Desalination Breakthrough Turns Seawater Into Drinking Water
Turning seawater into drinking water just became more feasible. Scientists at the University of Manchester in the UK have developed graphene oxide membranes with holes small enough to filter out salt. The sieves represent a technological breakthrough in the effort to make desalination more efficient and affordable.
Graphene oxide membranes have been used in desalination experiments for years, but never before has the sieve been small enough to filter out smaller particles.
One of the major challenges with this process is the natural tendency of graphene oxide membranes to swell in water. This causes their pores to expand, and salt particles to pass through. The scientists, led by Rahul Nair, were able to control the swelling by building epoxy resin walls around the membranes, as noted in the study published in Nature Nanotechnology.
"Realization of scalable membranes with uniform pore size down to atomic scale is a significant step forward and will open new possibilities for improving the efficiency of desalination technology," Nair said. "This is the first clear-cut experiment in this regime. We also demonstrate that there are realistic possibilities to scale up the described approach and mass produce graphene-based membranes with required sieve sizes."
According to the International Water Association, thousands of desalination plants currently exist worldwide, but the process remains expensive.
Earth's oceans contain 97 percent of the planet's water, the National Ocean Service estimates. To paint a picture of the total amount of salt in the oceans, NOAA said that "if the salt in the ocean could be removed and spread evenly over the Earth's land surface, it would form a layer more than 500 feet thick, about the height of a 40-story office building."
According to a United Nations report:
• Around 700 million people in 43 countries suffer today from water scarcity.
• By 2025, 1.8 billion people will be living in countries or regions with absolute water scarcity, and two-thirds of the world's population could be living under water stressed conditions.
• With climate change, almost half the world's population will be living in areas of high water stress by 2030.
In an article accompanying the scientists' research, Ram Devanathan, from the Pacific Northwest National Laboratory, said the next step toward scaling the desalination process would be to test the durability of the graphene oxide membranes.
"The selective separation of water molecules from ions by physical restriction of interlayer spacing opens the door to the synthesis of inexpensive membranes for desalination," Devanathan said. "The ultimate goal is to create a filtration device that will produce potable water from seawater or wastewater with minimal energy input."
Returning the ‘Three Sisters’ – Corn, Beans and Squash – to Native American Farms Nourishes People, Land and Cultures
By Christina Gish Hill
Historians know that turkey and corn were part of the first Thanksgiving, when Wampanoag peoples shared a harvest meal with the pilgrims of Plymouth plantation in Massachusetts. And traditional Native American farming practices tell us that squash and beans likely were part of that 1621 dinner too.
Abundant Harvests<p>Historically, Native people throughout the Americas bred indigenous plant varieties specific to the growing conditions of their homelands. They selected seeds for many different traits, such as <a href="https://emergencemagazine.org/story/corn-tastes-better/" target="_blank" rel="noopener noreferrer">flavor, texture and color</a>.</p><p>Native growers knew that planting corn, beans, squash and sunflowers together produced mutual benefits. Corn stalks created a trellis for beans to climb, and beans' twining vines secured the corn in high winds. They also certainly observed that corn and bean plants growing together tended to be healthier than when raised separately. Today we know the reason: Bacteria living on bean plant roots pull nitrogen – an essential plant nutrient – from the air and <a href="http://www.tilthalliance.org/learn/resources-1/almanac/october/octobermngg" target="_blank" rel="noopener noreferrer">convert it to a form that both beans and corn can use</a>.</p><p>Squash plants contributed by shading the ground with their broad leaves, preventing weeds from growing and retaining water in the soil. Heritage squash varieties also had spines that discouraged deer and raccoons from visiting the garden for a snack. And sunflowers planted around the edges of the garden created a natural fence, protecting other plants from wind and animals and attracting pollinators.</p><p>Interplanting these agricultural sisters produced bountiful harvests that sustained large Native communities and <a href="http://dx.doi.org/10.1353/eam.2015.0016" target="_blank">spurred fruitful trade economies</a>. The first Europeans who reached the Americas were shocked at the abundant food crops they found. My research is exploring how, 200 years ago, Native American agriculturalists around the Great Lakes and along the Missouri and Red rivers fed fur traders with their diverse vegetable products.</p>
Displaced From the Land<p>As Euro-Americans settled permanently on the most fertile North American lands and acquired seeds that Native growers had carefully bred, they imposed policies that <a href="https://doi.org/10.1086/ahr/87.2.550" target="_blank">made Native farming practices impossible</a>. In 1830 President Andrew Jackson signed the <a href="https://guides.loc.gov/indian-removal-act" target="_blank">Indian Removal Act</a>, which made it official U.S. policy to force Native peoples from their home locations, pushing them onto subpar lands.</p><p>On reservations, U.S. government officials discouraged Native women from cultivating anything larger than small garden plots and pressured Native men to practice Euro-American style monoculture. Allotment policies assigned small plots to nuclear families, further limiting Native Americans' access to land and preventing them from using communal farming practices.</p><p>Native children were forced to attend boarding schools, where they had no opportunity to <a href="https://doi.org/10.5749/jamerindieduc.57.1.0145" target="_blank">learn Native agriculture techniques or preservation and preparation of Indigenous foods</a>. Instead they were forced to eat Western foods, turning their palates away from their traditional preferences. Taken together, these policies <a href="https://kansaspress.ku.edu/978-0-7006-0802-7.html" target="_blank" rel="noopener noreferrer">almost entirely eradicated three sisters agriculture</a> from Native communities in the Midwest by the 1930s.</p>
Reviving Native Agriculture<p>Today Native people all over the U.S. are working diligently to <a href="https://www.oupress.com/books/15107980/indigenous-food-sovereignty-in-the-united-sta" target="_blank" rel="noopener noreferrer">reclaim Indigenous varieties of corn, beans, squash, sunflowers and other crops</a>. This effort is important for many reasons.</p><p>Improving Native people's access to healthy, culturally appropriate foods will help lower rates of <a href="https://www.cdc.gov/vitalsigns/aian-diabetes/index.html" target="_blank">diabetes</a> and <a href="https://www.apa.org/pi/oema/resources/ethnicity-health/native-american/obesity" target="_blank">obesity</a>, which affect Native Americans at disproportionately high rates. Sharing traditional knowledge about agriculture is a way for elders to pass cultural information along to younger generations. Indigenous growing techniques also protect the lands that Native nations now inhabit, and can potentially benefit the wider ecosystems around them.</p>
EcoWatch Daily Newsletter
By Jake Johnson
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