News of the Week The enzyme that degrades lignin, Srinivasan tells C&EN, is a bit unusual because it cleaves both arylalkyl and aryl-aryl ether linkages. Such ether linkages a b o u n d in lignin, which is a major constituent of trees and woody plants such as sugarcane. The enzyme, which Srinivasan calls "aryl etherase" for want of a better name, accomplishes the lignin degradation in only two hours— a new record for this process. By contrast, other methods that can be used to break down lignin, such as the use of plant pathogens, usually take anywhere from two days to two weeks, he notes. The LSU finding could have enormous implications, he says, because lignin is a substantial industrial and agricultural waste problem. Paper and pulp mills in the U.S. alone produce some 40 million to 50 million tons of it a year. The pulping process, which involves the removal of lignin from wood, requires large amounts of energy and chemicals and takes place under harsh reaction conditions. If a biological lignin-degradation step could be inserted into the process, Srinivasan muses, expenditures of energy and chemicals could be reduced, and the pulping process made milder. Srinivasan and his coworkers, graduate students Younchae Chong, Jeffrey Cary, and Kenneth Narva, are working on several fronts, using university funds. For instance, they are sequencing the gene; they would like to immobilize the enzyme for use as a biocatalyst; and they want to elucidate the enzyme's mechanism of action and make it digest lignin even faster. •
Soil erosion reducing food output capability Worldwide soil erosion is removing topsoil from the planet's croplands at a rate estimated to be 25.4 billion tons per year, according to a new report from Worldwatch Institute called "Soil Erosion: Quiet Crisis in the World Economy." This is faster than topsoil is generated, so that it is being depleted worldwide 0.7% each year, the report estimates. 6
October 1, 1984 C&EN
"In effect, the world is mining much of its cropland, treating it as a depletable resource, not unlike oil," the report says. The long-term effect is to reduce the soil's organic matter, damage its structural characteristics, and diminish its ability to retain nutrients. The immediate effects are subtle and, in the short term, can be masked by use of chemical fertilizers, the report says. Eventually, however, excessive soil loss leads to lower land productivity or higher food production costs. Studies in the U.S. corn belt indicate that each inch of topsoil lost reduces average yields 6%. Although estimates of soil loss in many developing countries are not very reliable, data from the "big four" food producers—the U.S., Soviet Union, India, and China—which together have 52% of the world's cropland, show they are losing some 13.2 billion tons of topsoil per year. In the U.S., which has some of the best data on soil erosion, 44% of cropland is losing topsoil faster than
it is being replaced by natural soil production. The changes in agricultural practices necessary to check soil erosion must be implemented by farmers, but governments must play a major role if the problem is to be corrected, the study says. First they need to make an inventory of soil losses so that national cost-benefit calculations can be made. Then, because erosion-producing practices usually are more profitable than conservation in the short term, governments will need to provide incentives for farmers to abandon shortterm profits for longer-term productivity. "During times of surplus, the U.S. government spends huge sums encouraging farmers to withold land from production," the study points out. "Unfortunately, no effort has been made to ensure that the most erosive land is set aside." Copies of the study are available for $4.00 from Worldwatch Institute, 1776 Massachusetts Ave., N.W., Washington, D.C. 20036. •
Terrorists bomb Carbide research center Terrorists opposing apartheid in South Africa exploded a bomb at Union Carbide's Tarrytown, N.Y., technical center last Wednesday night. The bomb, estimated by police to have contained 25 to 50 lb of dynamite, broke about 100 windows and blew a large hole in the outside of the research center's silicones building. No one was injured by the blast. Police in the nearby town of Greenburgh were warned of the bomb in a telephone call from a group identifying itself as the United Freedom Front and evacuated four maintenance workers from the site 10 minutes before the bomb went off at about 9:25 PM. The United Freedom Front is the same group that took responsibility for an explosion earlier in the week in a midtown Manhattan office building that houses the South African consulate. A Carbide spokesman says most of the damage, estimated to amount to about $500,000, was confined to the outside of the four-story building. The company doubts that inte-
rior damage to the structure, which is Carbide's primary site for silicones R&D, was extensive enough to have ruined any ongoing research projects. At press time, however, the Federal Bureau of Investigation had not yet given company officials access to the building. Carbide has operated mining, milling, and other facilities in South Africa since 1929, with sales last year totaling some $45 million, less than 0.5% of the corporation's total revenues. A company spokesman says Carbide opposes apartheid and is one of the original signers of the Sullivan Principles, a set of standards for business practice in South Africa promoted by antiapartheid groups in the U.S. The spokesman also points out that of Carbide's total South Africa workforce of 1850 employees, 1300 are nonwhite. Of that number, 38% are in white-collar positions, he says. In the aftermath of the explosion, the company says it is stepping up security at Tarrytown and other sites. •
