noise

Plants Make Sounds | Earth Wise

May 9, 2023 By EarthWise Leave a Comment

Some people talk to their plants. It is highly unlikely that the plants are listening, but recent research has found that plants are doing quite a bit of talking of their own.

It turns out that plant emit a variety of click-like sounds, especially when they are stressed in some way, such as being dehydrated or injured. The sounds are actually fairly loud – comparable to the volume of human speech – but occur at frequencies well above the range of human hearing.

The study at Tel Aviv University in Israel monitored plants in a greenhouse that were subjected to various stresses over time. Unstressed plants emitted less than one sound per hour, on average, while stressed plants emitted dozens of sounds every hour.

Recordings of the plant sounds were analyzed by specially developed artificial intelligence algorithms. The algorithms learned how to distinguish between different plants and different types of sounds. Eventually, they could identify the plant and determine the type and level of stress from the recordings. They could even do this in a greenhouse with a great deal of background noise.

The study resolved a very old scientific controversy about whether plants emit sounds. Not only do they, but the sounds contain useful information. We don’t yet know what the mechanism is for plant sounds. It is likely that in nature, the sounds are detected by various animals and perhaps even plants that can detect the high frequencies. And perhaps they react to them as part of seeking food, shelter, or other services that plants provide. Given the right tools, we humans may also be able to make use of the sounds being made by plants.

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Plants Emit Sounds – Especially When Stressed

Photo, posted February 20, 2009, courtesy of ProBuild Garden Center via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The Importance Of City Trees | Earth Wise

January 28, 2022 By EarthWise Leave a Comment

It is well known that green spaces can improve the quality of life and create a better climate in cities. City trees and vegetation can help reduce urban heat island effects by shading buildings and roads, deflecting radiation from the sun, and releasing moisture into the atmosphere. City trees and green spaces have also been proven to increase property values, promote wildlife and plant diversity, reduce noise pollution, and improve human health. But how important are trees and vegetation for producing cleaner air in cities?

According to a new study led by researchers at the University of Gothenburg in Sweden, trees do contribute to cleaner air in cities, but the degree to which they do so varies greatly between different locations.

The research team measured air pollutants across seven urban settings in the city of Gothenburg, and compared them with pollutants on the leaves of deciduous trees. The researchers chose to focus on polycyclic aromatic hydrocarbons (PAHs), which are pollutants generated primarily during the incomplete combustion of organic materials, like coal, oil, and wood.

The results revealed that the pollutants in leaves did increase over time. The researchers were able to show a clear correlation between the level of air pollutants and the concentration of pollutants in leaves.

But at the same time, the researchers discovered that pollution levels varied greatly between measurement sites. For example, the levels of PAHs were seven times higher at the most polluted site (the city’s main bus station) than they were at a location on the periphery of the city.

The research team hopes its findings will be used to help guide the planning of future urban landscapes.

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Trees are important for cleaner air in cities

Photo, posted November 5, 2021, courtesy of Maria Eklind via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Roads And Chimpanzees | Earth Wise

November 8, 2021 By EarthWise Leave a Comment

The chimpanzee is a species of great ape native to tropical regions of Central and West Africa. Chimpanzees are highly social animals and can live to be over 50 years old. In fact, chimpanzees are our closest cousins. We share about 98% of our genes with chimpanzees.

According to the African Wildlife Federation, it’s estimated that at most only 300,000 chimpanzees remain in the wild today. They face a myriad of challenges, including habitat degradation and hunting.

According to new research from the University of Exeter in the U.K., roads have a negative impact on chimpanzee populations that can extend for several miles. In the study, which was recently published in the journal Conservation Letters, the researchers analyzed the impact of major and minor roads on wild western chimpanzee numbers in the eight African countries in which they live. They found that negative impacts extended an average of 10.7 miles from major roads, and 3.4 miles from minor roads. The researchers found that the density of chimpanzee populations dropped steadily from the edges of these areas to the lowest value alongside the roads. Only 4.3% of the chimpanzees’ range remains unaffected by roads.

While the study did not investigate why roads affect chimpanzee numbers, the research team did offer some clues. In addition to noise and roadkill, roads provide access to unexploited areas for industries that often reduce or remove chimpanzee habitats. Roads can also restrict chimpanzee movements, and provide easier access for hunters.

The researchers hope their findings will bring about more effective guidelines to mitigate the impact of roads on wildlife.

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Roads have far-reaching impact on chimpanzees

Photo, posted August 12, 2014, courtesy of Rod Waddington via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Importance Of Urban Green Spaces | Earth Wise

August 10, 2021 By EarthWise Leave a Comment

Projections are that 68% of the global population will be living in cities by 2050. It is therefore not surprising that urban green spaces are critically important for promoting mental and physical well-being.

An international study, published in Science Advances, took soil samples from different types of urban green spaces and comparable neighboring natural ecosystems in 56 cities from 17 countries across six continents.

The study concluded that even roadside plantings contribute a range of important microbial communities that are critical for sustaining productive ecosystems services, such as filtering pollutants and sequestering carbon dioxide.

Parks and gardens constitute most of the open spaces available for recreational activities in cities and play important roles in curbing pollution, reducing noise, and lowering air temperatures.

In addition, human exposure to soil microbes has been shown to be beneficial to human health by promoting effective immunoregulation functions and reducing allergies. The study found that city parks and even roadside plantings support a great variety of different microbes that are different from natural ecosystems.

We think of roadsides as being barren but the vegetation along footpaths and roadsides are important microbial habitats. Some European cities, such as Bern in Switzerland, have instituted policies to protect the natural vegetation along footpaths and roadsides.

The new study is a part of a series of research efforts looking at the important of green spaces for ecosystem health. As the world becomes increasingly urbanized, every bit of greenery in cities and highways is important and is needed for sustaining a healthy environment.

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Every spot of urban green space counts

Photo, posted June 3, 2013, courtesy of Manuel MV via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Oil Platforms And Biodiversity | Earth Wise

April 8, 2021 By EarthWise Leave a Comment

We have previously reported on the important role that offshore oil platforms seem to play for fish. In short, the support structures of offshore oil platforms that often rise hundreds of feet through the water column create essentially a prefabricated reef for marine life.

According to a new study recently published in the British journal Ecological Solutions and Evidence, the large gatherings of fish around oil and gas platforms attract harbour porpoises searching for food – despite the fact that noise from industrial activities normally scares porpoises away.

Harbour porpoises are one of the smallest whale species and the only whale species that’s known to breed in Danish waters. The species has been protected in Danish waters since 1967. Previous studies have demonstrated that underwater noises from sources like shipping and industry typically scare porpoises away.

But according to new research from scientists at Aarhus University in Denmark, there are actually more porpoises around the largest Danish oil platform – Dan F – in the North Sea than there are within the three to ten kilometers surrounding the platform. The research team found that the platform acts as a natural reef where porpoises can find favorable habitat and food.

Currently, the international OSPAR convention requires that all decommissioned oil and gas platforms be removed from the ocean. But according to researchers, leaving the old platforms in the ocean to serve as artificial reefs is actually more beneficial to the marine environment.

In the Gulf of Mexico, the United States program Rigs to Reefs has converted 558 oil and gas platforms into artificial reefs.

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Harbor porpoises attracted to oil platforms when searching for food

Photo, posted March 26, 2008, courtesy of Dave Herholz via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Improved Radar For Cars | Earth Wise

December 31, 2020 By EarthWise Leave a Comment

Self-driving cars require a variety of sensor systems in order for the cars to safely navigate roads and deal with the wide range of objects and conditions that they encounter. Two competing technologies that cars use to identify and locate objects on the scene are radar and LiDAR.

Radar uses transmitted radio waves to locate objects and LiDAR bounces laser beams off of objects. Each has its shortcomings. Radar has the problem that only a small fraction of the transmitted signals gets reflected back to the sensor, so that there is frequently insufficient data to fully characterize a scene. LiDAR has the problem that it is an optical system that does not work well in fog, dust, rain, or snow. It is also much more expensive than radar.

Researchers at the University of California San Diego have developed a new system that they describe as a LiDAR-like radar. The system consists of two radar sensors placed on a car’s hood and spaced about 1.5 meters apart. This configuration enables the system to see more space and detail than a single radar sensor.

Having two radars at different vantage points with an overlapping field of view creates a region of high-resolution with a high probability of detecting the objects that are present. The system also overcomes noise problems of conventional radar systems.

The researchers developed new algorithms that can fuse the information from two different radar sensors and produce a new image free of noise.

Self-driving cars have to combine detection technologies like radar with cameras and ultrasonic sensors. Duplicating the capabilities that people use in order to safely drive a car is a complex problem requiring a combination of multiple sensors and sophisticated software.

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Upgraded radar can enable self-driving cars to see clearly no matter the weather

Photo, posted January 2, 2014, courtesy of Bradley Gordon via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Quiet In The Pandemic | Earth Wise

November 19, 2020 By EarthWise Leave a Comment

The early months of the Covid-19 pandemic had dramatic effects on many aspects of our daily lives. Vehicle traffic, air pollution, and many other aspects of modern life saw reduced levels not seen in decades. It turns out that one of the things that saw reduced levels was people’s exposure to environmental noise.

According to University of Michigan researchers, daily average sound levels dropped in half during the time that local governments made announcements about social distancing and issued stay-at-home orders in March and April as compared to noise levels measured in January and February.

The data was acquired from the Apple Hearing Study, which looked at noise exposure data from volunteer Apple Watch users in Florida, New York, California, and Texas. The analysis included more than half a million daily noise levels measured before and during the pandemic shutdown.

The noise reduction – 3 decibels, which is a factor of two in noise level – is considered to be quite large and could have a significant effect on people’s overall health outcomes over time.

The four states studied had differing responses in terms of stay-at-home orders. Both California and New York both had really drastic reductions in sound that happened very quickly, whereas Florida and Texas had somewhat less of a reduction.

The study demonstrated the utility of everyday use of digital devices in evaluating daily behaviors and exposures. This sort of analysis could allow researchers to begin describing what personal sound exposures are like for Americans who live in a certain state, or are of a certain age, or who do or don’t have hearing loss. The Apple Hearing Study is continuing and is still accepting new participants.

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Stay-at-home orders cut noise exposure nearly in half

Photo, posted April 10, 2020, courtesy of Joey Zanotti via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Earth Itself Is Quieter | Earth Wise

May 15, 2020 By EarthWise Leave a Comment

Our stories often discuss how human activities change the natural environment. With most of us confined to our homes, the lack of human activities is having profound effects on the environment. We are talking about some of these this week.

With about a third of the world’s population sheltering in place, our planet is much quieter these days. It isn’t just our machines, vehicles, and factories that are making less noise. The earth itself is quieter. There has been a reduction in the earth’s seismic vibrations.

According to the journal Nature, various human-powered movements contribute to the persistent vibration of the earth’s crust. Things like engines firing up in factories, trains pulling into stations, and trucks barreling down highways all make contributions to seismic activity. Taken individually, such things are insignificant, but taken together, they produce a background of seismic noise that makes it difficult for seismologists to detect natural signals such as volcanic activity and earthquake aftershocks.

With much human activity on pause during the coronavirus outbreak, seismologists across the globe are seeing significant reductions in background seismic noise levels.

This respite in seismic noise, for as long as it lasts, represents an opportunity for scientists to better study the natural activity in the earth’s crust. Researchers studying the impact of ocean waves to predict volcanic activity and those who triangulate the location of earthquake epicenters may be able to make more sensitive measurements than under normal conditions.

There are very few positive things one can say about the coronavirus crisis, but it is providing opportunities to study and observe aspects of the natural world that are ordinarily drowned out by the bustle of humanity.

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Coronavirus lockdowns across the globe are actually causing the Earth to move less

Photo, posted March 9, 2020, courtesy of Jeremy Segrottvia Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Should New York Build A Storm Surge Barrier?

December 6, 2019 By EarthWise Leave a Comment

In 2012, Superstorm Sandy’s storm surge combined with a high tide and buried lower Manhattan under 13 feet of water. Across all five boroughs, subways, highways, and parking garages flooded and homes and businesses were destroyed. Sandy caused nearly $20 billion in damages in New York City alone and more than 50 people died.

Ever since that disaster took place, there have been discussions about building storm surge barriers to protect the city from future storms. Columbia University’s Sabin Center recently hosted an event to discuss the feasibility of building such barriers.

A study by the U.S. Army Corps of Engineers called the NY and NJ Harbor and Tributaries Focus Area Feasibility Study (HATS, for short) evaluates five options for coastal protection, which range in scope and price.

The most extensive option would involve constructing six miles of storm surge gates along with 26 miles of floodwalls, levees, and buried seawalls. This option would cost $62 billion but could theoretically save $131 billion in damages and protect 95% of the study area.

The study also considers the side effects of building storm surge barriers. These include environmental impacts such as effects on fish and wildlife, water quality, noise and vibrations, and changes in water flow. While these effects can be quite serious and there is opposition from many quarters related to environmental impacts, others point out that there is really no other credible defense against storm surge. The debate over whether or not to build storm surge barriers could easily last for many more years.

In the bigger picture, storm surge barriers do nothing to protect against rain-driven flooding, sea level rise, and tidal floods which continue to increase.

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