Publications

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2002
Min, DH, Bullister JL, Weiss RF.  2002.  Anomalous chlorofluorocarbons in the Southern California Borderland Basins. Geophysical Research Letters. 29   10.1029/2002gl015408   AbstractWebsite

During the past two decades, unexpectedly high concentrations of chlorofluorocarbons (CFCs) have been observed in the bottom waters of the Southern California Borderland Basins (SCBB), with relatively constant spatial distribution patterns. In contrast to offshore waters in this region, CFC concentrations below the oxygen minimum layer (OML) in the deep SCBB increase with depth. The uniformity of the bottom-enhanced CFC signals and the near-zero levels of tritium suggest that this feature is likely maintained by release of CFCs from sediments and vertical mixing, and not by dumped CFC-bearing materials or an intrusion of recently ventilated waters. We hypothesize that CFC scavenging processes, either on particulate organic matter or hydrocarbon residues from the adjacent natural seeps, occur in these high-productivity near-surface coastal waters. The subsequent release of CFCs at the bottom boundary layer during the degradation of particulate material may cause the anomalous CFC distributions in the SCBB.

2000
Rhew, RC, Miller BR, Weiss RF.  2000.  Natural methyl bromide and methyl chloride emissions from coastal salt marshes. Nature. 403:292-295.   10.1038/35002043   AbstractWebsite

Atmospheric methyl bromide (CH3Br) and methyl chloride (CH3Cl), compounds that are involved in stratospheric ozone depletion, originate from both natural and anthropogenic sources. Current estimates of CH3Br and CH3Cl emissions from oceanic sources, terrestrial plants and fungi, biomass burning and anthropogenic inputs do not balance their losses owing to oxidation by hydroxyl radicals, oceanic degradation, and consumption in soils, suggesting that additional natural terrestrial sources may be important(1). Here we show that CH3Br and CH3Cl are released to the atmosphere from all vegetation zones of two coastal salt marshes. We see very large fluxes of CH3Br and CH3Cl per unit area: up to 42 and 570 mu mol m(-2) d(-1), respectively. The fluxes show large diurnal, seasonal and spatial variabilities, but there is a strong correlation between the fluxes of CH3Br and those of CH3Cl, with an average molar flux ratio of roughly 1:20. If our measurements are typical of salt marshes globally, they suggest that such ecosystems, even though they constitute less than 0.1% of the global surface area(2), may produce roughly 10% of the total fluxes of atmospheric CH3Br and CH3Cl.

1999
Lefevre, N, Watson AJ, Cooper DJ, Weiss RF, Takahashi T, Sutherland SC.  1999.  Assessing the seasonality of the oceanic sink for CO2 in the northern hemisphere. Global Biogeochemical Cycles. 13:273-286.   10.1029/1999gb900001   AbstractWebsite

Seasonal CO2 fluxes are estimated from quarterly maps of Delta pCO(2) (difference between the oceanic and atmospheric partial pressure of CO2) and associated error maps. Delta pCO(2) maps were interpolated from pCO(2) measurements in the North Atlantic and the North Pacific Oceans using an objective mapping technique. Negative values correspond to an uptake of CO2 by the ocean. The CO2 flux for the North Atlantic Ocean, between 10 degrees N and 80 degrees N, ranges from -0.69 GtC/yr, for the first quarter (January-March), to -0.19 GtC/yr for the third quarter (July-September) using the gas exchange coefficient of Tans et al. [1990], satellite wind speeds, and a correction for the skin effect. On annual average, the North Atlantic ocean (north of 10 degrees N) is a sink of CO2 ranging from -0.23 +/- 0.08 GtC/yr (gas exchange coefficient of Liss and Merlivat [1986] with Esbensen and Kushnir [1981] wind field) to -0.48 +/- 0.17 GtC/yr (gas exchange coefficient of Tans et al. with satellite wind field). The CO2 flux for the North Pacific, between 15 degrees N and 65 degrees N, ranges from -0.66 GtC/yr from April to June to zero from July to September. For the Atlantic, the errors are generally small, that is, less than 0.19 GtC/yr, but for the Pacific considerably larger uncertainties are generated due to the less extensive data coverage. The northern hemisphere ocean (north of 10 degrees N) is a net sink of CO2 to the atmosphere which is stronger in spring (April-June), due to the biological activity, with an estimate of -1.23 +/- 0.40 GtC/yr averaged over this period. The annual mean northern hemisphere ocean flux is -0.86 +/- 0.61 GtC/yr.

1996
Landrum, LL, Gammon RH, Feely RA, Murphy PP, Kelly KC, Cosca CE, Weiss RF.  1996.  North Pacific Ocean CO2 disequilibrium for spring through summer, 1985-1989. Journal of Geophysical Research-Oceans. 101:28539-28555.   10.1029/96jc02100   AbstractWebsite

Extensive measurements of CO2 fugacity in the North Pacific surface ocean and overlying atmosphere during the years 1985-1989 are synthesized and interpreted to yield a basin-wide estimate of Delta fCO(2). The observations, taken from February through early September, suggest that the subtropical and subarctic North Pacific is a small sink for atmospheric CO2 (0.07 to 0.2 Gton C (half year)(-1) for the region north of 15 degrees N). Objective analysis techniques are used to estimate uncertainty fields resulting from constructing basin-wide contours of oceanic fCO(2) on the basis of individual cruise transects. The uncertainties are significant and imply that future sampling programs need to recognize that estimating oceanic uptake of anthropogenic CO2 from ship-transect observations of oceanic fCO(2) alone will require very extensive sampling.