How does turbulence make a cup of coffee taste better? Why do strong winds from certain directions cause crabs to scramble out of the water in Chesapeake Bay? What's the best way to pursue a career in environmental law? These were some of the questions answered for 43 sophomores and juniors from Cambridge Rindge and Latin High School who recently visited the Ralph M. Parsons Lab for environmental activities.
The event was sponsored by the Department of Civil and Environmental Engineering (CEE) and Alpha Phi Alpha service fraternity, including members Zeno Bain, a senior in CEE; Craig Robinson, a senior in management, and Jeffrey Malcolm, a junior in chemical engineering.
Assistant Professor Bettina Voelker of CEE used a simple array of beakers, fluids and pipettes to demonstrate how different types of soils can exacerbate or mollify the effects of acid rain.
Parsons Lab Director Harold Hemond emphasized the need for four years of high school math in preparing for environmental science careers, to the delight of CRLS chemistry teacher Ed McGillicuddy. Dramatic pictures of rain forest destruction as seen from the space shuttle moved students to ask CEE Assistant Professor Elfatih Eltahir what they could do to help stop the devastation.
CEE Assistant Professor Heidi Nepf illustrated the complex field of turbulence and fluid flow with everyday materials. She explained how turbulence in a cup of coffee redistributes the sugar from the bottom of the cup, and she drew pictures of eddies behind spoons. Using a hair dryer to simulate wind, she showed ther students how wind creates circulation in a lake. In the demonstration tank, blobs of red dye were used to show the movement of the water. A second tank with a layer of salty blue water resting under a layer of lighter fresh water produced slow rippling waves at the interface of the two layers in the middle.
Professor Nepf also answered the seemingly puzzling question of why crabs sometimes leap out of Chesapeake Bay. A layer of heavy, oxygen-depleted (anoxic) water lies on the bottom of the bay, but when wind blows across the bay, this heavy water can get pushed up to the top, she said. Crabs near the surface cannot breathe in the new anoxic environment, so they flee onto land, into the nets of waiting fishermen who have learned to recognize this phenomenon as an opportunity for large catches.
After lunch and informal questions with the professors and MIT students, the guests divided into small groups for a scientific and negotiating exercise created by Professor Nepf. Given information about a disease cluster in a hypothetical town, they tried to figure out the best way to track down possible contamination sources. For added realism, they were constrained by a theoretical budget which forced them to make tradeoffs between research and available funding.
A version of this article appeared in MIT Tech Talk on February 12, 1997.