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March 7, 2005 Vol. 76, no.
8S
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| WATER MYSTERY:
Environmental studies senior John Nguyen instructs volunteers in
how to take a water sample, and (bottom) a volunteer takes a sample
from Lake Merritt. The Lake Merritt Project hopes to find the cause
of the lake's algae blooms.
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Taking the
(blue-green algae) bloom out of Oakland's Lake Merritt
Engineers for Sustainable World project hopes to identify
lake's polluting source
Last Saturday morning, a
group of volunteers stood on a footbridge above Glen Echo Creek in the
Oakland hills. The creek flows down into Lake Merritt, a man-made lake
in the heart of downtown Oakland. Lake Merritt occasionally gets blue-green
algae blooms (especially after springtime rains), which cause aerobic
bacteria to grow. The bacteria deplete the lake's oxygen and kill off
aquatic organisms as it decomposes the dying blooms.
"It's essentially causing a lake death," says John Nguyen, an environmental
sciences senior in the College of Letters and Science. "So we're collecting
and analyzing water samples from different watersheds to find out the
source." By source, Nguyen means whatever is dumping nitrates into the
water to cause the algae-blooms.
The Lake Merritt Project began a year ago and is co-sponsored by the
student group Engineers for a Sustainable World. (Though no Berkeley
engineers participated in this outing, they've helped in the past, says
Nguyen.) The goal of the project is to identify the source and then,
in usual engineering fashion, seek a solution.
"I got involved because
I wanted to do research that was local," says Nguyen, who is the project's
coordinator. "Plus, my girlfriend and I used to take walks around Lake
Merritt so it's sentimental."
Nguyen's hypothesis is that the nitrate source is coming from the area's
golf course, specifically from the fertilizer used to keep the greens
green. While the data are still being analyzed, Nguyen says he's noticed
a lot of nitrates in the upper watershed, that is, few in the creek
water before the golf course, and quite a few in the sampling locations
downstream from the golf course.
To take samples, a volunteer dips a jar -- duct-taped to a long pole
-- in the creek three times. On the fourth dip, she collects the water
and brings it back to Nguyen's car. There, the group fills a 10mL vial
and mixes in acid and cadmium powder to isolate the nitrates. A colorimeter
measures the nitrate level. The group found .04 parts per million (ppm)
of nitrates from the footbridge location, which is above the golf course.
Where the creek flowed into the lake, nitrates measured at .86 ppm.
Project volunteers will now spend the next several months analyzing
the data. "When people at the lake ask us what we're doing, we tell
them and they get excited," says Nguyen. "That's the best part of this
project."
You, too, can help your local environment. Volunteer!
For more information, go to http://www.ce.berkeley.edu/~esw/.
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