File P16N.doc Last Update 2000.05.31 1.1) CRUISE REPORT: WHP LINE P16N Expedition: CGC-91 (Climate and Global Change 1991) Ship: NOAA Research Vessel Discoverer Leg 1: Seattle, WA- Hilo, Hawaii 14 Feb- 28 Feb 1991 Leg 2: Hilo, Hawaii- Seattle, WA 7 March 1991- 8 April 1991 Chief Scientist: John L. Bullister NOAA-PMEL 7600 Sand Point Way, NE Seattle, WA 98115 Tel: (206)526-6741 FAX: (206)526-6744 Internet: bullister@noaapmel.gov 1.2) CRUISE SUMMARY: Fig. 1 shows the station locations. A listing of station locations is given in the P16N.sea file. Fig. 2 shows the sampling depths for the 10 liter bottles along the section. 1.3) LIST OF PRINCIPAL INVESTIGATORS: Measurement PI Institution CTD S. Hayes PMEL CFCs J. Bullister PMEL Helium-3 W. Jenkins WHOI J. Lupton UCSB Tritium W. Jenkins WHOI Oxygen J. Swift SIO-ODF TCO2 R. Feely PMEL Alkalinity R. Feely PMEL pH R. Byrne USF DIC P. Quay UW C-14 (AMS) R. Key Princeton Nutrients J. Swift SIO-ODF DON P. Wheeler OSU ADCP S. Hayes PMEL 1.3.1) PARTICIPANTS: LEG 2 John Bullister PMEL CFCs/Chief Scientist David Wisegarver PMEL CFCs Fred Menzia PMEL CFCS Jeff Benson PMEL Rosette operations Tiffany Vance PMEL CTD Kristy McTaggert PMEL CTD Dana Greely PMEL rosette operations, CO2 Paulette Murphy PMEL CO2 Susan Leftwich AOML CO2 Jiarong Zhang UW DIC Mike Behrenfeld OSU Productivity Pat Wheeler OSU Productivity/DON Mary-Lynn Dickson OSU Productivity/DON Leonard Lopez SIO-ODF Large Volume C-14 Art Hester SIO-ODF Oxygen, nutrients Bob Key Princeton Large Volume C-14, AMS C-14 Tonya Clayton USF pH Kim Kelly PMEL Underway dissolved gases Kelly Roupe PMEL Helium-tritium Dan Lee PMEL CFCs/data processing Larry Murray NOAA-PMC CTD/salinity Rex Long NOAA-PMC salinity Clyde Kakazu NOAA-PMC CTD Eric Noah NOAA-PMC CTD John Nakamura NOAA-PMC CTD 1.4) RESULTS AND HIGHLIGHTS: Leg 1 of the CGC91 expedition consisted of 14 stations occupied along the transit from Seattle to Hilo. These stations were re-occupations of stations previously sampled by PMEL investigators in 1985 for various parameters, and are not part of any WHP section. Only 1 of the stations on Leg 1 (Sta. 13 at 21 20 N, 152 50 W), made on the appproach to Hilo, is included in this report Leg 2 consisted of 52 stations (Sta. 15-66) on a line extending nominally along about 152 W from Hilo, Hawaii (20 N) to Kodiak Alaska (57 N). This section roughly follows the track from Honolulu to Kodiak made in 1984 during the Marathon II Expedition (Martin et al, 1987). We obtained full water column CTD profiles at all stations. The CFC data have been submitted to the WHP Office. A detailed discussion of the CTD measurements, data acquisition techniques, post-cruise calibrations and processing is also given in McTaggart and Mangum (1995). A 24 position 10 liter rosette with Neil Brown MARK III CTD (NBIS serial # 1111) was used at all stations. Due to limitations in ship time and endurance of the Discoverer, station spacing was nominally set at 40 nautical mile intervals, with closer spacing near boundaries and topographic features. To improve vertical resolution (within the available time), we planned to alternate between single cast (24 bottle) and 2 cast (48 bottle) stations along the line. Large volume Gerard Barrel casts (for C-14) were planned at a nominal spacing of 5 degrees along the line. No floats, drifters or moorings were deployed or recovered during the expedition. Continuous underway measurements of sea surface temperature and salinity were recorded along the cruise track. Approximately 44 XBTs were launched along the section. 1.5) MAJOR PROBLEMS ENCOUNTERED ON THE CRUISE As anticipated for this region of the North Pacific in late winter, we encountered a series of storms along the cruise track. Bad weather caused the cancellation of several stations between about 20-48 N (see attached station listing and map). Severe weather caused us to skip all scheduled stations between 48-52 N on the northward transit along the line. We bypassed this region, and continued onward to complete the northern end of the line at Kodiak Island (57 N). We hoped to occupy the missed stations by re-tracing the track southward, but again experienced severe weather in this region, and were only partially successful in filling this gap. The center of this area (50 N, 152 W) was later crossed by a diagonal (SE-NW) section as part of WHP Line P17N in June 1993. A number of water samples were lost due to problems with the 24 position General Oceanics Rosettes used to close the sample bottles. Although 2 new units were purchased for use on this cruise, and we were careful not to exceed lanyard tension specifications, we experienced a number of difficulties with the Rosettes. The problems included double-trips, failures to confirm firings, and failures in closing bottles. Typically, these problems resulted in losses of from one to several samples per cast, but at several stations only a few bottles were closed successfully. The mechanical components in the rosette required frequent disassembly and re-alignment, often resulting in delays in deploying the CTD/rosette package. After re-adjustment, performance of these units often deteriorated after only a few casts. Most of the double trips and mis-firings were identified on board ship, and the correct closing depth determined from bottle salinity results. Additional mis-fires have been identified using other data, including dissolved nutrients, oxygen, CFCs and pH. We believe that most of the mis-fires have been identified, and that the bottle numbers (btlnbr) and corresponding ctd pressures (ctdprs) in the P16N.sea data file have been assigned correctly. After these checks were made, a bottle quality flag value of 2 has been assigned to these samples. As a result of the mechanical problems, bad weather, and reduced ship speed, we were forced to reduce the number of 2 cast stations made along the section. We experienced mechanical problems with some of the Gerard Barrels, especially during the first few stations attempted. This resulted in the loss of a number of large volume radiocarbon samples. Data from the Gerard Barrel casts has been processed by Robert Key at Princeton, and submitted to the WHP office in a seperate file (.LVS format). Summary: Despite the problems in fully completing the section as planned, we feel that the quality of the data at the stations sampled is generally good. References: Martin, M., Talley, L.D., DeSzoeke, R.A. (1987). Physical, Chemical and CTD Data from the Marathon II Expedition. Data Report 131, Reference 87-15, College of Oceanography, Oregon State University, Coravallis, OR. McTaggart, K.E., Mangum, L.J., (1995). CTD Measurements Collected on a Climate and Global Change Cruise (WOCE Section P16N) along 152 W during February-April, 1991. NOAA Data Report ERL PMEL-53, Pacific Marine Environmenal Laboratory, Seattle, WA. 3.) HYDROGRAPHIC MEASUREMENT TECHNIQUES AND CALIBRATIONS 3.1) BOTTLE SALINITY MEASUREMENTS: Bottle salinity analyses were performed in a climate-controlled lab using two Guildline Autosal Model 8400A inductive salinometers and IAPSO Stamdard Seawater from Wormley Batch P110. The commonly accepted precision of the Autosal is 0.001 psu, with an accuracy of 0.003 psu. Salinity samples were collected from each sample bottle at all stations by ship's personnel. Two samples were drawn from the deepest bottle at each station to monitor the drift of the Autosal instrument. The first deep sample was run that day, the second was run the following day. The autosals were standardized at the beginning of each day using one vial of standard seawater, and again at the end of each case of sample bottles. The drift during each run was monitored and individual samples were corrected for the drift during each run by linear interpolation. Bottle salinities were compared with computed CTD salinites to identify leaking bottles, as well as to monitor the conductivity sensor performance and drift. 3.2.) DISSOLVED OXYGEN, NUTRIENTS (following discussion provided by Kristin Sanborn at SIO-ODF) 1. STS/ODF DATA COLLECTION, ANALYSES, AND PROCESSING Gerard casts were carried out with ~270 liter stainless steel Gerard barrels on which were mounted 2-liter Niskin bottles with reversing thermometers. The Gerard barrels were numbered 81 through 94 and the piggy-back Niskin were numbered 61 through 71. Salinity check samples were analyzed by PMEL from the Niskin bot- tles for comparison with the Gerard barrel salinities to verify the integrity of the Gerard sample. Gerard pressures and tem- peratures were calculated from Deep-Sea Reversing Thermometer (DSRT) readings. Each DSRT rack normally held 2 protected (tem- perature) thermometers and 1 unprotected (pressure) thermometer. Thermometers were read by two people, each attempting to read a precision equal to one tenth of the thermometer etching interval. Thus, a thermometer etched at 0.05 degree intervals would be read to the nearest 0.005 degrees. Each temperature value is therefore calculated from the average of four readings. 1.1. Oxygen Samples were collected for dissolved oxygen analyses soon after the sampler was brought on board and after CFC and Helium were drawn. Nominal 100 ml volume iodine flasks were rinsed care- fully with minimal agitation, then filled via a drawing tube, and allowed to overflow for at least 2 flask volumes. Reagents were added to fix the oxygen before stoppering. The flasks were shaken twice; immediately, and after 20 minutes, to assure thorough dispersion of the Mn(OH)2 precipitate. The samples were analyzed within 4-36 hours except for Station 13, Casts 21 and 22, which were analyzed ten (10) days after they were drawn. Dissolved oxygen samples were titrated in the volume- calibrated iodine flasks with a 1 ml microburet, using the whole-bottle Winkler titration following the technique of Car- penter (1965). Standardizations were performed with 0.01N potas- sium iodate solutions prepared from preweighed potassium iodate crystals. Standards were run at the beginning of each session of analyses, which typically included from 1 to 3 stations. Several standards were made up and compared to assure that the results were reproducible, and to preclude basing the entire cruise on one standard, with the possibility of a weighing error. A correction (-0.014 ml/l) was made for the amount of oxygen added with the reagents. Combined reagent/seawater blanks were deter- mined to account for oxidizing or reducing materials in the reagents, and for a nominal level of natural iodate (Brewer and Wong, 1974) or other oxidizers/reducers in the seawater. The assay of the finest quality KIO3 available to ODF is 100%, +/-0.05%, but the true limit in the quality of the bottle oxygen data lies in the practical limitations of the present sam- pling and analytical methodology, from the time the bottle is closed through the calculation of oxygen concentration from titration data. Overall precision within a group of samples has been determined from replicates on numerous occasions, and for the system as employed on this expedition, one may expect +/-0.1 to 0.2%. The overall accuracy of the data is estimated to be +/-0.5%. Oxygens were converted from milliliters per liter to micro- moles per kilogram using the equation: O2[um/kg]=O2[ml/l]/(.022392*(1.0+sigma theta/1000.0)) The potential density anomaly, sigma theta, is the potential density in kg/m3 referenced to pressure=0, from which 1000 has been subtracted. 1.2. Nutrients Nutrients (phosphate, silicate, nitrate and nitrite) ana- lyses, reported in micromoles/kilogram, were performed on a Tech- nicon AutoAnalyzer. The procedures used are described in Hager et al. (1972) and Atlas et al. (1971). Standardizations were performed with solutions prepared aboard ship from preweighed standards; these solutions were used as working standards before and after each cast (approximately 24 samples) to correct for instrumental drift during analyses. Sets of 4-6 different con- centrations of shipboard standards were analyzed periodically to determine the linearity of colorimeter response and the resulting correction factors. Phosphate was analyzed using hydrazine reduc- tion of phosphomolybdic acid as described by Bernhardt & Wilhelms (1967). Silicate was analyzed using stannous chloride reduction of silicomolybdic acid. Nitrite was analyzed using diazotization and coupling to form dye; nitrate was reduced by copperized cad- mium and then analyzed as nitrite. These three analyses use the methods of Armstrong et al. (1967). Sampling for nutrients followed that for the tracer gases, CFC's, He, Tritium, and dissolved oxygen. Samples were drawn into ~45 cc high density polyethylene, narrow mouth, screw-capped bottles which were rinsed twice before filling. The samples may have been refrigerated at 2 to 6 deg C for a maximum of 15 hours. Nutrients were converted from micromoles per liter to micro- moles per kilogram by dividing by sample density calculated at an assumed laboratory temperature of 25 deg C. 1.3. Data Comparisons The oxygen and nutrient data were compared not only with the adjacent station, but also with historical data from Marathon II and Trans-Pacific Section 47N. The agreement was within normal analytical error. 2. REFERENCES Armstrong, F. A. J., C. R. Stearns, and J. D. H. Strickland, 1967. The measurement of upwelling and subsequent biologi- cal processes by means of the Technicon Autoanalyzer and associated equipment, Deep-Sea Research 14, 381-389. Atlas, E. L., S. W. Hager, L. I. Gordon and P. K. Park, 1971. A Practical Manual for Use of the Technicon AutoAnalyzer in Seawater Nutrient Analyses; Revised. Technical Report 215, Reference 71-22. Oregon State University, Department of Oceanography. 49 pp. Bernhardt, H. and A. Wilhelms, 1967. The continuous determination of low level iron, soluble phosphate and total phosphate with the AutoAnalyzer, Technicon Symposia, Volume I, 385- 389. Brewer, P. G. and G. T. F. Wong, 1974. The determination and distribution of iodate in South Atlantic waters. Journal of Marine Research, 32,1:25-36. Bryden, H. L., 1973. New Polynomials for Thermal Expansion, Adia- batic Temperature Gradient, Deep-Sea Research 20, 401-408. Carpenter, J. H., 1965. The Chesapeake Bay Institute technique for the Winkler dissolved oxygen method, Limnology and Oceanography 10, 141-143. Hager, S. W., E. L. Atlas, L. D. Gordon, A. W. Mantyla, and P. K. Park, 1972. A comparison at sea of manual and autoanalyzer analyses of phosphate, nitrate, and silicate. Limnology and Oceanography 17 931-937. Lewis, E. L., 1980. The Practical Salinity Scale 1978 and Its Antecedents. IEEE Journal of Oceanographic Engineering, OE- 5, 3-8. UNESCO, 1981. Background papers and supporting data on the Prac- tical Salinity Scale, 1978. UNESCO Technical Papers in Marine Science, No. 37, 144 p. 3.3.) Radiocarbon Results Small volume (AMS) samples were collected by Robert Key and processed at the AMS facility at WHOI. Information on processing and calibration of these samples is not included in this report. Results from several Large-Volume C-14 stations are included in the P16N.LVS file. These results have been provided by the University of Miami Tritium Laboratory, in Data Release #92-15, H. Gote Ostlund, Head. The following text is excepted from this report: General Comments on this Data Release (#92-15) As part of the WOCE Hydrographic Programme, the NOAA R/V Discoverer CGC91 Cruise was undertaken during 7 March- 8 April 1991. The cruise track followed the 152 W meridian from 20-57 N., during which time six stations were sampled for radiocarbon using large volume casts. The University of Washington Quaternary Research Lab received samples from three of those stations and the University of Miami Tritium Lab received samples from the remaining stations. Hydrographic data for the large volume stations were received from Scripps Ocean Data Facility and Bob Key, Princeton University. Total CO2 is in progress of being measured by Richard Feely, PMEL General Comments on C12 Data Both C14 and C13 measurements were performed on CO2 gas prepared from the sample material. The standard for C14 measurements is ths NBS oxalic acid standard or radiocarbon dataing. R-value is the ratio between the measured specific activity of the sample CO2 to a dC13 value of -9 per mille and age-correcetd from today to AD1950, all according to international agreement. Delta C14 is the deviation, (in per mil) from unity, of the activity ratio, isotope-corrected to a sampe dC13 value of -25 per mil. If ages are reported, they are in 'C14 years' (before AD1950), based on a "best" C14 half-life of 5730 years. Multiply the ages by 0.9721 to obtain ages based on the 'official' half-life of 5570. The quoted errors are 1 sigma, the uncertainty of the half-life (+-40y) not included. For further information on standards, etc, cf. preface to each issue of Radiocarbon, and papers by Broecker and Olson 91961), Stuiver and Robinson (1974) and by Stuiver (1980). References : Broecker, W.S., and E.A. Olson. 1961, Lamont Radiocarbon measurements VIII, Radiocarbon, 3, 176-274. Ostlund, H.G. (1992). WOCE Radiocarbon, Data Release 92-15. Tritium Laboratory, University of Miami, RSMAS, Miami, FL. Stuiver, M., and S.W. Robinson, 1974, University of Washington GEOSECS North Atlantic carbon-14 results, Earth Planet. Sci. Lett., 23, 87-90. Stuiver, M., 1980, Workshop on C14 data reporting, Radiocarbon, 22(3), 964-966. 3.4) CFC-11 AND CFC-12 MEASUREMENTS ON WOCE SECTION P16N Specially designed 10 liter water sample bottles were used on the expedition to reduce CFC contamination. These bottles have the same outer dimensions as standard 10 liter Niskin bottles, but use a modified end-cap design to minimize the contact of the water sample with the end-cap O-rings after closing. The O-rings used in these water sample bottles were vacuum-baked prior to the first station. Stainless steel springs covered with a nylon powder coat were substituted in place of the standard internal elastic tubing used to close Niskin bottles. Water samples for CFC analysis were usually the first samples collected from the 10 liter bottles. Care was taken to co-ordinate the sampling of CFCs with other samples to minimize the time between the initial opening of each bottle and the completion of sample drawing. In most cases, dissolved oxygen, helium-tritium, total CO2 and pH samples were collected within several minutes of the initial opening of each bottle. To minimize contact with air, the CFC samples were drawn directly through the stopcocks of the 10 liter bottles into 100 ml precision glass syringes equipped with 2-way metal stopcocks. The syringes were immersed in a holding tank of clean surface seawater until analyses. To reduce the possibility of contamination from high levels of CFCs frequently present in the air inside research vessels, the CFC extraction/analysis system and syringe holding tank were housed in a modified 20' laboratory van on the deck of the ship. For air sampling, a ~100 meter length of 3/8" OD Dekaron tubing was run from the CFC lab van to the bow of the ship. Air was sucked through this line into the CFC van using an Air Cadet pump. The air was compressed in the pump, with the downstream pressure held at about 1.5 atm using a back-pressure regulator. A tee allowed a flow (~100 cc/min) of the compressed air to be directed to the gas sample valves, while the bulk flow of the air (>7 liter/minute) was vented through the back pressure regulator. Concentrations of CFC-11 and CFC-12 in air samples, seawater and gas standards on the cruise were measured by shipboard electron capture gas chromatography (EC-GC), using techniques similiar to those described by Bullister and Weiss (1988). For seawater analyses, a ~30-ml aliquot of seawater from the glass syringe was transferred into the glass sparging chamber. The dissolved CFCs in the seawater sample were extracted by passing a supply of CFC-free purge gas through the sparging chamber for a period of 4 minutes at ~70 cc/min. Water vapor was removed from the purge gas while passing through a short tube of magnesium perchlorate dessicant. The sample gases were concentrated on a cold-trap consisting of a 3-inch section of 1/8-inch stainless steel tubing packed with Porapak C and Porapak T (60-80 mesh) immersed in a bath of isopropanol held at -20 degrees C. After 4 minutes of purging the seawater sample, the sparging chamber was closed and the trap isolated. The trap was then heated to 100 degrees C. The sample gases held in the trap were then injected onto a precolumn (12 inches of 1/8-inch O.D. stainless steel tubing packed with 80-100 mesh Porasil C, held at 90 degrees C), for the initial separation of the CFCs and other rapidly eluting gases from more slowly eluting compounds. The CFCs then passed into the main analytical column (10 feet, 1/8-inch stainless steel tubing packed with Porasil C 80-100 mesh, held at 90 degrees C), and then into the EC detector. The CFC analytical system was calibrated frequently using standard gas of known CFC composition. Gas sample loops of known volume were thoroughly flushed with standard gas and injected into the system. The temperature and pressure was recorded so that the amount of gas injected could be calculated. The procedures used to transfer the standard gas to the trap, precolumn, main chromatographic column and EC detector were similar to those used for analyzing water samples. Two sizes of gas sample loops were present in the analytical system. Multiple injections of these loop volumes could be done to allow the system to be calibrated over a relatively wide range of CFC concentrations. Air samples and system blanks (injections of loops of CFC-free gas) were injected and analyzed in a similar manner. The typical analysis time for a seawater, air, standard or blank sample was about 12 minutes. Concentrations of CFC-11 and CFC-12 in air, seawater samples and gas standards are reported relative to the SIO93 calibration scale (Cunnold, et. al., 1994). CFC concentrations in air and standard gas are reported in units of mole fraction CFC in dry gas, and are typically in the parts-per-trillion (ppt) range. Dissolved CFC concentrations are given in units of picomoles of CFC per kg seawater (pmol/kg). CFC concentrations in air and seawater samples were determined by fitting their chromatographic peak areas to multi-point calibration curves, generated by injecting multiple sample loops of gas from a CFC working standard (PMEL cylinder CC9944) into the analytical instrument. The concentrations of CFC-11 and CFC-12 in this working standard were calibrated before and after the cruise versus a primary standard (36743) (Bullister, 1984). No measurable drift in the concentrations of CFC-11 and CFC-12 in the working standard could be detected during this interval. Full range calibration curves were run at intervals of 1-2 days during the cruise. Single injections of a fixed volume of standard gas at one atmosphere were run much more frequently (at intervals of 1 to 2 hours) to monitor short term changes in detector sensitivity. Sample loops filled with CFC-free gas, and syringe samples of CFC-free water (degassed in a specially designed glass chamber) were also run to check sampling and analytical blanks. Previous studies of time-dependent tracers in this region of the North Pacific indicate that water at density sigma0 > 27.4 should have near-zero CFC concentrations during the time of the expedition. CFC-12 concentrations measured in deep samples along the section were typically at or near the detection limit (< 0.005 pmol/kg) of the analytical system. Blank corrections have been applied to the dissolved CFC-12 concentrations at 3 of the stations reported in the P16N.sea file (see table below). Typical CFC-11 concentrations measured in deep samples along the section had a median value of about 0.007 pmol/kg. The following table summarizes the blank corrections applied to the CFC measurements made during the expedition. Station CFC-11 blank correction CFC-12 blank correction (pmol/kg) (pmol/kg) 15 0.015 0 16 0.006 0.005 17-20 0.006 0 21-22 0.010 0 23-25 0.006 0 26-27 0.000 0 28-31 0.007 0 32-38 0.000 0 39-42 0.004 0 43 0.007 -0.003 44-55 0.004 0 56-57 0.006 0 58 0.016 0 59-64 0.004 0 65 0.004 -0.002 We attribute the persistent non-zero CFC-11 blank signal to a combination of slow release of CFC-11 from the walls and O-rings of the 10 liter bottles into the seawater samples, contamination during the transfer and storage of the seawater samples in glass syringes prior to analysis and, most importantly, from contamination events due to the discharges from the ship. A number of water samples had unexpectedly high CFC-11 and/or CFC-12 concentrations relative to adjacent samples. These anomolous samples appeared to occur more or less randomly during the cruise, and were not clearly associated with other features in the water column (eg. elevated oxygen concentrations, salinity or temperature features, etc.). This suggests that the high values were due to individual, isolated CFC contamination events. A number of seawater samples were severely contaminated with CFC-11 during the first (non-WHP) leg of this expedition, especially at Stations 6-8. The sudden appearance of high and variable CFC-11 concentrations in deep samples at Sta. 8 may have been due to the inadvertent discharge of wastewater from the ship which occurred at the start of the hydrocast at this station. At several stations along Leg 2, CFC-11 concentrations significantly higher than the mean blank values were measured in some deep samples. We attribute this to sporadic CFC-11 contamination of the 10 liter bottles, possibly due to contact of the bottles with an oil slick from the ship at the start of the casts. Throughout the cruise, the exhaust stacks of R/V Discoverer emitted a large amount of soot and oil onto the working area of the ship's fantail. Although precautions were taken to shield the rosette and bottles from direct deposition of this material, an oily surface film was sometimes observed in the water as the rosette was lowered on station. Some of the sporadic CFC-11 contamination observed during Leg 2 could have resulted from deposition of trace amounts of material on the inside of the bottles as the rosette descended through the surface layer. Measured concentrations for these anomolously high samples are included in this report, but are give a quality flag of 4 (bad measurement). The CFC-11/CFC-12 ratio for each sample was checked for consistency, and compared to CFC-11/CFC-12 ratios from samples above and below it in the profile, and to samples from adjacent stations. A quality flag of 3 (questionable) was applied to some CFC-11 and/or CFC-12 measurements which had an anomolous CFC-11/CFC-12 ratios and/or concentrations relative to surrounding samples. If one of the two gases was clearly anomolous, that gas was given the questionable flag. In some cases both gases were flagged as questionable. A total ~208 analyses of CFC-11 were assigned a flag of 3 and ~120 analyses of CFC-12 were assigned a flag of 3. A total of ~215 analyses of CFC-11 were assigned a flag of 4 and 59 CFC-12 samples assigned a flag of 4. On this expedition, we estimate overall precisions (1 standard deviation) of about 1% or 0.005 pmol/kg (whichever is greater) for dissolved CFC-11 and 2% or 0.005 pmol/kg (whichever is greater) for dissolved CFC-12 measurements (see listing of replicate samples given at the end of this report). CFC samples from stations 1-13 and Sta 15 are not included in this report. A value of -9.0 is used for missing values in the listings. In addition to the file of mean CFC concentrations included in the P16N.sea file, tables of the following are included in this report: Table 1a. P16N Replicate dissolved CFC-11 analyses Table 1b. P16N Replicate dissolved CFC-12 analyses Table 2. P16N CFC air measurements Table 3. P16N CFC air measurments interpolated to station locations References: Bullister, J.L. Anthropogenic Chlorofluoromethanes as Tracers of Ocean Circulation and Mixing Processes: Measurement and Calibration Techniques and Studies in the Greenland and Norwegian Seas, Ph.D. dissertation, Univ. Calif. San Diego, 172 pp. Bullister, J.L. and R.F. Weiss, Determination of CCl3F and CCl2F2 in seawater and air. Deep-Sea Research, 35 (5), 839-853, 1988. Cunnold, D.M., P.J. Fraser, R.F. Weiss, R.G. Prinn, P.G. Simmonds, B.R. Miller,F.N. Alyea, and A.J.Crawford. Global trends and annual releases of CCl3F and CCl2F2 estimated from ALE/GAGE and other measurements from July 1978 to June 1991. J. Geophys. Res., 99, 1107-1126, 1994. Table 1a. P16N Replicate dissolved CFC-11 Analyses STATION SAMP F11 F11 NUMBER NO. pM/kg Stdev 8 1106 3.900 0.004 10 1518 3.152 0.034 13 2206 -0.001 0.003 17 2616 1.988 0.001 19 2917 2.390 0.027 21 3218 2.252 0.021 22 3412 2.368 0.004 23 3523 2.169 0.010 24 3621 2.151 0.009 30 4416 0.177 0.010 32 4724 2.555 0.011 34 5001 2.222 0.019 35 5120 1.406 0.014 37 5308 2.398 0.023 42 5919 3.091 0.081 43 6018 0.689 0.003 43 6019 1.444 0.013 44 6114 2.762 0.006 44 6115 2.777 0.024 45 6218 0.789 0.003 48 6604 0.480 0.008 49 6714 0.664 0.015 50 6816 0.210 0.005 50 6822 3.973 0.014 51 6913 0.657 0.004 51 6922 4.209 0.012 52 7010 0.528 0.002 54 7324 4.396 0.067 56 7613 0.144 0.008 57 7721 1.310 0.001 58 7820 1.666 0.057 59 7914 0.053 0.004 59 7924 5.273 0.048 60 8101 0.316 0.004 60 8107 1.136 0.013 65 8616 0.282 0.001 66 8719 1.064 0.001 Table 1b. P16N Replicate dissolved CFC-12 Analyses STATION SAMP F12 F12 NUMBER NO. pM/kg Stdev 8 1106 1.831 0.000 10 1518 1.642 0.046 11 1814 0.001 0.003 12 1902 0.095 0.002 13 2206 0.003 0.000 19 2917 1.192 0.009 21 3218 1.170 0.013 22 3401 0.003 0.005 22 3412 1.242 0.009 23 3523 1.150 0.017 24 3621 1.156 0.002 30 4416 0.088 0.003 32 4724 1.339 0.013 34 4907 0.000 0.000 34 5001 1.090 0.000 35 5120 0.686 0.002 37 5308 1.209 0.024 42 5919 1.546 0.015 43 6018 0.328 0.003 43 6019 0.678 0.009 44 6114 1.362 0.001 44 6115 1.376 0.007 45 6218 0.365 0.002 48 6604 0.217 0.005 49 6714 0.310 0.001 50 6816 0.098 0.006 50 6822 1.947 0.081 51 6913 0.300 0.003 51 6922 2.085 0.000 52 7010 0.246 0.004 54 7319 0.323 0.011 54 7324 2.165 0.006 56 7613 0.067 0.001 57 7721 0.610 0.003 58 7820 0.790 0.001 59 7914 0.029 0.002 59 7924 2.584 0.014 60 8101 0.151 0.000 60 8107 0.521 0.000 65 8616 0.143 0.004 66 8719 0.490 0.001 Table 2. P16N CFC Air Measurements: Leg 1 Time F11 F12 Date (hhmm) Latitude Longitude PPT PPT 17 Feb 91 1621 49 00.0 N 135 00.0 W 266.0 502.3 17 Feb 91 1631 49 00.0 N 135 00.0 W 266.0 499.1 17 Feb 91 1645 49 00.0 N 135 00.0 W 267.3 500.2 19 Feb 91 0535 46 55.8 N 135 26.9 W 265.1 501.6 19 Feb 91 0545 46 55.8 N 135 26.9 W 264.8 502.0 19 Feb 91 0601 46 55.8 N 135 26.9 W 264.6 500.5 19 Feb 91 0611 46 55.8 N 135 26.9 W 264.3 503.1 21 Feb 91 0516 44 34.0 N 135 02.0 W 263.4 499.2 21 Feb 91 0527 44 34.0 N 135 02.0 W 263.1 497.3 21 Feb 91 0538 44 34.0 N 135 02.0 W 263.0 499.6 21 Feb 91 0551 44 34.0 N 135 02.0 W 263.2 501.7 24 Feb 91 2138 32 22.7 N 138 36.6 W 262.4 501.0 24 Feb 91 2151 32 22.7 N 138 36.6 W 262.5 501.2 24 Feb 91 2204 32 22.7 N 138 36.6 W 262.6 498.1 24 Feb 91 2216 32 22.7 N 138 36.6 W 262.7 499.9 24 Feb 91 2229 32 22.7 N 138 36.6 W 263.0 500.1 25 Feb 91 0619 32 22.7 N 138 36.6 W 262.4 497.7 25 Feb 91 0703 32 22.7 N 138 36.6 W 261.1 496.6 25 Feb 91 0714 32 22.7 N 138 36.6 W 262.4 496.8 25 Feb 91 1712 29 31.2 N 142 20.8 W 262.2 503.3 25 Feb 91 1725 29 31.2 N 142 20.8 W 262.9 504.1 25 Feb 91 1738 29 31.2 N 142 20.8 W 263.3 503.7 25 Feb 91 1750 29 31.2 N 142 20.8 W 263.5 503.7 25 Feb 91 1802 29 31.2 N 142 20.8 W 263.8 503.7 26 Feb 91 0121 28 42.3 N 143 25.6 W 257.3 491.4 26 Feb 91 0133 28 42.3 N 143 25.6 W 259.6 491.6 26 Feb 91 0145 28 42.3 N 143 25.6 W 258.7 492.5 26 Feb 91 0157 28 42.3 N 143 25.6 W 262.2 491.3 26 Feb 91 0209 28 42.3 N 143 25.6 W 266.2 496.5 26 Feb 91 0820 27 51.0 N 144 30.0 W 263.3 503.3 26 Feb 91 0831 27 51.0 N 144 30.0 W 263.9 502.1 26 Feb 91 0843 27 51.0 N 144 30.0 W 263.3 502.1 26 Feb 91 0937 27 51.0 N 144 30.0 W 264.4 501.6 27 Feb 91 2254 27 51.0 N 144 30.0 W 262.1 500.6 27 Feb 91 2306 27 51.0 N 144 30.0 W 262.6 502.0 27 Feb 91 2319 27 51.0 N 144 30.0 W 261.6 500.6 27 Feb 91 2331 27 51.0 N 144 30.0 W 262.0 502.5 27 Feb 91 2343 27 51.0 N 144 30.0 W 262.2 501.9 11 Mar 91 0355 22 40.0 N 152 00.0 W -9.0 -9.0 11 Mar 91 0439 22 40.0 N 152 00.0 W 265.9 -9.0 11 Mar 91 0451 22 40.0 N 152 00.0 W 268.7 -9.0 11 Mar 91 0503 22 40.0 N 152 00.0 W 268.0 -9.0 11 Mar 91 0546 22 40.0 N 152 00.0 W 262.1 497.8 14 Mar 91 1210 27 42.7 N 151 59.7 W 265.2 502.5 14 Mar 91 1221 27 42.7 N 151 59.7 W 264.0 502.2 14 Mar 91 1233 27 42.7 N 151 59.7 W 264.8 500.9 14 Mar 91 1245 27 42.7 N 151 59.7 W 264.4 501.6 14 Mar 91 1259 27 42.7 N 151 59.7 W 264.8 501.2 15 Mar 91 0733 28 40.0 N 152 00.0 W 261.8 500.2 15 Mar 91 0746 28 40.0 N 152 00.0 W 263.0 499.2 15 Mar 91 0760 28 40.0 N 152 00.0 W 263.9 504.1 16 Mar 91 1700 28 40.0 N 152 00.0 W 262.4 503.0 16 Mar 91 1712 28 40.0 N 152 00.0 W 263.2 502.8 16 Mar 91 1724 28 40.0 N 152 00.0 W 263.7 503.2 16 Mar 91 1736 28 40.0 N 152 00.0 W 267.0 507.2 16 Mar 91 1748 28 40.0 N 152 00.0 W 265.7 502.4 17 Mar 91 1710 32 08.6 N 152 00.1 W 261.4 502.0 17 Mar 91 1721 32 08.6 N 152 00.1 W 264.4 501.6 17 Mar 91 1733 32 08.6 N 152 00.1 W 263.8 501.3 17 Mar 91 1745 32 08.6 N 152 00.1 W 263.2 500.2 17 Mar 91 1759 32 08.6 N 152 00.1 W 264.5 501.3 20 Mar 91 0633 32 08.6 N 152 00.1 W 265.2 502.7 20 Mar 91 0645 32 08.6 N 152 00.1 W -9.0 -9.0 20 Mar 91 0657 32 08.6 N 152 00.1 W 264.4 501.9 20 Mar 91 0709 32 08.6 N 152 00.1 W 263.6 503.0 22 Mar 91 1205 40 16.9 N 152 00.7 W 263.4 500.5 22 Mar 91 1217 40 16.9 N 152 00.7 W 266.5 501.6 22 Mar 91 1233 40 16.9 N 152 00.7 W 264.5 500.9 22 Mar 91 1245 40 16.9 N 152 00.7 W 265.0 499.3 22 Mar 91 1257 40 16.9 N 152 00.7 W 266.2 499.1 23 Mar 91 1020 40 16.9 N 152 00.7 W 266.4 506.2 23 Mar 91 2039 41 59.9 N 151 59.5 W 264.7 503.7 23 Mar 91 2051 41 59.9 N 151 59.5 W 267.9 504.2 23 Mar 91 2103 41 59.9 N 151 59.5 W 267.4 504.5 23 Mar 91 2115 41 59.9 N 151 59.5 W 265.6 505.2 23 Mar 91 2127 41 59.9 N 151 59.5 W 267.6 507.3 24 Mar 91 1104 42 48.9 N 151 57.2 W -9.0 504.0 24 Mar 91 1116 42 48.9 N 151 57.2 W 268.3 504.6 24 Mar 91 1805 43 20.0 N 152 00.0 W 268.4 503.4 24 Mar 91 1817 43 20.0 N 152 00.0 W 268.4 504.4 24 Mar 91 1828 43 20.0 N 152 00.0 W -9.0 501.2 24 Mar 91 1840 43 20.0 N 152 00.0 W 269.5 500.6 27 Mar 91 0343 49 09.0 N 152 00.0 W 267.1 504.3 27 Mar 91 0356 49 09.0 N 152 00.0 W 269.0 503.8 27 Mar 91 0408 49 09.0 N 152 00.0 W 268.5 505.8 29 Mar 91 0804 53 10.0 N 150 29.0 W 266.4 503.0 29 Mar 91 0816 53 10.0 N 150 29.0 W 263.2 503.1 29 Mar 91 0833 53 10.0 N 150 29.0 W 262.4 504.1 29 Mar 91 0845 53 10.0 N 150 29.0 W 261.5 503.9 30 Mar 91 1718 55 26.7 N 152 35.9 W 267.1 504.5 30 Mar 91 1729 55 26.7 N 152 35.9 W 267.8 504.4 30 Mar 91 1741 55 26.7 N 152 35.9 W 268.4 506.7 30 Mar 91 1753 55 26.7 N 152 35.9 W 268.1 503.6 30 Mar 91 1804 55 26.7 N 152 35.9 W 268.0 505.1 1 Apr 91 1219 55 26.7 N 152 35.9 W 259.3 499.8 1 Apr 91 1232 55 26.7 N 152 35.9 W 262.4 503.7 1 Apr 91 1244 55 26.7 N 152 35.9 W 264.8 499.2 1 Apr 91 1300 55 26.7 N 152 35.9 W 264.5 498.5 2 Apr 91 1134 55 26.7 N 152 35.9 W 267.2 503.4 2 Apr 91 1146 55 26.7 N 152 35.9 W 267.9 504.9 2 Apr 91 1158 55 26.7 N 152 35.9 W 269.7 500.7 2 Apr 91 1210 55 26.7 N 152 35.9 W 267.9 502.2 Table 3. P16N CFC Air values (interpolated to station locations) STATION F11 F12 NUMBER Latitude Longitude Date PPT PPT 1 48 50.0 N 127 39.4 W 16 Feb 91 265.4 501.3 2 50 00.2 N 134 59.8 W 17 Feb 91 265.4 501.3 3 48 59.7 N 134 59.5 W 17 Feb 91 265.4 501.3 4 47 59.6 N 134 59.4 W 18 Feb 91 265.4 501.3 5 46 59.3 N 134 59.8 W 19 Feb 91 264.6 500.6 6 46 00.0 N 134 59.9 W 20 Feb 91 263.9 500.6 7 45 00.2 N 135 00.2 W 20 Feb 91 263.9 500.6 8 43 59.4 N 134 59.4 W 21 Feb 91 263.9 500.6 9 42 00.3 N 134 59.7 W 22 Feb 91 263.9 500.6 10 39 59.8 N 134 59.9 W 23 Feb 91 263.9 500.6 11 36 59.4 N 134 59.4 W 23 Feb 91 262.4 498.9 12 35 00.1 N 135 00.1 W 24 Feb 91 262.4 498.9 13 21 20.1 N 152 50.5 W 28 Feb 91 262.8 501.8 14 20 55.4 N 153 47.9 W 1 Mar 91 262.8 501.8 15 19 53.3 N 154 55.3 W 8 Mar 91 265.3 501.0 16 20 04.0 N 154 40.5 W 8 Mar 91 265.0 500.9 17 20 23.8 N 154 14.2 W 8 Mar 91 265.3 501.0 18 20 42.5 N 153 46.0 W 9 Mar 91 265.3 501.0 19 21 36.8 N 152 26.2 W 10 Mar 91 265.3 501.0 20 21 54.9 N 151 60.0 W 10 Mar 91 265.3 501.0 21 22 40.6 N 151 59.5 W 11 Mar 91 264.6 502.0 22 24 00.2 N 151 58.0 W 12 Mar 91 265.3 501.0 23 24 39.9 N 152 00.2 W 12 Mar 91 265.3 501.0 24 25 20.2 N 151 59.7 W 13 Mar 91 265.3 501.0 25 26 00.2 N 151 60.0 W 13 Mar 91 264.2 502.3 26 26 39.9 N 152 00.0 W 14 Mar 91 264.2 502.3 27 27 20.0 N 151 59.9 W 14 Mar 91 264.2 502.3 28 27 60.0 N 151 59.7 W 15 Mar 91 264.2 502.3 29 28 39.8 N 151 59.9 W 15 Mar 91 264.2 502.3 30 29 20.7 N 151 58.3 W 16 Mar 91 263.8 502.8 31 29 60.0 N 152 00.5 W 16 Mar 91 263.8 502.8 32 30 39.9 N 151 59.5 W 17 Mar 91 263.8 502.3 33 31 20.1 N 152 00.1 W 17 Mar 91 263.8 501.8 34 32 10.5 N 152 00.6 W 18 Mar 91 263.8 501.8 35 32 40.0 N 152 00.1 W 18 Mar 91 263.8 501.8 36 33 20.0 N 152 00.0 W 18 Mar 91 263.8 501.8 37 34 00.1 N 152 00.1 W 19 Mar 91 263.8 501.8 39 35 36.5 N 152 00.4 W 20 Mar 91 263.8 501.8 40 36 17.7 N 152 02.7 W 20 Mar 91 265.4 501.3 41 37 09.9 N 151 57.6 W 21 Mar 91 265.4 501.3 42 37 59.9 N 152 00.0 W 21 Mar 91 265.4 501.3 43 38 40.2 N 151 59.9 W 22 Mar 91 265.4 501.3 44 39 21.0 N 151 59.2 W 22 Mar 91 265.4 501.3 45 40 00.9 N 151 59.6 W 22 Mar 91 265.4 501.3 46 40 40.5 N 152 01.3 W 23 Mar 91 265.4 501.3 47 41 21.0 N 152 00.3 W 23 Mar 91 266.7 503.0 48 41 59.6 N 151 59.1 W 24 Mar 91 266.9 504.8 49 42 40.8 N 151 58.5 W 24 Mar 91 267.5 503.9 50 43 20.0 N 151 59.6 W 24 Mar 91 267.5 503.9 51 44 25.1 N 151 59.8 W 25 Mar 91 267.5 503.9 52 45 00.1 N 151 59.0 W 25 Mar 91 267.5 503.9 53 45 41.1 N 151 59.6 W 26 Mar 91 267.7 504.1 54 46 20.2 N 151 59.3 W 26 Mar 91 268.5 503.6 55 47 00.0 N 152 00.0 W 27 Mar 91 268.5 503.4 56 47 39.9 N 152 00.4 W 27 Mar 91 268.5 503.6 57 48 19.5 N 152 00.3 W 27 Mar 91 266.4 503.4 58 53 29.7 N 152 00.1 W 30 Mar 91 265.7 503.0 59 54 39.6 N 151 59.8 W 30 Mar 91 266.4 502.8 60 55 27.1 N 152 33.5 W 31 Mar 91 266.4 502.8 61 55 51.9 N 152 55.7 W 31 Mar 91 266.4 502.8 62 56 01.6 N 153 02.7 W 31 Mar 91 266.4 502.8 63 56 14.5 N 153 10.8 W 1 Apr 91 266.4 502.8 64 56 17.7 N 153 14.0 W 1 Apr 91 266.4 502.8 65 55 04.2 N 152 17.9 W 1 Apr 91 266.4 502.8 66 52 29.4 N 152 01.2 W 2 Apr 91 265.7 503.0 DIC and pH: Documentation provided by: Marilyn F. Roberts Pacific Marine Environmental Laboratory National Oceanic and Atmospheric Administration 7600 Sand Point Way NE Seattle, WA 98115 (206) 526-6252 Phone (206) 526-6744 FAX e-mail: roberts@pmel.noaa.gov http://www.pmel.noaa.gov/co2/co2-home.ht Additional details on the analytical techniques and data processing are available from the individual PIs, and from the Carbon Dioxide Information Analysis Center (CDIAC): http://cdiac.esd.ornl.gov/about/intro.html Total dissolved inorganic carbon (TCO2) The TCO2 concentration of seawater samples was determined by using the coulometric titration system (UIC Inc., Model 5011) described by Johnson et al. (1985, 1987). The standards used were Na2CO3 in a matrix of 0.7M KCl, and were analyzed daily. The batch of CRMs (Dr. Andrew Dickson, SIO) that was shipped for our cruise was not stable and we were not able to use them as reference materials. Batch 1 CRMs had been used on a previous cruise by our group. We were therefore able to reference our cruise data to Batch 1 CRMs by means of a non-certified seawater standard that had been collected on both cruises which gave similar results. Batch 1 CRM shipboard measurements yielded a mean value of 2017.0 +/- 2.5 umol/kg (n=25), which compares with 2020.2 +/- 0.8 umol/kg (n=12) certified by SIO. Data reported for this cruise have been corrected to the Batch 1 CRM value by adding the difference between the certified value and the mean shipboard CRM value (certified value - shipboard analyses). Seawater samples for TCO2 analysis were drawn from the Niskin-type samplers into 500mL borosilicate glass bottles and poisoned with 100uL of HgCl2. The samples were sealed with ground-glass stoppers coated with Type M Apiezon grease, and stored in a cooled environment before analysis (usually within 12 hours after collection). The sample was introduced into a calibrated, thermostated (25C) pipette (~50mL), and then transferred to the extraction vessel and acidified with 4.5 ml of 10% phosphoric acid (previously stripped of CO2). The evolved CO2 gas passed through an Orbo-53 tube to remove volatile acids other than CO2 and then into the titration cell of the coulometer by the N2 carrier gas. In the coulometric analysis of TCO2, all carbonate species are converted to CO2 (g) by addition of excess hydrogen to the seawater sample. The evolved CO2 gas is carried into the titration cell of the coulometer, where it reacts quantitatively with a proprietary reagent based on ethanolamine to generate hydrogen ions. These are subsequently titrated with coulometrically generated OH-. CO2 is thus measured by integrating the total charge required to achieve this. The entire sequence takes between 8 to 11 minutes. All reagents in the extraction/analytical system were renewed daily. pH Sample cells (10-cm pathlength spectrophotometric cells, 30-cm3 volume) were filled directly from the NiskinTM-type bottle using a 20-cm length of silicone tubing. A flushing volume of approximately 300 mL was used. Care was taken to eliminate bubbles from the sampling system, and the sample cell was sealed with PTFE caps while ensuring that there was no head space. All spectrophotometric pH measurements were made using the indicator m-Cresol Purple. Spectrophotometric cells were warmed to 25CC within the water bath of a refrigerated thermocirculator. Subsequently cells were cleaned and placed in the thermostated sample compartment of the spectrophotometer. Absorbance measurements were made at three wavelengths: a non-absorbing wavelength (730 nm) and wavelengths corresponding to the absorbance maxima of the alkaline (I2-, 578 nm) and acidic (HI-, 434 nm) forms of the indicator. Subsequently, one of the cell caps was removed and 0.08 cm3 of concentrated indicator (2 umol/cm3) was injected into the cell. The cell was capped, rapidly mixed and returned to the thermostated cell. Absorbance measurements were again made at 730 nm, 578 nm and 434 nm. Sample pH was then calculated using the equations and procedures of Clayton and Byrne (1993). The "total" pH scale is used, and pHT is reported in mol/kg of seawater. Clayton T. and Byrne, R. H., 1993. Spectrophotometric seawater pH measurements: total hydrogen ion concentration scale calibration of m-cresol purple and at-sea results., Deep Sea Res., 40, 2115-2129. Johnson, K.M., A.E. King, and J. McN. Sieburth (1985): Coulometric DIC analyses for marine studies: An introduction. Mar. Chem., 16, 61-82. Johnson, K.M., P.J. Williams, L. Brandstrom, and J. McN. Sieburth (1987): Coulometric total carbon analysis for marine studies: Automation and calibration. Mar. Chem., 21, 117-133. 3.5.) Tritium-helium data were not available at the time of this report.