Chemical & Engineering News Digital Edition ... - IMM@BUCT

NF 3 MEASURED
IN AIR
ATMOSPHERIC CHEMISTRY:
Levels of the greenhouse gas
exceed industry’s estimates
THE 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 NF 3 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 NF 3 .
NF 3 is considered 17,000 times more potent as a
global-warming agent than an equal mass of CO 2 . NF 3 ’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 NF 3 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
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
NF 3 in archived air samples collected from around the
world over three decades.
NF 3 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
NF 3 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 Du-
Pont, says industry must now determine whether estimates
of total NF 3 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 NF 3 emissions,” says Robert F.
Brown, spokesman for Air Products & Chemicals, the
world’s largest producer of the gas.—RACHEL PETKEWICH
SCRIPPS INST. OF OCEANOGRAPHY/UC SAN DIEGO
Weiss (left),
coauthor Jens
Mühle, and
colleagues
measured NF 3
levels in air
samples.
DOW CONTESTS
PESTICIDE BAN
TRADE LAW: Company accuses
Quebec of prohibiting 2,4-D
without scientific basis
DOW 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.
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.
“The actions of the government of
Cl
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
WWW.CEN-ONLINE.ORG 9 NOVEMBER 3, 2008