Dataset: sediment
Deployment: NABE_N48

  PI:              Susumu Honjo and Steve Manganini
  of:              Woods Hole Oceanographic Institution
  dataset:         Sediment trap data, biogenic particle fluxes
  dates:           April 4, 1989 to April 17, 1990
  location:        N: 48  S: 34  W: -21  E: -21
  project/cruise:  North Atlantic Bloom Experiment cruises

NOTES:   specific for each trap

Trap #1 at 34N - 21W
PERIODS 1 THRU 13 TRAP DEPTH = 1071M
PERIODS 14 THRU 27 TRAP DEPTH = 1248M
PERIODS 3 THRU 14, RESTRICTED COLLECTION DUE TO PARTIAL CLOGGING OF THE
          SEDIMENT-TRAP APERTURE CAUSED BY A FISH-HEAD.
PERIOD 14 -  NO DATA, MOORING REDEPLOYMENT
PERIOD 27 -  NO DATA, TOTAL CLOGGING OF THE SEDIMENT-TRAP APERTURE DUE TO
          A FISH-HEAD OBSTRUCTION.

Trap #2 at 34N - 21W
PERIODS 1 THRU 13 TRAP DEPTH = 2067M
PERIODS 14 THRU 27 TRAP DEPTH = 1894M
PERIOD 14 -  NO DATA, MOORING REDEPLOYMENT

Trap #3 at 34N - 21W
PERIODS 1 THRU 13 TRAP DEPTH = 4564M
PERIODS 14 THRU 27 TRAP DEPTH = 4391M
PERIOD 14 -  NO DATA, MOORING REDEPLOYMENT
PERIODS 9 AND 11 SAMPLES DESTROYED IN TRANSIT

Trap #1 at 48N - 21W
PERIODS 1 THRU 13 TRAP DEPTH = 1018M
PERIODS 14 THRU 27 TRAP DEPTH = 1202M
PERIOD 14 -  NO DATA, MOORING REDEPLOYMENT

Trap #2 at 48N - 21W
PERIODS 1 THRU 13 TRAP DEPTH = 2018M
PERIODS 14 THRU 27 TRAP DEPTH = 2200M
PERIOD 14 -  NO DATA, MOORING REDEPLOYMENT
PERIODS 18 THRU 27 NO DATA, SEDIMENT TRAP APERTURE CLOGGED

Trap #3 at 48N - 21W
PERIODS 1 THRU 13 TRAP DEPTH = 3718M
PERIODS 14 THRU 27 TRAP DEPTH = 3749M
PERIOD 14 -  NO DATA, MOORING REDEPLOYMENT

Reference:  Honjo, S and Steven Manganini, 1992.  Biogenic Particle Fluxes
at the 34N 21W and 48N 21W Stations, 1989-1990:  Methods and Analytical
Data Compilation.  Woods Hole Oceanographic Institution Technical Report
WHOI-92-15.

Sediment Trap Particle Flux data during the North Atlantic Bloom Experiment
Dr. Susumu Honjo and Dr. Steven J. Manganini

Woods Hole Oceanographic Institution

The following methods documentation was extracted from:

Honjo, S, and S. J. Manganini, 1992.

Biogenic Particle Fluxes at the 34N 21W and 48N 21W Stations, 1989-1990:
Methods and Analytical Data Compilation. Woods Hole Oceanographic
Institution, Technical Report 92-15

Methods

A. Deployment of Sediment Traps and Mooring Arrays

1. Location, depths and timing:

   Two deep ocean mooring arrays were deployed at about 34N (depth
   to seafloor: 5,261 m and 5,083 m, for phase 1 and 2) and 48N (depth
   to seafloor: 4,418 m and 4,451 m). Table 1 gives more detailed information
   on mooring locations, trap depths and names of ships that were used
   for deployment and recovery. Three PARFLUX Mark 7G-13 time-series
   sediment traps with 13 rotary collectors on each were deployed on
   both moorings for a total of 6 traps. At each of the stations, traps
   were moored at approximately the same depth relative to the surface
   and the sea- floor (for the deepest trap); 1 km and 2 km from the
   surface and 0.7 km above bottom.

                                 TABLE 1
   
   Sediment Trap deployments, North Atlantic Bloom Exp., Dr. S. Honjo
   
   Mooring Stations and Trap Depths 
    
   Phase 1:  Periods 1 to 13, April 3, 1989 to Sept. 26, 1989 
   Phase 2:  Periods 14 to 27, Oct. 16, 1989 to April 16, 1990 
   Hiatus :  Sept. 26 1989 to Oct 16, 1989
    
    
                       34N 21W Station                48N 21W Station            
                   Phase 1         Phase 2         Phase 1         Phase 2 
   Latitude        33°49.3'N       33°48.4'N       47°42.9'N       47°43.6'N 
   Longitude       21°00.5'W       21°02.2'W       20°52.5'W       20°51.5'W 
   Bottom Depth ** 5,261 m         5,083 m         4,418 m         4,451 m 
                                    
   Trap Depth      1,070 m         1,248 m         1,018 m         1,202 m 
     "    "        2,067 m         1,894 m         2,018 m         2,200 m 
     "    "        4,564 m         4,391 m         3,718 m         3,749 m 
    
   Deployed by     R/V Atlantis II R/V Endeavor    R/V Atlantis II R/V Endeavor 
   Recovered by    R/V Endeavor    RRV Darwin      R/V Endeavor    RRV Darwin 
    
   **       Depths are all corrected values 
   
   

   Arrays were deployed in March and April 1989, recovered and redeployed
   in September 1989, and totally recovered in April 1990 (Table 1). During
   the 376-day deployment (including 20 days of hiatus in the middle),
   each sediment trap was opened and closed 26 times, providing continuous
   time-series sampling at 14-day intervals, except for two periods. Table
   2 lists open/close schedules for which all the traps were uniformly
   programmed during the experiment. An independent monitoring mechanism
   installed with each trap (Honjo and Doherty, 1988) confirmed that the
   entire program was executed correctly and on schedule.

   
                                 TABLE 2 
    
   
   Synchronized Open/Close Schedule for All Traps 
   at the 34N and 48N, 21W Stations
   
   Period    Mid Date        Open/Close Date     Days Open   Elapsed Days
           JD*     CD*        JD*     CD*             
                                                   
   1       96      04/06/89   93      04/03/89        5       5
   2      105      04/15/89   98      04/08/89       14      19
   3      119      04/29/89  112      04/22/89       14      33
   4      133      05/13/89  126      05/06/89       14      47
   5      148      05/29/89  140      05/20/89       17      64
   6      164      06/13/89  157      06/06/89       14      78
   7      178      06/27/89  171      06/20/89       14      92
   8      192      07/11/89  185      07/04/89       14     106
   9      206      07/25/89  199      07/18/89       14     120
   10     220      08/08/89  213      08/01/89       14     134
   11     234      08/22/89  226      08/15/89       14     148
   12     248      09/05/89  241      08/29/89       14     162
   13     262      09/19/89  255      09/12/89       14     176
   14     279      10/06/89  269      09/26/89       20     196 (hiatus)
   15     296      10/23/89  289      10/16/89       14     210
   16     310      11/06/89  303      10/30/89       14     224
   17     324      11/20/89  317      11/13/89       14     238
   18     338      12/04/89  331      11/27/89       14     252
   19     352      12/18/89  345      12/11/89       14     266
   20       1      01/01/90  359      21/25/89       14     280
   21      15      01/15/90    8      01/08/90       14     294
   22      29      01/29/90   22      01/22/90       14     308
   23      43      02/12/90   36      02/05/90       14     322
   24      57      02/26/90   50      02/19/90       14     336
   25      71      03/12/90   64      03/05/90       14     350
   26      85      03/26/90   78      03/19/90       14     364
   27      99      04/09/90   92      04/02/90       14     378
   
   *CD = Calendar Date;  JD = Julien Date
   
   

2. Time-series sediment traps:

   Each sediment trap had an aperture of 0.5 m2, covered by baffles
   with 25mm diameter cells with the aspect ratio of 2.5. The included
   cone angle was 42 degrees and the structural frame was built of welded
   titanium The opening and closing of all 6 traps was synchronized with
   an error of less than one minute. The sample containers, 13 for each
   trap, were filled with in situ deep sea water were collected by a
   30 liter Niskin bottle prior to the deployment. Analytical grade formalin
   (S. Wakeham; personal communication, 1988) was added to make a 3%
   solution buffered with 0.1% sodium borate. Each of the 13 sample containers
   was completely filled with this sea water solution with preservative
   before the deployment of a trap. Individual sample containers were
   mechanically sealed from the ambient water before and after each collecting
   period (Honjo and Doherty, 1988).

3. Mooring array:

   The mooring design was based on the PARFLUX Sediment Trap Mooring
   Dynamics Package that has been used by us since 1979 (Honjo et al.,
   1992). A detailed design, parts listing and tension calculation of
   the NABE mooring array is available in Manganini and Krishfield, 1992,
   Cruise Report. The arrays were designed to maintain an average of
   180 kg of vertical tension throughout the tautline, with a total buoyancy
   of 1,114 kg that was balanced with a 1,590 kg (in-water weight) cast-iron
   anchor. Sediment traps were attached to a mooring in-line with three
   1-m polyethylene-jacketed bridles. The automatic collection mechanism
   (Honjo and Doherty, 1988) of the 6 sediment traps worked flawlessly
   throughout the duration of the experiment and provided us with a total
   of 156 samples each of which represents an individual key to the time-space
   matrix for the NABE experiment.

B. Laboratory Analysis

1. Pre-analysis treatment of samples:

   We measured the pH in supernatant in sample containers immediately
   after recovery of traps (Manganini and Krishfield, 1992, Cruise Report).
   Sample containers were then refrigerated on board at approximately
   2 to 4 degree C. Particle samples in (original) 250 ml, polyethylene
   centrifuging sample containers were transported to Woods Hole under
   refrigeration at approximately 1 to 2 degree C. We identified no swimmers
   from all samples collected by our experiment. The impact of swimmers,
   if any, was relatively small; it appears that they were all included
   with the >1 mm fractions.

2. Supernatant analysis:

   In the shore laboratory, first the liquid in a sample container
   was decanted and then filtered through a 0.45 um pore size Nucleopore
   filter leaving approximately 1/3 of the original volume. About 50
   ml of filtered liquid was then analyzed for total N, NO2, NO3, NH4,
   P, PO4 and SiO2 using an automatic nutrient analyzer (e.g. Grasshoff
   et al. 1983). We regarded all excess quantities above the ambient
   concentration as being dissolved from the trapped particles while
   stored in situ before the recovery and added to the particle fluxes
   after being stochastically converted to solids. The remaining liquid
   in the sampling containers was used as rinse water in the processing
   of the particulate portion in each specific sample. When additional
   rinse water was required during the course of analysis, for example,
   for sample splitting we used filtered and buffered deep Sargasso Sea
   water containing 3% formalin.

3. Water sieving:

   Particle samples were water-sieved through a 1-mm Nitex mesh. This
   was necessary to maintain precision during splitting of the major
   portion of the sediment that was 1
   mm fraction were large aggregates and fragmented gelatinous zooplankton.
   A sample caught in the 1 mm mesh was then re-suspended in the original
   seawater, stirred gently and poured onto a grid-printed, 47-mm Nucleopore
   filter with 2-um pore size, while applying gentle vacuum suction.
   While a sample on a filter was wet, the filter with the >1 mm fraction
   was cut into 4 equal pieces along the printed grid by a Teflon-coated
   blade; each aliquot was then immediately put back into the filtered
   original water for storage. When a >1 mm sample was too small to split,
   it was dried and homogenized by pulverization.

   Sediment that passed through the 1 mm mesh was further water- sieved
   through a 62-um Nitex sieve. Each fraction was split into 1/4 aliquots
   and then into 1/40 aliquots by a rotating wet- sediment splitter with
   4 and 10 splitting heads (Honjo, 1980). The average error during the
   splitting of NABE samples into 4 or 10 aliquots was 3.7% for the mm fraction. Wet splitting of the trap-collected sample is justified
   for multi-disciplinary research including biocoenosis studies. Once
   particle samples are dried, each becomes inseparable and unidentifiable.
   Consequently, biocoenosis research such as picking up foraminifera
   tests or identifying diatom frustules becomes impossible.

4. Total dry mass measurement:

   Dry mass was determined by weighing two 1/4 aliquots of >1 mm (whose
   flux was usually insignificant) and three 1/10 aliquots of on pre-weighed 47 mm, 0.45 um Nucleopore filters. Before weighing,
   the samples were rinsed 3 times with distilled water, dried in an
   oven at 60 deg. C for 24 hours and cooled in a desiccator for 4 hours.
   Total flux was calculated from dry weight of the above aliquots divided
   by aperture area of the trap and the time it was opened.

5. Sedimentary component analyses:

   The dried sample was pulverized and homogenized, then the two size
   fractions were recombined proportionally and analyzed with respect
   to concentrations of:

    
   
          a)   Carbonate: as CaCO3
          b)   Biogenic Opal
          c)   Organic carbon, nitrogen and hydrogen in the decalcified
                  fraction
          d)   Phosphorus
   
   

   a) Carbonate content was determined by a method based on a vacuum-gasometric
   technique developed by Ostermann, et al. (1989). A preweighed sample
   is introduced into a sealed reaction vessel containing concentrated
   phosphoric acid. The pressure due to the evolution of CO2 gas is proportional
   to the carbonate content when calibrated with appropriate standards
   and was recorded by a transducer. The results were calculated and reported
   as carbonate percent in the total sample.

   b) Biogenic opal was estimated from particulate, reactive Si, selectively
   leaching decalcified samples in a sodium carbonate solution (Eggimann,
   et al., 1980) and converting the Si content to SiO2 fluxes. A preweighed
   sample of approximately 10 mg along with 10 ml of 1 M Na2CO3 was sealed
   in a Teflon container. The samples were placed in a shaker bath at
   90 deg. C for 3 hours and then filtered through a 47-mm-diameter,
   0.45 um pore size Nucleopore filter using an all-plastic filtering
   apparatus. The filtrate at room temperature was neutralized with 0.2
   N HCl using methyl orange as an indicator. After appropriate dilution,
   content of Si was determined spectrophotometrically (Strickland and
   Parsons, 1972). The Si content was then converted to SiO2 and reported
   as particulate opal flux.

   c) Organic carbon, nitrogen and hydrogen were analyzed using a Perkin-Elmer
   Elemental Analyzer Model 240C. Preweighed samples on precombusted
   glass fiber filters were decalcified using 1N phosphoric acid.

   d) Reactive (biogenic) phosphorus content was determined by the
   Solorzano and Sharp method that was based on the dissolution of phosphorus
   by an acid after ashing, using MgSO4 as an oxidant. A preweighed sample
   was placed into a glass centrifuge tube along with 2 ml of 0.017 M
   MgSO4 and was dried at 90 degree C. The centrifuge tube containing
   the sample was ashed at 500 deg. C for 2 hours. After cooling, 5 ml
   of 0.2 M HCl was added and, with the centrifuge tube capped, was heated
   at 80 deg. C for 30 min. At room temperature, 5 ml of distilled H2O
   with one ml of reagent (Strickland and Parsons, 1972) was added and
   the centrifuge tube was shaken in a vortex shaker, then centrifuged.
   The concentration of phosphorus was determined spectrophotometrically
   in the supernatant and the results were reported as particulate phosphorus
   flux.

   Using the reported method, the lithogenic particles were too small
   to detect and were usually within the analytical error.

C. Restoration of dissolved components to particulate flux

The dissolution of collected particles in a bottle may occur as soon as
particles arrive in the bottle while it is open, or later when it is sealed.
Assuming that all dissolved portions remained in the recovered bottle, we
restored the dissolved components of Si, P and N by analyzing the supernatants
in sample bottles. We assumed that the elevated concentration above the
sea water initially used to fill the bottles was caused by dissolved components.
During the deployment of a trap, the sample bottles were open to the water
column only for the duration of collecting periods. While a bottle was open,
the bottle water which was placed in the bottle before deployment is exchanged
with ambient water. In case the nutrient concentration of the initial bottle
water is not equal to that of the ambient water, a correction had to be
made; we assumed that one half of the initial water was diluted by the ambient
water while the bottle was open. In practice, the effect on calculating
particle flux by the difference of nutrients in the initial sea water was
within analytical error.

References:

Grassholf, K., Ehrhardt, M. and Kremling K.,(eds), 1983

Method of Sea-Water Analysis. Weinheim, Verlag Chemie.

Honjo, S. and Doherty, K. W., 1988.

Large Aperture Time-series Sediment Traps; Design Objectives, Construction
and Application. Deep-Sea Research, 35(1): 133-149.

Honjo, S., Manganini, S.J., and Krishfield, R., 1989.

Cruise Report: JOGFS Leg 1, International Study of the North Atlantic
Bloom, R/V Atlantis II Voyage 119.2, Funchal to Reykjavik, March/April
1989. WHOI Technical Report WHOI-89-22, Woods Hole Oceanographic Institution.

Honjo, S., Spencer, D.W. and Gardner, W.D., 1992.

Sediment Trap Intercomparison Study in the Panama Basin, Deep-Sea
Research, 39: 333-358.

Manganini, S.J. and Krishfield, R., (in preparation)

Cruise Report: JGOFS Trap Deployment Legs 2 and 3, International
Study of the North Atlantic Bloom, R/V Endeavor, Voyage 203 and HMS
Charles Darwin 45B, WHOI Technical Report, Woods Hole Oceanographic
Institution.

Ostermann,D.R., Karbott, D., and Curry, W.B., 1990.

Automated System to Measure the Carbonate Concentration of Sediments.
WHOI Technical Report, WHOI-90-03, Woods Hole Oceanographic Institution.

Strickland, J.D.H. and Parsons, T.R., 1972.

A Practical Handbook of Seaweater Analysis. Fisheries Research Board
of Canada, Bulletin 169, 2nd edition, Ottawa, Canada.