Climate change likely to boost insect activity and crop loss

September 1, 2018 in Blog

Scientists have already cautioned that climate change will likely impact the food we grow. From increasing global temperatures to more frequent “extreme” weather actions like droughts and floods, climate change is expected to negatively affect our ability to produce food for a growing human population.

Symptom of stem borer on corn cause by Ostrinia furnacalis

  • A new research says that climate change is expected to accelerate rates of crop loss due to the activity of another group of hungry creatures — insects. In a paper published Aug. 31 in the journal Science, a team led by scientists at the University of Washington reports that insect activity in today’s temperate, crop-growing regions will rise along with temperatures. Researchers project that this activity, in turn, will boost worldwide losses of rice, corn and wheat by 10-25 percent for each degree Celsius that global mean surface temperatures rise. Just a 2-degree Celsius rise in surface temperatures will push the total losses of these three crops each year to approximately 213 million tons.
  • “We expect to see increasing crop losses due to insect activity for two basic reasons,” said co-lead and corresponding author Curtis Deutsch, a UW associate professor of oceanography. “First, warmer temperatures increase insect metabolic rates exponentially. Second, with the exception of the tropics, warmer temperatures will increase the reproductive rates of insects. You have more insects, and they’re eating more.”
  • “Global warming impacts on pest infestations will aggravate the problems of food insecurity and environmental damages from agriculture worldwide,” said co-author Rosamond Naylor, a professor in the Department of Earth System Science at Stanford University and founding director of the Center on Food Security and the Environment. “Increased pesticide applications, the use of GMOs, and agronomic practices such as crop rotations will help control losses from insects. But it still appears that under virtually all climate change scenarios, pest populations will be the winners, particularly in highly productive temperate regions, causing real food prices to rise and food-insecure families to suffer.”
  • To investigate how insect herbivory on crops might affect our future, the team looked at decades of laboratory experiments of insect metabolic and reproductive rates, as well as ecological studies of insects in the wild. Unlike mammals, insects are ectothermic, which means that their body temperature tracks the temperature of their environment. Thus, the air temperature affects oxygen consumption, caloric requirements and other metabolic rates.
  • The past experiments that the team studied show conclusively that increases in temperature will accelerate insect metabolism, which boosts their appetites, at a predictable rate. In addition, increasing temperatures boost reproductive rates up to a point, and then those rates level off at temperature levels akin to what exist today in the tropics.
  • Deutsch and his colleagues found that the effects of temperature on insect metabolism and demographics were fairly consistent across insect species, including pest species such as aphids and corn borers. They folded these metabolic and reproductive effects into a model of insect population dynamics, and looked at how that model changed based on different climate change scenarios. Those scenarios incorporated information based on where corn, rice and wheat — the three largest staple crops in the world — are currently grown.
  • For a 2-degree Celsius rise in global mean surface temperatures, their model predicts that median losses in yield due to insect activity would be 31 percent for corn, 19 percent for rice and 46 percent for wheat. Under those conditions, total annual crop losses would reach 62, 92 and 59 million tons, respectively.
  • The researchers observed different loss rates due to the crops’ different growing regions, Deutsch said. For example, much of the world’s rice is grown in the tropics. Temperatures there are already at optimal conditions to maximize insect reproductive and metabolic rates. So, additional increases in temperature in the tropics would not boost insect activity to the same extent that they would in temperate regions — such as the United States’ “corn belt.”
  • The team notes that farmers and governments could try to lessen the impact of increased insect metabolism, such as shifting where crops are grown or trying to breed insect-resistant crops. But these alterations will take time and come with their own costs.

Source: University of Washington


Green process stops water use, pollution in textile industry

August 27, 2018 in Blog

A new totally green method is developed by researchers from the University of Calicut, Kerala, which can potentially get rid of using water for sizing and desizing cotton and polyster yarn. Textile industry requires immense amount of water and also one of the biggest water polluters.

Dr. Poovathinthodiyil Raveendran and team

The team of researchers led by Dr. Poovathinthodiyil Raveendran from the University’s Department of Chemistry has made the sizing and desizing process eco-friendly by using liquid and supercritical carbon dioxide instead of water, and sucrose octaacetate in place of starch. The results of the study were published in the journal ACS Sustainable Chemistry & Engineering.

Before the yarn is woven into fabric, it is coated with sizing agents to strengthen the yarn (to decrease breakages on the loom) and protect it from damage and reduce friction. Sizing also removes or smoothens the projecting microfibres that might interfere with the weaving process.

Traditionally, starch mixed in water is used for the sizing process, and this requires plenty of water. The used water is disposed of, leading to water pollution. “So we looked at changing the sizing process from a wet to a completely dry process,” says Dr. Raveendran. The researchers used liquid carbon dioxide as solvent and tested three agents that easily dissolve in carbon dioxide for sizing both cotton and polyester yarn.

Suitable agent

“Of the three agents tested, we found sucrose octaacetate produced the best results,” says Dr. Raveendran. The yarn had a smooth, glassy coating on the surface and the strength of the yarn (cotton and polyester) nearly doubled and the yarn exhibited improved mechanical properties essential for weaving. All the microfibres that protrude from the yarn were aligned and smoothened. The abrasion resistance also increased upon sizing.

The yarn after sizing has to be dried when water is used, making the entire process energy-intensive. But no drying is needed when liquid carbon dioxide is used as it is an inherently dry process. When the pressure of carbon dioxide is reduced to gas phase pressure, the carbon dioxide changes its state from a liquid to gas leaving the yarn dry. “The yarn becomes dry instantaneously,” he says.

Once the weaving is completed, the sizing agent has to be completely removed from the yarn as it might resist dyes and chemicals commonly used in textile processing. In the conventional desizing process, large volume of water is used for desizing or washing the fabric to remove the sizing agent from the yarn, which generates lots of waste water.

Instead of water, the researchers used supercritical carbon dioxide for desizing. “While both liquid and supercritical carbon dioxide have lower viscosity and surface tension compared with water, the molecular diffusion of supercritical carbon dioxide is 10 times more than liquid carbon dioxide,” says Dr. Raveendran. “The more the molecular diffusion, the faster will be the movement of molecules in the fluid and this determines the efficiency of cleaning.” The sizing agent dissolves in the supercritical carbon dioxide when it comes in contact with it.

As in the case of sizing, the yarn (in the fabric) becomes dry almost instantaneously when the pressure of carbon dioxide is reduced to gas phase pressure after desizing. And the sizing agent separates out from the yarn and settles at the bottom.

“The best part of this process is that it is zero-pollution, zero-waste as both carbon dioxide and the sizing agent (sucrose octaacetate), which is modified cane sugar, can be recycled endlessly,” says Dr. Raveendran. Following this the researchers are planning to extend the process and are looking at setting up a pilot plant to test the green process.





Air pollution reduces global life expectancy by more than one year

August 23, 2018 in Blog

Air pollution shortens human lives by more than a year, according to a new study from a team of leading environmental engineers and public health researchers. Better air quality could lead to a significant extension of lifespans around the world.

Upper panel a: How air pollution shortens human life expectancy around the world. Lower panel b: Gains in life expectancy that could be reached by meeting World Health Organization guidelines for air quality around the world.

This is the first time that data on air pollution and lifespan has been studied together in order to examine the global variations in how they affect overall life expectancy.

The researchers looked at outdoor air pollution from particulate matter (PM) smaller than 2.5 microns. These fine particles can enter deep into the lungs, and breathing PM2.5 is associated with increased risk of heart attacks, strokes, respiratory diseases and cancer. PM2.5 pollution comes from power plants, cars and trucks, fires, agriculture and industrial emissions.

Led by Joshua Apte in the Cockrell School of Engineering at The University of Texas at Austin, the team used data from the Global Burden of Disease Study to measure PM2.5 air pollution exposure and its consequences in 185 countries. They then quantified the national impact on life expectancy for each individual country as well as on a global scale.

The findings were published  in Environmental Science & Technology Letters.

“The fact that fine particle air pollution is a major global killer is already well known,” said Apte, who is an assistant professor in the Cockrell School’s Department of Civil, Architectural and Environmental Engineering and in the Dell Medical School’s Department of Population Health. “And we all care about how long we live. Here, we were able to systematically identify how air pollution also substantially shortens lives around the world. What we found is that air pollution has a very large effect on survival — on average about a year globally.”

In the context of other significant phenomena negatively affecting human survival rates, Apte said this is a big number.

“For example, it’s considerably larger than the benefit in survival we might see if we found cures for both lung and breast cancer combined,” he said. “In countries like India and China, the benefit for elderly people of improving air quality would be especially large. For much of Asia, if air pollution were removed as a risk for death, 60-year-olds would have a 15 percent to 20 percent higher chance of living to age 85 or older.”

Apte believes this discovery is especially important for the context it provides.

“A body count saying 90,000 Americans or 1.1 million Indians die per year from air pollution is large but faceless,” he said. “Saying that, on average, a population lives a year less than they would have otherwise — that is something relatable.”

Source: University of Texas, Austin



Contact lenses: Its impact on Environment

August 22, 2018 in Blog

Most of the people depend on contact lenses to improve their vision. But these sight-correcting devices don’t last forever – some of these devices are used for a short period of one day and are disposed in various ways.  Researches show that throwing these lenses down the drain after usage will contribute to microplastic pollution in waterways.

  • A team of researchers presented their results at the 256th National Meeting & Exposition of the American Chemical Society.
  • They started looking into the U.S. market and conducted a survey of contact lens wearers. They found that 15 to 20 percent of contact wearers are flushing the lenses down the sink or toilet. This is a pretty large number, considering roughly 45 million people in the U.S. alone wear contact lenses.


  • When the lenses are washed down the drain, they ultimately end up in wastewater treatment plants. The team estimates that anywhere from six to 10 metric tons of plastic lenses end up in wastewater in the U.S. alone each year. Contact lenses tend to be denser than water, which means they sink, and this could eventually pose a danger to aquatic life, especially bottom feeders that may ingest the contact lenses.
  • Analyzing what happens to these lenses is a challenge for several reasons. First, contact lenses are transparent, which makes them difficult to observe in the complicated setting of a wastewater treatment plant. Further, the plastics used in contact lenses are different from other plastic waste, such as polypropylene, which can be found in everything from car batteries to textiles. Contact lenses are instead frequently made with a combination of poly(methylmethacrylate), silicones and fluoropolymers to create a softer material that allows oxygen to pass through the lens to the eye. So, it’s unclear how wastewater treatment affects contacts.
  • These differences make processing contact lenses in wastewater plants a challenge. To help address their fate during treatment, the researchers exposed five polymers found in many manufacturers’ contact lenses to anaerobic and aerobic microorganisms present at wastewater treatment plants for varying times and performed Raman spectroscopy to analyze them. They found that there were noticeable changes in the bonds of the contact lenses after long-term treatment with the plant’s microbes. The team concluded that microbes in the wastewater treatment facility actually altered the surface of the contact lenses, weakening the bonds in the plastic polymers.
  • “When the plastic loses some of its structural strength, it will break down physically. This leads to smaller plastic particles which would ultimately lead to the formation of microplastics”, says Kelkhar one of the researchers.  Aquatic organisms can mistake microplastics for food and since plastics are indigestible, this dramatically affects the marine animals’ digestive system. These animals are part of a long food chain. Some finally find their way to the human food supply, which could lead to surplus human exposures to plastic impurities and pollutants that stick to the surfaces of the plastics.
  • With this research, the team hopes that industry will take note and at minimum, provide a label on the packaging describing how to properly dispose the contact lenses, which is by placing them with other solid waste. The researchers mention that, “Ultimately, we hope that manufacturers will conduct more research on how the lenses impact aquatic life and how fast the lenses degrade in a marine environment.”


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