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Melting Snow Banks Reveal Contaminants

July 13, 2015

CEE Associate Professor Ferdi Hellweger explains how the last remaining snow banks from Boston's record breaking winter show just how many contaminants effect our surface water.

Source: iNSolution

News out­lets from The New York Times to WBUR have been run­ning com­men­tary lamenting the once 75-​​foot-​​high garbage-​​laden snow mound ensconced in Boston’s Sea­port Dis­trict since a record 110.6 inches of the white stuff fell here this winter. But Northeastern’s Ferdi Hell­weger, asso­ciate pro­fessor of civil and envi­ron­mental engi­neering, sees if not a silver lining then at least a cru­cial lesson in that fallout from the clouds.

That mound, which con­tains a lot of con­t­a­m­i­nants, will drain into Boston Harbor,” says Hell­weger, who studies microbial-​​related prob­lems in sur­face water, including cyanobac­teria, which pro­duce neu­ro­toxins that can kill dogs and other ani­mals if ingested. “Now that people see the dirt, they are raising a lot of con­cerns. But these contaminants—the dirt from the street, the soot from cars—are in the stormwater every time it rains. It’s just that now we see them because we are putting them on display.”

The soaring stack of ice and debris—everything from man­hole covers to half-​​eaten yogurts to parking meters—has now shrunk to a measly two to four feet, thanks to the recent humidity, the Boston Mayor Martin J. Walsh’s press office told us. The removal of an aston­ishing 276.17 tons of trash as of July 7 hasn’t hurt, either.

In fact, all that trash may have has­tened the tow­ering tundra’s demise, says Hellweger.

The dirt, the organics, they changed the color of the pile—we are no longer looking at bright-​​white freshly fallen snow,” he says, in per­haps the under­state­ment of the year. And the color, he explains, affects the “albedo”—how the sun reflects off a surface.

White snow reflects the sun­light, dark snow absorbs the sun­light,” he says. The more sunlight-​​cum-​​heat absorbed, the faster the melt.

In the end—and Boston, thank good­ness, is nearing the end of this story—what many saw as an eye­sore is actu­ally an envi­ron­mental wake-​​up call. The pol­lu­tants from all that gunk—the heavy metals in street dirt, the nutri­ents, such as phos­phorus in organic material—fuel the pro­duc­tion of bac­te­rial blooms. “We don’t see these con­t­a­m­i­nants because they get dis­solved in the rain and flushed down the drain—out of sight out of mind,” says Hell­weger. “Finally we get to see what’s being washed off our streets.”