Wednesday December 19, 2018
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Increase green cover to mitigate urban heat : NASA

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By NewsGram Staff Writer

Washington:  Providing a solution to the recent problem of rising urban heat, a recently conducted study by NASA explained how increasing the green cover can help cities to a great extent.

Cheetal_(spotted_deer)_at_Van_Vihar_National_Park

Using multiple satellites’ observations, researchers found that areas in the US covered in part by concrete surfaces had a summer temperature 1.9 degrees Celsius higher than surrounding rural areas.

In winter, the temperature difference was 1.5 degrees Celsius higher in urban areas.

At the human level, a rise of one degrees Celsius can raise energy demands for air conditioning in the summer from five to 20 percent.

“This has nothing to do with greenhouse gas emissions. It is in addition to the greenhouse gas effect. This is the land use component only,” said Lahouari Bounoua, research scientist at NASA’s Goddard Space Flight Centre in Greenbelt, Maryland.

The urban heat island effect occurs primarily during the day when urban impervious surfaces absorb more solar radiation than the surrounding vegetated areas, resulting in a few degrees temperature difference.

The urban area has also lost the trees and vegetation that naturally cool the air.

“Anywhere in the US, small cities generate less heat than mega-cities,” Bounoua said.

The reason is the effect vegetation has on keeping a lid on rising temperatures.

“The amount and type of vegetation plays a big role in how much the urbanisation changes the temperature,” added research scientist and co-author Kurtis Thome.

As a by-product of photosynthesis, leaves release water back into the atmosphere in a process called evapotranspiration, which cools the local surface temperature the same way that sweat evaporating off a person’s skin cools them off.

Trees with broad leaves have more pores to exchange water than trees with needles, and so have more of a cooling effect.

“So even though 0.3 degrees Celcius may seem like a small difference, it still may have impact on energy use,” Bounoua said, especially when urban heat island effects are exacerbated by global temperature rises due to climate change.

Understanding the tradeoffs between urban surfaces and vegetation may help city planners in the future mitigate some of the heating effects, the authors noted in a paper that appeared in the journal Environmental Research Letters.

(With inputs from IANS)

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Researchers Look for Alternatives To Chemical Fertilizers for a Cleaner Environment

Too many nutrients in the water leads to poor water quality by causing hazardous algal blooms.

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Fertilizers
A farming woman spreads fertilizer in a paddy field. Flickr

Fertilizer is made of nutrients like nitrogen and phosphorus. Chemical fertilizers require huge amounts of energy to produce. But there are other, natural and more readily available sources.

The University of Michigan, with support from the National Science Foundation, is working at making our water cleaner, and our agriculture more sustainable, by capturing one of those sources, rather than flushing it down the toilet.

On a hot summer afternoon near Brattleboro, Vermont, farmer Dean Hamilton has fired up his tractor and is fertilizing his hay field — with human urine.

It takes a bit of time to get used to, says environmental engineer Nancy Love.

“I’ve been surprised at how many people actually get beyond the giggle factor pretty quickly,” she said, “and are willing to listen.”

Fine-tuning the recycling

Rich Earth Institute, a nonprofit, is working with Love and her team. Abraham Noe-Hays says they are fine-tuning new methods to recycle urine into fertilizer.

“There’s a great quote by Buckminster Fuller about how pollution is nothing but the resources that we’re not harvesting, and that we allow them to disperse because we’ve been ignorant of their value,” he said.

Harvesting the resource of urine — which is, after all, full of the same nutrients as chemical fertilizer — will fix two problems at once: eliminate waste and create a natural fertilizer.

The Rich Earth Institute has been using urine as fertilizer since 2012. Kim Nace says they collect about 26,000 liters a year, thanks to a loyal group of dedicated donors.

“We now have people who have some source-separating toilets in their homes. We also have people who have 55 gallon (200-liter) barrels where they collect and then we transport to our farms, and we’ve also got a large urine depot,” Nace said.

`fertilizers
Fertilizers. Wikimedia Commons

They pasteurize the urine to kill any microbes, and then it is applied directly onto hay fields like Hamilton’s.

Next level of project

Now that they’ve partnered with the University of Michigan, Love says they’re looking to take their project to the next level.

“There are three things we really are trying to do with the urine in this kind of next phase. We’re trying to concentrate it. We’re trying to apply technologies to reduce odor, and we’re trying to deal with trace contaminants like the pharmaceuticals,” she said.

Dealing with pharmaceuticals is an important issue. Heat urine kills germs but has no effect on chemicals like drugs that pass through our bodies.

“We know pharmaceuticals are a problem for aquatic organisms and water systems,” Love said. “It’s debatable about the impact on human health at very, very low levels. Independent of that, I think most people would prefer that they not be in their food.”

Fertilizers
Farmer Scott Halpin is facing another year of high prices for seed and fertilizer, and low prices for the corn and soybeans his family is planting on farmland outside Morris, Illinois.

21st century infrastructure

For Love, this is all about redesigning our wastewater infrastructure for the 21st century. Too many nutrients in the water leads to poor water quality by causing hazardous algal blooms.

“Our water emissions are going into very sensitive water bodies that are vulnerable to these nutrient loads,” she said. “We need to change that dynamic. And if we can capture them and put them to a beneficial use, that’s what we’re trying to do.”

Also Read: Common Plastic Chemical May Increase Breast Cancer Risk

Their efforts could make agriculture greener and our waterways cleaner. (VOA)