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Harvesting Water From Air | Earth Wise

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Developing new technologies that harvest water from the air is a growing field of research driven by the fact that more and more people live in areas where fresh water is in short supply.  Estimates are that roughly half the world’s population lives in regions with severe freshwater shortages for at least one month each year.

We have previously discussed some of the novel approaches that researchers are taking to enhance water harvesting.  The work at UC Berkeley using metalorganic frameworks is a notable example.

One of the key problems in harvesting water from air is that many droplets that condense from water vapor in the air are too small to be collected and when they cover a surface, they can actually impede further condensation.

University of Texas at Dallas researchers have developed a novel surface that encourages tiny water droplets to move spontaneously into larger droplets.  The droplets actually self-climb along an oil, ramp-shaped meniscus.  The meniscus acts like a bridge along which microdroplets spontaneously climb upward and coalesce with larger water droplets.  They call this the coarsening droplet phenomenon.  It is enabled by a liquid lubricant with a unique hydrophilic nature.  They actually discovered the lubricant’s special properties by accident when in a lubricant test they observed smaller water droplets propel themselves into larger droplets.

Based on experimental data, the coarsening surface enhances the water harvesting rate 200% higher than other techniques.  The team continues to work on ways to use the new lubricant to make sustainable water harvesting systems that are mobile, smaller in size, lower in weight, and less expensive.  If they are successful, they will essentially be able to harvest water anywhere that has air.

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New Physical Phenomenon Aids Harvest of Water from Air

Photo, posted April 26, 2014, courtesy of Toukou Sousui via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Cleaner Water Using Corn | Earth Wise

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Corn is the largest agricultural crop in the U.S., and it is also one of the most wasteful.  About half of the harvest ends up as stover – corn stalks, leaves, husks, and cobs – once the kernels are used for food.

Corn stover has relatively few commercial or industrial uses.  It can be used to produce biofuel, but that is not very energy efficient.  It is sometimes used as a low-quality livestock feed as well.  Mostly, it is just burned if it is used at all.

Researchers at the University of California Riverside have developed an energy-efficient way to make good use of stover by transforming it into activated carbon for use in water treatment.

Activated carbon – often called activated charcoal – is an organic material that is specially treated to contain millions of microscopic pores that make it highly absorbent.  It has many industrial uses, the most common of which is for filtering pollutants out of drinking water.  Most household water filters such as Brita filters as well as the ones built into refrigerators make use of activated carbon.

The Riverside researchers explored methods for producing activated carbon from charred corn stover and found that processing the material with hot compressed water – a process known as hydrothermal carbonization – produced highly absorbent activated carbon with superior properties compared to material produced by slow pyrolysis, where corn stover is charred at increasing temperatures over a long period of time.

According to the researchers, it is important to create approaches that convert waste into high-value materials, fuels, and chemicals in order to create new value streams and eliminate the environmental harm that comes from a so-called “take-make-dispose” economic model.

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Cleaner Water Through Corn

Photo, posted September 15, 2010, courtesy of the United Soybean Board / the Soybean Checkoff via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Potential For Solar Canals In California | Earth Wise

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California’s network of almost 4,000 miles of aqueducts is the world’s largest water conveyance system.  It serves the state’s Central Valley which produces a quarter of America’s food.  About 20% of the nation’s groundwater demand is pumped from Central Valley aquifers.

A recent study by the University of California Santa Cruz and UC Merced has determined that covering these aqueducts with solar panels could be an economically feasible way to advance both renewable energy and water conservation.  California’s aqueducts might more properly be called canals because they are located at ground level.  

The concept of solar canals has been gaining increasing interest around the world as the changing climate leads to more droughts in many regions.  Placing solar panels above the canals can shade them to help prevent water loss through evaporation.  In addition, some types of solar panels can work better situated over canals because the cooler environment improves their operation.  In addition to the increased solar panel output and the water evaporation savings, shade from solar panels could help control the growth of aquatic weeds, which are a costly canal maintenance issue.

Spanning canals with solar panels can be accomplished either by using steel trusses or suspension cables, either of which is more expensive to build than ordinary ground-mounted solar panel supports.  But the research study showed how the benefits of solar canals combine to outweigh the added costs for cable-supported installations.

Apart from the economic benefits of a solar canal system, producing solar energy in the canal system could eliminate the use of 15-20 diesel-powered irrigation pumps, helping to reduce air pollution in a region with some of the nation’s worst air quality.

Solar canals could be a real winner.

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New analysis shows potential for ‘solar canals’ in California

Photo, posted July 23, 2015, courtesy of Lance Cheung / USDA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Rising Seas And Wastewater Leakage | Earth Wise

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Global mean sea level has risen nearly 9 inches since 1880, with over two inches of that over just the last 25 years.  The rising water level is primarily due to two factors:  additional water in the oceans coming from melting glaciers and ice sheets; and the thermal expansion of seawater as it warms.  Climate models estimate that over the course of the century, global sea levels will rise at least a foot even if efforts to reduce greenhouse gas emissions are quite successful and, in the worst case, levels could rise as much as 8 feet.

Faced with this situation, the greatest concerns are, initially, increasing amounts of coastal flooding and erosion and, as things get worse, inundation of coastal regions making many places uninhabitable and creating millions of climate refugees.

Recently, computer modeling studies have focused on an additional imminent problem:  the flooding of coastal wastewater infrastructure, which includes sewer lines and cesspools.

A new study by the University of Hawaii at Manoa is the first to provide direct evidence that tidally driven groundwater inundation of wastewater infrastructure is already occurring in urban Honolulu.  The study shows that higher ocean water levels are leading to wastewater entering storm drains and the coastal ocean.  The result is degradation of coastal water quality and ecological health.

The researchers used chemical tracers to detect groundwater discharge and wastewater present at multiple low-lying areas during spring tides.  During high tides, storm drains become channels for untreated wastewater to flood streets and sidewalks. 

People tend to think of sea-level rise as a future problem, but there are already serious effects going on today that are only going to get worse.

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Sea-level rise drives wastewater leakage to coastal waters

Photo, posted August 23, 2011, courtesy of Eric Tessmer via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Scaling Up Green Hydrogen | Earth Wise

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The global hydrogen market generates about $150 billion dollars a year.  The bulk of the market consists of hydrogen used to produce ammonia, refine oil, and produce methanol.  Advocates for hydrogen foresee a $600 billion a year market based on power and industry uses, mobility and transport uses, chemical feedstocks, and construction.  But the problem with expanding the use of hydrogen is that the vast majority of hydrogen in use today is produced from fossil fuels such as natural gas and coal and producing it creates carbon dioxide emissions.

The great hope of the industry is “green hydrogen”- hydrogen produced either without using fossil fuels at all or by capturing and storing the emissions generated. The most likely approach is electrolysis – using electricity to produce hydrogen from water.

Billions of dollars are being invested by both governments and by large oil companies in a race to scale up electrolysis and make it economically attractive.  According to the Hydrogen Council industry lobby group, at least $300 billion is expected to be invested globally over the next decade aimed at developing the green hydrogen that could one day meet almost a fifth of global energy demand.

Many argue that producing green hydrogen with electrolysis is an extremely inefficient way to utilize renewable energy.  Critics of hydrogen-powered vehicles particularly make this argument.   But industrial applications of hydrogen that currently use large amounts of fossil fuels – such as steel manufacturing – may be places where green hydrogen would make a real dent in global emissions.

The race to clean up hydrogen is definitely on.

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The Race to Scale Up Green Hydrogen to Help Solve Some of the World’s Dirtiest Energy Problems

Photo, posted December 16, 2020, courtesy of Sharon Hahn Darlin via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Saving The Giant Sequoia | Earth Wise

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Giant sequoia trees are some of the most remarkable living things on earth.  They can live up to 3,000 years.  The tallest specimens tower over 300 feet, but it is their girth that really sets them apart.  They are usually 20 feet in diameter, and some are up to 35 feet across at the widest.  The largest tree in the world by volume is the General Sherman tree, which has a volume of 52,508 cubic feet. At 2,100 years old, it weighs 2.7 million pounds and is not only the largest living tree, but also the largest living organism by volume on the planet.

Giant sequoias are incredibly hardy.  To have survived thousands of years, the oldest of these trees have endured hungry animals, diseases, fires, snowstorms, El Niño events, years-long droughts, and the efforts of loggers during the 19th and 20th centuries.

In February, unusually high winds knocked down 15 giant sequoias in Yosemite National Park.  While sequoias are amazingly adapted to their narrow range in California’s Western Sierras, it appears as though climate change is altering their habitat faster than the species can migrate or adapt.  Shorter cold seasons have meant more rain instead of snow, leading to floods and mudslides in the winter.  Fires are more likely with less snowpack.  Hotter, drier summers put sequoias under greater stress.

Forest managers work to preserve existing groves through fire mitigation, supplementary water, and careful stewardship of young trees in existing groves.  If these efforts are successful through the ensuing decades, climate change may be just one more thing the sequoias outlasted.  But at least some conservationists are now considering planting a new generation of sequoias in colder, nearby habitats. 

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To Save Giant Sequoia Trees, Maybe It’s Time to Plant Backups

Photo, posted June 8, 2008, courtesy of Joi Ito via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Solar Cell Greenhouses | Earth Wise

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A recent study at North Carolina State University has shown that it can be feasible to use see-through solar panels in greenhouses to generate electricity.  The idea is to use semi-transparent solar panels on greenhouses that allow some of the light to get in for the plants to grow while making the greenhouses energy neutral or even allowing them to generate more power than they use.

The question is how the semi-transparent solar panels might affect greenhouse crops.  To investigate this issue, researchers grew crops of red leaf lettuce from seed to full maturity under a standard set of growing conditions – temperature, water, fertilizer, and CO2 concentration – but varied the light they get. 

A control group was exposed to the full spectrum of white light while three experimental groups were exposed to light through different types of filters that absorbed the particular wavelengths of light that would be absorbed by different types of semitransparent solar cells.

The researchers paid close attention to characteristics of the lettuce that are important to growers, grocers, and consumers:  general appearance, leaf number, leaf size, and weight.  The results were that the lettuce produced using all three kinds of filtered light was essentially identical to that produced in the control group.    Further research is underway looking at how harvesting various wavelengths of light affects biological processes for lettuces, tomatoes, and other crops.

Getting growers to use solar-powered greenhouses would be very difficult if doing so would result in a loss of productivity.  But given these experimental results, it appears as though the decision will boil down to a simple economic argument about whether the investment in new greenhouse technology would be offset by energy production and its resultant savings.

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Study Finds Plants Would Grow Well in Solar Cell Greenhouses

Photo, posted April 8, 2008, courtesy of Brian Boucheron via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Corn Belt Is Losing Topsoil | Earth Wise

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According to a new study published in the Proceedings of the National Academy of Sciences, more than a third of the farmland in the U.S. Corn Belt has completely lost its carbon-rich topsoil due to erosion.   The affected area is nearly 100 million acres and the amount of carbon loss is nearly 2 million tons.

The study, led by scientists at the University of Massachusetts, Amherst, found that the greatest loss of carbon-rich topsoil was on hilltops and ridgelines.  This indicates that tillage – the repeated plowing of fields – was the primary cause of the erosion because loosened soils move downslope.

The loss of topsoil has reduced corn and soybean yields in the Midwest by 6%, resulting in a loss of nearly $3 billion a year for farmers.  In addition, the loosening of the topsoil increases runoff of sediment and nutrients into nearly waterways, worsening water quality.

Previous studies have shown that no-till farming practices can have a significant impact on reducing erosion.  A study published last November found that if farmers shifted entirely to no-till practices, it would reduce soil erosion from U.S. agricultural fields by more than 70%, as well as significantly reducing nutrient and sediment runoff. 

No-till farming is the practice of planting crops without tilling the soil.  Instead, seeds are planted through the remains of previous crops by planters or drills that cut seed furrows, place the seeds, and close the furrow.  Currently less than 15% of farmland in the upper Mississippi River watershed is farmed with no-till practices. 

Even partial changes in tilling practices could produce positive results for topsoil retention and for waterways.

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One-Third of Farmland in the U.S. Corn Belt Has Lost Its Topsoil

Photo, posted September 15, 2010, courtesy of the United Soybean Board / Soybean Checkoff via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Prickly Pear As A Sustainable Crop | Earth Wise

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The fruits and pads of opuntia, better known as prickly pear cactus, find their way into people’s diets in many arid and semi-arid places around the world.  In Mexico, the pads are known as nopales and are used in a variety of dishes.  The pears themselves are used in jams, salads, and juices.

A five-year study by the University of Nevada Reno College of Agriculture, Biotechnology & Natural Resources investigated the prospects for cactus pear to become a major crop like soybeans and corn and to help provide a biofuel source.

As the climate changes, dry areas are going to get dryer and drought issues will increasingly affect traditional crops.

The study looked at the particular opuntia species called the spineless cactus pear and found that it had the highest fruit production while using up to 80% less water than some traditional crops.  Cactus pear can be used for both human consumption and livestock feed.  As a perennial crop, once the fruit and pads are harvested for food, the remaining biomass can be used for biofuel production.

Corn and sugar cane are the most utilized bioenergy crops right now, but these use three to six times more water than cactus pear.  The cactus pear productivity is on par with corn and sugar cane, but not only do they use a fraction of the water, they also have higher heat tolerance.

Over 40% of land area around the world is classified as semi-arid or arid.  There is enormous potential for planting cactus for carbon sequestration.  If nothing else, it makes great sense to grow cactus pear crops in abandoned areas that are marginal and may not be suitable for other crops.

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Study shows cactus pear as drought-tolerant crop for sustainable fuel and food

Photo, posted April 16, 2020, courtesy of Kevin Dooley via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Collapse of Northern California Kelp Forests | Earth Wise

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For thousands of years, thick canopies of kelp formed an underwater forest spanning the coast of Northern California.  Kelp is the cornerstone of a rich subtidal community, providing food and habitat for all sorts of marine creatures.  But in recent years, a shocking transformation has occurred.  Satellite imagery reveals that the area covered by kelp forests off the coast of Northern California has declined by more than 95%.  Only a few small, isolated patches remain.  

In a new study, researchers at the University of California Santa Cruz found that the kelp forest decline was an abrupt collapse as opposed to a gradual decline. 

According to the study, which was recently published in the journal Communications Biology, kelp forests north of San Francisco were resilient to warming events in the past, like El Niños and marine heatwaves. But the decline of a key sea urchin predator – the sunflower sea star – from sea star wasting disease caused the kelp forests’ resiliency to plummet.  Sea urchins are voracious consumers of kelp.     

But it was a series of events – not just the sea urchins – that combined to decimate the Northern California kelp forest.   A marine heatwave that became known as “the blob” developed in 2014 and moved down the West Coast in 2015.  Around the same time, a strong El Niño event developed and brought warmer water up the coast from the south.  The warming ocean waters combined with the ravenous sea urchin population resulted in the dramatic decline of kelp. 

According to researchers, the prospects for a Northern California kelp forest recovery remain poor unless sea urchin predators return to the ecosystem. 

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The collapse of Northern California kelp forests will be hard to reverse

Photo, posted August 13, 2019, courtesy of Sara Hamilton of OSU College of Science via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Solar Energy And Agriculture | Earth Wise

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According to a new study by Oregon State University researchers, co-developing land for both solar voltaic power and agriculture could provide 20% of total electricity generation in the United States with an investment of less than 1% of the annual U.S. budget.

The concept is known as agrivoltaics – using the same land for both growing crops and generating solar energy.  The proponents of agrivoltaics say that it provides more food, more energy, lower water demand, lower carbon emissions, and more prosperous rural communities.

According to the study, wide-scale installation of agrivoltaic systems could lead to an annual reduction of 330,000 tons of carbon dioxide emission in the U.S. – the equivalent of taking 75,000 cars off the road – and the creation of more than 100,000 jobs in rural communities.  All of this could be achieved with minimal effects on crop yields.

The study finds that an area about the size of Maryland would be needed for agrivoltaics to produce 20% of U.S. electricity generation.  That area of 13,000 square miles constitutes about 1% of current U.S. farmland.

The cost of the solar installations would be $1.1 trillion over 35 years and they would pay for themselves from the electricity generated within 17 years.  Installing the arrays would create the equivalent of 117,000 jobs lasting 20 years.

The researchers are going to install a fully functional solar farm on 5 acres of university owned land to demonstrate to the agricultural community and potential future funders how the study’s findings can be applied in real world agricultural systems.

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Combining solar energy and agriculture to mitigate climate change, assist rural communities

Photo, posted October 11, 2011, courtesy of Michael Coghlan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Superstrong Nanofibers | Earth Wise

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Self-assembly is a ubiquitous process in the natural world that leads to the formation of the DNA double helix, the creation of cell membranes, and to many other structures.   Scientists and engineers have been working to design new molecules that assemble themselves in water for the purpose of making nanostructures for biomedical applications such as drug delivery or tissue engineering.  For the most part, the materials created in this way have been chemically unstable and tended to degrade rapidly, especially when the water is removed.

A team at MIT recently published a paper describing a new class of small molecules they have designed that spontaneously assemble into nanoribbons with unprecedented strength and that retain their structure outside of water.

The material is modeled after a cell membrane.  Its outer part is hydrophilic (it likes to be in water) and its inner part is hydrophobic (it tries to avoid water.)  This configuration drives the self-assembly to create a specific nanostructure and by choosing the appropriate chemicals to form the structures, the result was nanoribbons in the form of long threads that could be dried and handled.  The resultant material in many ways resembles Kevlar.   In particular, the threads could hold 200 times their own weight and have extraordinarily high surface areas.  The fibers are stronger than steel and the high surface-to-mass ratio offers promise for miniaturizing technologies for such applications as pulling heavy-metal contaminants out of water and for use in electronic devices and batteries.

The goal of the research is to tune the internal state of matter to create exceptionally strong molecular nanostructures.  The potential for important new applications is considerable and exciting.

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Researchers construct molecular nanofibers that are stronger than steel

Photo, posted June 19, 2007, courtesy of Andrew Hitchcock via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Can We Tow Icebergs To Use Their Water? | Earth Wise

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At any given time, there are thousands of icebergs adrift in Antarctica that are hundreds or even thousands of feet across.  For at least fifty years, there has been speculation about whether such icebergs could be towed from the Antarctic to places experiencing freshwater shortages.  The feasibility of such a scheme is still the subject of studies that nowadays include sophisticated computer modeling.

Places like the Persian Gulf, Cape Town, South Africa, and Perth, Australia all experience water shortages and could benefit tremendously from having a large iceberg towed to their waters.

How big an iceberg would it take to quench the thirst of a city like Cape Town?  Computer models show that an iceberg 2,000 feet long and 650 feet thick could produce enough water to supply the city for more than a year.  However, with water temperatures in the 60s in the area, even such a large iceberg would melt away within weeks.  So, to get enough water for a year, it would require a much larger iceberg – one at least a couple of miles long.

Daunting problems include figuring out how many and what sort of ships would be required.  An alternative to such giant icebergs would be finding a way to insulate the icebergs so they don’t melt as quickly, thereby allowing much smaller and more towable icebergs to be harvested.

Beyond these issues, there are the ecological issues of the effects of huge amounts of very cold fresh water affecting local marine ecosystems. 

Despite a wide range of challenges, there is continued interest in the idea of using icebergs as a source of very pure fresh water.  In an increasingly thirsty world, it might someday actually happen.

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Can icebergs be towed to water-starved cities?

Photo, posted November 1, 2007, courtesy of M A Felton via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Geothermal Power In The Energy Transition | Earth Wise

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The heat beneath the earth represents a vast repository of energy that in principle could provide for a significant part of our needs.  In some places, geothermal energy is easy to get to and is already being exploited.  California and Nevada operate dozens of geothermal electric generating plants.  Boise Idaho heats 92 of its biggest buildings with the river of hot water that flows 3,000 feet below the city.  In total, the U.S. produces enough geothermal electricity to power more than a million homes.

But all these examples make use of relatively rare local features that are not available to the great majority of locations.  As a result, geothermal energy has generally not been viewed as being able to play a major role in the alternative energy transition.

A number of experts around the world disagree with this assessment.  To a fair extent due to the deep-drilling techniques and knowledge about underground formations developed by the oil and gas industry during the fracking boom, there is growing interest in a type of geothermal energy called deep geothermal that accesses hot temperatures in the earth’s mantle as far down as two or three miles.

Deep geothermal can either access extremely hot water that exists down at those depths or water can be injected into hot rock down there, which is a technology known as enhanced geothermal systems.

There is enormous untapped potential for geothermal energy.  A 2019 report by the U.S. Department of Energy says that by 2050, geothermal could provide 8.5% of the United States’ electricity as well as direct heat.  Geothermal could be an important part of the so-called all-of-the-above future energy strategy.

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Can Geothermal Power Play a Key Role in the Energy Transition?

Photo, posted August 2, 2008, courtesy of ThinkGeoEnergy via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Restoring Environmental Rules Will Take Time | Earth Wise

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Over the previous four years, the Trump administration weakened or rolled back more than 100 rules and regulations on air, water, public lands, endangered species, and climate change.  The Biden administration has vowed to review these changes and restore the environmental protections that were removed or weakened.

The process of restoring environmental protections generally fall into a few broad categories.  Some changes can happen by executive order.  The President can cancel individual fossil fuel infrastructure projects or reinstate federal protection of specific places.  On his first day in office, President Biden rescinded the construction permit for the Keystone XL pipeline.

The President is also expected to restore federal protection to the Bears Ears and Grand Staircase-Escalante national monuments in Utah, which the Trump administration opened up to mining, logging, and drilling.

However, it could take two years or more to restore Obama-era climate change regulations including limits on emissions, rules on industrial emissions of toxic pollutants such as mercury, and protections on wetlands and waterways.

Reinstating comprehensive regulations on air, water, and climate pollution will take years because the Trump administration, rather than eliminating rules entirely, often replaced them with weaker regulations.  Replacing the weak regulations cannot just happen by executive order.  The process involves scientific and economic analysis, and that takes time.

After four years of shrinking budget and shrinking staff, the Environmental Protection Agency has a lot of catching up to do and will need to prioritize its actions in order to deal with the most damaging consequences of the previous administration.

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Restoring Environmental Rules Rolled Back by Trump Could Take Years

Photo, posted September 25, 2012, courtesy of Tar Sands Blockade via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Wildfire Smoke And Dangerous Microbes | Earth Wise

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The worsening severity of wildfires across the globe is a major public health concern.  The pulmonary and cardiovascular consequences of wildfire smoke inhalation have been well researched and have been an increasing focus for officials in places like California, other western states, and Australia.  More recently, another public health concern has emerged related to the fact that wildfire smoke can carry microbes that cause infectious diseases.

A new analysis, published in the journal Science, points out that the risk of potential infection from airborne microbes has not been the subject of much research.

The fungus coccidioides, for example, becomes airborne when soils are disturbed by fire. When this fungus is inhaled, it can cause Valley fever, an infection with flu-like symptoms that sometimes progresses to pneumonia or meningitis.  Inhalation risk of these microbes is highest closest to fires, so coccidioidomycosis is listed as a professional risk for firefighters.

A recent study found an increase in cases of invasive mold infection, aspergilliosis, as well as cases of coccidioidomycosis at hospitals within 200 miles of major wildfires in California.

Wildfire smoke has been shown to carry airborne particles of fungal and bacterial cells, hitching a ride on water vapor or charred carbon, over thousands of miles.  Some microbes in soil appear to be tolerant of or even thrive under high temperatures following wildfires.

A multidisciplinary research collaboration is needed to better understand the relationship between microbes, wildfire, and public health.  Such knowledge is increasingly vital as severe wildfires become seasonal norms in parts of the world such as the United States and Australia.

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Wildfire Smoke Can Carry Dangerous Microbes Thousands of Miles, Scientists Warn

Photo, posted September 9, 2020, courtesy of Christopher Michel via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Rivers Changing Color | Earth Wise

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A recent study, published in Geophysical Research Letters, found that one-third of large American rivers have had significant changes of color over the past 30 years.  Rivers can appear to be shades of blue, green, and yellow and we tend to expect healthy rivers to have colors in shades of blue.  According to the new study, only 6% of American rivers are dominantly blue.

The study looked at 235,000 Landsat images taken from 1984 to 2018.  The results are that 56% of rivers studied were dominantly yellow, 38% dominantly green, and 6% blue.  Over the 34 years studied, 33% of the rivers had significant changes in color. About 21% became greener and 12% more yellow. 

The chief causes of color changes in rivers are farm fertilizer runoff, dams, efforts to fight soil erosion, and climate change.  Climate change increases water temperature and rain-related runoff.

Color changes are not necessarily a sign of poor river health, but dramatic changes could point to issues that need attention.  A river can change color based on the amount of sediment, algae, or dissolved organic carbon in the water.   If a river becomes greener, it can often mean large algae blooms are present that cause oxygen loss and can produce toxins.  On the other hand, rivers that are getting less yellow demonstrate the success of regulations to prevent soil erosion.

The study of river colors can pinpoint which rivers are undergoing rapid environmental change.  What the study does not provide is information on water quality.  Water quality measurements will be important to determine the health of many of the rapidly changing rivers.

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One Third of U.S. Rivers Changed Their Color, Three Decades of Satellite Images Show

Photo, posted July 6, 2016, courtesy of Jeffrey Beall via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Mollusks And Microplastics | Earth Wise

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Plastic debris comes in all different shapes and sizes, but pieces that are less than five millimeters in length are called microplastics.  Microplastics are everywhere, including in the food we eat, the water we drink, and the air we breathe.

Much of the oceanic microplastic pollution comes from the breakdown of plastic litter.  Another source of microplastic pollution is microbeads.  Microbeads, which are sometimes added to cleansing and exfoliating personal care products, pollute the environment when they get flushed down the drain.  

According to a new study by researchers at Hull York Medical School and the University of Hull in the U.K., mussels, oysters and scallops have the highest levels of microplastic contamination among seafood.  The research team examined 50 studies between 2014 and 2020 to determine the levels of microplastic contamination globally in fish and shellfish.  The team found that microplastic content was 0-10.5 microplastics per gram in mollusks, 0.1-8.6 microplastics per gram in crustaceans, and 0-2.9 microplastics per gram in fish.  

The researchers found that mollusks collected off the coasts of Asia were the most heavily contaminated with microplastics.  China, Australia, Canada, Japan and the United States are among the largest consumers of mollusks, followed by Europe and the U.K.

While the human health implications of consuming microplastics are not well understood, early evidence from other studies suggest they do cause harm. 

According to the research team, more data is needed from different parts of the world in order to better understand how microplastics vary between different oceans, seas, and waterways.

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Highest levels of microplastics found in molluscs, new study says

Photo, posted September 3, 2007, courtesy of Andrew Malone via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Caspian Sea And Climate Change | Earth Wise

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According to the National Oceanic and Atmospheric Administration, global sea levels have been rising over the past century, and the rate has increased in recent decades.  Sea levels are currently rising about one-eighth of an inch every year.

Sea level rise is caused primarily by two factors related to climate change:  the added water from melting glaciers and ice sheets, and the expansion of seawater as it warms.  While climate change is causing global sea levels to rise, higher temperatures in other regions are having exactly the opposite effect.  The water levels are falling.

According to researchers from the University of Bremen in Germany, the Caspian Sea is a perfect example of how a body of water will change.  While it is named a sea due to its size and high salinity, the Caspian Sea is actually a lake.  In fact, it’s the largest lake in the world.  Its largest inflow is the Volga River and it has no natural connection to the ocean.  Its water level is determined by the proportional influences of inflow, precipitation, and evaporation.  Climate change is causing increased evaporation, which leads to a declining water level. 

According to the research team, the water level of the Caspian Sea could fall by 29 to 59 feet during this century.

The Caspian Sea is surrounded by Kazakhstan, Turkmenistan, Iran, Azerbaijan and Russia.  It’s an important regional water reservoir, and a biological and commercial center. 

The researchers hope the Caspian Sea will be used as an example in scientific research to assess the vulnerability of other regions to falling water levels.

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Climate crisis is causing lakes to shrink

Photo, posted October 31, 2016, courtesy of Amanderson2 via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Search For Lingering Ash | Earth Wise

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Ash trees are some of the most important plants along riverbanks and in wetlands.  There are three ash species in North America:  the white, green, and black ash.  Unfortunately, all three species are critically endangered because of the emerald ash borer.

The emerald ash borer is an exotic beetle from Asia that first showed up in the U.S. in southeastern Michigan in the summer of 2002.  The adult beetles do little damage but the larvae feed on the inner bark of ash trees and disrupt the tree’s ability to transport water and nutrients.  The beetles are now found in 35 states and 5 Canadian provinces and have killed hundreds of millions of ash trees.

The greatest hope for preserving ash tree species relates to lingering ash, which are those rare trees that have managed to survive the onslaught of the emerald ash borer. The idea is that those trees have some natural genetic resistance to the borer.  Getting seeds and cuttings from lingering ash and propagating them at nurseries may be the only way to get ash trees back into the natural landscape.

Lingering ash are extremely rare and therefore very hard to find.  As a result, researchers are reaching out to the public to help with the search and report the presence of these surviving trees in woodlands.

Researchers want to find large, mature trees left among those that were killed by the invasive insect and therefore display great resilience.  In Kentucky, university and Division of Forestry researchers are making use of software tools to engage the assistance of the public. An app called TreeSnap allows people to provide data on trees that they find in their community, on their property, or out in the wild.

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Researchers Ask Public for Help Finding Lingering Ash Trees

Help Our Nation’s Trees!

Photo, posted May 31, 2014, courtesy of Katja Schulz via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

WAMC Northeast Public Radio

WAMC/Northeast Public Radio is a regional public radio network serving parts of seven northeastern states (more...)