in the northeast, Bawden notes. Howev- er, areas that experienced large vertical motions due to the extraction and

L.A. moves, but not in the way expected Researchers monitoring small ground

motions along faults in Southern Califor- nia ended up detecting an altogether dif- ferent phenomenon: the rise and fall of the ground as local governments pump billions of gallons of water into and out of the region’s aquifers.

In some spots-particularly in the 40- kilometer-long Santa Ana basin, southeast of Los Angeles-the ground rises and falls up to 11 centimeters over the course of a year. This periodic movement, which the scientists say isn’t linked to Southern Cal- ifornia’s earthquake activity, hasn’t been measured before, says Gerald W. Bawden, a geophysicist at the U S . Geological Sur- vey in Menlo Park, Calif. Satellitemounted instruments and a ground network of Global Positioning System (GPS) stations detected the rhythmic motion, which Bawden likens to breathing, during the past 6 years. He and his colleagues report their findings in the Aug. 23 NATURE.

More than 14 million people live in the metropolitan Los Angeles area. Add in all the golf courses, car washes, and industri- al activity of a large city and you’ve got a recipe requiring a lot of water. Throughout the year, utility districts in the region pump rainwater, as well as water diverted from the Colorado River and sources in northern California, into aquifers.

When demand for water is low, the un- derground reservoirs recharge and swell like a wet sponge, says Bawden. In the summer months, the net withdrawal of water from these aquifers causes the overlying ground to compact and subside. Because the ground doesn’t fully spring back when it’s recharged with water. Darts

recharge of water in aquifers showed horizontal movements of up to 14 mm during the course of a year.

Minster hails the new measurement of the direction and size of tectonic ground movement in the Los Angeles basin as “a major step forward in assessing the seis- mic hazards” of Southern California.

of the Santa Ana basin lose 12 m i b e - “When scientists set out to measure

some sGes to drop as Map of the Los Angeles area shows land subsidence in much as 9 meters, or summer of 1999. The largest drop, about 5.4 centimeters, 9,000 times normal, in was near downtown Santa Ana (arrow). The smallest drops the past century, he were in the north and are shown in blue and uiolet. adds.

Horizontal ground movements at loca- tions with little or no vertical change show that the southwestern portions of the Los Angeles basin are creeping about 4.4 mm each year toward the mountains

small quantities like ground motion, they often find unexpected phenomena like this,” says Bernard Minster, a geophysicist at the University of California, San Diego.

-S. Perkins

Chemists redesign natural antifreeze Chemists have created a family of syn-

thetic compounds akin to proteins that keep Arctic and Antarctic fish from freez- ing stiff. If the new molecules can work as well as the fish proteins do, they could of- fer a new route to protecting frozen foods and chilled transplant organs from de-

variation on natural antifreeze glycopro- teins, the team reports. Structural differ- ences among the variants might help re- veal the molecular motifs underlying the natural antifreeze proteins. Also, the variants might be more or less suited for sDecific anti-ice iobs. Ben savs.

structive ice buildip. Researchers discovered these SD.

called antifreeze proteins in the 1960s (SN: 4/19/97, p. 237). Scientists believe that the compounds bind to tiny ice crystals and make it harder for them to grow. Researchers have shown that the antifreeze proteins can thwart icecrystal formation when added to food.

Yet, researchers haven’t revealed molecular details of how the proteins work. Also, harvesting the proteins from fish is costly and timeconsum- ing, says chemist Robert N. Ben of the State University of New York at Binghamton.

I

destroy the natural glycoproteins, Ben says. That could make the new chemi- cals promising for ice-thwarting coat- ings, additives, or sprays for aircraft, concrete, or crops, he suggests.

Although the new molecules differ from the natural ones, Ben says prelimi- nary evidence suggests his compounds bind to ice and inhibit crvstal growth.

In the September-October BIOCONJU- GATE CHEMISTRY, Ben and his colleagues report a new method for chemically syn- thesizing molecules that resemble sug- arcontaining antifreeze proteins called antifreeze glycoproteins.

The new chemical strategy creates a whole family of compounds, each one a

AUGUST 25,2001

With an eye dn commercial possibili- Chi-Hing C. Cheng, a bolo& at the

Natural antifreeze keeps the Antarctic mackerel icefish supple.

good antifreeze activity, she says. If the new molecules do prove as

ties, the Binghamton team strengthened each of its molecules by creating a strong carbon-carbon bond in the loca- tion where the natural glycoproteins contain a weaker carbon-oxygen bond. With this added muscle, the synthetic molecules remain intact under certain chemical and biological conditions that

effective as natural agents, ihen the new synthesis techniques Ben’s team developed might suggest a route to com- mercially viable antifreeze products, comments biochemist Robert E. Feeney of the University of California, Davis. A specific application would be to prevent the buildup of gritty ice granules in ice cream, he says. -.l Gorman

SCIENCE NEWS, VOL. 160 119