Export 5 results:
Sort by: Author [ Title  (Asc)] Type Year
A B C D E F G H I J K L M N O [P] Q R S T U V W X Y Z   [Show ALL]
Muhle, J, Ganesan AL, Miller BR, Salameh PK, Harth CM, Greally BR, Rigby M, Porter LW, Steele LP, Trudinger CM, Krummel PB, O'Doherty S, Fraser PJ, Simmonds PG, Prinn RG, Weiss RF.  2010.  Perfluorocarbons in the global atmosphere: tetrafluoromethane, hexafluoroethane, and octafluoropropane. Atmospheric Chemistry and Physics. 10:5145-5164.   10.5194/acp-10-5145-2010   AbstractWebsite

We present atmospheric baseline growth rates from the 1970s to the present for the long-lived, strongly infrared-absorbing perfluorocarbons (PFCs) tetrafluoromethane (CF(4)), hexafluoroethane (C(2)F(6)), and octafluoropropane (C(3)F(8)) in both hemispheres, measured with improved accuracies (similar to 1-2%) and precisions (<0.3%, or <0.2 ppt (parts per trillion dry air mole fraction), for CF(4); <1.5%, or <0.06 ppt, for C(2)F(6); <4.5%, or <0.02 ppt, for C3F8) within the Advanced Global Atmospheric Gases Experiment (AGAGE). Pre-industrial background values of 34.7 +/- 0.2 ppt CF(4) and 0.1 +/- 0.02 ppt C(2)F(6) were measured in air extracted from Greenland ice and Antarctic firn. Anthropogenic sources are thought to be primary aluminum production (CF(4), C(2)F(6), C(3)F(8)), semiconductor production (C(2)F(6), CF(4), C(3)F(8)) and refrigeration use (C(3)F(8)). Global emissions calculated with the AGAGE 2-D 12-box model are significantly higher than most previous emission estimates. The sum of CF(4) and C(2)F(6) emissions estimated from aluminum production and non-metal production are lower than observed global top-down emissions, with gaps of similar to 6 Gg/yr CF(4) in recent years. The significant discrepancies between previous CF(4), C(2)F(6), and C(3)F(8) emission estimates and observed global top-down emissions estimated from AGAGE measurements emphasize the need for more accurate, transparent, and complete emission reporting, and for verification with atmospheric measurements to assess the emission sources of these long-lived and potent greenhouse gases, which alter the radiative budget of the atmosphere, essentially permanently, once emitted.

Vollmer, MK, Weiss RF, Williams RT, Falkner KK, Qiu X, Ralph EA, Romanovsky VV.  2002.  Physical and chemical properties of the waters of saline lakes and their importance for deep-water renewal: Lake Issyk-Kul, Kyrgyzstan. Geochimica Et Cosmochimica Acta. 66:4235-4246.   10.1016/s0016-7037(02)01052-9   AbstractWebsite

The relationships between electrical conductivity, temperature, salinity, and density are studied for brackish Lake Issyk-Kul. These studies are based on a newly determined major ion composition, which for the open lake shows a mean absolute salinity of 6.06 g kg(-1). The conductivity-temperature relationship of the lake water was determined experimentally showing that the lake water is about 1.25 times less conductive than seawater diluted to the same absolute salinity as that of the lake water. Based on these results, an algorithm is presented to calculate salinity from in-situ conductivity measurements. Applied to the field data, this shows small but important vertical salinity variations in the lake with a salinity maximum at 200 m and a freshening of the surface water with increasing proximity to the shores. The algorithm we adopt to calculate density agrees well with earlier measurements and shows that at 20degreesC and I atm Lake Issyk-Kul water is about 530 g m(-3) denser than seawater at the same salinity. The temperature of maximum density at I atm is about 0.15degreesC lower than that for seawater diluted to the same salinity. Despite its small variations, salinity plays an important role, together with temperature changes, in the static stability and in the production of deep-water in this lake. Changes in salinity may have had important consequences on the mixing regime and the fate of inflowing river water over geological time. Uncharged silicic acid is negligible for the stability of the water column except near an similar to15 m thick nepheloid layer observed at the bottom of the deep basin. Copyright (C) 2002 Elsevier Science Ltd.

Weiss, RF.  1968.  Piggyback sampler for dissolved gas studies on sealed water samples. Deep-Sea Research. 15:695-699.   10.1016/0011-7471(68)90082-x   AbstractWebsite

A sampler which obtains leak-proof sealed water samples from any depth has been developed for the study of dissolved gases. Closing of the sampler is activated by the tripping of the Nansen bottle to which it is attached. The water collected by the sampler is thus taken at the same time and place at which the Nansen bottle measures thermometric depth and temperature and collects water for measurement of salinity and other properties. Other advantages include ease of operation and low cost. The sampler has been tested at sea under a wide range of conditions.

Weiss, RF, Craig H.  1973.  Precise shipboard determination of dissolved nitrogen, oxygen, argon, and total inorganic carbon by gas chromatography. Deep-Sea Research. 20:291-303.   10.1016/0011-7471(73)90054-5   AbstractWebsite

A seagoing gas chromatographic system for the rapid and precise determination of dissolved gases in sea water is described. Separate instruments are employed for total inorganic carbon, and for nitrogen, oxygen, and argon analyses. Factors affecting the design, calibration, and shipboard operation of the system are discussed in detail. Results of intercomparisons with other analytical techniques confirm the accuracy of the gas chromatographic method. Profiles of ΣCO2, O2, and N2 measured aboard ship are presented and discussed.

Weiss, RF, Craig H.  1976.  Production of atmospheric nitrous oxide by combustion. Geophysical Research Letters. 3:751-753.   10.1029/GL003i012p00751   AbstractWebsite

Measurements of N2O in the effluent gases from the burning of coal and fuel oil show that these are significant anthropogenic sources of atmospheric N2O. We estimate that the present global production of N2O from these sources is 1.6 Mtons N2O(N) per year and is increasing at a rate of ∼ 3.5% per year. Catalytic converters for the reduction of NO emissions also represent a major potential source of atmospheric N2O.