|
06/08/2005
Visible Nets
Harmony is something that, unfortunately, is lacking in too many
parts of the world, the Middle East being just one example. In
the music world, I’ve rhapsodized over the harmonious efforts of
the Marco Island Choir down in Florida. I had not heard of the
Harmonium Choral Society here in my own backyard in New
Jersey until informed that our granddaughter Dale had won the
grand prize in Harmonium’s annual student composition contest.
Last Saturday night, Harmonium quickly became my second
favorite choral group with a stunning concert under the direction
of a compellingly enthusiastic director, Anne Matlack. The
group was wonderful, as was the world premiere of “Sing to the
Lord”, our granddaughter’s composition based on the 96th
Psalm. Starting in a chant-like style, it evolved into a jazzy
syncopated style, ending in a crescendo that brought down the
house. Lest you think Harmonium stands second to Marco in my
favorite choral groups, my all time favorite, politics aside, is the
old Red Army Chorus. Harmonium came close with their
renditions of two Russian pieces. I found that Ms. Matlack
actually sang in the Kremlin with the Yale Alumni Chorus.
Harmony seems badly lacking when it comes to our treatment of
the environment. It’s heartening to hear of an invention that
represents a step forward in the improvement of our marine
environment. Some of the best and most elegant inventions are
the simplest ones. Take, for example, the wheel, the paper clip
or those ubiquitous sticky pieces of paper that came out of the
labs at 3M. The invention of concern here came to my attention
in an article by Amanda Yarnell in the May 23 issue of Chemical
and Engineering News (C&EN). In April, the World Wildlife
Fund (WWF) honored Norman Holy for inventing a fishing net.
When I read about this fishing net, I thought of my recent CT
scan, a follow-up on kidney surgery a couple of years ago. An
unpleasant part of a CT scan of the abdomen is the need to drink
a couple glassfuls of barium sulfate. The barium sulfate provides
a contrast material that helps show up any disturbing features in
the abdomen. There weren’t any in my case, thankfully.
I’ve probably written before of another experience with barium
sulfate when a graduate student at the University of Pittsburgh
from 1946 to 1950. For my Master’s degree, my professor, W.
Edward Wallace, suggested that I determine the solubility of
barium sulfate in water over a range of temperatures. To do this,
I made a batch of barium sulfate using radioactive sulfur as a
tracer. I would take a sample of the barium sulfate solution,
place it in a little metal cup and evaporate the water to dryness.
By counting the radioactivity with a Geiger counter, I could tell
how much barium sulfate was in the solution.
I got some data but needed more barium sulfate and had to make
a new batch. When I measured the solubility of this new batch,
the data disagreed with my results from the first batch. At the
time, I had no idea what the trouble was and, when Wallace
offered me a grant to work on a completely different project for a
Ph.D., I eagerly accepted and never got a Master’s degree. Later,
I decided that my problem was that the two batches of barium
sulfate were composed of particles of different sizes.
In the year I got my Ph.D., 1950, N.V. Sidgwick of Oxford
University published a 1700-page, two-volume treatise titled
“Chemical Elements and Their Compounds”. It’s the first book I
use to check up on the properties of a chemical compound and,
this week I looked to see what Sidgwick had to say about barium
sulfate. I was dumbfounded, embarrassed and amazed to find the
following in a very short paragraph on the compound: “The
solubility depends on the particle size even more than with
calcium sulphate; the sol[ubility] of ordinary precipitated barium
sulphates is 0.22 mg/20 [degrees C], but that of the finest
particles obtainable (0.1 micron) was found to be 80 percent
greater than this.” Sidgwick cited three papers dating from 1893
to 1923. No wonder my two batches had different solubilities!
Had there been an Internet in those days, I would have typed the
words barium, sulfate, water and solubility into my search
engine. Those early papers would have appeared and I might
have a Master’s degree today. You say, “What does all this have
to do with the WWF and fishing nets?” One of the big problems
in commercial fishing is that the huge nets trap not only the fish
but also large numbers of dolphins and porpoises and, rarely, a
whale. Estimates of the number of porpoises and dolphins that
perish in the nets range from 80,000 to more than 300,000 and
about a dozen whales each year.
Enter Norman Holy and his colleagues Don King, a commercial
fisherman, and Ed Trippel, a Canadian fisheries scientist. Holy
is a polymer chemist who analyzes patents for Bristol Myers
Squibb but in his spare time worries about fishing nets and how
they can be made safer for the mammals that are inadvertently
their victims. He also is associated with Atlantic Gillnet Supply,
Inc., on whose Website I found several helpful papers.
The fishing net problem is threefold. First, if you were a
dolphin, would it help if you could see the net? The nylon nets
used in commercial fishing are virtually invisible in the water.
Holy and his crew came up with a net impregnated with, what
else, barium sulfate. As in my CT scan, barium sulfate makes
the net more visible, not only to the marine mammals’ eyes but
also to their ears. Dolphins and porpoises send out sound waves
and, like bats, measure how fast the waves are reflected back to
detect food and to navigate. The barium sulfate also makes the
nets stiffer, more brittle, which also seems to play a role in
diverting the dolphins.
Another problem when the nets trap a whale is that the so-called
“headropes”, the polypropylene ropes used to haul in the nets,
are too strong. When a whale gets trapped, it can’t break free.
The whale tends to roll to try to break free but with the strong
ropes it may just get more entwined. By working with the rope
manufacturers, headropes have been altered so that they break at
around 1,000 pounds instead of the former 2,000 to 3,000
pounds. With the weaker rope, the whale can break free.
A third problem is nets that are lost at sea. These nets continue
to catch fish and turtles. To address this problem, Holy has
worked on making polymers that would fall apart rather than
become entangled and that would biodegrade in the sea over
time. Holy stresses that chemistry, biology and fishing expertise
all play a role in trying to address these problems. For the sake
of the dolphins, porpoises and whales let’s hope the efforts of
Holy and his colleagues make a difference.
Finally, speaking of dolphins, an article by Randolph Schmid in
yesterday’s (June 7) Star Ledger shows a female dolphin with a
sort of cone-shaped sponge on its nose. Michael Kruetzen and
coworkers in Australia found that a bunch of these “spongers”,
mostly female dolphins, tear the sponges from the bottom of the
sea. They appear to use the sponges while foraging to protect
against stings from stonefish and other nasty critters on the sandy
bottom. The researchers conclude from studying groups of
spongers against non-spongers that the sponging females are
passing what they’ve discovered along to their children. Maybe
in the future they’ll teach their kids to avoid barium sulfate,
especially when it’s on a net!
Allen F. Bortrum
|
