ATMOSPHERIC CHEMISTRY:
Levels of the greenhouse gas exceed industry’s estimates
T
HE FIRST ATMOSPHERIC measurements of nitrogen trifluoride, a potent greenhouse gas, indicate that the man-made gas, which is used in manufacturing electronics, is much more prevalent in the atmosphere than industry estimated, according to researchers at Scripps Institution of Oceanography (Geophys. Res. Lett. 2008, 35, L20821). Electronics manufacturers apply NF3 to clean chambers used for chemical vapor deposition of key compounds onto glass or silicon wafers. Laboratory studies indicate that the process destroys roughly 98% of NF3. NF3 is considered 17,000 times more potent as a global-warming agent than an equal mass of CO2. NF3’s warming potential was not evaluated until 2001, so it is not monitored under the Kyoto protocol. Earlier this year, atmospheric chemists Michael J. Prather and Juno Hsu of the University of California, Irvine, predicted that emissions of NF3 are likely greater than industry’s estimates. In addition, production of the gas has increased with growing demand for electronics products such as flat-panel displays. Prather and Hsu
DOW CONTESTS PESTICIDE BAN TRADE LAW: Company accuses
Quebec of prohibiting 2,4-D without scientific basis
D
OW AGROSCIENCES is challenging Quebec’s
provincewide ban on the residential use of weed-killing chemicals as a violation of the North American Free Trade Agreement (NAFTA) and is seeking at least $2 million in compensation from the Canadian government. The company, whose 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide is widely used to control broadleaf weeds, contends that the prohibition on lawn and garden chemicals is inconsistent with the investorprotection provisions of the trade agreement among Canada, the U.S., and Mexico. Quebec instituted its pesticide ban two years ago. Dow maintains that Canada has breached its obligations under Chapter 11 of NAFTA, which allows corporations to sue the federal government of any of the three countries for enacting laws or regulations that they believe harm their investments.
therefore called for atmospheric measurements of the gas (C&EN, July 14, page 6). Heeding the call, the Scripps researchers used gas chromatography and mass spectrometry to quantify NF3 in archived air samples collected from around the world over three decades. NF3 is notoriously difficult to separate from similarly volatile atmospheric gases, says Ray F. Weiss, a geochemistry professor who led the study. To get around the problem, his team prepared samples by using a chemical absorbent to remove carbon dioxide and low-temperature fractional distillation to separate other gases prior to analysis. Their results show that atmospheric NF3 has increased globally from about 0.02 ppt in 1978 to 0.454 ppt in July 2008. Atmospheric measurements provide an essential check on emissions estimates, which may have substantial errors because leakage rates during production and use are difficult to estimate, says Stephen A. Montzka, an atmospheric chemist at the National Oceanic & Atmospheric Administration, in Boulder, Colo. Mack McFarland, an atmospheric chemist at DuPont, says industry must now determine whether estimates of total NF3 use are correct and whether there are unaccounted emissions such as during production, transport, or use. Industrial groups welcomed the Scripps study. “Such measurement gives us a baseline for gauging our progress in further reducing NF3 emissions,” says Robert F. Brown, spokesman for Air Products & Chemicals, the world’s largest producer of the gas.—RACHEL PETKEWICH
SC R I PPS I NST. OF OC EA NOG RA PHY/UC SA N DI EG O
NF3 MEASURED IN AIR
Weiss (left), coauthor Jens Mühle, and colleagues measured NF3 levels in air samples.
Dow alleges that Quebec began a campaign against 2,4-D in 2002 without any O OH scientific basis for a ban. The company notes that a unit of the governmental O agency Health Canada concluded earlier Cl this year that 2,4-D can be used safely according to label directions for a variety of lawn, turf, and agricultural applications. Cl “The actions of the government of Quebec are tantamount to a blanket 2,4-Dichlorophenoxyacetic acid ban based on nonscientific criteria, and we are of the view that this is in breach to certain provisions of NAFTA,” says Jim Wispinski, president and CEO of Dow AgroSciences Canada. The company is seeking compensation of not less than $2 million, plus legal costs and unspecified damages. “This action by Dow is a blatant assault on the democratic process by a vested interest,” says Rick Smith, executive director of Environmental Defence Canada, a nonprofit group. “It’s also a boneheaded move from the company’s own [public relations] point of view. Parents are not going to look kindly on a corporation that tries to force pesticides down their children’s throats.” Pesticide bans are spreading in Canada. In June, Ontario passed legislation that will prohibit the sale and use of pesticides for cosmetic use on lawns and gardens throughout Canada’s most populous province when it takes effect next spring.—GLENN HESS
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