Air samples collected at Majuro, Marshall Islands. (7°N,171°E)


SIL ID #       Identification Number used at the Stable Isotope Lab, 
                University of Washington.
Date           Date that this sample was collected.
CH4-SIL        Methane concentration (ppm) determined manometrically at SIL with 
                precision of ± 2%, see Quay et al. (1).
CH4-CMDL       Methane concentration (ppm) determined by gas chromatography by NOAA/CMDL
                laboratory with precsion of ±0.2%, see Dlugokencky et al. (2).
Del 13C        Measured 13C/12C in per mil (0/00) units, where
                del 13C(0/00) ={[(13C/12C)sample/(13C/12C)standard - 1]*1000}
                and the standard is VPDB, see Quay et al. (1).
                Del 13C (0/00) corrected for standard drift, see Quay et al. (1).



SIL ID #         Date       CH4-SIL CH4-CMDL Del 13C
TTIM0001         26-OCT-90     1.69   1.673  -47.27
TTIM0002         26-OCT-90     1.67   1.673  -47.22
TTIM0004         21-NOV-90     1.73   1.694  -47.34
TTIM0003         21-NOV-90     1.74   1.694  -47.37
TTIM0006         8-JAN-91      1.74   1.714  -47.42
TTIM0005         8-JAN-91      1.70   1.714  -47.27
TTIM0007         6-MAY-91      1.75   1.718  -47.44
TTIM0008         6-MAY-91      1.72   1.718  -47.55
TTIM0009         2-JUN-91      1.87   1.711  -47.22
TTIM0010         2-JUN-91      1.63   1.711  -47.45
TTIM0011         1-SEP-91      1.72   1.680  -47.10
TTIM0012         26-NOV-91     1.76   1.715  -47.06
TTIM0013         26-NOV-91     1.75   1.715  -47.60
TTIM0015         21-APR-92     1.73   1.730  -47.17
TTIM0014         21-APR-92     1.47   1.730  -47.06
TTIM0017         2-JUL-92      1.73   1.717  -47.40
TTIM0016         23-JUL-92     1.76   1.707  -47.25
TTIM0018         2-DEC-92      1.70   1.686  -47.27
TTIM0020         14-FEB-93     1.76   1.723  -47.50
TTIM0019         14-FEB-93     1.78   1.723  -47.37
TTIM0021         13-MAR-93     1.71   1.736  -47.61
TTIM0022         10-APR-93     1.74   1.725  -47.22


(1) Quay, P.D., J. Stutsman, D. Wilbur, A. Snover, E. Dlugokenky and T. Brown, (submitted),
Isotopic Composition of Atmospheric Methane, Global Biogeochemical Cycles.

(2) DLUGOKENCKY, E.J., K.A. MASARIE, P.M. LANG, P.P. TANS, L.P. Steele, and E.G. Nisbet.
 A dramatic decrease in the growth rate of atmospheric methane in the northern hemisphere during 1992.
 Geophysical Research Letters 20(1):45-48 (1994).