics, notable for their extremely small masses and weak interactions with matter. They are important for answering fundamental questions about the universe, including why particles have mass and why there is more matter than antimatter. Despite being abundant, their weak interactions make their detection difficult, and hence they are called “ghost particles.” At any given moment, numerous neutrinos freely pass through the Earth and our bodies, which originate from the Sun or cosmic rays. Understanding their rare interactions with matter is crucial for obtaining a more complete picture ...

Breakthrough: Natural bacteria compound offers safe skin lightening

Breakthrough: Natural bacteria compound offers safe skin lightening
2024-08-05
Melanin protects the skin—the body's largest organ and a vital component of the immune system—from the damaging effects of ultraviolet (UV) radiation. When the skin is exposed to UV radiation, melanin production is stimulated in melanocytes, with tyrosinase playing a key role in the biosynthetic pathway. However, disruptions in this pathway caused by UV exposure or aging can lead to excess melanin accumulation, resulting in hyperpigmentation. To address this, tyrosinase inhibitors that suppress melanin synthesis have become valuable in the cosmetic industry. Unfortunately, some of these compounds, ...

Study analyzes potato-pathogen ‘arms race’ after Irish famine

Study analyzes potato-pathogen ‘arms race’ after Irish famine
2024-08-05
In an examination of the genetic material found in historic potato leaves, North Carolina State University researchers reveal more about the tit-for-tat evolutionary changes occurring in both potato plants and the pathogen that caused the 1840s Irish potato famine.  The study used a targeted enrichment sequencing approach to simultaneously examine both the plant’s resistance genes and the pathogen’s effector genes – genes that help it infect hosts – in a first-of-its-kind analysis. “We use small pieces of historic leaves with the pathogen ...

LAST 30 PRESS RELEASES:

Slow editing of protein blueprints leads to cell death

Industrial air pollution triggers ice formation in clouds, reducing cloud cover and boosting snowfall

Emerging alternatives to reduce animal testing show promise

Presenting Evo – a model for decoding and designing genetic sequences

Global plastic waste set to double by 2050, but new study offers blueprint for significant reductions

Industrial snow: Factories trigger local snowfall by freezing clouds

Backyard birds learn from their new neighbors when moving house

New study in Science finds that just four global policies could eliminate more than 90% of plastic waste and 30% of linked carbon emissions by 2050

Breakthrough in capturing 'hot' CO2 from industrial exhaust

New discovery enables gene therapy for muscular dystrophies, other disorders

Anti-anxiety and hallucination-like effects of psychedelics mediated by distinct neural circuits

How do microbiomes influence the study of life?

Plant roots change their growth pattern during ‘puberty’

Study outlines key role of national and EU policy to control emissions from German hydrogen economy

Beloved Disney classics convey an idealized image of fatherhood

Sensitive ceramics for soft robotics

Trends in hospitalizations and liver transplants associated with alcohol-induced liver disease

Spinal cord stimulation vs medical management for chronic back and leg pain

Engineered receptors help the immune system home in on cancer

How conflicting memories of sex and starvation compete to drive behavior

Scientists discover ‘entirely unanticipated’ role of protein netrin1 in spinal cord development

Novel SOURCE study examining development of early COPD in ages 30 to 55

NRL completes development of robotics capable of servicing satellites, enabling resilience for the U.S. space infrastructure

Clinical trial shows positive results for potential treatment to combat a challenging rare disease

New research shows relationship between heart shape and risk of cardiovascular disease

Increase in crisis coverage, but not the number of crisis news events

New study provides first evidence of African children with severe malaria experiencing partial resistance to world’s most powerful malaria drug

Texting abbreviations makes senders seem insincere, study finds

Living microbes discovered in Earth’s driest desert

Artemisinin partial resistance in Ugandan children with complicated malaria

[Press-News.org] Planting some tree species may worsen, not improve, NYC air, says new study
Interactions with manmade pollutants can create ozone