stressed

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 Gulf Of Mexico Dead Zone | Earth Wise

July 19, 2021 By EarthWise Leave a Comment

Every summer, a so-called dead zone forms in the Gulf of Mexico. It is primarily caused by excess nutrient pollution from human activities in urban and agricultural areas throughout the Mississippi River watershed.

When these excess nutrients reach the Gulf, they stimulate excess growth of algae, which eventually die and decompose, depleting oxygen as they sink to the bottom. These low oxygen levels near the Gulf bottom cannot support most marine life. Animals that are sufficiently mobile – such as fish, shrimp, and crabs – generally swim out of the area. Those that can’t move away are stressed or killed by the low oxygen.

A team of scientists funded by the National Oceanic and Atmospheric Administration issues an annual forecast for the dead zone based upon a suite of models that incorporate river flow and nutrient data.

The 2021 forecasted area is somewhat smaller than, but close to, the five-year measured average for the dead zone, which is 5,400 square miles, roughly the size of the state of Connecticut. Each year, these forecasts are reported as comparisons to long-term averages, but the problem is that the long-term average is unacceptable.

The Interagency Mississippi River and Gulf of Mexico Hypoxia Task Force has set a goal of reducing the size of the dead zone to a five-year average of 1,900 square miles – about a third of the current average.

Large reductions in nutrient loads have been called for in federal and state action plans for nearly 20 years, but clearly these reductions have not yet been sufficient. The Interagency Task Force continues to provide information for managing nutrient loads in the Mississippi River Basin.

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Average-sized ‘dead zone’ forecast for Gulf of Mexico

Photo, posted October 6, 2020, courtesy of Christine Warner via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Dead Zone In The Gulf Of Mexico | Earth Wise

July 6, 2020 By EarthWise Leave a Comment

The Gulf of Mexico has an area of low to no oxygen in the water that can kill fish and other marine life. It is an annual event that is primarily caused by excess nutrient pollution from human activities in urban and agricultural areas throughout the Mississippi River watershed. When these excess nutrients reach the Gulf, they stimulate the overgrowth of algae, which eventually die and decompose, depleting the oxygen in the water as the algae sink to the bottom.

These low oxygen levels near the bottom of the Gulf cannot support most marine life. Some species – among them many fish, shrimp, and crabs – swim out of the area, but animals that can’t swim or move away are stressed or killed by the low oxygen. The dead zone in the Gulf occurs every summer.

A recent forecast for this summer’s dead zone predicts that the area of low or no oxygen will be approximate 6,700 square miles, which is roughly the size of Connecticut and Delaware combined. This is about 1,100 square miles smaller than last year’s dead zone and much less than the record of 8,776 square miles set in 2017. But it is still larger than the long-term average size of 5,387 square miles.

Making comparisons to the long-term average ignores the fact that the long-term average itself is unacceptable. The dead zone not only hurts marine life, but it also harms commercial and recreational fisheries and the communities they support. The actions that have been taken so far to reduce pollution in the Mississippi watershed are clearly not sufficient to drastically reduce the dead zone in the Gulf.

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Large ‘dead zone’ expected for Gulf of Mexico

Photo, posted October 17, 2017, courtesy of NOAA’s National Ocean Service via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Solar-Powered Desalination

October 4, 2019 By EarthWise Leave a Comment

Turning seawater into drinking water is an energy-intensive process and is therefore pretty expensive. Worldwide, one third of people don’t have reliable access to safe drinking water and they are the least able to afford expensive ways to get it. By 2025, half of the world’s population is expected to live in water-stressed areas.

At a newly-constructed facility in Kenya, a nonprofit company called GivePower has built a desalination system that runs on solar power. The system started operating in the coastal area of Kiunga in July 2018 and can create nearly 20,000 gallons of fresh drinking water each day – enough for 25,000 people.

GivePower started in 2013 as a nonprofit branch of SolarCity, the solar-panel company that ultimately merged with Tesla in 2016. However, GivePower spun off as a separate enterprise shortly before that.

GivePower mostly focuses on building solar-energy systems to provide electricity across the developing world.

Desalination technology is not new, but it is notoriously energy-intensive because it requires high-power pumps. The GivePower system is integrated with a solar microgrid that makes use of Tesla batteries to store energy for when the sun is not shining.

Local residents pay about a quarter of one cent for every quart of water from the system. The Kiunga community has faced ongoing drought and before the GivePower system was installed, was forced to drink from salt water wells, which present serious health risks.

The GivePower system cost $500,000 to build and is expected to generate $100,000 a year, to be eventually used to fund similar facilities in other places.

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A solar-powered system can turn salt water into fresh drinking water for 25,000 people per day. It could help address the world’s looming water crisis.

Photo courtesy of GivePower.

Earth Wise is a production of WAMC Northeast Public Radio.