Dartmouth Engineer - The Magazine of Thayer School of EngineeringDartmouth Engineer - The Magazine of Thayer School of Engineering

Lab Reports

How Good is Well Water?

Dartmouth received a $93,000 grant to determine what proportion of households with private wells in New Hampshire test their drinking water and what factors keep some households from testing more often. “We want to learn how to empower well-water users with the tools and information they need to keep their drinking water safe for themselves and their families,” says project leader and Dartmouth engineering Professor Mark Borsuk.

Close to 40 percent of New Hampshire’s 1.3 million people use private wells for drinking water. Currently 95 percent of new wells are drilled into bedrock, since outmoded dug wells were ripe for runoff contamination. But drilling deep comes at a price. Water that has been soaking in bedrock contains elements that naturally occur in the Earth’s crust, including contaminants such as arsenic and radon.

Kids drinking water
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Approximately one in five of New Hampshire’s wells contain unsafe levels of arsenic, which, even at low doses, has been associated with skin, bladder, and lung cancers and other harmful health effects.

A U.S. Geological Survey study released in June estimates that nearly 50,000 people in southeastern New Hampshire could be drinking water with elevated levels of arsenic.

“There’s no visual cue in their water, there’s no immediate health impact. So people may have lived with arsenic in their water for years and years and not had any problem,” says Borsuk.

“We will use the findings of our survey to identify the major factors contributing to water testing and treatment as well as to identify specific subpopulations at risk. These will be used to design initiatives to improve well-water testing and treatment,” says Borsuk.

In July researchers gathered and analyzed the results to help design cost-effective, targeted initiatives to help well-using residents protect their drinking water. During the stages of analysis, Borsuk’s team determined that the possible presence of arsenic was a specific concern for 73 percent of respondents. The team also determined that only about half of the respondents who treat their water with the intent to remove arsenic actually have treatment systems that are effective.

“There are many problems for which technical solutions exist, but which are not being solved because, for one reason or another, people don’t adopt the available technologies,” Borsuk says. “One line of my research is concerned with understanding these barriers to adoption and how to overcome them, either through improved design or through policy interventions.”

The next steps, Borsuk says, are to compare statewide estimates of testing and treatment rates to other available sources of information, including anecdotal information from labs and published results from other states, evaluate the stated motivations or barriers to testing and treatment for the identified target populations, further examine the types of water treatment systems being used, and ultimately design intervention strategies to overcome identified barriers to testing and treatment.

—Kathryn LoConte Lapierre

 

Modeling Airline Travel and Delays

Airline Delays
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Need something to read the next time you’re stuck at an airport? Pick up “Modeling Passenger Travel and Delays in the National Air Transportation System,” a study recently published by Thayer engineering Professor Vikrant Vaze, Cynthia Barnhart of MIT, and Douglas Fearing of the University of Texas at Austin in the journal Operations Research.

Unlike previous studies that only examined flight-centric measures of delays, Vaze’s research also analyzed delays that passengers encountered because of missed connections or flight cancellations. Using data from 2007, the last boom year for air travel, Vaze and his colleagues developed a model for estimating historical passenger travel and extended a previously developed method for estimating passenger delays.

“The results from the study can be used to motivate policy and investment decisions for the National Air Transportation System,” says Vaze. “We expect our passenger-centric approach to be applied in additional contexts where previously only flight information has been available.”

Analyzing a complicated network in which even minor delays can cause a ripple effect of missed connections and further delays, Vaze and his colleagues found that:

Vaze and his colleagues plan to further analyze flight and passenger data to better understand how airline network structures and scheduling decisions impact passengers and how policy changes could affect airlines and passengers.

—Kirsten Mabry

 

Ash from Forest Fires Melts Ice in Greenland

Global warming isn’t the only contributor to the melting of the Greenland ice sheet. A Dartmouth-led study links large-scale surface melting in 1889 and 2012 to rising temperatures and ash from Northern Hemisphere forest fires.

Dartmouth engineers supervised by Professor Mary Albert, co-author of the study and director of the U.S. Ice Drilling Program Office, analyzed six Greenland shallow ice cores.

“The widespread melting of the Greenland ice sheet required the combination of a lowered snow albedo from ash and unusually warm temperatures to push the ice sheet over the threshold,” says Thayer Ph.D. graduate Kaitlin Keegan Th’14, the study’s lead author and an advisee of Professor Ian Baker.

With the ash-filled snow reflecting less light than pure snow, melting increases. Researchers project that by the end of the century, the Greenland ice sheet may experience large-scale melts nearly annually.

 

Microplastics Accumulate in Arctic Sea Ice

Plastic Debris Trapped in Arctic Sea Ice
Plastic debris found in Arctic sea ice. Photo courtesy of Y.-Q. Wong and A. Khitun/Dartmouth College.

When Professor Rachel Obbard Th’06 melted Arctic sea ice to count microscopic algae beneath the surface, she found something more than she was looking for: tiny pieces of plastic.

Estimating that there were as few as 38 and as many as several hundred pieces of microplastic particles per cubic meter, she says, “It was such a surprise to me to find them in such a remote region. These particles have come a long way.”

Obbard and her colleagues gathered four ice cores during Arctic expeditions in 2005 and 2010. The researchers melted portions of the cores, filtered the water, and placed the sediments under a microscope. Using an infrared spectrometer, they determined the chemistry of the particles, which included rayon, polyester, nylon, polypropylene, acrylic, and polyethylene.

As global warming melts Arctic ice, “there will be microplastic particles dumped back into the Arctic Ocean that have been entrapped in ice for several years,” Obbard says.

“I was really shocked and saddened,” she says. “I guess I, like most people, still consider the Arctic to be a pristine and remote area, and clearly our pollution has reached even it.”

 

Undergraduate Design Competition

The engineering student group of Siddharth Agrawal ’14, Arlinda Rezhdo Th’14, and Xiaotian Wu ’14, advised by Professor Alexander Hartov Th’88, won the 2014 Northeast Bioengineering Conference Undergraduate Design Competition in April. For their ENGS 89/90 project—“Multilayered Phantom for Electrical Impedance Measurements of a Fetal Heartbeat”—they developed a physical model of the human womb and fetus for use in researching ways to monitor fetal heart rate.

For more photos, visit our Research and Innovations album on Flickr.

Categories: The Great Hall, Lab Reports

Tags: award, climate change, complex systems, design, engineering in medicine, environment, faculty, projects, public policy, research, students

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