**30. Benthic processes**

Michiel Rutgers van der Loeff, Jana Friedrichs, Haike Hölzen, Ola Holby,
Karin Lochte (all AWI), Bettina Löscher (NIOZ)

**Sediment data**

1.  The sediment data were determined in undisturbed sediment cores
    obtained by multiple corer at the stations indicated.

Microbiological data are given in the file **Bentbact.xls**

*Variables*:

1\. station = station numbers following the ship's protocol

2\. bottom depth = depth of water column (m)

3\. sediment layer = sediment horizon sampled (cm)

4\. bact.numb. = bacterial numbers (10e8 cells/ml)

5\. phospholipids = concentration of phospholipids (nmol/ml)

6\. FDA = hydrolysis rate of fluorescein diacetate (micromol/l/hr)

Variables 3)-6) were provided by

Karin Lochte

Baltic Sea Research Institute

Seestrasse 15, D-18119 Rostock

Tel.: +49(0)381-5197-250, Fax: +49(0)381-5197-440

E-mail: karin.lochte@io-warnemuende.de

[Methods (Karin Lochte):]{.underline}

1\. See ships protocol

2\. See ships protocol

3\. Sediment layer: Sediment cores were segmented into 0.5 cm layers
from 0 to 2 cm sediment depth; from 2 to 6 cm they were segmented into 1
cm layers; from 6 to 10 cm they were segmented into 2 cm layers. The
sediment layer depth gives the mean depth of the sample.

4\. Bacterial numbers: Bacteria were counted microscopically in the
sediment samples which had been stored fixed in 2% formaldehyde solution
and kept refrigerated at 4 °C. The samples are diluted 1:10000 with
filtered seawater, homogenized briefly by ultrasonication, stained 5 min
with acridine orange (0.01%), washed with citrate buffer (pH 4) and
filtered onto black 0.2 micrometer poresize polycarbonate filters
(Nucleopore). The filters are mounted on microscopic slides in Cargille
immersion oil and viewed at 1000x magnification (Zeiss Axioscope20,
filter system BP450-490/FT510/LP520, oil immersion objective
Plan-Neoflar 100). At least 200 cells per sample were counted.

5\. Phospholipids: Phospholipids were extracted from the sediments and
analysed as described in: Boetius, A., Lochte, K. (1994) Regulation of
microbial enzymatic degradation of organic matter in deep-sea sediments.
Mar.Ecol.Prog.Ser. 104, 299-307.

6\. Hydrolysis rate of fluorescein diacetate: The rate of hydrolysis of
fluorescein diacetate was determined in the sediment samples as
described in: Meyer-Reil,L.-A., Köster, M. (1992) Microbial life in
pelagic sediments: the impact of environmental parameters on enzymatic
degradation of organic material. Mar.Ecol.Prog.Ser. 81, 65-72.

Pore water data are given in the file **Bentpore.xls**

*Variables*

A\) Station, station numbers following the ships protocol

B\) AWI, AWI core number

C\) Sediment layer, mean depth of sediment horizon sampled (cm)

D\) Concentration of nitrite in porewater (µM)

E\) Concentration of nitrate in porewater (µM)

F\) Concentration of ammonium in porewater (µM)

G\) Concentration of phosphate in porewater (µM)

H\) Concentration of reactive silicate in porewater (µM)

I\) Flux of oxygen into the sediment (mmol/m2 d)

Variables C)-I) provided by

Ola Holby

Max-Planck-Institut für marine Mikrobiologie,

Celsiusstr. 1, 28 359 Bremen, Germany,

Tel: +494212028843,

Fax: +494212028690,

E-mail: Ola@Postgate.mpi-mm.uni-bremen.de

Methods (Ola Holby)

C\) Sediment layer: Sediment cores were segmented into layers from
0-0.5, 0.5-1, 1-2. 2-3, 3-5, 5-7 and 7-10 cm. Below 10 cm the cores were
segmented into 5 cm layers. The sediment layer depth gives the mean
depth of the sample.

D)-H) The porewater concentrations of NO2, NO3, NH4, PO4 and Si, were
analysed directly on board with an auto analyser according to Grasshoff
et al. (Methods of Seawater Analysis, Verlag Chemie, Weinheim, 419 pp,
1983). No precaution was taken to avoid contact with air.

I\) The flux of oxygen into the sediment was calculated with Fick's
first law, using oxygen profiles obtained in the ships refrigerated lab
with home-built Clark style electrodes (Revsbech, N. P., In situ
measurements of oxygen profiles of sediments by use of oxygen
microelectrodes. in *Polarographic Oxygen Sensors: Aquatic and
Physiological Applications,* edited by E. Gnaiger, and H. Forstner, pp.
265- 273, Springer, 1983)

Further pore water data (alkalinity and pH) as well as data of porosity
and sediment composition (Th-234 excess activity, organic carbon and
biogenic silica content) and fluxes between sediment and overlying water
are available upon request.

**Metals concentration in sediments**

Bettina Löscher (NIOZ)

BENTMETA.XLS

2.  The particulate matter samples on 142 mm filters were subjected to a
    sequential chemical leaching treatment in the clean laboratory. They
    were immersed in 4.5 M Q-acetic acid for 4 h at room temperature, to
    dissolve adsorbed cations, carbonate phases and reactive
    oxyhydroxides (LANDING and BRULAND, 1980; 1987). This was followed
    by a digestion in 2 M Q-HCl/1 M Q-HNO3 for again 4 h at room
    temperature to dissolve the more resistant Fe (III) oxyhydroxides
    (LEWIS and LANDING, 1991). The residual refractory material was
    taken in clean digestion vessels and totally digested with 3 ml
    Q-HCl, 1 ml Q-HNO3 and 1 ml ultra clean HF. After digestion in a
    microwave oven they were diluted with 5 ml saturated H3BO3 to
    neutralise the strong acid HF (Merck). The last digestion step was
    tested for total destruction with the reference material calcareous
    loam (BCR No. 141) and light sandy soil (BCR No. 142) for the metals
    Cu and Ni. The obtained values agreed with the certified values
    within the 95% confidence interval. The blanks of Fe ranged between
    0.43 and 5.67 pM, and between 0.07 and 1.07 nM for the acetic acid
    leaching step and the total destruction step, respectively. The
    blanks for the second leaching step were smaller than 0.01 nM. The
    detection limits, based on three times the standard deviation of the
    blanks, ranged between 1.57 and 3.15 pM, 0.6 and 7.8 pM, and 20ÊpM
    and 0.88 nM for the acetic acid leaching step, the second leaching
    step and the total destruction, respectively.

    For the total particulate Al data, the seawater samples were
    collected independently by F. Dehairs in the upper 600 m using an
    all-Teflon coated CTD/Rosette frame with NOEX samplers. Typical
    depths were 10, 50, 100, 150, 200, 250, 300, 350, 425, 500 and
    600 m. The seawater was transferred to 30-l acrylic (perspex)
    filtration units for filtration on Nuclepore membranes ( 47 mm, 0.4
    µm porosity) using pressure of filtered air. In general between 5
    and 24 litres seawater were filtered per sample. After filtration,
    membranes were dried at 50¡C and stored frozen in Millipore petri
    dishes until later analysis. At every station one blank membrane was
    dried and stored as done for the sample membranes. In the home
    laboratory filter samples were mineralised using a lithium
    metaborate (LiBO2; Specpure, Johnson & Matthey) fusion technique
    described in detail in DEHAIRS et al. (1990, 1991). Prior to the
    fusion of the samples in platinum crucibles at 1100¡C, the
    polycarbonate matrix of the membrane filters was gently combusted at
    400¡C. After fusion the samples were redissolved in hot (80¡C) HNO3
    (Merck, Suprapure) under constant stirring. Final sample solution
    (10 ml) was 8 % in HNO3 and 5 % in LiBO2. Al was analysed by
    simultaneous inductively coupled plasma optical emission
    spectrometry (Jobin-Yvon 48). Standards were prepared in a similar
    HNO3/LiBO2 matrix as the samples.